Petoi Doc Center
Joint Calibrator
Robots can be precisely calibrated using the Petoi Desktop App.
The pre-assembled robot should already have the legs properly installed but not fine-tuned.
Make sure you have uploaded the OpenCat "Main function" firmware before calibrating. Only the 2.0 version of the firmware is supported.
If you are building the robot from a kit, do not install the leg components until calibration. You also need to install the battery and long-press the button on the battery to power the robot.
After the USB adapter or Bluetooth module is properly connected, open the Petoi Desktop App (for Windows: UI.exe / for Mac: Petoi Desktop App), select your model and language, then click the "Joint Calibrator" button to open the calibrator interface.

The Joint Calibrator interface

Note: Since Nybble uses two more servos (head and tail) than Bittle, the joint index numbers of Nybble and Bittle servos are different, and the calibration poses of Nybble and Bittle after entering the calibration state are also different, as shown in the following picture( The servo slider is not available in the light yellow background area in the interface):



1. Click the "Calibration" button, and all servos will move to the calibration position immediately.
If you are building the robot from a kit, Install the servo-related components according to the picture at the bottom of the interface, and try to ensure that they are perpendicular to each other (the upper leg is perpendicular to the torso, and the lower leg is perpendicular to the upper leg). Please refer to the related chapter in the user manual for the details:
2. Use the included L-shaped tool as a reference during calibration. According to the index numbers of the joints shown at the top of the interface (when calibrating the servos, adjust the upper leg first, then adjust the lower leg). Drag the corresponding slider (below the index number), or click the blank part of the slider track to fine-tune the joint to right angles.
If the offset is more than +/- 9 degrees, you need to remove the corresponding leg and re-install it by rotating one tooth, and then drag the corresponding slider. For example, when it is adjusted to +9 and is still not right, remove the corresponding leg and shift one tooth when attaching it. Then you should get a smaller offset in an opposite direction.
You can switch between "Rest", "Stand up" and "Walk" to test the calibration effect.
You may need to do a second round of calibrations to achieve optimal results.
After calibration, remember to click the "Save" button to save the calibration offset. Otherwise, click the "Abort" button to abandon the calibration data. You can save the calibration in the middle in case your connection is interrupted.
When you close this window, there is a message box shown below:
if you want to save the calibration data, please click the "Yes" button, otherwise click the "No" button. Click the "Cancel" button to cancel to quit.
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