Description:TECHNICAL FIELD
[0001] The present disclosure relates to robotic systems, in particular, the present disclosure relates to a robotic surgical system with a precision-aligned strain-wave gear assembly.
BACKGROUND
[0002] Robotic surgical systems have revolutionised modern surgical procedures by enabling minimally invasive approaches with enhanced precision and control. The robotic surgical systems employ robotic arms that manipulate specialised surgical instruments through small incisions in the patient's body. The performance of a robotic arm depends upon the accuracy of the joint modules of the robotic arm. The joint modules govern the articulation and movement of the robotic arm. The joint modules integrate motors, gearing systems, and position feedback mechanisms that work in conjunction to provide suitable performance.
[0003] Existing joint modules for robotic arms use internal magnetic encoders for measuring the rotational position of input and output shafts present in the robotic arm. The existing joint modules further use bearings for maintaining alignment of the rotating components such as shafts, gears, and magnetic encoders. However, such magnetic encoders suffer from mechanical misalignment due to tolerance stack-up during assembly of the robotic arm, leading to errors in shaft positioning and rotational measurement. Furthermore, the arrangement of the bearings is not always sufficient to maintain proper motion stability and alignment of the magnetic encoders and rotating components and introduce inaccuracies in torque control and rotational feedback. Thus, there exists a technical problem of how to ensure precise alignment and stable integration of encoder rings and rotating shafts within a compact joint module of the robotic arm.
[0004] Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks.
SUMMARY
[0005] The present disclosure provides a robotic surgical system with a precision-aligned strain-wave gear assembly. The present disclosure provides a solution to the technical problem of how to ensure precise alignment and stable integration of encoder rings and rotating shafts within a compact joint module of a surgical robotic arm. An aim of the present disclosure is to provide a solution that overcomes at least partially the problems encountered in the prior art by providing a strain-wave geared joint module that provides precise alignment and positioning of a joint module of a robotic arm.
[0006] One or more objectives of the present disclosure is achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.
[0007] In one aspect, the present disclosure provides a robotic surgical system comprising:
a patient-side cart comprising a plurality of robotic arms;
a surgeon console configured to receive inputs from a surgeon to control the plurality of robotic arms;
a vision cart configured to process and display images from a surgical site;
wherein at least one robotic arm of the plurality of robotic arms comprises a strain-wave geared joint module, the strain-wave geared joint
module comprising:
a rotor shaft;
a strain wave gear connected to the rotor shaft;
an electric motor comprising a stator and a rotor;
an output shaft operatively connected to the strain wave gear;
a plurality of bearings; and
an input encoder and an output encoder,
wherein the plurality of bearings are strategically positioned to maintain precise alignment between components, reduce wide-angle errors that can lead to uneven magnetic fields and torque fluctuations, reduce stack-up errors during multi-part assembly, and ensure axial stability of the output shaft, thereby providing a compact, precise, and durable joint module for the robotic arm.
[0008] The strain-wave geared joint module is configured to ensure precise geometric alignment among internal components (for example, the rotor shaft, strain wave gear, electric motor, and the input encoder and the output encoder). Misalignment among the internal components may lead to wide-angle errors. The wide-angle errors distort magnetic field distribution and cause torque ripple or instability in electric motor performance. Further, the positioning of the plurality of bearings reduces wide-angle errors. The positioning of the plurality of bearings reduces stack-up errors arising from dimensional variations and tolerance mismatches in multi-part assemblies. The reduction in stack-up errors reduces the risk of interference but also ensures consistent mechanical coupling throughout the drive train. Furthermore, the positioning of the plurality of bearings preserves coaxiality and coplanarity between both the input encoder and the output encoder and the rotor-stator assembly of the electric motor, useful for ensuring accurate encoder readings and real-time motion feedback. By simultaneously providing axial rigidity, rotational stability, and sensor alignment, the plurality of bearings enables the creation of a compact, robust, and suitable joint module.
[0009] In an implementation, the strain-wave geared joint module further comprises a housing comprising a motor housing and an encoder casing. The input encoder and the output encoder are positioned within the encoder casing to maintain accurate measurement and control of the strain-wave geared joint module. By enclosing the input encoder and the output encoder within the corresponding encoder casing, electromagnetic and mechanical noise from the electric motor is minimized, which preserves signal fidelity. The fixed positioning of the input encoder and the output encoder within the corresponding encoder casing ensures precise angular displacement measurement by eliminating encoder tilt or misalignment due to mechanical vibration or thermal expansion during operation.
[0010] In another implementation, the strain wave gear includes a wave generator connected to the rotor shaft; a wave generator bearing; a flex spline in contact with the wave generator via the wave generator bearing; and a circular spline in contact with the flex spline. The output shaft is connected to the flex spline via a flange. The assembly of the strain wave gear enables high-ratio, zero-backlash gear reduction within a compact footprint. The flange connection between the flex spline and the output shaft provides a rigid mechanical coupling, thereby ensuring that rotational displacement from the electric motor is transmitted with high positional accuracy to the end effector of the robotic arm, even under variable torque loads.
[0011] In yet another implementation, the plurality of bearings comprises six bearings including a first bearing positioned to connect a harmonic gear assembly to the flange on the output shaft;and a second bearing and a third bearing to maintain coplanarity and concentricity between the rotor and the stator; a third bearing and a fourth bearing positioned to maintain coplanarity and concentricity between the input encoder and the output encoder; and a fifth bearing and a sixth bearing positioned to ensure axial stability of the output shaft. In such an implementation, the first bearing ensures smooth torque transfer with minimal backlash. The second bearing and the third bearing reduces magnetic imbalance and torque fluctuation during motor operation. The third bearing and the fourth bearing maintain precise alignment of the input shaft and input encoder for accurate rotational position sensing. The fifth bearing and sixth bearing prevents output shaft displacement during dynamic loading.
[0012] In yet another implementation, the first bearing is fixed in a bearing housing in a base part of the motor housing and is in tight fit with the rotor shaft; the second bearing is connected to the rotor shaft and is housed in a brake mount through a bearing seat; the third bearing is tightly fitted with an encoder shaft connected to the rotor shaft; the fourth bearing is fixed in a bearing seat of the encoder shaft; the fifth bearing connects the strain wave gear to the flange on the output shaft; and the sixth bearing is tightly fixed to the output shaft and is housed in an adapter that acts as a mechanical stopper. The first bearing fitted in the motor housing anchors the rotor shaft and dampens radial displacement. The second bearing, housed in a brake mount, secures the opposite end of the rotor shaft and stabilises the rotor during braking events. The third bearing and the fourth bearing within the encoder shaft preserve rigid encoder positioning to prevent phase shift during shaft rotation. The fifth bearing supports torque transfer between the strain wave gear and the output shaft flange, while the sixth bearing, housed in the adapter acting as a mechanical stop, limits excessive axial movement and ensures terminal shaft positioning during high-precision tasks.
[0013] In yet another implementation, the strain-wave geared joint module further comprises an encoder shaft connected to the rotor shaft. The input encoder is affixed to the encoder shaft; an electromagnetic brake connected to the rotor shaft; and a control drive connected to the encoder casing and including an integrated encoder reader for reading both the input encoder and the output encoder. The electromagnetic brake mounted on the rotor shaft introduces an active braking mechanism for controlled joint stoppage or emergency hold without requiring external actuators. The control drive unit affixed to the input encoder casing integrates a dual encoder reader, enabling real-time acquisition of data of the input encoder and the output encoder within the same electrical pathway. The real-time acquisition of data of the input encoder and the output encoder improves the dynamic response and closed-loop control accuracy of the robotic arm.
[0014] In another aspect, the present disclosure provides a method for operating the robotic surgical system, the method comprising:
receiving surgeon inputs at the surgeon console;
processing the surgeon inputs to generate control signals;
transmitting the control signals to a patient-side cart comprising a plurality of robotic arms;
displaying images from a surgical site on a vision cart;
operating at least one robotic arm of the plurality of robotic arms by: rotating a rotor shaft connected to a strain wave gear;
causing a flex spline of the strain wave gear to move relative to a circular spline during rotation;
transferring torque to an output shaft; and
utilizing a plurality of bearings to maintain precise alignment between components, wherein the plurality of bearings provide stability and precision by preventing component tilting, reducing wide-angle errors, eliminating stack-up errors during multi-part assembly, and strengthening structural integrity of the joint module, thereby providing higher precision control and increased durability for robotic surgical procedures.
[0015] The method for operating the robotic surgical system achieves all the advantages and technical effects of the robotic surgical system of the present disclosure.
