Characteristic models and adaptive iterative learning control of linear servo systems

This paper presents characteristic models of linear servo-systems and a characteristic-model based adaptive iterative learning control scheme. The system undertaken is shown to be a sixth order linear time invariant system, when utilizing the "i_d=0" control strategy. The characteristic models from first-order to third-order are obtained, where the characteristic parameters are both time-varying and iteration-dependent. The least squares iterative learning algorithm with a forgetting factor is introduced to estimate the unknowns, and a saturated adaptive iterative learning controller is given, based on the LQ optimal control method, to realize that the system\´s outputs completely follow the desired trajectory over the entire interval. Numerical results are presented to verify effectiveness of the proposed learning control scheme.