Industrial Robot Force Sensor Self-Calibration for Drift Correction
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Solution Overview
Problem
Industrial robot force sensors experience drift over time, necessitating regular correction of measured force values to prevent malfunction and undesired movements, which existing systems fail to address effectively.
Innovation Solution
A method for automatically calibrating industrial robot force sensors by calculating a correction coefficient based on joint positions and external force measurements, using a self-calibration module to update the coefficient incrementally under specific conditions, ensuring accurate force control without interrupting robot operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force sensor correction is applied regularly to maintain measurement accuracy, then measurement precision is improved, but device complexity increases due to the need for continuous calibration procedures
Solution Approach 1:
The force sensor calibration system performs self-calibration automatically using the robot's own motion data and force measurements. The calibration algorithm processes the robot joint positions and measured forces to compute correction coefficients without requiring external calibration equipment or manual intervention, enabling the system to service itself continuously during operation.
Solution Approach 2:
The system dynamically adjusts the correction coefficient parameters based on real-time measurements of robot joint positions and applied forces. By continuously updating these parameters through calculated correction coefficients, the system adapts to sensor drift and maintains measurement accuracy without requiring physical re-calibration or system reconfiguration.
2Reliability
If automatic calibration is implemented to maintain force measurement accuracy, then reliability is improved, but computational load increases requiring more processing power
Solution Approach 1:
The calibration algorithm processes only the necessary subset of data required for correction coefficient calculation, using selected robot joint positions and force measurements rather than analyzing all available sensor data. This partial processing approach maintains calibration effectiveness while reducing unnecessary computational overhead and energy consumption.
Solution Approach 2:
The system performs preliminary calculations of robot mass effects and gravitational forces before computing the final correction coefficients. By pre-processing these known physical effects, the calibration algorithm can focus computational resources on determining the sensor drift corrections rather than recalculating all physical parameters from scratch during each calibration cycle.
3Measurement precision
If continuous calibration updates are performed to compensate for sensor drift, then measurement precision is maintained, but response time decreases due to processing requirements
Solution Approach 1:
The calibration process operates continuously during robot operation rather than requiring periodic interruptions or separate calibration phases. The algorithm continuously processes incoming force measurements and joint position data to update correction coefficients in real-time, ensuring uninterrupted calibration action that maintains measurement precision without halting robot operations.
Solution Approach 2:
The calibration updates are performed at regular measurement cycles during robot operation, applying correction coefficients periodically based on accumulated measurement data. This periodic updating approach balances the need for continuous precision with computational processing requirements, updating corrections at optimal intervals rather than attempting instantaneous continuous adjustment.
Data Source
AI summary
A method for automatically calibrating an external force measuring device of an industrial robot. The industrial robot has a multi-axis robot arm, the robot arm has, for each joint axis, an electric actuator (M1, . . . M6) and a position sensor (C1, . . . C6) able to measure the joint position of the corresponding joint. The robot has a force measuring device. The force measuring device has at least one measuring sensor capable of measuring the forces applied to the robot arm. The method updates an applied force correction coefficient by incrementing it with a value proportional to the average force of the external forces exerted if certain conditions are met.