Spinning missile dynamic inversion controller robustness analysis using Lyapunov methods

A two time-scale separation based nonlinear dynamic inversion controller was designed for the spinning missile. A state-space formulation of the control system with the aerodynamic coefficient uncertainties was presented. The nonlinear controller robustness was analyzed using Lyapunov methods. Associating with the actuator's capability, the bound of inner loop time constant was obtained. The aerodynamic coefficient uncertainties boundary was calculated. The result demonstrates that the advisable range of inner loop time constant is large when the uncertainties vary to make the airframe static stable, vice versa. The controller becomes more sensitive against the uncertainties when the inner and outer loop time constant scale increases. Comparing with the three loop controller, the dynamic inversion controller is less robust, but more stable.