DESC:TECHNICAL FIELD

Embodiments of the present disclosure are related, in general to gait analysis and more particularly, but not exclusively to a method and system for facilitating gait analysis of a subject.
BACKGROUND
Gait is a pattern of human locomotion and is unique to individual due to one's specific muscular-skeletal bio-mechanism. Generally, neuropathy and diseases of the musculoskeletal system may cause the problem in walking. From the medical perspective, the disease changes the coordination, harmonization and interaction of the muscle, skeleton, nerves, joints etc, and thus influences the human’s gait. Gait analysis is vital from the view of its capacity as an indicator for neuromuscular disorders. Hence, evaluation of human gait has become a vital factor in the field of medicine, rehabilitation, sports and the like. Human body kinematics may be useful to aid athletes in the improvement of their performance, and to evaluate the efficiency of prescribed therapies and the rehabilitation of patients. Particularly, knee joint motion assessment is vital as sufficient range of motion of the knee joint is necessary for performance of daily activities, and knee joint motion evaluation may provide valuable information regarding diseases like knee osteoarthritis along with assessment of the efficacy of surgical interventions like total knee arthroplasty. Other aspect such as forefoot load may also be useful in gait analysis in diagnosis of foot related disorders such as arthritis, plantar fasciitis, and diabetic ulceration.
Existing techniques include knee angle measurement by either handheld devices or wearable devices. Range of motion of knee joint in clinical diagnostics is carried out primarily by handheld goniometers. Further, inertial magnetic unit, accelerometer, gyroscope, monometer and Micro-Electro Mechanical Systems (MEMS) based devices are also developed for knee angle measurements. However, the use of these devices is limited by the fluctuating offsets with drawbacks of electrical devices. Other methods include use of optical methodologies like camera and reflective markers. Infrared (IR) sensors are also employed for knee angle measurement. The complexity of these systems along with obscurity of images procured, cost and the like prove as limitations for efficient gait analysis. Therefore, it is essential to develop an easy-to-use wearable knee angle measurement device for all variants of exercises performed by the human. On the other hand, techniques for forefoot load measurement includes use of multiple sensors in different orientations for each foot, to acquire plantar strain distribution. The insole types of devices with sensors embedded inside the sole of footwear are preferred, as the devices are wearable and portable which is advantageous for continuous tracking of plantar force when the human is in motion. Existing insole plantar force measurement systems include use of various sensor methodologies like piezo resistive pressure sensors, capacitive pressure sensors, bend sensors and the like. However, these devices have inherent disadvantages like variation in strain acquisition with respect to direction of force application on the footwear, the use of electric power for the sensor element and the like.
The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

