Resonant control of a flexible manipulator system

Abstract

A single link flexible manipulator system is a single-input multi-output system. It has a single input as motor torque; and hub angle and tip deflection as outputs. This system is one type of industrial robot which is associated with high vibration and tip deflection due to rigid-body motion and elastic motion during its operation. In this work an integral resonant control was designed using the resonant frequencies of the system to control the vibration and tip deflection. The resonant frequencies are obtained from an experiment using finite element method. These frequencies with their corresponding damping ratios are used to design the resonant controller in such a way to add damping to the system and cancel the effect of vibrations at these natural frequencies of the system. The aim of this work is for the hub angle to track a reference angle without vibration and to achieve low tip deflection. The resonant controller is used as the inner feedback loop to suppress the vibration effect. To achieve zero steady state error an integral control gain is added to the system at the outer feedback loop. Three others control schemes are designed and compared to investigate the control performance of the integral resonant control. These control schemes are fuzzy logic controller, proportional integral controller and pole placement controller. All these control schemes are designed to add damping to the hub to suppress vibration such that the hub angle tracked the reference angle to achieve precise hub angle positioning and regulates tip deflection to zero, with zero steady state error. MATLAB Simulation environment is used to implement the performance of each control scheme. Furthermore, to test the robustness of the integral resonant control as compare with others controllers, different payload values are used to investigate the control performance and compare the results.