Influence of Intelligent Active Suspension System Controller Design Techniques on Vehicle Braking Characteristics

This article presents a comprehensive investigation for the interaction between vehicle ride vibration control and braking control using two degrees of freedom (2DOF) quarter vehicle model. A typical limited bandwidth active suspension system with nonlinear spring and damping characteristics of practical hydraulic and pneumatic components is controlled to regulate both suspension and tire forces and therefore provide the optimum ride comfort and braking performance of an anti-lock braking system (ABS). In order to design a suitable controller for this nonlinear integrated system, various control techniques are followed including state feedback tuned using Linear Quadratic Regulator (LQR), state feedback tuned using Genetic Algorithm (GA), Proportional Integral (PI) tuned genetically, and Fuzzy Logic Control (FLC). The ABS control system is designed to limit skid ratio below threshold of 15%. Several simulations are carried out in MATLAB environment to assess the benefits of the designed integrated controller including vehicle body vertical acceleration, dynamic tire load, stopping time, and distance. Furthermore, the proposed control techniques have been examined in terms of robustness, disturbance rejection, and noise attenuation. The obtained results revealed that the nonlinear assumptions of hydraulic and pneumatic suspension system components are notably influenced by the braking performance in terms of stopping time and distance which has successfully justified the aimed research topic. The effectiveness and robustness of the proposed controllers are discussed based on the simulation results which confirmed their significant improvements in both braking and ride characteristics.