The Effect of Damping on the Perception of Hardness

Abstract

In teleoperation systems, damping is often injected to guarantee system stability during contact with hard objects. In this study, we used psychophysical experiments to assess the effect of adding damping on the user’s perception of object hardness. In Experiments 1 and 2, combinations of stiffness and damping were tested to assess their effect on perceived hardness. In both experiments, two tasks were used: an in-contact task, starting at the object’s surface, and a contact-transition task, including a free-air movement. In Experiment 3, the difference between global damping (present throughout the environment) and local damping (present inside the object only) was tested. In all experiments, force and position data were recorded to assess which parameters correlated with the participant’s perceptual decision. Experiments 1 and 2 show that with added damping, perceived hardness increased for an in-contact task, while it decreased for a contact-transition task, with the latter effect being much larger than the former. Experiment 3 shows that this effect was mainly due to the addition of global damping, since there was a large perceptual difference between adding global and local damping. The force and position parameters show that object indentation, mean velocity and adjusted rate-hardness correlated most strongly with the participant’s perceptual experience.