Haptic Device Shear Force Generation via Lateral Oscillation

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Solution Overview

Problem

Existing haptic devices can only vary forces resisting finger motion and cannot redirect finger motion, lacking the ability to provide shear forces, which limits their haptic feedback capabilities.

Innovation Solution

A haptic device that subjects a substrate to lateral motion or oscillation in synchrony with friction-reducing ultrasonic oscillations, allowing for the creation of shear forces on a user's finger or object, using a combination of piezoelectric bending elements and linear actuators controlled by a computer system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If only friction modulation is used, then the device structure is simple, but the haptic feedback capability is limited to resistive forces only

Engineering Contradiction:
Improvehaptic feedback capabilityVSAvoiddevice structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines friction modulation capability with lateral motion capability into a single haptic device. The substrate can both modulate surface friction through ultrasonic vibrations and generate lateral motion through piezoelectric actuators, merging two functions into one integrated system that provides both resistive and propulsive haptic feedback.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The haptic device is designed to perform multiple functions: it can provide resistive forces through friction modulation and propulsive forces through lateral motion, making it a multi-functional haptic interface that can guide finger exploration and provide diverse tactile feedback beyond what single-function devices can achieve.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Ease of operation

If only resistive forces are provided, then the control system is simple, but the ability to redirect finger motion is lost

Engineering Contradiction:
Improvefinger motion guidanceVSAvoidcontrol system
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The device transitions from static friction modulation to dynamic lateral motion generation. By using piezoelectric actuators to create controlled lateral movements of the substrate, the system dynamically guides finger exploration rather than merely resisting motion, enabling active propulsion and redirection of user interaction.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent replaces passive mechanical friction resistance with active piezoelectric actuation. Instead of relying solely on friction forces to control finger motion, the system uses piezoelectric elements to generate controlled lateral movements that actively guide and redirect finger exploration in desired directions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables guiding forces for finger exploration and object manipulation, enhancing haptic experiences by providing both variable friction and shear forces, suitable for applications in robotic and manufacturing contexts.

Implementation Method 1

one or more piezoelectric bending elements for subjecting the substrate to lateral oscillation

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

one or more ultrasonic vibration elements for subjecting the substrate to friction reducing ultrasonic oscillation

Methodology Applied
Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Data Source

PatentEP2491476B1Haptic device with controlled traction forces
Publication Date: 2019.12.11 NORTHWESTERN UNIV
  • EP2491476B1 patent drawingFigure 1A~2
  • EP2491476B1 patent drawingFigure 3
  • EP2491476B1 patent drawingFigure 3A~6B

AI summary

A haptic device includes a substrate that is subjected to lateral motion such as lateral oscillation with one or more degees of freedom together with modulation of a friction reducing oscillation in a manner that can create a shear force on the user's finger or on an object on the device.