On the stability of hybrid adaptive controllers for robotic manipulators

An outline is presented of efforts being made to improve the stability and control of robotic manipulators which operate in constrained environments such as in the metal removal processes of machined parts. To this end, an adaptive hybrid architecture incorporating position control and force control subsystems is adopted. The position and force control subsystems are continually adapted according to prescribed equations which aim to minimize the error signals between the feedforward and the feedback forces. The control law contains time-variant PID gains. Criteria and conditions of stability of the control system include the system´s compensation for dynamic cross-coupling between force- and position-control loops, model-reference criteria, and Lyapunov´s 2nd method