Modelling of robotic leg for hemiplegic patient using biped robot

Abstract

Patients with hemiparesis have difficulties maintaining their balance. These skills can be regained with the aid of external motors and using a microcontroller to control the actuation of the motors. A biped robot with servo motors attached at each joint is fabricated. A clay model of the paralytic leg is made and attached to the hip of the body and the other leg of the biped is modelled as a 3-DOF RRR robot. A CAD model of the prototype was considered for verifying the control strategies. The control strategies include COP (Centre of Pressure) balancing, CMP (Centre of Mass) balancing and stepping sequence (change of support) during the motion of the biped. The control system analysis is performed by analyzing the swing vibration of the leg and root locus plot for checking stability. The stability control is enhanced by taking feedback from gyroscope sensor. A graphical interface is made my using python for analyzing the values from gyroscope and accelerometer sensor. These values are plotted for analyzing the dynamic stability of the body. The joint velocities, acceleration and torque values are analyzed. The setup is simulated in v-rap software. After the analysis, the limiting joint angles were found. The servo motors are actuated to the limiting angles if the body becomes unstable, the biped robot is programmed in a way that it is always stable.