SUMMARY
Disclosed herein is a method for facilitating gait analysis of a subject. The method comprises steps of obtaining a knee angle measurement data of at least one of a left knee and a right knee of the subject using at least one of a first Knee Angle Measurement Device (KAMD) and a second knee angle measurement device (KAMD) respectively. The first KAMD is attached to the left knee of the subject and the second KAMD is attached to the right knee of the subject. The method further comprises obtaining a forefoot load measurement data of at least one of a left forefoot and a right forefoot of the subject using at least one of a first forefoot load measurement device (FLMD) and a second FLMD respectively. The first FLMD is attached to the left forefoot of the subject and the second FLMD is attached to the right forefoot of the subject. The method further comprises receiving, by a gait analysis unit, the knee angle measurement data from at least one of the first KAMD and the second KAMD and receiving the forefoot load measurement data from at least one of the first FLMD and the second FLMD. Upon receiving the knee angle measurement data and forefoot load measurement data the method performs following steps of determining, a knee angle variation of at least one of the left knee of the subject and right knee of the subject based on the knee angle measurement data received from at least one of the first KAMD and the second KAMD. The method also comprises determining a forefoot strain variation of at least one of the left forefoot of the subject and the right forefoot of the subject based on the forefoot load measurement data received from at least one of the first FLMD and the second FLMD. Thereafter, the method comprises evaluating a plurality of irregularities in a gait cycle of the subject based on deviations in the knee angle variation of at least one of the left knee and right knee of the subject and the forefoot strain variation of at least one of the left forefoot and right forefoot of the subject.
Further, the present disclosure discloses to a gait analysis system for facilitating gait analysis of a subject. The system comprises at least one of a first Knee Angle Measurement Device (KAMD) and a second KAMD. The first Knee Angle Measurement Device (KAMD) and a second KAMD is attached to a left knee and a right knee of the subject respectively for collecting knee angle measurement data using a fibre bragg grating sensor. The fibre bragg grating sensor is configured in the first KAMD and in the second KAMD. The system also includes at least one first Forefoot Load Measurement Device (FLMD) and a second FLMD. The first FLMD and a second FLMD is attached to a left forefoot and a right forefoot of the subject respectively for collecting forefoot load measurement data using a fibre bragg grating sensor. The fibre bragg grating sensor is configured in the first FLMD and in the second FLMD. Further, the system includes a gait analysis unit associated with at least one of the first KAMD, and the second KAMD, and with at least one of the first FLMD and the second FLMD. The gait analysis unit initially receives the knee angle measurement data of at least one of the left knee and the right knee of the subject from at least one of the first KAMD and the second KAMD respectively. The gait analysis unit also receives a forefoot load measurement data of at least one of the left foot and the right foot of the subject from at least one of the first FLMD and the second FLMD respectively. Based on the received knee angle measurement data and the forefoot load measurement data, the gait analysis unit determines a knee angle variation of at least one of the left knee of the subject and the right knee of the subject based on the knee angle measurement data and also determines forefoot strain variations of at least one of the left forefoot of the subject and right forefoot of the subject based on the forefoot load measurement data. Further, the gait analysis unit evaluates irregularities in the gait cycle of the subject based on the deviations in the knee angle variation of at least one of the left knee and right knee of the subject and the forefoot strain variation of atleast one of the left forefoot and right forefoot of the subject.
Furthermore, the present disclosure discloses a knee angle measurement device (KAMD) for measuring knee angle of a subject. The KAMD comprises a base perspex disc with a first movable arm. One end of the first movable arm is riveted to edge of the base perspex disc, and other end of the movable arm is attached to a thigh of the subject. The device also includes a rotating circular disc which is riveted concentrically over the base perspex disc. The rotating circular disc is pivoted with a second movable arm. One end of the second movable arm is riveted to the edge of the rotating circular disc and other end of the second movable arm is attached to a shin of the subject. Further, the device includes a cantilever beam with one end of the cantilever beam is attached to a raised platform from the base perspex disc and other end of the cantilever beam is connected to the rotating circular disc through a connecting mechanism. During the rotation of the circular disc, the rotating circular disc exerts a strain on the connecting mechanism which creates a strain on the cantilever beam. Further, the device also includes a fibre bragg grating (FBG) sensor with a photosensitive optical fibre bonded over the cantilever beam to acquire strain variation on the cantilever beam. In some embodiments, the device may include a FBG interrogator which is connected to the FBG sensor to determine the strain variation on the FBG sensor by transmitting a light beam of broad wavelength through optical fibre of the FBG sensor and by recording a shift in Braggs wavelength from the reflected light due to the strain variation on the optical fibre of the FBG sensor.
Furthermore, the present disclosure discloses a forefoot load measurement device to measure load on forefoot of a subject. The forefoot load measurement device comprises a foot wear sole with a plurality of layers. The plurality of layers comprises a top layer, a middle layer and a bottom layer, wherein the middle layer of the foot wear sole comprises an open slot in the fore foot area. A cantilever beam placed on the open slot in the forefoot area of the middle layer. One end of the cantilever beam is fixed to the middle layer and other end is connected to the top layer using a probe, wherein any strain on the top layer of the footwear sole is exerted on the cantilever beam. The device includes a fibre bragg grating (FBG) sensor with a photosensitive optical fibre bonded to the cantilever beam to acquire strain variations on the cantilever beam. In some embodiments a FBG interrogator is connected to the FBG sensor to determine the strain variations on the FBG sensor by transmitting a light beam of broad wavelength through the photosensitive optical fibre of the FBG sensor and by recording a shift in Braggs wavelength from the reflected light due to the strain variations on the photosensitive optical fibre of the FBG sensor.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of device or system and/or methods in accordance with embodiments of the present subject matter are now described, by way of example only, and with reference to the accompanying figures, in which:

Figure 1 illustrates an exemplary architecture of a system to facilitate gait analysis of a subject, in accordance with some embodiments of the present disclosure;

Figure 2 illustrates an exemplary architecture of knee angle measurement device in accordance with some embodiments of the present disclosure;

Figure 3 illustrates an exemplary architecture of forefoot load measurement device in accordance with some embodiments of the present disclosure;

Figure 4 shows a flowchart illustrating a method for facilitating gait analysis of a subject in accordance with some embodiments of the present disclosure;

Figure 5 illustrates schematics showing flexion and extension of the knee of the subject, in accordance with some embodiments of the present disclosure;

Figure 6 illustrates a subject wearing FLMD along with KAMD device mounted on the subject’s knee, in accordance with some embodiments of the present disclosure;

Figure 7 shows a graph illustrating simultaneous response of KAMDs and FLMDs while the subject is in locomotion in accordance with some embodiments of the present disclosure;

Figure 8a shows a graph indicating swing and stance phases time interval based on data obtained from KAMD in accordance with some embodiments of the present disclosure; and

Figure 8b shows a graph indicating swing and stance phases time interval based on data obtained from FLMD in accordance with some embodiments of the present disclosure.

