Independent Observers-Based Fault Diagnosis for Multiple Sensor Faults of Full-Vehicle Active Suspension Systems With Inaccurate Models

In this paper, an independent observers-based fault diagnosis method is proposed for multiple sensor faults of the full-vehicle active suspension system with an inaccurate model.To address the problem of model uncertainties brought by the linearized full-vehicle suspension model, unmodelled dynamics,parametric uncertainties, and external disturbances are first com-bined into an integrated uncertain term. Disturbance observers are designed to online track the integrated uncertain terms,whose estimates will be employed to decrease the influence of model uncertainties on fault diagnosis. An independent fault diagnosis observer is designed for each sensor separately, where only the measurement of the matched sensor is taken as the observer input. In this way, each fault diagnosis observer works independently and interactions between measurements of multi-ple faulty sensors can be decoupled to locate the sensor faults.Anomalies of each sensor are monitored by the fault diagnosis observer in a one-to-one relationship such that fault detection and isolation can be realized at the same time. In particular,the sensitivity and robustness of the fault diagnosis method are improved with the estimates of the integrated uncertain terms injected into the fault diagnosis observers to emulate model uncertainties. Effectiveness of the proposed scheme has been validated via simulation results considering multiple sensor faults occurring at different time or simultaneously.