Quadratic Optimal Control of a Two Flexible-Link Robot Manipulator

This paper is addressed at the problem of controlling a two-flexible-link manipulator system. Manipulators with some flexible links are attractive if high speed motion is required in manufacturing operations because they avoid the severe control problems associated with the large inertia forces generated when the large mass, rigid links in conventional robot manipulators move at high speed. In fact, only two of the links within a typical six degrees of freedom revolute-geometry industrial robot cause significant inertia forces and so only these two links need to be flexible. The development of a two-flexible-link system controller is therefore very relevant to larger manipulators because it can be readily expanded by adding simple controllers for the other rigid links. Two-alternative controllers are developed in this paper, a computed-torque controller and a quadratic optimal controller. Simulations confirm the superior performance of the latter.