It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and executed by a computer or processor, whether such computer or processor is explicitly shown.

DETAILED DESCRIPTION
In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a device or system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the device or system or apparatus.
Embodiments of the present disclosure relate to a method and system for facilitating gait analysis of a subject. The gait analysis system comprises a gait analysis unit, a knee angle measurement device (KAMD) and a forefoot load measurement device (FLMD). The KAMD is attached to knee of the subject. The knee angle measurement device measures angle between thigh and shin of the subject during a gait cycle of the subject. The knee angle measurement device employs a fibre bragg grating sensor for measuring the knee angle. The forefoot load measurement device is attached to a forefoot of the subject. The forefoot load measurement device measures load on the forefoot of the subject during the same gait cycle. The forefoot load measurement device employs a fibre bragg grating sensor for measuring load on the forefoot of the subject. The gait analysis unit receives the knee angle measurement from the knee angle measurement device and the forefoot load measurement from the forefoot load measurement device and estimates irregularities in the gait cycle of the subject. Since in the present disclosure the measurement data is obtained both from the KAMD and the FLMD simultaneously during same gait cycle of the subject using a single data acquisition system, the time synchronization complexity is eliminated.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
Figure 1 illustrates an exemplary architecture of a system to facilitate gait analysis of a subject, in accordance with some embodiments of the present disclosure.

As illustrated in Figure 1, the gait analysis system 100 comprises a Knee Angle Measurement Device 102 (hereinafter referred to as KAMD), Forefoot Load Measurement Device 104 (hereinafter referred to as FLMD) and a gait analysis unit 106 connected via a communication interface 108 to the KAMD 102 and the FLMD 104. The KAMD 102 is attached to knee of the subject. In an embodiment, the gait analysis system 100 may comprise at least one of a first KAMD 102-A and a second KAMD 102-B wherein the first KAMD 102-A is attached to the left knee of the subject and a second KAMD 102-B is attached to the right knee of the subject. The KAMD 102 measures knee angle between thigh and shin of the subject. In an embodiment, the subject may be a human. The KAMD 102 comprises a Fibre Bragg Grating (hereinafter referred to as FBG) sensor 102-1 to measure knee angle of the subject during a gait cycle of the subject. The FLMD 104 is attached to forefoot of the subject. The FLMD 104 is used to measure load on the forefoot of the subject during the same gait cycle of the subject. In one embodiment, the gait analysis system 100 may comprise at least one of first FLMD 104-A and a second FLMD 104-B wherein the first FLMD 104-A is attached to the left forefoot of the subject and the second FLMD 104-B is attached to the right forefoot of the subject. The FLMD 104 comprises a Fibre Bragg Grating sensor 104-1 to measure the load on the forefoot of the subject. The gait analysis unit 106 may include a processor 110 and a memory 112 coupled with the processor 110. The gait analysis unit 106 may include one or more modules 114 for analysing gait of the subject. In an embodiment, the one or more modules 114 may include a knee angle measurement module 116, a load measurement module 118 and a gait analysis module 120 as depicted in Figure 1.

The knee angle measurement module 116 in the gait analysis unit 106 may be configured to receive knee angle measurement data from at least one of the KAMDs 102-A and KAMD 102-B in the form of strain variations. Further the load measurement module 118 in the gait analysis unit 106 may be configured to receive the load on the forefoot of the subject in the form of strain variations 104 from at least one of the FLMD 104-A and the FLMD 104-B. The gait analysis module 120 may receive the knee angle measurement data from the knee angle measurement module 116 and determines a stance phase and swing phase in the gait cycle of the subject. The swing phase corresponds to the Gaussian shape of the knee angle variation obtained whereas the stance phase corresponds to the knee angle variation in almost zero. Further, the gait analysis module 120 may determine the duration of stance phase and swing phase, and the angular velocity achieved by the knee joint during the gait cycle. Similarly, the gait analysis module 120 may receive the forefoot load measurement data from the load measurement module 118 and determine the swing and the stance phase based on the forefoot load measurement data. The swing phase of the gait cycle corresponds to the zero-load baseline state as there is no load applied over the foot and the stance phase of the gait cycle corresponds to the state where load is acting over the FLMD 104. The gait analysis module 120 may also evaluate the duration of stance phase and swing phase from the forefoot load measurement data. In some embodiments, the gait analysis module 120, may identify the irregularities in the gait cycle of at least one of the left knee and the right knee based on the knee angle variation and the forefoot strain variations in the left knee and the right knee of the subject.

