Surface electromyography (sEMG) of the sternocleidomastoid (SCM) muscle for variable control using head movement technology

We have explored the feasibility of an alternative strategy using biological signals such as sEMG of the sternocleidomastoid muscle (SCM) for variable control of our head movement system. Seven volunteers were instrumented with bilateral sEMG sensors on the SCM. Basic neck movements of lateral tilts and graded head rotations were performed. Data were normalized as a percentage of maximum voluntary contractions (MVC) for right and left sides, respectively. The contribution from ipsilateral sEMG signal as percentage of full-range was ∼75% for left and 55% for right head tilts. During head rotations at 30, 45, and 60° to both sides, results for sEMG signal amplitude as a percentage of MVC showed excellent reproducibility of the contralateral SCM at approximately 10%, 18%, and 32% on both sides. Despite the small number of subjects for a thorough statistical analysis, no differences exist in t-tests between sEMG (as % of MVC) right and left sides during head rotation; however, differences do exist for each level of rotation (p<0.01). Head rotation provided the most consistent sEMG signal correlation with the degree of motion in all subjects, allowing for reproducible proportional control for our head movement technology.