Arm Motions in the Horizontal Plane

Abstract

The principles of motion economy, “Motions of the arms should be made in opposite and symmetrical directions, and should be made simultaneously”, and, “Eye fixations should be as few and as close together as possible”, are evaluated. The two principles are replaced with five principles: 1. For one-hand motions, movements which pivot about the elbow are preferred to movements which pivot about the shoulder. 2. For one-hand motions, movements with the preferred hand are more desirable than movements with the non-preferred hand. 3. Two-hand motions are preferred to one-hand motions. 4. For two-hand motions, simultaneous motions are preferred to alternating motions. 5. For two-hand simultaneous motions, a pattern which minimizes eye fixations is preferred.