Modeling and Control of Two Degree of Freedom Bionic Foot

Abstract

Many people are affected by conditions like stroke, spinal cord diseases, cerebral palsy, and nerve injuries, leading to impaired leg function. Bionic foot assist in maintaining stability and posture, offering vital aid to those with mobility issues for improved quality of life and rehabilitation. Consequently, the use of bionic foot has increased. Bionic foot comprising electrical and mechanical components, provide comfort and support for individuals with mobility problems. An encouraging solution is to introduce bionic foot robots to help patients having mobility problems during their recovery journey. Designed to mimic the human skeletal system, these robots offer valuable assistance in restoring the natural gait cycle of patients having mobility problems. The proposed approach introduces a bionic foot designed to support movement of human ankle joint, marking a significant advancement in rehabilitation technology. Although human ankle joint actually exhibits 3 DOF motion, we consider 2 DOF motion of human ankle joint i.e., plantarflexion and dorsiflexion and, inversion and eversion as they are dominant during normal motion of human body. We designed two systems to control the motion of human ankle joint. Firstly, we have used two actuators, one for each degree of freedom to control the motion of ankle joint. Secondly, we have used an actuator to control the plantarflexion and dorsiflexion motion and Spring-Damper system to control the inversion and eversion motion of the human ankle joint. For both systems, we derive the mathematical model and then we design the PD controller using MATLAB/Simulink. For plantarflexion and dorsiflexion motion, we give standard pattern of human ankle gait as input and for inversion and eversion motion, we provide pulsating signal as our input for both the systems. After implementation, the response of the human ankle motion was precise, accurate and smooth. The torque applied by the actuators was also in the acceptable range.