A human-factors evaluation of switch actuators for use in spacecraft

The characteristics of switch actuators for communications equipment to be used in spacecraft are investigated. Subjects operated common switch actuators with space-suit gloves, under both atmospheric pressure and two-psi pressure differential. The independent variables studied were type of actuator, direction of operation, actuating torque, number of switch positions, effect of pressure, practice effect, and position on the panel. The dependent variables (criteria) were operating time, errors, and ranks. Switch actuators, in general, were operated more slowly and with more errors under simulated spacecraft conditions than under ordinary conditions. It was found that multiposition switches must have firm detent or interlocking features to prevent overshoot or accidental reversal. The best switch actuator under all circumstances combined is shown in Fig. 1.