The architecture of KAMD 102 as illustrated in Figure 2, may include two circular perspex discs i.e. a base perspex disc 202 and a rotating circular disc 214. As an example, the base perspex disc 202 has a diameter of 8 cm and a thickness of 1 cm. As an example, the rotating circular disc 214 has a diameter of 4 cm and thickness 1 cm. The rotating circular disc 214 is riveted concentrically over the base perspex disc 202 such that the rotating circular disc 214 freely moves over the base perspex disc 202. The base perspex disc 202 further comprises a first movable arm 212 with one end of the first movable arm 212 is riveted to edge of the base perspex disc 202. In some embodiments, free end of the first movable arm 212 is attached to the thigh of the subject using as an example a velcro. In some embodiments, the base perpex disc 202 comprises a rectangular raised portion on the surface of the base perpex disc 202. The rotating circular disc 214 further comprises a second movable arm 204 riveted to edge of the rotating circular disc 214. In some embodiments the second movable arm 204 is attached to shin of the subject. The KAMD 102 further comprises a cantilever beam 206 with one end of the cantilever beam 206 attached to the rectangular raised portion on the base perspex disc 202 and the other end of the cantilever beam 206 is connected to the rotating circular disc 214 through a connecting mechanism 216. The connecting mechanism 216 may be a thread. The cantilever beam 206 may be made of stainless steel. In some embodiments, the rotating circular disc 214 may contain a pin 208 for receiving the connecting mechanism 216. In some embodiments, the rotation of the rotating circular disc 214 creates a strain on the connecting mechanism 216. As the rotating circular disc 214 is connected to the cantilever beam 206 through the connecting mechanism 216, the strain exerted on the connecting mechanism 216 is equally transmitted to the cantilever beam 206.

The KAMD 102 further comprises a Fibre Bragg Grating (hereinafter referred to as FBG) sensor 102-1 for measuring the strain on the cantilever beam 206. The FBG sensor 102-1 is bonded over the cantilever beam 206 to acquire strain variation on the cantilever beam 206. The FBG sensor 102-1 comprises a photosensitive optical fibre 210 to detect the strain on the cantilever beam 206. In some embodiments, the photosensitive optical fibre 210 of the FBG sensor 102-1 is connected to a FBG interrogator 211 for determining the strain variations on the FBG sensor 102-1. The FBG interrogator 211 may transmit a beam of light with broad wavelength through optical fibre 210 of the FBG sensor 102-1 and may records a shift in Braggs wavelength from the reflected light due to the strain variation on the optical fibre 210 of the FBG sensor 102-1.

In an embodiment, the KAMD 102 may be attached on the knee joint of the subject with the first movable arm 212 of the base perspex disc 202 tied to the thigh of the subject and the second movable arm 204 tied to the shin of the subject. In operation, during the gait cycle, the angular movement by the shin with respect to the thigh turns the rotating circular disc 214 by the same angle and, the angular movement of the rotating circular disc 214 initiates a pull on the cantilever 206 via the connecting mechanism 216, which in turn creates the strain on the cantilever beam 206 that can be acquired by the FBG sensor 102-1. In some embodiments, the degree of angular motion induced by the knee is directly scaled into magnitude of variation in strain obtained over the cantilever 206.

In some embodiments the KAMD 102 is operated as a tunable sensitivity device. The KAMD 102 is tuned to operate in low sensitivity mode, medium sensitivity mode and high sensitivity mode according to the requirement of measurement of the knee angle. The order of sensitivity of the measurement increases from the low sensitivity mode, medium sensitivity mode and high sensitivity mode. The KAMD 102 is tuned to operate in different modes by adjusting the pin 208 on the rotating circular disc 214. The adjustment of the pin 208 tighten the connecting mechanism 216 thereby creating more strain on the cantilever beam 206 for a small angular movement on the rotating circular disc 214.

The architecture of FLMD 104 as illustrated in Figure 3 comprises a footwear sole 302 with three layers and the FBG sensor 104-1. The middle layer of the footwear sole 302 may comprise an open slot in the forefoot area. A cantilever beam 304 is mounted so that the fixed end resides over the middle sole layer and the other end is affixed to the top sole layer through a probe 306 as shown in Figure 3. Any strain exerted on the top sole layer is equally transmitted to the cantilever beam 304 in the middle layer. In some embodiments, a slot is provided in the bottom sole layer in order to facilitate free movement of the cantilever beam 304. The FLMD 104 comprises an FBG sensor 104-1 with a photosensitive optical fibre 308, bonded over the cantilever beam 304 to acquire strain variations. In one embodiment, the FLMD 104 may be connected to a FBG interrogator 310. The FBG interrogator 310 may transmit a light beam of broad wavelength through photosensitive optical fibre 308 of the FBG sensor 104-1 and may record a shift in Braggs wavelength from the reflected light due to the strain variation on the photosensitive optical fibre 308 of the FBG sensor 104-1. The top layer and the bottom layer may act a protective casing to protect the FBG sensor and the cantilever beam 304 present in the fore foot area of the middle layer.

