Fault-tolerant Control System Design and Analysis · 2 Outline of the presentation! Overview of two...
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3/10/2003 1 Fault-tolerant Control System Design and Analysis Jin Jiang Department of Electrical and Computer Engineering The University of Western Ontario London, Ontario N6A 5B9 Canada
Transcript of Fault-tolerant Control System Design and Analysis · 2 Outline of the presentation! Overview of two...
3/10/2003 1
Fault-tolerant Control System Design and Analysis
Jin Jiang
Department of Electrical and Computer Engineering
The University of Western Ontario
London, Ontario N6A 5B9
Canada
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Outline of the presentation
! Overview of two approaches to fault-tolerant control system design and analysis
! Redundancy in fault-tolerant control systems! Trade-offs among redundancy, performance and
integrity
! An example of passive fault-tolerant control design
! An example of active fault-tolerant control design
! Some open problems
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Fault-tolerant control: An overview
! Passive fault-tolerant control systems! Robust fixed structure controller! Faults have been considered at the controller design stage
! Active fault-tolerant control systems! Explicit fault detection/diagnosis schemes! Real-time decision-making and controller reconfiguration
! The key to any fault-tolerant control system ! Redundancy
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Passive fault-tolerant control systems
ControllerOutputs
Actuator System
Sensor
L-
faults
faults
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Active fault-tolerant control systems
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Features and limitations
! Passive fault-tolerant control systems! Simple to implement! Difficult to account for large number of fault scenarios! Unable to deal with unforeseen faults
! Active fault-tolerant control systems! Potentially be able to deal with a large number of fault
scenarios ! Can deal with certain number of unforeseen faults! More complex to implement! Real challenge is real-time decision-making
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Redundancies
! Actuator redundancies! Multiple physical actuators• They usually act on the system at different locations
! Sensor redundancies! Multiple physical sensors• They usually measure the same physical quality
! Analytical redundancies! Rely on mathematical models (FDI)
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Actuator redundancies
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Actuator Redundancies
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Definitions of actuator redundancies
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Sensor redundancies
A1
A2
A3
Am
SystemDynamics
S11
S12
S21
S22
S2q
Sp1
Sp2
Spq
S1q
......
....
u1
u2
u3
um
y1
y2
yp
Actuator Inputs System Inputs System Outputs
Sens
or O
utpu
ts
1
2
p
zp1
zp2
zpq
....
....
....
z21
z22
z2q2
p
z12
z11
z1q1
....
....
....
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Analytical Redundancies
System ........
Analytical model
Inpu
ts
Out
puts
Intermediate system variables
SensorsRedundant system output
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Performance trade-offs
Three main factors to consider in any fault-tolerant control system design:
System Integrity (safety requirements)Performance (design specifications)Redundancy (physical and financial constraints)
Problem: How to design a control system, under a given degree of redundancy such that the integrity of the system is guaranteed and the performance is satisfactory.
Issue 1: System integrity should always be maintainedIssue 2: Faults should result in reduction of the degree of redundancy firstIssue 3: One should consider performance degradation with available
redundancies.
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Example of passive fault-tolerant control system
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Description of system
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Control system performance
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Control system performance
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Example of active fault-tolerant control system
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Simulation results
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Simulation results
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Simulation results
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Simulation results
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Some open problems
! Reliability analysis of fault-tolerant control systems
! Stability analysis of fault-tolerant control systems
! Graceful performance degradation! Integration of passive and active approaches! Industrial applications of fault-tolerant control
system technologies
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Thank You !
