Efficient Facial Expression Recognition With Representation Reinforcement Network and Transfer Self-Training for Human–Machine Interaction

The emotion perception capability could endow machines with deeper feedback evaluation of human–machine interaction (HMI), which makes the experience of HMI more harmonious and natural. Currently, how to obtain the robust surface and semantic facial representation features has not been fully explored, moreover, the parameters and computation of conventional convolutional neural network models, which are adopted in facial expression recognition (FER) are too heavy, it is not conducive to the deployment of the HMI system. Therefore, this article proposes a representation reinforcement network (RRN) and transfer self-training (TST) based efficient FER method. Our designed RRN is mainly composed of two modules, i.e., surface representation reinforcement (SurRR) module and semantic representation reinforcement (SemaRR) module. SurRR module fuses the facial features in different dimensions and highlights key feature messaging nodes in feature maps. SemaRR module establishes the deep semantic representation of global facial regions on spatial and channel dimensions. Therefore, RRN has stronger feature extraction capability when the parameters and computational complexity are significantly reduced, and TST is proposed for contributing to the training effect of RRN at the condition of insufficient training data. We tested our method on the extended Cohn-Kanade dataset (CK+), Radboud faces database (RaFD), FERPLUS, and the real-world affective faces database (RAF-DB) datasets, and the recognition accuracy are 100%, 98.62%, 89.64%, and 88.72%, respectively. Furthermore, the preliminary application experiment, which demonstrates the feasibility of our method in practice during HMI.