What is the difference between robot repeatability and absolute positioning accuracy? On-site judgment methods

The fact that a robot can return to the same position multiple times does not mean that position perfectly matches the theoretical coordinates in the offline program. Understanding the difference between repeatability and absolute positioning helps in determining whether a problem stems from mechanical condition, zero point, or coordinate calibration.

1. Key Points to Check
2. Repeatability focuses on the dispersion after running the same path multiple times, commonly used for evaluating production stability.
3. Absolute positioning accuracy focuses on the difference between the commanded coordinates and the measured coordinates, affecting offline programming and cross-station positioning.
4. Reducer backlash, bearing wear, and structural looseness typically reduce repeatability stability.
5. Mechanical zero point, robot parameters, load model, and base coordinate errors significantly affect absolute positioning.
6. Implementation Steps
7. First, fix the tool, load, speed, acceleration, and approach direction to avoid changes in test conditions.
8. Select multiple poses and measurement points within the workspace, run repeatedly, and record the dispersion range.
9. Compare results from single-direction approaches with those from different approach directions to determine if mechanical backlash exists.
10. After maintenance or relocation, reconfirm the zero point, tool coordinates, workpiece coordinates, and any necessary accuracy compensation.
11. Common Misconceptions
12. Judging the entire robot's accuracy state by testing only one point.
13. Changing speed, load, or approach direction during testing, making results incomparable.
14. Mistaking coordinate calibration errors for reducer wear and directly replacing mechanical components.
15. Summary

Repeatability reflects the consistency of a robot returning to the same point multiple times, while absolute positioning accuracy reflects the deviation between the commanded position and the actual spatial position. Their purposes and inspection methods differ.

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