Understanding the motors.

Technical Motors
1

I have two primary questions:
I really want to understand what differentiates each motor from each other. I already understand some of the importance of CIMs, and that Banebots can also be a valuable asset due to their high torque, but I still feel that having a post where each parts are discussed would not only be valuable to me, but could serve as a useful asset to others; considering the sheer number of different motors we can use, getting them all compared together in a single post.
I’ll post pictures for each motor so you have links to each if you want to point out things out on them.
As FIRST states:

"The only motors and actuators permitted on 2012 FRC Robots include:

  1. up to 4 CIM motors (part #FR801-001, M4-R0062-12, AM802-001A, 217-200, PM25R-44F-1005 or PMR25R-45F-1003),
    http://www.vexrobotics.com/media/catalog/product/cache/11/image/296x/5e06319eda06f020e43594a9c230972d/2/1/217-2000-cim-motor.jpg
  2. up to 4, in any combination, of the BaneBots motors provided in the KOP (acceptable part numbers are M7-RS775-12, M7-RS775-18, M5-RS550-12, M5-RS550-12-B, and M3-RS395-12),
    http://everobotics.org/projects/robo-magellan/img/big/bane_bots_mp-28005-385.jpg
  3. up to 2 window motors (acceptable part #s are 262100-3030 and 262100-3040),
    http://www.firstcadlibrary.com/images/ND%20Motor%20Right.gif
  4. up to 2 FisherPrice motors (acceptable part #s are 000968-9012, 00968-9013, 00801-0673, and 00968-9015),
    http://kamocat.com/robot/planetary/rearview.jpg
  5. up to 2 AndyMark motors (acceptable part # is am-0912),
    http://a248.e.akamai.net/origin-cdn.volusion.com/vyfsn.knvgw/v/vspfiles/photos/am-0912-2T.jpg?1325767877
  6. up to 2 AndyMark gearmotors (acceptable part # is am-0914),
    http://a248.e.akamai.net/origin-cdn.volusion.com/vyfsn.knvgw/v/vspfiles/photos/am-0914-2T.jpg?1325767858
  7. up to 2 Denso throttle control motors (acceptable part # AE2351000)
    (not sure what it looks like)
  8. up to 2 VEX motors (acceptable part # 276-2177)
    http://robomatter.com/images/ifi/2-wire-motor-393.jpg
  9. up to 2 window lift, seat, windshield wiper or door motors obtained through either the FIRST-Automotive Recyclers Association partnership or from a prior years’ KOP. "

Also, I am really curious how mounting for each of the motors vary; some are obviously different (like CIMs and window motors), but what are different ways you could mount each and what is the general theory behind it and are there any disadvantages to mounting certain motors in certain ways? Answers to any of these questions is greatly appreciated, thank you for very much.

2

Hi, I’d like to answer some of your questions, but it’s really hard to read the post because you linked to a huge image. If you could crop that image down to a reasonable size (less than 801 pixels wide), it would make it readable.

3

Cim motors are typically your drive motors because of their power output.

The banebot motors are used for tasks like driving a ball lifter or actuating an arm of some sort. (We’re using them for our ball launcher this year)

Window motors are on the slower side of the spectrum but have power because of the gearing inside.

Fisher Price motors are pretty strong. comparable with the banebots motors but need more work to put a gearbox on or any type of linking mechanism. They also don’t mount as nicely as banebots do.

As for the next 2 or 3 ive never worked with them so i couldnt tell you. I would look at their spec sheets and see how they compare with the others.
(AndyMark should have the info on the product page)

And the vex motors are used for very small devices like maybe a camera actuator. They cant handle much stress (because of the plastic gears inside) and they will stall causing you to burn out the motor

Thats about it. I hope this gave you a good guide to the motors allowed for this year!

Goodluck!
-Thomas

EDIT: As per the user posting above me, please crop photos before posting. Thanks!

4

Gears don’t make a motor more powerful. They just trade speed for torque.
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5

Fisher price are very nice when used with a CimSim gear box which gives them the same output shaft and rpm as a cim motor. You can mount two Fischer prices into a CimSim. We are using that setup for our shooter.

