Robot Error Parameter Calibration with Fewer Measurement Positions
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Solution Overview
Problem
Existing robot calibration methods require driving the robot to multiple positions to calculate numerous mechanism error parameters, which can be impractical due to limited motion ranges and result in prolonged downtime, reducing factory productivity.
Innovation Solution
A calibration apparatus that selectively invalidates certain mechanism error parameters, allowing the robot to be driven at fewer positions using other parameters, measures actual positions with a three-dimensional device, and recalculates the invalidated parameters without altering others, reducing the number of measurement points and calibration time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all mechanism error parameters are calibrated by driving the robot to multiple positions, then the accuracy of robot control is improved, but the calibration time and downtime are prolonged
Solution Approach 1:
The calibration process is segmented into two stages: first calibrating selected mechanism error parameters, then calibrating the remaining parameters. This segmentation allows the robot to be driven to fewer positions in each stage, reducing the total calibration time while maintaining accuracy.
Solution Approach 2:
Instead of calibrating all mechanism error parameters simultaneously, the invention applies partial action by calibrating only selected parameters in the first stage. This reduces the number of measurement points required and shortens calibration time, while the second stage completes the calibration of remaining parameters.
2Measurement precision
If the robot is driven to multiple positions to calculate all mechanism error parameters, then the control accuracy is improved, but the motion range requirements increase
Solution Approach 1:
The calibration process is divided into stages where only selected mechanism error parameters are calibrated in the first stage. This segmentation reduces the requirement for large motion range, as fewer measurement points are needed. The robot can be driven within a limited range while still achieving accurate calibration for the selected parameters.
3Measurement precision
If numerous mechanism error parameters are calculated using multiple measurement positions, then the calibration accuracy is improved, but the productivity of the factory is reduced
Solution Approach 1:
The invention applies partial action by calibrating only selected mechanism error parameters in the first stage rather than all parameters. This reduces the time the robot is taken out of service, minimizing impact on factory productivity. The remaining parameters are calibrated in a second stage, balancing accuracy requirements with productivity concerns.
Solution Approach 2:
By segmenting the calibration process into multiple stages with different parameter sets, the invention reduces the duration of each calibration session. This allows the robot to return to production faster, thereby maintaining higher overall factory productivity while still achieving accurate calibration.
Data Source
AI summary
A robot controller includes at least one memory that stores a plurality of mechanism error parameters including a first mechanism error parameter and a second mechanism error parameter. At least one processor of the robot controller acquires an actual measurement position and information on a status of a robot by driving the robot with a plurality of orientations at a plurality of positions based on the second mechanism error parameter. The at least one processor calculates a third mechanism error parameter by correcting a value of the first mechanism error parameter based on the acquired actual measurement position and information on the status of the robot. The robot is controlled based on the plurality of mechanism error parameters including the second mechanism error parameter and the third mechanism error parameter.