Adaptive and Interconnected Suspension Systems for Improving Truck Stability and Ride Quality

Abstract

Truck drivers are constantly exposed to undesirable vibrations caused by uneven road surfaces, especially in long-distance transportation. In addition to being at risk of repetitive motion injuries, drivers also suffer from fatigue, which in turn becomes a potential safety issue. As a way to resolve the issue, a truck is usually equipped with two suspension systems, namely the primary suspension and the secondary (cabin) suspension, in which the cabin suspension mainly acts as a vibration isolation system between the cabin and the rest of the vehicle. Different techniques have been applied to the cabin suspension to improve ride quality, stability, and safety. In most commercial vehicles, conventional passive suspensions are used that contain passive springs and dampers with fixed stiffness and damping properties. Nowadays, adaptive suspension systems are developed to further improve ride quality by dynamically controlling damping characteristics. Besides, interconnected suspension systems have been introduced to enhance the roll stability of the sprung mass and provide better handling and ride quality simultaneously. As a result, this study aims to improve truck drivers’ ride comfort and stability by developing semi-active and interconnected suspension systems. A semi-active cabin suspension system is developed based on different multi-objective optimal control approaches to attenuate the vertical, roll, and pitch vibrations transmitted to the cabin. The Model Predictive Control (MPC) is chosen as the benchmark because of its superior performance in handling constraints and prediction, although its high computational costs make it difficult to be implemented in suspension applications. To solve this issue, a novel integrated Skyhook-LQR (Linear Quadratic Regulator) control approach is introduced to take advantage of both Skyhook and LQR while its computational cost is low enough for real-time implementation in suspension control tasks. In addition, two gain-adaptive algorithms are proposed to intelligently adjust the control gains according to the disturbance inputs and/or vehicle states based on onboard sensor measurements. Two novel interconnected suspension systems are designed to minimize the harsh rotational motions during braking or turning maneuvers, namely AIS-ARS and AIS-ARPS. Both configurations have adaptive damping and adjustable rotational stiffness characteristics, which provide excellent vibration attenuation and attitude control performances. All the proposed suspension systems and their mathematical models are examined and validated through laboratory experiments and co-simulations between ADAMS/Car and MATLAB/Simulink.