A New Myohaptic Instrument to Assess Wrist Motion Dynamically

Sensors 2010, 10, 3180-3194; doi:10.3390/s100403180

Mario Manto 1, Niels Van Den Braber 2, Giuliana Grimaldi 3 and Piet Lammertse 2
1  FNRS, Neurologie ULB-Erasme, 808 Route de Lennik, 1070 Bruxelles, Belgium
2  Moog FCS, 2150 Ad Nieuw-Vennep, The Netherlands;
3  Neurologie, ULB Erasme, 808 Route de Lennik, 1070 Bruxelles, Belgium;


OPEN ACCES
Abstract: The pathophysiological assessment of joint properties and voluntary motion in neurological patients remains a challenge. This is typically the case in cerebellar patients, who exhibit dysmetric movements due to the dysfunction of cerebellar circuitry. Several tools have been developed, but so far most of these tools have remained confined to laboratories, with a lack of standardization. We report on a new device which combines the use of electromyographic (EMG) sensors with haptic technology for the dynamic investigation of wrist properties. The instrument is composed of a drivetrain, a haptic controller and a signal acquisition unit. Angular accuracy is 0.00611 rad, nominal torque is 6 N·m, maximal rotation velocity is 34.907 rad/sec, with a range of motion of –1.0472 to +1.0472 rad. The inertia of the motor and handgrip is 0.004 kg·m2. This is the first standardized myohaptic instrument allowing the dynamic characterization of wrist properties, including under the condition of artificial damping. We show that cerebellar patients are unable to adapt EMG activities when faced with an increase in damping while performing fast reversal movements. The instrument allows the extraction of an electrophysiological signature of a cerebellar deficit.

Keywords: movement; sensor; myohaptic; damping; ataxia

FULL TEXT PDF