My work in progress: Traxxas Stampede Brushless PX4 APMrover
Now you see it!
Now you don't!
PX4 Safety Button / LED indicator Access and Buzzer port.
Sort of a stealth APMrover, although plans for dual SONAR may be a bit more obvious.
(Maybe I can disguise them as off road lights).
And, of course, no SONAR till one of the highly esteemed developers puts APMrover SONAR capability on the PX4.
Going to try to do this with an 8 channel PPM encoder and a stock Traxxas 4 channel rock crawler type transmitter (not the 2 channel one that came with it).
The 1/8" T6 polished aluminum diamond plate base plate is a bit of overkill and I need heavier springs.
But I am planning on mounting some interesting stuff on it and it provides excellent EMF shielding for the PX4 and the magnetometer in particular.
The latest APMrover code is installed in the PX4 and is functional, but still need to get an encoder for it.
I will post updates here as this project progresses.
Should be fun!
Comments
Looking at another possibility, I have PX4 flow cam which has built in controller and frame buffer for processing.
Combine this with a laser line generator offset and can read differential offsets of line pixels directly as distance.
5 MW Laser line generator $20.00.
A 1D scan could yield a full frame depth pixel matrix
Accuracy would be limited and decrease with distance, but that is pretty much what you need for navigation anyway.
Web cams can do this too but you'd need an intermediate processor for interpolation.
@Gary,
Thanks for the range finder insights. LIDAR is still expensive, but is slowly coming down in price fortunately. Looks like there will be lots of exciting options on the horizon in the near future.
Regards,
TCIII
Hi again Tom,
Lightware actually has a potential LIDAR (low scan rate) solution that might be useful.
I've looked at them before and now he actually has a chip with all the right stuff on it for $35.00 and sells a ready to interface (rangefinder) for $500.00.
http://www.lightware.co.za/
One of the bigger problems is location South Africa, but he has the closest thing to a viable solution I have been able to find and he is working on a Arduino interface version.
Another facet is that the update rate is from 1 to 20 hz depending on distance (60m - 1hz I think), but for the most part for our use probably ~ 20 hz would actually work OK anyway.
Hi Tom,
Those are really nice chassis, especially like your combination shock tower SONAR mounts.
Agree totally with you regarding inadequacy of simple SONAR system.
SONAR is problematic in a lot of ways, I am going to be trying a servo scanned tight beam horn type SONAR and hope to be able to improve on current SONAR performance.
Main reason for PX4, basically same sort of (result) as Laser scanner, just lower resolution.
I will also be following up with LASER scanner, but frankly these are just to expensive for home use (except for ripping apart Neato vacuum cleaner (which uses stereo offset instead of TOF for distance calculation).
I do think a scanned (camera with a laser pointer) capturing the stereo offset of the laser dot (or better line) is about the best inexpensive way we can do reasonable pathfinding.
TOF LIDAR is illusive because the high speed timing circuitry and avalanche mode devices required are hard to come by, expensive and very tricky to work with.
There are some conversion projects for off the shelf laser rangefinders, but their recycle time is so slow as to render them practically useless.
If you know of a superior TOF solution I would sure like to know about it.
Nice work Gary. The PX4 looks a little lost on that aluminum plate. The PX4 would be right at home on a 1/16 scale rover.
Very similar in size to my Slash rover of which I have two now. One for development and one for the AVC.
Based on my testing with the Maxbotix MB1240 sonar sensors, I would prefer a LIDAR that would be immune to false triggers and could continuously map the environment ahead of the rover to determine the optimum path around obstacles when moving from waypoint to waypoint.
Here is a picture of my Traxxas E-Maxx chassis that is guided by an APM1.4/Oilpan combo.
Regards,
TCIII
Very Nice Gary! Thanks for sharing this with us.