Three Strand Boundary Wire

[veritas]

First, I am sorry not to be able to use your French language, but robotic lawnmowers have not yet become popular enough in England to have given birth to any forums and I am inquisitive before I purchase.

I study your forum through a Google Translator and you can imagine how difficult this is, but still very rewarding compared to sales information from the manufacturers. If your administrator demands it, I can translate this into French using GoogleTranslator before I post it again, but I am sure this will lead to great misunderstandings.

I am now over 70 years old, retired, and finding our 1000sq meter complex garden lawn a burden using a 21 inch walk-behind mower. So I am greatly attracted to robotic cutting and a bit less so to ride-ons as alternatives. Both will leave plenty enough handwork for me.

Husqvarna/Gardena or Belrobotics/Etesia are my two favourites. One part of my garden connecting front to back only 2 meters wide, so I have formed the view that I may need the extra support offered by a guide wire which the Belrobotics/Etesia system seems not to have.

However, the Belrobotics/Etesia system uses a three-strand boundary wires (red/blue/yellow). From your excellent posting on computer simulation I am already familiar with the magnetic field generation from the more common single strand boundary and guide wires, so I am left wondering what three wires would do differently. Can anyone shine a light on this system as a whole?

The diagram in the Beltronics Installation guide shows how to wire an island if you wish the robot to ignore it on the return journey which I assume must normally travel along the whole boundary wire.


I would be very happy with any responses in the French language and I will Google a translation to English for myself.

[JPMalef]

Hi, Welcome,

No need for translation.
To my knowledge, Etesia is a Belrobotics mower with a few 'improvements', but those robots are made for very large surface. This is probably the raison for the three-strands wires, but usually, the way it works is not documented to users._o_

For your 1000 sqmeters, a Gardena/Husqvarna will do.

If you can post a drawing of your garden, with a few relevant photos (not mandatory, but it helps), we will be very glad to help you with your installation.

[felix]

Hi Veritas,

I think we are a few, possibly many, to read English, so please go ahead, we will do our best to help.

[veritas]

Thanks to both JPM and F for my welcome, particularly for being understanding of my failure with the French language. A language conditions the way we use our brains and imprints characteristics on them. I often wonder if starting with English imprints an inability to learn other languages. Perhaps we are just lazy or stupid?

Eventually, I will offer a detailed garden plan and photos because I will need expertise in excess of any of the local robot retailer installers have been able to develop. I recognise this skill comes will application practice which is completely missing in UK. The Husqvarna network within 100 kilometres of me has only experience with one customer and the Etesia network has none.

Finally JPM, I recognise that 1000 sq meters may be underutilising the Belrobotics/Etesia range because their smallest machine (Greenmow or Etesia ET44) is offered as being capable of 5000 sq meters. Area capability is only one of many characteristics that I would like to use as the selection criteria and I am not averse to the machine having too much in this respect. I would like to take into account quality of cut grass, reliability, support from retailer and manufacturer and the aspect that will be most difficult to assess, namely the ability to deal with complex and narrow garden shapes. Of course, cost of acquisition and installation will play a part in the decision as well.

I was wondering if the three-wire boundary system, which seems to be unique to Belrobotics/Etesia, improved the ability to deal with complex shapes or offered more control in regard to other aspects.

I get more excited about the robotic approach every time I read on your forum of some creative solution to what looked like a problem that could not be overcome. I will have many of these with a garden where the inner part is surrounded by a moat with water, where it is split into two by gates to keep deer out of the inner area and there is a gravel car drive and path splitting the outer area into 4 pieces.

I must find a way to insert diagrams (or attach files?) into forum postings. I could not find a way to do with my opening post. This was not a photograph image but a wiring diagram selected from a Belrobotics pdf file using the Take a Snapshot facility offered in pdf files. The diagram was quite happy to be planted into a Microsoft Word file but not into the forum. I have tried the windows "printscreen" method recommended but cannot find a way to paste this into the forum.

Any suggestions on how to do insertions that are not words would be welcome.

[JPMalef]

Here is the way we do it, the layout is now different, but it works. _o_

[URL http://automower-fans.les-forums.com/topic/33/comment-mettre-une-image-dans-un-message/]

[veritas]

Hello JPM.

Many hours of struggle with the process, so here it is, hopefully. This has been prepared by drawing over the Government Mapping Agency plan we used when building another part of our house. I mention this to give credibility to the scale shown on this map.

Your can see the inner garden surrounded by the blue moat. My estimate for the green area here is about 725 sq meters. The green shaded parts are where we cut now with the handmower. The inner garden is separated from the outer with gtes to keep the deer out of the inner area.

