8-channel monopolar sEMG signals were acquired using the device developed by our research group at a sampling rate of 1000 Hz. Medical gel electrodes (CH50B, Shanghai Hanjie Electronic Technology Co., LTD., Shanghai, China) were used for data collection. The position of the electrodes is shown in Fig. 2. The REF electrode was placed on the inner side of the upper big arm near the elbow and the RLD electrode was placed on the outer side of the right upper arm near the elbow. Eight monopolar electrodes were placed on the right forearm.