If you can show some pictures of the assembled parts and unassembled components, I can better tell the next step.

Could you show the current assembling state?

Have you tried the latest firmware and the desktop app? A video of the robot's boot up behavior will help us investigate the problem. If the problem persists, you can email support@petoi.com to schedule a remote session.

Hi, you may also write to support@petoi.com and we can take a look at your serial communication.

The Arduino source code uses many pointers and classes to improve efficiency and fit in the chip's limited storage. Some algorithms were written when I was preparing for the interview with Google. The tricks to combine complex cases into one-line conditions can take hours to explain. in Variables that may also correlate with many files and the circuit.  Even I will make mistakes when modifying the source code. So it takes a lot of work to explain the code. It can be a thick book.  To make it easier for people interested in Arduino programming, there's also a simpler interface that only requires an understanding of the application layer. It's the taskQueue method. It uses the same serial command rules in an altered format and can run directly within the Arduino source code. You can refer to the extensible modules, and check how the robot can read sensor data and react within the scope of a single file. For example, you can activate the macro of DOUBLE_TOUCH, and the code defining all its behaviors is in src/doubleTouch.h.

It was merged with the new graphical user interface. I just updated the link.

Hi, You have tried good methods to debug. Here's a complete routine to locate the problem: https://docs.petoi.com/technical-support/faq-frequently-asked-questions#the-robot-servos-dont-seem-to-be-working.-how-to-debug-the-servos There's a spare servo in the package for timely fix. Meanwhile, please write to support@petoi.com to request a replacement.

The new architecture is better structured to separate modules into different header files. The main workflow is in OpenCat.ino or OpenCatEsp32.ino.

Yes, that's also bionically proper arrangement. balancing is not handled by the brain.

The balancing is implemented in motion.h, the adjust() function. It's based on simple proportional control. The adjustment should happen very fast. I took a short clip on March 21, 2022. In the demo, Bittle takes large strides, almost its body length per step. It utilizes the faster CPU of ESP32 (compared to Uno) for real-time balancing. Bittle was not well launched to the ground, but it corrected itself in the first several steps. I doubt if the communication with Pi will be this fast.

Very detailed documentation and explanation on the codes. Thanks!

I also believe it's based on simple feedback. I think NyBoard can handle walking with a proper algorithm. However, it may be easier to start experimenting with more advanced algorithms on the BiBoard. You may need four analog input pins for your sensors. NyBoard only has A2 and A3 pins accessible, while A4 and A5 are used for I2C.

The current gait is tuned to be fast and stable on smooth surface.

I've uploaded the file: https://github.com/PetoiCamp/NonCodeFiles/blob/master/stl/Bittle_FrontPlate.stl

Hi, Could you send a video to show the abnormal behaviors to support@petoi.com

The main cause of the instability is the scratching between the feet and the carpet. To walk on the carpet, Bittle needs to lift its feet higher in the swing stage. To avoid instability, it should also reduce the distance of each step.

One reason that we deactivate the gyro is because of Uno's limited programming space. The BiBoard with extension hat has enough programming space. But it has to disable the voice control module to use the ultrasonic sensor. We are also designing a better version to better support Nybble.

The servo angles can be larger. When it becomes larger than 125, an angle ratio of x2 will be calculated. It's stored in the skill array: https://docs.petoi.com/applications/skill-creation#data-structure Considering the servos' precision, the resolution loss from 1 to 2 degrees won't be a big problem. And we don't need to double the data size to achieve similar performance. Note the servo has a limited controllable range of 270 degrees. I've shifted the midpoints to give Bittle the maximum accessible working space. Some 360-degree servos are not really 360-degree controllable but will continuously rotate when given edge angle instructions.

Cool! Please search for OpenCat Bittle when adding the product details on Hackster. I used Bambu P1S to print your structure. Residues of the support materials on the side make the columns hard to insert. I suggest cutting the bottom to adapt for 3D printed structures. I also noticed the two clippers are a bit loose. I'll check the original model to see if I can fix it.

You can refer to this list: https://docs.petoi.com/apis/serial-protocol