I want to use pixhawk with the apm rover firmware to operate an agricultural tractor. I need to set up my tractor as an rc vehicle.  My plan is as follows: any feedback I can get is appreciated.  I plan to order the parts in the next couple days but if there is something I've overlooked or my plan has no chance of success let me know.

Throttle control: Linear servo (https://www.servocity.com/html/25_lbs__thrust_linear_actuator.html#...) I don't see too many problems here.

GPS: I plan to use the gps already installed in the tractor.  I am planning on buying a pololu 23201a to convert the serial nmea to something I can input to the pixhawk.

Steering: This is what I'm most worried about.  The tractor has an electric over hydraulic steering valve, so basically provide 12v to right side tractor turns right, provide 12v to left side tractor turns left. I am planning to put in a dual 12v relay controlled by pwm signals for the steering https://www.servocity.com/html/electronic_pwm_controlled_dual.html#...  Anybody have a gut feel on whether this will work or not?  The problem is the steering output from pixhawk needs to reach a certain threshold before steering valve will operate this is quite a bit differnt than how it is set up on my rc car where each pwm value corresponds to a specific steering angle.

Clutch: Much testing has to be done with a person in the cab to operate the clutch and some sort of ignition failsafe installed before I get the tractor to be totally autonomous but I would like to start thinking about the clutch, and start testing some setups with a person in the cab.  I could get a linear actuator that releases the clutch when throttle pwm reaches some predefined threshold? But I would really like a system that if the power is cut or signal is lost clutch is automatically depressed which will stop the vehicle. I could set the clutch up to be always depressed and use a linear actuator to engage it. Connect the actuator to the clutch with an electric solenoid so if power is lost actuator releases and clutch disengages. Anyone else have some good ideas?

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So I had a chance to show off my tractor to a group of 30 people yesterday as part of a crop tour.  20 farmers and 10 more from other areas of agriculture (banking, equipment sales, agronomists, ect.) It worked flawlessly again so that was good. I was really surprised by the amount of fear people had.  It took a fair amount of explanation on my part to get people to step out of their vehicles.  Most people planned to keep their vehicle in gear with their foot on the brake so they could make a quick getaway if necessary.  Part of it may be that I'm just some guy that doesn't have any formal qualifications or letters behind my name but most of it is deeper than that I think.  This wasn't a random group of people this was a marketing club of which I'm a member so these guys have been hearing about my tractor for a while now, and the group has a reputation for being on the leading edge of technology in ag so I really thought as a whole they would be very receptive to the idea.  The other reason I thought people wouldn't find this too big a leap is that we have had auto steer for 10-12 year now.  We have become so reliant on auto steer that most guys stop their equipment if the auto steer quits for any reason. I really thought the discussion afterwards would be along the lines of I can't wait till someone commercializes this so I can get it on my farm, but it was mostly a comparison of how this felt like the early days of auto steer when everyone was leary of the technology and found it completely crazy that someone would let a computer steer their tractor.  I'd say about 25% of the group was curious but not enthusiastic. 25% stated that they would never have an unmanned tractor on their farm, and the remaining 50% thought it was cool and could see the potential but were not going to be early adopters, they would wait until something commercial had been in use for many years before they thought about it.  I also got the feeling that people thought it lacked some credibility when I explained that it is all open source.  I thought people would be excited about the prospect of having some control over the tech in their tractor and being able to participate in its development.  Surprisingly I think people would have trusted it more and been more excited if it had been top secret tech developed by some large corporation. 

I'm sure none of the above comes as a surprise to people doing this kind of thing but I was surprised because there has been so much talk of autonomous cars in the news and I thought people would be more receptive to the idea of an autonomous tractor but apparently when it comes to autonomous vehicles society has a very long way to go before people are ready for widespread adoption of the technology.  A lot further than I thought at least.

Very interesting report. It doesn't surprise me that people are confused/wary of open source, but that's simply a function of regular users vs developers. (developers understand that the whole Internet runs on open source, but for regular users that's just plumbing and all they see are commercial interfaces such as iOS or Windows).

Our experience is that the way to get adoption of open source code is to put in a pretty box that just works. In our case, that's a drone or an autopilot, but in your case it might just be solid bit of industrial-looking packaging with a nice logo on it.  The nice thing about that is that it's easy to charge money for hardware, unlike software.

Entrepreneurial opportunity?

Entrepreneurial opportunity? Maybe.... I am going to make some significant changes over the winter to my existing system for myself, and then I don't know.  Working on this has been some of the most fun I've had in a long time but If I start selling something that might take the fun right out of it.  Someone is going to do this eventually whether it is with open source or some proprietary system but the first company to be successful at this on a large scale is going to be the company that can provide support on a large scale.  When work needs to happen on the farm and something doesn't work and a farmer cant get someone on the phone in 20minutes or less at any hour of the day, the $#!^ will hit the fan.  The upside is that farmers are willing to pay for that level of service.  At least they do with other gps related items, the cost of gps/autosteer systems is insane now that I understand the cost of the hardware so I assume most of the cost is an upfront service fee as most service calls are "free".

It's tough to think about doing something other than farming, the lifestyle and ability to make my own schedule is very appealing but we will see where things go.

I'm not too surprised that people were afraid of it, but I am surprised they were afraid enough to want to stay in their vehicles. Especially guys who know tractors. Maybe they too recently watched the movie kill dozer? Or maximum overdrive? I've showed your videos to a bunch of my friends who cash crop in western Ontario and we agreed it was a great achievement, and we wish we had the motivation to do it first. We are all mid 20s though, so that could make a big difference. Perhaps these guys just aren't comfortable with things they don't understand, and aren't willing to do the learning it takes to understand something like pixhawk

As someone who was on the receiving end of a bad accident at work a couple years ago, I tend to trust the machines more than most people would, because I recognize that the human operator is much more likely to behave unexpectedly, whereas the machine will do exactly what it is programmed to do. The risk of course being there is still a possibility of a hidden human error in the coding which is obviously not good.

