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The KOP Vex 393 motor being controlled by a black jaguar.
Discussion
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01-02-2012 22:46
CalTran
Re: pic: Gasp!
I thought the Vex 393, along with the motor controller included, would be simply plugged straight into the Digital Sidecar? Would there be an advantage to dedicating a Jag to the 393?
01-02-2012 22:51
akoscielski3
Re: pic: Gasp!
I'm debating whether your "gasping" about the jaguar used for the motor, or that zip ties are connecting them to the electrical board? Is zip ties legal to use as the connectors for the controller??
01-02-2012 22:56
Cecil
Re: pic: Gasp!
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Originally Posted by akoscielski3
I'm debating whether your "gasping" about the jaguar used for the motor, or that zip ties are connecting them to the electrical board? Is zip ties legal to use as the connectors for the controller??
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Normally, for a competition bot, we use 6-32 screws to mount our electronics, but right now on our proto-bot, hundreds of dollars of equipment are mounted with zip ties. It actually saved us once this year: We hit the barrier a little too hard, and the particle board we had everything mounted on broke right under the PD board. If that had been bolted down, it would have most likely cracked the mounting holes on it.
01-02-2012 22:56
JosephC
Re: pic: Gasp!
I can't seem to find anything in the rules about it, but I know your allowed to use zip ties on your robot.
01-02-2012 23:04
CalTran
Re: pic: Gasp!
Our team generally uses 8-32s for our board, but for prototyping we just grab a handful of 1.25" woodscrews, discover they have points on them (ouch), and then use them to secure to wood. I don't think there's anything against the use of zip ties for electronics, but you will have to deal with heavy suggestions to switch to screws or bolts.
01-02-2012 23:14
akoscielski3
Re: pic: Gasp!
Well i know you can use them on your robot... trust me we have containers full of them
just wasnt sure if you could mount stuff that way.
01-02-2012 23:50
Garrett.d.w
Re: pic: Gasp!
Last year we used zip ties to mount out jagwires to our electronics board on the competition robot. Worked great, we never had any problems with anything coming loose. The only reason why we aren't doing it this year is that we are moving from mounting in an inverted "V" formation to a sheet metal tower.
02-02-2012 00:02
vhcook
Re: pic: Gasp!
I've been using zip ties for Jaguar and Spike mounting for years. They work just fine, even under significant impacts. They're light and nonconductive, and they don't vibrate loose. Since the Jaguars weigh 6 oz, and my tub o' zip ties indicates the tensile strength of the medium ones (which I use for this) is 75 lbs, I see no problem. For something like the PDB or cRIO, which has a bit more mass, I'd generally recommend stronger fasteners.
Back on the topic of the picture I'm not sure what benefit you'd gain using a PWM-controlled Jaguar with a Vex motor.
02-02-2012 01:44
Aren Siekmeier
Re: pic: Gasp!
This works? I know for a fact that VEX motors have built in speed controllers that operate off the same signal that the digital sidecar (with a jumper for power). I suppose this would still work just fine since you are giving it a 100% duty cycle signal and just varying the supplied voltage, in effect bypassing the built in speed controller. But what's the point?
02-02-2012 02:09
artdutra04
Re: pic: Gasp!
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Originally Posted by compwiztobe
This works? I know for a fact that VEX motors have built in speed controllers that operate off the same signal that the digital sidecar (with a jumper for power). I suppose this would still work just fine since you are giving it a 100% duty cycle signal and just varying the supplied voltage, in effect bypassing the built in speed controller. But what's the point?
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The old 3-Wire VEX motors had an integrated motor controller and were controlled directly by "servo PWM" pulse and could not be controlled via a Victor or Jaguar speed controller.
The new 2-Wire VEX motors (both the smaller 269 and larger 393 motors, the latter of which were included in the 2012 KOP) are just simple DC motor gearboxes. The are controlled on VEX robots by either directly plugging these into the 2-wire motor ports on the VEX Cortex controller, or by using the Motor Controller 29 (which functions just like a miniature Victor) plugged into a PWM port.
02-02-2012 05:56
AllenGregoryIV
Re: pic: Gasp!
My only question would be is there a risk of damaging the motor running it at 12V+? The VEX system normally runs them off of a 7.2V battery.
02-02-2012 14:43
Lightfoot26
Re: pic: Gasp!
The Digital Sidecar with a power jumper is suppose to supply the correct voltage (7.2, I believe, but don't quote me 
) for the 393, I'm afraid you might damage the motor running it at 12.
02-02-2012 14:59
Aren Siekmeier
Re: pic: Gasp!
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Originally Posted by artdutra04
This is incorrect.
The old 3-Wire VEX motors had an integrated motor controller and were controlled directly by "servo PWM" pulse and could not be controlled via a Victor or Jaguar speed controller. The new 2-Wire VEX motors (both the smaller 269 and larger 393 motors, the latter of which were included in the 2012 KOP) are just simple DC motor gearboxes. The are controlled on VEX robots by either directly plugging these into the 2-wire motor ports on the VEX Cortex controller, or by using the Motor Controller 29 (which functions just like a miniature Victor) plugged into a PWM port. |
02-02-2012 14:59
gpetilli
Re: pic: Gasp!
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Originally Posted by Lightfoot26
The Digital Sidecar with a power jumper is suppose to supply the correct voltage (7.2, I believe, but don't quote me
) for the 393, I'm afraid you might damage the motor running it at 12. |
02-02-2012 20:06
chmconkling
Re: pic: Gasp!
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Originally Posted by akoscielski3
I'm debating whether your "gasping" about the jaguar used for the motor, or that zip ties are connecting them to the electrical board? Is zip ties legal to use as the connectors for the controller??
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02-02-2012 23:43
PAR_WIG1350
Re: pic: Gasp!
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Originally Posted by gpetilli
We are doing the same thing. The 393 data sheet calls it a 7.2V motor with 8.5V max so you are correct to be worried about applying 12V. Assuming you use CAN bus, the Jaguar allows you to set a VMax for lower voltage motors. I dont think i would try this using only PWM input to the Jaguar.
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03-02-2012 00:02
JosephC
Re: pic: Gasp!
We actually tried running vex motors off a 12v supply during OCCRA, blew them out faster then you can believe.
Also, Par_Wig is correct, even setting VMax to 7v killed the motors
03-02-2012 04:54
Jeremy Germita
Re: pic: Gasp!
A little clarification on the picture...
The main point of the picture is that we(the electrical team) thought it would be somewhat humorous to control a Vex motor with a jaguar.
We don't plan on doing anything of this sort, especially after the insight given in this thread. This was merely a little test to see how it would behave.
03-02-2012 08:13
gpetilli
Re: pic: Gasp!
Our breadboard uses two VEX motors, one with the KOP VEX controller tied to a standard PWM output and one tied to a CANJaguar with VMax set to 7V and a 10T Potentiometer for position feedback using the PID (P=250, I=0, D=0) in the Jaguar. Both are working flawlessly. We have not put a scope on the Jaguar output, but we have blown any motors. Your photo is not as crazy as you might think, other than you show using a PWM cable to the Jaguar which may be risky if you command more than +/- 50% percentVolts. Size and weight of the VEX is very attractive for controlling a turret which has a high COG.
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