Eye to hand Six-Axis Robot Calibration

About 3850 wordsAbout 13 min

This article explains how to perform eye-hand calibration in an Eye to hand setup with a six-axis Robot.

1. Random Pose Sampling Calibration

1.1 Preparations Before Calibration

Before eye-hand calibration, complete the following preparations:

（1）Complete 3D vision guidance kit hardware setup

Please refer to 3D Vision Guidance Kit Hardware Setup to complete the installation and connection of the Robot, Camera, and industrial PC

（2）Create a new Project and task

Please refer to Project Operation Guide and task Operation Guide to create a new Project and task

（3）Complete Camera connection, Parameter adjustment, and task information configuration

Please refer to Camera Connection and Parameter Adjustment Guide to connect the Camera, perform camera imaging quality adjustment, verify Camera accuracy, and configure it in the task information

（4）Complete Robot communication configuration

Please refer to Robot Configuration and Communication Operation Guide to establish the robot communication connection between the Robot and PickWiz

（5）Prepare the materials required for calibration

Ensure that the Calibration Board is flat and clear, with no obvious scratches or dirt, and no bending or deformation
If the calibration method is Random Pose Sampling Calibration, ensure that the Calibration Board is placed on the work platform and is within the Camera field of view.

1.2 Calibration Information Configuration

Go to the eye-hand calibration interface and click Add Eye-Hand Calibration to open the calibration information configuration interface

Calibration Name can be used to name the current calibration configuration
Calibration ID is used by the Robot to switch calibration configurations
Camera is the IP address of the currently connected Camera
Camera Brand is the brand of the currently connected Camera
Robot Type must be consistent with the Robot type in Robot Configuration
Camera Installation Method select Eye-to-Hand
Calibration Board Type select the current Calibration Board type

The appropriate Calibration Board mainly depends on the Robot type and the Camera mounting height. Refer to the table below and select the proper Calibration Board according to the actual application scenario.

Robot Type	Camera Mounting Height	Select Calibration Board
Six-axis Robot	Below 0.5 m	A6 multi-concentric-circle Calibration Board
	Below 1.5 m	A5 multi-concentric-circle Calibration Board
	1.5 m -- 2.5 m	A4 multi-concentric-circle Calibration Board
	Above 2.5 m	A3 multi-concentric-circle Calibration Board
Three-axis/Four-axis Robot	Below 0.5 m	A6 multi-concentric-circle Calibration Board
	Below 1.5 m	A5 multi-concentric-circle Calibration Board
	1.5 m -- 2.5 m	A4 multi-concentric-circle Calibration Board
	Above 2.5 m	A3 multi-concentric-circle Calibration Board

Calibration Method select Random Pose Sampling Calibration
If the Robot has a corresponding calibration program and needs to run that program to send the pose to PickWiz while sampling the Calibration Board, then for Get Coordinates Online** select Yes; if the Robot does not have a corresponding calibration program, you need to manually enter the pose of the Robot end tool while sampling the Calibration Board, then for Get Coordinates Online **select No.

1.3 Pre-calibration Checks

Ensure that the Robot base is securely installed

Before eye-hand calibration, carefully check the installation of the Robot base. If the Robot base is not securely installed, the Robot may shake noticeably during motion, affecting Robot accuracy and therefore the calibration result.

Check whether the Robot base installation meets the requirements as follows:

First, the surface on which the Robot base is installed must be flat and clean;

Second, operate the Robot at 100% speed with large translation or rotation movements and observe whether there are signs of shaking. If shaking occurs, readjust and secure the Robot base to ensure that no displacement or tilting occurs during Robot motion;

Third, check whether the Robot body and base are tightly connected, and tighten the screws to prevent loosening.

Ensure that the Camera and its bracket are securely installed

Before eye-hand calibration, carefully check the installation of the Camera and its bracket. If the Camera or bracket is not securely installed, Camera imaging quality may be affected, which in turn affects the calibration result.

Check whether the Camera and its bracket installation meets the requirements as follows:

First, check whether the Camera bracket is a machined part. Aluminum profile material should be avoided for the bracket;

Second, shake the bracket and observe whether there is any obvious wobble. If so, readjust and secure the bracket;

Third, shake the Camera and observe whether there is any obvious wobble to ensure that the Camera is securely installed.

