[FTC]: Motors

[xyz]

Are we only allowed 3 extra motors this year besides the drive motors?

So if we four wheel drive, and use all four drive motors... we only have 3 left?

[Akash Rastogi]

You don't need to use all four for 4wd. Depending on your design I'd say that'd be wasting motors. These have higher torque and also power so I'd be careful with what you decide as a design if I were you.

Good thing to do would be draw out a few different DT designs and find one that gives you more pushing power this year and not worry about speed so much.

Best of luck.

[smartkid]

Your allowed 13 motors:

- 4 DC
- 6 Servos (which may be continuous, not sure)
- and 3 lego motors

[Lowfategg]

Every motor in the kit is allowed. You can't add anymore.

[dickswan]

I don't have a kit but last time I looked at the parts list, it contained:
- 4 of the 12V DC motors.
- 2 motor encoders for these motors
- 1 HiTechnic motor controller equipped with two motor control outputs and two motor encoder inputs.

One way to control four 12V motors with one HiTechnic controller is to attach two motors to one output. This is what many teams did for the pilot trial. Only equip one of the motors with an encoder and connect it to the appropriate input on the controller.

A second way to control four motors is to purchase a second HiTechnic controller. There was discussion about allowing purchase of a second HiTechnic controller although I'm not sure how this finally worked out. Currently I can't find them for sale on the web.

All three software programming environments should work whether or not the motors are actually equipped with encoders. If not equipped, then some of the more power motor commands -- e.g. "move motor 5000 encoder counts", "move motor at precise speed using feedback from encoder" -- are lost.

[JesseK]

On the subject of motors, does anyone more specs on the motors? Specifically I'm looking for current draw specs -- Stall Current and Free Speed Current. Here's what I have so far:

Stall Torque = 300 oz-in = 2.12 N*m (slightly less than a CIM)
Free Speed = 152 RPM

This is all gravy for figuring out how fast a drive train goes, but not good enough to figure out if the motors will survive pushing match after pushing match. Then there's the question of how hard you're straining the motors by lifting the robot arm with some weight at the end of it. Anyone?

[gblake]

Originally Posted by JesseK

On the subject of motors, does anyone more specs on the motors? Specifically I'm looking for current draw specs -- Stall Current and Free Speed Current. ...

Does this info from Robert May and on the LynxMotion site match up with the Type and Model number of the motors that were actually shipped with the kits? - If so, I think you can get most if not all of what you want from it. Robert dug it up back in March for the teams that were prepping for the "Showcase Tournament".
**********************************************

Thursday, March 20, 2008
Gearhead motor specs
For those interested, I was able to find the following specs along with the posted link to a data sheet for the Hsiang Neng motors.

Model= HN-GH12-2413T
Weight = 7.15 oz
Reduction = 50:1
Stall Torque = 231.5 oz-in
Length (motor and gear) = 2.33" (5.92 cm)
Length (shaft only) = 0.89" (2.26 cm)
Diameter (motor and gear) = 1.45" (3.68 cm)
Diameter (shaft) = 6mm
Outside Diameter = 37mm
Current (at 12v no load) = 145mA
Current (at 12v locked shaft) = 3.8A

http://www.lynxmotion.com/images/data/ghm13.pdf
Posted by Robert May at 4:12 PM

**********************************************
Blake