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-   -   Encoder (http://www.chiefdelphi.com/forums/showthread.php?t=134838)

nfusselman1 18-02-2015 10:39
Encoder
 
I am needing to know what encoders do we need to buy to put them on the drive train and how would be connect them and program them be have never used them before.

Ether 18-02-2015 11:34
Re: Encoder
 
Quote:
Originally Posted by nfusselman1 (Post 1446338)
I am needing to know what encoders do we need to buy to put them on the drive train and how would be connect them and program them be have never used them before.
Describe your drivetrain in detail (e.g. mecanum or H drive or skidsteer, what gearboxes, etc etc) and what you want the encoders to do for you.

legts 18-02-2015 12:20
Re: Encoder
 
As @Ether said, more details would be appreciated. I programmed the encoders for my team this year but my experience is limited.

nfusselman1 18-02-2015 12:26
Re: Encoder
 
we have the gearbox drive train with the AM14U2 Drive System. (We only use one motor on each side if that helps)

legts 18-02-2015 12:28
Re: Encoder
 
What do you use for speed control (talons, victors, jaguars) and what kind of wheels do you have?

nfusselman1 18-02-2015 12:32
Re: Encoder
 
Talons

nfusselman1 18-02-2015 12:33
Re: Encoder
 
and the regular kit weals (tile)

legts 18-02-2015 12:34
Re: Encoder
 
My team uses jaguars, but the code might be similar. What language do you program in?

nfusselman1 18-02-2015 12:35
Re: Encoder
 
java

legts 18-02-2015 12:45
Re: Encoder
 
What our electrical team did was they wired optical encoders onto the axel and into the jag. Inside of the DriveTrain subsystem, I called a method on each of the jags to inform them that they have encoders. That portion of code looked like this:
Quote:
rightFront.setPercentMode(CANJaguar.kQuadEncoder, encoderCounts);
Below that, I enabled encoder control on each of the jags:
Quote:
rightFront.enableControl();
I was then able to use the encoders in other programs.

I wouldn't know without looking at the javadocs, but if I were to make an educated guess I would say that setting up encoders would be similar to this but with talons instead of jaguars.

nfusselman1 18-02-2015 12:47
Re: Encoder
 
ok what kind of encoders did you get and how did you attach them.

nickmcski 18-02-2015 12:51
Re: Encoder
 
What do you plan to use the encoders for? Making sure both wheels turn at the same speed or are you using it for finding out how far you have driven?

legts 18-02-2015 12:56
Re: Encoder
 
We used optical encoders, I'd have to ask the electrical folks for more details. I'm working on incorporating them into autonomous mode.

nfusselman1 18-02-2015 12:56
Re: Encoder
 
both but mainly distance.

nickmcski 18-02-2015 13:53
Re: Encoder
 
These are the encoders our team purchased http://www.andymark.com/product-p/am-0180.htm and they are working extremely well for us. One thing we want to try is wiring them directly up to our talons (You can only do this if you have the talon SRX's).

If you cant wire them up to the talons then wire them up to the roboRIO, our team accomplished this by cutting up 2 unneeded PWM cables. We wired the cables like so:


(This image is not mine, I just found it online)

Then we programmed them link this
Code:
        Encoder encoderleft; //Declare the encoders so they are accessible in all methods
        Encoder encoderright;

        public void robotInit() {
                encoderleft = new Encoder(0, 1); //Initalize the encoder, A channel is plugged into DIO 0, B channel DIO 1.
                encoderright = new Encoder(2, 3);

                encoderleft.setDistancePerPulse(0.11); //did some math to calculate that for 1 pulse the robot moved 0.11 of an inch (Will be different for other robots)
                encoderright.setDistancePerPulse(0.11);
        }

        public void autonomousPeriodic() {
                double distance = (encoderleft.getDistance() + encoderright.getDistance()) /2; //Find the distance robot has travled based off of the average of the 2 encoders.
               


