• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2026, Vol. 62 ›› Issue (8): 85-99.doi: 10.3901/JME.260215

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Hierarchical Fault-tolerant Control Strategy for Actuator Failures in Automotive Active Suspension Systems

WANG Zi1,2, BAI Xianxu1,2, LI Jie1,2, SUN Jun1,2   

  1. 1. School of Automotive and Transportation Engineering, Hefei University of Technology, Hefei 230009;
    2. Laboratory for Adaptive Structures and Intelligent Systems (LASIS), Hefei University of Technology, Hefei 230009
  • Received:2025-05-09 Revised:2025-11-10 Online:2026-04-20 Published:2026-06-12

Abstract: A hierarchical fault-tolerant control strategy for active suspension is proposed to mitigate the increased risk of vehicle instability caused by actuator faults under complex operating conditions. The strategy is concerned on maintaining vehicle body attitude stability and is composed of a vehicle-body layer, a force-distribution layer, and an execution layer. The vehicle-body layer computes the required body control forces based on vehicle states; the force-distribution layer allocates target control forces to individual suspensions according to the body control force requirement; the execution layer issues suspension control commands to realize the prescribed forces. A fault-diagnosis observer is first designed to monitor the health status of the suspension actuators. Fault-tolerant control is then implemented based on the observer outputs. Under multi-actuator partial-failure conditions, a dynamic master-force-distribution method is developed, whereby force allocation coefficients are adjusted in the force-distribution layer according to the diagnostic results. Under single-actuator total-failure conditions, a three-actuator optimal fault-tolerant control method is formulated: vehicle body control forces are solved by an optimal control algorithm subject to the remaining actuators' force output ranges, and the allocation matrix is reconstructed in the force-distribution layer. At the execution layer, sliding-mode controllers are designed to robustly track each suspension's control force target. Simulation results show that, compared with conventional fault-tolerant control, the proposed methods improve vehicle stability: when multiple suspension actuators partially fail, the dynamic master-force-distribution method reduces actuation by the faulty suspensions and decreases the maximum body vertical displacement, pitch angle, and roll angle by 28.5%, 22.8%, and 34.2%, respectively. When a single suspension actuator completely fails, the three-actuator optimal fault-tolerant control method, which accounts for actuator output limits, suppresses body vertical vibration and reduces the maximum body vertical displacement and roll angle by 35.9% and 38.2%, respectively.

Key words: full-vehicle suspension, actuator faults, fault-tolerant control, hierarchical control architecture, optimal control

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