A new approach to eliminating variable structure control chattering with application to flight vehicles

Because of its effectiveness in dealing with modeling uncertainties, variable structure control (VSC) has been widely used for robust control design. However, current VSC design method leads to chattering due to the discontinuous control action involved. How to eliminate the undesirable chattering in VSC has been an interesting yet challenging topic of research. Most existing methods for chattering elimination are achieved at the price of control precision. In this paper, a new approach is introduced to remove chattering without sacrificing control precise. The idea behind the proposed approach is extremely simple: instead of designing the control input directly, the control (compensating) rate is designed. Once the rate of the compensating unit is determined, the control input is readily obtained via integration. It is shown that such a treatment leads to bounded and smooth control action while at the same time maintains asymptotical system stability. Simulations on heading speed control of flight vehicle verify the effectiveness of the method.