Human Factors for Designing a Haptic Interface for Interaction with a Virtual Environment

Designing haptic displays is one of the main challenges in creating virtual reality systems with the sense of touch. The design of the hardware and software of haptic interfaces depends critically on the capabilities of the human haptic system. For example, force feedback interfaces, due to inherent hardware limitations such as friction and actuator saturation, present forces to users in the case of interactions with a virtual environment which are only approximations of the forces that they would feel if they were interacting with the real world. Thus, quantitative human studies are required to obtain the impact on human performance of these approximations in the forces from the haptic devices. First, the focus of this paper is on the quantitative measures of human factors (force thresholds) that affect the design specifications of force feedback haptic interfaces when the human user or the object are in relative motion. Second, the effects of two direction of forces and the increment/decrement of forces are also studied through two experiments. It appears that the JNDs of human force perception depend on the force direction and the force increment/decrement, and these two variables must be incorporated in an efficient haptic design technique when the user´s hand is in motion.