An extending Fitts´ Law for human upper limb performance evaluation

Human motor behavior is complex and is challenging to understand. Fitts´ Law presented a relationship between speed, accuracy, amplitude of movement and target size in upper extremity tasks. In this paper, Fitts´ Law was extended from one-dimensional motion to two-dimensional motion in the polar coordinate system for the human upper limb performance. Based on this, a set of indices were proposed. The index of difficulty and the index of performance were introduced as the general indices for the quality measure of plane pointing movement, which is a basic functional action of upper-limb in human daily life. Five healthy subjects were asked to perform six pointing tasks with different indices of difficulty. All movements were recorded using a Vicon motion analysis system. The movement quality was evaluated using these evaluation indices.