Why Hasn't first gone Brushless?
 

Hello all,
First post here, So I'll introduce myself. My name is Ben White of team 87- if any of you were at the granite state regional or Philadelphia regional- i was the tall black guy on drive team.. Kind of hard to miss me:p. I am team 87's hardware man and have a question


My question to you is why FIRST has not gone to brushless motors and speed controllers over the CIM motors, 884's and jaguars?
Brushless motors are loads more efficient, make more torque, and can be purchased with different winding configurations for different kv and Kt values.(rpm per volt and torque per amp).

For any of you that run hobby grade RC cars, you have seen the advantages of brushless motors. you get longer runtime, more power and the motors are less temperamental when under load.



What I would like to see is that first legalizes brushless motors and speed controls... yes they are expensive but they have their advantages.

Re: Why Hasn't first gone Brushless?
 

You just provided the answer to your own question.


-dave




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Re: Why Hasn't first gone Brushless?
 

I'm going to go out on a limb and say... cost.

FIRST would have to provide the motors to all the teams in the KoP.
The 2.5" CIMs are approximately 337 Watt motors, and cost $28 individually from Banebots. This brushless motor with a peak wattage of 350 costs nearly 3x as much.

Edit: beat to it

Re: Why Hasn't first gone Brushless?
 

Assuming that the rules allowed it, what motor driver and motors would you use? Do you have any specific parts to recommend? Along Dave's lines, could you also list the $$$ factor?

The powers that be at FIRST are reasonable, but they respond much better to "It would be cool to do X, and here is how we can reasonably achieve it" than "Why aren't you doing X?".

Re: Why Hasn't first gone Brushless?
 

Well if they just legalized them as in let teams use them without putting them in kits... you would have teams with ridiculous advantages over any team who can't afford the price tag on even a small brushless motor. An Axi-2208 which is a comparable replacement for a motor a tough smaller than like the Banebots.. is about $75. Not to mention the price of the speed controllers.

And FIRST can't afford to put them in the kits. I'm sure they can pick up CIMs surplus for under $10.. nowhere can you pick up brushless cheap for surplus so that's why they can't just include it in the kit. They cost a lot in general.

Re: Why Hasn't first gone Brushless?
 

I see the Lavery family suffers from cost consciousness (as does the Forbes family)

Efficiency is great, if you can afford it. Usually we can't.

Re: Why Hasn't first gone Brushless?
 

FIRST may go brushless for a water game. ;)

Re: Why Hasn't first gone Brushless?
 

If that were true we would have brushless motors this year.

Re: Why Hasn't first gone Brushless?
 

Yeah, and with the fairly high weight limit and short matches, there's really no design crunch to move to a more expensive/efficient motor. Although you're right, FIRST doesn't even allow teams to use brush motors that don't come in the kit; if they let teams buy comparable brushless you would start to see even more of a gap between well to do and not so well to do teams.


You make a very interesting point about the motor coefficients, too. Moving to brusheless opens up a lot of design parameters to which students don't currently have much exposure. Picking motors based on their performance and fit with your design becomes much more complicated and interesting.

Re: Why Hasn't first gone Brushless?
 

The jags and victors will work with most any brushed DC motor that is with in the power specs. With ECM motors the controller needs to be designed for the motor and that means more money and less flexibility. First can include any 12volt brushed motor they want to. With the NI C-Rio and the availability of CAN and LIN busses, First could include a brushless motor in the future. The automotive industry is going toward intelligent modules. In the future First could find a deal on surplus window, light, seat position, moon roof, rear hatch or other modules that use ECM motors. Then it would be up to Ni and WPI to write the interface for us.

Re: Why Hasn't first gone Brushless?
 

Luminary Micro makes reference motor controller kits for brushless, stepper, and AC induction motors. If FIRST wanted to foray into other motor types, I'm sure they could work it out.

I'd rather get stepper motors before FIRST went brushless.

Re: Why Hasn't first gone Brushless?
 

I agree. This would be a better next step ;)

Re: Why Hasn't first gone Brushless?
 

Some stepper motors would be pretty sweat. Holding toque for a stepper motor is really nice..

Re: Why Hasn't first gone Brushless?
 

All our robots would look better in those little Canadian hats, with or without stepper motors. http://en.wikipedia.org/wiki/Tuque

(EDIT: Kingof1337 made an innocent typing error that generated something even better. I had no intention to make fun of anyone. My screen name is an example of my own ability to miptyse something.)

(EDITED AGAIN: It's an Internet rule - predating the WWW - that all criticisms of someone else's grammar or splelling should contain a similar misteak.)

Re: Why Hasn't first gone Brushless?
 

As is your response. :)

-dave