Extraction of the envelope from surface EMG signals

Electrical signals recorded by means of surface electromyography (SEMG) contain some useful information for a better understanding of strategies underlying human movement. In particular, a great contribution to biomechanic studies may be provided by a correct estimation of the amplitude of SEMG signals that is related to the force exerted by muscles. This information could, in fact, represent an indirect assessment of muscular force obtained without using invasive measurement techniques. This article presents a new fully automatic estimation technique adaptively working on SEMG signal characteristics. The discussion of the theoretical background of the estimator together with a feasibility study demonstrates the usefulness of its application. An example of the application to signals recorded during dynamic protocols is also shown.