Robo Roadie

Purpose

I've got this RockNRoller cart thing that's basically a dolly/cart with collapsible arms that can be extended, and is great for hauling speakers and heavy musical equipment around. It's very handy as is, but I don't really use it all that much. What would motivate me to use it more? If it were motorized and remote control from my cellphone, of course!

Parts

If you count the cost of the cart then this is a pretty expensive project. I've had the cart for years though. This could work with just about any wheeled cart you can round up, assuming you're willing to figure out how to mount the motors to it.

1 x Rock N Roller R10RT cart - $185
2 x Auto Power Seat Motors - $30
2 x 8" Pneumatic Tires+Wheels - $16
2 x Hobbywing Quicrun 1060 ESC - $40
1 x Arduino Nano - $4
1 x Arduino Nano I/O Shield (not required) - $8
1 x HC-06 Bluetooth Adapter - $8
1 x 5v BEC (not absolutely required) - $8
1 x 12v Battery (I used a 3S Lipo) - $15
1 x Android phone/tablet to control over bluetooth - ???
1 x Blueberry Android App - free

So, total cost not including the cart was about $130. With that particular cart, around $310 I guess.

Description

Here's what I wound up with:


Here's what I started with:


I'll upload a video as soon as I get a chance to video it in action.

So I took off the back wheels and mounted some fairly powerful motors onto it. I used two power seat motors for cars. They're great because:

1. they're cheap (around $15 on Amazon)
2. they're easily powered by 12vdc
3. the housing is not grounded (unlike most power wiper motors), so they're reversible without shorting out via the metal frame.

Here's a link to what I got, though I'd recommend looking for an "Amazon Prime" version if you can find it:


https://www.amazon.com/gp/product/B005IR1NBA/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

I used a couple of wheels+tires that I got from Freight Harbor. It's 8", supposedly non-marring, and is fairly easy to adapt to the motors I've got by using some hardware from Lowes. I used a 0.5" sleeve to get it to snug down pretty tight on the motor shaft.


An Arduino Nano and a I/O shield handle the logic, and a cheap bluetooth adapter (around $8 on amazon) handles the communications from the controller. I use my Android phone as the controller, and the app Blueberry does a great job of collecting speed/direction via screen presses.

Inexpensive Arduino Nano on Amazon:


https://www.amazon.com/gp/product/B015MGHH6Q/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

The Nano I/O shield:

https://www.amazon.com/gp/product/B011U8G1JO/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

The bluetooth adapter:


https://www.amazon.com/JBtek-Bluetooth-Converter-Serial-Communication/dp/B00L08GA4Q/ref=sr_1_1?s=pc&ie=UTF8&qid=1471211629&sr=1-1&keywords=bluetooth+hc06

The Blueberry app:
https://play.google.com/store/apps/details?id=com.bluetooth&hl=en#details-reviews

That app "Blueberry" is really cool. It won't work by just installing and pairing it, you have to code for its heartbeat signals. That's a really good thing though. That way, if the Arduino quits responding then the app almost immediately notices it, and it disconnects. Also, the Arduino will know very quickly if the app has disappeared. It helps to keep this Robo Roadie from going berserko and breaking ankles. It's definitely powerful enough to do great harm to an ankle should it get loose.

To drive the motors I used some inexpensive reversible brushed speed controllers. I've used these on several projects and they're reliable and fairly powerful. The Hobbywing Quicrun 1060 - around $20 per wheel.


https://www.amazon.com/gp/product/B00LXCM3Q8/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

For power, I use whatever 3S Lipo battery I've got charged up. They can be had for $15 or so from HobbyKing. It runs for a long time on a 5000Mah 3S battery. I also used a separate BEC to get the ~12v down to 5v for the arduino+bluetooth adapter. I could probably use the BEC that's built into the ESCs, but I've pretty much decided to quit trusting ESCs for 5v. Separate BECs are so cheap (around $8), I'd rather just use one and know for certain that I'm going to get around 5v. I used a Dr. Mad Thrust 3A BEC that also has an on/off switch that you can use to turn on/off another device, like headlights.


http://www.hobbyking.com/hobbyking/stor ... ouse_.html



My Arduino code does the following:
- connects to the bluetooth adapter via software serial
- waits for a connection from an external device (Blueberry)
- watches for speed commands, remaps/mixes them, and sends them out to the speed controllers

The code is here:
https://github.com/nshaver/roboroadie