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.
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.
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?”.
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.
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.
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.
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.
All our robots would look better in those little Canadian hats, with or without stepper motors. Knit cap - Wikipedia
(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.)
I understand the cost Of it, not saying that they would need to be supplied in the KOP, but why not make them legal. I dont see anyone complaining about the cost of the cRio’s…:rolleyes:
They aren’t cheap either but everyone benefits from them
At only 337watts the cim motor is not THAT powerful of a motor… The Brushless system of my Brushless rc car puts out more then double that. If you wanted something comparable to the cim in brushless form, it would be half the size and the only thing needed to use it are shaft adapters which can easily be made.
Historically, FIRST hasn’t allowed non-kit motors. The lone exceptions in recent years have been for the CIM motors, where two were provided with the kit (and a total of four would be legal). I’m sure someone with more time under their belt can expand on the idea behind that decision.
At only 337watts the cim motor is not THAT powerful of a motor… The Brushless system of my Brushless rc car puts out more then double that. If you wanted something comparable to the cim in brushless form, it would be half the size and the only thing needed to use it are shaft adapters which can easily be made.
The CIM motor is powerful enough to power nearly any manipulator a team could need, and more than powerful enough to tackle a person (or whack them in the chin–don’t ask). If it’s enough to let us send a robot screaming downfield at upwards of 10 feet per second, do we really need more power? Also, never rule out the importance of those shaft adapters–someone has to make them, and that takes money.
Also, perhaps someone can enlighten me about this: how durable are these motors compared with motors currently in the kit? Sure, they might be more powerful–but that’s no good if they burn up when stalled for a tenth of a second, or are particularly intolerant of abuse during assembly and testing. I missed out on the brushless era in R/C trucks (I quit racing when I went to college), so I’m unfamiliar with the state of the art these days.
The motors provided in the KOP’s are fine and easy enough to deal with. The fact that the motors and accessories are under so much restriction is a plus in my opinion because it’s one elss thing that a team has to worry about. We just need to learn how to deal with the restrictions and constraints. Plus, it makes things much more fun and interesting
The problem then is, as pointed out by multiple people earlier in the thread, it widens the gap between the “have” and “have not” teams. Motors have typically been (aside of additional CIMs and spares) provided in the KoP and teams have only been allowed to use the provided KoP motors. This ensures equality, as well as helps teams learn how to effectively use provided resources.
Nobody hear said that the CIM is that powerful, but it is powerful enough for virtually any FIRST application. Even in carpeted games, a two-CIM per side drivetrain through a transmission can produce more than enough force to break traction wheels loose from the floor. Once you surpass your static friction, additional force doesn’t do much good.
The motor alone isn’t the only thing that adds cost to a brushless motor. Teams would then need to buy addition speed controllers (though usually in the same ballpark as jaguars and victors) for their new non-KoP motors.
What voltage is the motor you linked to designed to run at? The one I found was designed for 10.5 and put out comparable numbers to a CIM, although was significantly more expensive.
