EMG-based Hybrid Impedance-Force Control for Human-Robot Collaboration on Ultrasound Imaging

Ultrasound (US) imaging is a common but physically demanding task in the medical field, and sonographers may need to put in considerable physical effort for producing high-quality US images. During physical human-robot interaction on US imaging, robot compliance is a critical feature that can ensure human user safety while automatic force regulation ability can help to improve task performance. However, higher robot compliance may mean lower force regulation accuracy, and vice versa. Especially, the contact/non-contact status transition can largely affect the control system stability. In this paper, a novel electromyography (EMG)-based hybrid impedance-force control system is developed for US imaging task. The proposed control system incorporates the robot compliance and force regulation ability via a hybrid controller while the EMG channel enables the user to online modulate the trade-off between the two features as necessary. Two experiments are conducted to examine the hybrid controller and show the necessity of involving an EMG-based modulator. A proof-of-concept study on US imaging is performed with implementing the proposed EMG-based control system, and the effectiveness is demonstrated. The proposed control system is promising to ensure robot's stability and patient's safety, thus obtain high-quality US images, while monitoring and reducing sonographer's fatigue. Furthermore, it can be easily adapted to other physically demanding tasks in the field of medicine.