Deep discriminative sparse representation learning for machinery fault diagnosis

The high complexity of actual machinery vibration environments introduces various interferences into vibration signals, making it challenging to eliminate redundant information and extract discriminative features of mechanical faults. Shallow-structured sparse classification models enable intelligent fault diagnosis but struggle with deeper feature extraction, especially in small-sample cases. In this paper, we introduce a deep discriminative sparse representation learning (DDSRL) framework with a deep architecture for this issue. In DDSRL, the first-layer dictionary atoms are automatically learned from raw signals and borrowed for sparse coding to enhance sparsity and interclass discriminability. Then, the weight matrix is defined to screen high-energy atoms from the upper dictionary as new training samples for the next dictionary learning and sparse coding layers, thereby eliminating interclass redundant atoms and mining deeper discriminative representations of cyclostationary impulses or meshing harmonics from the shallow dictionary. Finally, DDSRL extracts feature sequences sensitive to fault-induced waveforms via the learned dictionaries and coding coefficients for intelligent fault identification. Experimental verifications on two datasets with high-speed bearing and compound gear-bearing faults demonstrate that DDSRL outperforms six popular sparse classification models, sparse autoencoder, convolutional neural network, and principal component analysis network. Furthermore, the layer-by-layer feature extraction process of DDSRL and feature visualization analysis provide more credible fault diagnosis results.