Directional Force Sensation by Asymmetric Oscillation From a Double-Layer Slider-Crank Mechanism

By subjecting a small object in a handheld device to periodic translational motion with asymmetric acceleration (accelerated more rapidly in one direction than in the other), the holder typically experiences the kinesthetic illusion of being pushed or pulled continuously by the held device. We have been investigating the effect because of its potential application to a handheld, nongrounded, haptic device that can convey a sense of a continuous translational force in one direction. A one-degree-of-freedom haptic device based on a double-layer slider-crank mechanism was constructed based on the results of our previous research. Our results with the new haptic device show that (i) humans perceive directed force sensation by asymmetric oscillation, (ii) 5 counts/s is the best frequency to generate the force sensation, (iii) the ratio of the gross weight of the device and the weight of the reciprocating mass should be at least 16% for effective force perception, and (iv) the force perception is the same with the device held in either hand.