Real-time implementation of an Integral Sliding Mode Fault Tolerant Control scheme for LPV plants

Abstract

This paper proposes a fault tolerant control scheme for linear parameter varying systems based on integral sliding modes and control allocation, and describes the implementation and evaluation of the controllers on a 6 degree-of-freedom research flight simulator called SIMONA. The fault tolerant control scheme is developed using a linear parameter varying approach to extend ideas previously developed for linear time invariant systems, in order to cover a wide range of operating conditions. The scheme benefits from the combination of the inherent robustness properties of integral sliding modes (to ensure sliding occurs throughout the simulation) and control allocation, which has the ability to redistribute control signals to all available actuators in the event of faults/failures. Index TermsSliding mode control, Fault tolerance, Aerospace simulation. I. INTRODUCTIONThe most important facet of Fault Tolerant Control (FTC) systems is their ability to maintain closed-loop stability, and ideally a measure of performance, in the face of faults or failures in actuators or sensors. The majority of the FTC methods that have appeared in the literature are based on linear time invariant (LTI) systems (see for example [1]). There are however notable exceptions: for example an observer based scheme for a specific class of input-output stable nonlinear systems is proposed in [2]; a passive FTC approach is proposed in [3] for a class of affine nonlinear systems considering actuator faults; and in [4], a FTC scheme for a specific class of nonlinear systems is proposed based on a sliding mode control allocation scheme incorporating a backstepping controller.Linear parameter varying (LPV) systems are a special class of finite dimensional linear systems, in which the entries of the state space matrices continuously depend on a time varying parameter vector which belongs to a bounded compact set. Using LPV techniques, the control law can be automatically 'scheduled' with the operating conditions and guaranteed performance can be proved over a wide operating envelope. FDI and FTC methods designed for LPV models have appeared in the literature. In [5], a synthesis method using LMIs is presented in order to guarantee closed-loop stability in the case of multiple actuator faults. In [6] an FDI scheme based on the extension of residual generation concepts for LTI systems was presented and tested on a model of a B747-100/200.Sliding mode control (SMC) is attractive from an FTC stand point, since actuator faults can be modelled as matched uncertainty, which is precisely the class of uncertainty to which sliding modes are robust [7]. However SMC cannot directly deal with total actuator failures because the complete loss of effectiveness in a channel destroys the regularity of the sliding mode, and an unique equivalent control signal can no longer be determined. To obviate this short-coming, in over actuated systems, a combination of SMC and control allocation (CA) has recently been explored [8]. In this context, CA can be viewed a...

Real-time fault diagnosis and fault-tolerant control

“…As a result, active fault tolerant control techniques mostly reply on realtime fault diagnosis schemes to provide the up-to-date information on the current status of the system monitored. Undoubtedly, the selected papers [22][23][24][25][26][27][28][29][30][31] fall into the category of active fault tolerant control as they are all heavily dependent of the system status information provided by the fault diagnosis schemes. The paper [32] is not based directly on the diagnosis of the faults, but on the compensation of the ultimate impact caused by the faults by using adaptive control laws.…”

“…The paper [24], contributed by Alwi et al, presents a fault tolerant control scheme for linear parameter varying systems using integral sliding modes and control allocation. The integral sliding mode approach ensures ideal sliding throughout the closed-loop system response and maintains nominal performance and robustness in the face of possible actuator faults/failures.…”

“…Twelve selected papers pay attention on fault diagnosis methods and applications [10][11][12][13][14][15][16][17][18][19][20][21], and the other eleven papers are concentrated on real-time fault tolerant control and applications [22][23][24][25][26][27][28][29][30][31][32]. We are going to overview the selected papers following fault diagnosis techniques and fault-tolerant control techniques sequentially.…”

Constrained control allocation for nonlinear systems with actuator failures or faults

“…To eliminate the reaching phase, an integral sliding mode control (ISMC) was proposed in [14]. To deal with fault, combinations of the CA with ISM are used in [15,16] for linear systems. The integral action has deficiencies, like large overshoot and long settling time.…”

Application of model-based LPV actuator fault estimation for an industrial benchmark

“…Recently, the application of linear parameter varying (LPV) concepts to system modelling, control and FDD have also received much attention (Balas, 2002;Bokor & Balas, 2004;Henry, 2008;Sato, 2010;Wei & Verhaegen, 2011a;Hecker & Pfifer, 2014;Alwi & Edwards, 2014;Henry et al, 2014;Varga & Ossmann, 2014;Vanek et al, 2014;Chen et al, 2016;Rodonto et al, 2015;Ossmann & Varga, 2015;Rotondo et al, 2015;Alwi et al, 2015). Nevertheless, the technical demands of model-based FDD, especially for the FDD problem based on using LPV, are still quite limited and restrictive in the aerospace industry (Zolghadri, 2012).…”