In short, I think this type of thing will be way more accepted in a younger crowd
There is basically a prohibitive amount of liability in releasing a commercial product like this. Kinze and John Deere both have the technology for stuff like this. There's a Kinze autonomous grain cart on the youtubes somewhere, and John Deere has iTec pro. ITec pro is capable of taking full control of the tractor, and doing any repetitive task you can think of ( planting, tillage, spraying, etc) but they insist that you sit in the seat. In fact, they insist so strongly there is a safety switch in the seat that will stop the tractor if you stand up. Of course there were some guys on the internets who disabled or otherwise override this switch, and made a video of their tractor driving around with nobody in it. John Deere corporate was not at all pleased with this. And I think Kinze legal killed the grain cart, because it was years ago that they released videos of it, and I don't see it as a product yet. Both of these companies realized that if their product misbehaved in any way there could be serious repercussions and they'd be sued into the next century.

TL;DR: I think you're wise to hold off a bit before you start selling this. At least you should come up with a very, very good EULA.

As far as I know Kinze is still planning on a commercial launch of their system http://www.kinze.com/article.aspx?id=341  There is no doubt that autonomous vehicles are going to cause injury and death as they become more prevalent, the hope is that it is at a lower rate than human operated machines.  What we need are laws that take this into account and enough data for an insurance company to be able to provide a reasonable price on liability insurance, but before any of that is going to happen someone needs to go first.  I think all the major equipment manufacturers are standing on the precipice and looking to the others saying "You go first!" when your company is worth big $$ than some caution is understandable.  It's much more common in the mining industry so it's not like it isn't happening.

It will be very interesting to see how some of the liability safety issues get resolved over the coming years.  I am pretty sure we will have commercially available self driving tractors before we have self driving cars.  I'd even be willing to make a friendly wager on that if anyone wants to take the other side of the bet. What happens in ag with autonomous vehicles is likely where some of the legal stuff might get sorted out before it happens on the road.  What I'm not sure about is if I want to be involved in that.  I'm not concerned about the liability for monetary reasons,  but I'm not sure how I would live with myself if some programming error or hardware failure of something I sold killed or maimed someone.

At some point we (as a society) will have to decide on some basic safety standards for autonomous tractors, cars, ect that must be included on every vehicle, to provide manufacturers with some level of protection as in we know it isn't going to be 100% perfectly safe all the time but if A,B,C are included then we feel that you have done an adequate job of making it safe so that if some freak event occurs that causes death or injury you won't be held responsible.

Matthew: only some ideas to discuss:

Did you try Tower: follow me?

Isn't better for secure have a radio control too to control the tractor if something go bad with pc connection?

I think that in near future, almost here, this technology is going to be necesary to work in the farms because young people prefer to work in the city, no people to drive tractors. 

Success!!

I just got the first full day of harvest under my belt.  Cart worked great all day.  I have a video with the crop going into the combine and unloading into the grain cart but I'm too tired to post it tonight.  It's not much different than any of the latest videos except Im actually harvesting and unloading something.  I dumped a total of 20+ hoppers today.

Congratulations.  Amazing work on your part Matthew.  Very well done.

Thanks, Grant.

So here is a video of the tractor actually being useful.  Up to this point it has been a giant time suck, but it just put in it's first full day of work.  I see no reason why I wont use it all harvest without a driver.  Testing went so well that I didn't even bother to have someone in the tractor at all yesterday, not even for one run.  I was pretty sure I was wasting my time on this project so I am over the moon excited that it works as well as it does. I saved around $300 dollars in wages yesterday (more importantly I was able to redeploy the labor to other tasks), of the 80acres I harvested yesterday 20 of those was while I was actively unloading into the cart.

Thanks to everyone who has put time and energy into Pixhawk, Mavproxy, Mavlink, DroneAPI, MissionPlanner, APM Rover, and all the great documentation that goes along with those. I couldn't have done it without you! If you are ever in the area stop by for a drink! Sorry if I missed anything, or anyone.

In the video I mention that the tractor comes a little close to the combine and I attribute this to it being dusk (time of day when gps often does funny things) I am totally wrong about this being the cause of the problem, it is a thing though.  I swath my fields with autosteer and I always set the direction either EW or NS, East West in this case.  Then when I get to the field with the combine I can use the autosteer on the combine to follow the swath.  Because gps can vary a bit the combine has a feature called "nudge" basically if you see that the combine is drifting a bit you can nudge the autosteer right or left. I didn't have my combine set to exactly the same width as my swather so over the course of the day I kept nudging it in one direction as I moved across the field.  I clued in when I realized that I was having to move the grain cart the same amount away from the combine that the value of "nudge" had crept up too.  I can't believe it but I checked and rechecked this behavior and it seems that when you use the nudge feature on the combine autosteer it adds some offset to the gps coordinates and then outputs the modified coordinates through the nmea serial connection which I feed into my laptop that ultimately determines where the cart will be relative to the combine.  Now that I know this is how it works I can work around it but I think this has got to be a bug in the software in my combine, the nmea serial output should be the unadulterated gps position, at least in my opinion.

Congratulations Matthew!!!!! How envyyyy!!!!

How do you empty the cart to the truck? someone is waiting for it?

Awesome that it's working so well!

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