Control of a Six-Degree-of-Freedom Industrial Manipulator Modeled with Seven Link and Joint Flexibility Components

A new controller design is proposed for manipulators modeled with joint and link compliances. First, a nonlinear feedforward and a PID state feedback components are employed in the controller, and manipulator dynamics is converted into error-driven system dynamic equations. Then, the error-driven dynamic equations are stabilised by using the second method of Lyapunov. Special structure of the Lyapunov matrix equation is exploited and an explicit solution to this equation is presented. Our analysis also shows that controller performance can be enhanced through the modulation of this solution. The proposed controller is numerically implemented on the model of a six-degree-of-freedom Cincinnati Milacron T3-776 industrial manipulator which is modeled with three joint and four link flexibilities. The simulations show satisfactory path tracking and oscillation rejection properties.