Design of a rotary elastic actuator for use as torque-actuator in rehabilitation robots

In this paper, the modelling and control of an elastic actuator are investigated. First, the specifications of the actuator are defined and then a model of the actuator is presented reflecting the required specification. Further, the model is analysed and investigated to evaluate the specification of the system. Moreover, a control algorithm is proposed to be used for the actuator. The control algorithm utilizes a PI controller for the actuator speed, and a PID controller for the actuator output torque.. Integrating the controllers into the actuator, a series of tests are performed on the actuator to show the actuator performance. The first is the accuracy of the output torque delivered by the spring. The results of the first test indicate that the spring behaves linearity, and can be used simply to deliver linear torque. The second test is the frequency response bandwidth measurement. The results show that the actuator is capable of excreting torque in the frequency range of rehabilitation applications. Finally, it is shown that the actuator can provide the rehabilitation requirements properly.