[0016] In an implementation, maintaining precise alignment between a rotor magnet and a stator coil of an electric motor using a first set of bearings; maintaining precise alignment between input and output encoders using a second set of bearings; ensuring axial stability of the output shaft using a third set of bearings; and reading position data from the input and output encoders using an integrated encoder reader in a control drive. The use of the first set of bearings to maintain concentric and coplanar alignment between the rotor magnet and the stator coil of the electric motor ensures that the magnetic axis of the rotor remains uniformly aligned with the electromagnetic field of the stator. The alignment between the rotor magnet and the stator coil is useful for producing symmetrical torque profiles, reducing cogging, and enhancing motor efficiency and positional responsiveness. The second set of bearings secures precise axial and radial positioning between the input encoder and the output encoder, ensuring phase coherence and eliminating positional offsets during rotation. Thereby, ensuring that encoder readings accurately represent both the commanded and actual positions, improving the fidelity of motion control. The third set of bearings is positioned to resist axial thrust and maintain longitudinal stability of the output shaft under varying dynamic loads, preventing displacement that may lead to angular inaccuracies. The encoder reader embedded in the control drive acquires synchronous data from both the input encoder and the output encoder through a unified signal processing path, reducing signal latency, eliminating wiring complexity, and enabling precise closed-loop control of the joint module.
[0017] In another implementation, rotating a wave generator connected to the rotor shaft; transferring torque from the flex spline to the output shaft via a flange; and activating an electromagnetic brake connected to the rotor shaft to stop rotation of the rotor shaft. As the wave generator rotates, the wave generator cyclically engages the flex spline with the circular spline, resulting in a gear reduction output with negligible backlash and high positional accuracy. The torque is then transferred from the flex spline to the output shaft via the flange connection, which provides a direct mechanical interface with high torsional rigidity, maintaining fidelity of torque transmission even under rapid directional changes or variable resistance at the surgical end-effector. The electromagnetic brake, mounted concentrically on the rotor shaft, engages to halt rotor rotation on command. The electromagnetic brake provides immediate stopping power without backlash, supporting operational safety during unintentional motion or during tool exchanges, and enabling precise holding of the joint position during surgical procedures.
[0018] In yet another aspect of the present disclosure provides a robotic arm for the robotic surgical system, the robotic surgical system comprising the patient-side cart, the surgeon console, and the vision cart, the robotic arm comprising:
the strain-wave geared joint module comprising:
a housing;
a rotor shaft;
a strain wave gear connected to the rotor shaft;
an electric motor;
an output shaft operatively connected to the strain wave gear;
a plurality of bearings; and
an input encoder and an output encoder;
a control drive connected to the housing; and
a surgical instrument interface configured to connect a surgical instrument to the robotic arm, wherein the plurality of bearings are strategically positioned to form a reduced stack-up chain that decreases manufacturing tolerance requirements while ensuring concentricity and coplanarity among components, and wherein the control drive reads both input and output encoders to maintain a compact and efficient design that provides precise position control and improved durability compared to conventional joint modules.
[0019] The robotic arm for the robotic surgical system achieves all the advantages and technical effects of the robotic surgical system of the present disclosure.
[0020] In an implementation, the plurality of bearings comprises six bearings including a first bearing positioned to connect a harmonic gear assembly to the flange on the output shaft;and a second bearing and a third bearing to maintain coplanarity and concentricity between the rotor and the stator; a third bearing and a fourth bearing positioned to maintain coplanarity and concentricity between the input encoder and the output encoder; and a fifth bearing and a sixth bearing positioned to ensure axial stability of the output shaft. In such implementation, the first bearing ensures smooth torque transfer with minimal backlash. The second bearing and the third bearing reduces magnetic imbalance and torque fluctuation during motor operation. The third bearing and the fourth bearing maintain precise alignment of the input shaft and input encoder for accurate rotational position sensing. The fifth bearing and sixth bearing prevents output shaft displacement during dynamic loading.
[0021] In another implementation, the housing includes a motor housing and an encoder casing; the rotor shaft comprises a first end and a second end; the strain wave gear is connected to the first end of the rotor shaft; and the control drive includes an integrated encoder reader for reading both the input and output encoders. The implementation ensures compact integration, allows both encoders to be read by a single reader, and maintains clean signal alignment from both input and output sides.
[0022] In yet another implementation, the strain wave gear includes a wave generator connected to the rotor shaft; a wave generator bearing; a flex spline in contact with the wave generator via the wave generator bearing, the flex spline comprising a base flex spline part, a cup wall part, and a toothed wall part; and a circular spline in contact with the toothed wall part of the flex spline. The implementation provides high torque with zero backlash, while keeping the gear system lightweight and compact for precise motion control.
[0023] In yet another implementation, the electric motor includes a stator coil affixed to an inner wall of a motor housing and a rotor magnet affixed to the rotor shaft, and the input and output encoders are positioned within an encoder casing. The implementation ensures stable magnetic interaction and placing both encoders in the encoder casing helps maintain alignment and reduce signal noise.
[0024] In yet another implementation, an encoder shaft is connected to the rotor shaft, and an electromagnetic brake is connected to the rotor shaft. The encoder shaft has the input encoder affixed to the encoder shaft, and the output shaft has the output encoder affixed to a projected circular part of the output shaft. The implementation improves control and safety by holding the rotor in place when needed, while keeping encoder positions stable and reliable.
[0025] It is to be appreciated that all the aforementioned implementation forms can be combined.
[0026] It has to be noted that all devices, elements, circuitry, units and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof. It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
[0027] Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations construed in conjunction with the appended claims that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
[0029] Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
FIG. 1 is a diagram illustrating a robotic surgical system, in accordance with an embodiment of the present disclosure;
FIG. 2A is a diagram illustrating an isometric view of an exemplary robotic arm of the robotic surgical system, in accordance with an embodiment of the present disclosure;
FIG. 2B is a diagram illustrating a cross-sectional view of the exemplary robotic arm of the robotic surgical system, in accordance with an embodiment of the present disclosure;
FIG. 3 is a diagram illustrating a cross-sectional view of a strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure;
FIG. 4 is a diagram illustrating an arrangement of bearings of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure;
FIG. 5 is a diagram illustrating a cross-sectional view of a portion of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure;
FIG. 6 is a diagram illustrating a cross-sectional view of an encoder shaft of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure;
FIG. 7 is a diagram illustrating a cross-sectional view of another portion of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure;
FIG. 8 is a diagram illustrating a cross-sectional view of yet another portion of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure;
FIG. 9 is a diagram illustrating a cross-sectional view of a control drive of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure; and
FIG. 10 is a flowchart illustrating a method for operating the robotic surgical system, in accordance with an embodiment of the present disclosure.
[0030] In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION OF EMBODIMENTS
[0031] The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
[0032] FIG. 1 is a diagram illustrating a robotic surgical system, in accordance with an embodiment of the present disclosure. With reference to FIG. 1, there is shown a robotic surgical system 100 including a patient-side cart 110,, a vision cart 120,, and a surgeon console 130..
[0033] The patient-side cart 110 refers to a mobile platform and comprises a plurality of robotic arms. The patient-side cart 110 is configured to support the plurality of robotic arms positioned adjacent to a patient during surgical procedures. The patient-side cart 110 includes a base mounted on wheels. The patient-side cart 110 further includes a vertical column extending upward from the base. The plurality of robotic arms extend from the vertical column of the patient-side cart 110.. In some implementations, the multiple robotic arms include four robotic arms in which three robotic arms 112 are configured for surgical instrument manipulation and one robotic arm 113 is configured for endoscopic imaging. The robotic arms 112 include primary segments, secondary segments, and tertiary segments connected by rotational joints. The rotational joints contain servo motors enabling precise angular positioning. The robotic arms 112 include surgical instrument holders 114 at distal ends. The surgical instrument holders 114 comprise mechanical interfaces and electrical connectors. The mechanical interfaces include spring-loaded clamps for instrument attachment. In an implementation, the surgical instrument holders 114 includes an actuator configured to attach the surgical instrument 140 to the surgical instrument holder 114 through the help of a sterile adapter. The electrical connectors transmit power and signals to mounted instruments. The patient-side cart 110 further includes at least one surgical instrument 140 mounted to the surgical instrument holders 114 at one of the robotic arms 112.. The surgical instrument includes elongated shafts with end effectors at distal tips. The end effectors include articulation mechanisms enabling pitch and yaw movements. The surgical instrument 140 includes internal drive cables connecting to motor units in the instrument holders. The drive cables actuate the end effector movements. The robotic arm 113 supports an endoscopic imaging system. Each of the robotic arms 112 includes additional degrees of freedom for camera positioning. The endoscopic imaging system includes dual high-definition camera sensors mounted at a distal end of the robotic arm 113.. The dual camera sensors enable stereoscopic image capture. The endoscopic imaging system includes fibre optic light transmission bundles surrounding the camera sensors for illuminating the surgical field. The endoscopic imaging system enables both white light imaging and near-infrared fluorescence visualization. The endoscopic imaging system comprises glass rod lenses for controlling chromatic aberration and enhancing image quality.
