Integral Sliding Mode Control of Steer by Wire System

Abstract

This thesis presents the design and simulation of an Integral Sliding Mode Controller (ISMC) for a Steer-by-Wire (SBW) system, aimed at achieving robust and precise steering control under uncertainties such as parameter variations, external disturbances, and varying road conditions. The proposed system tackles these challenges by integrating a sliding surface with an integral action, enhancing transient performance and disturbance rejection. The dynamic model of the SBW system, including actuator and steering mechanics, is explicitly developed prior to simulating the controller. The ISMC is formulated by designing a nominal control law based on the ideal dynamics of the SBW system, disregarding uncertainties. A switching control action is then incorporated to handle matched uncertainties, ensuring that performance criteria optimized under the nominal model remain unaffected. To further improve the system, a boundary layer is introduced to mitigate chattering, resulting in smooth and efficient control actions. Comparative analysis with Conventional Sliding Mode Control (SMC) demonstrates the ISMC's superior tracking accuracy, robustness, and ability to reject disturbances. MATLAB Simulink simulations confirm the effectiveness of the ISMC under various road conditions, including wet asphalt, snowy, and dry asphalt roads. Additionally, the asymptotic stability of the SBW system is verified using Lyapunov stability theory, ensuring the reliability of the proposed control strategy for modern automotive applications. The simulation results highlight the effectiveness of the proposed ISMC in maintaining precise and robust steering performance across diverse road conditions. The enhanced tracking accuracy, reduced chattering, and improved disturbance rejection capabilities demonstrate its potential for practical application in modern steer-by-wire systems. This study provides a strong foundation for further research and development, paving the way for advanced control strategies in next-generation automotive steering technologies