Perimeter wire is better than GPS RTK. (IndyMower #2)

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[rohankatreddy]

"When your new project kills the flowers, your mom kills you" Thats gold man

[kreature]

Professional systems use a +/- single cycle chirp with a specific repetition or a waveform with a skewed duty cycle. This allows it to detect not only if it approaches the wire but from which direction. When the mower moves outside the boundary the signal is inverted and by using a chirp or skewed duty it can detect this. It is not possible to distinguish phase skew from inversion with a symmetrical signal. With proper amplification this also allows the system to always detect the signal anywhere inside the boundary so it can stop if power is lost to the boundary.

[microdesigns]

I thought about this a long time. I felt that perimeter wires were great.
But to make different mowing patterns would require more wires.
And if the mowing area needed to change, the wires would need to be replaced.
GPS didn't seem accurate enough (at the time) and could glitch too easily.
The biggest drawback is the non-patterned mowing algorithm that wastes time and energy.
I settled on the idea of using a scanning head that looks for reflectors placed around the yard for triangulation. This is the method used in many factories for robotic forklifts.
But I don't have time to work on such projects because work keeps me busy, and family.

[awesomefacepalm]

I actually working in development for commercial robot mowers like that.
As a collision sensor you could use a magnet on the front bumper and a Hall-effect sensor to detect changes in the magnetic field.
With that you have a non-mechanic detection solution which means it's less likely to fail.
You can also use it to detect if someone lifts the mower.

[mslonik]

Imponujące. Trafiłem na Pana stronę przez czysty przypadek. Jest Pan przedstawicielem coraz mniej licznej grupy osób na YouTube, które nadal czerpią radość i satysfakcję z tworzenia i dzielenia się swoimi dokonaniami z innymi. Dziękuję!

Co do tego konkretnego projektu: jedną z zasad „skutecznego koszenia” jest możliwe ścisłe przyleganie obudowy ostrza kosiarki do podłoża. Dzięki temu pod obudową powstaje minimalne podciśnienie dzięki obracającemu się ostrzu kosiarki, które przypomina śmigło. To podciśnienie sprzyja pionowemu ustawianiu się źdźbeł trawy. To z kolei ułatwia ostrzu równe ścinanie.

Zastanawiam się, czy pomyślał Pan o adaptacji jednej z dostępnych w sklepach dyskontowych taniej kosiarki elektrycznej. Częściowo znalazłem odpowiedź w samym filmie: chodzi o projekt, który można będzie w pełni zrealizować samemu. Może jednak na etapie przygotowania prototypu miałoby to sens?

Czekam na kolejne projekty open source / open hardware. Na przykład na pralkę.

Serdecznie pozdrawiam.

[SianaGearz]

3:00 When you're trying to sense a signal of particular frequency, you terminate that inductor with a capacitor to create a tuned oscillator. Just use some random internet LC calculator to come up with the values.

Safety feature suggestion: continuity detection for the perimeter wire.

NRF24L01 is OK but keep in mind possibility of ESPnow, which is a similar thing but it communicates between ESP32/ESP8266 microcontrollers. I don't like shopping for NRF24L01 because there are a lot of fakes and their compatibility to each other including wireless protocol is very hit or miss, and the quality of the modules is as well. I haven't shopped for Nordic microcontrollers in a while but when i last checked they were on the expensive side as well, if you wanted to have radio and microcontroller on the same IC, which i find myself usually wanting that if possible.

I wonder if there's some sort of base station triangulation system one can build cheaply. I would like everyone's suggestions, is sure to come in handy someday.

[MisterMakerNL]

I can see you are still a beginner engineer your desk is still way to clean.

[Realmaker]

Even if it is not for this project: For RTK you could have a look at the Adafruit ZED-F9P and RTK SSR. SSR is using correction data that can be broadcast instead of per device corrections.

[solveit]

Hoho Metabo, powodzi się! 😂 Dobry sprzęt, piękny garaż z OSB, widać że przemyślany. Kibicuje od dawna, i chciałem powiedzieć że bardzo szanuję za mentalność open-source.

