A Design of Two-Degree of Freedom Controller for Two-Mass Positioning System with Small Inatia Ratio

Abstract

This paper descrives a design method of two-degree of freedom controllers for a low stiffness positioning system with a reduction gear. The gear apparently reduces the load inatia. This results in the difficulty of estimating torsional torque by a disturbance observer. Therefore. it is difficult to use resonance raito control method for the positioning system. In the proposed system. a state feedback controller(I-PD controller) is designed based on the feedback control theory so that the torsional vibration is significantly restrained. To improve the tracking performance, an adaptive feedforward controller is introduced. The responses of the positioning system for trapezoidal desiredoutput signals are measured. Experimental results demonstrate the effectiveness of the proposed two-degree of freedom controller.