Improved Lyapunov-based decentralized adaptive controller

Graduation date: 1991An improved robot manipulator decentralized non-linear adaptive\ud controller that performs well in the presence of disturbances with\ud unknown parameters and non-linearities is presented in this work.\ud The proposed decentralized adaptive structure is a modification of\ud the controller developed by Seraji [13-17] and is characterized by an\ud auxiliary signal that compensates for the unmodeled dynamics and\ud improves the tracking performance, by a feedforward component based on\ud the inverse system to ensure high performance over a wide range and by\ud a PD feedback component of constant gain to improve the speed of\ud response of the system. As a result, a very accurate and fast path\ud tracking is achieved despite the non-linearities.\ud The scheme requires only the measurement of angular speed and\ud displacement of each joint, and it does not require any knowledge about\ud the mathematical model of the manipulator. Due to its decentralized\ud structure, it can be implemented on parallel processors to speed up the\ud operation.\ud The main advantages of the proposed control scheme over similar\ud controllers are that the control activity is smoother, it is less\ud sensitive to sampling size and to the time period elapsed when the whole\ud trajectory is traversed, as verified by simulations of several test\ud conditions of-two of the joints of the PUMA 560 robot arm