Development of a Shoulder Disarticulation Prosthesis System Intuitively Controlled With the Trunk Surface Electromyogram

Abstract

We developed an intuitively operational shoulder disarticulation prosthesis system that can be used without long-term training. The developed system consisted of four degrees of freedom joints, as well as a user adapting control system based on a machine learning technique and surface electromyogram (EMG) of the trunk. We measured the surface EMG of the trunk of healthy subjects at multiple points and analyzed through principal component analysis to identify the proper EMG measurement portion of the trunk, which was determined to be distributed in the chest and back. Additionally, evaluation experiments demonstrated the capability of four healthy subjects to grasp and move objects in the horizontal as well as the vertical directions, using our developed system controlled via the EMG of the chest and back. Moreover, we also quantitatively confirmed the ability of a bilateral shoulder disarticulation amputee to complete the evaluation experiment similar to healthy subjects.

Semi-Automated Control System for Reaching Movements in EMG Shoulder Disarticulation Prosthesis Based on Mixed Reality Device

“…1 shows an overview of the proposed control system for the EMG-SD prosthesis. As a control target, we used a simple EMG-SD prosthesis developed by our research group [6] . HoloLens (Microsoft, USA) was used as the MR device to measure the visual information of the external environment.…”

“…The signal processing method of the motion operational EMG is the same as that of the conventional system [6] . The motion operational EMGs were measured by the main-microcomputer with a sampling frequency of 2000 Hz, filtered using a second-order Butterworth high-pass filter with a cutoff frequency of 50 Hz.…”

“…Because a body-powered shoulder disarticulation prosthesis requires alternative physical movements of the user, an electric shoulder disarticulation prosthesis driven by actuators is an area of focus [1] . Among them, an electromyographic shoulder disarticulation (EMG-SD) prosthesis, which uses the user's myoelectricity as a control input, can be operated intuitively using biological signals [2] – [6] . Compared with an EMG prosthesis for forearm amputees, an EMG-SD prosthesis has many movable body parts, that is, many degrees of freedom (DoFs) in terms of control.…”

“…Our research group developed a simple EMG-SD prosthesis that can manipulate a two-degree-of-freedom (2-DoF) robotic arm and a 2-DoF robotic hand using only surface EMG and pattern recognition techniques [6] . We demonstrated that the developed simple EMG-SD prosthesis can grasp and move an object in three-dimensional (3D) space without long-term training by utilizing the user's body movements.…”

“…Similarly, the control of the EMG-SD prosthesis will be separated from the slow visual feedback control loop of the user by detecting the motor condition and planning the motion through visual information obtained by the control system itself. In our conventional system [6] , the user always relies on his/her own visual information to recognize the object to be grasped, the state of the robotic arm, and the motion of the robotic arm being performed. Therefore, when the user performs the reaching movement with the conventional EMG-SD prosthesis system, he/she must always visually check whether the robotic hand has reached the object.…”