Improving Fail-Safe Components in Rehabilitation Robots

In our previous study, two components for reducing risks in rehabilitation robots were proposed. One was a reflex mechanism, which is similar to the biological reflex, and the other was a fail-safe force sensor. In this paper, we present our efforts to try to improve these two components. First, for improving the reliability, we propose a new structure for the reflex mechanism, which consists of two solenoids and two springs in an antagonistic set-up. Experimental results using a prototype prove both its effectiveness for reducing impact force and its reliability. Second, a fail-safe force sensor with PSDs is proposed, which has a simple structure and can discriminate force direction. A method for developing a fail-safe force/torque feedback system is also proposed.