[URL=http://www.hostingpics.net/viewer.php?id=265829RoboticLawnmowerPlan3.jpg][IMG]http://img11.hostingpics.net/pics/265829RoboticLawnmowerPlan3.jpg[/IMG][/URL]

[JPMalef]

The only word coming to my mind is "challenging". The reason: all those long and narrow corridors. But, how narrow are they?
For big surfaces, it's perfectly manageable.

What do you mean with: "The inner garden is separated from the outer with [b] gtes[/b]"?

I think we will have to study this challenge step by step.

Let's start with: what part of the green shaded surface do you want to automate with the robot ?

[veritas]

JMP,

I never thought it would be easy and assumed there would be areas left over which were inaccessible to either robots or their ride-on alternatives.

I agree with the step-by-step approach. Here are some key thoughts that might be useful to the big picture.

I started thinking I’d like all the green areas to be mowed robotically (is that what you mean by PLC?) and after some study of your forum cases began to get excited that most of it might all be done with one mower from one base station. This would have been an ideal solution, but I recognise there will be factors that will leave a need for handwork to complete the whole green areas.

This gets us to some software in your forum site that tries to correct what I write. It is quite funny in this case, because I made a typing error and posted the word you ask about as “gtes” instead of “gates” but the forum software modified it to “gites”. I know this means something entirely different from “gate” in the French language and can understand why you are confused.

I call the “inner garden” as the portion bounded by the blue water on the north, east, south and part of the west side. The rest of the west side is solidly connected to the outer garden with land and this presents us with a deer and rabbit ingress problem. We solve this problem with a paling fence and two gates with wire netting on them that are normally closed unless we need to go back and forward. These are on the black line that completes the outer rectangle of the moat.

I think our need for “inner garden” closure to deer and rabbits destroys any hope of a one mower/one base system because the mower could not get out. So we may be heading to a one mower/ two bases system or a two mower/two bases system. Electric supply is available from the house and from the small building immediately to the left of the entrance from the road.

To help clarify what you call “long and narrow corridors” I am including two photographs here.

[URL=http://www.hostingpics.net/viewer.php?id=805564MG1692.jpg][IMG]http://img15.hostingpics.net/pics/805564MG1692.jpg[/IMG][/URL]

The first shot was taken from the very top point of the site map looking south towards the house and you can see the cut grass sward bordering the flowerbed above the longer grass of the moat bank. This varies in width but at its narrowest point is only about 60cms. More importantly, it is not horizontal land here because it has begun to slope down towards the steeper part of the bank of the moat. Am I correct in thinking that robot cutting here is quite impossible?

[URL=http://www.hostingpics.net/viewer.php?id=735863MG1714.jpg][IMG]http://img15.hostingpics.net/pics/735863MG1714.jpg[/IMG][/URL]

The second shot is taken from the top of our house chimney looking north towards these “long and narrow corridors” in the inner garden. This shows the corridor between the two flower beds. This is horizontal but is only 85cm to 90cm wide along its 20meter length. If this corridor must also be excluded it is not too much of a disaster because this will serve as the return path for the walk-behind mower needed to cut the outer corridor above.

The ride-on alternative would not tackle either of these corridors.

[JPMalef]

OK, let's start with the inner garden first.

We have to put (hide) the base station close to the house (electricity) and we have the choice between the left or the right side of the entrance pathway. But probably the left side of the house will be the best place

Could you post a picture made from the entrance gate, close to the house?

For the deer and rabbits issue, am I right that it is mainly during the night?

[felix]

This is really interesting and challenging! I am curious to see what JPMalef will come up with!
Just a thought, that I am pretty sure he already had, but just in case: with the rabbit's presence shouldn't we put the wring underground, protected in a duct, so that they don't bite the wires ?

[veritas]

Sorry for the delay, I have been away for a few days (not at the meeting in Davos, unfortunately).

Yes, the deer problem is only at night, but the rabbit problem is both night and day.

Your request for the base station location to be identified has caused some debate here, but I have selected a place for the base shown now shown on the site plan at A.

[URL=http://www.hostingpics.net/viewer.php?id=868138RobotLawnmowerPlan5.jpg][IMG]http://img15.hostingpics.net/pics/868138RobotLawnmowerPlan5.jpg[/IMG][/URL]

We do not think it would be an acceptable appearance to have it visible as you approach the house. We go to great lengths to keep our old house and garden looking traditional. So the base ought to be placed in a hidden spot. That rules out the right side of the footpath.

Security from theft is not an issue anywhere in the inner garden (or the outer garden for that matter).

You may know of ways of running high voltage from the house through the garden to an underground chamber sufficiently waterproof to house the transformer, but we are assuming for now that the transformer would be in the dry of the house and then the low voltage output cable can be run out under or through garden to the site selected for the base.

