Manual control in space--research on perceptual-motor functions under zero gravity condition

Microgravity effects on human factor were studied through a series of manual control experiments conducted in the First Material Processing Test. The Japanese Payload Specialist operated a finger stick for 130 seconds to maintain a light spot movement around the center of a vertical LED array display. The stick angle is doubly integrated to make the controlled element motion. The light spot position indicates the difference between the motion and pseudo-random wave patterns which drives the man-machine tracking system. 24 runs were conducted in each of 2 months before launch, immediately pre-flight, and post-flight experiments. During the flight experiments, the PS felt pain in fast eye movement. He was obliged to fix his line of sight at the center of display and to watch the displayed error movement using peripheral view. He also felt difficulty in supporting his body against reaction force of his hand movement. During a few days after landing, disturbance was observed in the PS's posture. The operator describing function analysis revealed the disappearance of the "regression" phenomenon and increment of the effective time delay. As the result, the flight describing function showed better fit to the simplified model of lead with pure time delay.