6. Nonlinear Control of Airplanes and Helicopters

Chapter 6 focuses on the predictive control of airplanes and the backstepping control of quadrotor helicopters. The airplane is an LPV system which is internally stabilized by disturbance observer and externally controlled by high level RHC. The control design is illustrated for the pitch rate control of an aircraft. The internal system is linearized at the beginning of every horizon and RHC is applied for the resulting LTI model. The RHC controller contains integrators. The management of hard and soft constraints and the use of blocking parameters are elaborated. Simulation examples show the disturbance suppressing property of disturbance observer and the efficiency of high level RHC. For the indoor quadrotor helicopter, two (precise and simplified) dynamic models are derived. The sensory system contains on-board IMU and on-ground vision subsystems. A detailed calibration technique is presented for IMU. The vision system is based on motion-stereo and a special virtual camera approach. For state estimation, two level EKF is used. The quadrotor helicopter is controlled using backstepping in hierarchical structure. The embedded control system contains separate motor and sensor processors communicating through CAN bus with the main processor MPC555 realizing control and state estimation. Simulation results are shown first with MATLAB/Simulink then during the hardware-in-the-loop test of the embedded control system where the helicopter is emulated on dSPACE subsystem.