Official 2012 Motors Models and Specs Thread

[Mark Sheridan]

Originally Posted by Ether

I should have been clearer. The point in contention is this: Timz3082 is claiming* that the motor portion of the PG71 (am-0914) is the same motor as the 9015 (am-0912). I was asking where he got that information.


* see post #5: "That is with the gearbox, without it is 180 W"

Ahh, I see we are on the same page.

[Ankit S.]

Does anyone know which motors are back-drivable and which motors are not?

Also are there any motor curves up yet? The page on the FIRST website does not have this.

[theprgramerdude]

Originally Posted by Andy Baker

These numbers, posted by me on the AM website two days ago, are not correct. They have been updated to much more realistic, and larger numbers. We at AndyMark are changing these numbers a bit after some further testing this weekend. Sorry about this change. Please check our PG71 web page for any further updated information.

Here is more to the story.

When I was updating the web page for this motor on Friday, getting it ready for Saturday's kickoff, I saw that the stall torque was listed at 11 amps. This is information we got from the manufacturer. So, I called Mark, who was out at Manchester for kickoff to see what was up with this. He created and interpreted the performance numbers a few weeks ago, and listed the stall torque at 11 amps. We both thought about this some more and agreed that was waaaaay too low. He got home today and did a bench test that repeatedly performed at these numbers below. This test was ran with a 12.8 volt battery providing voltage directly to the motor. The stall torque is 23 ft-lbf, and the max current reading is 28.6 amps. We believe this translates to approximately 350 watts as the max power for the motor.

Tested at 12.8 volts
23 ft-lbf max torque at stall
28.6 amps pulled at stall
Estimated 350 watts of power

Here is Mark's setup. He had a force gauge measuring an arm's pull at exactly 1 foot away from the motor. The force gauge showed 23 lbs of force and the amp meter showed 28.6 amps. It was a simple setup, and we ran it about 10 times. The numbers were consistent. These numbers make much better sense to me compared to the "11 amp stall torque" numbers I posted on Saturday.

Again, sorry for these erroneous numbers yesterday, and please check out the PG71 website for future updates.

Sincerely,
Andy Baker

I don't know if I'm doing this right (actually, I'm pretty sure I am), but if you input 28.6 Amps at 12.8 Volts, that's equivalent to 366 watts of electrical power being put into the system.

350 watts of output power translates to >90% efficiency for a 12V motor, something that is ridiculously high.

Or, maybe I'm reading this wrong, and you're simply stating that it can pull about 350 watts of power, and not the output power... I'm confusing myself.

In the retest, was the torque due to the arms weight accounted for?

[sanddrag]

Regarding the Automotive Recycler's Association motor deal, I found this press release: http://arav3.timberlakepublishing.co...p?Display=1476

My question is, can we simply buy and legally use any motor from a car rather than obtaining it through this route? If not,I think it's dumb that a piece of paper from a junkyard is the difference between a motor being legal and not.

[Tom Line]

I can't believe we'd be allowed to use any motor at all. I'm looking forward to more info too. There has to be a reasonable limitation on what can be supplied.

[Ether]

See notes embedded in red:

Originally Posted by theprgramerdude

I don't know if I'm doing this right (actually, I'm pretty sure I am), but if you input 28.6 Amps at 12.8 Volts, that's equivalent to 366 watts of electrical power being put into the system. Yes, that's how you would calculate the electrical power into the motor at stall. There is zero power output at stall.

350 watts of output power translates to >90% efficiency for a 12V motor, something that is ridiculously high. There is no mechanical power output at stall. You can't divide the 350 by the 366.

Or, maybe I'm reading this wrong, and you're simply stating that it can pull about 350 watts of power, and not the output power. Power rating should be the mechanical output power. See this post for how it's calculated.

[Ether]

Originally Posted by BeltSanderRocks

are there any motor curves up yet? The page on the FIRST website does not have this.

You can use this to do all your motor calculations if you want to.

It now supports the following 2012 motors:

CIM

FP0673
FP2719
FP9012
FP9015

RS395
RS540 (not legal for 2012 but included)
RS550
RS775-12
RS775-18

am-0912
am-0914

DensoL
DensoR
Denso AE235100-0160

[RyanCahoon]

Originally Posted by BeltSanderRocks

Does anyone know which motors are back-drivable and which motors are not?

Also are there any motor curves up yet? The page on the FIRST website does not have this.

Motor curves are linked on this page. Currently, the PDF file is here, but the filename appears to be changing with each revision.

[fox46]

Ether- do the specs on that PDF look kosher to you? I trust your experience far more than FIRST spec sheets!

[rbrown1]

Maybe someone can help me. The Fisher Price motor we have in the kit supplied this year is a 00968-9013. Is there any motor data for this motor available?

[Ether]

Originally Posted by RyanCahoon

Motor curves are linked on this page. Currently, the PDF file is here, but the filename appears to be changing with each revision.

The only changes from the initial revision are as follows:

1) corrected typo in Line1. Was "am-9012". Now is "am-0912"

2) corrected typo in Line2. Was "am-9014". Now is "am-0914"

3) changed data in Line2. Was/Is: 18.28/69.07 1309.4/4416 75/84 1.2/1.2 11.3/28.6

The new data is misleading. The Stall Torque and Stall Current are reported at 12.8 volts (and this is not indicated in the chart).

To create motor curves, use (12/12.8)*4416 = 4140 oz-in stall, and (12/12.8)*28.6 = 26.8 amps

Also, the power at 12 volts should be 64.3 watts. See post#10 in this thread.

[Ether]

Originally Posted by fox46

do the specs on that PDF look kosher

Actually, there are a lot of folks here on CD with far more FRC-specific experience. But I have checked FRC's 2012 chart against data I had from past years and the only major error I found so far was the am-0914 data in Line2, which has now been corrected*.

On an earlier thread, Richard indicated he would perform dyno tests on the kit motors and report the results this week. When that data is available, I will incorporate it into the motor calculator.


*edit: but see caveat in post 26 of this thread

[John]

Does anyone know why the stall current for the left handed Denso motor is higher than the stall current for the right handed one? If they are just flipped versions of each other shouldn't they be the same?

[Ether]

Originally Posted by rbrown1

Maybe someone can help me. The Fisher Price motor we have in the kit supplied this year is a 00968-9013. Is there any motor data for this motor available?

A Team Update has just been issued which de-lists the FP2719 and adds the FP9013 as an acceptable motor for 2012.

I would assume that an update to the 2012 motor specs chart* would follow shortly.



* click on the link labeled "data on the motors" on this web page.

[Retired Starman]

Originally Posted by John

Does anyone know why the stall current for the left handed Denso motor is higher than the stall current for the right handed one? If they are just flipped versions of each other shouldn't they be the same?

Driver side window motors are often built heavy-duty since the driver's window gets more use than the passenger window. They are not the same motors.

At least that's how I understand it.

Dr. Bob

Chairman's award is not about building a robot. Every team builds a robot.