## 1 Introduction  
Surface electromyography (sEMG) has been well recognized as an effective tool to generate control commands for devices and human-assisting manipulators (such as exoskeletons and prostheses). In human-computer interaction controls, the most important feature of bioelectrical signals is that they can directly reflect the user's intentions and muscle activities. The interactive device must be adapted to the articulation and consistent with the operator's movement. In recent years, the sEMG proportional control method has been gradually developed on the basis of pattern recognition. This method requires that the joint motion angle is continuously recognized, and the quality of the human-computer interaction is largely limited by the accuracy of recognition [1]. In previous studies, many scholars have discussed classification algorithms and tried various methods to improve the control accuracy of sEMG [2]. However, there are some interrelated factors that can have an important impact on the control process because of differences in tasks or operators. These factors are rarely noticed by people, such as the direction of movement, concentration of attention or proprioception. Most daily autonomous movements depend on a continuous monitoring of muscle contraction based on proprioceptive and exteroceptive sensory feedback [3]. This feedback allows continuous readjustments and corrections of muscle contraction according to the purpose of the action, and is transmitted to the central nervous system to ensure the precise position of the limb. First of all, vision is an important channel to feel the outside, and motion control has obvious visual reliance. Vision can guide the attention of the individual. Therefore, the study of visual feedback can focus on an analysis of the effects of motion control from an external and internal focus of attention. In addition,assigning a certain level of attention or ontological attention can increase the stability of motion [4]. Some studies have shown that the focus of attention has an important impact on action execution [5]. Internal focus of attention focuses on one's action itself, and external focus of attention pays attention to the efficiency of action. [PERSON] et al. [6] demonstrated for the first time that the sEMG activity was different under internal and external focus of attention conditions, and their study showed that surface electromyographic activity decreased when subjects used an external focus of attention. It also showed that changes in attention may make interactive control more natural and more efficient in motion mode. In addition, proprioception represents some neurosensory receptors, which do not have visual feedback, including limb location and motor sensation, power sensation, and balance sensation [7]. [PERSON] and [PERSON] [8] used closed eye tests to show that the effects of proprioception and visual feedback are different in the stability of human motion. Therefore, the influence of proprioception is an important factor that needs to be tested, in order to reduce the fluctuation of muscle force, maintain the stability of exercise and improve the accuracy of sEMG control of upper limbs. In previous studies, most authors have discussed how attention and proprioception maintain posture [9] or enhance motor skills learning [10]. These studies focused on the outcome of motion, and their methods were mostly to discuss the characteristics of muscles during sustained isometric contraction. Few scholars have studied the motion process, and have not discussed how to improve the efficiency of human-computer interactions and the accuracy of continuous proportional control by selecting these factors. In continuous motion control, since the mode of action between muscles changes momentarily, it is necessary to ensure the coordination and stability of muscles throughout a motion.