Measuring responses to precision requirements

The paper reports two pilot studies aimed at obtaining information on the muscular response to precision requirements. Two experimental designs to measure the end point stiffness of the hand in manual work have been investigated from a methodological point of view. Surface EMG was used to monitor the activity in selected superficial muscles of the shoulder under different demands of precision. Contrary to expectations, the results indicate that, as requirements of precision are increased, EMG levels are unaffected or lowered. Correspondingly, the frequency content of hand motion is generally lowered, although the acceleration levels increase.