Design of a missile autopilot using adaptive nonlinear dynamic inversion

Traditional missile autopilot design typically uses a three loop feedback topology with gains dependent on the current flight condition of the missile. These gain values are obtained by interpolation on a predefined gain table. The gain values that make up this table are designed to balance performance and stability on the grid of flight conditions that define the missile's flight envelope. Robustness to parameter variation either requires a dense gain table, which necessitates a significant amount of on-board memory, or large stability margins, which may limit the aggressiveness of the missile's performance. This paper describes the continuing autopilot design project adaptive nonlinear dynamic inversion (ANDI). The ANDI autopilot uses nonlinear dynamic inversion with an adaptive element to account for errors in the inversion process. A reference model is designed to provide the desired output performance. This technique allows the missile's performance to be tuned by simply adjusting a few reference model parameters. This results in a design that is robust with respect to aerodynamic modeling inaccuracies and to external disturbances.