2008 Volume 21 Issue 10 Pages 320-326
Various methods for improving the robustness of adaptive backstepping control systems have been proposed. One of such methods uses an adaptive law with the parameter projection algorithm which realizes a projection action by changing the integral kernel of the adaptive law to another function. It is known that a stable adaptive backstepping control system is achieved based on the overparameterization scheme or high gain non-linear damping scheme when the change type projection algorithm is used for parameter projection. However, in the former scheme, the adaptive controller may be complex for a high order and high relative degree plant. A peculiar problem to high gain feedback such as actuator saturation and difficulty of numeric realization may be caused in the latter scheme. This paper shows that the change type projection algorithm cannot be applied to the tuning functions scheme. On the basis of the fact, this paper proposes a new design method for tuning functions scheme with non-change type projection algorithm. Also, it is shown that the proposed method can solve the problems of the conventional method.