Model-based active fault-tolerant control for a cryogenic combustion test bench

Abstract

In this paper a method is proposed to design a fault detection and isolation scheme based on quantitative physics-based models, as well as fault-tolerant control strategy to improve the reliability of a cryogenic combustion bench operation. The detection and isolation scheme is composed of an extended observer, a cumulative sum algorithm and an exponentially weighted moving average chart. In the case of interdependent parts, a dynamic parity space approach is proposed to isolate one or two simultaneous faults with constraints based on the mass flow rate continuity and the energy conservation for the overall system. The method allows settling adaptive thresholds that avoid pessimistic decision about the continuation of tests while detecting and isolating faults in the system. Then a fault-tolerant system reconfiguration mechanism is provided with a control law which compensates for an estimated actuator additive fault to maintain the overall system stability or allows converging to a reference state in order to overcome instabilities and take into account actuator saturations. For that purpose, the fault-tolerant control algorithm comprises a linear quadratic regulator, an unknown input observer to estimate the fault and an anti-windup scheme. The model and the estimation part were validated on real data from the ONERA/CNES MASCOTTE test bench, and the reconfiguration control law was validated in realistic simulations of the same system.