Ensure that the Calibration Board is stably placed within the Camera field of view

For Eye to hand Camera mounting, mount the Calibration Board on the end tool and ensure that the Calibration Board is within the Camera field of view.

Ensure that Robot accuracy meets the Project requirements

If Robot accuracy does not meet the Project requirements, please refer to Calibration Verification to correct Robot accuracy.

1.4 Collect Samples

1.4.1 Collect multiple sets of Calibration Board and Robot coordinates

（1）Control the Robot carrying the Calibration Board to move so that the Calibration Board is positioned at the center of the Camera field of view and is parallel to the Camera imaging plane.

（2）Click Start Sampling. The Start Sampling button changes to Stop Sampling. The Inspection Results below displays two categories of checks: Camera and Robot. If all Camera checks and Robot checks show green icons, the checks pass. If any red icon appears, the check has failed and should be inspected.

（3）The Camera checks cover 4 aspects:

（4）The Robot checks cover 3 aspects:

（5）When coordinate axes appear on the Calibration Board in the visualization window and the center of each concentric circle is green, the current Calibration Pose meets the requirements.

（6）Click New Sample. If the sample is valid, a Sample Validity Check Passed pop-up dialog appears. After clicking OK, Collected Samples displays the Sample 1 label. Click Sample 1 to view the saved sample, or click the close button after Sample 1 to delete the sample.

If the sample is close to an existing sample, it is invalid. A Sample Check Failed pop-up dialog appears with the message Close to Existing Sample. Click Back, then control the Robot carrying the Calibration Board to move and collect the sample again.

（7）Control the Robot carrying the Calibration Board to move so that the Calibration Board is positioned at the four corners of the Camera field of view, and the rotation angles about the X, Y, and Z axes are all greater than 10°. Repeat the sample collection steps above until at least 10 samples are saved.

（8）After at least 10 valid samples are saved, click Finish Collection to enter the Calculation Results interface.

1.4.2 Calculate the Calibration Result

Click 计算结果. PickWiz calculates the calibration result based on the collected samples. If the accuracy of the calibration result does not meet the requirements, perform Calibration Result Inspection and Analysis.

1.5 Calibration Result Inspection and Analysis

If the Calibration Error exceeds the normal range, the cause of the error must be identified. Click Calibration Diagnosis and refer to Calibration Result Inspection and Analysis to analyze the calibration result, resolve the issue, and check again until the calibration accuracy meets the application requirements.

1.6 Select the eye-hand calibration configuration

After the calibration Procedure is complete, return to the Run Configuration interface, click Task Information, click the Eye-Hand Calibration drop-down list, and select the corresponding eye-hand calibration configuration.

2. Needle-Tip Calibration Tool Point-Touch Calibration

2.1 Preparations Before Calibration

Before eye-hand calibration, complete the following preparations:

（1）Complete 3D vision guidance kit hardware setup

Please refer to 3D Vision Guidance Kit Hardware Setup to complete the installation and connection of the Robot, Camera, and industrial PC

（2）Create a new Project and task

Please refer to Project Operation Guide and task Operation Guide to create a new Project and task

（3）Complete Camera connection, Parameter adjustment, and task information configuration

Please refer to Camera Connection and Parameter Adjustment Guide to connect the Camera, perform camera imaging quality adjustment, verify Camera accuracy, and configure it in the task information

（4）Complete Robot communication configuration

Please refer to Robot Configuration and Communication Operation Guide to establish the robot communication connection between the Robot and PickWiz

（5）Prepare the materials required for calibration

Ensure that the Calibration Board is flat and clear, with no obvious scratches or dirt, and no bending or deformation
If the calibration method is Random Pose Sampling Calibration, ensure that the Calibration Board is placed on the work platform and is within the Camera field of view.

