This is my first post here and I'd like to start by saying BIG thanks to @Rongzhong Li for all the work he has done and his readiness to share the source code.
I 3d-printed OpenCat Nybble published on Thingiverse and assembled it. It works as expected with IR remote when MPU6050 is disabled. As soon as I enable it, cat starts doing a lot of extra moves that appear to be random.
I purchased MPU6050 in local electronics store and initially had some issues with it. I2C scanner finds it at correct address but getDeviceID reads incorrect code. I also had problems with calibration. Numbers 123456 would never appear. Then I tried all different things and after adding some random code into getDeviceID, like writeByte into readonly register, it started to work by some reason. So I have big suspicion that MPU6050 is partially faulty, but before replacing it I'd like to know what should be the difference in cat behavior with and without accelerometer. Right now it is turned off and I'd like to understand whether I even need it or not.