SIM MOTOR Encoders? [Archive]

Bluejackets

23-12-2015, 11:20

marshall

23-12-2015, 11:23

Our team has a goal this year to learn and use encoders and use them during autonomous. We having been looking at andymark and are confused what ones to get. Also we are programming in C++

We would like to use encoders on our drive SIM motors. Any suggestions or what type to get? Also if you have a good source we are not sure where to buy as well. Thanks for your time and help.

Bluejacket Robotics

We really liked the CUI encoders this past year.
http://firstchoicebyandymark.com/fc16-029

Prior to that we have used these:
http://www.andymark.com/product-p/am-3132.htm

New for this year are these and we beta tested them. They work great:
http://www.ctr-electronics.com/srx-magnetic-encoder.html

Bluejackets

23-12-2015, 11:32

Thanks for the links. We are very new to encoders. Do all of these fit onto the drive shaft of a SIM Motor or do they attach somewhere else.

Are there any installation instructions anywhere or diagrams out there specifically for encoders on a SIM.

E Dawg

23-12-2015, 11:35

What motor controllers are you using? If you are using Talon SRX's, you will want to pick up some of these in addition to your encoders: http://www.vexrobotics.com/217-4398.html

This will make using the encoders much easier. Of course, this doesn't matter if you are making use of another controller.

PS: It's CIM, not SIM. ;)

GeeTwo

23-12-2015, 11:37

Except on motors with a backshaft (like the AndyMark PG series), the selection of encoders will depend on your gear train, not on the motor. After you've determined what gearbox you'll be using (or building), you will have a somewhat smaller set of encoders to consider (or a possibly more difficult job of mounting them). Encoders are usually mounted at the slow end of the drive train (wheel axle), not the fast end (motor shaft).
For items with a limited travel distance (arms and lifts, not wheels), you may want to consider potentiometers rather than encoders - they're usually less expensive, inherently absolute rather than relative, and a bit more straightforward to code.

Knufire

23-12-2015, 12:28

Thanks for the links. We are very new to encoders. Do all of these fit onto the drive shaft of a SIM Motor or do they attach somewhere else.

Encoders rarely attach directly to the motor, they usually mount somewhere on the gearbox that the motors are mounted to.

Are you planning on using the kit of parts drivetrain? If you are, this is going to be what you want: http://www.andymark.com/product-p/am-3132.htm.

That kid includes an encoder, the cable that attaches to it, and everything you'll need to mount it. Note that this cable has the encoder connection on one end and bare leads on the other end. If you're not comfortable crimping PWM connectors on the other end, feel free to get two of this cable as well: http://www.andymark.com/product-p/am-2269.htm

Mounting instructions can be found here: http://cdn.usdigital.com/assets/assembly/E4T%20Assembly%20Instructions.pdf. The encoder mounts to two small holes on the motor side of the plastic casing, with the back of the output shaft going into the encoder.

jijiglobe

23-12-2015, 13:52

New for this year are these and we beta tested them. They work great:
http://www.ctr-electronics.com/srx-magnetic-encoder.html

Is there anywhere we can find a spec sheet for these encoders? (SRX MAG) Something with dimensions and mounting geometry?

marshall

23-12-2015, 13:53

Is there anywhere we can find a spec sheet for these encoders? (SRX MAG) Something with dimensions and mounting geometry?

Check the "tech resources" tab at the bottom of the page.

GeeTwo

23-12-2015, 18:53

Also, for a lot of neat info about sensors in general, with info on encoders, see this thread (http://www.chiefdelphi.com/forums/showthread.php?t=140544) started today.

Bluejackets

23-12-2015, 19:42

We appreciate all your time and help! Have a great holiday season and go teams!

GeeTwo

30-12-2015, 23:13

SHAZAM! There are now CIM motor encoders (http://www.andymark.com/encoder-p/am-3314.htm) available on AndyMark. You may have difficulties finding gearboxes that can engage the CIM through this "spacer". Those mounting CIMs and minCIMs to Versaplanetaries were complaining about too-long shafts, so perhaps these encoders could kill two birds with one stone in that application.

rsisk

31-12-2015, 07:42

SHAZAM! There are now CIM motor encoders (http://www.andymark.com/encoder-p/am-3314.htm) available on AndyMark. ...[snip]

Pull up resistors are necessary to generate an output signal for the desired voltage level

For us folks lacking such electrical knowledge, could someone comment on what this means? I checked the spec sheet, but it was not much help.

marshall

31-12-2015, 08:27

For us folks lacking such electrical knowledge, could someone comment on what this means? I checked the spec sheet, but it was not much help.

You need to connect resistors (would go with 10k) between the quadrature lines and the +5v rail. This will pull the signal to high when not being actively pulled low by the encoder. If you don't do this then you're going to get some noise.

EDIT: Section 1.4.3 of the Talon SRX User Guide has a diagram: http://www.ctr-electronics.com/Talon%20SRX%20User's%20Guide.pdf

Thanks Omar!

GeeTwo

31-12-2015, 08:29

For us folks lacking such electrical knowledge, could someone comment on what this means? I checked the spec sheet, but it was not much help.

On the specifications sheet (http://files.andymark.com/PDFs/CIMcoderSpecSheet.pdf), at the bottom left on page 2 is a schematic showing how to wire these resistors. The sentence simply means that these resistors and the connection of them to supply voltage is not done internally to the encoder. This means that if you don't use pull up resistors, when the output signal is supposed to be high, it will instead be open (connected to nothing).

If you connect this encoder to two of the DIO ports on the RoboRIO, this will not be necessary as those pull up resistors are implemented inside the RIO. I haven't checked the internal wiring of the various motor controllers which support encoders (Jaguar, SRX) to see if they have this resistor internally or not; from the comment, I suspect that at least one of them does not.