This paper proposes a new method for real-time rigid body simulations for haptic interfaces based on contact volume. Analytical methods for calculations of contact forces take too much time to keep fast update rates of haptic controls. In addition, they prohibit direct connection of haptic interfaces.Penalty methods, which employ spring-damper model for calculations of contact force, are very fast per iterations. In addition, they permit direct connection of haptic interfaces. Therefore penalty methods are good for haptic interactions.However, previous penalty methods do not regard distribution of contact forces over contact area. They can't calculate normal and friction forces on face-face contacts correctly. We suppose distributed spring-damper model on contact area to solve these problems. We analyze three dimensional shape of intersection part on polyhedral objects. Then, we integrate forces and torques of distributed spring-damper models. We implement proposed simulator and compare it with point-based penalty method. It showed that only proposed simulator can simulate face-face contact and friction forces correctly. In addition, we connect a 6 DOF haptic interface to the simulator. Users can feel 6 DOF force feedback and input 6 DOF motion.

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A successful catch of a falling ball requires an accurate estimation of the timing for when the ball hits the hand. In a previous experiment in which participants performed ball-catching task in virtual reality environment, we accidentally found that the weight of a falling ball was perceived differently when the timing of ball load force to the hand was shifted from the timing expected from visual information. Although it is well known that spatial information of an object, such as size, can easily deceive our perception of its heaviness, the relationship between temporal information and perceived heaviness is still not clear. In this study, we investigated the effect of temporal factors on weight perception. We conducted ball-catching experiments in a virtual environment where the timing of load force exertion was shifted away from the visual contact timing (i.e., time when the ball hit the hand in the display). We found that the ball was perceived heavier when force was applied earlier than visual contact and lighter when force was applied after visual contact. We also conducted additional experiments in which participants were conditioned to one of two constant time offsets prior to testing weight perception. After performing ball-catching trials with 60 ms advanced or delayed load force exertion, participants’ subjective judgment on the simultaneity of visual contact and force exertion changed, reflecting a shift in perception of time offset. In addition, timing of catching motion initiation relative to visual contact changed, reflecting a shift in estimation of force timing. We also found that participants began to perceive the ball as lighter after conditioning to 60 ms advanced offset and heavier after the 60 ms delayed offset. These results suggest that perceived heaviness depends not on the actual time offset between force exertion and visual contact but on the subjectively perceived time offset between them and/or estimation error in force timing.