Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed

Field of the invention

[0001] The present invention relates to a robotic arm to provide multi-axial motion.

[0002] Background of the invention

[0003] In robotics, transmission can be classified in two categories, mainly, mobile robots, that is the movement of the robot from one location to another (using wheels, propellers in drones etc.) and the bending robots where parts of the robot are bent to achieve specific functions that may imitate the movement of an arm, claw, fingers etc.

[0004] A robotic arm, like a human arm uses multiple links in series and joints, allowing it to function in a manner similar a human arm. The number of joints in a robotic arm can vary widely depending on its design and intended application. A common configuration for industrial robotic arms is six joints, referred to as a 6-DOF (Degrees of Freedom) robotic arm. This means the arm can articulate and move in six different ways, providing flexibility in reaching and manipulating objects in three-dimensional space. It is important to note that the joints in such arms are hinge joints that are each actuated by different motors separately. The use of six joints typically requires six links as well as six motors.

[0005] The limitation of the hinge joint is that it can transmit force in only one plane. If an external force comes from a direction different from the intended direction of motion of the hinge joint, there would be no elastic deformation in that joint. To solve this problem, the hinge joints can be replaced by ball and socket joints, which have a higher degree of freedom per joint. This allows for each joint to freely bend in any direction in response to an external force, hence decreasing the resistance to bending, thereby making it a true soft robotic arm. Actuation of ball and socket joints is difficult and still remains a challenge in robotics. The existing systems use electromagnetism (in a gear mechanism) and spherical gears to replicate motion of ball and socket joint.

[0006] The present invention proposes a new actuation mechanism for a ball and socket joint, giving it soft robotic characteristics. The present invention uses pulley systems around a ball and socket joint. The same can be implemented merely by four pulleys in two belt drives and two motors.

Brief description of the accompanying drawings
[0007] An embodiment of the invention is described with reference to the following accompanying drawings:
[0008] Figure 1 depicts a robotic arm to provide a multi-axial motion.

Detailed description of the drawings:

[0009] The present invention will now be described by way of example, with reference to accompanying drawings. Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations, and fragmentary views. In predetermined instances, details which are not necessary for an understanding of the present invention, or which render other details difficult to perceive may have been omitted.
[0010] Referring to Figure (1), the same depicts a robotic arm to provide a multi-axial motion. 1A represents the front view of the robotic arm and 1B represents two lateral views of the robotic arm. Said robotic arm comprises a ball-and-socket region. The ball and socket region comprises a ball (30) rotatably fixed between an upper plate (30a) and a lower plate (30b), said upper and lower plate (30b) are connected by an elastic means (31). Said elastic means (31) may be any material exhibiting elastic properties so as to provide a desired flexibility to the robotic arm. According to the present disclosure, said material may be (but not limited to) a spring.

[0011] According to an embodiment of the present disclosure, the robotic arm comprises a first pulley system comprising a first upper-pulley (10a) and a first lower-pulley(10b). Said first upper and lower pulleys are connected through a first belt drive (10c). Said first lower-pulley is rotatably fixed on the lower plate (30b).

[0012] The robotic arm comprises a second pulley system perpendicular to the first pulley system. Said second pulley system comprises a second upper-pulley (20a) and a second lower-pulley (20b) connected through a second belt drive (20c). Said second upper-pulley (20a) is rotatably fixed on the upper plate (30a).

[0013] It is to be understood that belt-drive includes ropes, belts and other means to drive the pulley. The same is not to be construed as limiting the scope of the invention.

[0014] According to an embodiment in the present disclosure, the order of arrangement of each the individual pulleys of the present invention may be the first upper pulley (10a) above second upper pulley (20a) (fixed on the upper plate (30a)), then the first lower pulley (10b) (fixed on the lower plate (30b)) above the second lower pulley (20b).

[0015] Said first pulley system actuates to provide motion to the robotic arm along a first plane and the second pulley system actuates to provide motion to the robotic arm along a second plane perpendicular to the first plane. Said ball and socket region and the said first and second pulley system comprise a common central axis (50).
[0016] 1C depicts a resultant direction of motion (represented by longer arrow (60)) of the robotic arm when the first and second pulley systems are actuated together. The multi-axial motion is provided to a section (40) of robotic arm around the common central axis (50). Said section (40) comprises the first upper pulley (10a), the second upper pulley (20a) and the upper plate (30a). This section (40) can be rotated across all planes (360 degrees) around the central axis.