[0034] The vision cart 120 is a mobile unit comprising a base with wheels and a vertical housing. The base contains power supply units and cooling systems. The vertical housing contains processing units and displays. The vertical housing includes ventilation channels for thermal management. The vision cart 120 includes a display 122 mounted at an upper portion of the vertical housing, wherein the display 122 comprises a high-definition LCD monitor with anti-glare coating. In some other embodiments, the vision cart 120 may include multiple displays. The vision cart 120 includes an electrosurgical unit (ESU) 124 mounted within the vertical housing. The vision cart 120 further includes endoscope light sources. The endoscope light sources comprise one or two light source units mounted within the vertical housing. The vision cart 120 includes an insufflator unit mounted within the vertical housing for creating and maintaining pneumoperitoneum. The vision cart 120 includes an uninterruptible power supply (UPS) system mounted within the base for providing backup power. The vision cart 120 further includes a video processing unit and a central processing unit within the vertical housing. The video processing unit includes dedicated graphics processors. The central processing unit comprises multiple processing cores. The vision cart 120 further includes data storage devices mounted within the vertical housing. In some implementations, the vision cart 120 comprises image enhancement processors for contrast adjustment and noise reduction. In some implementations, the vision cart 120 includes fluorescence imaging processors for tissue identification. In some implementations, the vision cart 120 includes augmented reality processors for data overlay generation.
[0035] The surgeon console 130 includes a base structure supporting an operator seat and control interfaces. The base structure includes levelling mechanisms for stable positioning. The operator seat comprises height adjustment mechanisms and lumbar support systems. A display housing extends upward and forward from the base structure. The display housing contains a stereoscopic display system 134 for displaying real-time surgical site images in high resolution, providing enhanced depth perception and clarity. The stereoscopic display system 134 includes dual display panels and optical elements. The optical elements include focusing mechanisms and eye tracking sensors. In an implementation, the stereoscopic display system 134 is secured by a monitor mounting assembly, which enables adjustable positioning for optimal viewing angles. The monitor mounting assembly 136 may be referred to as an adjustable support system that securely holds and enables the controlled positioning of the stereoscopic display system 134 within a workstation or operational environment. The surgeon console 130 further includes master control manipulators 132 mounted on sides of the base structure in front of the operator seat. The master control manipulators 132 terminate in ergonomic hand grips. The hand grips contain pressure sensors and multi-function triggers. In some other embodiments, the hand grip provides haptic feedback.
[0036] In some implementations, the surgeon console 130 further includes foot pedals mounted on a lower portion of the base structure. The foot pedals include position sensors and tactile feedback mechanisms. A user interface comprising touchscreens mounts on the base structure between the master control manipulators 132.. The touchscreens display system status information and configuration controls.
[0037] The patient-side cart 110,, the vision cart 120,, and the surgeon console 130 connect through a communication network. In an implementation, the communication network may be through wired or wireless communication protocol. In an implementation, the communication between the patient-side cart 110,, the vision cart 120,, and the surgeon console 130 is established through etherCAT or ethernet. In some other embodiments, the communication may be through any wireless communication protocol.
[0038] The communication network includes redundant data pathways. The communication network transmits control signals from the master control manipulators 132 to the robotic arms 112.. The control signals include position commands and gripper actuation commands. In some implementations, the communication network transmits imaging data from the endoscopic imaging system to the stereoscopic display system 134.. The imaging data includes calibration parameters and camera position data. The robotic surgical system 100 includes monitoring systems connected to the communication network. The monitoring systems comprise voltage sensors, current sensors, temperature sensors, and position sensors.
[0039] In some implementations, the robotic surgical system 100 includes emergency stop mechanisms mounted on each component. The emergency stops mechanisms include physical switches and software-triggered stops. The robotic surgical system 100 includes power backup systems within each component. The power backup systems include batteries and uninterruptible power supplies. The robotic surgical system 100 includes fault detection processors within the vision cart 120.. The fault detection processors monitor system parameters and component status.
[0040] In some implementations, the robotic surgical system 100 executes autonomous and semi-autonomous functions. In some implementations, the robotic surgical system 100 enables system upgrades through modular component replacement. The modular component replacement includes instrument interface upgrades and processing unit upgrades. The robotic surgical system 100 enables minimally invasive surgical procedures. Exemplary surgical procedures may include, but not limited to, general surgery procedures, gynaecological procedures, urological procedures, cardiothoracic procedures, and otolaryngological procedures.
[0041] FIG. 2A is a diagram illustrating an isometric view of an exemplary robotic arm of the robotic surgical system, in accordance with an embodiment of the present disclosure. FIG. 2A is described in conjunction with the elements of FIG. 1. FIG. 2B is a diagram illustrating a cross-sectional view of the exemplary robotic arm of the robotic surgical system, in accordance with an embodiment of the present disclosure. FIG. 2B is described in conjunction with the elements of FIGs. 1 and 2A. With reference to FIGs. 2A and 2B, there is shown the robotic arm 112 for use with the robotic surgical system 100 described in FIG. 1. The robotic arm 112 includes a plurality of joints (for example, a first joint 202A, a second joint 206A, and a third joint 208A) that are configured to enable articulated movement of the robotic arm 112 in multiple directions. In the illustrated embodiment of FIGs. 2A and 2B, the robotic arm 112 is capable of movement along six independent axes. In other words, the robotic arm 112 possesses six degrees of freedom, allowing precise and flexible positioning required for surgical operations. The robotic arm 112 further includes a plurality of joint motor modules (for example, a strain-wave geared joint module 202B) housed within the first joint 202A for controlled movement of the robotic arm 112..
[0042] The strain-wave geared joint module 202B refers to a compact, integrated actuation unit configured to provide precise rotational movement at each joint of the plurality of joints of the robotic arm 112.. The strain-wave geared joint module 202B is structurally integrated within the joint housings of the robotic arm 112.. The strain-wave geared joint module 202B allows precise movement by converting input of an electric motor into rotational output. The transition of the electric motor input into rotational output helps reduce backlash, so the movement of the robotic arm 112 starts and stops exactly when commanded, without delay or overshoot. As a result, the robotic arm 112 can perform fine and controlled movements during surgical procedures.
[0043] In an implementation, the robotic arm 112 may have more than six degrees of freedom to enable enhanced reachability and orientation control during surgical procedures. In another implementation, additional degrees of freedom may be introduced through the integration of auxiliary joints along the robotic arm 112,, allowing for finer adjustments and greater flexibility within confined surgical workspaces. In yet another implementation, the robotic arm 112 may include one or more passive or redundant joints beyond the primary six, which assist in avoiding obstacles, minimizing joint singularities, or optimizing instrument positioning based on surgeon input or automated path planning.
[0044] The robotic arm 112 includes a first end 204A where a surgical instrument interface configured to connect the surgical instrument 140 to the robotic arm 112 is formed. The surgical instrument interface allows for the secure attachment and precise control of various surgical instruments, such as graspers, scissors, needle drivers, or cautery tools. The surgical instrument interface at 204A includes mechanical coupling mechanisms and electrical connections that transmit motion and control signals from the robotic arm 112 to the attached surgical instrument 140..
[0045] FIG. 3 is a diagram illustrating a cross-sectional view of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure. FIG. 3 is described in conjunction with the elements of FIGs. 1 to 2. With reference to FIG. 3, there is shown a cross-sectional view of the strain-wave geared joint module 202B of the robotic arm 112.. The strain-wave geared joint module 202B includes a rotor shaft 302 of the electric motor extending through a rotational axis of the strain-wave geared joint module 202B. The strain-wave geared joint module 202B further includes a rotor magnet 304 mechanically coupled to the rotor shaft 302,, and a stator coil 306.. The strain-wave geared joint module 202B further includes a motor housing 308 (hereinafter referred to as “the first housing 308”), a second housing 310 mechanically coupled with the first housing 308,, and an electromagnetic brake 312 connected to the rotor shaft 302.. The strain-wave geared joint module 202B further includes an encoder shaft 314 mechanically coupled to the rotor shaft 302,, an encoder casing 316 (hereinafter referred to as “the sub-housing 316”) mechanically coupled with the second housing 310.. Furthermore, the strain-wave geared joint module 202B includes a control drive 318,, an output shaft 320,, and an adapter 322.. The strain-wave geared joint module 202B further includes an output encoder 324,, an input encoder 326,, and a strain wave gear 328 operatively coupled to the rotor shaft 302..