2.2 Calibration Information Configuration

Go to the eye-hand calibration interface and click Add Eye-Hand Calibration to open the calibration information configuration interface

Calibration Name can be used to name the current calibration configuration
Calibration ID is used by the Robot to switch calibration configurations
Camera is the IP address of the currently connected Camera
Camera Brand is the brand of the currently connected Camera
Robot Type must be consistent with the Robot type in Robot Configuration
Camera Installation Method select Eye-to-Hand
Calibration Board Type select the current Calibration Board type

Robot Type	Camera Mounting Height	Select Calibration Board
Six-axis Robot	Below 0.5 m	A6 multi-concentric-circle Calibration Board
	Below 1.5 m	A5 multi-concentric-circle Calibration Board
	1.5 m -- 2.5 m	A4 multi-concentric-circle Calibration Board
	Above 2.5 m	A3 multi-concentric-circle Calibration Board
Three-axis/Four-axis Robot	Below 0.5 m	A6 multi-concentric-circle Calibration Board
	Below 1.5 m	A5 multi-concentric-circle Calibration Board
	1.5 m -- 2.5 m	A4 multi-concentric-circle Calibration Board
	Above 2.5 m	A3 multi-concentric-circle Calibration Board

Calibration Method select Needle-tip Tool Touch Calibration
If the Robot has a corresponding calibration program and needs to run that program to send the pose to PickWiz while sampling the Calibration Board, then for Get Coordinates Online** select Yes; if the Robot does not have a corresponding calibration program, you need to manually enter the pose of the Robot end tool while sampling the Calibration Board, then for Get Coordinates Online **select No.

2.3 Pre-calibration Checks

Ensure that the Robot base is securely installed

Check whether the Robot base installation meets the requirements as follows:

First, the surface on which the Robot base is installed must be flat and clean;

Third, check whether the Robot body and base are tightly connected, and tighten the screws to prevent loosening.

Ensure that the Camera and its bracket are securely installed

Check whether the Camera and its bracket installation meets the requirements as follows:

First, check whether the Camera bracket is a machined part. Aluminum profile material should be avoided for the bracket;

Second, shake the bracket and observe whether there is any obvious wobble. If so, readjust and secure the bracket;

Third, shake the Camera and observe whether there is any obvious wobble to ensure that the Camera is securely installed.

Ensure that the Calibration Board is stably placed within the Camera field of view

For Eye to hand Camera mounting, place the Calibration Board on the work platform and ensure that the Calibration Board is within the Camera field of view.

Ensure that Robot accuracy meets the Project requirements

If Robot accuracy does not meet the Project requirements, please refer to Calibration Verification to correct Robot accuracy.

2.4 Collect Samples

2.4.1 Collect Calibration Board and Robot coordinates

（1）Adjust the position of the Calibration Board, place it within the workpiece placement area, and click Start Sampling.

（2）Click Add Sample. If the sample is valid, a Saved Successfully prompt appears. If the sample is close to an existing sample, the sample is invalid and the save fails.

（3）Check the detection results. If all check items are green icons, coordinate axes and feature points appear in the visualization window, and all circle centers are green, the current Calibration Pose meets the requirements.

The checks cover 4 aspects:

2.4.2 Touch the Calibration Board with the needle-tip Calibration Tool

（1）Click Start Sampling, control the Robot to move, and use the needle tip to touch the center of each corresponding concentric circle in the numerical order shown in the visualization window.

（2）Click New Sample to collect the Robot coordinates at the moment of point touching.

（3）Repeat the steps above to collect at least 3~6 concentric-circle point-touch samples.

Click Next

2.4.3 [Optional] Add a new Calibration Pose

During the calibration sampling stage, the system uses a single Calibration Pose mode by default, but in specific application scenarios it can be extended to a multi-position calibration strategy, improving calibration robustness and system adaptability under complex working conditions:
For accuracy deviations caused by depth-of-field changes in wide-angle vision systems, layered sampling along the Z-axis can effectively balance the error distribution across different focal planes;
For work environments with limited space, when a single Calibration Board placement cannot complete the collection of more than three feature points, multiple Calibration Board placements and separate sampling can be used to cumulatively satisfy the minimum sample quantity requirement.

Click New Position to add a new calibration position, then repeat 2.4.1 Collect Calibration Board and Robot coordinates and 2.4.2 Touch the Calibration Board with the needle-tip Calibration Tool to collect calibration samples and perform Calibration Board point touching.

Robot Configuration and Communication Guide

Deep Learning Module Usage Guide

How to Use Shadow Mode