From my understanding, the 2.75" Omni-Wheel (compared to the 3.25") has Better Acceleration but a Lower Top Speed (on a drivetrain). Possibly, the 2.75" also has More Pushing Power (this could be due to either Torque or Force—I’m not sure).
Does the 2.75" have Better Pushing Power on a Drivetrain compared to the 3.25"?
Please correct me if I am wrong.
If used at the same speed, 3.25 has faster top speed but lower acceleration. But often smaller wheels use faster drive ratios.
Your fundamental understanding of the math behind calculating drive speed is flawed.
the equation is
(wheel dimeter)(pi)(wheelrpm))/60
this gives you inches per second. as you will notice if you run a couple calculations you can get similar speeds by just changing hte wheel rpm and wheel size. for example,
(3.25)(3.14)(360))/60 = 62 ish and
(2.75)(3.14)(450)/6 = 64.5ish and
(4)(3.14)(300)/60 = 63 ish.
this is jsut a really small sample but as you can tell by changing wheel rpm through gearing or chaning the wheel speed you can get any linear speed you desire pretty much. All drives with similar speeds have similar torque. The linear speed of the robot and the torque the robot has are inversley proportional for the same amount of motors. this means that for more lienar speed, ie 100in/s you will have much less torque than 50in/s for the same amount of motors. The wheel size realisitacally has no effect on this.
if you were theoretically running the wheels all at the same constant RPM, ie 200rpm, then the 2.75 wheels would have the most torque and the 4inch would have the most speed because per revolution the 4inch travels much further due to its large circumference.
check out this thread and look at what kind of speeds you can run keeping in mind higher linear speed means less torque for a constant amount of motors.
So if 2 robots with equal mass were to push against each other. But one had 2.75" Wheels and the other had 3.25". The 2.75" would “win” (push the 3.25" robot back)?
Assuming that the wheels were being driven at the same RPM yes. if the wheel RPM was scaled so that the robots were the same linear speed then no. it would be dead even. if you want an obnoxiouse example,
a robot with 5inch wheels spinning at 100rpm ,(5)(3.14)(100))/60 = 27 in/s would push the crap out of a robot with 2.75inch wheels at 600 rpm, (2.75)(3.14)(600)/60 = 86 in/s. to dumb it down a whole bunch the number you pull out of the linear speed equation tells you how much u can push compared to another robot. so 27< 86 so the 5inch wheel robot wins in this case. (to be clear this example is an extreme just to show that small wheels doesn’t mean more pushing power)
The answer is complicated by the fact that the brain will provide more power to motors to attempt to achieve whatever velocity you are requesting.
