LJ Create - Customer Support

It is important to calibrate the robot on the computer it is to be controlled from so that it works within the required tolerances. A robot that has not been set up correctly will move clumsily, with a lack of precision, and any control programs will not run with repeatable accuracy. If the robot is moved to another computer the calibration must be performed on the new computer.

The table below shows the required settings for the four joints:

To calibrate the robot, the control software has to be run in calibration mode to store the settings on the computer. The robot can be re-calibrated by re-running the software in calibration mode. Note, the student can access the calibration controls, but they will only be able to make changes for the current session. When the Robot Control software is run again it will revert back to stored settings.

For a direct connection from the RoboTEK Robot to the parallel port on a PC, the PC must be set to a uni-directional mode. Some manufacturers may refer to this as SPP mode, others as AT mode. This is configured using the PCs CMOS set up program. Refer to the documentation supplied with your PC for information on how to make the changes.
Customers using the LJ USB adaptor do not need to perform this step.

Procedure

1. Run the Robot Control software in calibration mode by running: "C:\Program Files\LJ Create\Robotics and Automation\RobotCon.exe" setup
2. Select 'Control Hardware' from the Robot menu. Once the robot is detected, select 'Set-up Robot' from the robot menu.
3. Enter the Robot ID (IJxxxx found on the robot).

Backlash

This removes most of the errors in movement when the robot changes direction. These errors are due to mechanical backlash in the joints.

1. Use the Robot Controls to move the robot to B45 S100 E45 J45.
2. Select the Base in the Set-up Robot window. Alternately operate the two Robot Control Base keys to move the joint. If the robot does not move, increase the backlash compensation number. Try the control keys again. Repeat the process until the robot moves. Now try moving two steps forward and back. The movements should be equal. If you have overdone the backlash compensation, the first step after changing direction will be too big. You will probably find a backlash compensation of 2 or 3 is about right for the base.
3. Repeat the process for Shoulder, Elbow and Jaws. You will probably find that the shoulder and elbow need little or no compensation, whereas the jaw needs 4 or 5 clicks.

Offset

The spatial position of the robot jaws can be adjusted to correspond to a known position as set by the Robot Control position numbers.

1. Put a part in Dispenser A. Use the Robot Controls to move the robot to B77 S35 E44 J100. This is a critical position for the robot. It should be somewhere near the position required to pick a part from Dispenser A.
2. Select the Base in the Set-up Robot window. Look down on the dispenser from above and see where the jaws are in relation to the tube. They should be nearly central. Adjust the offset number until the jaws are as close as possible to a central position.
3. Select the Shoulder in the Set-up Robot window. Look at the dispenser from the front, along the line of the tubes. Adjust the offset number until the jaws are central with the part in the dispenser.
4. Use the Robot Controls to close the robot jaws until they are just about to grip the part. Make small adjustments to the Shoulder and Elbow offsets to ensure that the part will be gripped properly.

Minimum and Maximum Joint Positions (Optional)

This prevents the Robot Control numbers incrementing or decrementing above or below a number where the robot joint does not move.

1. Minimum position - move the arm so it is over the conveyor and clear of any obstacles.
2. Move the base to its left-most position. You will probably find that the base stops before the numerical position has reached minimum. Move the base to the right, one step at a time, until it just starts to move. Click the Minimum Set button to store this position.
3. Maximum position – now move the base fully round to the right. Step it back to the left until it just starts to move, then click the Maximum Set button. 
4. Repeat the process for the other joints.
5. Click Save to store the settings.