In operation, during the gait cycle, application of load over the forefoot area i.e. foot load 312 of the footwear sole 302 results in inward sag of the top sole layer. The movement of the top sole layer causes strain variations over the cantilever beam 304 through the probe 306, and the strain variations are acquired by the FBG sensor 104-1. In one embodiment, the cantilever beam 304 and FBG sensor 104-1 assembly acts as a displacement sensor which acquires the downward sag of the top sole layer. Also, the magnitude of foot load 312 applied on the forefoot area of the subject can be dynamically acquired by the magnitude of strain variations over the cantilever 304.

Figure 4 illustrates a flowchart illustrating a method 400 of facilitating gait analysis of a subject in accordance with some embodiments of the present disclosure.

At block 402, the KAMD 102 obtains the knee angle of the subject. In an embodiment, the KAMD 102 is worn by the subject on either or two of the knees of the subject i.e. on the left knee and on the right knee of the subject. The first KAMD 102-A is attached to the left knee of the subject and a second KAMD 102-B is attached to the right knee of the subject for obtaining knee angle measurement data for the left knee and the right knee of the subject. In one example, the subject may perform the knee flexion and extension as illustrated in Figure 5, wherein the knee flexion and extension are initiated by the knee joint by the rotational movement of the shin with respect to thigh as in Figure 5 and the flexion and extension creates the strain variation on the cantilever beam 206 of the KAMD 102. For example, the angular movement by the shin with respect to the thigh turns the rotating circular disc 214 of KAMD 102 by the same angle, initiating a pull on the cantilever beam 206 through connecting mechanism 216. Upon initiating a pull on the cantilever beam 206, the strain variations are created on the cantilever beam 206 and the FBG sensor 102-1 bonded over the cantilever beam 206 acquires the strain variations Thus, the strain variation obtained for either or both the left knee and the right knee are recorded by the KAMDs 102-A and 102-B attached to the left and right knee of the subject respectively.

At block 404, the gait analysis unit 106 determines the knee angle variation for the strain variations obtained from at least one of the KAMD 102-A and KAMD 102-B. In one embodiment, the gait analysis unit 106 transforms the strain variations received from the KAMD 102 into the knee angle measurement data. In some embodiments, the gait analysis unit 106 may determine the knee angle measurement data for the left knee and the right knee separately.

At block 406, the load on the forefoot is obtained by the FLMD 104. In one embodiment, the FLMD 104 is attached to at least one of the left forefoot and the right forefoot of the subject to receive the load on the forefoot of the subject. As an example, a first FLMD 104-A is attached to the left forefoot of the subject and a second FLMD 104-B is attached to the left forefoot of the subject. The subject is instructed to wear the FLMD 104 in at least one of the left forefoot and in the right forefoot which is in the form of footwear. For example, the application of load over the forefoot area of the FLMD 104 results in inward sag of the top sole layer of the footwear. In one embodiment, the inward sag of the top sole layer of the footwear pushes the cantilever beam 304 downwards via the probe 306, creating the strain variations over the cantilever beam 304. The FBG sensor 104-1 bonded on the cantilever acquires the strain variations.

At block 408, the gait analysis unit 106 determines the load on the forefoot of the subject based on the strain variations from at least one of the FLMD 104. In some embodiments, the gait analysis unit 106 receives the strain variations and transforms the strain variations into forefoot load measurement data. In some embodiments, the gait analysis unit 106 determines the forefoot load measurement data for at least one of the left knee and the right knee separately.

In some embodiments, the KAMD 102 is worn on knee of subject and the FLMD 104 is mounted on the foot of the subject as shown in Figure 6 to simultaneously acquire the knee angle from KAMD 102 and the load on the forefoot from the FLMD 104. The data thus acquired is analysed to evaluate the gait of the subject.

At block 410, the gait analysis unit 106 evaluates the irregularities in the gait cycle of the subject. The gait analysis module 120 evaluates the irregularities in the gait cycle based on the data acquired from KAMD 102-A, KAMD 102B, and FLMD 104-A and FLMD 104-B. The gait analysis module 120 may receive the knee angle measurement data for at least one of the left knee and the right knee and determines the stance phase and swing phase for at least one of the left knee and the right knee separately. Further, the gait analysis module 120 may determine the duration of stance phase and swing phase for at least one of the left knee and the right knee separately, the angular velocity achieved by at least one of left knee and the right knee during the gait cycle. The gait analysis module 120 compares the stance phase, swing phase, duration of stance phase and swing phase, and the angular velocity of the left knee and the right knee. Based on the comparison, the gait analysis module 120 evaluates the irregularities in the gait cycle of at least one of the left knee and the right knee of the subject.

