Knee Joint Assist Method Focusing on Joint Viscosity Properties Using IMU - Based Exoskeleton Assist Device

Exoskeleton-type assistive device is worn directly on the person, so it is important to improve coordination. In previous studies, the authors focused on the viscosity characteristics of human joints, proposed a knee joint assist method with a wide tolerance range for misalignment between the human and the device, and confirmed the effectiveness of the method. However, in previous studies, assist torque was output based on device information, which affected the misalignment between the device and the wearer. Therefore, this study examines the assist effectiveness of a viscosity assist method using inertial measurement units (IMU s) that can be directly attached to a person. In the first experiment, we compared measurements taken by an encoder mounted on the knee joint of the device and by IMU directly attached to the person during a squatting motion, and compared the misalignment of the measurements depending on the presence or absence of a command torque to the device. As a result, we confirmed the effectiveness of the IMU in reducing the misalignment between the measurement values of the device and the wearer. In the second experiment, we proposed knee joint viscosity assist method based on IMU angular velocity data during seated movement, and verified the assist effect of the proposed method and the method proposed in the previous study by measuring surface electromyography potentials. As a result, the effectiveness of the proposed method was confirmed.