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

The exponential transformation is applied to obtain transformed robot dynamics. This is 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 (PE) is required, the proposed strategy requires only the tracking error. This makes the control structure much simpler and easier to implement. The main contribution of this work is the complete removal of the PE requirement as opposed to relaxing it to semi-PE. The fundamental idea introduced for exponential stability analysis is conceptually simple and global results are obtained.