I’ve wound up here in search of info to help me along with a weed eater rover I’ve been working on.
I had plans of using the weed eater bot platform as a learning tool, that I could progress into something more refined/automated if it went well enough.
Seeing the amount of Ardupilot zeroturns here has sped up my ideas of project progression- and I wanted to ask some general questions to the group-
Please- take these as general Q’s. Yes, I can search, and have.
Autopilot method? What I gather, is a route is laid out in mission planner (or similar software?) - using the satellite images to “draw” around obstacles and leave space? Are these routes 100% drawn by hand? Are they easily saved/edited?
Accuracy? I get that this will vary based on components and setup quality- but what is a good range of deviation to expect? I.e, How close could one draw routes to fencelines or buildings without worry of collision?
RX/TX – One of my biggest hurdles with my current project was the range I needed. I started with wifi antennas, and bought a whole box full trying to get a setup to work well. I eventually abandoned this and went to a 4G setup- to be able to get anywhere near the 800-1000ft range I needed. It seems the main use is for telemetry in the mower setups, as there is not much use for a video feed- what ranges are you getting with your RX/TX setups?
Safety concerns – How do you handle run-away conditions? Is there a remote disarm that is readily accessible? Do you just sit and watch the mower incase a problem occurs? (My thought would be I could do trim work on one ZTR while the autonomous one works on the larger areas- a wireless pendant estop that I’d have with me is what I’m picturing)
Tuning- It seems the hardest part of these setups is getting them tuned to work well. One thing Ive learned the hard way, is that it seems there is alot of neat equipment available, but finding proper, solid documentation is difficult. Is there a list of Ardupilot parameters- with descriptions that I could study to aide me in feeling better about the tuning process? I won’t understand what a random parameter does if there is nothing explaining it.
Obstacle avoidance- I’ve seen mention of scripts, Lua specifically. I’m reasonable with C++ and to a lesser degree Python, Are there examples somewhere I can look into of how scripts interact with/in ardupilot? I’d like to get a feel of what I might be comfortable accomplishing there.
I use Mission Planner for making mowing routes and it does a very creditable job of it. However, you will have to make small corrections to get everything like you want. Incredibly powerful software but fairly steep learning curve initially. Once you understand it, very easy to mod and save missions.
For mowing anything other than a very small yard, you need RTK correction either local or over the Net. With that, centimeter accuracy is theoretically possible but your tuning likely wont be that good. I routinely run 2400’ lines with less than +/- 4” of wandering @ 5+ mph unless very bumpy. I plan to be within 2-4’ of any hard “edge” and then jump on the 72” Kubota for final trim work.
Using 100mW SIK radios, low loss coax, and good antennas I’m mowing out ~2500’ without issues and stable telemetry. Have no video on the mower.
My mowers can be killed via MP telemetry, RC controls or an Estop on the mower. They also have an onboard “crash” Lua script running looking for major incidents and I have the ignition relay wired to ground if power is lost to the Navigation System. After about 1200 hrs testing/mowing, I am comfortable with that. Others have a separate additional wireless kill system over the above. Really just what makes you comfortable. I seldom leave the property if one is running, but they have proven very reliable to date. The only time they have tried to climb a tree or found a ditch was because they were told to by the mission I loaded…
Tuning (and the documentation) has gotten much better for with latest firmware versions but will be the largest and most frustrating part of your project. With 840+ parameters to handle everything that flies, floats or drives, lots of opportunities to go astray. The parameter descriptions are not always helpful to folks without background knowledge but it’s learnable. Just plan on spending some quality time on this. It’s a very steep learning curve solo.
Active obstacle avoidance is the last big feature that our mowers need. Several of us have tried various options, but I don’t think anyone yet has a reliable mower system working. Onward!
I’m slowly getting up to speed as I dredge through posts here, but the direct questions really help.
I noticed mention of RTK base setups needing a line of sight to the rover. Do most use a “permanent” base station/antenna mounted to a garage- or wherever your PC is? This seems to head me back in the direction I started, of trying to get radio signals to work for my current rover setup. I was close to setting up an external antenna on my garage, but decided to try the 4G wifi route instead first.
About the tuning and parameters, Sounds like this is what I’m already working with in mission planner then? Thats good to know, I’ll see if I can find a list of parameters with function details- it would surely benefit me now- even though I’m not working with autonomous movements yet.
Most of us send RTK corrections thru the MP telemetry link (which is the easiest way) using little 100mW SIK 915 mHz radios. These are regarded as “line of sight” frequencies and power levels but easily work out to several thousand feet thru houses and trees with good antennas. Several guys are experimenting with high powered WiFi for extra bandwidth getting good results. I’m not there yet.
I have an RTK base here which MP can use directly or MP can pull my info from RTK2GO.com over the net. (We have several mowers in the area and others can use my info if their RTK site goes down).
Best way to learn the parameters is to get a mower working and march thru the Ardurover set-up docs step-by-step. Don’t skip ANYTHING. Once you have movement, start wearing paths in your lawn making small changes. Unless you have a UAV background, you have hours of learning ahead but it’s a blast to finally make it useful! Good luck!
Appreciate the answers. Seems its pretty slow here, maybe everyone is just out mowing..
I’ll continue searching the available info. I’m thinking I might buy one of the Ardusimple GPS boards to be able to do some generic autonomous setup on my current bot. Then when I start on a mower, I’ll have one of the needed boards already on hand.
marblecreek
(Rover; AP 4.6.0-BETA, Pixhawk 6X CM4)
6
I built my rig on the bench first. @Swebre2023 and @SJohnson helped me quite a bit. When I returned home, I mounted my servos and started tuning. Really - follow the first time setup and you’ll be well along the way.
Re the slow statement, I think you’ll find tons of help, IF, you do your homework first and then post your questions. Don’t make the experts ask for a log or comfig file. Put it in the question post.
I started a post on my build that others followed and chimed in when I went down a rat hole. Consider that approach and include lots of pics!
Don’t over look the Ardupilot Documentation that really lays out the details of how to build a Rover. It is very good documentation and our mowers are just a type of Rover.