Roll autopilot design using second order sliding mode

Abstract

Sliding mode control is a well established non-linear control technique which ensures a robust performance in presence of matched uncertainties and disturbances. The only shortcoming of this control strategy is that the control signal generated, which provides the robustness is highly discontinuous and may lead to chattering. Recent advances in higher order sliding mode control indicate that the use of second order sliding mode control ensures the basic advantages of sliding mode control, that of robustness while maintaining continuous and chatter-free control. The super twisting algorithm which is the most popular second order sliding mode control can provide for finite time convergence against the matched uncertainties only. Here, a methodology has been proposed so that this algorithm can be extended to cater for unmatched uncertainties, particularly those arising from uncertain system matrix A. The proposed scheme is then applied for roll control of missile.