Viscoelastic Pressure Sensor Slip Detection via Stress Dispersion
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Solution Overview
Problem
Existing tactile sensors for robot hands struggle to accurately detect slip between the gripped object and fingers, particularly in stable gripping and skillful manipulation, as they often rely on stick slip oscillation or fail to measure slip direction effectively.
Innovation Solution
A detecting device with a pressure sensor having a multilayer structure, utilizing viscoelastic material that calculates the pressure center position and movement to detect slip based on stress dispersion, allowing for precise detection of shearing force and slip direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor measures shape or dynamic characteristic of a pressed object (elasticity and viscoelasticity), then the sensor can detect material properties, but the sensor cannot measure a sense of slip
Solution Approach 1:
The patent combines a pressure-sensitive element and a piezoelectric element into a single tactile sensor device. The pressure-sensitive element detects vertical pressure while the piezoelectric element detects shearing force through stick-slip oscillation, merging multiple detection functions into one integrated sensor that can measure both material properties and slip information simultaneously
Solution Approach 2:
The tactile sensor is designed to perform multiple functions: detecting contact presence, measuring vertical pressure, detecting shearing force, and measuring slip through stick-slip oscillation. This multi-functional sensor replaces the need for separate sensors for each measurement type, enabling comprehensive object interaction detection
2Measurement precision
If a sensor detects oscillation due to stick slip, then the sensor can detect slip occurrence, but it is difficult to detect a direction of the slip
Solution Approach 1:
The pressure-sensitive element is divided into multiple detection points arranged in a matrix pattern. By analyzing the distribution and movement of pressure across these segmented detection points, the sensor can calculate the direction of slip in addition to detecting slip occurrence, overcoming the limitation of single-direction detection
Solution Approach 2:
The patent transitions from detecting only the magnitude of stick-slip oscillation to analyzing the two-dimensional pressure distribution across multiple detection points. This dimensional expansion enables the calculation of slip direction by examining pressure changes across different spatial coordinates
3Measurement precision
If a sensor obtains a sense of slip based on stick slip oscillation due to friction, then the sensor can detect slip, but the sensor requires complex waveform analysis
Solution Approach 1:
The patent replaces complex waveform analysis of piezoelectric signals with a simpler method that directly correlates pressure distribution changes across detection points with slip direction. This substitution reduces computational complexity while maintaining accurate slip detection capabilities
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
Enables more accurate acquisition of slip information necessary for stable gripping and manipulation by robot hands, improving control and preventing object slippage through real-time detection of slip and direction.
Implementation Method 1
a pressure sensor having a multilayer structure, utilizing viscoelastic material that calculates the pressure center position and movement to detect slip based on stress dispersion
Implementation Method 2
calculating the pressure center position and movement to detect slip based on stress dispersion
Data Source
AI summary
A detecting device including a pressure sensor that is deformed by a load from an outside and causes stress dispersion includes a slip detecting unit that calculates a pressure center position using a pressure value detected by the pressure sensor, calculates a movement value of the calculated pressure center position using a temporal change of the pressure center position, and detects a slip on the basis of the calculated movement value of the pressure center position. The pressure sensor has a multilayer structure in which two detecting units that detect pressure are arranged to hold a viscoelastic body made of a viscoelastic material that is deformed by a load from the outside.