Mechatronic Design & Adaptive Control of a Lower Limb Prosthesis

Lower limb prostheses have undergone significant developments in the last decades. However, there are several areas that have a scope for improvement through simplifications in the mechatronic design as well as in the control architecture. This paper focuses on the mechatronic design of a powered transtibial prosthesis and on the implementation of a control architecture, which is based on an adaptive frequency oscillator method that makes use of one inertial measurement unit. The control is capable of providing a positive push-off power to the prosthesis during level-ground walking and of adapting the response of the prosthesis to different walking speeds. The control architecture has been implemented and validated on a 3D printed prototype of a transtibial prosthesis. The experimental results show that the ankle joint can mimic the angle of a healthy subject with a root mean square error of 2.9° and that the gait transitions are tracked within two gait cycles.