“…Machine learning is an extremely important tool that is widely applied in biomedical engineering (Dindo et al, 2017;Mcfarland and Wolpaw, 2017;Ofner et al, 2017;Pereira et al, 2017;Bockbrader et al, 2018). For studying action intention understanding, good classification accuracy is one of the most critical factors (Dindo et al, 2017;Ofner et al, 2017;Bockbrader et al, 2018). In recent years, many researchers have performed numerous experiments with machine learning, but most of the classification results are unsatisfactory (Zhang et al, 2015(Zhang et al, , 2017Liu et al, 2017;Pereira et al, 2017).…”