FPV Micro RC Car

by sdfgeoff Feb 16, 2019
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Hello! I'd love to make this project, and have the modified servos. I read in some of the previous comments that you accomplished this using an ESP32. Would you mind sharing a brief description of how you did this? and if at all possible your code for the ESP and how you control it?

Really appreciate any help you can provide! especially with the ESP32, it's a fantastic little module.

You can find the code for it here: https://github.com/sdfgeoff/esp-remote-control

However, It's probably best to make your own method of control, because I built the transmitter/controller as well. So it doesn't provide a normal wifi network/web interface. The protocol doesn't even send valid wifi packets....
So, instead of copying that (which is bound to a specific bunch of hardware), I strongly suggest using micropython and writing your own control mechanism.

If you do try to replicate my controller, the transmitter expects potentiometers/control sticks on pins 32, 33, 34, 35. The ESP inside the crawler expects the servos to be attached to pins 25, 26, 27 and 14. These mappings can be found in the "hardware.py" file inside both the esp32_receiver and esp32_transmitter folders.
The binary files are uploaded inside the esp32 folder (you can flash them with esptool), and if you need to modify the code the build time requirements are the same as for the ESP-IDF and micropython.

Let us know how you get on!

how exactly did you fit the wheels on the servos? i seem to be to stupid to work that out :/

I used the servo horns, but cut the legs off to the right size. I then glued those in place with superglue.

Ohhh I see. Didn't think about that.
I thought about putting a silly long screw through the hole in the wheel into the servo...

Thank you!

I wonder if you could make a mold and then make some DIY Sugru to make the wheels

I tried this out the other day and made some flexible tracks for a tank-like vehicle (tracks are https://www.thingiverse.com/thing:3448240 vehicle will be uploaded soon enough). Once I've finished that I may well make some moulds for this one.

Silicone rubber tracks (3d printed moulds)

excellent and simplified!

How fast can it go?

If you use unmodified SG90 servos, it goes a theoretical 0.9kph (aka quite slow). If you do a speedhack on them (remove the fourth gear and glue the third and fifth together) you get a ~9x speed increase bringing the speed to about 8kph. And if you're 4cm above the floor in a vehicle the size of your hand, 8kph is plenty fast enough - borderline uncontrollable. However, with speedhacked servos, it struggles when going off-road and the motors get quite hot.

With N20 motors, this depends on the RPM you buy. To get the same 8kph or so from an N20 you'll need one with a RPM output of about 1000RPM, which are easily available from China.

If I were to build the N20 version, I'd probably pick 600RPM motors, I think this would offer a good balance between speed (about 5kph) and climbing ability.

Thanks. Also could you put links to where you got the other supplies?

Hmm, not really. Most of it was just what I had lying around at the time (eg the batteries were from a pair of cordless screwdrivers), and the electrical setup I have here is quite different to what most people would want (I didn't use a normal radio control set, but built my own using ESP32 modules). So I think it's better for people to source their own components.

K that's fine