Robot Wrist Force Sensor Calibration for Unknown Tool Mass
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Solution Overview
Problem
Existing robot control systems struggle to accurately determine the mass and center-of-gravity position of tools with unknown properties using force sensors, especially when the tool's mass and position change due to grasping or ambient temperature fluctuations.
Innovation Solution
A robot control device that includes a measurement-value acquisition unit, storage unit, and correction unit to correct force sensor measurements by comparing known and unknown tool states, using specific motions and temperature compensation to calculate the tool's mass and center-of-gravity position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force sensor measurements are used to determine tool mass and center-of-gravity position, then robot control accuracy is improved, but measurement precision deteriorates when tool mass is unknown or changes due to grasping
Solution Approach 1:
The system performs preliminary calibration by acquiring force sensor measurements when tools with known mass and center-of-gravity position are disposed at the wrist. This preliminary data collection enables the creation of a reference dataset that is stored and later used to correct measurements when unknown tools are used, resolving the contradiction between measurement precision and adaptability to unknown tools.
Solution Approach 2:
The correction unit uses feedback from the stored measurement data to continuously improve the accuracy of tool parameter determination. By comparing force sensor measurements with the pre-acquired reference data, the system generates corrected values that compensate for unknown tool properties and temperature variations, thereby maintaining high measurement precision across different tool conditions.
2Adaptability or versatility
If correction algorithms are implemented to handle unknown tools, then adaptability is improved, but device complexity increases
Solution Approach 1:
The robot control device integrates multiple functions into a unified system: the measurement-value acquisition unit serves both calibration and operational measurement purposes, the storage unit maintains reference data for various tool conditions, and the correction unit applies universal correction algorithms that work across different tool types and temperature conditions. This multi-functionality reduces overall system complexity while maintaining high adaptability.
Data Source
AI summary
A robot control device controls a robot equipped with a sensor capable of measuring force, the robot control device including: a measurement value acquisition unit acquires a first measurement value measured by the sensor when a first tool having a known mass and center-of-gravity position is placed at the tip of the wrist of the robot and the wrist performs a specific motion, and a second measurement value measured by the sensor when a second tool having a known mass and center-of-gravity position is placed and the wrist performs a specific motion; a measurement value storage unit that stores the first measurement value and the second measurement value acquired by the measurement value acquisition unit; and a correction unit that corrects the measurement values from the sensor, on the basis of the first measurement value and the second measurement value stored in the measurement value storage unit.