Method for Evaluating the Force Controllability of Human Finger

The ability of human finger in controlling force against impact load is determined by means of a novel practical method, a variation of the levitation mass method. In the method, a mass that is levitated with a pneumatic linear bearing, and hence encounters negligible friction, is made to collide with an object under test. During the collision the Doppler frequency shift of a laser beam reflecting from the mass is accurately measured using an optical interferometer. The velocity, position, acceleration and inertial force of the mass are calculated from the measured time-varying Doppler shift. The method is characterized by the facts that the preparation for the test is easy and the measurement accuracy is high. The importance of the visual information is also determined by means of conducting the tests under the condition of either the subject´s eyes opened or closed