Neelesh Kumar

Estimation of Forces and Moments of Lower Limb Joints from Kinematics Data and Inertial Properties of the Body by Using Inverse Dynamics Technique

In this paper, the forces and its moments acting on hip, knee & ankle joints of the body have been estimated with the help of kinetic models for better biomechanics understanding of human gait. This helps in accurate measurement of segmental masses, acceleration, joint centers and moment of inertia acting at various joints. Free Body Diagram (FBD) and Link Segment Model (LSM) are used for computing forces & moments using Inverse Dynamics (ID) technique. Available lower limb walking model is limited in terms of number of joint forces and moments are analyzed; so, the improved biomechanical model for kinetic analysis of human walk involving lower limb joints & muscles is proposed which estimate the forces acting on the hip joint, knee joint & ankle joints. This was also performed to understand the cause of deviation in any movement by estimating the patterns of forces acting on lower limb joints. Result analysis provides input parameter for the development of prosthetic foot design. by informing the force and moment values of lower limb joints. This analysis will also help for quantification of lower limb prosthetics.

Exoskeleton Device for Rehabilitation of Stroke Patients Using SEMG during Isometric Contraction

Robots are becoming more interactive and assisting to human beings day by day. They are serving humanity in the fields of industry, defense and medicine. Exoskeletons are also devices that reside in category of wearable robotics. An exoskeleton is an external structural mechanism with joints and links corresponding to those of the human body. With applications in rehabilitation medicine and virtual reality simulation, exoskeletons offer benefits for both disabled and healthy populations. Exoskeletons can be used as a capability magnifier or assisting device. This paper presents a proposed design for smart active exoskeleton for lower limbs. This proposed exoskeleton design not only assist a person but also tries to improve its GAIT. The twin wearable legs are powered by Actuators, all controlled by a microprocessor. The simulation results of the control mechanism shows its smart capabilities. In addition, the processor based control produces a more natural muscle like activity and as such can be considered a soft and bio-mimetic actuation system. This capacity to “replicate” the function of natural muscle and inherent safety is extremely important when working in close proximity to humans. The integration of the components sections and testing of the performance will also be considered to show how the structure and actuators can be combined to produce the various systems needed for a highly flexible/low weight clinically viable rehabilitation exoskeleton.

Knowledge base generation and its implementation for control of above knee prosthetic device based on SEMG and knee flexion angle

Advanced intelligent knee prosthesis for trans-femoral amputees requires a versatile control strategy and associated control algorithm. Control strategy was evolved by mapping surface EMG (SEMG) from four muscles of healthy lower limb of a unilateral trans-femoral amputee and knee flexion angles (KFA) during various phases of a gait cycle. The SEMG and KFA are calibrated to three walking speeds modes i.e., slow, normal and fast. Sensor mechanisms feeds real-time data to controller to generate an appropriate control output signal based on available knowledgebase which calculates the patients gait parameters i.e., KFA and SEMG from associated muscles during the corresponding phase of walk. Important aspect of control strategy is the development of knowledgebase proves that the SEMG signal generates recognisable pattern for change in walking speed when signals were analysed in time and frequency domain. These patterns were quantified and utilised for controlling electro-pneumatic knee joint.

Investigations on postural stability and spatiotemporal parameters of human gait using developed wearable smart insole

Abstract Measurement of spatiotemporal parameters of human gait is important for designing new, intelligent and efficient prosthetic and orthotic devices. The paper presents a novel application of smart insole for measuring force generated at various pressure points during dynamic gait on a human foot. Besides recording and analysing the spatiotemporal parameters during stance phase, the developed sensor is also used for development of active orthotic devices. Data from the sensors is analysed in LabVIEW software for detection of plantar force and temporal gait parameters. The smart instrumentation allows processing, display and storage of gait parameters and gait events in real time. Variations of pressure pattern reported by gait experiments can also be used in identifying an accidental fall. This information will be used as a feedback signal for controlling the motion of an indigenously developed gait assistive device, i.e. an active orthotic device. Pressure at the heel and great toe points is higher than the metatarsal heads during dynamic walk. It is higher at the heel and metatarsals points than the toe point during standing position.

