Arm Rehabilitation Robot Impedance Control and Experimentation

This paper is devoted to design a robot control system for assisting in the rehabilitation of patients who suffer from debilitating illness such as stroke. The rehabilitation robot discussed in this subject is able to guide patient´s wrist to move along planned trajectory in both horizontal and vertical plane, and train the elbow joint as well as shoulder joint. Increasingly the robot requires interacting directly with human, so it needs to control not only the robot position but also the applied forces. In this paper, it presents a new position-based impedance control that involves a combined force feedback and position control. At the meantime, it gives a conversion relationship between the commands of force and position. A new controller structure is proposed, which consists of an outer force controller enhanced by impedance control. The target impedance model modifies a desired trajectory according to the force signals. The modified trajectory acts as a compensate resource adding to the desired trajectory. Then the robot tracks the trajectory using the inner position controller. The experiment results show that the trajectory tracking based on force feedback on the condition of realizing the target impedance is feasible, and it can achieve better training effect by chosen different impedance parameters in the light of patient´s illness.