View Full Version : Wiring Question
Kalvin1105
09-02-2015, 10:09
Hello i'm Phuc from team 4229. We are using actuators this year and ran into a problem of sorts with getting the actuators to run at the same speed. Does anyone know if it is against the rules to hook up two motors to the same jaguar or talon? I tried looking through the rule book but couldn't find anything about this. Thanks.
Chris_Ely
09-02-2015, 10:10
See rule R42 and Table 4-4 in the Game Manual.
It depends on the type of motor.
If you are using PWM, you can use a splitter cable to send the same signal to two motor controllers.
If you are using CAN, you can set one motor controller to follow the other.
TylerStaudigel
09-02-2015, 10:13
Be sure to check that the amperage that the motors would pull does not exceed the potential output of the jags.
The problem is more likely that the actuators are responding differently to the same input; if this is the case, putting both of them on the same controller wouldn't help. If you really need the two actuators to move in sync, there are two basic solutions:
Hardware. Create a linkage such that the two actuators must always be at the same locations. This would not necessarily need to be as robust as if you were trying to drive things with just one actuator, but it must be good enough to equalize the differences.
Feedback sensors. Whether encoders or string potentiometers, put a sensor on each actuator and adjust the speeds to each so that they move together.
Does anyone know if it is against the rules to hook up two motors to the same jaguar or talon?
R42 clearly covers this topic. "Each power regulating device may control electrical loads per Table 4-4. Unless otherwise noted, each power regulating device may control one and only one electrical load."
Using talon or jag is not one of the exceptions.
R42 clearly covers this topic. "Each power regulating device may control electrical loads per Table 4-4. Unless otherwise noted, each power regulating device may control one and only one electrical load."
Using talon or jag is not one of the exceptions.
According to R42 (second row of table), the following motors may be used with "Up to 2 per controller":
Automotive Window/Door/Windshield
Wiper/Seat Motors
AndyMark PG
Bosch Motor
Snow-Blower Motor
Denso Throttle Control
The list of controllers is R41 (A), and includes both talon, R41(A)(B); and jag, R41(A)(A).
Sperkowsky
09-02-2015, 12:33
Just use 2 talons/jaguars/victors but connect them with one spit pwm cable.
And what are we supposed to assume if our motor doesn't fall into one of those categories? Why doesn't FIRST simply state current or power limitations?
And what are we supposed to assume if our motor doesn't fall into one of those categories? Why doesn't FIRST simply state current or power limitations?
Read Rule R18 (emphasis mine):
The only motors and actuators permitted on 2015 FRC ROBOTS include the following...
If it isn't in the list, you aren't allowed to use it at all.
According to R42 (second row of table), the following motors may be used with "Up to 2 per controller":
Automotive Window/Door/Windshield
Wiper/Seat Motors
AndyMark PG
Bosch Motor
Snow-Blower Motor
Denso Throttle Control
The list of controllers is R41 (A), and includes both talon, R41(A)(B); and jag, R41(A)(A).
Read Rule R18 (emphasis mine):
The only motors and actuators permitted on 2015 FRC ROBOTS include the following...
If it isn't in the list, you aren't allowed to use it at all.
Yikes, so this part is illegal?
http://www.progressiveautomations.com/actuator-linear-actuators-linear-actuator-stroke-size-force-200-lbs-speed-094sec-p-35.aspx
If I'm reading this correctly, we're in pretty big trouble.
the motor on that actuator looks a lot like a CIM. If you can take a legal CIM and stick it on that actuator you are back in action.
The restriction is on the motors we can use not what they are connected to.
Yikes, so this part is illegal?
http://www.progressiveautomations.com/actuator-linear-actuators-linear-actuator-stroke-size-force-200-lbs-speed-094sec-p-35.aspx
If I'm reading this correctly, we're in pretty big trouble.
Many teams have used such COTS linear actuators by replacing the actual motor with one of the motors allowed. In effect, they use the "gearbox" portion of the actuator with an allowed motor. See R18 for the full list - the list above is just the ones which can be duplexed on a single controller. The key things you're going to need to match are shaft, torque, and speed. If you then have several matches, look at mounting options.
Jon Stratis
09-02-2015, 15:11
Yikes, so this part is illegal?
http://www.progressiveautomations.com/actuator-linear-actuators-linear-actuator-stroke-size-force-200-lbs-speed-094sec-p-35.aspx
If I'm reading this correctly, we're in pretty big trouble.
You might need to replace the motor with another legal one, like a CIM or MiniCIM.
Is your team going to be at one of the week-0 scrimmages this weekend? If you let me know which one, I can try to stop by to help at some point and make sure it's legal!
We'll be at the week 0 event at Central High School in Saint Paul
Jon Stratis
09-02-2015, 15:26
Great! Do what you can to make sure it's legal and functional this week, I'll stop by there on my way down to Simley and look for you guys between 8 and 8:30 Saturday morning. Get there nice and early!
Great! Do what you can to make sure it's legal and functional this week, I'll stop by there on my way down to Simley and look for you guys between 8 and 8:30 Saturday morning. Get there nice and early!
Thanks Jon. I'm really at a loss for what we're going to do, so hopefully we get something figured out. The students and one of our mentors are looking at how we can possibly get a CIM motor to engage with this and we are quickly running out of ideas.
Thad House
09-02-2015, 16:00
Thanks Jon. I'm really at a loss for what we're going to do, so hopefully we get something figured out. The students and one of our mentors are looking at how we can possibly get a CIM motor to engage with this and we are quickly running out of ideas.
