Command-Filtered Incremental Backstepping Controller for Small Unmanned Aerial Vehicles

A command-filtered incremental backstepping method for handling uncertainties and unknown actuator dynamics is studied. The proposed novel incremental backstepping applies incremental nonlinear dynamic inversion for each subsystem to increase the robustness of the system. Additionally, the stable linear filter is improved so that the compensating signals converge to a small neighborhood around the origin, even under the condition of actuator biases and measurement noises, biases, and time delays of the control surface deflection angles. The compensated terms are designed to eliminate the effects of the measurement values of the control surface deflection angles. It is demonstrated that noise, biases, time delays, and other practical problems related to the measurement values of the control surface deflection angles have no immediate effects on the dynamics of the compensated tracking errors. The simulation results illustrate the robustness of the proposed method and indicate that the selection of the filter introduced in the compensated section is flexible and does not strongly depend on the actuator dynamics.