Similarly, in some embodiments, the gait analysis module 120 may receive the forefoot load measurement data for at least one of the left forefoot and the right forefoot of the subject. The gait analysis module 120 receives the forefoot load measurement data and determines the swing and the stance phase based on the forefoot load measurement data received from either the left forefoot and from the right foot. The gait analysis module 120 also evaluates the duration of stance phase and swing phase based on the forefoot load measurement data. In some embodiments, the gait analysis module 120, identifies the irregularities in the gait cycle of at least one of the left knee and the right knee based on the knee angle variation and the forefoot strain variations of at least one of the left foot and the right foot.

As an example, subject is requested to wear FLMDs 104 on both the foot and two KAMDs 102 are mounted on the left and the right knees of the subject. The subject is then made to walk some distance and the data from all the four sensors in the form of knee angle and forefoot load on both the legs are acquired simultaneously. The simultaneous response of KAMDs 102 and FLMDs 104 while performing the walking exercise is illustrated in Figure 7. From the graph shown in Figure 7, it is observed that the subject initially begins to walk from a standstill position or stance which may be considered as the baseline zero degree knee angle. The motion of walking is initiated by the movement of one foot. Hence the FLMD 104 load decreases on the right foot which is physically happening by the angular motion provided by the knee joint on the right leg. Therefore, the knee angle variation curves begin from the right leg with the swing phase. Further, the right foot will be placed on the ground (i.e. the right leg will be in stance phase and left leg will be in swing phase). This cycle repeats as depicted in the normal walking phase. The trial is terminated at the walk ending phase, where both the legs are at stance phase which in turn results in both knee angles returning to zero as seen from the KAMD 102 response.

Furthermore for the gait analysis of the subject, a section of the normal walking phase is considered, wherein the knee angular motion from both the KAMDs 102 and forefoot load from both the FLMDs 104 are analysed separately, as shown in Figure 8a, and Figure 8b respectively.

The selected section in the normal walking phase comprises of two walking cycles. The knee angle variation from the right and left knee are found to be complementary to each other as seen in Figure 8a. It is also observed that the maximum knee angle achieved in the considered section (which is also termed as the range of angular motion during walking) is found to be 620 and 570 on right and left knee respectively. The duration of stance phase and swing phase on the right leg is found to be 0.824s and 0.702s respectively, which further evaluates as 54% stance phase in the walking cycle and 46% swing phase in the walking cycle. Similarly, the duration of stance phase and swing phase on the left leg is found to be 0.852s and 0.721s respectively, which further evaluates as 55% stance phase in the walking cycle and 45% swing phase in the walking cycle. The time duration and the fraction of contribution of swing phase and stance phase in the walking cycle on both left and right knee are found to be in good agreement with each other.

Similarly, the load data from both the foot in the selected section is found to be complementary to each other, as seen in Figure 8b. The peak forefoot load achieved on the right and left foot is 385N and 402N respectively. In the Figure 8b, the duration of time in which the right foot is in stance and swing phase is found to be 0.812s and 0.678s respectively, which further evaluates as 55% stance phase and 45% swing phase in the walking cycle. Similarly, the duration of time in which the left foot is in stance and swing phase is found to be 0.872s and 0.715s respectively, which further evaluates as 55% stance phase and 45% swing phase in the walking cycle. The time duration and the fraction of contribution of swing phase and stance phase in the walking cycle on both left and right foot are found to be in good agreement with each other.

The inherent advantages of the Fiber Bragg Grating sensor such as small footprint, passive sensor element, immunity to Electro Magnetic Interference and crosstalk, multiplexing capability and the like, enables the gait analysis system to be simple and provides an efficient way to analyse the gait of a subject. Also, in the present disclosure the knee angle and forefoot load data are acquired simultaneously during the same walking cycle using a single data acquisition system thus eliminating the time synchronization complexity.

The present disclosure obtains accurate data simultaneously from KAMD 102 and FLMD 104, and evaluates appropriate parameters that helps to identify the kinematics involved in gait of the human. The gait of the human thus analysed may be used to identify the neuro-muscular disorders. Thus, the present disclosure facilitates the gait analysis using the wearable devices KAMD 102 and FLMD 104 based on FBG sensor technology.

The terms "an embodiment", "embodiment", "embodiments", "the embodiment", "the embodiments", "one or more embodiments", "some embodiments", and "one embodiment" mean "one or more (but not all) embodiments of the invention(s)" unless expressly specified otherwise.

