4,745 research outputs found
Fault-tolerant control under controller-driven sampling using virtual actuator strategy
We present a new output feedback fault tolerant control strategy for
continuous-time linear systems. The strategy combines a digital nominal
controller under controller-driven (varying) sampling with virtual-actuator
(VA)-based controller reconfiguration to compensate for actuator faults. In the
proposed scheme, the controller controls both the plant and the sampling
period, and performs controller reconfiguration by engaging in the loop the VA
adapted to the diagnosed fault. The VA also operates under controller-driven
sampling. Two independent objectives are considered: (a) closed-loop stability
with setpoint tracking and (b) controller reconfiguration under faults. Our
main contribution is to extend an existing VA-based controller reconfiguration
strategy to systems under controller-driven sampling in such a way that if
objective (a) is possible under controller-driven sampling (without VA) and
objective (b) is possible under uniform sampling (without controller-driven
sampling), then closed-loop stability and setpoint tracking will be preserved
under both healthy and faulty operation for all possible sampling rate
evolutions that may be selected by the controller
Reliable fault-tolerant model predictive control of drinking water transport networks
This paper proposes a reliable fault-tolerant model predictive control applied to drinking water transport networks. After a fault has occurred, the predictive controller should be redesigned to cope with the fault effect. Before starting to apply the fault-tolerant control strategy, it should be evaluated whether the predictive controller will be able to continue operating after the fault appearance. This is done by means of a structural analysis to determine loss of controllability after the fault complemented with feasibility analysis of the optimization problem related to the predictive controller design, so as to consider the fault effect in actuator constraints. Moreover, by evaluating the admissibility of the different actuator-fault configurations, critical actuators regarding fault tolerance can be identified considering structural, feasibility, performance and reliability analyses. On the other hand, the proposed approach allows a degradation analysis of the system to be performed. As a result of these analyses, the predictive controller design can be modified by adapting constraints such that the best achievable performance with some pre-established level of reliability will be achieved. The proposed approach is tested on the Barcelona drinking water transport network.Postprint (author's final draft
Software dependability modeling using an industry-standard architecture description language
Performing dependability evaluation along with other analyses at
architectural level allows both making architectural tradeoffs and predicting
the effects of architectural decisions on the dependability of an application.
This paper gives guidelines for building architectural dependability models for
software systems using the AADL (Architecture Analysis and Design Language). It
presents reusable modeling patterns for fault-tolerant applications and shows
how the presented patterns can be used in the context of a subsystem of a
real-life application
Advanced flight control system study
The architecture, requirements, and system elements of an ultrareliable, advanced flight control system are described. The basic criteria are functional reliability of 10 to the minus 10 power/hour of flight and only 6 month scheduled maintenance. A distributed system architecture is described, including a multiplexed communication system, reliable bus controller, the use of skewed sensor arrays, and actuator interfaces. Test bed and flight evaluation program are proposed
Damage Tolerant Active Contro l: Concept and State of the Art
Damage tolerant active control is a new research area relating to fault tolerant control design applied to mechanical structures. It encompasses several techniques already used to design controllers and to detect and to diagnose faults, as well to monitor structural integrity. Brief reviews of the common intersections of these areas are presented, with the purpose to clarify its relations and also to justify the new controller design paradigm. Some examples help to better understand the role of the new area
Improving reconfigurable systems reliability by combining periodical test and redundancy techniques: a case study
This paper revises and introduces to the field of reconfigurable computer systems, some traditional techniques used in the fields of fault-tolerance and testing of digital circuits. The target area is that of on-board spacecraft electronics, as this class of application is a good candidate for the use of reconfigurable computing technology. Fault tolerant strategies are used in order for the system to adapt itself to the severe conditions found in space. In addition, the paper describes some problems and possible solutions for the use of reconfigurable components, based on programmable logic, in space applications
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