Computed torque vs quadratic optimal control for a two-flexible-link robot

With the increasing demand for faster robot movements in manufacturing operations, there is now a widespread interest in developing low-mass flexible-link robot manipulators which avoid the severe control problems caused by the large inertia forces generated when the large-mass, rigid links associated with conventional robot manipulators move at high speed. The necessary pre-requisite for a flexible manipulator controller is the existence of a suitable-accurate model of the manipulator system. The approach considered is to develop a single-link model and then expand this into a two-link model taking proper account of the coupling between the two links. As errors are cumulative due to the dynamic coupling between the links, it is essential that the basic single-link model on which the two-link model is built is of very high accuracy. Computed-torque and quadratic optimal controllers based on this model have been developed. This development together with performance simulations are presented.