The terms "including", "comprising", “having” and variations thereof mean "including but not limited to", unless expressly specified otherwise. The enumerated listing of items does not imply that any or all the items are mutually exclusive, unless expressly specified otherwise.

The terms "a", "an" and "the" mean "one or more", unless expressly specified otherwise.

A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention.

When a single device or article is described herein, it will be clear that more than one device/article (whether they cooperate) may be used in place of a single device/article. Similarly, where more than one device or article is described herein (whether they cooperate), it will be clear that a single device/article may be used in place of the more than one device or article or a different number of devices/articles may be used instead of the shown number of devices or programs. The functionality and/or the features of a device may be alternatively embodied by one or more other devices which are not explicitly described as having such functionality/features. Thus, other embodiments of the invention need not include the device itself.

Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the embodiments of the present invention are intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Referral Numerals:

Reference Number Description
100 Gait Analysis System
102, 102-A, 102-B Knee Angle Measurement Device
102-1, 102-2. 104-1,104-2 Fibre Bragg Grating Sensor
104, 104-A, 104-B Forefoot Load Measurement Device
106 Gait Analysis Unit
108 Communication interface
110 Processor
112 Memory
114 Modules
116 Knee angle measurement module
118 Load measurement module
120 Gait analysis module
202 Base perspex disc
204 Second movable arm
206,304 Cantilever beam
208 Pin
210, 308 Photosensitive optical fibre
211, 310 FBG interrogator
212 First movable arm
214 Rotating circular disc
216 Connecting mechanism
302 Footwear sole
306 Probe
312 Foot load
,CLAIMS:We Claim:

1. A method for facilitating gait analysis of a subject, wherein the method comprises:
obtaining a knee angle measurement data of at least one of a left knee and a right knee of the subject using at least one of a first Knee Angle Measurement Device (KAMD) 102-A and a second knee angle measurement device (KAMD) 102-B respectively, wherein the first KAMD 102-A is attached to the left knee of the subject and the second KAMD 102-B is attached to the right knee of the subject;
obtaining a forefoot load measurement data of at least one of a left forefoot and a right forefoot of the subject using at least one of first forefoot load measurement device 104-A (FLMD) and a second FLMD 104-B, wherein the first FLMD 104-A is attached to the left forefoot of the subject and the second FLMD 104-B is attached to the right forefoot of the subject;
receiving, by a gait analysis unit 106, the knee angle measurement data from at least one of the first KAMD 102-A and the second KAMD 102-B;
receiving, by the gait analysis unit 106, the forefoot load measurement data from at least one of the first FLMD 104-A and the second FLMD 104-B;
determining, by the gait analysis unit 106, a knee angle variation of at least one of the left knee of the subject and right knee of the subject based on the knee angle measurement data received from at least one of the first KAMD 102-A and the second KAMD 102-B;
determining, by the gait analysis unit 106, a forefoot strain variation of at least one of the left forefoot of the subject and the right forefoot of the subject based on the forefoot load measurement data received from at least one of the first FLMD 104-A and the second FLMD 104-B; and
evaluating, by the gait analysis unit 106, a plurality of irregularities in a gait cycle of the subject based on deviations in the knee angle variation of at least one of the left knee and right knee of the subject and the forefoot strain variation of at least one of the left forefoot and right forefoot of the subject.

2. The method as claimed in claim 1, wherein the knee angle measurement data is obtained by measuring an angle between thigh and shin of the subject and the forefoot load measurement data is obtained by measuring load on the forefoot of the subject.

3. The method as claimed in claim 1 further comprises determining stance phase and swing phase in the gait cycle of the subject, time duration of the stance phase and the swing phase and an angular velocity achieved by at least one of the left knee and the right knee during the gait cycle.

4. A gait analysis system 100 for facilitating gait analysis of a subject, wherein the gait analysis system 100 comprises:
at least one of a first Knee Angle Measurement Device (KAMD) 102-A and a second KAMD 102-B, wherein the first KAMD 102-A is attached to a left knee and the second KAMD 102-B is attached to a right knee of the subject for collecting knee angle measurement data using a fibre bragg grating sensor (102-1, 102-2) configured in the first KAMD 102-A and the second KAMD 102-B respectively;
at least one of a first Forefoot Load Measurement Device (FLMD) 104-A and a second FLMD 104-B, wherein the first FLMD 104-A is attached to a left forefoot and the second FLMD 104-B is attached to a right forefoot of the subject for collecting forefoot load measurement data using a fibre bragg grating sensor (104-1, 104-2) configured in the first FLMD 104-A and the second FLMD 104-B respectively;
a gait analysis unit 106 associated with at least one of the first KAMD 102-A and the second KAMD 102-B, and with at least one of the first FLMD 104-A and the second FLMD 104-B, wherein the gait analysing unit 106 is configured to:
receive the knee angle measurement data of at least one of the left knee and the right knee of the subject from at least one of the first KAMD 102-A and the second KAMD 102-B respectively;
receive a forefoot load measurement data of at least one of the left foot and the right foot of the subject from at least one of the first FLMD 104-A and the second FLMD 104-B respectively;
determine a knee angle variation of at least of one the left knee of the subject and the right knee of the subject based on the knee angle measurement data;
determine forefoot strain variations of at least one of the left forefoot of the subject and right forefoot of the subject based on the forefoot load measurement data; and
evaluate irregularities in the gait cycle of the subject based on the deviations in the knee angle variation of at least one of the left knee and right knee of the subject and the forefoot strain variation of at least one of the left forefoot and right forefoot of the subject.

