Fault Tolerant Control Based on a Moving Horizon Virtual Actuator with Target Tracking

Rafael R. Sencio, Flávio V. da Silva, and Thiago V. da Costa

Keywords

fault tolerant control, reconfigurable control, disturbance estimation, moving horizon, virtual actuator

Abstract

Because control systems are highly connected, defects in actuators, sensors or within the controller may affect other instances of the system, resulting in malfunction of the control loop as a whole. Therefore, an essential concern, specially for highly complex modern plants, is to prevent an unexpected change in a system component from compromising process performance or cause safety hazards. One way of avoiding these situations is to apply a fault tolerant strategy to the system. This work is based on the fault hiding and virtual actuator approaches. A moving horizon framework is used for the virtual actuator implementation in conjunction with a target calculator and a state and disturbance estimator based on an augmented post-fault model. The proposed reconfiguration block is capable of computing steady state targets that are achievable after the occurrence of fault in the system, especially when there are no analytical or physical redundancies available. Moreover, this approach aims to deal with cases when the fault identification system provides imperfect post-fault model. This paper presents simulations of the proposed control reconfiguration technique against stuck actuator faults in a pH neutralization process.

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