Most R/C equipment comes packaged for a single specific use, which makes it easy to use but is very limited in what you can do with it. So using the Arduino as an interpreter between the R/C system and the motor driver, I can use any motor controller that I want (depending on the size of the motor and power required), reprogramming the Arduino to supply the required signals.

What I ended up with:

After successfully hacking a few R/C cars from the thrift store, I got bored driving them around the driveway and I was having a hard time convincing my wife that there was any usefulness in the revived toy car. So I decided it was time to make my biggest chore at home, a whole lot easier and actually put my Arduino to work, and thats how I ended up building an R/C lawnmower.

While designing the lawnmower, I thought it would be cool to learn about the electronics that made it move, so I designed and built my own motor speed controller (or H-bridge) to power the lawnmower. I looked around at every H-bridge design I could find before deciding to go with a Mosfet h-bridge that uses both N-channel and P-channel Mosfets.

I built several different motor driver boards for this project, the first two were on Radio-Shack perf-board and the next 4 were designed using EagleCad and etched to a piece of copper-clad PCB, using the toner-transfer method. The most recent board is the one I use to mow the lawn as it has the ability to stay cool even while operating for long periods of time (30-40 mins straight) at 10-20amps and 24vdc. FWIW, I had to burn up a lot of Mosfets to find this out. If you want to see any of my other motor controllers, go to www.rediculouslygoodlooking.com and check out the Mosfet shield.

Here is what I bought already assembled:
- FM R/C transmitter and receiver pair from ebay = $40
- Arduino = $30
- I already had a used push-mower = $60

Here is what I bought and assembled into the Lawnbot400 (as I call it):
- (2) electric-wheelchair motors from ebay = $40 ea
- (2) 12v marine deep cycle batteries – Walmart – $60 ea new (used batteries might work)
- 36″ pieces of 2″ angle-iron (2) and 1″ square-tubing (2) from Home Depot = $8 ea
- 36″ pieces of 1″ angle-iron (2) and 1″ flat steel bar (2) from Home Depot = $5 ea
- (a lot) of nuts, bolts, washers, lock washers 3/8″ or 1/2″ with drill bit = $20
- (2) caster wheels from Harbor Freight Tools = $14 ea
- (2) drive wheels from Harbor Freight Tools = $8 ea
- (36″) 5/8″ threaded rod with several 5/8″ nuts and washers from Home Depot = $8
- (2) sprockets from Allelectronics = $5 ea
- #25 roller chain and a few universal links from Allelectronics = $10 for 3′
- sprockets from Electronics Goldmine = $1.50 ea
- (24) mosfets from Digikey = $1 ea
- (there were quite a few small parts for building the H-bridge, they are listed later on)