Robot Calibration Device Using Preliminary Position Evaluation

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Solution Overview

Problem

Current calibration methods for industrial multi-jointed robots face challenges in automatically determining the optimal position and orientation for measurement, leading to low positioning accuracy and inefficiencies due to external equipment interference and high calculation complexity.

Innovation Solution

A calibration device and method that includes an aligning part, initial position designation, preliminary position determination, judgment, and correction to ensure the robot's position and orientation satisfy predetermined conditions, using a camera for automated alignment and evaluation to improve accuracy and reduce calculation time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If automated position determination is implemented, then calibration efficiency is improved, but positioning accuracy deteriorates due to inability to ensure optimal positions

Engineering Contradiction:
Improvecalibration efficiencyVSAvoidpositioning accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The system performs preliminary determination of robot positions and orientations before actual calibration measurement. Multiple candidate positions are pre-calculated based on the error model, and the optimal position is selected in advance to ensure both automation and measurement accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses an error model to evaluate the quality of preliminary determined positions and provides feedback for optimization. The evaluation results guide the selection of optimal measurement positions, ensuring that automated determination achieves high positioning accuracy.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If optimal positions are manually determined, then positioning accuracy is improved, but calibration time increases due to complex calculation and external interference

Engineering Contradiction:
Improvepositioning accuracyVSAvoidcalibration time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces manual mechanical determination of calibration positions with an automated computer-based system. The computer automatically calculates optimal positions and orientations based on the error model, eliminating manual intervention and reducing calibration time while maintaining high positioning accuracy through algorithmic optimization.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If multiple measurement positions are used, then calibration accuracy is improved, but device complexity increases due to need for precise position control

Engineering Contradiction:
Improvecalibration accuracyVSAvoidposition control complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system determines both position and orientation of the robot simultaneously using a unified error model approach. This multi-functional determination method allows multiple measurement positions to be utilized effectively without increasing control complexity, as the same computational framework handles both positional and orientational parameters.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP1953496B1Calibration device and method for robot mechanism
Publication Date: 2019.05.15 FANUC LTD
  • EP1953496B1 patent drawingFigure 1~2
  • EP1953496B1 patent drawingFigure 3~4
  • EP1953496B1 patent drawingFigure 5

AI summary

A calibration device and method for automatically determining the position and the orientation of a robot used for measurement. First, an initial position of a preliminary position is generated based on a designated basic position, and it is judged whether the initial position is within an operation range of the robot. If the robot cannot reach the initial position, the preliminary position is adjusted close to the basic position. Otherwise, the preliminary position is evaluated by calculating an evaluation index of the preliminary position. When the evaluation index does not satisfy a predetermined condition, an initial value of an posture angle is increased.