[ІгорАлієв]

Świetny projekt! Zrób wykrywacz metali na twojej wykaszarce. To samo wykryje siatki, słupki i metaliczne śmieci, który potrafią uszkodzić wykaszarkę. Z innej strony z detektorem metali wykaszarka sama potrafi omijać ogrodzenia i zmniejszy prace dla markowania miejsc, zabronionych dla niej.
Jeszcze dodaj żyroskop, żeby wykaszrka jezdziła wzdłóż linii równoległych i nie omijała części pola na dużych działkach.

[TheEragoon]

Base corrections over NTRIP are used by surveyors around the world, so don't think it could only be used on your local country. It works the same on every country, you insert the address (IP) username & password, port and (optional) mount point (basically if they have multiple receivers you can choose one). That's it, you now have the corrections. This requires an internet correction tho. But it can be used on many other rovers, even drones.

[DEADBF]

I mean RTK GPS *is* objectively better. It's just more expensive and needs a lot more work to implement.

If you have a large garden (1 acre+) then mowing randomly is super inefficient as a random path mower will be mowing some areas dozens of times while other areas might get mowed relatively infrequently (or not at all). Likewise if you have multiple smaller lawns and the mower needs to traverse areas to get to them ....with a boundary wire mower you basically need multiple mowers.

Due to the relative simplicity a boundary wire mower is probably the best place to start for a DIY project though. But I'd aim to make it as modular as possible, so folks can add RTK, Lidar, vision, etc if their lawn requires it and budget allows for it.

[jst]

1:30 Husqvarna uses guide wires (at least 2 up to 4) as well, this way can mower faster return to charging station, otherwise must mower do at least 1/2 (on the long run) of the boundary wire path.
On the other side, worx landroid (positec company) uses only boundary wire (for virtual fence and return path to charging station).

Both those mower have lift sensor in front wheels (if you lift front part while mower is moving, then should mower stop instantly & stop the blades spining as well ).

Wire, vs gps (+rtk station), vs lidar, the later is for all terrain.

[JaklizTheEngineer]

Seeing a video with such title appear, while I'm going to bed at 5am, after working on my thesis about RTK mowers is ... idk :D, my brain is shutting down, good night

[Sulybrainerz]

Mom be like 🩴🩴.
Don't destroy the flowers bro.

[jonathantribble]

What about using two sensors? One 45deg to the right of the front and another of the left. It could better detect corners and could tell which direction the wire is in. Keep up the great work!

[TheCreat]

For me personally, I'm not a fan of perimeter wire (only), because typically the robot doesn't know where it is, or what the shape of the area is that it is mowing. It can't plan a route or pattern to cover it efficiently or quickly, and it can't even be sure it got to it all. It's just statistically likely that it'll cover everything eventually (if the shape isn't too unsuitable), just by randomly bouncing off the edges. Of course this can be improved with other sensors (internal or external), but true absolute positioning would be in a different category. There are of course also ways to do absolute positioning just in a small area (multiple receivers triangulating it's position), but I do understand why that isn't and can't be the focus right now.

It's still great to see the whole process you use to design, even if the product or project isn't specifically "for me". Also it being open source means everyone can add whatever positioning system, or it'll be an option V2. Either way, great project!

[mbhh]

Glad to see you're do this project. I also built an autonomous mower for my engineering final year project. It looks rubbish but I was suprised with how well the perimeter wire worked. My hardware is very similar to yours though. I amplified the signal by 200 using an op amp and used two inductors angled at 45 degrees to the center plane on each side of the mower. This made it very easy to program which way the robot turns when it detects the wire. Also filtering the output from the op amp with a large capcitor made it much more readable for the arduino. I have a video on my channel with the contraption in action.

[grahamnichols]

I am really pleased to follow this project as I have been working on something similar using a commercial robot mower that I purchased on eBay. It had no charging base station, battery or working main PCB. But the BLDC motors work OK. Having no money for the expensive GPS RTK, the perimeter wire is my go-to. Can the plastic food containers withstand the UV and remain waterproof? Guess I'll find out the hard way. Have you considered using the JSN-SR20-Y1 ultrasonic detector module with car bumper-style ultrasonic weatherproof transceivers for potential collision detection? These are on my to-do list. Right now my main headache is efficient power management, as my motors are 18V and the electronics are 5V. Anyway, good luck with your progress!

[TheRainHarvester]

16:45 of the wheels slip on grass, it will still not go in a straight line. I don't know if it really needs to. Great progress!