6

The specs on most allowed motors can be found here:
http://www.usfirst.org/sites/default/files/MotorInfo4.1.pdf

Basically, the choice of which motor to use comes down to a few important items:

  • power
  • torque
  • speed
  • heat dissipation

I’ll address these items in reverse order. (a word of warning… the descriptions here are all for typical scenarios. I’m sure someone will post an example that proves something here isn’t a “rule”)

The CIM motors, due to their size and completely enclosed design, are typically the best to use for the drive train. They can take the most abuse and dissipate heat better than the other motors. Many of the other motors have internal fans (you can often see them through holes or slits in the casing) that push air over the armatures to help cool them. These motors are very bad to stall, as the air stops moving, your current draw increases, and your heat increases.

Speed and torque go together, really. When designing something, you often either need to meet a certain speed (a shooter that is set up like a pitching machine, for example, will require a minimum RPM to shoot the ball effectively), or a certain amount of torque (tipping the bridge down, for example, will require a certain amount of force applied on the bridge, which can be provided as torque from your motor). These requirements can often help to define which motor to select. For a shooter, you’ll go with a fast motor that can be geared to meet your speed requirements. For the bridge tipper, you’ll go with a slow motor that can provide enough torque on your lever arm to push it down.

Gearing can allow you to “trade” speed and torque, much like the gears on a bicycle do. When you’re on a bike and reach a hill, you’ll shift gears. That way, you can peddle faster, but move slower - you’ve transferred your speed into torque to help you get up the hill. When going down the hill, you shift gears in the other direction - you peddle slower but move faster, because you don’t need as much torque anymore. Keep in mind that all gearing causes a loss of power (although not so much that it’s worrisome in most applications), so you want to avoid any more gearing than is really needed for your application. For example, you could gear a window motor to power a shooter… but you would need so many gears to do that at a decent speed (plus the gears that are integral to the motor itself), that it’s not really practical.

Finally, we get to power. Power sort of sums everything up. A more powerful motor can deliver more torque at the same speed as a less powerful motor. Since it also draws more current, it also ends up heating up more (assuming heat dissipation is identical for the two motors, which we know it isn’t when comparing, for example, a CIM and a BB 550).

7

And now an answer for your second question (didn’t see it at first)…

Mounting is entirely up to the design of the individual motor. Some motors, like the FP’s and BaneBots follow standards for 500- or 700-series motors, so mounting a 550 in a gearbox designed for a 500-series motor (regardless of the manufacturer/source of the gearbox) typically works fine. The CIM’s mount in a similar fashion (two bolts into the front of the motor). Typically, you’ll mount all of these into a gearbox, then mount the gearbox to your robot with whatever mounting hardware the gearbox has.

Other motors, like the window motors, have gearboxes already attached as an integral part of the motor. For these, mounting is generally a little different, as you’re really mounting the gearbox and not the motor.

So in general, you’ll want to worry about your gearing first (figure out what sort of gearing is needed), then mount the motor to the gearbox, and the gearbox to the robot.

8

Has anybody gotten a picture of the AE2351000 Denso motor

9

Does anyone know which Fisher Price motors have internal protection circutry and what type ie: thermal or current limited? I posted this question in detail in the “Official 2012 motors models and specs thread” but there have been no replies in a few days.

10

Actually the Vex motor (393) we can use has steel gears.

11

There are huge differences between the various Banebots motors, to say nothing of the fact that the image you’ve included isn’t actually of a motor, but rather a motor-gearbox assembly. They all have different power outputs (the 775 being the most powerful and the 395 being the weakest), but given the wide range of options they offer in comparison to FPs, they’re a great option to consider.

The window motor is also actually a motor-gearbox assembly; the metal housing on the end is the actual motor, and the plastic casing a gearbox that includes a worm screw and locking pins that prevent backdrive.

I’d recommend reading through Mabuchi’s motor guide to get a better understanding of how exactly motors work, which in turn will allow you to familiarize yourself with the various motors more easily.

12

Keep in mind, however, that for the purposes of FRC, the gearbox is considered integral to the motor, and the motor cannot be used without it, and the gearbox cannot be modified, except as permitted by R49.

13

The Denso Throttle Control Motor is:
http://www.andymark.com/Throttle-motor-fc12-20-p/fc12-20.htm