Some improvements on model free controller

Firstly we make a brief introduction of the algorithm and astringency of existing model free controller and then in this paper propose two methods to improve the existing controller. On the one hand, a model free controller with dead zone is presented in order to avoid frequent movement of control action and eliminate the vibration of the system in some conditions. On the other hand, the problem of model free controller with constraints is considered. This problem is reduced to a multi-objective programming (MOP) and a multilevel ordering method is used to accomplish the programming with respect to the sense of the control problem. The effectiveness of the improved controllers is verified via two numerical examples.