An apparatus was designed to rehabilitate human knee joint besdies evaluating the strength of the joint. The apparatus is a dynamometer which measure the knee joint torque for clinical purposes and include driven force system (servo motor), power transmission system (timing belt), control system (speed controller and sensors), instrumentation system (sensors, amplifier, filtering and interfacing) and safety system (microswitchs). The resistance torque induced by the servo motor is controlled by the speed driver based on the clinical protocol, i.e., isometric or isokinetic. In each algorithm of control, speed set point is calculated based on torque feedback proportional to the desired resistance. In the instrumentation system, position, velocity and torque of the knee joint is measured and displayed in a PC after proper signal conditioning. Monitoring and controlling was done by simulink environment of Matlab software using real time windows target toolbox.
