Improving repeatability of surface electromyography measurement of sit-to-stand motions by using muscle synergy

This study proposes a method to improve the measurement stability of sit-to-stand (STS) motion, one of the most important motions for human mobility. STS motion is complex and uses numerous muscles ranging from the feet to the torso. Electromyography (EMG) is often used to analyze STS motion by precisely measuring the activity of the contributing muscles. However, such measurements depend strongly on the measurement conditions, such as electrode attachment conditions, and variations in the contributing muscles and initial poses. We examined the variability caused by these conditions and explored a method to stabilize STS measurements by EMG. The proposed method adjusts measurements using data aggregation and muscle synergy computation, which leads to better comparisons or integration of motion measurements with two or more motion strategies or motions acquired over multiple EMG electrode reinstallations. The experimental results show that the proposed method improves the similarity of measurements under different conditions.