                //Code to make your robot move off of the encoder values here
        }

GeeTwo 18-02-2015 16:13
Re: Encoder
 
Quote:
Originally Posted by nickmcski (Post 1446459)
We wired the cables like so:


(This image is not mine, I just found it online)
The encoders should be connected to DIOs, not PWM ports!

Ether 18-02-2015 16:24
Re: Encoder
 
Quote:
Originally Posted by GeeTwo (Post 1446542)
The encoders should be connected to DIOs, not PWM ports!
Yes, I agree, that diagram can be misleading out of context. The "PWM" in the diagram refers to the use of PWM cable/connectors.

In context (i.e. on the web page where the diagram came from) it explicitly says to connect the cable to DIO ports.

Fauge7 18-02-2015 17:41
Re: Encoder
 
is there any reason why i wouldnt get an accurate reading from the encoders?

Ether 18-02-2015 17:51
Re: Encoder
 
Quote:
Originally Posted by Fauge7 (Post 1446608)
is there any reason why i wouldnt get an accurate reading from the encoders?
To avoid having two separate conversations about two unrelated questions in the same thread, it would be best if you started a new thread if your question is not related to the OP's question; and provide more detail about the problem you are experiencing.

NathanCJohnson 19-02-2015 15:28
Re: Encoder
 
Quote:
Originally Posted by nickmcski (Post 1446459)
These are the encoders our team purchased http://www.andymark.com/product-p/am-0180.htm and they are working extremely well for us. One thing we want to try is wiring them directly up to our talons (You can only do this if you have the talon SRX's).

If you cant wire them up to the talons then wire them up to the roboRIO, our team accomplished this by cutting up 2 unneeded PWM cables. We wired the cables like so:


(This image is not mine, I just found it online)

Then we programmed them link this
Code:
        Encoder encoderleft; //Declare the encoders so they are accessible in all methods
        Encoder encoderright;

        public void robotInit() {
                encoderleft = new Encoder(0, 1); //Initalize the encoder, A channel is plugged into DIO 0, B channel DIO 1.
                encoderright = new Encoder(2, 3);

                encoderleft.setDistancePerPulse(0.11); //did some math to calculate that for 1 pulse the robot moved 0.11 of an inch (Will be different for other robots)
                encoderright.setDistancePerPulse(0.11);
        }

        public void autonomousPeriodic() {
                double distance = (encoderleft.getDistance() + encoderright.getDistance()) /2; //Find the distance robot has travled based off of the average of the 2 encoders.
               


                //Code to make your robot move off of the encoder values here
        }
Does that encoder work with the 2015 KOP chassis gearboxes? The video tutorial on the item page shows a different gearbox, so I just want to make sure it works with the KOP one.

We should have added encoders a while ago before bag & tag, but since we didn't we will be adding them during the 6-hour robot access period the week of our first district event. Currently our autonomous modes are based on a timer which isn't very accurate or predictable.

Ether 19-02-2015 15:56
Re: Encoder
 
Quote:
Originally Posted by NathanCJohnson (Post 1447173)
Currently our autonomous modes are based on a timer which isn't very accurate or predictable.
What kind of drivetrain do you have?



nickmcski 19-02-2015 16:12
Re: Encoder
 
Quote:
Originally Posted by NathanCJohnson (Post 1447173)
Does that encoder work with the 2015 KOP chassis gearboxes? The video tutorial on the item page shows a different gearbox, so I just want to make sure it works with the KOP one.

We should have added encoders a while ago before bag & tag, but since we didn't we will be adding them during the 6-hour robot access period the week of our first district event. Currently our autonomous modes are based on a timer which isn't very accurate or predictable.
Our team didn't get the KOP drive train but on andymarks website they say that the KOP gearbox is compatible with the type of encoders I linked.