[0046] The strain-wave geared joint module 202B is configured to provide precise rotational movement in the robotic arm 112.. The strain-wave geared joint module 202B reduces backlash and enables high reduction ratios, ensuring accurate positioning of the robotic arm 112 required for surgical procedures.
[0047] The rotor shaft 302 refers to a central, elongated rotating member that transmits torque generated by the electric motor to the strain wave gear 328.. The rotor shaft 302 forms the primary rotational axis of the strain-wave geared joint module 202B and serves as the mechanical interface between the rotor and the gear mechanism of the electric motor. The rotor shaft 302 is configured to rotate about the rotational axis and transmit rotational motion to the strain wave gear 328.. The rotor shaft 302 supports the rotor magnet 304.. The rotor magnet 304 is fixedly attached to the rotor shaft 302 by a tight fit.
[0048] The rotor magnet 304 refers to a cylindrical magnetic element integrated with the rotor shaft 302,, which rotates within the stator coil 306 to generate torque through electromagnetic interaction between the permanent magnetic field of the rotor magnet 304 and the rotating magnetic field generated by the stator coil 306.. The stator coil 306 refers to a stationary electromagnetic winding housed around the rotor magnet 304,, which produces a rotating magnetic field when energized with electric current. The stator coil 306 interacts with the rotor magnet 304 to induce motion in the rotor shaft 302.. The rotor magnet 304 is positioned in alignment with the stator coil 306.. The rotor magnet 304 and the stator coil 306 together form the electric motor. The stator coil 306 is arranged inside the first housing 308 and attached to an inner wall of the first housing 308.. The first housing refers to the structural casing or enclosure that supports, aligns, and protects internal components of the strain-wave geared joint module 202B. The second housing 310 and the sub-housing 316 has the similar functionalities as that of the first housing 308.. The first housing 308 is configured to provide structural support and protection for the components of the electric motor. Further, the second housing 310 is mechanically coupled with the first housing 308 through a tight fit connection. The second housing 310 includes holes arranged with the first housing 308 to facilitate the passage of power and communication cables.
[0049] The electromagnetic brake 312 refers to a controllable braking element configured to apply a braking force and is operatively connected to the rotor shaft 302.. The electromagnetic brake 312 is configured to receive electrical signals from the control drive 318.. When activated, the electromagnetic brake 312 applies a braking force directly to the rotor shaft 302,, effectively stopping or holding its rotation. The function of the electromagnetic brake 312 is useful for maintaining the position of the plurality of joints during surgical procedures that require temporary immobilisation, such as tool exchange, system idle states, or safety shutdowns.
[0050] The encoder shaft 314 (interchangeably referred to as a rotary encoder), is a sensor that measures the rotation of a shaft (for example, the rotor shaft 302) and provides data on the position, speed, or direction of that shaft. In an implementation, the encoder shaft 314 is mechanically coupled to the rotor shaft 302 through a screw connection. In some implementations, the encoder shaft 314 may be secured using alternative coupling methods, such as key-slot arrangements, interference fits, or clamping mechanisms, depending on the alignment and structural requirements of the strain-wave geared joint module 202B.
[0051] The sub-housing 316 is mechanically coupled with the second housing 310 and houses the input encoder 326 and the output encoder 324.. The sub-housing 316 has two ends, with a first end fastened to the second housing 310 and a second end attached to the control drive 318 using dowel pins and screws. In another implementation, the sub-housing 316 may be connected to the second housing 310 and the control drive 318 using precision alignment features such as tongue-and-groove joints.
[0052] The control drive 318 refers to an integrated electronic unit mechanically and electrically connected to both the input encoder 326 and the output encoder 324.. The control drive 318 is configured to control the motor operation and acquire positional data from the input encoder 326 and the output encoder 324.. The control drive 318 manages and regulates the operation of the electric motor to achieve a specific desired output, such as controlling speed, torque, and direction of the electric motor. The control drive 318 includes an integrated encoder reader for both the input encoder 326 and the output encoder 324.. The control drive 318 processes the signals from both the input encoder 326 and the output encoder 324 to precisely control the motion of the strain-wave geared joint module 202B. The control drive 318 has a first end connected to the sub-housing 316 and a second end configured to interface with the adapter 322..
[0053] The output shaft 320 refers to the terminal rotating component of the strain-wave geared joint module 202B that delivers the final, gear-reduced torque output from the strain wave gear 328 to the robotic arm 112.. The output shaft 320 is operatively coupled to the strain wave gear 328 via a flange 330.. The output shaft 320 is configured to receive the rotary motion initially generated by the electric motor and subsequently converted by the strain wave gear 328 into a reduced-speed, high-torque output for precise actuation of the robotic arm 112.. To restrict unintended axial displacement of the output shaft 320 during operation, the adapter 322 is provided. The adapter 322 refers to element positioned at an outer end of the strain-wave geared joint module 202B. The adapter 322 functions as a mechanical stopper, thereby maintaining axial stability of the output shaft 320..
[0054] Encoders (for example, the input encoder 326 and the output encoder 324) are sensors that provide feedback about the position, speed, and direction of each movement of each strain-wave geared joint module. The feedback from the input encoder 326 and the output encoder 324 allows the control drive 318 to adjust the position, speed or direction of motion of the electric motor, ensuring precise and reliable movement of the robotic arm 112.. In the illustrated embodiment of FIG. 3, the output encoder 324 is affixed with the output shaft 320 and monitors the rotational position of the output shaft 320.. The input encoder 326 is affixed to the encoder shaft 314 and monitors the rotational position of the rotor shaft 302.. The input encoder 326 and the output encoder 324 provide feedback to the control drive 318 for precise motion control of the robotic arm 112..
[0055] The strain wave gear 328 refers to a high-precision, zero-backlash gear configured to convert high-speed, low-torque input from the rotor shaft 302 into low-speed, high-torque output at the output shaft 320.. The rotor shaft 302 transmits rotary motion generated by the electric motor to the strain wave gear 328 and then to the output shaft 320.. The strain wave gear 328 is configured to convert the high-speed, low-torque rotation of the electric motor into low-speed, high-torque output required for precise movement of the robotic arm 112..
[0056] FIG. 4 is a diagram illustrating the arrangement of bearings of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure. FIG. 4 is described in conjunction with the elements of FIGs. 1 to 3. With reference to FIG. 4, there is shown a cross-sectional view of the strain-wave geared joint module 202B highlighting the arrangement of bearings. The the strain-wave geared joint module includes a first bearing 402,, a second bearing 404,, a third bearing 406,, a fourth bearing 408,, a fifth bearing 410 and a sixth bearing 412..
[0057] The first bearing 402 refers to a bearing positioned between the strain wave gear 328 and the flange 330 that connects to the output shaft 320.. The first bearing 402 is housed in a projection of the flange 330 and provides a rotational interface between the strain wave gear 328 and the output shaft 320.. The first bearing 402 ensures smooth torque transfer from the strain wave gear 328 to the output shaft 320 while minimizing backlash and maintaining accurate positioning of the robotic arm 112.. In an implementation, the first bearing 402 is positioned to connect a harmonic gear assembly 414 to the flange 330 on the output shaft 320.. The harmonic gear assembly 414 refers to a high-precision, zero-backlash gear assembly configured to convert high-speed, low-torque rotational input from the rotor shaft 302 into low-speed, high-torque output suitable for controlled motion of the output shaft 420.. The first bearing 402 creates an interface between the strain wave gear 328 and the output shaft 320,, ensuring smooth torque transfer from the strain wave gear 328 to the output shaft 320.. The first bearing 402 maintains proper alignment between the strain wave gear 328 and the output shaft 320 while accommodating the radial forces generated during operation. Therefore, backlash reduces in the robotic surgical system 100,, thereby eliminating positioning errors that mitigates surgical accuracy during surgical procedures.
