Enhancing Variable Friction Tactile Display Using an Ultrasonic Travelling Wave

Area of Science:

• Haptics
• Human-Computer Interaction
• Tribology

Background:

• Variable friction tactile displays utilize ultrasonic standing waves to reduce friction.
• Existing methods are limited by saturation and require finger movement, necessitating high vibration amplitudes for low friction.

Purpose of the Study:

• To develop a novel tactile display system using a travelling wave instead of a standing wave.
• To extend the modulation range of tangential force, including zero and negative values.
• To investigate the psycho-physical perception of the travelling wave effect.

Main Methods:

• Implementation of a robust control system for generating a travelling wave on planar surfaces.
• Experimental analysis of the forces generated by the travelling wave.
• Psycho-physical studies to evaluate user perception of the tactile feedback.

Main Results:

• The travelling wave system extends the modulation range of tangential force to zero and negative values.
• The generated force comprises two contributions: friction reduction and a driving force opposing the wave.
• The tactile effect is dependent on the direction of finger movement relative to the travelling wave.

Conclusions:

• Travelling wave technology offers enhanced control over friction in tactile displays compared to standing waves.
• The ability to achieve negative friction opens new possibilities for realistic tactile feedback.
• Direction-dependent tactile perception is a key characteristic of this new system.