Design and research of rolling missile autopilot with pulse width modulation actuator

Pulse width modulation (PWM) actuator system has been widely used for rolling missile. The application of PWM in control system of rolling missile is studied. The relationship between the autopilot gain and the dynamic characteristics of missile, such as oscillation frequency and damping radio, is described, the characteristic of control coupling resulting from low frequency PWM is mainly analyzed, and the relation among coupling strength, spinning frequency and aerodynamic time constant is discussed. The spectral characteristics of disturbance caused by coupling are obtained by spectral analysis. After modulation, the spectra of guidance and control commands for actuator remain unchanged; however, a high-frequency interference is introduced, which is related to spinning frequency, modulation frequency, and oscillation frequency of missile. Finally, the design criteria for autopilot of the missile are proposed based on the above conclusions. The mathematical simulation and Hardware-in-the-loop simulation results show that the application of PWM in rolling missile is feasible, and the design based on the criteria can reduce the effects of control coupling, and also improve the guidance precision.