[0058] The second bearing 404 refers to a bearing installed in the first housing 308 and positioned around the rotor shaft 302.. The second bearing 404 is seated in a bearing housing located in the base part of the first housing 308 and is in tight fit with the rotor shaft 302.. In an implementation, the second bearing 404 and the third bearing 406 are fixed in the rotor shaft 302 by a tight fit with proper positioning by projecting the rotor shaft 302.. The third bearing 406 refers to a bearing positioned in the second housing 310 and surrounding a portion of the rotor shaft 302.. The third bearing 406 is housed in a third bearing seat in the second housing 310 and is connected to the rotor shaft 302 through a tight fit. The bearing seat (for example, the third bearing seat) refers to a recessed area configured to hold a bearing (for example, the first bearing 402,, the second bearing 404,, the third bearing 406,, the fourth bearing 408,, the fifth bearing 410 and the sixth bearing 412) in place. It ensures proper alignment and stable support of the bearing within the surrounding structure. The third bearing 406 further contributes to the precise alignment between the rotor magnet 304 and stator coil 306,, thereby providing efficient and consistent operation of the electric motor.
[0059] In an implementation, the second bearing 404 and the third bearing 406 are positioned to maintain coplanarity and concentricity between the rotor and the stator. The second bearing 404 and the third bearing 406 support the rotor shaft 302 and maintain accurate coplanarity and concentricity between the rotor magnet 304 and stator coil 306.. The proper alignment provided by the second bearing 404 prevents tilting between the rotor and stator, thereby reducing wide-angle errors that may lead to uneven magnetic fields and resulting torque fluctuations.
[0060] The second bearing 404 and the third bearing 406 are positioned at opposite ends of the rotor shaft 302 to maintain precise alignment between the rotor magnet 304 and the stator coil 306.. The placement of the second bearing 404 and the third bearing 406 prevents misalignment between the rotor magnet 304 and the stator coil 306.. Such misalignment may lead to wide-angle errors that distort the magnetic field distribution between the rotor and stator, causing torque instability and increased wear within the electric motor.
[0061] The fourth bearing 408 refers to a bearing installed on the encoder shaft 314.. The fourth bearing 408 is tightly fitted with the encoder shaft 314 and is positioned within the sub-housing 316.. The fourth bearing 408 is configured to maintain precise alignment of the encoder shaft 314 relative to the sub-housing 316..
[0062] The fifth bearing 410 refers to a bearing fixed in a fifth bearing seat in the encoder shaft 314.. The fifth bearing 410 interfaces with the output shaft 320 and is configured to provide a rotational support between the encoder shaft 314 and the output shaft 320.. The fifth bearing 410 prevents the output shaft 320 from shifting toward the flange 330 during assembly and operation of the strain-wave geared joint module 202B.
[0063] In an implementation, the fifth bearing 410 works in conjunction with the fourth bearing 408 to maintain a proper offset between the input encoder 326 and the output encoder 324 for measurement accuracy, thereby eliminating stack-up errors. In another implementation, the fourth bearing 408 and the fifth bearing 410 maintain precise coplanarity and concentricity between the input encoder 326 and the output encoder 324.. Maintaining coplanarity ensures that the sensing surfaces of the input encoder 326 and the output encoder 324 are aligned in the same plane. Coplanarity is useful for accurate positional sensing and signal consistency by the input encoder 326 and the output encoder 324.. Concentricity ensures that both the input encoder 326 and output encoder 324 rotate around the same central axis without any lateral offset. Concentricity is useful for minimizing measurement errors, ensuring smooth motion, and preventing mechanical wear of the input encoder 326,, the output encoder 324,, the encoder shaft 314 and the output shaft 320.. Precise coplanarity and concentricity between the input encoder 326 and the output encoder 324 ensure accurate position feedback. The fourth bearing 408 holds the input encoder 326 in a fixed radial and axial position. The fifth bearing 410 stabilises the output encoder 324 in the same manner as the fourth bearing 408..
[0064] The sixth bearing 412 refers to a bearing tightly fixed to the output shaft 320 and housed within the adapter 322.. The sixth bearing 412 serves as a mechanical stop to prevent unwanted axial movement of the output shaft 320 away from the flange 330.. In an implementation, the fifth bearing 410 and the sixth bearing 412 are positioned to ensure axial stability of the output shaft 320.. The fifth bearing 410 prevents the output shaft 320 from shifting toward the flange 330 during assembly and operation, while the sixth bearing 412,, housed within the adapter 322,, acts as a mechanical stop to prevent unwanted movement away from the flange.
[0065] In an implementation, the first bearing 402 and the sixth bearing 412 are positioned to provide axial stability to the input encoder 326 and the output encoder 324.. The first bearing 402 is mounted on the encoder shaft adjacent to the input encoder 326,, and the sixth bearing 412 is mounted on the output shaft 320 adjacent to the output encoder 324,, such that the first bearing and the second bearing constrain axial displacement of the encoder rings. The positioning of the first bearing 402 and the sixth bearing 412 maintains a fixed encoder-to-reader offset. The encoder-to-reader offset refers to the distance between the encoder ring and the integrated encoder reader. By keeping the encoder-to-reader offset value constant accurate signal detection is ensured. The encoder-to-reader offset reduces dependency on tight manufacturing tolerances and helps maintain consistent alignment of the input encoder 326 and the output encoder 324..
[0066] FIG. 5 is a diagram illustrating a cross-sectional view of a portion of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure. FIG. 5 is described in conjunction with the elements of FIGs. 1 to 4. With reference to FIG. 5, there is shown a portion of the strain-wave geared joint module 202B. The strain-wave geared joint module 202B includes the rotor shaft 302.. The rotor shaft 302 includes a first end 502,, and a second end 504.. In the illustrated embodiment of FIG. 5, the second bearing 404 and the third bearing 406 are fixed in the rotor shaft 302 by tight fit with proper positioning by projecting the rotor shaft 302.. In an implementation, the second bearing 404 and the third bearing 406 are fixed in the rotor shaft 302 by mechanical locking methods such as retaining rings or axial clamping features. In such implementations, the rotor shaft 302 is provided with bearing seats to ensure precise axial and radial positioning of the bearings for stable and concentric rotation. At the first end 502 of the rotor shaft 302,, the strain wave gear 328 is connected to the rotor shaft 302.. In the illustrated embodiment of FIG. 5, the strain wave gear 328 is connected to the rotor shaft 302 by the screwing of the first end 502 with a wave generator. In another embodiment, the strain wave gear 328 is connected to the rotor shaft 302 by a keyed interface that prevents rotational slippage between the rotor shaft 302 and the wave generator while still allowing for easy assembly and disassembly for maintenance purposes.
[0067] FIG. 6 is a diagram illustrating a cross-sectional view of the encoder shaft of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure. FIG. 6 is described in conjunction with the elements of FIGs. 1 to 5. With reference to FIG. 6, there is shown the cross-sectional view of the encoder shaft 314 including a first side 602,, a second side 604,, a third side 606 and a fourth side 608.. The first side 602 of the encoder shaft 314 is configured to interface with the second end 504 of the rotor shaft 302.. In an implementation, the first side 602 includes a threaded portion that accommodates a mechanical connection with the rotor shaft 302.. The threaded portion of the first side 602 enables the encoder shaft 314 to rotate in unison with the rotor shaft 302.. Furthermore, the first side 602 includes a mounting surface for the electromagnetic brake 312.. The electromagnetic brake 312 is secured between the rotor shaft 302 and the encoder shaft 314..
[0068] The second side 604 of the encoder shaft 314 is configured to accommodate the fourth bearing 408.. The fourth bearing 408 is positioned within the sub-housing 316 and provides lateral support for the encoder shaft 314.. The second side 604 includes a bearing seat that maintains proper alignment of the encoder shaft 314 within the sub-housing 316..
[0069] The third side 606 of the encoder shaft 314 features a bearing seat that houses the fifth bearing 410.. The fifth bearing 410 provides an interface between the encoder shaft 314 and the output shaft 320,, allowing the output shaft 320 to rotate relative to the encoder shaft 314.. The third side 606 prevents the output shaft 320 from shifting toward the strain wave gear 328 during operation.
[0070] The fourth side 608 of the encoder shaft 314 is configured to accommodate the input encoder 326.. The fourth side 608 includes a mounting surface that allows for the secure attachment of the input encoder 326.. The fourth side 608 is positioned at a specific distance from the output encoder 324 to maintain the proper offset required for optimal encoder reading by the control drive 318..