This would be conditional on a guarantee that the transformer would never be noisy because it would be in our kitchen. I think some types of transformer can develop a buzz as they age. If there was a risk of this it would have to be housed outside in the garden.

Do you know if there is such a buzzing risk with the Husquvarna transformers?

[URL=http://www.hostingpics.net/viewer.php?id=770999MG1830.jpg][IMG]http://img15.hostingpics.net/pics/770999MG1830.jpg[/IMG][/URL]

I have taken the picture you requested of the area to the left of the path, taken from the gate, looking towards the house. To begin with there is a very narrow part between the path and the steep moat bank. After this the ground rises as steeply as 30 degrees (58%) over a few meters and then we get to the honeysuckle bush in the centre of the picture that is more of less level with the rest of the garden. I would be happy to house the base out of sight at ground level within this bush and partly hidden by it. The obvious place is on the east side of the bush with the exit centre line pointing towards the two kidney-shaped red flowerbeds.


Can I turn your mind to how near to the moat edges we could hope to lay the boundary wire. I expect we will need to compromise here, leaving an uncut width for the robot to be able to stop in if we got a power cut, for example. The moat banks rise very steeply from the water (60 degrees to horizontal) and we would continue to cut these twice a year with a strimmer. At the top of the bank there is a slight slope, say 10 degrees to horizontal, before the horizontal table is reached.

[URL=http://www.hostingpics.net/viewer.php?id=445147MG1724.jpg][IMG]http://img15.hostingpics.net/pics/445147MG1724.jpg[/IMG][/URL]

We like to keep the grass short in this area as it tumbles form sight to look like a sharp edge from a distance and ideally we would like the robot to cut as near to the edge as possible leaving just a strimmer to tidy up the uncut portion rather than to require the width or two of a lawnmower. This may be asking too much.

The trouble is the every time we define an area that the robot cannot be expected to cover, there is more handwork and less justification for the investment of a robot. I cannot think how any small edging fence or catching device just before the edge could be configured so as not interfere unacceptably with appearance or ease of maintenance.

[JPMalef]

Sorry, I couldn't meet you in Davos, me be next time. BD

For your preferred place (A), reed this[url=http://automower-fans.les-forums.com/topic/1639/un-abri-pour-le-robot-astuce-jpmalef-base-en-re/?m=32#m18943] [b][t 3]here[/t][/b][/URL]

I have no knowledge about interférences between high voltage current and Husqvarna transformer, but by lack of information, what is your high voltage level, the distance from (A) spot ?
The low voltage cable between the Husqvarna transformer and the charging base is now 10 metres (for 3xx), but you can order a 20 meters cable as an accessory (option).

Now, let it put simple. Your moat, is for me like a sweeming pool. There is a very small risk that under some random circumstances, a software bug may lead to a flop (plouf) in the wather. _o_
I don't think there is a robot vendor that will guarantee there is no problem. In other words, protect your robot from falling in the water.

So, let's go ahead with a realistic approach. Concentration on the inner garden, no risk (no fun) approach.

Nevertheless, you mention: "After this the ground rises as steeply as 30 degrees (58%) over a few meters". Due to the documented limitations of the robot, are you sure you're not asking too much?

[veritas]

UK electricity is 230volts AC running at 50Hz, just like yours.

Spot A is only about 5 meters away from the power source inside the house.

One random event that will happen is a power cut, either because the mains supply fails or our internal circuit breaker trips to safeguard us. This sometimes happens when a lightbulb fails.

So with no current flowing through the boundary wire and the robot retaining power from its own battery, what happens? There must be a failsafe, but how long does it take to deploy? and how far will the robot have travelled by then? This might dictate how far the wire must be placed from the moat edge if we cannot (or do not wish to) build some barrier.

Would the robot be a total loss if it fell in the water and was left there for many hours?

[JPMalef]

When the main power goes off, the robot stops immediately, because he lost his magnetic field, and will wait till power comes back.
The only thing is that if the power is out for a week, the battery will be empty, and you will have to find the robot by yourself to bring it back to his station.

Concerning water, electronic under current don't like humidity, causing damage, no matter how long it stays. This robot resist rain without any problems, but don't like swimming.

[veritas]

Perhaps my thoughts are being misled by the colouring in the site tutorial,

[URL=http://www.hostingpics.net/viewer.php?id=557302peripherique.jpg][IMG]http://img11.hostingpics.net/pics/557302peripherique.jpg[/IMG][/URL]

but it looks to me that the magnetic field is only present near to the boundary wires. In the centre of an application, far away from the boundary wire, there appears to be no magnetic filed to influence the robot and this is no doubt why it does not change direction when it is far enough away from the boundary.

