This kit from Germany presented me with the first advantage ever for Brexit. No VAT to pay as we are outside the EU, and no duty or VAT when entering the UK - perhaps I was lucky! Nicely packaged including a screwdriver and hex key. Easy to construct, although the lock washers could be stronger - I have had a few **** drop out during operation - perhaps a spanner should also have been supplied. Shame the construction notes had wrong info on the placement of the motor brackets (now corrected). The motors and cables are sturdy, and the processor pcb looks well made. I havn't given it 5 stars because of various gotchas. The advertising has now been corrected to say that this is definitely not a toy, but a development platform - the self-balancing algorithms need careful tuning for it to work, and it is quite a powerful robot that can go flip-flopping all over the floor and bash into furniture until you stabilise it. I had to modify the software to display real time data on the screen to help with tuning. It can provide serial port diagnostics, but that needs a USB lead attaching, so not suitable for free roaming. The software loop delays have to be carefully managed to avoid FIFO overflow in the self-balancing calculations running in the background. I also have various other problems, such as uploading code from a MacBook Arduino app is hit and miss. It seems that the Elektor folk have only used Windows machines and say that they havn't had any difficulties. I find that pressing the boot and reset buttons and releasing before the upload can almost guarantee no error, but I hope the small buttons don't wear out. I am struggling to get turning left and right working, as the self-balancing algorithm tends to mask any speed inputs. The software to use the ultrasonic distance sensors is not yet implemented. It's good value as a sturdy development kit for PID software controlled motors so I have given it 4 stars. I am hoping that the forthcoming article(s) in Elektor will help those folk with less experience than me (retired Spacecraft engineer).
