Capacitive Detection Surface for Combined Contact and Pressure Sensing
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Solution Overview
Problem
Current capacitive object detection systems in robotics require separate and interfering sensors for approach/contact and pressure detection, making them costly, cumbersome, and inefficient.
Innovation Solution
A single sensor device utilizing electrode-object capacitance for approach/contact detection and electrode-guard capacitance for pressure detection, with electrical polarization methods generating alternating potentials and potential differences to distinguish between signals, allowing simultaneous measurement of both without mutual interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate sensors are used for approach/contact detection and pressure detection, then detection functionality is achieved, but device complexity and cost increase
Solution Approach 1:
The patent combines approach/contact detection and pressure detection into a single capacitive sensor system. By using one sensor with multiple measurement modes rather than separate sensors, the device complexity is reduced while maintaining full detection functionality. The single sensor measures both the capacitance between electrode and object (for approach/contact) and capacitance between electrode and guard electrode (for pressure).
Solution Approach 2:
The capacitive sensor is designed to perform multiple functions: detecting object approach, object contact, and pressure force. A single sensor structure with electrode and guard electrode configurations enables it to measure different physical quantities (capacitance variations) to provide comprehensive detection capabilities that would otherwise require multiple specialized sensors.
2Reliability
If separate sensors are used for approach/contact detection and pressure detection, then detection coverage is complete, but manufacturing cost increases
Solution Approach 1:
The patent merges the functionality of multiple sensors into a single capacitive sensor assembly. This reduces the bill of materials, simplifies manufacturing processes, and lowers assembly costs while maintaining complete detection coverage for approach, contact, and pressure measurements.
3Reliability
If multiple sensors are juxtaposed in detection surface, then detection capabilities are comprehensive, but mutual interference degrades sensor performance
Solution Approach 1:
The patent segments the measurement process into distinct capacitive measurement modes within a single sensor. By measuring electrode-object capacitance for approach/contact and electrode-guard electrode capacitance for pressure, the system separates different detection functions electronically rather than using physically separate sensors, eliminating mutual interference while maintaining comprehensive detection capabilities.
Solution Approach 2:
The guard electrode acts as an intermediary structure that enables pressure measurement without interfering with approach/contact detection. By measuring capacitance between the electrode and guard electrode, the system obtains pressure information while the guard electrode shields against parasitic effects, improving measurement precision.
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 cost-effective, less complex, and more efficient detection of object approach/contact and pressure, improving performance by eliminating sensor interference and simplifying implementation.
Implementation Method 1
a first value representative of a first piece of information relating to an approach and/or a contact of the object with the detection surface, namely a value of an electrode-object capacitance, and a second value representative of a second piece of information relating to a support, a pressure and/or a force exerted by the object on the detection surface, namely a value of an electrode-guard capacitance
Data Source
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AI summary
The invention relates to a device (100) for detecting an object (102) in relation to a detection surface (104), comprising at least one measuring electrode (106) and at least one guard electrode (108) separated via a distance (D) which is elastically locally modifiable by a pressure exerted by said object (102) on said detection surface (104); and means for the electrical polarisation of the electrodes (V, E) arranged so as to (i) apply the same first alternating electrical voltage (Vg) to the measuring electrodes and guard electrodes (106, 108) in order to measure a first signal in relation to an object-electrode capacitance (Ceo); and to (ii) apply an alternating electrical voltage (V1) difference between the measuring electrodes and the guard electrodes (106, 108) in order to measure a second electrical signal in relation to a guard-electrode (Ceg) capacitance. The invention also relates to a detection method using such a detection device.