A six degree-of-freedom wrist with pneumatic suspension

This paper presents a new six-degree-of-freedom pneumatic fine-motion device that can be used as a robot wrist, a teleoperation master, or in other fine-motion applications requiring high position resolution and force control. The device uses six pairs of externally pressurized mechanical bellows as a pneumatic suspension without actuator friction. Forces and torques are controlled by servoing differential pressure across each pair of bellows using novel high-flow flapper valves. Aspects of design and control are presented. Experimental results show that the valves employed have no hysteresis and have flow exceeding that of any single stage pneumatic valve currently available on the market, while the pneumatic-suspension device shows promise as a force-reflecting teleoperation master