A Study of Deadbeat Terminal Control for High Speed Low Vibration Robots

The primary limitation to increasing the operating speeds of robots, and hence their productivity, is the vibrations induced by high accelerations. Since these vibrations are usually only important near the endpoint of the arm trajectory, this paper proposes the use of a separate controller for this part of the trajectory, specifically designed for vibration control. This makes use of the fact that in the neighborhood of the endpoint the system can be considered linear. To solve the modeling problems accurate for the current endpoint and load conditions, it is proposed that a robot operator conduct a test run during which data is automatically taken. It is later used off-line by the robot microprocessor to obtain the system model in the neighborhood of the endpoint, and the feedback control gains. A deadbeat control law is studied here because of its time optimality and because it has a feedback form. The research here establishes, both by simulation and by experimental testing, that the overall approach has considerable promise. However, some new development is needed in the control law design to realize its promise.