EFFECT OF A PNEUMATICALLY DRIVEN HAPTIC INTERFACE ON THE PERCEPTIONALCAPABILITIES OF HUMAN OPERATORS

This paper describes experimental studies conducted using a pneumatica lly driven haptic interface (PHI) system. The PHI is a unilateral exos keletal device that tracks the motion of the shoulder and elbow. The s tudy was carried out to evaluate the impact of an exoskeletal haptic i nterface on human perceptional capabilities. A population of twenty su bjects participated in a set of experiments that were tailored to asse ss force sensation, shape perception, and effect of force feedback in task performance. Using Weber fractions, we contrasted the outcome of our force sensation experiments against results reported by psychophys ical researchers. The results indicated that the perception of weight (or force magnitude) through the haptic interface was significantly af fected for relatively low reference force levels (4.44 N, Weber fracti on = 0.5). The effect progressively diminished as the force level was increased, and almost matched the natural human capabilities for a ref erence force level of 18 N (Weber fraction = 0.06). The haptic shape i dentification experiments showed that the subjects were able to identi fy various shapes using the PHI system (1 = 0.3 m reference length, wi th Weber fraction = 0.38). This identification, however, was adversely affected by the lack of tactile sensation in the haptic device. The o utcome of the force-feedback experiments demonstrated mixed results, a n observation that was consistent with experimental studies of other r esearchers. While force feedback did not affect the time needed to com plete the task, the subjects' performance was significantly improved w hen the experiments involved controlling the thickness of a curve draw n on a pressure-sensitive tablet.