Using Audio Recordings to Characterise a Soft Haptic Joystick

Abstract

The principle of particle jamming, a physical effect where fluids can be made to change their hardness at will, has many applications in engineering. Previous research has investigated combining this change of hardness with other haptic effects, resulting in a technology that can render vibration, hardness/softness and shape. This paper proceeds to describe the application of this technology to a soft haptic joystick handle for use in interactive games and telerobotics scenarios. Dynamically generated sound waveforms are used to drive vibrations inside the handle, and a microphone records these as they reach the tip of the handle under different jamming conditions. Audio frequency analysis is then used to analyse the behaviour of the resulting vibrations. This analysis shows that vibration is lowest under a strong vacuum, confirming previous observations that increasing the hardness of the particle fluid has the effect of restricting the displacement of the source vibrations. Moreover, frequency of vibration remained broadly stable in both hard and soft states again confirming previous observations. These results, obtained with a fundamentally different haptic device and sound-based instrumentation, necessitate the conclusion that the behaviour of particle jamming controlled vibration is repeatable and controllable regardless of the physical configuration in which it is used.