Pre-calibration Checks
To ensure the accuracy of the calibration result, please first complete the following checks before hand-eye calibration:
Confirm that the robot base is mounted securely
Before checking the accuracy of the robot, please check whether the robot is securely mounted first. An unstable robot base will cause the robot to shake when it moves, which will affect the repeatability of the robot. This affects the reliability of subsequent robot accuracy checks.
Please make sure that the robot mounting meets the following requirements:
-
The ground where the robot body is installed is smooth and tidy.
-
The base of the robot body should be designed to ensure stability during operation at 100% full speed.
-
Make sure that the robot body and mounting base are fastened by screws.
Check method: Check whether the base and body of the robot shake significantly by translating or rotating the robot at 100% speed. If so, please secure the robot according to the robot mounting requirements.
Confirm that the camera mounting frame and camera are mounted securely
Before hand-eye calibration, please ensure that the camera mounting frame and camera are mounted securely. You should perform the following checks:
-
Check the material and structure: The camera mounting frame should be a machined part; aluminum profiles should not be used. The frame should have a reasonable structure and provide stable support.
-
Check if the camera mounting frame is securely mounted.
Check method: Manually shake the frame to see if the frame shakes significantly. The camera mounting frame is considered qualified if it does not shake significantly.
-
(If a camera sliding mechanism is used) Check whether the camera slide mechanism on the frame is secure and accurate.
Check method: Move the camera sliding mechanism back and forth to test for shaking and positioning repeatability. If no shaking is observed after the sliding mechanism is in place, the positioning repeatability meets camera requirements.
-
Check if the camera is securely mounted.
Check method: Please check whether the camera and its cables are properly mounted by referring to Camera Mounting Requirements and Guidelines for Mounting Camera Cables.
Confirm that the calibration board is mounted securely at the end of the robot (ETH)
For the automatic calibration and manual calibration (Multiple random calibration board poses) in the Eye to Hand (ETH) scenario, the calibration board should be mounted at the end of the robot.
Check method: Manually shake the calibration board. If there is no noticeable movement, the calibration board can be confirmed as securely mounted.
For other calibration scenarios and intrinsic parameter checks, there is no need to mount the calibration board. Please place the calibration board in the center of the object plane. For the manual calibration (TCP touch), the calibration board must be secured to the work surface to prevent any movement when the robot touches the points.
Confirm that the absolute accuracy of the robot meets the requirements for use
Checking the absolute accuracy of the robot typically requires specialized equipment such as a laser tracker and calibration software. Before deploying the vision solution, you need to check the robot absolute accuracy yourself or contact the robot manufacturer to check it and output the robot absolute accuracy check report.
The evaluation of the robot absolute accuracy is highly complex. Mech-Mind only provides several common qualitative evaluation methods. For detailed instructions , please refer to Check the Robot Absolute Accuracy.
Verify Robot Model Parameters
| To verify the parameters of the robot model, you need to compare the pose in the software with the pose of the robot teach pendant. Therefore, before validating the parameters of the robot model, please complete the robot accuracy checks to ensure the accuracy of the robot pose data on the teach pendant. |
If a big difference between the simulated robot pose or tool pose in the software and the real robot pose is observed, for example, one to two meters, the robot model parameters may be inaccurate and need to be corrected.
For detailed instructions, see the Guide for Robot Model Parameter Verification.
Confirm That the Camera Is Warmed Up
The camera temperature drift phenomenon will affect the values of each dimension of the point cloud, and affect the repeatability and absolute accuracy of the camera.
Therefore, the camera needs to be warmed up before hand-eye calibration. You can warm up the camera by one of the following methods:
-
Connect to the camera via Mech-Eye Viewer software or Mech-Eye API and capture images continuously for more than 30 minutes. Warm-up for more than 45 minutes for high-accuracy applications;
-
Power on the camera and keep it in standby for more than 40 minutes.