[0071] FIG. 7 is a diagram illustrating a cross-sectional view of another portion of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure. FIG. 7 is described in conjunction with the elements of FIGs. 1 to 6. With reference to FIG. 7, there is shown the cross-sectional view of the strain wave gear 328 operatively coupled to the flange 330 to receive and transmit the reduced-speed, high-torque output from the strain wave gear 328 to the output shaft 320.. In the illustrated embodiment of FIG. 7, the strain wave gear 328 includes a wave generator 702 operatively connected to the rotor shaft 302,, a wave generator bearing 704.. The strain wave gear 328 further includes a flex spline 706 in contact with the wave generator 702 via the wave generator bearing 704 and a circular spline 708 in contact with the flex spline 706.. Furthermore, the output shaft 320 is connected to the flex spline 706 via the flange 330.. Additionally, the flange 330 includes an inner core area 710,, a middle area 712 and an outer peripheral area 714..
[0072] The wave generator 702 is the driving component that transfers rotation from the rotor shaft 302 to the flex spline 706 of the strain wave gear 328.. The wave generator 702 is an elliptical component connected to the rotor shaft 302 at the first end 502.. The wave generator 702 rotates at the same speed as the rotor shaft 302 and serves as a driving component of the strain wave gear 328.. The elliptical shape of the wave generator 702 is configured to deform the flex spline 706..
[0073] The wave generator bearing 704 is positioned between the wave generator 702 and the flex spline 706.. The wave generator bearing 704 allows the wave generator 702 to rotate smoothly within the flex spline 706 while transferring the elliptical deformation pattern to the flex spline 706.. The wave generator bearing 704 reduces friction between the wave generator 702 and the flex spline 706.. The reduction in friction between the wave generator 702 and the flex spline 706 ensures suitable power transmission from the rotor shaft 302 to the flex spline 706..
[0074] The flex spline 706 is a thin-walled, flexible cylindrical component with external teeth at one end. The flex spline 706 is deformed into an elliptical shape by the wave generator 702 via the wave generator bearing 704.. The deformation causes the external teeth of the flex spline 706 to engage with the internal teeth of the circular spline 708 at two engagement points approximately 180 degrees apart. As the wave generator 702 rotates, the two engagement points also rotate, causing the flex spline 706 to rotate at a reduced speed relative to the wave generator 702.. In an implementation, the flex spline 706 includes a base flex spline part, a cup wall part, and a toothed wall part; and the circular spline 708 in contact with the toothed wall part of the flex spline 706..
[0075] The circular spline 708 is a rigid ring with internal teeth that engage with the external teeth of the flex spline 706.. The circular spline 708 is fixed to the first housing 308 and remains stationary during operation. Additionally, the difference in the number of teeth between the flex spline 706 and the circular spline 708 determines the reduction ratio of the strain wave gear 328,, allowing for high torque output at low rotational speeds. For example, if the circular spline 708 has 202 teeth and the flex spline 706 has 200 teeth, each full rotation of the wave generator 702 causes the flex spline 706 to rotate by only two teeth relative to the circular spline 708.. Therefore, resulting in a reduction ratio of 100:1. In other words, the output shaft 320 rotates once for every 100 rotations of the input shaft 320.. The reduction ratio of 100:1 enables the strain wave gear 328 to deliver increased torque at a reduced output speed, ideal for robotic applications.
[0076] The flange 330 connects the flex spline 706 to the output shaft 320.. The inner core area 710 of the flange 330 is where the flange 330 and the output shaft 320 are fastened together. In an implementation, the flange 330 and the output shaft 320 are fastened together through a threaded connection. In another implementation, the flange 330 and the output shaft 320 are fastened together through an interference fit. The connection between the flange 330 and the output shaft 320 ensures that the rotational motion of the flex spline 706 is transferred to the output shaft 320 without slippage.
[0077] The middle area 712 of the flange 330 includes a projection that houses the first bearing 402.. The first bearing 402 supports the flange 330 and maintains proper alignment between the flex spline 706 and the output shaft 320.. The first bearing 402 enables smooth rotation of the flange 330 relative to the strain wave gear 328..
[0078] The outer peripheral area 714 of the flange 330 is fixed to the flex spline 706,, configured to transmit the rotational motion from the flex spline 706 to the flange 330 and subsequently to the output shaft 320.. As the flex spline 706 rotates due to the action of the wave generator 702,, the flange 330 and the output shaft 320 rotate at the same reduced speed, delivering high torque output for precise movement of the robotic arm 112..
[0079] FIG. 8 is a diagram illustrating a cross-sectional view of yet another portion of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure. FIG. 8 is described in conjunction with the elements of FIGs. 1 to 7. With reference to FIG. 8, there is shown the cross-sectional view of the strain-wave geared joint module of the robotic arm 112 including the first housing 308,, the second housing 310,, the sub-housing 316 and the output shaft 320.. In the illustrated embodiment of FIG. 8, the first housing 308 includes a first side 802 and a second side 804.. The second housing 310 includes a first end 806 and a second end 808.. Further, the sub-housing 316 includes a first end 810 and a second end 812.. Furthermore, the output shaft 320 includes a first side 814,, a second side 816,, a third side 818 and a fourth side 820..
[0080] The first side 802 of the first housing 308 forms a motor base part configured to connect to the outer circular spline 708 of the strain wave gear 328.. In an implementation, the first side 802 includes mounting features for securing the circular spline 708,, ensuring the circular spline 708 remains stationary during operation. In another implementation, the circular spline 708 may be integrated directly into the first housing 308 or fixed using dowel pins, threaded fasteners, or adhesive bonding to achieve a rigid, non-rotating connection with the structural frame of the strain-wave geared joint module 202B. The first side 802 also includes a bearing housing where the second bearing 404 configured to support the rotor shaft 302 is placed.
[0081] The second side 804 of the first housing 308 is configured to interface with the first end 806 of the second housing 310.. In an implementation, the second side 804 is configured to engage the second housing 310 through a tight-fit connection that maintains positional alignment between the second side 804 and the second housing 310 during assembly and operational use. In another implementation, the second side 804 may be connected to the second housing 310 using fastening elements such as screws or bolts in combination with dowel pins to provide both axial retention and anti-rotation locking. In yet another implementation, the second side 804 may incorporate a key-slot or tongue-and-groove interface with the second housing 310 to facilitate self-aligning assembly and improve mechanical stability under dynamic loading conditions. Additionally, the second side 804 contains holes arranged to allow for the passage of power and communication cables through the structure of the first housing 308..
[0082] The second end 808 of the second housing 310 interfaces with the first end 810 of the sub-housing 316.. In an implementation, the second end 808 is configured to secure the sub-housing 316 in a fixed position, thereby maintaining accurate alignment of the encoder shaft 314.. Furthermore, the second end 808 houses the third bearing seat for the third bearing 406 supporting the rotor shaft 302,, ensuring proper alignment between the electric motor and encoder sections of the strain-wave geared joint module 202B.
[0083] The second end 812 of the sub-housing 316 is configured to interface with the control drive 318.. In an implementation, the second end 812 includes features for attachment using dowel pins and screws, ensuring precise alignment between the sub-housing 316 and the control drive 318.. The first side 814 of the output shaft 320 is configured to receive and securely position the flange 330 in a fixed arrangement. In an implementation, the first side 814 of the output shaft 320 is configured for secure attachment to the flange 330,, achieved through a threaded interface, interference fit to ensure rigid and stable coupling during torque transmission. The connection between the output shaft 320 and the flange 330 ensures efficient transfer of torque from the strain wave gear 328 through the flange 330 to the output shaft 320..
[0084] The second side 816 of the output shaft 320 is configured to interface with the fifth bearing 410.. Thereby ensuring smooth rotation of the output shaft 320 relative to the encoder shaft 314 while preventing axial movement toward the strain wave gear 328.. The third side 818 of the output shaft 320 serves as a seat for the output encoder 324.. The third side 818 is configured to ensure proper positioning of the output encoder 324 relative to the control drive 318 for accurate position feedback. The fourth side 820 of the output shaft 320 interfaces with the sixth bearing 412.. The fourth side 820 is configured to provide proper support for the sixth bearing 412.. The fourth side 820 allows the sixth bearing 412 to act as a mechanical stop, preventing unwanted axial movement of the output shaft 320 away from the flange 330 during operation.
