This instructable will be about building a fpv rover with the following components:
Pololu Zumo Rover
2CH RC Rx/Tx
ImmersionRC 25MW TX
ImmersionRC UNO Rx base station
GoPro or any other camera that outputs analogue video
Pololu states on their webpage, that their ZUMO shield only runs with the UNO.
I tried the MEGA, as it shares all pins except the additional pins of the MEGA, so i would advice you to use the UNO.
Also for the fpv Tx/Rx combo, feel free to use any you have at hand.
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Step 1: CHASSIS/SHIELD/LIBRARY
The assembling of the Zumo shield is nice and fast, you only have to solder around 5 pieces to the chassis to make it run.
After that, make sure you have downloaded and installed the ZUMO library
There is a walkthrough how to install it at Pololu's homepage
With the library, they ship a lot of example scripts, one is called "RCControl"
The script assumes that there is an RC connected (next step) to the Arduino.
It then reads the two channels (Left/Right) (Forward/Reverse) interprets them and remaps the values for a tracked vehicle.
So for you it behaves like a "normal" RC Car with a steering wheel, and the arduino does the rest.
I had to change the script and using 51/53 as input pins, because i use the MEGA which has 51/53 layed out on the edge of the controller, so i can reach them easily.
Step 2: CONNECT THE RC TO THE ARDUINO
To connect the Rx with the arduino you need four pins of the Rx:
- One of the Rx's 5V Pins to power the Rx
- One of the Rx's GROUND Pins also for powering the Rx itself
- The Signal Pin of the First Channel
- The Signal Pin of the Second Channel
The reason why i wrote "one of the .. 5V Pins" is that all 5V Pins on the Rx are connected, also all GND Pins are connected which each other.
The Receiver gets power by those pins, but also spends power to servos for example.
In short: you can use any of the 5V pins and any of the GND pins, to connect them to the 5V and GND pins of the Arduino (see sketch)
Next step is to connect the two Signal pins to the two Arduino input pins that you defined in the script.
Thats it, power the system up and here we go :)
Step 3: CHANGE THE SYSTEM TO LiPo
To add a LiPo battery you have to know a few IMPORTANT facts.
Most of you probably know, for the rest of you:
A LiPo can explode.
A LiPo can set itself on fire, thats immune to water, aka you need a fire extinguisher
How can this happen?
SHORTAGE and LOW VOLTAGE
How does this affect our project ?
- First of all, if you use a 2S that you got laying around and don't use anymore, and if you decide to give it new connectors, so it fits your Arduino project: NEVER EVER let the two cables touch each other. Be extremely careful when soldering them and cutting them.
- Next important thing is: never empty them fully. How you will know that ? Easy: INSTALL LIPO ALARM. Thats a small board that constantly reads the voltage in your battery and tells you(or shuts off power) when the LiPo should be reloaded.
Most of the devices that are made to be powered by a LiPo already have this security alarm built in, the ZUMO doesn't. Its also not planned to run with a LiPo.
Which LiPo to take ?
Thats pretty easy, a single LiPo Cell hast 3,7Volts.
The Zumo should be powered by 4xAA aka 6V, so if we put 2S LiPo in there, it has 7.4V, just a bit too much.
I tested it with 1S, and with 2S, with 1S it runs like on 4xAA, with 2S it's fast :)
For installing the LiPo Alarm, just connect it in parallel to you Battery, and you are safe.
Step 4: ADDING FPV
FPV, stands for First Person View, that means beeing able to see what the rover sees in real time, via wireless video connection.
There are a lot of different Systems out, using different carrier frequencies.
The one most people use, also the one i use operates in the 5.8GHz band.
Your RadioSystem runs on 2.4GHz, so they do not interfere.
I use the ImmersionRC 25MW Transmitter, that can be powered by 2S, so i just put it in parallel to the rest of the rover.
For a connection you have to get analogue video out of the GoPro, which might cost you 25€ for a cable, or a 10Pin mini USB plug and some soldering skills. As i couldn't get the USB plug, i bought the cable.
Next you can either solder a cinch socket to the ImmersionRC Tx, or cut the cinch plug from the GoPro cable and solder them directly together.
After you did that, you can pack everything on the zumo, and youre ready to go.
One thing to take care of, is that in my version the Immersion Tx always gets power by the LiPo, even if the ZUMO is powered off.
If you dont like that, solder an on/off switch to one of the ImmersionRC Tx's power lines