Robust multiactuator fault‐tolerant MPC design for constrained systems

Abstract

SUMMARYIn this paper, we present a robust actuator fault‐tolerant control strategy for constrained linear systems in the presence of bounded state and input disturbances. The scheme is based on a bank of state estimators that match different fault situations that can occur in the system. A fault detection and isolation unit verifies that suitable residual variables lie inside pre‐computed sets and selects the estimate that matches the current plant behaviour. A bank of robustly stabilizing tube‐based model predictive control laws is designed, each associated to a fault scenario, and the appropriate controller is selected among them by using the information provided by the fault detection and isolation module. By means of ‘tubes’ of trajectories, we ensure robust closed‐loop exponential stability of the constrained system and good performance in the fault‐free case and under the occurrence of abrupt actuator faults, including actuator outage and loss of effectiveness by an unknown amount. Copyright © 2012 John Wiley & Sons, Ltd.

Actuator Fault Tolerant Control: A Receding Horizon Set-Theoretic Approach

“…We present results on the effectiveness of the proposed AFTC-RHC strategy and make comparisons with the FTC scheme of [15] both in terms of fault detectability capabilities and control performance.…”

“…Specifically, two tanks with levels h 1 and h 2 are interconnected through lower and upper valves, u L and u U , and the first tank is filled via a pump input command u P . By defining the state x = [h 1 h 2 ] T and the input vector u = [u P u L u U ] T , the linearized model is described by the following matrices: The FTC algorithm of [15] has been implemented by using an horizon length N c = 5. All the numerical results are summarized in the next Figs.…”

“…Of interest here are the results from [14] and [15] where a set-theoretic approach for designing MPC sensor-based FTC schemes are proposed. In these contributions, the idea relies on the separation of "healthy" attractive invariant sets, where appropriate fault residual signal variables remain under healthy operations, from "under-fault" sets which instantaneously capture the behaviour of the residuals when abrupt faults occur in one or more groups of sensors.…”

“…Finally, simulations on an interconnected tank system provide comparisons with the recent MPC-based FTC scheme of Yetendje et al [15] under the occurrence of critical faults.…”

Sensor fault tolerance in output feedback nonlinear model predictive control

“…The majority of FTMPC schemes are active faulttolerant control (FTC) schemes, based on reconfiguration of the internal MPC model, the constraints or the objective function subject to fault in an actuator (e.g. [3], [4], [5]) or in a sensor [6], [7]. FTMPC schemes may also be designed using a passive approach, thus relying on robustness of the MPC controller, see e.g.…”