lilengi200
Posts: 1
Joined: Mon Oct 22, 2018 11:20 pm

Creating a Self driving Lawnmower

Mon Oct 22, 2018 11:40 pm

I am creating a self driving lawnmower and don't know what direction to start the coding.

I have a RPi3 that is now reading my compass(LSM303) and my GPS (Ultimate Breakout GPS by adafruit) .

i need them to do:
Location tracking (gps would be best for this)
Homing Course Correction (compass)
Boundaries Limits (??)

I want to use the gps for precise location and the compass to keep its course while reading the location from the gps.

Any resources/suggestions on how to approach this?

Side note: I have codes that read individual device but I need them to communicate with each other, if i didnt make myself clear :D

klricks
Posts: 6790
Joined: Sat Jan 12, 2013 3:01 am
Location: Grants Pass, OR, USA
Contact: Website

Re: Creating a Self driving Lawnmower

Tue Oct 23, 2018 3:05 am

lilengi200 wrote:
Mon Oct 22, 2018 11:40 pm
I am creating a self driving lawnmower and don't know what direction to start the coding.

I have a RPi3 that is now reading my compass(LSM303) and my GPS (Ultimate Breakout GPS by adafruit) .

i need them to do:
Location tracking (gps would be best for this)
Homing Course Correction (compass)
Boundaries Limits (??)

I want to use the gps for precise location and the compass to keep its course while reading the location from the gps.

Any resources/suggestions on how to approach this?

Side note: I have codes that read individual device but I need them to communicate with each other, if i didnt make myself clear :D
Before you begin are you sure that GPS can give the required accuracy ?
GPS on my phone right now is showing 5m but jumps around up to 15m. (12 sats in view).
The theoretical best I believe is about 4m.
With that kind of accuracy a mower could easily miss my entire yard... Mow down the rose bushes and drive into my house down the hall to the kitchen.......
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

User avatar
Imperf3kt
Posts: 3233
Joined: Tue Jun 20, 2017 12:16 am
Location: Australia

Re: Creating a Self driving Lawnmower

Tue Oct 23, 2018 3:10 am

This may give you some ideas.
https://hackaday.com/2017/03/01/where-a ... awnmowers/

Also keep in mind that some countries have various laws regarding lawn mowers. IIRC, the most important one was that the cutting device must not exceed 19000feet per minute at its tip, which equals about 3000RPM for a ~24inch blade

This is for safety reasons, the blades may shatter themselves or debris could pierce the frame, injuring you or nearby people or property.

https://www.google.com.au/url?sa=t&sour ... iCFL_ut-Xv
Last edited by Imperf3kt on Tue Oct 23, 2018 3:35 am, edited 2 times in total.
55:55:44:44:4C
52:4C:52:42:41

User avatar
Joel_Mckay
Posts: 293
Joined: Mon Nov 12, 2012 10:22 pm
Contact: Website

Re: Creating a Self driving Lawnmower

Tue Oct 23, 2018 3:29 am

A practical api is fine:
https://www.mrpt.org/
Or the hilariously huge ROS framework if computing power is available.
;-)

Many warehouse robots simply use magnetic pickups from a signal-wire embedded in the ground, as it works as both a fence and location identifier.

Proximity doppler-radar modules are cheap now, and a good choice to safely halt the machine if pets/people get too close.
https://www.cnx-software.com/2016/04/04 ... way-for-2/

There are also surprisingly inexpensive front-ends these days that would work for a small platform.
https://www.acconeer.com/products

As others have already stated... GPS signals are weak and not really that reliable.
Make sure to add at least 2 emergency stop buttons.... ;-)
Best of luck,
J

sjm
Posts: 34
Joined: Mon Jan 07, 2013 12:53 pm

Re: Creating a Self driving Lawnmower

Tue Oct 30, 2018 9:25 am

There isa nother thread on this subject:
viewtopic.php?f=37&t=172960&p=1107117#p1107117

As I said in that thread I had a go at building a self navigating robot lawnmower. My lawn is surrounded mainly by patio so rather than any clever navigation I used a camera pointing downwards and opencv to detect whether the camera was looking at grass or not. If it was looking at grass it kept going, if it wasn't looking at grass it stopped, turned round a random amount and then set off again. Despite a less than uniformly coloured lawn and problems with shadows I got it working quite reliably...

ElEscalador
Posts: 778
Joined: Tue Dec 15, 2015 4:55 pm
Location: Detroit, MI USA
Contact: Website

Re: Creating a Self driving Lawnmower

Tue Oct 30, 2018 11:44 am

How intelligent are you hoping to make it? Bump and go good enough? As others have said - unless your yard is huge and you don't mind missing some by programming a large buffer, gps not accurate enough for the typical suburban home. Consider a buried wire like for an invisible dog fence. Next, see if you can get your compass working while near/attached anywhere to your lawnmower - especially while running. I have one on my small (hacked roomba) robot and placement is critical or it won't calibrate. Even then, if I drive past a toolbox of near a metal cabinet it becomes worthless (Even worse than worthless - it actually starts lying!) and I have to move the robot and wait for it to demagnetize then run calibration sequence again. For this reason I use it in certain conditions as a reference, but have a gyroscope as well. Not done with the code yet but hope between the two of them I can keep track of orientation.

What is the plan for obstacle avoidance? (especially dogs/kids)? I had always wanted to basically take every sensor and the brain/control board out of an older roomba and Frankenstein them onto a mower, but I live in a condo now and someone else mows my lawn.
Robotics tips, hacks, book extras https://youtube.com/c/practicalrobotics

User avatar
Defiant
Posts: 179
Joined: Tue Oct 30, 2012 6:17 pm
Location: Hamburg, Germany

Re: Creating a Self driving Lawnmower

Tue Oct 30, 2018 6:42 pm

I'm suprised nobody pasted a link to the ardumower project yet.

Return to “Automation, sensing and robotics”