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A deep learning scheme for mental workload classification based on restricted Boltzmann machines

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Abstract

The mental workload (MWL) classification is a critical problem for quantitative assessment and analysis of operator functional state in many safety-critical situations with indispensable human–machine cooperation. The MWL can be measured by psychophysiological signals. In this work, we propose a novel restricted Boltzmann machine (RBM) architecture for MWL classification. In relation to this architecture, we examine two main issues: the optimal structure of RBM and selection of the most important EEG channels (electrodes) for MWL classification. The trial-and-error and entropy-based pruning methods are compared for the RBM structure identification. The degree of importance of EEG channels is calculated from the weights in a well-trained network in order to select the most relevant channels for classification task. Extensive comparative results showed that the selected EEG channels lead to accurate MWL classification across subjects.

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Abbreviations

MWL:

Mental workload

OFS:

Operator functional state

RBM:

Restricted Boltzmann machine

DBN:

Deep belief network

EEG:

Electroencephalogram

EOG:

Electrooculogram

ECG:

Electrocardiogram

MAD:

Mean absolute difference

aCAMS:

Automation-enhanced Cabin Air Management System

MPF:

Mean power–frequency

SE:

Sample entropy

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Acknowledgements

This work was supported in part by the National Natural Science Foundation of China under Grant No. 61075070 and Key Grant No. 11232005. The authors would like to thank the developers of the aCAMS software used in our experiments.

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Correspondence to Jianhua Zhang.

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Zhang, J., Li, S. A deep learning scheme for mental workload classification based on restricted Boltzmann machines. Cogn Tech Work 19, 607–631 (2017). https://doi.org/10.1007/s10111-017-0430-6

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