A Novel Nonlinear Backstepping Controller Design for Helicopters Using the Rotation Matrix

This brief presents a backstepping controller design for helicopters. The controller objective is for the helicopter to autonomously track predefined position and yaw reference trajectories. The incorporation of nested saturation feedback functions in the backstepping design preserves the helicopter's motion and power physical constraints. The intermediate control signals related to the attitude dynamics exploit the structural properties of the rotation matrix and are enhanced with terms that guarantee that the helicopter will not overturn while tracking the desired position trajectory. The attitude dynamics are rendered exponentially stable while the translational dynamics are globally asymptotically stable. Numerical simulations illustrate the applicability of the proposed design.