Discrete-Time Model Reference Adaptive Controller Designs for Robotic Manipulators

On-line computer control with high speed and accuracy is needed in industrial robotics. Thus, discrete-time controller design for robotic manipulators is necessary. In this paper, the two continuous-time model reference adaptive control schemes presented in [1] are put forth in discrete forms. The stability analysis is stemmed from the Lyapunov´s Direct Method [2]. It guarantees the asymptotic stability of a system. The same as any discrete-time control systems, the time required for the computer to perform the necessary computation may result in extended sampling time, which could degrade the stability of the system. In this paper, we obtain the sufficient condition of stability for the designed discrete-time controllers. A set of right sampling time and weighting factors are chosen to show the highly accurate tracking. Through the MATLAB software [3] simulation, we can see that the manipulator does follow the desired trajectory with high accuracy even when the payload is changing. It proves the effectiveness of the designed controllers.