sophiecentaur said:
It really would help to know whether this thread is discussing how this system is being achieved by Bosch or how to make a better one. If the latter, then it is necessary to state exactly what you want it to do. A specification is needed if you want to avoid even more wasted effort here. Inanimate circuit elements need to be told exactly what to do before you will have a working machine and design can only result from a properly stated requirement. What are your actual requirements for this, petter? You keep shifting the goal posts and randomly picking out ideas and systems.
Are you prepared for a network of buried cables? Do you want just cables around the perimeter? Is this machine just for your garden or do you want to create a design that can be used commercially for many different gardens? Will all these gardens have their own cable systems? If not, then why are we discussing a system with buried cables? Without them, you will need a map of every garden to be treated.
Please give us something concrete to address. (Actually, some green concrete could solve the problem of grass cutting for ever!)
(I got interrupted by work, so the reply had to wait)
The way I work with projects is to look at what have been done with similar applications before - what have worked, what have not. That gives a lot of ideas for solutions. Some of which may conflict. Currently there seems to be three possible directions to go:
1) The border-loop-wire
2) The RF transmission line
3) The radio
Some ppl in the thread talk about one or two of these. Others talk of only one. The thread may seem a bit chaotic as subject is changing between those technologies. Maybe the technologies should be combined in the final system, or maybe we can exclude some?
Spec (ideally):
- Be able to calculate position (within 30cm error) and direction heading (within 3 degrees) for any location of the robot within an area of 20m from the cable, or a square of size 30x30m
- calculation of one of the two (position or direction) should be within limits even when obstacles like a house, a car, a person, are located between signal sender and receiver
- robot needs to know how accurate calculations a any given moment are. That way it can go for calibration and/or put a higher trust other methods like counting wheel rotations.
- total length of wire to dig down should not be more that 150m
- if system requires radio senders placed around or within the area, cables to these are included in the 150m limit.
- ground is not flat. There has to be taken in account that ground plane varies with +/- 50cm. robot height is max 40cm. Sensors can be placed high or low on the robot.
- there are 4 wlan senders around the area and 2 inside the area. At least 3 senders has coverage at any location. They can be used, but not modified.
- System should work independent on weather conditions and light conditions. Components that are not suitable for outdoors use need to work even when put in a box.
- System should not make sounds that can be heard by humans, or lights visible to humans.
- System should not disturb other electrical systems. Including an equal system installed next door.
If it works out in the end, I guess this may turn into some kind of DIY-kit-list that can be distributed.
(Green concrete solves the grass cutting, but not leaf blowing or snow blowing.)