Identification and Accommodation of Control Actuator Faults Using Multi-rate Sampled Measurements

• Published in: IFAC-PapersOnLine Vol. 52; no. 1; pp. 305 - 310
• Main Authors: Allen, James T., El-Farra, Nael H.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2019
• Subjects: Actuator faults; Fault accommodation; Fault estimation; Model-based control; Multi-rate sampling; Multi-rate sampling; Fault estimation; Fault accommodation; Actuator faults; Model-based control
• ISSN: 2405-8963; 2405-8963
• DOI: 10.1016/j.ifacol.2019.06.079

This work presents a model-based approach for the detection, estimation and accommodation of control actuator faults in dynamic processes controlled using multi-rate sampled state measurements. Initially, a model-based state feedback controller that employs an inter-sample model predictor to compensate for the unavailability of continuous state measurements is designed. Characterizations of both the stability and performance properties of the multi-rate sampled-data closed-loop system are obtained and expressed in terms of the measurement sampling rates, the magnitudes of the faults, and the various predictor and controller design parameters. A parameter estimator that estimates the magnitudes of the faults by minimizing the error between the estimated and sampled states over a moving horizon is then introduced and used to determine the fault or health status of the control actuators at the sampling times. The identification of faults triggers a fault accommodation scheme that adjusts selected predictor and controller design parameters to simultaneously preserve closed-loop stability and optimize a pre-defined performance metric. The implementation of the developed approach is illustrated using a simulated model of a solid oxide fuel cell system subject to both stability and performance-degrading actuator faults. A discussion of some of the intricacies of the multi-rate sampling scheme and how they impact the practical implementation of the fault identification and accommodation schemes is presented.