Tactile Interface Inverse Filtering for Vibration Localization
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Solution Overview
Problem
Existing tactile stimulation interfaces struggle to provide localized feedback on rigid surfaces, such as trackpads, due to vibration propagation and cross-talk between actuators, leading to unwanted stimulation of non-target fingers.
Innovation Solution
A tactile stimulation interface that uses a surface with at least one actuator capable of generating vibrations, along with inverse filtering to control the actuators and compensate for vibration propagation, ensuring localized stimulation by canceling vibrations in non-target areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid plate surface is used for tactile interface, then the surface durability and smoothness are improved, but vibration propagation causes cross-talk between actuators leading to loss of stimulation localization
Solution Approach 1:
The system applies preliminary anti-action by calculating and applying counter-vibrations through inverse filtering before the harmful vibration propagation can affect non-target areas. The control system pre-computes compensation signals that cancel out the expected cross-talk vibrations, allowing rigid surfaces to be used while maintaining localization precision.
Solution Approach 2:
The system implements feedback by measuring the actual vibration propagation characteristics of the rigid surface and using this information to adjust the actuator control signals. The inverse filter is trained on the specific surface properties and continuously compensates for vibration leakage, enabling precise localized stimulation despite the rigid surface's natural tendency to propagate vibrations.
2Productivity
If multiple actuators are activated simultaneously to stimulate multiple fingers, then the productivity of tactile feedback is improved, but vibration cross-talk increases causing pollution in non-target areas
Solution Approach 1:
The system uses feedback through inverse filtering to dynamically adjust each actuator's control signal based on the combined vibration effects of all active actuators. The control system continuously compensates for cross-talk between simultaneously activated actuators, enabling multi-finger stimulation without vibration pollution in non-target areas.
Solution Approach 2:
The system replaces pure mechanical isolation approaches with a control-theory-based solution. Instead of physically isolating actuators through mechanical means, the system uses inverse filtering and active vibration control to achieve the same effect, allowing closer actuator spacing and more flexible multi-finger stimulation configurations.
3Manufacturing precision
If high-frequency vibrations are used for localized tactile feedback, then the precision of stimulation localization is improved, but audible noise is generated reducing natural sensation
Solution Approach 1:
The system applies parameter changes by dynamically adjusting the frequency content of vibration signals based on the desired localization precision and noise constraints. The inverse filter enables effective localization at lower frequencies by compensating for vibration propagation, allowing the system to operate in the 0-1 kHz range for natural sensation while maintaining precision through active control rather than relying on high-frequency content.
4Manufacturing precision
If vibration-absorbing surfaces are used to isolate actuators, then the stimulation localization is improved, but the device volume increases making it incompatible with mobile devices
Solution Approach 1:
The system replaces bulky mechanical vibration-absorbing surfaces with a compact control-theory-based inverse filtering system. This substitution eliminates the need for large volumes of damping material while achieving the same localization effect through electronic control and active vibration compensation, making the technology suitable for mobile devices with strict space constraints.
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 interface achieves independent movement and stimulation in desired areas, eliminating cross-talk and providing accurate, localized tactile feedback, even on rigid surfaces, while maintaining a compact design.
Implementation Method 1
at least one actuator intended to generate a vibration at an area of the surface where it is desired to generate a tactile stimulation
Implementation Method 2
means for calculating control signals implementing an inverse filtering operation... The inverse filtering makes it possible to compensate for the propagation effects
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4D
AI summary
A touch interface including a plate (1) bearing an interaction surface (2) for interaction with one or more external elements, including a plurality of interaction zones (Z1, Z2, Z3, Z4) positioned with respect to one another such that they cover substantially the entire interaction surface (2), and a plurality of actuators (A1, A2, A3, A4) in contact with the plate, control means (6) for controlling the actuators, configured so as to send control signals to the actuators, comprising calculating means (8) for calculating said control signals, said calculating means (8) implementing an inverse filtering operation, so as to transmit, on the basis of one or more desired movements of one or more interaction zones (Z1, Z2, Z3, Z4), control signals that at least partially compensate wave propagation, reverberation and distortion.