Here is the information about the gear box if you want to look at its specification for the encoders http://www.andymark.com/product-p/am-2598.htm

Fauge7 19-02-2015 17:41
Re: Encoder
 
Quote:
Originally Posted by nickmcski (Post 1447206)
Our team didn't get the KOP drive train but on andymarks website they say that the KOP gearbox is compatible with the type of encoders I linked.

Here is the information about the gear box if you want to look at its specification for the encoders http://www.andymark.com/product-p/am-2598.htm
yeah are they compatible? my team ran into the same problem...they are mounted but it seems they are not giving us a very reliable rate

NathanCJohnson 19-02-2015 21:55
Re: Encoder
 
Quote:
Originally Posted by Ether
What kind of drivetrain do you have?
We're using the one that came in the Kit of Parts (http://www.andymark.com/AM14U2-p/am-14u2.htm). But we're using 6" traction wheels in the front and 6" omniwheels in the back (the middle wheels are the 4" wheels that came with the KOP drivetrain).

NathanCJohnson 19-02-2015 21:59
Re: Encoder
 
Quote:
Originally Posted by nickmcski (Post 1447206)
Our team didn't get the KOP drive train but on andymarks website they say that the KOP gearbox is compatible with the type of encoders I linked.

Here is the information about the gear box if you want to look at its specification for the encoders http://www.andymark.com/product-p/am-2598.htm
Alright, thanks! I think we'll order a couple (hopefully they'll come fast enough) and we can add them during the robot access period and get autonomous working with them.

Ether 19-02-2015 22:10
Re: Encoder
 
Quote:
Originally Posted by NathanCJohnson (Post 1447374)
we're using 6" traction wheels in the front and 6" omniwheels in the back (the middle wheels are the 4" wheels that came with the KOP drivetrain).
Are you powering all 6 wheels? How?

NathanCJohnson 19-02-2015 23:53
Re: Encoder
 
Quote:
Originally Posted by Ether (Post 1447385)
Are you powering all 6 wheels? How?
Two CIM motors power the gearbox which moves the middle wheel. The front and rear wheels are powered by the middle wheel with belts. We use tank drive to actually drive and steer it.

Ether 19-02-2015 23:56
Re: Encoder
 
Quote:
Originally Posted by NathanCJohnson (Post 1447439)
Two CIM motors power the gearbox which moves the middle wheel. The front and rear wheels are powered by the middle wheel with belts.
You said the middle wheels are 4" and the front/back are 6". Have you geared them in the proper 6:4 ratio so they are going the same tangential speed?

GeeTwo 22-02-2015 01:32
Re: Encoder
 
Quote:
Originally Posted by NathanCJohnson (Post 1447374)
We're using the one that came in the Kit of Parts (http://www.andymark.com/AM14U2-p/am-14u2.htm). But we're using 6" traction wheels in the front and 6" omniwheels in the back (the middle wheels are the 4" wheels that came with the KOP drivetrain).
Quote:
Originally Posted by Ether (Post 1447443)
You said the middle wheels are 4" and the front/back are 6". Have you geared them in the proper 6:4 ratio so they are going the same tangential speed?
Unless the chassis has been modified (drilled more holes) it isn't necessary. The center axle on the AM14U2 is only dropped 1/8". Since the corner wheels are 2" larger diameter, the 4" center wheels float 7/8" off the carpet. In effect, the 4" wheels are just a spacer for the belt sheaves.

We did something similar with our H-drive, though since we used 4" wheels on the corners, we cut the rubber off the center wheels so they would float.

Ether 22-02-2015 08:52
Re: Encoder
 
Quote:
Originally Posted by GeeTwo (Post 1448190)
the 4" center wheels float 7/8" off the carpet.
Except when going over the platform.

GeeTwo 22-02-2015 09:44
Re: Encoder
 
Quote:
Originally Posted by Ether (Post 1448226)
Except when going over the platform.
Yes, that would be a literal speed bump.


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