Computer aided diagnostic tool for osteoporosis estimation

Quantitative estimation of osteoporosis is the need of the hour. A majority of the older population worldwide is suffering from this disease. X-ray examinations are the most widely used method for osteoporosis estimation. It has severe limitation of examination being qualitative. The paper presents a novel approach by digitising the X-ray films using an X-ray digitiser and analysing the digitised films using LabVIEW Software. The method calculates the Osteoporosis Estimation Index on the basis of the ratio of histogram calculated for selected reference ROI and measurand ROI on the digitised patient images. The results indicate the accuracy and reliability of the technique over the present methods used.

Algorithm for Kinematic Measurements using Active Markers

Kinematic measurements using Active Markers are well known methods. This paper aims at the development of an image analysis algorithm and LabVIEW based software tool for active marker based gait analysis. Active markers in the form of light-emitting diodes (LEDs) were positioned at anatomical landmarks to measure the coordinated kinematics of human joints.

Allan variance the stability analysis algorithm for MEMS based inertial sensors stochastic error

MEMS based inertial sensors are widely used due to their small size, low cost, and low power requirements. Inertial sensors are graded as per the error exhibited by them, therefore for any application at hand the error model of these sensors is explicitly considered in the unit model. In this paper, post calibration residual and stochastic errors are modelled by time domain stability analysis standard, the Allan variance (AV). Cluster sampling based various variance techniques with improvement in estimation accuracy and confidence of interval are considered. The effective degree of freedom for overlapping AV, modified AV and total variance techniques are calculated with chi-square statistic. Temperature effect on AV is observed and stochastic error coefficients are extracted from experimental data for error model of inertial sensors. The reported results are within 1s confidence of interval of inertial sensors specifications datasheet provided by the manufacturer.

Inertia-based angle measurement unit for gait assistive device

The study and estimation of various joint angles in humans has important significance in medical treatment, rehabilitation, physical training and so forth. Exoskeleton devices that can enhance human’s performance or assist disabled people have been developed in recent years. This paper describes a developed measurement system to estimate various human joint angles during a human gait using a MEMS bases low-g three-axis accelerometer (ADXL 335). A LabVIEW-based measurement system is developed to calculate the tilt angles of the accelerometer, based on the physical model of three acceleration components of the same. With the developed algorithm based on tri-axis tilt sensing, an ADXL 335 IC is used for measuring roll and pitch components, which are of numerous use in rehabilitation robotics. A combination of three sensor assembly is used per leg to calculate various joint angles viz. hip, knee and ankle. NI cDAQ-9172 with NI 9205 I/O module is used for acquiring signal from the accelerometer and the algorit...

Component analysis of ground reaction force with respect to variable walking speeds

The measurements of components of ground reaction force (GRF) are important in biomechanical analysis for clinical gait assessment, gait research, rehabilitation, ergonomics and sports. Ground reaction forces (vertical, fore-aft, lateral) are the reaction forces as a result of contact between the foot and the ground and these forms an integral part of human movement analysis. The purpose of this study was to demonstrate the effects of walking speed on GRF using Kistler quartz force platform embedded on the floor. In order to minimise differences in the gait of normal subjects due to ‘constrained’ walking, subject were requested to walk with their self-selected walking speed on the walkway. Components of GRF were recorded and analysed using Kistler’s Bioware software. It was convincingly observed that with increasing walking speed magnitude of vertical component of ground reaction force increases at F z 1 and F z 3 whereas decreased at F z 2 . The for-aft component shows an increasing trend at F y 1 and F y 2 with increasing walking speed but no such trend can be seen in case of the lateral component.

Kinematic measurements of human motion using accelerometer and goniometer for development of prosthetic knee

The aim of this research was to develop and validate a sensing mechanism for accurate measurement of the acceleration of human body segments and knee joint angle for gait analysis. The experimental results are correlated to establish the relation between knee angle and acceleration of lower limb. The sensing mechanism consists of indigenously developed two tri-axis accelerometers and one commercially available electro-goniometer. Experimental trials were done for walking at different speed on electric treadmill to acquire knee flexion-extension angles and acceleration of normal subjects. These correlated findings will be helpful in development of a transfemoral prosthetic device, i.e., electronic knee.