Reduced complexity rao-blackwellised particle

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Reduced-Complexity Rao-Blackwellised Particle Filtering for Fault Diagnosis Assoc.Prof.Dr. Peerapol Yuvapoositanon Centre of Electronic Systems Design and Signal Processing (CESdSP), Department of Electronic Engineering, Mahanakorn University of Technology, 140 Chemsampan Rd., Nong-Chok, Bangkok 10530, Thailand ISPACS 2011 1 Reduced-Complexity Rao-Blackwellised Particle Filtering for Fault Diagnosis

Transcript of Reduced complexity rao-blackwellised particle

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Reduced-Complexity Rao-Blackwellised Particle

Filtering for Fault Diagnosis

Assoc.Prof.Dr. Peerapol Yuvapoositanon

Centre of Electronic Systems Design and Signal Processing (CESdSP),

Department of Electronic Engineering,

Mahanakorn University of Technology,

140 Chemsampan Rd., Nong-Chok,

Bangkok 10530, ThailandISPACS 2011 1Reduced-Complexity Rao-Blackwellised

Particle Filtering for Fault Diagnosis

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What is a Fault?

• “A fault is an unpermitted deviation of at least one characteristic property (feature) of the system from the acceptable, usual standard condition.” 1

• In short, a fault is an undesired state within the system.

• A fault is meant to be promptly diagnosed.

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1 R. Isermann, Fault-Diagnosis Applications Model-Based Condition Monitoring: Actuators, Drives, Machinery, Plants, Sensors, and Fault tolerant Systems. Springer-Verlag Berlin Heidelberg, 2011.

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Example: Industrial Dryer

Rub´en Morales-Men´endez, Nando de Freitas and David Poole, Real-time monitoring of complex industrial processes with particle filters, in Neural Information Processing Systems, 2002, pp. 1433–1440.

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Faulty fan

Faulty grill

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Discrete States Assignment

• Normal operation corresponds to low fan speed, open air-flow grill and clean temperature sensor.

• Normal discrete state:

• Three types of faults :

Faulty fan

Faulty grill

Faulty fan and grill4Reduced-Complexity Rao-Blackwellised Particle

Filtering for Fault DiagnosisISPACS 2011

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State and Measurement Model

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The Dynamic Bayesian Network

Hidden Part

Observable Part

Control Part

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PF and RBPF

• Particle Filters (PFs) is a powerful state distribution estimation methodology for nonlinear-non Gaussian distribution.

• However, for discrete-state estimation like in fault diagnosis, the variance of PF is too high.

• Rao-Blackwellised Particle Filter (RBPF), a class of PFs that stems from the Rao-Blackwellised factorisation theorem, enjoys much less variance than PFs.

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Rao-Blackwellised Factorisation

Particle FilteringKalman Filtering

Analytical Density(Continuous state)

Reduced Space Density(Discrete state)

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RBPF Algorithm

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Reduced-Complexity RBPF

• RBPF uses Kalman filtering method in updating the mean and the covariance of every survived particle, which in turn requires enormous computational power.

• However, the particles in the same group have exactly the same statistical mean and covariance.

• Updating only one particle and using the results for all of the rest in the group is possible and is then proposed for RC-RBPF.

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Proposition 1

• Let TRC−RBPF and TRBPF be the time consumption required to complete each recursion t for the RC-RBPF and RBPF algorithms respectively. For any number of particles N,

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RC-RBPF Algorithm

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Simulation

• We investigated the time usages and predic-tion errors of the three algorithms over the range of one to 1,000 particles.

• Xeon CPU Dual Core 2.40 GHz with 8 GB RAM

• 64-bit Windows Server 2007 operating system.

• Each test was averaged over 100 Monte Carlo runs.

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Three-state Markovian transition matrix

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Three-state: Time Usage

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Three-state: Prediction Errors

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Six-state Markovian transition matrix

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Six-state: Time Usage

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Six-state: Prediction Errors

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Prediction percentage errors comparison for three states (nz = 3)

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Prediction percentage errors comparison for six states (nz = 6)

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Conclusions

• RC-BBPF is exactly RBPF.

• RC-RBPF has lower computational complexity.

• RC-RBPF is reverted to RBPF when the number of particles is small.

• The main point: Kalman updating step is performed to only one representative particle of a group particles gathering in a particular state.

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