Design and Comparative Analysis of Multiple MIMO Controllers for a Half-Car Suspension System

This paper investigates the design of multiple-input multiple-output (MIMO) controllers for a half-car suspension system, aiming to enhance ride quality by minimizing displacement and angular deviations. The nonlinear equations describing the half-car model are derived, incorporating control inputs and road disturbances. The study explores centralized, decentralized, and semi-centralized (sequential) control strategies using proportional-integral (PI), proportional-integral-derivative (PID), and H_∞ robust control techniques. The centralized PI and H_∞ controllers are designed using Markov parameters and sensitivity weighting functions, respectively. In the decentralized approach, control designs involve inverse decoupling, state feedback decoupling, PID tuning against disturbances, and mixed-sensitivity H_∞ optimization. The semi-centralized strategy sequentially closes control loops using a PID architecture. Extensive simulations are conducted with step and road bump disturbance inputs applied to the closed-loop system. Controller performance is evaluated based on displacement suppression, control effort, settling time, and robustness to external shocks. The proposed decentralized H_∞ controller achieves superior vibration attenuation to the picometer level while exhibiting strong disturbance rejection capabilities. The comparative analysis underscores the advantages of the developed control schemes over existing solutions, contributing to enhanced passenger comfort in automotive suspension systems.