[0085] FIG. 9 is a diagram illustrating a cross-sectional view of the control drive of the strain-wave geared joint module of the surgical robotic arm, in accordance with an embodiment of the present disclosure. FIG. 9 is described in conjunction with the elements of FIGs. 1 to 8. With reference to FIG. 9, there is shown the cross-sectional view of the strain-wave geared joint module 202B including various components of the control drive 318.. In the illustrated embodiment of FIG. 8, the various components of the control drive 318 includes a first end 902 and a second end 904.. The first end 902 of the control drive 318 is configured to interface with the second end 812 of the sub-housing 316.. In an implementation, the first end 902 includes mounting features that allow for attachment to the sub-housing 316 using dowel pins and screws. The first end 902 houses an integrated encoder reader configured to read both the input encoder 326 and the output encoder 324.. The second end 904 of the control drive 318 interfaces with the adapter 322 that houses the sixth bearing 412.. The second end 904 provides structural support for the adapter 322 and ensures proper alignment of the output shaft 320 with the control drive 318.. The second end 904 includes features for securing the adapter 322,, maintaining the axial stability of the output shaft 320 during operation.
[0086] In operation, a surgeon controls the movement of the robotic arm 114 by providing input through the surgeon console 130.. In an implementation, the inputs through the surgeon console 130 are captured by high-precision sensors and translated into digital control signals. The high-precision sensors used in the surgeon console 130 refer to high-precision input detection devices configured to capture the hand, finger, or wrist movements of the surgeon and convert them into electrical signals. In an implementation, the high-precision sensors may include force sensors, position sensors, inertial measurement units (IMUs), optical encoders, or Hall effect sensors. For example, force sensors may detect grip pressure, while optical encoders may track the angular displacement of the control knobs or joysticks of the surgeon. In another implementation, 3-axis IMUs may be used to detect orientation and motion, contributing to precise spatial control.
[0087] Upon receiving the digital control signals, the control drive 318 initiates actuation at the targeted joints of the robotic arm 114.. For example, the control drive 318 initiates actuation at the first joint 202A. The actuation begins when the control drive 318 generates electrical signals based on the commands of the surgeon and feedback from the input encoder 326 and the output encoder 324.. The electrical signals are transmitted to the stator coil 306,, creating a controlled electromagnetic field.
[0088] The electromagnetic field produced by the stator coil 306 interacts with the permanent magnets of the rotor magnet 304,, generating electromagnetic torque that causes the rotor to rotate at a precisely controlled speed. The rotational motion of the rotor is directly transferred to the rotor shaft 302.. The second bearing 404 and third bearing 406 maintain precise coplanarity and concentricity between the rotor magnet 304 and stator coil 306,, preventing wide-angle errors.
[0089] The rotor shaft 302 is mechanically coupled to the wave generator 702.. As the wave generator 702 rotates, the flex spline 706 undergoes a cyclic elastic deformation. The cyclic elastic deformation forces the external teeth of the flex spline 706 to engage with the internal teeth of the circular spline 708.. Due to the difference in tooth count between the flex spline 706 and the circular spline 708,, each complete rotation of the wave generator 702 advances the flex spline 706 by only a few teeth relative to the circular spline 708,, creating a reduction ratio (for example, approximately ranging between 50:1 and 160:1).
[0090] The reduced-speed, high-torque rotational output from the flex spline 706 is transferred to the flange 330 at the outer peripheral area 714.. The flange 330 transmits the reduced-speed, high-torque rotational output to the first joint 202A. The first bearing 402,, positioned between the strain wave gear 328 and the flange 330,, ensures smooth torque transfer while minimizing backlash.
[0091] The input encoder 326 continuously monitors the rotational position and velocity of the rotor shaft 302 via the encoder shaft 314,, while the output encoder 324 simultaneously tracks the position of the output shaft 320.. The input encoder 326 and the output encoder 324 provide real-time feedback at high resolution to the control drive 318 creating a continuous feedback loop. The control drive 318 processes the feedback from the input encoder 326 and the output encoder 324 to detect and compensate for any backlash. Based on the continuous feedback loop, the control drive 318 dynamically adjusts the electrical signals to the stator coil 306,, modifying torque output as needed to maintain precise positioning of the robotic arm 114.. The continuous feedback loop enables the robotic arm 114 to achieve sub-millimeter positioning accuracy even under varying load conditions, providing the surgeon with the precise control suitable for delicate surgical procedures while ensuring patient safety through controlled, deliberate movements.
[0092] FIG. 10 is a flowchart illustrating a method for operating the robotic surgical system, in accordance with an embodiment of the present disclosure. FIG 10 is described in conjunction with elements from FIGs. 1 to 9. With reference to FIG. 10, there is shown a flowchart illustrating a method 1000 for operating the robotic surgical system 100.. The method 1000 includes steps 1002 to 1016.
[0093] At step 1002, the method 1000 includes receiving surgeon inputs at the surgeon console 102.. The surgeon inputs are detected by the high-precision sensors within the surgeon console 102 and converted into digital signals. The high-precision sensors utilise high-resolution encoders to track movements with precision, ensuring that the robotic arm 112 accurately follows the intended actions of the surgeon.
[0094] At step 1004, the method 1000 includes processing the surgeon inputs to generate control signals. The processing of the surgeon inputs occurs in a central processing unit within the robotic surgical system 100.. The central processing unit is configured to translate the raw input data from the surgeon console 102 into specific commands. The processing includes scaling the movements of the surgeon to appropriate ranges for the robotic arms, filtering out unintentional tremors or jitters. Furthermore, safety constraints are applied to prevent potentially harmful movements. The control signals are generated at a high frequency to ensure smooth, real-time response of the robotic arm 112.. The control signals contain information about the desired position, velocity, and acceleration for each joint in the robotic arm 112..
[0095] At step 1006, the method 1000 includes transmitting the control signals to the patient-side cart 110 comprising the plurality of robotic arms. The control signals are transmitted via a high-speed, low-latency communication network that connects the processing unit to the patient-side cart. The transmission of the control signals utilises error-correction protocols to ensure signal integrity throughout the surgical procedure. The patient-side cart 110 receives control signals through receivers that route the appropriate commands to each robotic arm of the plurality of robotic arm. The transmission of the control signals incorporates redundancy measures to maintain uninterrupted operation.
[0096] At step 1008, the method 1000 includes displaying images from a surgical site on the vision cart 120.. Endoscopic cameras at the surgical site capture stereoscopic images that are processed by the vision cart 120.. The vision cart 120 performs colour correction, contrast enhancement, and digital stabilization to improve the image quality. The improved images are displayed on the stereoscopic display system 134 positioned at the surgeon console 102,, providing the surgeon with a clear, magnified view of the surgical site.
[0097] At step 1010, the method 1000 includes operating at least one robotic arm of the plurality of robotic arms by rotating the rotor shaft 302 connected to the strain wave gear 328.. The control signals activate the electric motor in the strain-wave geared joint module 202B, causing the rotor magnet 304 to rotate within the stator coil 306.. The rotation of the rotor magnet 304 drives the rotor shaft 302.. The speed of rotation is monitored by the input encoder 326 attached to the encoder shaft 314,, providing feedback to the control drive 318 for accurate motion control. The electromagnetic brake 312 may be engaged or disengaged as needed to hold position or allow movement of the joint.
[0098] At step 1012, the method 1000 includes causing a flex spline of the strain wave gear to move relative to the circular spline during rotation. As the rotor shaft 302 rotates, it drives the wave generator 702 of the strain wave gear 328.. The elliptical shape of the wave generator 702 deforms the flex spline 706 through the wave generator bearing 704.. The deformation of the flex spline 706 causes the external teeth of the flex spline 706 to engage with the internal teeth of the circular spline 708 at diametrically opposite points. As the wave generator 702 rotates, the points of engagement between the flex spline 706 and the circular spline 708 travel around the inner circumference of the circular spline 708 creating progressive motion that drives the flex spline 706 in the opposite direction at a reduced speed.
[0099] At step 1014, the method 1000 includes transferring torque to the output shaft 320.. The rotation of the flex spline 706 is transferred to the flange 330.. The flange 330 is mechanically coupled to the output shaft 320 causing the output shaft 320 to rotate at the same reduced speed as the flex spline 706 but with higher torque. The high-torque, low-speed rotation is suitable for precise control of the robotic arm 112 during surgical procedures. The output encoder 324 monitors the rotational position of the output shaft 320,, providing feedback to the control drive 318 for closed-loop position control.
