Tool wear condition monitoring during the machining process is one of the most important considerations in precision manufacturing. Cutting force is one of the signals that has been widely used for tool wear condition monitoring, which contains the dynamical information of tool wear conditions. This paper proposes a novel multivariate cutting force-based tool wear monitoring method using one-dimensional convolutional neural network (1D CNN). Firstly, multivariate variational mode decomposition (MVMD) is used to process the multivariate cutting force signals. The multivariate band-limited intrinsic mode functions (BLIMFs) are obtained, which contain a large number of nonlinear and nonstationary tool wear characteristics. Afterwards, the proposed modified multiscale permutation entropy (MMPE) is used to measure the complexity of multivariate BLIMFs. The entropy values on multiple scales are calculated as condition indicators in tool wear condition monitoring. Finally, the one-dimensional feature vectors are constructed and employed as the input of 1D CNN to achieve accurate and stable tool wear condition monitoring. The results of the research in this paper demonstrate that the proposed approach has broad prospects in tool wear condition monitoring.

The complex background pattern of color-patterned fabrics, the small target of some defects, the difficulty separating them from the background, and the extreme aspect ratio present challenges for their automated, real-time detection. To solve the above problems, the YOLOv5s-based color-patterned fabric defect detection algorithm was proposed by combining lightweight modules. For the small target defects of color-patterned fabrics, coordinate attention was introduced in the feature extraction part to guide the model to focus entirely on the target defect area and suppress the background noise of color-patterned fabrics. Meanwhile, the bidirectional feature pyramid network was introduced in the feature fusion part to give different fusion weights to the extracted feature maps, improve the efficiency of feature fusion, and guide the model further to distinguish the fabric defects from the color-patterned background. Finally, the k-means algorithm was used to generate anchor boxes for the extreme aspect ratio of fabric defects to improve the training efficiency and accuracy of the model. Self-built datasets were experimented with to verify the improved model’s detection effect. The results show that the improved YOLOv5s model can reach 87.7% and 0.881 in mean average precision and F1 score, which are 2.3% and 0.02 better than the original model, respectively. The detection speed of the improved YOLOv5s model reached 60.24 frames per second (GPU 1660). After deployment on the fabric defect detection platform, the speed of detecting color-patterned fabrics can reach 15 m/min.

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Tool wear significantly affects the interface condition between the machining tool and the workpiece, causing nonlinear vibrations that negatively impact machining quality. The vibration on the axes of X, Y and Z are both generated during machining process, and multivariate vibration signals collected by triaxial accelerometers contain dynamical information of tool wear accurately and comprehensively. This paper proposes a novel in-situ tool wear monitoring approach using multivariate signal processing and intrinsic multiscale entropy analysis. Multivariate variational mode decomposition (MVMD) is firstly used to process multivariate vibration signals. The multivariate band-limited intrinsic mode functions (BLIMFs) contain nonlinear and nonstationary wear characteristics of multivariate vibration signals. Afterwards, the refined composite multiscale dispersion entropy (RCMDE) is employed to measure the complexity and regularity of multivariate BLIMFs quantitatively. Finally, the feature matrices composed of entropy values on multiple scale of multivariate BLIMFs are adopted as the input of CNN to achieve accurate tool wear monitoring. The results show the proposed approach is promising for tool wear monitoring.