Control system design for a prosthetic leg using series damping actuator

Bio-Mechatronics is the field that deals with passive and active prosthetic limb design. The passive conventional prosthesis carries constant mechanical properties so that the motion of joints motion is not similar to that of humans while the active type prosthesis more realistically represents human motion. The latter is however, more expensive than passive prosthesis and consumes more energy. Semi-active type prosthesis is less expensive but its results are very much similar to that of active type prosthesis and it is a better solution to control the human gait artificially. This research is based on the design of a prosthetic leg that can simulate a pattern similar to that of a normal person´s gait. The research is divided into two parts: calculation of kinematics and design of control system. The forward and inverse kinematics is computed to analyze the position, orientation and workspace for the leg. Series damping actuator is used to control the swing phase of the leg and P-Controller is designed to control the swing and joint force on knee. This paper shows that a semi active prosthetic limb can emulate a real limb and in order to control a prosthetic leg Series Damping Actuator (SDA) can be used as a means to adapt the pattern of normal human gait and the walking pattern can be controlled accordingly.