How fast r u gonna go?

[JVN]

Originally Posted by Tristan Lall

John, do you have any information about the test conditions used to establish the 81%? And how much does that vary? (I've always made a similar approximation, but I don't have any hard data to back it up.)

About 8-9 years ago when I was teaching myself this stuff I designed a drive using 81% as a magic number (I think someone on the forums mentioned this) then tested it -- the experimental matched the theoretical. It has just sort of turned into a "rule of thumb" for the typical style of drivetrains. I know some will be a touch slower and some will be a touch faster, but I've never been pissed off if I design at 81%.

I'm humiliated by how unscientific this is, but it seems to work for me.
I don't have hard data... just 9 year old, soft data...

-John

[ks_mumupsi]

From the last 11 years of seeing a lot of different drive trains, I have to say practice makes one of the biggest difference in ability of drivers to handle speed.

In Overdrive, we used 4 CIMS with a 7:1 reduction using the AM Stackerbox with an ackerman steering, which seemed to work really well, we approximated our drive speed to around 22fps.

Last year, we went a completely opposite direction and designed an 8 wd using 8" skyway wheels, we were an even match for even some of the lowest geared robots. It all depends on whats appropriate for competition. This year on a flat field I see advantages to a 2 speed transmission in gaining speed but I dont think it will help with anything if the drivers cannot learn the change the speeds well on the fly. The shifters now have gotten far better than they were a few years ago.

[team 3311]

here's and idea try making a programing shiter aka dumb down your contlers imput values then have a easy byttion to go to full speed

[team 3311]

here's and idea try making a programing shiter aka dumb down your joysticks imput values then have a easy byttion to go to full speed

[Bruceb]

Well, the reason most folks use a shifter is to have a LOT of pushing power and what you are suggesting will just slow it down.
Bruce