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[on:]

Hi,
Yes, you read right, I really do want to talk about a lawn mower.
I was just in B&Q and there was this lawn mower unlike anything I've seen.
Theres no handle, or cable as far as I can tell. It consists only of a flat device,
 about the size of a suitcase, on 3 wheels with a cutter beneath. Basically it's
a robot and it trolls around the lawn on its own. And it costs about 1000 quid.
I think I'll buy two.
I wondered, as you do, how this thing works. How does it know where the lawn is,
 or the edges or anything. Will it eat the dog? Next-door's cat? God I hope so. And
 can I make one with an Arduino and some old pram wheels?

bruce

[Reply #1 on:]

The ones I have seen use the same "invisible fence" transponders that dog collars use. It might work like a roomba though, you would just need to program the boundary once, and it would still be able to navigate around things inside that area.

[Reply #2 on:]

The one I have has a perimeter wire which carries a signal.

[Reply #3 on:]

Thanks for that. So, it could operate in a number of ways.
Our garden is so higgley-piggledy I cant see either method working very well.
At present we have a low-tech method of automatically cutting the lawn:
two rabbits and two guinea-pigs.

Bruce

[Reply #4 on:]

I was just in B&Q and there was this lawn mower unlike anything I've seen.
Theres no handle, or cable as far as I can tell. It consists only of a flat device,
 about the size of a suitcase, on 3 wheels with a cutter beneath. Basically it's
a robot and it trolls around the lawn on its own. And it costs about 1000 quid.
I think I'll buy two.

I don't know what the current rates are, but at that price, it would seem to me that you could hire the local kid (assuming kids these days still cut lawns for spending money) to cut your lawn for 1-2 years.  So figure maybe 40 hours/year, assuming you live in an area that has winter, and that grass cutting season is maybe 30 weeks, but you will have extra hours at the beginning for cleanup, and extra hours in the fall for leaf rake up.  I'm more familiar with US $, so 1.000 quid is perhaps 2,000 US $.  If you pay for one year's service, that would be $50/hour, but if you figure two years service, that would be $25/hour.  It changes somewhat if you hire professionals to do the work.  We have people to cut our grass, but I don't know what they charge, since my wife does the books.

[Reply #5 on:]

Thanks for that. So, it could operate in a number of ways.
Our garden is so higgley-piggledy I cant see either method working very well.
At present we have a low-tech method of automatically cutting the lawn:
two rabbits and two guinea-pigs.

Bruce

It is quite flexible, there is a way of placing the wire to form islands around bushes/ ponds etc, only thing is it does not like is sharp corners.
Best to have the lawn flat though, mine is quite steep and the batteries need replacing every year.
Makers claim about 200+ charge cycles but never had that.

Pay someone, no arguments on cost , but its my toy.
Also a bit worried here that said kid may be 'casing the joint'.

[Reply #6 on:]

What makes you think the mower isn't collecting data on you, watching your every move?  Sending covert messages to forward the plans of our rapidly coming Robot Overlords?

I recently had to "dispose of" an end table and spent six hours interrogating an eleven speed mixer, after I noticed they were getting a little bit TOO comfortable listening in on my phone coversations. 

You really cannot be too careful.

(maybe I ought to go take my pills now, twitchtwitch)

[Reply #7 on:]

I for one welcome our robot lawn mower overlords.

[Reply #8 on:]

I blame myself.
I had to build an interossiter shield when "Them" told me to.

[Reply #9 on:]

(maybe I ought to go take my pills now, twitchtwitch)

Tinhat, not pills. The pills will make you think there is no problem, the tinhat will prevent the problems.

[Reply #10 on:]

What makes you think the mower isn't collecting data on you, watching your every move?  Sending covert messages to forward the plans of our rapidly coming Robot Overlords?

I wish!

If that is indeed the case, I'll get one of these lawnmowers too, just to speed things up for the coming of the robot overlords.

Do you think those overlords are "Intel Inside"?

[Reply #11 on:]

Thanks for that. So, it could operate in a number of ways.
Our garden is so higgley-piggledy I cant see either method working very well.
At present we have a low-tech method of automatically cutting the lawn:
two rabbits and two guinea-pigs.

Bruce

Use a shovel to make a slit in the dirt and bury a couple meters of wire a few inches down. Pulse DC through the wire (makes a changing field as opposed to a static field, say 10 to 100 short pulses per second) and see if you can detect it with a Hall sensor.

If you can get it to work then use 3 sensors to make a line-follower robot, the robot follows the path laid out. Only THEN should you think about whirling cutting blades and more sensors to stop for objects/animals.

[Reply #12 on:]

HC-SR04 ultrasonic sensor a.k.a. Bat-Mod
Featured in: http://apcmag.com/arduino-project-4-enhancing-your-mini-robot.htm
Integration could be possible.

[Reply #13 on:]

can I make one with an Arduino and some old pram wheels?

How would you spin the Arduino fast enough to cut the grass?

g'heh...   

[Reply #14 on:]

LOL! Makes me think of a POV display board!