A STUDY OF HAND GRIP PRESSURE DISTRIBUTION AND EMG OF FINGER FLEXOR MUSCLES UNDER DYNAMIC LOADS

A matrix of miniature and flexible pressure sensors is proposed to mea sure the grip pressure distribution (GPD) at the hand-handle interface of a vibrating handle. The GPD was acquired under static and dynamic loads for various levels of grip forces and magnitudes of vibration at different discrete frequencies in the 20-1000 Hz range. The EMG of fi nger flexor muscles was acquired using the silver-silver chloride surf ace electrodes under different static and dynamic loads. The measured data was analysed to study the influence of grip force, and magnitude and frequency characteristics of handle vibration on: (i) the local co ncentration of forces at the hand-handle interface; and (ii) the elect rical activity of the finger flexor muscles. The results of the study revealed high interface pressure near the tips of index and middle fin gers, and base of the thumb under static grip conditions. This concent ration of high pressure shifted towards the middle of the fingers unde r dynamic loads, irrespective of the grip force, excitation frequency, and acceleration levels. The electrical activity of the finger flexor muscles increased considerably with the grip force under static as we ll as dynamic loads. The electrical activity under dynamic loads was o bserved to be 1.5-6.0 times higher than that under the static loads.