Nominal performance recovery by PID+Q controller and its application to antisway control of crane lifter with visual feedback

We have recently suggested the PID+Q controller that consists of a PID controller, a stable free-parameter, and an internal model of plants. In this brief paper, we point out that the free parameter can be designed to improve the robust stability and the robust performance of the control system, and present a nominal-performance recovery problem to design the free parameter with better robust performance. Moreover, we apply the PID+Q controller to the robust antisway control of crane lifter in order to compensate the time delay caused by the vision-based measurement. After modeling the lifter system with the visual sensor as a pendulum control system with a time delay, we design a robust PD+Q controller and a PID+Q controller using the MATLAB LMI Toolbox. Finally, we implement the designed controller on a table-size lifter kit with the visual sensor to demonstrate the proposed PD PD+Q controller.