Temperature Drift Compensation in Industrial Robot Manipulators
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Solution Overview
Problem
Industrial robots experience positioning drift due to temperature changes, leading to reduced repeatability and accuracy, as existing calibration methods fail to account for temperature-dependent effects across the entire workspace.
Innovation Solution
A method to correct manipulator parameters by determining and overcompensating for changes over time, using the first and second derivatives of parameter changes to minimize temperature-induced drift, allowing for precise positioning throughout a work cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard temperature drift compensation is used, then initial positioning accuracy is maintained, but residual drift accumulates over the work cycle due to continuous heating
Solution Approach 1:
The system performs preliminary characterization of temperature drift behavior by measuring robot positioning deviations at multiple temperatures throughout the work cycle. This preliminary data is used to pre-calculate compensation values that are applied before the actual work cycle begins, allowing the system to proactively counteract expected drift rather than reactively correcting it during operation.
Solution Approach 2:
The invention transforms the static robot model parameters into dynamic parameters that vary with temperature. By establishing temperature-dependent parameter sets through preliminary measurements and using interpolation to determine parameters at intermediate temperatures, the system adapts its control parameters in real-time based on the current thermal state, thereby maintaining positioning accuracy throughout the work cycle.
2Loss of time
If calibration is performed only at the beginning of the work cycle, then setup time is reduced, but positioning drift increases during the cycle due to temperature changes
Solution Approach 1:
The system performs comprehensive temperature drift characterization and parameter optimization in advance, before the actual work cycle begins. This preliminary calibration phase includes measuring positioning deviations at multiple temperature points and calculating optimal compensation parameters. Once this preliminary work is complete, the system can execute the main work cycle without additional calibration steps, achieving both time efficiency and maintained accuracy.
Solution Approach 2:
The system incorporates feedback mechanisms where positioning measurements taken during the work cycle (or in preliminary characterization) are used to update and refine the temperature-drift compensation model. This feedback loop allows the system to learn from actual drift behavior and improve its compensation strategy, ensuring accuracy is maintained without requiring frequent interruptive recalibration.
3Adaptability or versatility
If extreme poses are used for calibration, then coverage of temperature effects is attempted, but blind spots in the workspace remain where drift is not compensated
Solution Approach 1:
The invention creates a universal compensation model that is valid across the entire workspace, not just at specific calibration poses. By performing measurements at multiple poses and temperatures and using interpolation techniques, the system generates a comprehensive set of temperature-dependent parameters that can compensate for drift anywhere in the workspace. This universal model eliminates the blind spots that would exist if only extreme poses were calibrated.
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 approach significantly reduces residual errors and maintains high accuracy, achieving positioning precision better than +0.15 mm by continuously adjusting parameters to match the ideal state throughout the cycle.
Implementation Method 1
By friction in the mechanical elements of a robot and by waste heat from electrical components changes the temperature of robot mechanics. This can lead to a change in the size of the individual elements
Implementation Method 2
By friction in the mechanical elements of a robot and by waste heat from electrical components changes the temperature of robot mechanics
Implementation Method 3
waste heat from electrical components
Data Source
Figure 1~2
AI summary
The invention relates to a method for correcting a manipulator-parameter, wherein a manipulator is controlled at least by means of a manipulator-parameter. A change in the manipulator-parameter is determined over time and a residual error in the positional precision of the manipulator is corrected using the specific change in the manipulator-parameter over time.