OpenMower

OpenMower copied to clipboard

Hi. I'm very interested in the project but It Is not clear how to start the hardware part. Which parts to buy, if It Is mandatory to have a dedicated PCB produced ecc

Yeah I too would be interested in a bit more detailed guide of what exactly needs to be purchased, which PCBs made, ...

I had a look at the BOM and it seems a bit incomplete - it seems to only cover the main board components, but doesn't include things like the GPS receiver, ...

Based on the video he posted, the gps receiver is a simplertk2b (with a zed-f9p GNSS module) and a u-blox multiband antenna. These are relatively cheap, around 200 euros, considering that other brands usually cost several thousand euros.

Maybe it's even cheaper to hook up an old smartphone.

@Kisses99 The problem is that your smartphone is not RTK compatible. You need a GNSS module that supports RTK, such as the ZED-F9P.

Ah got it. But it really stacked up the cost and made this build less attractive though.

Yes, the cost of RTK certainly is a barrier to entry. This was especially true before the ZED-F9P, where it was mostly reserved for the industry and extreme hobbyists. Another issue is that you might need 2 of them, where one acts as a base station, if there are no freely available base stations near you through i.e. RTK2GO and you don't want to pay for a commerical subscription

@Kisses99 there are cheaper optiins as well, but i guess they dont provide enough precission for a task like that. Did you ever check the precission of your smartphone gps? its most likely not below 5m...

Unless you use some sort of differential gnss (which RTK is a subgroup of), you can't expect better accuracy than 3-10 meters depending on the conditions. Compare that to RTK which has an accuracy of < 2 cm.

@FadeFx right that's what I just figured. However I'm still concerned that gps accuracy may be significantly impacted by shades of trees. For an open yard this may just be fine.

Yes, the tree shades and buildings is what I am concerned with. I have been working with this exact model during this spring and it often has troubles when you enter non-open areas

could it be possible to compensate this by also taking in account your actual movement? I mean from the motor controlls

You certainly can predict your movement using multiple sensors by a kalman filter. However, it might work to simply drive randomly when you are in a region without signal, since this is what they already do. The issue is of course the possible lack of boundary wire

Yes, the cost of RTK certainly is a barrier to entry. This was especially true before the ZED-F9P, where it was mostly reserved for the industry and extreme hobbyists. Another issue is that you might need 2 of them, where one acts as a base station, if there are no freely available base stations near you through i.e. RTK2GO and you don't want to pay for a commerical subscription

Is the German SAPOS system which provides Ntrip in RTCM 3.1 format what would be needed here?

@mischla Most network RTK providers which uses RTCM 3 should work, but you should check out which satellite constelletions they provide corrections for (GPS, Galileo, GLONASS...)

Thanks for the quick answer, in this case all of the mentioned. Link below in German valid for NRW: https://gppspro.saposnrw.de/service.php

Maybe a look at ardumower.de and it's Sunray (GPS-RTK) firmware might also help you https://github.com/Ardumower/Sunray

Hi, wouldn't some form of triangulation using bluetooth iBeacon be possible?

Hi, wouldn't some form of triangulation using bluetooth iBeacon be possible?

What is the accuracy you can achieve? Everything more than a few (more than 10cm) over the complete backyard is just not acceptable!

From what I could find on the Internet, the accuracy is at best one meter, which is not good enough to be used for control. Could maybe be used as a backup if you add a safety zone on 1 meter from the perimeter when you don't have RTK, but it will of course increase the price of the already pretty expensive build

Hi! Coming back to the initial question, would it be possible to add a "getting started" section to the readme? I have extensive software background and I tinker with some electronics, but I've never created my own PCB. Looking at the project, I have the same problem as @chicco83 - where to start?

Have a look at the wiki. Most of the needed infos are there... If in doubt, just ask in the discord

Thanks for pointing me that way! Here's the link for those still lost: https://wiki.openmower.de/index.php?title=Main_Page#How_to_Get_Started

Edit: also added a PR to add this info to the README: https://github.com/ClemensElflein/OpenMower/pull/29

There is a better guide now: https://openmower.de/docs/getting-started/