A new antagonistic actuator for robot control

The need for advances in actuators for robotic applications has been recognized by the research and development community for some time [Research Needed to Advance the State of Knowledge in Robotics, NSF Workshop, Rhode Island University, April, 1980]. A key limitation with existing actuator technology is the inability of these actuators to provide precision control especially under rapidly changing loads. The new actuation system proposed in this paper is of hydraulic type and works in much the same way as the human muscle system in precision control of a skeletal joint. Modular actuators are controlled in concert and antagonistically to provide high disturbance accomodation and precision motion. The system description is nonlinear and requires a unique non-linear disturbance utilization control law. An array of sensors are used in this control. Results indicate a significantly higher control fidelity for the antagonistic actuator than with conventional hydraulic actuators.