Autonomous boat ferry.

Hi,

A friend of mind is trying to interest me in a project for him. He lives on an island in a lake, and uses a small electric boat to ferry himself and the family the 100 meters to and from the island. The problem is that they've only got one boat, and with family members constantly coming and going the boat is always in the wrong place. They've experimented with applying RC to the boat, but it's not been 100 successful.

I've worked with GPS's and compasses in the past and rekon I could easily design a project that could navigate the boat to within a few meters of the boathouse, the tricky bit would be get it to manage the last 10-20 meters. My current plan is a bright light above the door to the boathouse, and a 2nd light at the back of the boathouse. If the arduino can 'see' the two lights and one light is vertically above the other then it must be accurately lined up with the entrance, ifthe lower light is to the left of the upper light then the boat is too far to the left and needs to steer right, if the lower light is to the right of the upper light then the opposite applies.

This all relies on a sensor that can 'see' the two lights. I've never done any form of image processing, but I understand it takes a fair bit of processing power, possibly more than the arduino can provide.

Does any suitable sensor exist? is is there a better way of doing this project?

All suggestions welcome.

I would go with three light beacons. A triangle is always going to be more accurate.

For image processing, I would look into the work done to interface the Wii remote camera. It has built in "blob" detection which is perfect for this application.

I would go with three light beacons. A triangle is always going to be more accurate.

Good point, didn't think of that, two lights one above the other would be subject to errors when the boat rocks from side to side.

Yep. With three lights, you can sense 3D space quite accurately. The Wii IR camera works in the IR range and you are going to need some pretty bright IR beacons since it is not designed for far away use. Also consider what conditions you may encounter in foggy or heavy rain weather. Some type of manual override would also be a good idea. You certainly wouldn't want to leave people stranded on the island if things go apeshit.

A directional antenna and 2.4GHz would help be able to control the boat remotely. Have the antenna on a type of tripod on the island side that would allow them to reposition it if necessary.

Also, what if the battery on the boat dies while on the mainland side? I suppose an emergency inflatable raft kept on the island would take care of that.

This is why I wouldn't live on an island. lol. Though in worst cases, a 100M swim is not too terribly hard.

Also, one trick to avoiding interference is to pulse the lights at some frequency, say 1KHz. Then you would be able to filter out any stray light sources that may cause false triggers. Even MORE anal would be to encode each beacon with a different frequency. Then you could also sense which beacon was which for cases where you may be coming in from an odd angle. But with the GPS, I think you will get reasonably accurate control of at least that much.

Also, what if the battery on the boat dies while on the mainland side?

Both sides have power.

I suppose an emergency inflatable raft kept on the island would take care of that.

They have canoes.

A directional antenna and 2.4GHz would help be able to control the boat remotely

The intention is that the controller would be mounted on the boat, not on the shore.

pulse the lights at some frequency, say 1KHz

Good idea, but shouldn't be required. Don't think there are any other light sources in the vicinity.