Today I’d like to write a short post about my plans concerning my board project.
Right now I have almost working board with very simple “control unit” with LCD to display motor’s temperatures (by “almost working” I mean being able to ride for about 5-10 minutes, then some mechanical part breaks). Batteries are mounted using transport strap, wires are attached to the board using adhesive tape, to make it ready to ride I have to connect 4 plugs. But it’s just a first prototype to check whether my idea is viable (i.e. building a reliable board with brushless motors using only 3D printer and generic tools – no milling machine and welding).
So here’s my plan for the next 1-2 months:
- Mechanical part of the project:
Mainly power transmission problems – I have troubles attaching sprocket wheel to the motor’s shaft in a reliable way. But after today’s tests I hope that I need to make just minor improvements to my design and I will be done with that problem.
Second mechanical issue is bearing the motors and shafts. As I mentioned in my previous post, recently I added shaft’s support on second end to eliminate moment load). After quick tests I noticed that the bearing I added was getting a bit too warm (but I haven’t measured it exactly yet) – that’s probably due to the fact that there are 2 bearings inside the motor and adding third bearing makes one of the bearings overly loaded (due to inaccuracies in bearings position on the shaft).
If I manage to fix these two problems I will probably done with the mechanical part – at least I hope so, but probably a few other problems will show up.
- Electronics part of the project:
Right now I only have attached thermometers to the motors. I’m planning to add temperature measurement to the motor’s drivers, a GPS, current sensors (two, one for each motor), batterie’s voltage measurement.
My initial plan is to use Arduino Mega as the “brain” of the whole board (but I’ll probably write code in C++, without using Arduino “framework”/libraries). I already have an LCD 192px x 128px. The display will be mounted in front part of the board in a 3D-printed case. I will also add “ignition switch” to eliminate tiresome connecting connectors.
Aforementioned ignition switch will connect power (from small Li-po) to the Arduino, which will make sure the main batteries are connected and it will turn on IGBTs, which will be located between batteries and motor’s drivers. I will describe this in more detail in one of future posts. I still haven’t figured out how I’ll charge the batteries (how to make it the least tiresome)
- Designing cases/mounts
I’ll have to create cases for control unit (already started) , batteries and motor’s drivers. So far I have printed mounts for drivers, but I already see that I’ll have to redesign them (I didn’t consult additional space for board with IGBTs).
I also want to make proper lighting – both for safety and better style. To test my design idea I printed and assembled one back light, render and real photo:
Obviously there’s a lot to be done yet, but I’ll never give up – I’ve already sacrificed too much time and money for this project to surrender.