Non-overshooting sliding mode for UAV control

TL;DR

This paper introduces a non-overshooting sliding mode control method for UAVs that ensures stable, overshoot-free trajectory tracking even under uncertainties and disturbances, validated through real flight tests.

Contribution

It develops a novel second-order sliding mode control with bounded gains for global non-overshooting stability in UAVs, including a chattering-reduction technique.

Findings

Successful UAV trajectory tracking without overshoot

Robust stability under stochastic disturbances

Effective chattering mitigation with tanh-function-based sliding mode

Abstract

For a class of uncertain systems, a non-overshooting sliding mode control is presented to make them globally exponentially stable and without overshoot. Even when the unknown stochastic disturbance exists, and the time-variant reference trajectory is required, the strict non-overshooting stabilization is still achieved. The control law design is based on a desired second-order sliding mode (2-sliding mode), which successively includes two bounded-gain subsystems. Non-overshooting stability requires that the system gains depend on the initial values of system variables. In order to obtain the global non-overshooting stability, the first subsystem with non-overshooting reachability compresses the initial values of the second subsystem to a given bounded range. By partitioning these initial values, the bounded system gains are determined to satisfy the robust non-overshooting stability. In order to reject the chattering in the controller output, a tanh-function-based sliding mode is developed for the design of smoothed non-overshooting controller. The proposed method is applied to a UAV trajectory tracking when the disturbances and uncertainties exist. The control laws are designed to implement the non-overshooting stabilization in position and attitude. Finally, the effectiveness of the proposed method is demonstrated by the flying tests.