The Implications of Surface Stiffness for Size Identification and Perceived Surface Hardness in Haptic Interfaces

This paper presents a two-part study of the effects of virtual surface stiffness on haptic perception. First, size identification experiments were performed to determine the effects of system quality, in terms of surface stiffness, on the ability of a human to identify square cross-section ridges by size in a simulated environment. Then, discrimination experiments were performed to determine relationships between virtual surface stiffness and simulation quality in terms of perceived surface hardness. Results of experiments to test human haptic perception for varying virtual surface stiffnesses indicate that haptic interface hardware may be able to convey sufficient perceptual information to the user at relatively low levels of virtual surface stiffness. Subjects, however, can perceive improvements in perceived simulated surface hardness as stiffness levels are increased in the range of achievable parameters for this hardware. The authors draw several conclusions about allowable time delays in a haptic interface system based on the results of the surface stiffness experiments. This paper can be treated as a second part to [1], which presented similar experiments and results for two other machine parameters, maximum force output and system bandwidth.