Do you guys have an actual picture of that device? That motor looks extremely similar to a CIM. are there any part numbers on the motor itself?
No part numbers or anything. Waiting to hear back from the actuator manufacturer to see if they'll give us any details.
Alan Anderson
09-02-2015, 17:14
You might need to replace the motor with another legal one, like a CIM or MiniCIM.
Or a BAG motor. The accessories listed along with that actuator suggest that it doesn't draw more than 10 amps.
In order to put a legal motor on the device, the two things that need to match are the mechanical connection and the speed. If you can determine what the necessary motor speed is, then you're halfway there. For most of the other half, pull the existing motor and figure out what kind of pinion gear, or keying, or flat you need to use in order to drive the rest of the actuator. You should be able to drill some well-placed holes in an adapter plate to mount an appropriate motor where the original one was.
Or a BAG motor. The accessories listed along with that actuator suggest that it doesn't draw more than 10 amps.
In order to put a legal motor on the device, the two things that need to match are the mechanical connection and the speed. If you can determine what the necessary motor speed is, then you're halfway there. For most of the other half, pull the existing motor and figure out what kind of pinion gear, or keying, or flat you need to use in order to drive the rest of the actuator. You should be able to drill some well-placed holes in an adapter plate to mount an appropriate motor where the original one was.
It's a worm gear shaft. Do any approved motors have these?
Jon Stratis
09-02-2015, 17:24
Pull the worm gear off the motor, and see if you have an equivalent sized motor with a similar output shaft you can press the gear onto.
You might need to replace the motor with another legal one, like a CIM or MiniCIM.
The data sheet on the assembled actuator shows a "full load" current of 4.5A at 12V. This sounds like something much smaller than a CIM or even mini-CIM. The BAG or one of the smaller BaneBots or Denso sounds like a closer match. The first step would be to see if you can get a model number on the motor that is in the actuator, and check that against R42. If it's not there, start racking and stacking the motors on the list against the one you found there. You'd probably rather replace it with a more capable motor, but not one that is several times as capable - you'd probably end up shredding some gear teeth inside the mechanism.
PAR_WIG1350
09-02-2015, 17:36
It's a worm gear shaft. Do any approved motors have these?
Depending on the diameter of the worm, you might be able to cut it off and bore it out. Alternatively, if you can figure out the specifications of the worm, you might be able to buy one that can be attached to a shaft. If I misunderstood your post and the worm is not cut into the shaft itself, then you should be able to remove and use that one.
I appreciate all the ideas for help, but we had a veteran 3M engineer, a machinist, myself and 6 kids all scratching our heads on a fix for this. The motor output shaft of the motor on the linear actuator is all worm gear. It doesn't have an attachment to the shaft. It has a diameter similar to the shaft of the CIM motor. I can post pictures tomorrow if anyone wants to take a look at it, but I don't see an easy fix here.
Thanks for all the help and advice.
In answer to your earlier question: Nope, no FRC legal motors have a worm gear output shaft. (All you folks who are going to point out the window motors, that's a spur gear output, not a worm gear output--though they do have worm gears in their gearboxes.)
What I would do, in your shoes, is this: Cut the worm gear off of the motor, as close to the motor as possible, OR better yet replace it with one of the same size and thread and a slightly longer length. (McMaster is your friend, I think.) Machine a coupler, worm gear to motor output, but instead of matching the worm gear tooth on the coupler, just leave that side round and drill a hole through both the coupler and the gear. Drive a pin through the hole and secure it, how is up to you. Now make an adapter to fit your chosen motor to the actuator body. Probably won't take more than a couple of days depending on exact setup and machinist skill/available tools. (You may also be able to find a coupler on McMaster or a similar site.)
Jon Stratis
10-02-2015, 07:47
As Eric said, cut off the output shaft and then do a little work to get it to mate with another motor. If you need access to a lathe, let me know and we can have you over to our build space for an evening. It's important to get that hole dead center!
While you're doing all this, it might be a good time to go back and address your original problem, which was making them both go the same speed. Maybe you could just use the whole shaft and front bearing plate from the existing motors, then add some pulleys to the back ends of the shafts and drive them off the same gearbox with timing belts or light chain.
So I think the option of cutting off the worm gear and attaching it to a legal motor would be the quickest, but more difficult option. This would also involve a lot of work our students couldn't do, which I'm not a fan of.
I think our best option is to find a worm gear of the appropriate size, couple it to a legal motor and get some sort of mounting plate to interface with our actuator. This of course, would all have to be stuff that's done after bagging, given the amount of time left. Jon, I'll send you a PM for your details in case we need to take you up on using your space at all. I think it'd be a great experience if some of my team could come over and see your workspace
Thanks again all.
You could use those pwm splitters that came in the KOP this year. I believe they are brown, yellow, and red wires.
Mbudgery
15-02-2015, 17:32
Hello,
I've searched the internet and some threads but I'm struggling to find a wiring diagram with the encoders and Roborio (pins on encoder vs pins in Roborio). Can someone please share this with us. If someone could reply quickly it would be appreciated. Sorry for asking such a simple question.... Thank you.
Michael
Use 2 DIO channels on the RIO. encoderA goes to signal on one DIO, encoderB goes to signal on the other DIO. encoder ground and power go to ground and power on one of the 2 DIOs.
You could use those pwm splitters that came in the KOP this year. I believe they are brown, yellow, and red wires.
Getting the two PWM signals to match is probably the least likely cause of the problem, (more likely mechanical mismatches or uncalibrated controllers), though I do recall seeing at least one case this year.
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