Guide Wire??

[waxo]

Hi, I'm new to this forum but I builded my own RoboCut with Basic Stamp Microcontroller for about 12 years ago. The mechanical construction used by Ardomower is identical to the 12 year old Robocut. One of the biggest problem has always been to find the charger and tot loose its way before the bateries are drained. Husqvarna Automower use different ways of solving this problem GPS, Radio and guidewires in different combinations. Now you also get te possibility to make differnet areas to work on, lets say in front of house every day cutting but bwhind every second day.

GPS, Radio, Camera and so on maybe atract some of you but I think it's overkill and Guidewires are a cheap and simple solution of navigating.

Have anyone of you tested software modification for 1-3 guide wires?

Best regards, and stay relaxed when cutting your grass.
WAXO

 

[waxo]

Isn´t there anybody out there that have don some work here? I read a n old post from "alteschwede" where he had almost the same questions, but no answeres. So I have don some investigations on one of the top line products from Husqvarna, the Automoower 330X. It seems that Husqvarna not only hav one signal they have a lot to make the navigation work. Here are som information about the 330X, all in german.
1.6 Steuersignale des Schleifensystems.
Das Schleifensystem umfasst ein Begrenzungs- und
Suchkabel, die mit der Ladestation verbunden sind.
Zusammen arbeiten sie im Wesentlichen mit vier
verschiedenen Signalen:
• A-Signal
• F-Signal
• N-Signal
• Der 320 verfügt über ein Suchkabel. An dem
330X kann optional noch ein zweites Suchkabel
angeschlossen werden.
Siehe Kapitel 2.3 Menü Werkzeuge auf Seite 20 um das
A-, F- und Suchkabel-Signal zu überprüfen
• A-Signal
Signal, das die Ladestation in die Schleife sendet und das den Arbeitsbereich des Mähroboters abgrenzt. Kodierte Informationen werden
über das A-Signal zum Mäher gesendet. Wenn
kein A-Signal vorliegt, z. B. bei einer Unterbrechung der Begrenzungsschleife oder der
Stromversorgung zur Ladestation, bleibt der
Mähroboter stehen und zeigt die Fehlermeldung Kein Schleifensignal an.
• F-Signal
Fernsignal von der Ladestation, das von einer
Schleife in der Platine der Ladestation erzeugt
wird. Das F-Signal wird verwendet, damit der
Mähroboter weiß, dass er sich in der Nähe der
Ladestation befindet.
In seltenen Fällen kann es sinnvoll sein, den
Bereich der Ladestation zu reduzieren. Dies
kann erforderlich sein, wenn die Ladestation
z. B. nah an einem Busch oder einer Wand
aufgestellt wurde. Dies hindert den Mähroboter
daran an der Ladestation anzudocken, obwohl
er das Signal der Ladestation empfangen kann.
Die Einstellung lässt sich über Installation -
Finde Ladestation - Ladegerät vornehmen.
Folgende Bereiche gelten für jede Einstellung.
Einstellung Bereich
Min. 0 m
Mittel ca. 3 bis 4 m
Max. ca. 6 bis 8 m
• N-Signal
Das Nah-Signal der Ladestation reicht ungefähr
1 Meter. Das Signal wird von einer Schleife in
der Platine der Ladestation erzeugt. Das
N-Signal führt den Automower® korrekt in die
Ladestation hinein, so dass die Ladekontakte
des Mähers und der Ladestation sich berühren.

My experiens are that it´s very easy to have the robot to cut the grass. But to leave home for some days and come home and see the robot still working and not get stuck with drained batteries are very hard. But it can all be done with little hardware and most of it some smart software.

Best regards, tchüss WAXO

 

[roland]

With the standard solution of Azurite and Raindancer this is not possible.
The reason for this is, that the signal is send continously on the perimeter.
To use more signals, you need to multiplex the signals on different wires (with the same GND).
The current used algorithm can not handle this and the Arduion DUE is not the right platform to do this.

I am currently one step further. I developed an advanced perimeter receiver based on the STM32 Nuclo 446RE board.
Here I am able recognize a 5ms signal with round about 50ms pause in between.
It could be possible to multiplex a second signal on a second line and then recognize it
or use a second receiver for receiving the second signal.
The receiver is working. It has an I2C interface. But I have to build it in my robot to test for stability.

