Hi All !
I have an aspirational goal to turn my kids ride-on car into an autonomous lawn mower! I’ve been tinkering with arduino and done other things, so i’m not a total nube… I’ve been reading lots of the ardupiliot guides and hardware options and researching rtk. I’m really excited about the ardusimple board, but before i dive in deep with the inve$tment i thought I’d start with a basic setup… I am new to ardupilot and pixhawk.
I’ve found all the parts I think i need to get going, but I’d love someone to check me out and let me know if I’m doing something dumb - or inexperienced. Here’s what I’m looking at:
David,
Welcome to autonomous Rover fun! More experienced folks can jump in behind me with more info and/or corrections, but I’ll try to help.
The ebay description and picture of the Pixhawk seems to indicate it includes a power module, so you may not need that item on your list.
There was an issue with the earliest Pixhawks in that only 1 MB of flash was accessible. Later versions could use 2 MB. I am still a little confused on the version numbers, but I think version 2 and higher is the one that could use 2 MB??? I may be wrong about version numbers and such. The one I am using looks just like the one you link to. AND, for $28 and a small RC car, you probably don’t need to worry about the memory. I bought this https://www.amazon.com/gp/product/B01N4KJEV4/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 (no longer available but similar ones are). The one you show on ebay looks to have about all the same accessories, except the GPS/compass module.
The telemetry radios you have for $20 will allow the Pixhawk running Ardurover to communicate to/from a PC running ground station software such as Mission Planner. That will let you upload missions, monitor the status of missions, set parameters, etc. It is pretty much essential.
For the RC Remote, from what I found doing a quick Google search, you may have to modify the PS2 controller to work with the Pixhawk. The Pixhawk has PWM inputs that connect to a standard RC receiver outputs. From what I gather, the PS2 controller does not have that?? In addition, modern RC receivers have SBUS which combines all the receiver channels into one signal cable so you don’t have to connect several individual PWM cables to the Pixhawk (the Pixhawk supports SBUS). So, my recommendation is to buy a “real” transmitter and receiver kit that is ready to go. I bought https://www.robotshop.com/en/radiolink-t8fb-24ghz-8ch-transmitter-r8eh-8ch-receiver.html for $49. It has worked very well. The range is about 1500 feet for me (which is basically what it is spec’d for). I am experimenting with a more expensive unit now for more range, but I have no complaints with the Radiolink I have used for months.
The NEO-M8N module you have appears to have a built-in compass (most do), which is good. So, I think you are good there. The NEO-M8N is probably the most widely used non-RTK GPS. I think you are smart to get your rover going with standard GPS before you open the door to more complexity with RTK.
I can’t help with the ESC. I have automated a zero-turn mower (https://www.youtube.com/playlist?list=PLIsYv3gzZOt9N9yZmpI_WYiMaBQ6HazOG) which has hydraulic motors, not electric. I glanced at your ESC, however, and see that it accepts PWM inputs, which is what you need, so it is likely fine, assuming the ride-on car doesn’t need more than 30 amps.
Again, welcome to the fun, sometimes frustrating, fun, rewarding, fun (did I say fun!) world of autonomous vehicles. It really is a blast to see your vehicle navigating autonomously.
I hope this helps some, and more experienced folk will come along and fix where I have misled!
You will find the support here among fellow users, many very, very experienced, to be exceptional.
Kenny
Hi David,
I’m working on my own autonomous mower too. First step I built the vehicle with RC-Control (see: https://youtu.be/tq1Olt-JtdU)
This mower works since 2 years on my own horse willow.
I use two 24V DC-Motors, both are controlled with two Pololu Motor-Controllers. These controllers are very easy to use, because you can connect them onto your RC-Receiver
Next step: Building stuff based on APM Controller (predecessor to Pixhawk PX4), GPS, Sonar, Lidar, …
Hi Kenny, Thank you so much for your reply and recommendations! Really really appreciate it! The RC control you provided looks like a good upgrade, but not as pricey.
This was confusing for me - do some versions of the Pixhawk have compass? Or does it always rely on the gps compass?
I’m excited to check out all your videos - looks like you’ve got some awesome stuff going on.
Really appreciate it!!
The Pixhawk has a built-in compass but because it is encapsulated with the other electronics, it picks up some interference and is not as sensitive. It is recommended that you use an external compass. The GPS module you are looking at buying has the Ublox M8N GPS AND also has a separate compass module in the same housing. It is NOT the GPS providing the compass heading. It is a separate module (most likely a Honeywell chip). They just share the plastic housing. You will notice that it has two connectors on the end of the cable: the GPS connects to a serial port on the Pixhawk and the compass connects to an I2C port.
Ardurover will only use one compass and it defaults to the external if it detects that one is present.
Thanks Kenny - very well explained!! Appreciate you taking the time!
I can’t wait to get something together this spring to hopefully be able to share with the group!
David
