DESIGN OF A CONTROLLER TO REDUCE RESIDUAL VIBRATION IN THE POSITIONING CONTROL OF FLEXIBLE ROBOTIC MANIPULATORS

Residual vibration refers to the structural vibrations which continue after the completion of a movement by a robotic manipulator from one position to another. These low-frequency vibrations occur at the damped natural frequencies of the system and require a fixed amount of time at the end of the movement to allow these unwanted vibrations to settle.;The accuracy with which the peak frequency is determined is shown to have a significant effect on the ability of the controller to reduce residual vibration. The software algorithms together with the capabilities of appropriate test equipment enable the controller to determine the peak frequency with a high degree of accuracy. The controller also provides the flexibility for adapting to changing system parameters as well as variations in the manipulator payload.;The controller was tested by using it to control a simple shaker system, a one-axis rotational system, and a commercial robotic manipulator. These represent practical applications of the control approach. The test results indicate that the controller significantly reduces the residual vibration for various payloads and automatically accomplishes this goal under the control of the developed software algorithms.;The research effort documented in this dissertation is aimed at developing a control method which will reduce the residual vibration in a robotic manipulator while also reducing the time required to arrive at the desired final position. The application of this control method involves the design of a controller to (1) test the structural dynamic characteristics of the robotic structure and analyze these characteristics in order to determine the natural frequencies of the system at the endpoint, and (2) then design a control drive signal which reduces the input energy occurring at these natural frequencies. The controller is also capable of assessing the effectiveness of this calculated drive signal in reducing the residual vibration in the system.