Piezoelectric Brake Sensor Electrode Layout for Cross-Talk Control
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Solution Overview
Problem
Piezoelectric shear force sensors integrated into braking devices experience unreliable and non-repeatable measurements due to 'cross talk' when subjected to both shear and normal forces, particularly in reported electrode sensors, which are sensitive to these combined forces.
Innovation Solution
A shear force sensor design with a piezoelectric material having orthogonal flat faces and a second electrode configuration symmetrically extended from one face, collecting signals while minimizing cross talk by aligning electrodes symmetrically with the central axis of the material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If reported electrode sensors are used for shear force detection, then industrial manufacturing ease is improved, but measurement reliability deteriorates due to cross talk when subjected to combined normal and shear forces
Solution Approach 1:
The patent applies asymmetry by positioning the second electrode asymmetrically relative to the first electrode on the piezoelectric material surface. Specifically, the second electrode is placed at a distance from the first electrode along a first direction parallel to the polarisation axis, breaking the symmetry that causes cross-talk. This asymmetric configuration allows the sensor to distinguish between shear force signals and normal force interference, thereby improving measurement reliability while maintaining ease of manufacture through a relatively simple electrode layout modification
2Measurement precision
If electrodes are positioned to collect shear force signals, then shear force detection capability is improved, but sensitivity to normal force interference worsens
Solution Approach 1:
The patent applies local quality by creating a specific local electrode configuration where the second electrode is positioned at a controlled distance from the first electrode along a direction parallel to the polarisation axis. This local structural differentiation modifies the electric field distribution in the region between and around the electrodes, enabling selective sensitivity to shear forces while reducing response to normal forces. The local quality change in electrode arrangement thus improves shear force detection precision without excessive sensitivity to normal force interference
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 sensor provides reliable and repeatable measurements of shear forces even under simultaneous normal and shear force conditions, suitable for industrial applications.
Implementation Method 1
Piezoelectricity is the property of certain materials to polarise, generating a build-up of electrical charge, and thus a potential difference, when mechanically stressed.
Implementation Method 2
the opposite effect can occur, i.e. generating a deformation in the material by subjecting it to an electrical voltage, in which case we speak of an inverse piezoelectric effect.
Implementation Method 3
The application of an external electric field causes a rearrangement of the material's dipoles, which align parallel to its direction, making the total electric dipole no longer zero, as a result of which the material becomes polarised.
Data Source
AI summary
Braking device for a vehicle, with a piezoelectric sensor (2) comprising: a piezoelectric material, two electrodes (6, 7), wherein the piezoelectric material comprises a first flat face (4) and a second flat face (5), the faces extending in parallel planes identified by two orthogonal y and z directions, wherein an electrical signal is collected by the electrodes when the piezoelectric material is simultaneously subjected to a normal force in an x-direction and to a shear force in the z-direction, wherein the first electrode is positioned on the first face and the second electrode is positioned on the second face and has extensions (7a, 7b) on the first face separated by the first electrode, wherein each of said extensions extends on a corresponding side of said first face, and wherein each of said extensions is symmetrically configured with respect to a central axis of the first face.