Active and Semi-Active Suspension Systems for Off-Road Vehicle Dynamics: A Comprehensive Review

This study presents a comprehensive investigation into advanced suspension technologies for off-road vehicles, with a particular focus on active and semi-active systems and their associated control strategies. Off-road vehicles operate under highly variable and unpredictable terrain conditions, where maintaining ride comfort, vehicle stability, and tire–ground contact becomes critically challenging. Traditional passive suspension systems, while robust and mechanically simple, are inherently limited by fixed stiffness and damping characteristics, restricting their ability to adapt to dynamic environments. The report examines the fundamental limitations of conventional suspension systems and explores the evolution toward semi-active and fully active suspension architectures. Key enabling technologies, including magnetorheological (MR) dampers, electronically controlled actuators, and sensor-integrated systems, are analyzed in detail. Special attention is given to the role of real-time control algorithms in enhancing suspension performance. A range of control strategies is systematically reviewed, including Skyhook and Groundhook control, adaptive control methods, model predictive control (MPC), and AI-based approaches such as fuzzy logic and machine learning. These strategies are evaluated in terms of their effectiveness in balancing ride comfort, handling stability, and traction across complex off-road terrains. The study also discusses the integration of suspension control with broader vehicle dynamics systems such as Electronic Stability Control (ESC) and traction control. Furthermore, the report highlights emerging trends in intelligent suspension systems, including the application of machine learning for terrain classification and decision-making, as well as regenerative suspension technologies aimed at improving energy efficiency. The potential of adaptive suspension systems in electric off-road vehicles is also explored, considering their unique powertrain characteristics and control opportunities. Despite the significant performance improvements offered by advanced suspension systems, the study critically addresses existing challenges, including system complexity, energy consumption, sensor reliability, and real-time computational constraints in harsh environments. Overall, this work provides a structured and technically grounded overview of modern suspension system design for off-road applications, emphasizing the transition from purely mechanical solutions toward intelligent, data-driven, and adaptive vehicle systems.