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Will two drive wheels and two casters give you the traction you are looking for to shovel snow or traverse a garden?
using the P&G drive would remove the need for a Microprocessor as a hart beat also saving $100.
But it has built in acceleration/Deceleration loops that would cause me issues while under autonomous control.
I should then have the budget to get tracks(if needed or usable (could cause damage to lawn or garden?)
A µcontroller is just a few bucks, but I don't see why one motor would need it while another wouldn't?
Why would it?Just use encoders on either the wheels or the motor shafts and count pulses, then you know how far each wheel traveled. With a bit of testing, you will probably find how much you need to modify a given distance at a given speed for complete travel.
Just use encoders on either the wheels or the motor shafts and count pulses, then you know how far each wheel traveled.
Why would tracks damage the garden more than wheels (as long as you don't rotate too much in one place)?Tracks will spread the weight over a larger area, so it will be lighter per square area of contact.
If the main controller(PC) shuts down for what ever reason and the DAC voltages go to 0v with the Sabertooth or RobotQDrives will go Full reverse and full CCW turn until the batteries drain, drives fail or the test bed ends up in Cleveland.With the P&G drive if the main controller shuts down and the DAC voltages drop to 0v the drive will shut down and showa fault. also if I power up the drives with the main controller(PC) turned off the Sabertooth and RobotQ will take off, butnot the P&G drive, it would show a fault.
Because I'm not doing random cutting paths(I hope) any deviations from the target path will cause me a problem, with the Sabertoothand RobotQ drives even if one wheel runs over a toy the kids left laying around or even Dog crap(my mother has a dog) the drivecan make the speed and direction correction very fast(full reverse to full forwards in .5 seconds), because of the Acc/Dec programedinto the P&G drive it takes 6 seconds to go from full reverse to full forwards. .5 sec = @2.5" linear travel 6 sec = @30" linear travelmowing deck on test bed 20", I want it to be 48" when project completed.
because of the reason listed above(dog crap, toys,gopher holes) I can't use the drive wheel in the velocity or positioning loops
I was thinking about all that friction while turning, but also how much wider and long they are, and can my mom plant her carrotswithout running over the ones she already planted?. I have never used tracks before so my information in very limited.I willing to give them a try.
You wouldn't need a full reverse in such cases, just minor adjustments and when mowing the lawn
so I'll still recommend encoders
As long as you make all of it yourself, you decide how wide they're gonna be and of which material.
nice idea but it seems a bit under engineered.
first off from your diagram it shows casters. casters are a death trap on grass and dirt.
is it worth spending 2500 on a robot that you have to remote control to cut grass when you can get a riding mower for 1000?
also why would you have a wheelbarrow sort of thing if you don't have anything to fill it with?
lastly i think you could do that with half the budget if not much
in fact you will need to change the wheels to something bigger if you intend to use it at all.
To my surprise the Mule spines even the wider tires when climbing 20deg on wet grass.
With the mass being equal, the wider tires, while having a larger footprint, have less mass/square" of footprint.
Perhaps if you pair up a combined drive wheel and lawn aerator...
While I can see the logic of the above line, there must be some variable overlooked. Because it seems like the newtires draw @30% more current then the old tires, in my head I see that caused by greater friction between theground and tire, which may also be the reason it makes the Mule more sable on uneven surfaces(which is a good thing).
I don't have drive current feedback my only justification for the 30% value is by testing with different motor drive power input fuses, like install a 10Amp fuse then perform a task that would make the fuse fail then increase the fuse value until the task is performed.(gone through 3 boxes so far at @3.00 each box, seems I should install feedback soon).
My next effort is to replace the 2 pole drive motors with 4 pole, in hopes of getting better low speed torquein hopes of keeping the tire from slipping. it also gives me the opportunity to open up the gearboxes andremove the lost motion before they are installed.
Soeren, if I installed something like the picture below, my mom would start to cry just looking at it.and I wouldn't get too close either, these big testbeds can be a handful.
It was a generalization. You also get better grip in snow and ice if you let out some air on your car tires and the tire pattern can have a lot to say.
"Remove the lost motion"??If it's lost, how do you remove it?
Why not gear down for less speed.
hey, why not kill two birds with one stone...
Looks goood
Without having any snow removal by plow experience I figure I should make my own snow plow for the Mule.that way I could make changes cheaper and faster.
For proof of concept, an all plywood approach is fine, but a bit of metal underneath it will make it last longer.