Theoretical validation of pneumatically actuated below-hip orthosis for partially paralysed subjects

Abstract

The force and moment at ankle, hip and knee joints are determined based on reaction forces and moments acting at those joints. The reaction forces and moments developed at these joints are due to the ground reaction forces at the foot. These ground reaction forces are measured using force plates. And using newton's equations of motion, the forces and moments at ankle, knee and hip joints are calculated from the force plate data. In this work, reaction forces and moments acting at ankle, knee and hip for heel strike, mid stance and toe-off regions are calculated from force plate data, using Newton's equations of motion. In second section a mathematical relation is developed between exoskeleton knee moment and the knee angle. Thus by measuring the angles of knee, the controller can decide the amount of moment that has to be supplied to the exoskeleton's knee joint for its actuation. For validating the developed mathematical relationship, the knee moment calculated using mathematical relationship is compared with the knee moment calculated using newton's equations of motion. The comparison result curve obtained from both the methods shows a similarity in nature which validates the use of pneumatic actuator as a perfect fit for orthosis design.