Embedded Mechanical Reflectors for Haptic Plate Mode Control
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Solution Overview
Problem
Existing haptic interface technologies face challenges in maintaining desired vibration modes on non-rectangular surfaces with defects such as rounded corners or material heterogeneities, leading to wave propagation disturbances and energy loss.
Innovation Solution
The use of recessed mechanical reflectors, which are strategically positioned to define an active zone on the surface, excluding defects and optimizing the placement of piezoelectric actuators to maintain desired Lamb wave modes, such as antisymmetric Lamb modes, by simulating and sizing the reflectors using finite element methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric actuators are used to generate Lamb waves on a plate surface, then haptic feedback is achieved through the squeeze film effect, but wave propagation is disrupted when the plate has non-rectangular geometry or defects
Solution Approach 1:
The plate surface is segmented into a defect-free active zone and defect areas by introducing mechanical reflectors. The reflectors create discrete boundaries that confine Lamb wave propagation to specific regions, allowing the wave generation and propagation to occur only in areas free of geometric defects or material heterogeneities.
Solution Approach 2:
The harmful defect areas are extracted from the active propagation zone by positioning mechanical reflectors at strategic locations. This isolates defects such as rounded corners, holes, or material heterogeneities from the Lamb wave path, effectively removing their disruptive influence from the haptic feedback mechanism.
2Reliability
If mechanical reflectors are introduced to define an active zone, then wave propagation is improved by excluding defects, but device complexity increases
Solution Approach 1:
The mechanical reflectors are merged with the plate structure itself, using the plate's own material and geometry to create the reflective boundaries. This integration approach minimizes additional components while achieving the desired wave confinement effect.
Solution Approach 2:
The mechanical reflectors act as intermediary elements between the defect areas and the active zone. These reflectors mediate the wave propagation by reflecting waves away from defect regions while allowing controlled propagation in the active zone, thus protecting the haptic feedback mechanism from defect-induced disruptions.
3Reliability
If the active zone is reduced to exclude defects, then wave propagation uniformity is improved, but the area available for haptic interaction is reduced
Solution Approach 1:
The mechanical reflectors are positioned to dynamically optimize the active zone size based on the Lamb wave characteristics and defect locations. By adjusting the reflector positions and dimensions, the active zone is maximized while maintaining uniform wave propagation and excluding defect areas.
Solution Approach 2:
The dimensions and positioning parameters of the mechanical reflectors are optimized to achieve the maximum possible active zone area while maintaining uniform Lamb wave propagation. By carefully controlling the reflector geometry and location, the balance between active zone size and propagation uniformity is achieved.
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
This approach effectively compensates for defects, ensuring adequate plate mode propagation and maintaining the desired vibration mode with improved amplitude and uniformity, even on non-rectangular plates with rounded corners or material defects, by isolating defects from the active zone and optimizing actuator placement.
Implementation Method 1
a piezoelectric element installed in the diaphragm to vibrate the diaphragm
Implementation Method 2
using piezoelectric thin films as actuators... a piezoelectric material such as PZT (lead zirconate titanate), which enables the activation of a plate mode such as the propagation mode of antisymmetric Lamb waves
Implementation Method 3
This vibration mode induces an air gap, known as the 'squeeze film' effect, between the finger and the plate, which causes a change in the coefficient of friction between the plate and the finger
Implementation Method 4
at least one embedded mechanical reflector (3) for ensuring adequate propagation of the plate mode on the surface of a support... said embedded mechanical reflector being configured to block said plate mode at a blocking position
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3~4
AI summary
The invention concerns a vibrating device comprising: - a first support (1) configured to be deformable having a surface (S) defined in a plane along directions X and Y; - at least one actuator (2) configured to generate plate modes propagating in said first support; - said first support comprising: o at least one defect with respect to the propagation of the plate modes; o said defect being of a geometric nature or corresponding to a structural heterogeneity; characterised in that it comprises: - a second support (4); - at least one embedded mechanical reflector (3) rigidly connected to said first support and in contact with said first support, configured to block said first support in at least one direction Z perpendicular to said directions X and Y, said mechanical reflector being rigidly connected to said second support and; - said embedded mechanical reflector being configured to isolate a so-called active area (Sa) belonging to said surface (S) defined in a plane along directions X and Y in which the plate modes propagate, said active area excluding said defect; - said actuator being located in said active region.