Decentralized sliding mode control for bank-to-turn missile with backstepping technique

A decentralized backstepping approach, combined with sliding mode control, is used to design BTT (bank-to-turn) missile autopilot. The proposed scheme converted the nonlinear mathematical model of BTT missile into three nonlinear interconnected subsystems based on the idea of decentralized control. Each subsystem is represented as the inner loop and the outer loop, such that sliding model controllers can be designed based on backstepping technique. The strong nonlinear couplings between three channels of BTT missile is assumed to be partially measurable and compensated in the controllers. Due to the couplings are difficult to be measured precisely, an adaptive law is derived to estimate the uncompensated coupling and external disturbances. The overall system is proved to be asymptotic stable by the Lyapunov stability theorem and all the signals are bounded. Numerical simulation is given to validate the effectiveness of the controller that the system outputs track the commands well and are robust to disturbances.