Evanescent Wave Haptic Feedback via Strip Plate Design
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Solution Overview
Problem
Existing touch interfaces with vibrotactile feedback struggle to provide localized feedback, especially for multitouch or multiuser interactions, due to uniform vibration distribution and complex signal processing requirements.
Innovation Solution
A haptic interface with an elongate-shaped interaction surface supported at its edges, using actuators and a control module to generate control signals at frequencies below the cutoff frequency of the first propagation mode, creating evanescent waves for localized vibrotactile feedback, allowing for multitouch and multiuser capabilities with simplified signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional actuators are used to generate vibrations through the surface, then vibrotactile feedback is transmitted to the user, but the vibration energy is uniformly distributed over the entire surface, making it impossible to provide localized feedback
Solution Approach 1:
The interaction surface is divided into multiple independent strips, each capable of being vibrated independently by its own actuator. This segmentation allows localized vibrotactile feedback to be generated at specific positions without affecting other areas of the surface.
Solution Approach 2:
Each strip is equipped with its own actuator to provide locally tailored vibrotactile feedback. The support structure is designed to mechanically isolate adjacent strips, ensuring that vibrations generated in one strip do not propagate to neighboring strips, thereby achieving local quality control.
2Measurement precision
If time reversal or inverse filtering techniques are used to shape the vibration field and create localized vibrations, then high-quality localized vibrotactile feedback is achieved, but the signal processing becomes complex
Solution Approach 1:
The patent extracts and eliminates the need for complex signal processing techniques such as time reversal or inverse filtering. Instead, localization is achieved through the physical design of the support structure and the use of evanescent waves, which naturally confine vibrations to local areas without requiring sophisticated control algorithms.
Solution Approach 2:
The support structure is designed to automatically confine vibrations to specific strips through its mechanical properties. The evanescent waves generated by the actuators naturally decay within each strip without requiring external control or processing, allowing the system to self-localize vibrations.
3Device complexity
If the entire contact area is subjected to the same vibration, then simple actuator control is used, but it is not possible to generate variations at a scale smaller than the size of the fingers for static fingers
Solution Approach 1:
The interaction surface is segmented into multiple narrow strips, each controlled by its own actuator. This segmentation enables spatial resolution at a scale smaller than the size of fingers, allowing distinct vibrotactile feedback to be provided to different fingers or to different locations on the same finger.
Solution Approach 2:
Each strip acts as a flexible mechanical element that can be independently vibrated. The thin-film-like structure of the strips allows them to respond to actuator vibrations while maintaining mechanical isolation from adjacent strips, enabling fine spatial resolution.
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
The solution enables effective localized vibrotactile feedback and multitouch/multiuser interactions with reduced energy distribution across the entire surface, enhancing user experience and interaction precision while simplifying signal processing compared to prior art.
Implementation Method 1
The control module is configured to generate control signals to the actuator at frequencies lower than the cutoff frequency of the first propagation mode of the plate, so that the actuator generates evanescent waves in the plate
Data Source
AI summary
The invention relates to a haptic interface comprising a substrate (2), a plate (4) comprising a surface (6) for interaction with one or more fingers of a user, and actuators (A1) capable of applying a vibration to said plate (4), and a control module (MC) for controlling said actuator,—said plate (4) being in the shape of a strip extending along a first direction (X) and delimited transversely to the first direction by two lateral edges (10), said lateral edges (10) being supported by said substrate (6),—said control module (MC) being configured to generate control signals to said actuator (A1) at first frequencies lower than the cut-off frequency of the first propagation mode of said plate, so that the actuator (A1) generates evanescent waves in the plate (4).