Building a 6-wheeled rocker-bogie vehicle that Ben posted back in September (http://diydrones.com/profiles/blogs/introducing-the-nomad-working-t...).
I'm new to land ROVs and wanted to know if APM or Pixhawk and the code support 6 drive motors and 4 wheel steering servos? And what additional hardware I would need to make it work.
Assuming that the three motors on each side of the Rover are powered by a dual channel ESC, like a Sabertooth 2X25 ESC, where each of the channels powers three motors, the answer is yes.
Normally this type of Rover configuration would be controlled by using skid (differential) steering.
The four wheel steering has been asked about in the past, but I do not know if it was ever implemented in the firmware.
At the time of writing 4 wheel steering isn't implemented.
Ok thanks. I guess this puts a halt to my build as I'm not a software developer and this type of power train and steering is outside my skill level. Is there a chance someone could develop code for this design?
I don't have the capability to print one of these designs so I can't test any code. I sponsored the wrong kickstarter campaign to get a 3D printer and lost my $2000.
However, a "get it up and running" hack could be possible for you. At first I thought if you plug all the servo's into the same channel using a gang of Y cables you might get lucky and they all move in the correct direction when you steer.
Alternatively I could add RC#_FUNCTION of steering. This means you could plug the servo's into channel 4,5,6,7 for instance and designate each one RC#_FUNCTION of steering. That way if one of the servo's needed to move in the other direction you can reverse it with the RC#_REV on that channel. That would be relatively easy.
Has four wheel servo steering been implemented in Ardurover? I have a simular 6 wheel drive, 4 wheel steering rover that I am building and I'm going to use a pixhawk in it. Also, for the 6 wheel drive motors, I am using a roboclaw 7 amp motor controller. Does pixhawk/ardurover support this controller? Here are some images and a short clip.
My apologies to the broken video link, here it is.
No response? I am really needing this feature implemented for U-turns and Turn-in-place maneuvers.
I have seen your pictures and the movie. How do you intend to steer?
If your rover can use skid-steering all you have to do is connecting all motor on each side to the same output. For DC-motors you can have one driver and connect the motors in parallel or send one output to three drivers with the same result.
If you need to "bend" the rover to steer and use DC motors I'd experiment in connecting a DC motor between the drive for the left and right side in the way that is gets the difference in voltage. I have not tried this but it should work.
My 4 cents
Thank you Anders for the reply. I have since figured out how to do many of the things I was asking for help on. I have since implimented only Turn-in-place steering on my rover in a config like this and it works great
However, my next tackle is also figuring out how to do arc turns in a config like this. Doing either one is simple by itself, but doing both turn-in-place as well as Ackermann style 4 wheel steering, still figuring out.
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Here is an FPV video from the rover demonstrating 4 wheel turn-in-place steering.