An Unsupervised Regularization and Dropout based Deep Neural Network and Its Application for Thermal Error Prediction

• Published in: Applied sciences 2020-04, Vol.10 (8), p.2870
• Main Authors: Tian, Yang, Pan, Guangyuan
• Format: Article
• Language: English
• Subjects: Algorithms; Coadaptation; Error analysis; Error compensation; foundation; heavy duty machine tool; Machine tools; Model accuracy; Neural networks; Neurons; Prediction models; Regularization; self-organizing deep belief network; Sensors; Space temperature; Temperature gradients; Temperature sensors; thermal error; Transfer functions
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app10082870

Due to the large size of the heavy duty machine tool-foundation systems, space temperature difference is high related to thermal error, which affects to system’s accuracy greatly. The recent highly focused deep learning technology could be an alternative in thermal error prediction. In this paper, a thermal prediction model based on a self-organizing deep neural network (DNN) is developed to facilitate accurate-based training for thermal error modeling of heavy-duty machine tool-foundation systems. The proposed model is improved in two ways. Firstly, a dropout self-organizing mechanism for unsupervised training is developed to prevent co-adaptation of the feature detectors. In addition, a regularization enhanced transfer function is proposed to further reduce the less important weights of the process and improve the network feature extraction capability and generalization ability. Furthermore, temperature sensors are used to acquire temperature data from the heavy-duty machine tool and concrete foundation. In this way, sample data of thermal error predictive model are repeatedly collected from the same locations at different times. Finally, accuracy of the thermal error prediction model was validated by thermal error experiments, thus laying the foundation for subsequent studies on thermal error compensation.