Industrial Robot Force Sensor Drift Calibration by Feedback
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Solution Overview
Problem
Industrial robots equipped with external force measuring devices face issues due to force sensor drift over time, leading to erroneous measurements and potential robot anomalies, such as unwanted movements, unless regular corrections are applied.
Innovation Solution
A method for automatically calibrating the external force measuring device by calculating and updating a drift correction coefficient based on successive measurement cycles, considering indicators of force variation and joint position changes, to maintain accurate force measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force sensor drift correction is applied regularly, then measurement precision is maintained, but device complexity increases due to frequent calibration requirements
Solution Approach 1:
The system performs self-calibration by automatically detecting when the robot arm is in a known reference position (home position) and autonomously adjusting the correction coefficient without requiring external intervention or manual calibration procedures
Solution Approach 2:
The system continuously monitors force sensor readings and compares them against expected values based on robot state, using this feedback to automatically update the correction coefficient when drift is detected
2Measurement precision
If manual correction of force sensor drift is performed frequently, then measurement precision is maintained, but loss of time increases due to operational interruptions
Solution Approach 1:
The calibration process occurs continuously in the background during normal robot operation without requiring operational interruptions, maintaining measurement precision while eliminating downtime
Solution Approach 2:
The system autonomously performs calibration without requiring operator intervention, eliminating the time operators would spend on manual calibration procedures
3Measurement precision
If correction coefficient is updated continuously, then measurement precision is maintained, but productivity decreases due to excessive processing
Solution Approach 1:
The correction coefficient is updated periodically only when specific conditions are met (robot at home position, stable readings confirmed over multiple cycles) rather than continuously, maintaining precision while minimizing processing overhead
Solution Approach 2:
The system uses feedback from position sensors and force sensor stability checks to determine when calibration is actually needed, avoiding unnecessary updates that would reduce productivity
Data Source
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AI summary
A method for automatically calibrating an external force measurement device of an industrial robot (2), said industrial robot comprising a multi-axis robot arm (4), the robot arm comprising, for each articulation axis, an electric actuator (M1,...,M6) and a position sensor (C1,...,C6) capable of measuring the joint position of the corresponding joint, the robot comprising a force measurement device (20), the force measurement device (20) comprising at least one measuring sensor capable of measuring the forces applied to the robot arm. The method allows updating a correction coefficient for the applied forces by incrementing it with a value proportional to the average of the external forces exerted if certain conditions are met.