A nonlinear sliding mode compound autopilot for aircrafts with reaction jets

A new approach to the compound autopilot design for aircrafts with blending actuators is presented. The method is based on nonlinear sliding mode control, and adopts synergistic control strategy dealing with two different actuators (dynamic fins and reaction jets). An observer is further designed to estimate and smooth the complex term whose analytical expression cannot be obtained. In addition, a chattering attenuation method is proposed to eliminate the chatter caused by SMC. The convergence domain of the system is also discussed. Then, the autopilot is tested on a aircraft model with uncertainties and disturbances, and compared with pure aerodynamic control. Simulation results show the capabilities of the synergistic control strategy and excellent performance of the compound system.