Motion quality evaluation of upper limb target-reaching movements.

Fitts' Law was extended in the polar coordinate system, and a set of indices for human motion evaluation is proposed. In this paper, the index of difficulty and the index of performance are introduced as the general indices for the quality measure of plane target-to-target movement. As an example, the target-reaching movement of the upper limb, which is a basic functional action of upper limbs in the activities of daily living, was experimentally investigated. Five healthy subjects were asked to perform six target-reaching tasks with different indices of difficulty. All movements were recorded using a Vicon motion analysis system. The movement quality was measured using these evaluation indices.