pic: DiscoBots Nano-killough

[gpetilli]

Originally Posted by AllenGregoryIV

By our 2nd event, we had it working well enough for us to be the 2nd overall pick and make it the finals before losing to 118 and 1477.

What was the magic change that made the second event better? 2nd pick is fairly good, obviously your arm must have been great and your scoring was probably enhanced by the strafe capability.

[AllenGregoryIV]

Originally Posted by gpetilli

What was the magic change that made the second event better? 2nd pick is fairly good, obviously your arm must have been great and your scoring was probably enhanced by the strafe capability.

Getting the drive code under control, autonomous was about 100% (we used ultrasonic sensors to get to the pegs), arm and claw control improved, minibot was drastically improved, and more driver practice.

We also increased the speed of the drivetrain by changing the gears in the tough boxes, that helped a lot.

[gpetilli]

Originally Posted by AllenGregoryIV

We also increased the speed of the drivetrain by changing the gears in the tough boxes, that helped a lot.

do you recall the gears before and after? I think earlier in the post mentioned 10.7:1. We have been using 12.7:1 with 6" wheels and that seems plenty fast. Were you going for higher top speed, more acceleration or more control?

[AllenGregoryIV]

Originally Posted by gpetilli

do you recall the gears before and after? I think earlier in the post mentioned 10.7:1. We have been using 12.7:1 with 6" wheels and that seems plenty fast. Were you going for higher top speed, more acceleration or more control?

I believe we started at 10.7:1 and moved to 8.45:1. In 2011 we ended up having to go across half to 3/4 of the field regularly to get game pieces and the extra speed helped a lot.

At 12.7:1, unless my math is wrong, your actual speed is going to be under 10 feet per second. That's not fast by FRC standards. It really depends on the game and what you want your robot to do.

[Ether]

Originally Posted by AllenGregoryIV

At 12.7:1, unless my math is wrong, your actual speed is going to be under 10 feet per second. That's not fast by FRC standards. It really depends on the game and what you want your robot to do.

11 feet/sec at motor free speed. So yeah, actual top speed probably well under 10 feet/sec.

[gpetilli]

We are using the 12.7:1 gearboxes mainly because we did not want to spend money on an off season experiment. We need to better understand the limitations of Killough drive.

Two things we are doing that modify the standard calculations.

1) We plan to use MiniCIMs which have a free speed of 6200RPM (16.7% faster than CIM). Given that we don't intend to get into pushing matches, closer match to Jaguar current capabilities and the reduced weight, this seems like a trade we thought we should try.

2) According to Ether's kinematic calculations, by toe-in the wheels we lose cos(30) in torque but gain 1/cos(30) in top speed. This is another 15%.

At face value 10fps * 1.16 * 1.15 = ~13fps. Our crude estimator spreadsheet predicts 12.5fps front/back and >18fps lateral (1/cos(60)). We are planning to instrument and measure the step response on Thursday (students tell me the code and electrical are finally ready). I will report what we achieved by end of week.

Assuming we hit >12fps, do you think that would be competitive? If we are able to control it, and the game warrants Holonomic we can always change the gears in the TBnano to a lower ratio in the production robot.