Tactile Sensor Light Guide Diffusing Marker Force Detection
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Solution Overview
Problem
Tactile sensors face inaccuracies in detecting external forces due to changes in light emission quantity or illumination characteristics, particularly when the light path from the emission unit to the receiving unit is deformed.
Innovation Solution
A tactile sensor design featuring a light emission unit, a light guide unit with diffusing markers and opening portions, and a light-receiving unit, where the light is projected to different positions on the receiving surface, allowing for accurate force detection regardless of light emission changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light source is used to detect external force through light quantity change, then the sensor can detect force magnitude, but the detection accuracy deteriorates due to light emission quantity variations and illumination characteristic changes
Solution Approach 1:
The patent uses a marker that creates a light reflection pattern as a copy of the light source behavior. Instead of directly measuring absolute light quantity from the source, the system measures the reflected light pattern from the marker, which copies the light source characteristics but encodes positional information. This copying approach allows the system to ignore light emission variations and focus on positional changes for accurate force detection.
Solution Approach 2:
The patent utilizes changes in light reflection characteristics (analogous to color changes) of the marker based on its position. As the marker moves due to applied force, the reflected light pattern changes position and intensity distribution on the sensor array. This optical property change provides a reliable measurement signal that is independent of the light source emission quantity variations.
2Measurement precision
If the light path is made deformable to sense external force, then the sensor can detect force application, but the illumination characteristic changes cause detection inaccuracy
Solution Approach 1:
The marker reflects light to create a pattern that copies the light source characteristics while encoding positional information. The system measures this reflected pattern rather than the direct light path, thereby eliminating the problem of illumination characteristic changes in the light path affecting measurement accuracy.
Solution Approach 2:
The patent replaces direct mechanical measurement of light path deformation with an optical measurement of marker reflection pattern. Instead of measuring physical displacement or strain in the light path, the system uses light reflection from the marker to indirectly measure position, substituting a mechanical measurement approach with an optical one that is more accurate and less sensitive to illumination variations.
3Measurement precision
If a lens is added to focus light for better detection, then the spatial resolution improves, but the device thickness increases
Solution Approach 1:
The patent replaces the mechanical optical system (lens) with a direct optical detection approach. The marker's reflection pattern is projected directly onto the sensor array without requiring focal length, eliminating the need for thick lens structures while maintaining spatial resolution through the distributed sensor elements.
Solution Approach 2:
The patent transitions from one-dimensional point detection to two-dimensional pattern detection. By using an array of light-receiving elements that capture the spatial distribution of reflected light from the marker, the system achieves high spatial resolution without needing optical focusing elements, effectively using dimensional expansion to replace mechanical optical components.
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 highly accurate force detection, resistant to variations in light emission and illumination characteristics, with a lensless configuration that reduces thickness and improves sensitivity and spatial resolution.
Implementation Method 1
including a marker configured to diffuse light, incident via the one surface, toward the light guide unit
Data Source
AI summary
A tactile sensor includes a light guide unit extending in a predetermined direction, provided to guide light, incident from a light-emitting element, in the predetermined direction and including a pair of surfaces opposite to each other extending in the predetermined direction, an optical translucent elastic member, disposed on one side of the light guide unit, including a marker configured to diffuse light incident via one surface of the light guide unit toward the light guide unit, a light-receiving unit provided on the other side of the light guide unit and including a plurality of light-receiving elements on a light-receiving surface, and a plurality of opening portions provided between the light guide unit and the light-receiving unit and optically opened such that the light from the marker is projected to different positions, spaced apart from one another, on the light-receiving surface of the light-receiving unit.