Framework for human haptic perception with delayed force feedback

Time delays in haptic teleoperation affect the ability of human operators to assess mechanical properties (damping, mass, and stiffness) of the remote environment. To address this, we propose a unified framework for human haptic perception of the mechanical properties of environments with delayed force feedback. In a first experiment, we found that the delay in the force feedback led our subjects to underestimate all the three mechanical properties. Moreover, subjects perceived additional damping or stiffness properties that the environment did not possess. It was found that the extents of these changes in the perception depend on both time-delay magnitude and the frequency of the movement with which subjects interacted with the environment. This was due to the fact that subjects were not able to distinguish the delay-caused phase shift in the movement-force relation from changes in the three mechanical properties. Based on this, we proposed a framework that allowed for a prediction of the change associated with delayed force in perception of mass-spring-damper environments. The framework was corroborated by a second experiment, in which a combined mass-damper environment was tested. Our hypotheses that the delay would cause subjects to underestimate the mass but overestimate the damping and that the extents of the under- A nd overestimation would differ between individual subjects due to the difference in the interaction frequency were confirmed.