Tuesday, April 26, 2016

Arduino Rover Part 1: Initial Plan and Reverse-Engineering.

It's been a while since I've last posted... About nine months. I'll have to get into the habit again.

A few weeks ago, I picked up the Arduino Uno that I've had for a while, and started thinking about what I should build with it. I decided on modifying an old toy rover that I had, and making it wirelessly drivable... but with 2 way audio and a camera feed.

Here's the original rover (Sorry for the low resolution. I don't have any pictures prior to disassembly... Mine was missing a headlight anyway.) It's a shark Kid Galaxy Morphibians toy:
In this first part of several posts, I will be explaining about the insides of this rover after I got clever with a screw-driver.

Links:
Part 1: Initial Plan and Reverse-Engineering
Part 2: Preparing the Rover Chassis
Part 3: Motor Control
Part 4: Bluetooth
Part 5: Mounting
Part 6: Batteries
Part 7: The Test

The first part of disassembly was undoing six screws on the bottomside of the rover. Removing these allowed the top and bottom halves to come apart.

Inside the rover, power wires and antenna connected to a plastic box housing the brains... I couldn't crack it open for fear of breaking everything inside. Then, wires went to two motors, one for each side of the car. After a few glances and attempts to strip the motor wires, it became apparent that all of the wires were both threaded and very thin. Attempts to put them in a breadboard were very discomforting to say the least.



On the physical layout side of things, the battery box, the brain box, and the gearbox took up almost all of the interior space. Not very easy to insert electronics with room to spare. The gearbox was in the middle-bottom, and the battery container was directly on top, eliminating that space almost completely. The brain was at the back, cushioned by foam. Since that's naturally going to have to go, that would seem to be a very good location for batteries to power the Arduino. No way I'm going to be taking the risk of crushing the Arduino itself back there.

I did try to take the gearbox apart, but it reeeally didn't want to open. There might even have been glue inside.



Surprisingly, there were also several more pieces of foam below and around the gearbox, suggesting that the advertising for this particular rover was telling at least part of the truth about potential amphibious capabilities. I'd always kept it out of water anyway, for fear of short circuits.

This rover seems to be pretty well engineered... Too well if I'm going to try to fit my Arduino and a breadboard inside (I'm not).

Part 2 will be about removing the guts and solving the wire-breadboard compatibility issues. It'll involve some soldering.

Until then, I do have some tips on how to go about doing this yourself.

1. There are several different versions of the Kid Galaxy Morphibians... I think Sharks and Gators were the first two to be released. Their internal layout will very likely be the same on all of them.

2. Don't try to open up the brain-box or the gearbox. They're very difficult and you will probably just damage them.

3. This might belong in the Part 2, so I'll put it there too: The motor wires connect to different wires from the brain box via solder. The heat-shrink tubing wasn't connected very well on mine, so I could slide that away from the solder, and after snipping the wires on the brain-box side of the connection, I could just slide the insulation right off.

Edit: 4/28/16: Updated last image
Edit: 5/9/16: Added list of links
Edit: 5/11/16: Updated list of links
Edit: 6/1/16: Updated list of links
Edit: 7/8/16: Updated list of links
Edit: 8/25/16: Updated list of links
        Got bored of just saying "Updated list of links" every single time...
Edit: 7/6/17: Updated... list of... PARTS