Hi,
Let us present AirbotServices' style Ardurovergasmistic week-end gaming - lvl 1. It is mandatory to pump the volume up when watching this video.
This all-terrain monster consists in a Pixhawk controller running latest Ardurover code installed in a 6 AWD chassis.
All six wheels are self-powered with an independent motor and are using a 75:1 gears ratio. Such a high ratio gives it a tremendous amount of power, as you may have observed in the video. Certainly not made for high speed rover sissies :)
In terms of equipment, in this first stage, AirbotServices ' rover remains practically naked, still equipped with:
-a M8N GPS+compass module
-3DR telemetry radio
-3DR power module to keep an eye on current and voltage in real time
-A Sabertooth dual motor driver (credits to our community Ardurover expert, Thomas, for helping me out on the settings !)
-FrSky D4R receiver
-Payload capacity (not counting chassis): 6kg
In a second stage, camera(s) setup with stabilized gimbal and vibration dampening. This will be quite an interesting challenge to get vibration free video on a rover and a level2 video might follow...
Ultimately such a little beast will be given a brain via a companion computer for "ground/underground" agricultural purposes. We were thinking on adding a small quadcopter companion, taking off/landing on top of it, using precision IR beacons of course, that would relay images to the rover companion computer. Or even swarms of micro quads launched by the rover ?
What do you think ?
Comments
The E-Maxx and Stampede are definitely built more for speed and would not work well for what you want. The Summit, while being brushed, works quite well. You just leave the differentials and the shifter for the high/low gearing in the position you want and you don't need to mess with it later. It's not complicated like you would expect and requires no setup if you have it on separate channels on your radio separate from the Pixhawk.
The high gear can be quick but it's only about 20 mph in high gear. It's more like 10 mph or so in low gear and is my preferred method of driving around, especially for FPV.
I think it's the toughest Traxxas of them all but it's also a bit pricey. There are cheap enough brushless systems for about $100 you could strap on to make it faster and more efficient but it's not sensored so you can still get some of the issues when the phases in the ESC don't line properly. You also loose the waterproof ability of the vehicle with the change too.
Again, the downside is higher CoG and potential high centering since it doesn't have wheels in the middle like the Dagu but it's very versatile and worth consideration for just getting around. I do like the look of the Dagu and may consider it some time for my next ground vehicle, if I ever get around to it!
Thx for the link and the roll cage idea, Thomas.
@Gary, i would be interested in this chassis too, if you find them back.
Hi Thomas,
There actually is or was a company that makes a nice heavy duty 6wd chassis like you describe with chain drive between the 3 axle units.
I am not sure it is still in business, but I will try to find it again.
It is a bit bigger than the Thumper, but looks seriously heavy duty.
The above listed concerns are what kept me from getting the Thumper in the first place and it is definitely interesting to see them confirmed.
Best Regards,
Gary
Very interesting Hugues, what they monitor between rows?
@Cala, actually, the university I work with (responsible for making me try a rover UAV) did show me a picture of a huge 2,5meters long rover, 4AWD, certainly able to carry 100kg. Unfortunately I did not receive more technical details about it.
The 50 cm size category of the 6WD thumper is actually better for them because it is small enough to travel between planted rows in the fields...
@Antonie, great build, impressive ! So it is clear our next move should be to look and find a good metal high quality replacement motor that could be fitted on this chassis. The hunt starts now !
@Thomas, yes the GPS should be placed higher and I actually did put it on a pole at first but the pole crashed when I flipped the rover :). Is there an advice there for making it "flip" proof ? Are you happy with the lynx motors you mentioned earlier and can those be fitted on the Dagu ?
other question : did you find a gear reduction of about 75:1 for an e-maxx chassis ? If yes, I would move to a Traxxas chassis.
I dream a vehicle like these but bigger scaled to carry for example 100kg payload and can sprayed pesticides or disperse bait, pick soil samples or monitor insects on the soil......or cut my house grass; sounds reliable with a pixhawk and RTK like piksi?
HI Hugues, great video. Love the Thumper. Just a note on the slew rate of those motors. The gearboxes fails quite fast if you do not spread the load transfer over half a second or so....or dump the stock motors and get a better quality one. I cut the spikes off my tires to try and reduce the torque on the axles. I also replaced the transistors on the H-bridge after they fried when the Thumper fell in a ditch during an auto mission and the undercarriage got stuck. I'm using the Wild Thumper controller - it is suppose to have a current monitoring system that blows a fuse when thing goes south, but it didnt. Replaced 2 motors as well. In total 5 motors now. 3
with
stripped boxes and 2 fried.
Great idea, great chassis but those motors and boxes are not. I'm still looking for better quality ones. I'm considering a scaled up build with bigger motors for better reliability.
I forgot to mention that my Thumper works for a living. It is not a hobby rover. I use it to collect quality control samples on construction works being tracked by a survey instrument:).
Thank you all for comments.
@Healthyfatboy, this is my first "real" rover experiment. I had played a year ago with a small plastic chassis (actually the one shown in the ardurover wiki) from hobbyking. Parts were literally falling apart and this chassis was unable to drive on anything else than a flat road. In the end it came to be expensive because of all the replacement parts I had to buy and the time I fiddled on it. Thomas advised me too on trying "Traxxas" brand chassis (e-maxx for ex). I have never tried it. I choose for the Dagu chassis in place of the Traxxas because of the future use I intend to do for agriculture where I need an all-terrain vehicle that drives slowly enough. The e-Maxx is more of a speed vehicle (the smallest version drives at 30 mph!) for racing, not for agriculture.
@Felix, Yes that is what I will try next too. FPV blast !
@Cala, come one, let you be tempted by this orgasmic robotic blast ! I did not test the radio range on the rover. This can be a nice test I can do. I will report back. However in the intended field use, autonomous behaviour will be used , so no RC control intended (so we don't care of the radio range really in this application).
@Gary, your stampede experience is useful for me as it confirms what i suspected too. The low gear ratio of these Traxxas vehicules make them drive way too fast for agricultural usage. And , as you say, I do not want to start a "pimp my rover" thing where you need to customize complex differentials, clutches, gears and the like... I also notice in Europe the price of Traxxas chassis is very high, almost triple the price of this Dagu chassis (motors included).
I would say the weak points of this Dagu chassis are the brushed motors (i would prefer brushless motors) and some weak wheel attachment design. This could probably be customized to improve it. What's good though is that replacement motors+integrated metal gears are sold quite cheap (about 12 dollars/motor).
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