 

[waxo]

Thanks, at last someone more working on this essential problem. If the robot not can find the charger the grass won´t be cut as simple as that. I looked on the signals on two existing systems the Husqvarna Automover and a G-Force model. It seems that the use a similar system with coded perimetric signals and more like strong ping signals for guiding. Maybee it's poosible to use split recivers with multiple arduino nano for decoding and the bigger arduino for calculating. I have som ocilloscope pictures on the signals here.

I also have another idea abbout only use part of a repeated code to navigate. One reciver but multiple transmitter. Lets say you sens code 1 1 -1 -1 1 -1 -1 1 -1. You use the most significant bits for the perimeter 1 1 -1 -1 1 and then you add the least significant bits for the different guide wires. And the reciver have software priorites control.

But there must be a reason that the market leader Husqvarna use the "PING" and a combined code system.

Another system can be a raspberry pi with automatic camera recognition, but this is a compleatly different system I don´t manage today.
So the lawnmower will be smarter than me, and that is not good.

WAXO
Attachment: https://forum.ardumower.de/data/media/kunena/attachments/4856/HQautomowerPerimW1.png/

 

[bernard]

Using RFID tag on the perimeter wire and IMU is also a simple solution to help the mower Always find easily Station.
The ESP32 can also easily replace the Nano with a very fast readind signal.

 

[roland]

The real problem is noise. If you only use one ping, it could be that you are not able to distinguish it from noise.

As I heard, Husqvarna uses time between signals to determine the different signals. But I am not sure.
I am currently not able to interpret you pictures with different signal. I need some more explanation what signal is measured where an how did you measure it.
Really interesting is, how the signal looks like behind the receiving coil in parallel to the sender signal and how the frequency spectrum looks like and how the frequency spectrum looks like when the motors are running.

It looks like workx is not able to detect inside outside correctly. (at time 2:20) https://youtu.be/IxG-KUFOODc?t=139
The current used algorithm in Ardumower for perimeter recognition works very well. There are lot of things which can be done to make it better and make noise not so painful. Therefore I would not change the algorithm - only improve it.

One of the biggest problem has always been to find the charger and tot loose its way before the bateries are drained

I had never this problem with the Ardumower battery pack and the Raindancer firmware.

But to leave home for some days and come home and see the robot still working and not get stuck with drained batteries are very hard

That the mower get stuck could always be happen. Also if you use a Husqvarna. Therefore the undervoltageprotection is used in PCB1.3.
I only use the mower when I am home.

 

[bernard]

Hi Roland.
The video is very funny for a commercial mower (not for the buyer).
It's incredible how the motor work (1 year lifetime).
I have Robomow and Tianchen Mower and YES stuck is possible but if you put correctly the wire they work perfectly.
Professional put very ofen the wire at 80 cm of all border obstacle and without 90 deg angle, it's a good practice if you never want issue like in the video.

 

[waxo]

I have looked on the signals again. My guess is that Husqvarna have a very easy timeing software that works something like this.
First you have a rather complicated and coded perimetersignal. This identify that the robot are inside the right are to work, Here you need some prcessor power and a good algorithm for good detectinon,
If we say that the perimeter signal repeats every 1 second it makes more easy to explain and understand, later we can speed it up as much as the microcontroller allow.
The length and detection time of the perimeter signal is 0,1 second, then whe have 0,9 second to play with.
Lets say we want 3 different guiding signals. then we send A signal 0,3 s B signal 0,5 s and C signal 0,7 second. all that the software have to check is the time differense betwen the complicated perimetersignal and the simple ping signal from the guiding system. When everything works OK we speed it up 100 times or so.

What you think about this?

WAXMO

 

[roland]

Yes, that what I wanted to say with: "To use more signals, you need to multiplex the signals on different wires "
Because the main signal which tolds the robot it is in the working area must be good recognized, I use a 100bit signal.
The other signals must only be recognised, when the robot is over the wire. Therefor one could use the three Ardumower default 19bit signals if they don't correlate with my signal.