Large motor with Propeller Robot Control Board?

modemman

Is it possible to drive motors such as the FIRST CIM Motor (12v, 2.7A no load, 133A stall) with the Propeller Robot Control Board directly? I assume the board will overheat and blow up. No radiator/cooling? Then again, it's better to ask people who know stuff (aka the good people of this forum).

I intended to use one HB-25 for each motor, but then noticed this board has a dual-bridge controller - that would save money/space, etc. What's the difference between "no load", "load" "stall" and other specs used to describe DC motors?

Thanks.

Timmoore

no load is when there is nothing attached to the motor, i.. it just has to spin itself. stall is when there is so much load the motor stops - normally a bad idea to run a motor like this though the CIM does handle abuse like this better than most but its still not a good idea.
So no the drivers on the control board will not run the CIM without overloading. The HB-25 will run it as long as you dont have a lot of load on the CIM the HB-25 can supply 25A, the CIM can take 133A - i.e. more than the HB-25 can supply. I use the CIMs with controller that can supply 40A with spikes to 100A and a fuse that is auto reset but with the HB-25 you will probably blow the fuse on it often.

Mike Green

"No load" means the motor is spinning freely at roughly constant speed and no load on it (other than the friction of the bearings).

"Load" doesn't mean anything by itself. The mechanical load has to be specified.

"Stall" means that the motor is prevented from rotating through friction or, if it's driving a wheel, by a sufficient incline and weight that it can't turn

Without a load and at constant speed, the motor is drawing the minimum current possible.

Stalled, the motor is drawing the maximum current possible. Commonly, the motor, controller, and power source are not designed to handle the stall current for more than a fraction of a second or a few seconds at most without damage from overheating. Hopefully, there's a fuse or circuit breaker that will shut everything down before damage occurs.

Maximum intermittent current for the HB-25 is 35A. Maximum current for the bridge on the robot control board is 2.8A. You could probably use the HB-25 if you fuse the circuit at 25A. There's no way you could use the robot control board's bridge for this size motor.

modemman

Got it. So I'm always looking at the max. of all currents, basically from normal load, to heavy load, to stall.... The robot board goes kaboom after 2.8Amps, the HB-25 blows a fuse after 25 Amps... I'll definitely torture the CIMs, since they'll have to accelerate and carry fat people (making a scooter thingy), so I should look into some heavy duty controllers. Any specific one that the propeller community loves most?

Thanks again.

Timmoore

I have used the controllers that FIRST use for driving CIMS, both as part of FIRST and for my own use. There are 2

http://www.vexrobotics.com/products/vexpro/victor-speed-controller.html

http://www.luminarymicro.com/jaguar·(you can get it from digikey)

They both can use pwm to control which the prop can generate, I haven't had any problems with either.

Neither is particular cheap.

W9GFO

I have used the HB-25s with a 150 lb robot that uses wheel chair motors. I can tell you that they will go into shutdown if you try to accelerate too fast. I am not familiar with the motors you mentioned but I would expect that the HB-25s are not capable of supplying the current that you need to "accelerate fat people".

VanTec is popular, Dimension Engineering seems okay and then there is the OSMC

Rich H

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The Simple Servo Tester, a kit from Gadget Gangster.

jamma

I second the suggestion of the Victors (Vex/IFI) for a motor that size, although the Sidewinder from RobotPower is also interesting. Have a look here for a fairly comprehensive list of non-Parallax motor control options:
www.robotmarketplace.com/products/speed_controllers_main.html

Peter KG6LSE

I just used a VexPro Victor 884 in a RC Power Wheels ,IMHO its worth it

FIRST 294 ..BCR


Peter KG6LSE

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"Carpe Ducktum" "seize the tape!!"
peterthethinker.com/tesla/Venom/Venom.html
Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway. —Tanenbaum, Andrew S.
LOL

modemman

Thanks a lot guys, very informative. I'm just entering a very new world (for me) of high power / high amperage, which is less forgiving than the small bot / servo world. I just did my reading based on your suggestions and now I understand the principles.

I'll probably stick with a pair of Victor 884, for price, size and ruggedness reasons. The Jaguars look very sophisticated, but I won't be using most of the features, and, more importantly, they're quite large. I also looked at the OSMC, Sabretooth 2x50HV and a few others that are probably awesome, but too expensive for me.

I'm also getting a 100 or 120A breaker and a fuse box. Toying with the idea of using a separate battery pack for the controller board (I spent a lot of time setting up a 5DOF IMU on a standard prop dev board and I don't want to fry any of it) or go with a set of extra fuses / breakers / polyswitches and pull from the big 12V pack... This is definitely a bit different from the 3.3/5V stuff I was used to! I guess I'll learn about good old electricity in the process...

Thanks again!