Design of robust autopilot‐output integral sliding mode controllers for guided missile systems with parameter perturbations

The guided missile system is considered as SISO plant with parameter perturbations. The structure of the missile system is not suitable for the use of classical linear controllers. On the other hand, the missile system should be capable of good performances, such as zero steady state error, less settling time etc. Standard VSC control laws fail to control the steady state error due to the structure of the system matrices. For this reason we have proposed two new robust output integral sliding mode controllers and design procedures. An integrator is included in the sliding function, which results in the reduction and removal of the output error. The total control consists of two parts: equivalent control which compensates the nominal regime of the missile system; and VSC which compensates the parameter perturbations (changes in Mach number, altitude and mass of the vehicle, etc.) of the missile system. We have derived new constructive sliding and stability conditions for both cases by using Lyapunov’s direct method. Computer simulations indicate that this approach yields a satisfactory control performance.