STABILITY AND ROBUSTNESS PROPERTIES OF A SIMPLE ADAPTIVE CONTROLLER

A low-order adaptive tracking controller is proposed for linear time-i nvariant plants viith a relative degree not exceeding two. The order o f the plant is not required to be known a priori. The algorithm is rob ustly stable with respect to small linear time-invariant plant perturb ations and bounded disturbances. The robustness is achieved by using a projection of the parameter estimates in the control law. An addition al a priori information needed to design the controller is bounds on t he plant parameters, In the absence of plant perturbations and disturb ances, perfect tracking is obtained.