Coordinated control of active safety systems for multi-trailer articulated heavy vehicles

Abstract

To improve the directional performance of multitrailer articulated heavy vehicles (MTAHVs), the model-based active safety systems, including the active trailer steering, trailer differential braking and the active roll control are developed. The active safety systems are integrated and coordinated for optimal overall performance. The coordinated control system is designed in a modular, hierarchical and multilevel approach. At the upper level, a moment controller is designed to stabilize the yaw and the roll dynamics. At the intermediate level, an allocator is designed to distribute the demanded moments to the actuating systems. At the lower level, the active suspension system realizes the demanded roll moment, and the active trailer steering and the trailer differential braking share the demanded yaw moment. The directional performance of the MTAHV with the coordinated control system is evaluated in closed-loop simulations. A unified driver model for road vehicles is developed to ‘drive’ the vehicle in the closed-loop simulations. Considering the characteristics of the single unit and the multiunit vehicle drivers, a set of design parameters are introduced to govern the characteristics of the driver model to mimic human drivers in driving single unit and multiunit road vehicles, especially to simulate MTAHV drivers’ driving performance under a high-speed evasive and a low-speed path-following maneuvers, respectively. The directional performance of the MTAHV with the coordinated control system and the driver model may be valuated and optimized using a genetic algorithm with the performance measures in the time-domain and the frequency-domain, thanks to the introduction of the automated frequency response measuring method (AFRM) into the articulated heavy vehicle dynamics. The proposed design methods/techniques and findings derived from the research will contribute to the advancement of active safety systems for MTAHVs.