[0100] At step 1016, the method 1000 includes utilising a plurality of bearings to maintain precise alignment between components. The six bearings (i.e. the first bearing 402,, the second bearing 404,, the third bearing 406,, the fourth bearing 408,, the fifth bearing 410,, and the sixth bearing 412) are positioned throughout the strain-wave geared joint module. The six bearings work together to maintain precise alignment of the rotor shaft 302,, the encoder shaft 314,, and the output shaft 320.. The precise alignment of the rotor shaft 302,, the encoder shaft 314,, and the output shaft 320 ensures stable and accurate rotational motion across the motor, encoder, and gear assemblies.
[0101] The steps 1002 to 1016 are only illustrative, and other alternatives can also be provided where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.
[0102] Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. The word "exemplary" is used herein to mean "serving as an example, instance or illustration". Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and/or to exclude the incorporation of features from other embodiments. The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments". It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as suitable in any other described embodiment of the disclosure. , C , Claims:We Claim:
1. A robotic surgical system (100) comprising:
a patient-side cart (110) comprising a plurality of robotic arms;
a surgeon console (130) configured to receive inputs from a surgeon to control the plurality of robotic arms;
a vision cart (120) configured to process and display images from a surgical site;
wherein at least one robotic arm of the plurality of robotic arms comprises a strain-wave geared joint module (202B), the strain-wave geared joint module (202B) comprising:
a rotor shaft (302);
a strain wave gear (328) connected to the rotor shaft (302);
an electric motor comprising a stator and a rotor;
an output shaft (320) operatively connected to the strain wave gear (328);
a plurality of bearings; and
an input encoder (326) and an output encoder (324), wherein the plurality of bearings are strategically positioned to maintain precise alignment between components, reduce wide-angle errors that can lead to uneven magnetic fields and torque fluctuations, reduce stack-up errors during multi-part assembly, and ensure axial stability of the output shaft (320), thereby providing a compact, precise, and durable joint module for the robotic arm (112).
2. The robotic surgical system (100) of claim 1, wherein the strain-wave geared joint module (202B) further comprises a housing comprising a motor housing (308) and an encoder casing (316), and wherein the input encoder (326) and the output encoder (324) are positioned within the encoder casing (316) to maintain accurate measurement and control of the strain-wave geared joint module (202B).
3. The robotic surgical system (100) of claim 1, wherein the strain wave gear (328) comprises: a wave generator (702) connected to the rotor shaft (302); a wave generator bearing (704); a flex spline (706) in contact with the wave generator (702) via the wave generator bearing (704); and a circular spline (708) in contact with the flex spline (706); wherein the output shaft (320) is connected to the flex spline (706) via a flange (330).
4. The robotic surgical system (100) of claim 1, wherein the plurality of bearings comprises six bearings including: a first bearing (402) positioned to connect a harmonic gear assembly (414) to the flange on the output shaft (320); a second bearing (404) and a third bearing (406) positioned to maintain coplanarity and concentricity between the rotor and the stator; a fourth bearing (408) and a fifth bearing (410) positioned to maintain coplanarity and concentricity between the input encoder (326) and the output encoder (324); and a fifth bearing (410) and a sixth bearing (412) positioned to ensure axial stability of the output shaft (320).
5. The robotic surgical system (100) of claim 4, wherein: the first bearing (402) is fixed in a bearing housing in a base part of the motor housing (308) and is in tight fit with the rotor shaft (302); the second bearing (404) is connected to the rotor shaft (302) and is housed in a brake mount through a bearing seat; the third bearing (406) is tightly fitted with an encoder shaft (314) connected to the rotor shaft (302); the fourth bearing (408) is fixed in a bearing seat of the encoder shaft (314); the fifth bearing (410) connects the strain wave gear (328) to the flange (330) on the output shaft (320); and the sixth bearing (412) is tightly fixed to the output shaft (320) and is housed in an adapter (322) that acts as a mechanical stopper.
6. The robotic surgical system (100) of claim 1, wherein the strain-wave geared joint module (202B) further comprises: an encoder shaft (314) connected to the rotor shaft (302), wherein the input encoder (326) is affixed to the encoder shaft (314); an electromagnetic brake (312) connected to the rotor shaft (302); and a control drive (318) connected to the encoder casing (316) and including an integrated encoder reader for reading both the input encoder (326) and output encoder (324).
7. A method (1000) for operating a robotic surgical system (100), the method (1000) comprising:
receiving surgeon inputs at the surgeon console (130);
processing the surgeon inputs to generate control signals;
transmitting the control signals to a patient-side cart (110) comprising a plurality of robotic arms;
displaying images from a surgical site on a vision cart (120);
operating at least one robotic arm of the plurality of robotic arms by: rotating a rotor shaft (302) connected to a strain wave gear (328);
causing a flex spline (706) of the strain wave gear (328) to move relative to a circular spline (708) during rotation;
transferring torque to an output shaft (320); and
utilizing a plurality of bearings to maintain precise alignment between components, wherein the plurality of bearings provide stability and precision by preventing component tilting, reducing wide-angle errors, eliminating stack-up errors during multi-part assembly, and strengthening structural integrity of the strain-wave geared joint module (202B), thereby providing higher precision control and increased durability for robotic surgical procedures.
8. The method (1000) of claim 7, further comprising: maintaining precise alignment between a rotor magnet (304) and a stator coil (306) of an electric motor using a first set of bearings; maintaining precise alignment between input encoder (326) and output encoder (324) using a second set of bearings; ensuring axial stability of the output shaft (320) using a third set of bearings; and reading position data from the input encoder (326) and the output encoder (324) using an integrated encoder reader in a control drive (318).
9. The method (1000) of claim 7, further comprising: rotating a wave generator (702) connected to the rotor shaft (302); transferring torque from the flex spline (706) to the output shaft (320) via a flange; and activating an electromagnetic brake (312) connected to the rotor shaft (302) to stop rotation of the rotor shaft (302).
10. A robotic arm (112) for a robotic surgical system (100), the robotic surgical system (100) comprising a patient-side cart (110), a surgeon console (130), and a vision cart (120), the robotic arm (112) comprising:
a strain-wave geared joint module (202B) comprising:
a housing;
a rotor shaft (302);
a strain wave gear (328) connected to the rotor shaft (302);
an electric motor;
an output shaft (320) operatively connected to the strain wave gear (328);
a plurality of bearings; and
an input encoder (326) and an output encoder (324);
a control drive (318) connected to the housing; and
a surgical instrument interface configured to connect a surgical instrument (140) to the robotic arm (112), wherein the plurality of bearings are strategically positioned to form a reduced stack-up chain that decreases manufacturing tolerance requirements while ensuring concentricity and coplanarity among components, and wherein the control drive (318) reads both input encoder (326) and output encoder (324) to maintain a compact and efficient design that provides precise position control and improved durability compared to conventional joint modules.
11. The robotic arm (112) of claim 10, wherein the plurality of bearings comprises six bearings including: a first bearing (402) positioned to connect a harmonic gear assembly (414) to the flange (330) on the output shaft (320); a second bearing (404) and a third bearing (406) positioned to maintain coplanarity and concentricity between the rotor and the stator; a third bearing (406) and a fourth bearing (408) positioned to maintain coplanarity and concentricity between the input encoder (326) and the output encoder (324); and a fifth bearing (410) and a sixth bearing (412) positioned to ensure axial stability of the output shaft (320).
12. The robotic arm (112) of claim 10, wherein: the housing comprises a motor housing (308) and an encoder casing (316); the rotor shaft (302) comprises a first end (502) and a second end (504); the strain wave gear (328) is connected to the first end (502) of the rotor shaft (302); and the control drive includes an integrated encoder reader for reading both the input encoder (326) and output encoder (324).
13. The robotic arm (112) of claim 10, wherein the strain wave gear (328) comprises: a wave generator (702) connected to the rotor shaft (302); a wave generator bearing (704); a flex spline (706) in contact with the wave generator (702) via the wave generator bearing (704), the flex spline (706) comprising a base flex spline part, a cup wall part, and a toothed wall part; and a circular spline in contact with the toothed wall part of the flex spline (706).
14. The robotic arm (112) of claim 10, wherein the electric motor comprises a stator coil (306) affixed to an inner wall of the motor housing (308) and a rotor magnet (304) affixed to the rotor shaft (302), and wherein the input encoder (326) and output encoder (324) are positioned within the encoder casing (316).
15. The robotic arm (112) of claim 10, further comprising: an encoder shaft (314) connected to the rotor shaft (302); and an electromagnetic brake (312) connected to the rotor shaft (302); wherein the encoder shaft (314) has the input encoder (326) affixed to encoder shaft (314), and the output shaft (320) has the output encoder (324) affixed to a projected circular part of the output shaft (320).