Analysis, modeling, manufacturing and control of an elastic actuator for rehabilitation robots

In this paper, modelling and control of an elastic actuator for rehabilitation robots are investigated. First, the required performance of the actuator is determined, and then a model of the actuator is proposed. Further, a control algorithm is presented to meet the required performance specications. The control algorithm consists of an external PID torque controller and an internal PI speed Controller. Experimental tests are performed on the actuator to evaluate the actuator performance. First, an accuracy evaluation test is performed on the actuator to calibrate the torque measured by the spring. The results exhibit the springʹs linear characteristics and the capability of torque measurement. Second, the bandwidth of the actuator is measured through sinusoidal input. The results show that the actuator is capable of delivering the required torque in the frequency range of rehabilitation. Third, an impedance measurement test is performed on the actuator indicating that it is capable of exerting the lowest and/or highest resistance on patient movement if required. As a result, it is shown that the proposed actuator can satisfy the whole rehabilitation requirements appropriately.