Tiny Trak iNav

By virtual_stephen on Nov 02, 2020

26  894  1

First item of business - yes there are no rotors on this build. But I think it's still worth a mention as it's a little unusual. This was inspired by the Tiny Trak concept which is a 3D-printed miniature tank shell with either two continuous-rotation servos or two N20 motors for drive motors. Lego components are widely used and they are typically driven using just two channels with a mixer on the radio.
However. I build quads and I started small, so I have a box of old small recievers, flight controllers and VTX/camera combos. I also really hate programming mixers on my radio. This is 2020, microcontrollers are everywhere and I don't stick my builds together with paper and glue.
How hard can it be to repurpose a whoop board to drive a tank? Not hard it turns out, as long as you never want to drive in reverse. Yeah, those brushed whoop boards can't reverse the motors. Just not an option. I even got a turtlebee out of curiosity as it claimed turtle-mode which means it'll reverse the motors right? Wrong.

Anyhow, this developed into a full iNav build minus GPS (because indoors) but it's got a VTX with OSD, beeper, current meter, 8 LEDs for headlamps and a nano FrSky RX.

I used a tutorial from the excellent Pawel Spychalski to convert yaw into a thrust vector and enable this to turn on the spot. https://quadmeup.com/inav-for-tracked-rovers/

iNav 2.5.2 is used with a rover mixer and both motors connected to "servo" type output to enable programming within iNav. The Star Trak top was chosen as it offered the most space and ventilation, plus it's less boring that a regular box on wheels.

The Lego parts can be hard to find in shops but plenty of people sell them on ebay. The DasMikro B type was used (dual independent ESC without mixer). 3mm wide * 4mm long N52 magnets were forced into the sides of the 3D print to attach the two halves without using screws.

300RPM 6V N20 motors were used to provide a bit of speed with enough torque to climb obstacles.

11/11/2020 - UPDATE - Added OLED screen for status info.

Using iNav's "display" feature I connected a 0.96" 128x64 pixel OLED screen showing battery status. If GPS is enabled this screen can show location and satellite lock also. (photographing the OLED is tricky as the camera tends to capture moments when the screen is re-drawing which hides the edges of some characters, it looks fine to the naked eye).
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Imray   Nov 04, 2020  

i want one.

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