5. A knee angle measurement device (KAMD) 102 for measuring knee angle of a subject, wherein the knee angle measurement device (KAMD) 102 comprises:
a base perspex disc 202 with a first movable arm 212 wherein one end of the first movable arm 212 is riveted to edge of the base perspex disc 202, and other end of the movable arm 212 is attached to a thigh of the subject;
a rotating circular disc 214 is riveted concentrically over the base perspex disc 202, wherein the rotating circular disc 214 is pivoted with a second movable arm 204 wherein one end of the second movable arm 204 is riveted to the edge of the rotating circular disc 214 and other end of the second movable arm 204 is attached to a shin of the subject;
a cantilever beam 206, wherein one end of the cantilever beam 206 is attached to a raised platform from the base perspex disc 202 and other end of the cantilever beam 206 is connected to the rotating circular disc 214 through a connecting mechanism 216, wherein movement of the rotating circular disc 214 exerts a strain on the connecting mechanism 216 which creates a strain on the cantilever beam 206;
a fibre bragg grating (FBG) sensor 102-1 with a photosensitive optical fibre 210 is bonded over the cantilever beam 206 to acquire strain variation on the cantilever beam 206; and
a FBG interrogator 211 is connected to the FBG sensor 102-1 to determine the strain variation on the FBG sensor 102-1 by transmitting a light beam of broad wavelength through optical fibre 210 of the FBG sensor 102-1 and by recording a shift in Braggs wavelength from the reflected light due to the strain variation on the optical fibre 210 of the FBG sensor 102-1.

6. The knee angle measurement device (KAMD) 102 as claimed in claim 5, wherein the rotating circular disc 214 comprises a pin 208 on the rotating circular disc 214 to receive the connecting mechanism 216 which connects the cantilever beam 206 and the rotating circular disc 214.

7. The knee angle measurement device (KAMD 102) as claimed in claim 6 wherein the connecting mechanism 216 is a thread.

8. The knee angle measurement device KAMD 102 as claimed in claim 5 is operated in a tuneable mode wherein the KAMD 102 when tuned operates in at least one of low sensitivity mode, medium sensitivity mode or high sensitivity mode.

9. The knee angle measurement device KAMD 102 as claimed in claim 8 is tuned to operate in at least one of low sensitivity mode, medium sensitivity mode or high sensitivity mode by adjusting the pin 208 on the rotating circular disc 214, wherein adjusting the pin 208 increases the magnitude of the strain variations in the FBG sensor 102-1.

10. A forefoot load measurement device 104 to measure load on forefoot of a subject, the forefoot load measurement device 104 comprises:
a foot wear sole 302 with a plurality of layers, wherein the plurality of layers comprises a top layer, a middle layer and a bottom layer; wherein the middle layer of the foot wear sole 302 comprises an open slot in the fore foot area;
a cantilever beam 304 placed on the open slot in the forefoot area of the middle layer, wherein one end of the cantilever beam 304 is fixed to the middle layer and other end is connected to the top layer using a probe 306, wherein any strain on the top layer of the footwear sole 302 is exerted on the cantilever beam 304;
a fibre bragg grating (FBG) sensor 104-1 with a photosensitive optical fibre 308 is bonded to the cantilever beam 304 to acquire strain variations on the cantilever beam 304; and
a FBG interrogator 310 is connected to the FBG sensor 104-1 to determine the strain variations on the FBG sensor 104-1 by transmitting a light beam of broad wavelength through the photosensitive optical fibre 308 of the FBG sensor 104-1 and by recording a shift in Braggs wavelength from the reflected light due to the strain variations on the photosensitive optical fibre 308 of the FBG sensor 104-1.

11. The forefoot load measurement device 104 as claimed in claim 10, wherein the top layer and the bottom layer of the footwear acts as a protecting case to protect the fibre bragg grating (FBG) sensor 104-1 and cantilever beam 304 from external damage.

Dated this 13th day of November, 2018

Swetha SN
Of K&S Partners
Agent for the Applicant
IN/PA-2123