Abstract
Hands-and-knees crawling, an effective rehabilitation method for children with motor impairments, requires precise phase detection for optimizing assistive devices. However, research on phase detection in human crawling remains limited. The research explores whether multijoint kinematic synergy (KS) features provide better accuracy than traditional time-domain (TD) features. Nine healthy adults participated in the study, where accelerometers and pressure sensors were used to capture motion and pressure data during crawling. The data were preprocessed and used to define four distinct phases of crawling, and kinematic synergy features were extracted using singular value decomposition-based principal component analysis (PCA). Machine learning models, including classification and regression trees (CART), K-nearest neighbors (KNN), and error-correcting output codes support vector machines (ECOC-SVM), were trained to recognize the crawling phases. Their performance was compared to that of traditional time-domain features. The phase recognition method based on multijoint kinematic synergies achieved an average accuracy of 89.37%. Specifically, the accuracy for CART was 88.41%, for KNN was 85.51%, and for ECOC-SVM was 94.20%. In comparison, the phase recognition using traditional time-domain features yielded lower accuracy, with overall accuracies of 75.36% for CART, 76.09% for KNN, and 85.51% for ECOC-SVM. The findings demonstrate that using multijoint kinematic synergy features significantly improves the accuracy of crawling phase recognition compared to traditional time-domain features. These recognized phases can be used to interpret the user's intent, which can then be integrated into exoskeleton control systems. In particular, high-level control systems can detect this intent and communicate it to lower-level systems, enabling precise motion commands. This integration holds promise for improving rehabilitation outcomes, especially for patients with conditions like cerebral palsy.