4165 Offseason swerve

[matthewdenny]

Heres my back of the napkin calculations:

the motor is using ~23 Amps @ 12 V for a power of 276 W

The banebots page lists the motor at 78% efficient, so I'm going to round that down to 65%

so 35% of the 276 W goes to heat = 96 W of heat

96W * 150 seconds of game time* 70% duty cycle during match = 10100 Joules of heat

Q=mC(deltaT) ... m=337 g Csteel= .47

deltaT = 64 C

Which would make it pretty hot, but the motor blows air as it is moving, and conducts heat to the gearbox and surrounding air. Not sure how to calculate the convection through it.

[Kevin Ainsworth]

We run 100:1 on the steering gearbox with 2:1 from the gearbox to the steering wheel.
So 200:1 total reduction using a BB 550 motor.
And we only use one 1" wide wheel.
You also need to think about what happens in a defensive year when the bot gets loaded to one side and the wheel is trying to steer.

[Bryce2471]

Originally Posted by Kevin Ainsworth

We run 100:1 on the steering gearbox with 2:1 from the gearbox to the steering wheel.
So 200:1 total reduction using a BB 550 motor.
And we only use one 1" wide wheel.
You also need to think about what happens in a defensive year when the bot gets loaded to one side and the wheel is trying to steer.

200:1 seems a little conservative, but it is better to error on the side of robustness when it comes to swerve gearing.

I think we have hit the sweet spot this year between cool motors, and responsive controls. We are using a 64:1 P60 gearbox, fallowed by a 2:1 belt reduction for ~130:1 final reduction, on a 550 motor.

Last year, we had an 86:1 final reduction on an AM 9015. We never lost a motor because we used a torque limiting gearbox to prevent stall conditions. But the motors would frequently get hot, and the performance in pushing matches was lackluster.