Veterans of the Power Racing Series or Hacky Racers might have expected to see a Chinese motor controller in the mix, but instead he’s used a set of relays for simple on-off control. The traction control has a pair of 3D-printed sensor wheels that operate upon a corresponding pair of optocouplers to provide feedback to the NodeMCU. A set of different drive options were tried, with finally an H-bridge board being found to be most reliable.
The video below the break shows the hardware, and goes into some detail on the software. The NodeMCU’s WiFi is used to provide some tweakability to the system on the go. The traction control turns out to lower the standing start speed a little, but makes the machine more controllable by its driver. he certainly seems happy with his toy!
And greatly increases the torque exerted on the hubs, shafts and any plastic gears, making it necessary to upgrade those as well…
i wouldn’t say necessarily – I’ve got another model, found old garden tractor tires fit over the stock plastic wheels nicely. Between higher rotating mass, (much) more traction, 24V PWM control (<= 70% duty), two kids in it, and being second hand with plenty of wear, I still haven't had gear/hub issues. Huh, the 'soft start' PWM ramping i built into the control logic probably helped a lot though come to think of it… Was more to reduce whiplash for kids on takeoff to not slam on the gas as the mechanical switch did, but bonus of reducing drivetrain stress.
Those drive units are readily available and surprisingly cheap, normally with a 65W 12v motor attached. I’ve often wondered how much abuse the gears could take were I to take a bunch of them and make a multi wheel skid-steer Hacky Racer, but don’t want to waste a wad of cash just making broken gear teeth.
I sort of have memories from when I was a kid involving hotmelt glue treads… But maybe that was trying to repair the wheel?
Fyi. The old motor had a tachometer. This is strong evidence that the electronic control box was probably already ramping speed and limiting torque. Also, the price difference between a 6v motor power stage and a 12v motor power stage is tiny. I’d give good odds that the only difference with the OEM 12v system is a 12v battery, charger, and moving a voltage jumper on the microcontroller.
This is a cool project, no doubt about that. The smile of the little kid and the near-miss with the parked car together with the blown FETs every time the motor was switched off make it all a joy to watch. Unfortunately… this is a re-run:
Sorry Jenny, but Dan covered this story almost 15 months earlierhttps://hackaday.com/2018/03/18/traction-control-gets-more-power-to-the-road-for-tot-sized-lamborghini/
I was reading this article and was thinking we must be screwed in Australia. I have a 4wd style car for my kids with twin motors and run it on 12v rather than 6 and it’s still gutless, we must just get the real crappy ones here. There is no way my car will spin it’s wheels on anything but wet ice.
Hi , I have the exact same unit for my son but it green in colour. Have changed the 6V battery twice. Need some help on where I can get the motor for this unit and the battery specs for the 12V unit. On the same note could a more power ful motor be utilised. Thank you.
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