So, for an active robot positioned far away from the wire when the power cut happens, how does the robot differentiate between just being far away from the wire with the power still on as normal and the condition of there being a genuine power cut?

The clue may possibly be in the field strength graph below the coloured diagram where there is still a very low level of field far away from the boundary wire and perhaps the robot can differentiate between this very low level and the zero-strength field that would present if the mains power were cut off.

Is there any recommendation when you install the single strand boundary wire that all parts of the enclosed areas must be a minimum of X meters away form the boundary wire? I guess that even if there were no such recommendation, a maximum periphery would offer the same assurance.

And maybe this is a clue to the question where I entered this forum wondering why a three strand boundary wire was used by Belrobotics. Perhaps three strands are needed to ensure some magnetic field in every part when covering the very large 20,000 square meters area of their capability.

Has anyone ever heard of the electromagnetic field from robotic mower installations affecting the way that other sensitive electronically controlled devices react? I am thinking of things like drive-by-wire controls on car engines, for example. In my site, the whole house may become wired in an island to protect the flower borders around it from being mowed. Could my internet reception arriving in underground telephone cable become affected?

[JPMalef]

Yes, there is a limitation in the distance between the robot and the peripheral wire. The robot must stay within 35 meters distance from the peripheral (15 meters for the 305/308).
This means also that the robot senses the magnetic field everywhere within the peripheral.

Concerning influence from/to others systems/magnetic field, there is a known problem with some brand of dog electronic collars and containment systems (Petsafe). And one case of a robot disturbed by an electrical guitare BD.
Concerning your WiFi installation, no problem at all, I have a WiFi camera at about 2 meters from the base and everything works find.

[veritas]

I was not thinking so much of interference between router and any local Wifi device but more from the telephone exchange to my router.

My fragile internet connection is delivered through the copper telephone wires that come from the telephone exchange some 6 kms away. The last 2 kms run underground and end up running under the garden to connect to the house. Like many country dwellers this length of line offers a low strength signal with lots of noise to cause further reduction. If the signal dips too low the router becomes disconnected.

Sources of noise, I am told by our internet supplier, include electromagnetic interference from equipment that ordinary people would never think of, for example street lighting being switched on. I used to get disconnected every day at around 4.00am and the reason (excuse?) given was that some person far from here but near to our connection path must be switching something that offered an electromagnetic spike to the mix.

Oh dear, another minus to robotic mowing compared to ride-ons. The trouble with some of these risks is that it requires an installation to find out, by which time, it is too late to turn back.

It is still good to continue, however, and I am grateful to this forum. Without this discussion I would never have considered half of the risks identified so far.

[JPMalef]

I was referring to my WiFi camera to explain that the installation is not generating any disturbance to it. But it seems that your copper connection is from another age.

And the best way to know is to try. You will have to buy your robot from some reseller, right? They have usually a demonstration kit that could be use at your place to check if it generates trouble to your copper connection. If you know the location of this underground connection, put the base and a small peripheral (strong signal) just above and run a few speedtest. You will have to compare the results with an average mesure done before the test to verify any noticeable degradation.

[veritas]

I agree with you about copper telephone wires being from another age. They were put there for a completely different purpose from delivering the internet. We ought to have fibre connections for the internet, but the chance of that technology ever reaching my house is almost zero. The internet hardware providers could never justify the investment. Town and city dwellers have a better chance.

Thanks for the tip of how best to test if there is detrimental effect to internet delivery from the magnetic field.

Are you going to recommend a layout for the wiring and a robot?

I was thinking that with the inner garden, about 700 sq meters, being considered as the first system, a single 308 would be suitable and if we managed to have an outer garden system as well then another 308 would be a good idea on the same grounds as many other forum members express (because they feel vulnerable to just one larger mower).

One concern is that Husqvarna do not yet offer the 308 in the UK. The only third generation Husqvarna machine they offer here is the 305, which is too small for the inner garden area.

[JPMalef]

I am very surprised about your perception of Husqvarna in UK. My sheep was made in UK. BD

Have a look at this: [url http://www.husqvarna.com/uk/dealers/dealer-locator/]

Now, about which model is suitable for your inner garden? The 308 will be on the job for about 21 hours/day (recharging battery included), every day of the week. It can rest the weekend. The 320 will do the same in 8 hours.
The 220 model is still available, for a good price, and spare parts are available for many years to come.

Concerning the layout of the wiring, it would be nice if I could have a larger scale drawing of your inner garden. In the mean time, here is my drawing. Apologies for the look, tablet plus finger.

[URL=https://imageshack.com/i/5nzl9ej][IMG]http://imagizer.imageshack.us/v2/640x480q90/203/zl9e.jpg[/IMG][/URL]