Control of Robot Driven by Multiple Ultrasonic Motors Based on Robust Parameter Design

An ultrasonic motor (USM) is difficlt to be mathematically described because of its complex energy conversion and nonlinear parameters from increasing temperature and changing operating conditions. To achieve good performance of a three-joint robot directly driven by USM, according to the operating characteristics of USM, a new position-velocity feedback control strategy is proposed. In the control strategy, there are a total of 18 controller gains to be tuned. Through a series of ”Design of Experiments” by the robust parameter design, an optimal and robust set of proportional integral derivative (PID) controller gains is obtained. Results show that the control strategy can achieve the best performance of the robot and the robust parameter design is effective and convenient to USMs.