Really interested to see how you set up your servos on the mower. I used linear actuators last summer, the response time was way to slow on the hardware. I have the mower (grasshopper 42") in the shop and am working on doing an engine swap and adding servos.
Vincent! Great to hear, manā¦ Iām still using a cheap compass and, of course, not getting very good results, but still getting the job done. I may try a RM3100 (eventually going to try moving Base, but will probably be a while). So, where do you have the compass mounted on your mower?
Kenny
I had a scary flyaway moment yesterday but a steep slope kept the rover in check. I think the speed controller glitched but I am not certain. EKF was good, vibrations didnāt have any clipping, and GPS had RTK Fix. Yet the rover drove past its waypoint and didnāt respond to a DISARM although it did register with the FC. I would like to put a failsafe on it that would recognize when the rover was moving away from a waypoint for a number of cycles and kill the drive system. This situation could happen whenever the steering control mechanisms fail. I do have a drive system kill on an RC channel/switch that did bring the rover to a stop.
I have had similar. Most recently, I had my Pixhawk reboot during a mission. Until it finished rebooting, the mower maintained the throttle positions it had just prior to the reboot. I have the same kind of external kill switch, but want to automate this to some degree.
I have signed up two computer science college students from a local university to āworkā for me this summer on an unpaid internship to develop a program on a co-processor (likely a Raspberry Pi for now) that will monitor location from the GPS independently of the autopilot and kill the mower if it goes outside a geofence. I am still developing the specification of what I want and it will evolve.
Anyway, I will gladly share anything we get done.
Iāve been thinking about this for a while. I donāt have much lawn to mow but it is on steep incline. In addition to flyaways, I am concerned about a roll over. So Iād want to kill the engine if pitch exceeds x or if if roll exceeds y. Is there anyway to do this without a companion computer?
I have done a lot of work on Raspberry Pi. I have at least 6 of them running things around the house. I have seen my fair share of SD filesystem corruption from bad shutdowns. I think an Arduino might be a more stabile platform for a companion/watchdog computer. I have found a few projects here that have mavlink working over UART on Arduino. The Arduino could be programed to watch the mavlink for flight mode, gps status, waypoint progress, and orientation of the mower and throw the kill switch when things go sideways. @ktrussell Nothing is more powerful than CS majors put to task. I am excited to see what they come up with.
I would use scripting in ardupilot or perhaps even on my RC, but the assumption is that there is a failure of hardware or software control. The autopilot canāt be trusted. We have seen them reboot. The RC canāt be trusted. We seen them lose contact. So I need a second control system onboard to monitor everything and kill the power when unexpected things happen. I am working on this project https://github.com/bitdog-io/restraining-bolt. It is designed to be installed on a Teensy 4.1 https://imgur.com/gallery/AzPJn4e This is how the mower is working so far https://youtu.be/frFU9pNqIiI
I like your idea of using a Teensy for the reasons you stated. I have many of the same issues and goals as you I think. I will certainly share anything worthwhile that I or the students who are helping me develop.
I have been motivated by you and Kenny Trussell and I am starting to plan out my zero turn mower conversion and buy some hardware. So far I have been just reading and learning a massive amount from you guys who have been blazing the trail. The mower reliably being guided by GPS seems like the real key and hopefully the Ardusimple F9P GPS with the RM3100 compass is the way to go. Is yours still working well for you? I would also like to know where to get the compass and if it plugs directly into the Pixihawk.
I am new to blogging and I am not sure if I should my questions related to getting started on rounding up the equipment belong in this topic area or I should be on a different thread. My mower will be a Hustler 54 inch zero turn that I routinely plan to mow about 4-5 acres with out here in East Texas where the grass grows so fast you can almost see it growing. I have a background in electronics and I retired about 10 years ago. Now I am really looking forward to jumping back into a fun project.
As far as connecting to the Pixhawk, you may have to provide the RM3100 board with 3.3V power rather than the 5V that is available from the Pixhawk. Other than that, I think it does connect fine. Perhaps someone else more familiar will shed some light on that.
I look forward to hearing more from you and seeing pictures!!!
(I had a total knee replacement about 7 weeks ago and have not been very active on here and have done nothing with my mower. Iām looking forward to getting it back rolling soon!)
Kenny
Thanks for the information. I am confused because the RM3100 is often called a magnetometer. Is that the same as a compass for this application?
I think this project will take a while because of other time demands but I expect to be busy on it during the winter. It seems strange but one of the first things I am doing is modifying the mower deck to discharge out the back (much like the finish mowers I pull behind the tractor). It will require a bit of welding and general fabrication but it will make planning my mowing routes easier and it will not get clogged up as easy under the deck when mowing way overgrown grass. I did find out that the air/grass discharge ducting channels underneath also require changing.
The other thing I am going to be working on while I am ordering the general electronics is to install a fuel sensor in the fuel tank so I can have it display fuel level on the on the RC controller.
Before I start spending money, I plan on posting my list of electronics for feedback from you guys (people with way more experience than me).
Take care and a speedy recovery from your surgery.
I welcome your feedback. You guys are the experts and maybe you can help a newbie in the autonomous mower world stay out of trouble.
I have been reading and learning from the Ardupilot website/blogs for a while. Now it is time make something real happen and start engaging.
Yes, a magnetometer, defined as āan instrument used for measuring magnetic forces, especially the earthās magnetismā is what sends readings of the magnetic field in 3 dimensions. Inside Ardupilot, these are stored in variables named mX, mY and mZ (for compass #1) and the Ardupilot calculates its heading from them.
And as you probably have seen, getting a stable accurate reading is difficult on a large metal body with electromechanical devices and moving metal parts, aka a mower!
My experience:
