Conference 5–9 August 2012
Exhibition 7–9 August 2012
Los Angeles Convention Center

Ungrounded Haptic Rendering Device for Torque Simulation in Virtual Tennis

Los Angeles Convention Center, Concourse Foyer

This haptic device that looks and handles like a real tennis racket is capable of rendering a variety of strong forces and twisting torques experienced in real tennis.

Impact forces are common in real life, and our daily experience shows that our sensory systsem can discern the variations in these vibrations. Common vibration-motor-based haptics cannot create the force magnitude, or the variations in frequencies and waveforms, or the immediacy of such impacts. This prototype device overcomes the above deficiencies to enhance the user experience.

The primary innovation is the A-shaped vibration element. One lightweight high-power push-pull solenoid actuator is mounted to each slanted side of the A. Part of the handle of the racket houses that vibration element, while the rim is mounted to the horizontal beam of the A. In this way, the racket is divided into two flexibly coupled moving masses. The low-mass rim has a large moment of inertia and acts as an effective counterweight to generate torque. Peak torque is generated within 10ms while the prototype is freely swung in the air, without being attached to the ground or large masses. The actuator on each slanted side of the A can render large accelerations of varying frequencies and waveforms. Actuating both sides in phase simulates a direct hit on the racket's center, while out-of-phase actuation simulates the torques experienced in off-center impacts. The device generates up to 0.4Nm of torque for simulating ball impacts, and 0.2Nm about the long axis of the handle to simulate twisting in the player's grip. Tracking of the user's head allows for projective mapping during graphics rendering, so that the 3D trajectory of the ball can be perceived, and adds visual cues to improve the haptic effect.

Wee Teck Fong
Institute for Infocomm Research

Ching Ling Chin
Institute for Infocomm Research

Farzam Farbiz
Institute for Infocomm Research

Zhiyong Huang
Institute for Infocomm Research