RC Snowmobile

TL;DR: I build a low-cost tracked vehicle with a ESP32-CAM module, which can be controlled via WIFI with an Open Source Android app ESPHomeRC.

snowmobile_lq.mp4

The Hardware

Bill of Materials

You need:

• an ESP32-CAM module like this

• a platform with tracks and motors like this

• an H-bridge module like the MDD3A

• 2-4 Li-Ion 18650 batteries like these and a holder

The Assembly

Connect the H bridge to the ESP32 like this:

ESP Pin	H Bridge
GPIO14	M1A
GPIO15	M1B
GPIO12	M2A
GPIO13	M2B
5V	5V
GND	GND

       

       

The Firmware

The firmware is completely open and easily hackable. It is based on . You just describe your setup in a yaml file and a firmware will be generated.

Preparation

Install

Build and upload

Get a 3.3V USB to serial adapter (like this) and connect it:

ESP Pin	... to
GPIO0	GND
3.3V	3.3V
VCR	RX
VCT	TX
GND	GND

esphome run snowmobile.yaml 

The software

Then you can control your vehicle with this Open Source Android app ESPHomeRC.

An example for the javascript controller running on your android device is given here:

outp = {};
outp.display = "Hi from everest controller, I am running because " + 
                inp["reason"] + " at " + inp["timestamp_ms"] + " ms";
        
if (typeof i == "undefined") {
    i = 0;
}

i++;
outp.display += " i=" + i +"\n";
//outp.log="log " + i + "  " + inp.user.x + " " + inp.user.y; 

var fwd = inp.user.y * 2.0 ;
fwd = Math.max(Math.min(1.0, fwd), -1.0); //limit to +-1.0

var lr = inp.user.x;
if (Math.abs(lr) > 0.3)
  lr = lr * 1.5;
else
  lr = 0.0;
  
var left = fwd + lr;
var right = fwd - lr; 

outp.hbridge = [
               {"index":0, "strength": -left * inp.user.aux0 , "brake":false}, 
               {"index":1, "strength": -right * inp.user.aux0, "brake":false},
               {"index":2, "strength":  inp.user.aux1, "brake":false},
];

outp.user = {};
outp.user.aux_labels=["vmax", "light"]; // aux0 = vmax, aux1=light
outp.user.interval_ms = 10000 ;// regular interval to call this script, 0 means as fast as possible...