Hi! Are you curious about wild new technologies? Have you ever wanted to build a robot — perhaps an autonomous large-scale lawn mower? If you are interested in these wonderfully fascinating machines that have revolutionized agriculture and are changing transportation, then I hope you will enjoy the project we will now undertake.
A Simple Proposition
Let us propose to build a self-driving lawn mower capable of following a pre-defined mowing path to within a few inches. Prospective applications for this mower might include sod farms, grass runways, interstate medians, and any other large area of grass that can be cut in a repeatable manner. We do not wish to build a mower for small yards — this is effectively a solved problem that is in a race to the pricing bottom.
Warnings & Disclaimers
Of course you know that this robot can kill you. We will spend considerable time discussing and implementing various safety tools, but we will not be able to create a robot that is 100% incapable of harm. The instructions given are for educational purposes only — we do not recommend that you build your own robot unless you are willing to take full responsibility for ensuring that your robot does not harm anyone.
Special Acknowledgements
If this project proves to be of any significance, it’s because of the help of profoundly good people who have instructed me along the way. First, of course, I must thank the Good Lord for everything. Next, let me acknowledge a few very special folks:
Beautiful Wife — Your encouragement has never failed. You’ve been faithful to the vows we exchanged eight years ago.
Wise Dad — Your brilliance in craftsmanship seems limitless. You’ve fought my bad ideas because you care. Now, as a father too, I understand.
Technical Acknowledgements
In the upcoming articles it will become clear that this project leans heavily on open-source technology. In particular, we will liberally use the work of a few folks who are remarkably talented. They are:
Until next time, keep on inventing my friends.
Peace,
Roby
9 Responses
Cool project! Looking forward to following it.
Thanks Golfman!
Nice and looking forward to see how it is going. If you get a chance we should def talk!
I started on this same path about a year ago (http://mr337.com/blog/robotic-mower/) and has the same issues with GNSS setup (http://mr337.com/blog/unmaned-robotic-mower-navigation-part-2/). In the end I needed something reliable so went with a commercial L1/L2 setup.
Here is where I am at today, https://youtu.be/uVTaHwCqPgw.
Lee,
Your progress is OUTSTANDING! Can you advise any specific prices you’ve heard for L1/L2 receivers?
Keep up the innovating, bro!
–Roby
Commercial L1/L2 isn’t cheap yet 🙁 My setup is 2 receivers (one base, one rover) with RTK @ 20Hz looking at $5k and that doesn’t include GNSS antennas, enclosures, interfaces, or the correction link which may be cellular or RF. If you want dual receiver for heading at 0 velocity you are looking at $5k for the receiver alone.
It is def not cheap, the best bet is the Swift in your RTK post, whenever that starts to support more than one constellation (GPS). Another option if you are around the $5k mark for a complete setup is RTKite, kit includes everything you need to get going including RF link (http://gnssrtkmodule.com/).
Hi Lee — That’s way too expensive. Check the RTK prices listed here: http://deepsouthrobotics.com/2017/04/20/spilling-the-beans-on-rtk/
$450-$900 Is the latest prices I’ve heard for good Chinese L1/L2 GPS/GNSS w/ RTK @ 10hz-20z.
Have you talked with ComNav or Unicore? Those guys are a disruptive force.
Hey man thanks for weighing in! I’m going to be creeping your blog — you better keep it updated!
–Roby
Have you worked out the lever controls for your mower at https://rplstoday.com/community/threads/finally-spilling-the-beans-on-rtk-gnss.330472/page-2 ?
I’m using https://www.pololu.com/product/2327 with the 12 amp controller and using code to drive the motor controller. Its not finished yet since I decided to re-mount the actuators, stopped to get RTK figured out and I’m bouncing back and forth between Pixhawk + Arduino or Navio2 as the controller.
Hi Al! We do have the lever controls worked out, and I plan a write up of that mower in the near future.
Regarding the Navio2, I’ll be interested to hear if you decide to use it — I haven’t used it, but have been tempted to buy it.
Things seem to have moved along since the last post here. I found this site when searching for „gnss mower“ since this is also my dream project. Since my development plan starts with a position aware moobile platform I had previously searched and found an affordable diy robot that moves about with the necessary precision: https://custom-build-robots.com/electronic/precise-gps-gnss-positioning-with-a-raspberry-pi-and-the-rtklib-introduction/8080?lang=en The author sems to have made an impressive rover that might easily be adapted for a mower. I will certainly try to copy his project to get the navigation buttoned up before moving on to the mower.