Safe-parking of nonlinear process systems

Gandhi, R.; Mhaskar, Prashant

doi:10.1109/acc.2008.4586702

Cited by 15 publications

(43 citation statements)

References 17 publications

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“…Although there has been significant work on fault detection and isolation for batch processes, [25][26][27][28][29] faulttolerant control structures (FTCS) specific to batch systems have received limited research attention. The majority of the extensive research on FTCS for continuous processes 30 including recent results that address how to operate a plant during temporary faults 31 cannot be applied to batch processes because of the absence of equilibrium points and fundamental differences in the control objectives between batch and continuous processes. 4 As is the case for continuous processes, the majority of the FTCS for batch processes 8,32 essentially rely on the robustness of the control design to handle faults as disturbances during the failure period.…”

Section: Introductionmentioning

confidence: 99%

Robust model predictive control and fault handling of batch processes

Aumi

Mhaskar

2010

AIChE J.

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This work considers the control of batch processes subject to input constraints and model uncertainty with the objective of achieving a desired product quality. First, a computationally efficient nonlinear robust Model Predictive Control (MPC) is designed. The robust MPC scheme uses robust reverse-time reachability regions (RTRRs), which we define as the set of process states that can be driven to a desired neighborhood of the target end-point subject to input constraints and model uncertainty. A multilevel optimization-based algorithm to generate robust RTRRs for specified uncertainty bounds is presented. We then consider the problem of uncertain batch processes subject to finite duration faults in the control actuators. Using the robust RTRR-based MPC as the main tool, a robust safe-steering framework is developed to address the problem of how to operate the functioning inputs during the fault repair period to ensure that the desired end-point neighborhood can be reached upon recovery of the full control effort. The applicability of the proposed robust RTRR-based controller and safe-steering framework subject to limited availability of measurements and sensor noise are illustrated using a fed-batch reactor system.

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Section: Introductionmentioning

confidence: 99%

Robust model predictive control and fault handling of batch processes

Aumi

Mhaskar

2010

AIChE J.

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“…Proactive FTMPC schemes may also be put in context of safe-parking techniques for process plants, see e.g. Gandhi and Mhaskar (2008). These methods are, however, reactive FTC approaches.…”

Section: Introductionmentioning

confidence: 99%

Proactive Actuator Fault-Tolerance in Economic MPC for Nonlinear Process Plants**The author gratefully acknowledge support from NFR grant 228460/030 and from Cybernetica AS.

Knudsen

2016

IFAC-PapersOnLine

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Abstract:This paper presents a scheme for proactive accommodation of incipient actuator faults in nonlinear process plants operated with economic model predictive control (EMPC). The control scheme implements a switching from nominal economic operations to a safe-transition mode when receiving a warning about an incipient fault in one of the actuators, thereby ensuring that the plant is proactively steered to a steady-state point where the suspect control actuator is inactive. Upon reaching this safe steady-state point, the faulty actuator can be safely disconnected and repaired without shutting down the plant, before the controller subsequently resumes nominal economic operation. To steer the plant to the safe steady-state point, we impose an 1 penalty function in order to achieve dead-beat control and reach the steady state in finite time. We provide a lower bound on the penalty parameter to ensure exactness of the penalty function, and analyze stability and convergence properties of the proactive fault-tolerant EMPC scheme. We demonstrate application of the proposed scheme on a non-isothermal continuously stirred tank reactor.

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“…The remaining conditions dictating the choice of a safe-park point follow from the safe-parking framework designed for a fail-safe position in [10]. In particular, to make sure that the system can be driven to the temporary operating point, it requires that the system state should reside within the stability region of the safe-park point at the time of fault confirmation.…”

Section: Remarkmentioning

confidence: 99%

“…To handle faults that preclude the possibility of nominal operation, a safe-parking framework has recently been proposed for an isolated unit [10] and studied in the context of a plant-wide setting [11]. More recently, it has been generalized to handle faults in switched nonlinear systems [12].…”

Section: Introductionmentioning

confidence: 99%

Integrated fault diagnosis and robust safe-parking for fault-tolerant control of nonlinear systems

Nease

Mhaskar

2011

Proceedings of the 2011 American Control Conference

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Abstract-In this work, we consider the problem of fault diagnosis and fault-handling for nonlinear systems subject to actuator faults. A model-based fault diagnosis scheme is proposed, which can not only identify the failed actuator, but also estimate the magnitude of the fault. With the aid of the fault diagnosis design, the safe-parking framework for fault-tolerant control is extended to handle the case where an actuator seizes at an arbitrary position. The efficacy of the proposed framework is demonstrated through a chemical reactor example.

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Safe-parking of nonlinear process systems

Cited by 15 publications

References 17 publications

Robust model predictive control and fault handling of batch processes

Robust model predictive control and fault handling of batch processes

Proactive Actuator Fault-Tolerance in Economic MPC for Nonlinear Process Plants**The author gratefully acknowledge support from NFR grant 228460/030 and from Cybernetica AS.

Integrated fault diagnosis and robust safe-parking for fault-tolerant control of nonlinear systems

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