Pin-hole Tactile Sensor for Robot Arm Size Reduction
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Solution Overview
Problem
Existing tactile sensors for robot arms are oversized due to the use of cameras, which increases the device size and can suffer from stray light noise, reducing detection sensitivity.
Innovation Solution
A tactile sensor unit utilizing a pin-hole layer, optical sensor, light sources, deformation layer, and marker, where the pin-holes shorten the optical path length and the light sources are positioned to prevent direct light entry, thereby reducing size and stray light, and a robot arm unit incorporating these sensors for downsizing and improved sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera is used to measure surface displacement of the robot arm distal end, then detection capability is achieved, but the device size increases by an amount corresponding to the focal length of the camera
Solution Approach 1:
The patent extracts the lens from the optical system and replaces it with a pinhole array, eliminating the need for focal length space while maintaining imaging capability. This removes the bulky lens component and its associated mounting space, directly resolving the size issue while preserving surface displacement detection functionality
Solution Approach 2:
The pinhole array serves as an intermediary optical element that performs the function of a lens without requiring the same physical space. The pinholes create multiple projection paths that converge on the sensor, achieving image formation without a traditional lens focal point, thus enabling compact sensor design
2Illumination intensity
If reflection light from a light source is used for camera measurement, then illumination is provided, but stray light becomes noise that reduces detection sensitivity
Solution Approach 1:
The patent applies local quality by positioning light sources at specific locations that correspond to through-holes in the pinhole layer, creating localized illumination zones. This ensures that light is provided only where needed for specific pinhole projections, preventing stray light from entering other pinholes and maintaining high detection sensitivity while providing sufficient illumination
Solution Approach 2:
The illumination system is segmented into multiple independent light sources, each corresponding to a specific through-hole and pinhole pair. This segmentation allows precise control of light paths, enabling illumination for individual measurement zones without creating stray light interference in other zones, thus maintaining overall detection sensitivity
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 achieves downsizing of the tactile sensor unit and suppresses stray light, allowing for enhanced detection sensitivity and a wider detection region with increased depth of field and dynamic range.
Implementation Method 1
The tactile sensor unit and the robot arm unit each use a plurality of pin-holes. This allows an optical path length to be shortened and also allows a depth of field to be increased as compared with a case of using a lens.
Implementation Method 2
in a case where reflection light of light from a light source is used at the time of measurement by the camera
Implementation Method 3
The deformation layer is disposed at a position on a side opposite to the plurality of light sources in a positional relationship with respect to the pin-hole layer. The marker is disposed on a surface of the deformation layer or inside of the deformation layer.
Data Source
AI summary
A tactile sensor unit according to one embodiment of the present disclosure includes a pin-hole layer, an optical sensor, a plurality of light sources, a deformation layer, and a marker. The pin-hole layer has a plurality of pin-holes and a plurality of first through holes. The optical sensor is disposed at a position opposed to the plurality of pin-holes via a predetermined gap. The plurality of light sources is disposed in a layer between the pin-hole layer and the optical sensor, at locations respectively opposed to the plurality of through holes. The deformation layer is disposed at a position on a side opposite to the plurality of light sources in a positional relationship with respect to the pin-hole layer. The marker is disposed on a surface of the deformation layer or inside of the deformation layer.