Study on the exponential path tracking control of robot manipulators via direct adaptive methods

Exponential path tracking control represents an important issue pertaining to the transient performance of robot control systems. In this paper, the so-called Exp-transformation is applied to obtain transformed robot dynamics models which are used to derive several adaptive control algorithms that achieve exponential path tracking. In contrast to the existing composite adaptive control method; where both the tracking error and the prediction error are used and persistent excitation (p.e.) is required, the proposed strategy requires only the tracking error. This makes the control structure simpler and easier to implement. The main contribution of this paper is the development of practical control strategies for which the p.e. requirement is completely removed (as opposed to relaxing it to semi-p.e. as was done in a recent work). The fundamental idea introduced for exponential stability analysis is conceptually simple and global results are obtained. © 1992.