Robot Hand Force Sensing With Calculated Moment Detection
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Solution Overview
Problem
Industrial robot hands face challenges with large, complex force detection sensors that increase finger size, lead to wiring issues, and require complicated calibration, making them unreliable and prone to interference during assembly operations.
Innovation Solution
A robot hand design with three-axis force detection sensors and moment calculation capabilities, using load cells, strain gauges, or optical deformation measurement systems, which allows for accurate force measurement and moment calculation without the need for six-axis sensors, simplifying the structure and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If six-axis force detection sensors are incorporated near the fingers of a robot hand, then measurement precision of reaction force is improved, but device complexity and finger size increase
Solution Approach 1:
The force detection function is segmented into two parts: simple three-axis force sensors are installed in the fingers, while the complex moment calculation is performed separately by the control device using detected forces and finger position information. This segmentation reduces sensor complexity while maintaining six-axis measurement capability.
Solution Approach 2:
The control device acts as an intermediary that receives simple three-axis force data from sensors and computes the equivalent six-axis force and moment information. This intermediary processing eliminates the need for complex six-axis sensors in the fingers while achieving the same measurement objective.
2Measurement precision
If six-axis force detection sensors are incorporated near the fingers of a robot hand, then measurement precision of reaction force is improved, but the robot hand interferes with workpiece during assembly
Solution Approach 1:
The measurement function is segmented between simple sensors in the fingers and computational processing in the control device. This allows using smaller, simpler sensors that do not interfere with workpiece assembly while maintaining accurate six-axis measurement capability through software calculation.
3Measurement precision
If force detection sensors are incorporated in the fingers, then measurement precision is improved, but wiring disconnection and contact failure occur
Solution Approach 1:
The complex wiring and calibration requirements are extracted from the finger-mounted sensors and relocated to the control device. The simplified three-axis sensors in fingers have fewer wiring connections, reducing the risk of disconnection and contact failure while maintaining measurement capability through centralized processing.
4Measurement precision
If six-axis force detection sensors are used, then measurement precision is improved, but calibration becomes complicated
Solution Approach 1:
The calibration process is segmented into two stages: simple calibration of three-axis force sensors in the fingers, followed by computational calibration of the moment calculation algorithm in the control device. This segmentation makes calibration more manageable compared to calibrating complex six-axis sensors as a single unit.
Solution Approach 2:
The control device serves as an intermediary that handles the complex calibration computations. Instead of calibrating complex six-axis sensors directly in the fingers, the system uses simple three-axis sensor calibration combined with computational moment calculation, simplifying the overall calibration process.
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
This design enables accurate assembly control by calculating forces and moments in three-axis directions, reducing the size and weight of the robot hand, enhancing reliability, and minimizing interference with workpieces during assembly.
Implementation Method 1
force detection sensor that detects forces in three axis directions acting on the gripping fingers
Implementation Method 2
a moment calculation unit that calculates moment forces about three axes based on the detected forces and positional information about the gripping fingers
Data Source
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AI summary
Force sensors capable of measuring only forces in xyz coordinate axis directions are installed in fingertips, respectively, and forces and moment forces acting on a robot hand are calculated based on positional information about each fingertip. This structure eliminates the need for using large force sensors to thereby enable downsizing of each fingertip, and enables detection of loads and moment forces acting on the robot hand.