Quote:
Originally Posted by Ether
Nice. Did the wheels break traction at the starting line when you hit it with full throttle?
Could you please share a few details about the math here? How did you calculate the 80% and 90% numbers?
EDIT: just saw IKE's earlier post about posting a paper. I agree. In the meantime, perhaps you could whet our appetite with a few details as mentioned above.
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The wheels did not break traction. We're running 4 CIMs on a pretty heavy robot.
As for the efficiency numbers: The drivetrain's free speed, without any efficiency losses anywhere, is easily calculable from CIM free speed and gearbox reduction. I used the frame data to get a distance-over-time graph with 11 points of data (0ft-20ft at 2ft intervals), then ran a power regression (r^2 =~= 99.5%) to fit a curve to it. I took derivatives to estimate velocity and acceleration, but these were not too accurate because the robot hit its top speed before the end of the 20ft. How do I know that? The last 5 data points in each gear fit a line (r^2 =~= 99.9%), which I used to calculate top speed. I then compared this with the theoretical free speed of the drivetrain to find the efficiency.
After that, I talked to my physics teacher, and was able to draw all sorts of interesting conclusions about the factors that affect efficiency. I had originally hoped to come up with a differential equation that could solve for efficiency based on major factors, but after these tests, it's very clear that this equation would not only be extremely difficult to solve, but also nearly impossible to generate in the first place. I might expand on these points in a future white paper, but I have a lot on my plate at the moment. Hope this helped.