Extraction of Voluntary Muscle Contraction Based on PCA Reconstruction Error with a Reference of Skin Deformation at Passive Movement

Extraction of voluntary muscle contraction is important in assessing motor function in patients with severe upper-limb impairments. In this study, we proposed an extraction method of voluntary muscle contraction based on reconstruction error of principle component analysis (PCA), referencing skin deformation at passive movement. Skin deformations of the upper arm were collected on nine conditions of elbow joint movement, including passive, voluntary isotonic, and voluntary isometric. Experimental results indicate that the reconstruction error using the first principle component extracts muscle contraction at the level of 20% of maximum voluntary force (MVF) or more.