Motion Control of a Robot Manipulator in Free Space Based on Model Predictive Control

Abstract

This chapter presented a simplified approach to predictive control adapted to robot manipulators. Control schemes were derived for velocity control as well as position tracking, leading to general predictive equations that do not require online optimization. Several justified simplifications were made on the deterministic part of the typical predictive control in order to obtain a compromise between the accuracy of the model and the computation time. These simplifications can be seen as a means of combining the advantages of predictive control with the simplicity of implementation of a computed torque method and the fast computing time of a PID. Despite all these simplifications, experimental results on a 6-DOF cable-driven parallel manipulator demonstrated the effectiveness of the method in terms of performance. The method using the exact solution of the optimal control appears to alleviate two of the main drawbacks of predictive control for manipulators, namely: the complexity of the implementation and the computational burden.Further investigations should focus on the stability analysis using Lyapunov functions and also on the demonstration of the robustness of the proposed control law.