[0017] The first upper pulley (10a) and the second lower-pulley(20b) are connected to at least one motor (11, 21) to actuate at least one of the first and second pulley system. According to an embodiment, a first motor (11) may be connected with the first upper pulley (10a) and a second motor (21) may be connected to the second lower pulley (20b). Motion along a resultant-axis (60) is provided to the robotic arm when the first and the second pulley system are actuated together. Said resultant-axis (60) is determined based on a first torque provided by the at least one motor to the first upper pulley (10a) and a second torque provided by the at least one motor to the second lower pulley (20b).

[0018] The working of the said robotic arm is now described further. Considering second pulley system, if the second lower pulley (20b) (to which motor is connected) is actuated in a clockwise manner, then a magnitude of torque (see 1B, right side of the drawing) will act on the second upper pulley (20a) and as a result, the section (40) the first upper pulley (10a), the second upper pulley (20a) and the upper plate (30a)) will bend right and backwards (see 1B, right side of the drawing). Similarly, in the first pulley system, if the first upper pulley (10a) is rotated in a counter-clockwise manner (actuated through motor), a second magnitude of torque will be applied on the first lower pulley (10b) (Direction of torque represented by semi-circular arrow in 1B, left side of the drawing). Since the first lower pulley (10b) is fixed, it will cause the section (40) to bend right and forward(direction indicated by bent arrow in 1B, left side of the drawing).
[0019] When the two drive belts (first and second belt drive (10c, 20c)) are actuated separately, the bending of the section (40) takes place only in the corresponding planes of the belts (first and second planes). If both the belts are actuated together, the section (40) will bend in the resultant direction depending on the actuation of both belt-drives (first and second) – as shown in figure 1C.

[0020] Due to the elastic nature of the belt-drives and the springs connecting the two plates in the ball and socket region, if the section (40) experiences any external force, it will bend in the direction of that force, due to the stretching of the belts. Once the force is removed, the upper links will return to its original position – making it a soft joint. Since the proposed robotic arm has a ball and socket joint, the external force can be in any direction and the joint will still bend, unlike a hinge joint for which the force needs to be in a specific plane.
, Claims:We Claim:
1. A robotic arm to provide a multi-axial motion, said robotic arm comprising:

- a ball-and-socket region comprising a ball (30) rotatably fixed between an upper plate (30a) and a lower plate (30b), said upper and lower plate (30b) connected by an elastic means (31),
- a first pulley system comprising a first upper-pulley and a first lower-pulley connected through a first belt drive (10c), said first lower-pulley rotatably fixed on the lower plate (30b),
- a second pulley system perpendicular to the first pulley system, said second pulley system, comprising a second upper-pulley and a second lower-pulley connected through a second belt drive (20c), said second upper-pulley rotatably fixed on the upper plate (30a),
wherein,
said first pulley system actuates to provide motion to the robotic arm along a first plane and the second pulley system actuates to provide motion to the robotic arm along a second plane perpendicular to the first plane.

2. The robotic arm as claimed in Claim 1, wherein said ball and socket region and the said first and second pulley system comprise a common central axis (50).

3. The robotic arm as claimed in claimed in claim 2, wherein, the multi-axial motion is provided to a section (40) of robotic arm around the common central axis .

4. The robotic arm as claimed in Claim 3, wherein, said section (40) comprises the first upper pulley (10a), the second upper pulley (20a) and the upper plate (30a).

5. The robotic arm as claimed in Claim 1, wherein, the first upper pulley (10a) and the second lower-pulley are connected to at least one motor to actuate at least one of the first and second pulley system.

6. The robotic arm as claimed in Claim 1, wherein, motion along a resultant-axis (60) is provided to the robotic arm when the first and the second pulley system are actuated together.

7. The robotic arm as claimed in Claim 4, wherein, said resultant-axis (60) is determined based on a first torque provided by the at least one motor to the first upper pulley (10a) and a second torque provided by the at least one motor to the second lower pulley (20b).