Safe arm with MR-based passive compliant joints and visco-elastic covering for service robot applications

In this paper a safe arm with passive compliant joints and visco-elastic covering for human-friendly service robots is presented. The passive compliant joint (PCJ) is composed of a magneto-rheological (MR) damper and a rotary spring. The rotary spring gives the arm compliant property, but also it might be a source of vibration. Therefore the damper is introduced for damping effect and works as a rotary viscous damper by controlling the electric current according to the angular velocity of spring displacement. In an unexpected collision, the joints and cover passively operate and attenuate the applied collision force. The force attenuation property is being verified through collision experiments showing that the proposed passive arm overcomes limitations of an active compliant control approach.