A Modified Super-Twisting Sliding Mode Control for Aircraft Braking System With Adaptive Gain Schedule and Disturbance Compensation

To overcome the adverse effects of time-varying parametric uncertainties and strong disturbances in aircraft antiskid braking systems (ABS), achieving efficient antiskid braking control and shortening the braking distance. This article proposes a modified super-twisting sliding mode control (MSSMC)-based aircraft ABS controller with gain adaptive schedule and disturbance compensation. In this article, MSSMC is obtained by substituting the discontinuous term in the conventional super-twisting sliding mode control (SSMC) with a continuous fractional power term, which can alleviate the chattering and improve the tracking performance. The developed controller is derived by effectively integrating MSSMC, extended state observer (ESO) and gain adaptive techniques, preserving the advantages of these approaches while effectively overcoming their practical performance limitations. The time-varying disturbances and unmodeled dynamics in aircraft ABS are estimated by ESO and compensated in a feedforward way, which significantly decreases the residual uncertainties handled by the MSSMC, thus alleviating the burden on the MSSMC and avoiding the high-gain feedback. In addition, a novel gain adaptive protocol for MSSMC is proposed, which can minimize the control gain and the chattering amplitude without the prerequisite of uncertain upper boundary required for conventional SSMC. Theoretical analysis based on the Lyapunov approach shows that the designed ABS controller ensures that the sliding variable converges to the desired accuracy near the origin in a finite time. Comparative experimental results demonstrate the effectiveness of the proposed approach.