Encoder Help

[Ether]

Originally Posted by Team5709

Hello everyone! I was wondering how I would use encoders to figure out how far our robot would drive in autonomous? A big thanks in advance for those who are willing to help.

Answer these questions and you may get more detailed help:


what is the part number of the encoders

how are the encoders wired [roboRio or SRX]

where are the encoders mounted

what is the gear ratio between encoder and wheel

what kind of drivetrain are you using

what is wheel diameter

what model motor controllers are you using

are you using PWM or CAN bus

[GeeTwo]

If you haven't made any of the decisions yet about what encoders to use and need help with THAT, knowing the specifics of your gearbox (make and model type stuff) as well as the other things Ether mentioned that you DO know will help in getting those answers.

[TylerHarmon]

Originally Posted by Ether

Answer these questions and you may get more detailed help:


what is the part number of the encoders

how are the encoders wired [roboRio or SRX]

where are the encoders mounted

what is the gear ratio between encoder and wheel

what kind of drivetrain are you using

what is wheel diameter

what model motor controllers are you using

are you using PWM or CAN bus

Exactly! This information is important to solving the problem that you have. Jumping headfirst into a problem like "How can I make the robot drive 5 feet with encoders" can be daunting, so you should break it down into simpler pieces first

[Team5709]

Encoder: Encoder Kit AMT103-V (fc17-033)

they will be wired into the RoboRio. They are mounted on the out put shaft of the drive gear boxes. one on the left and one on the right. There is no gear ratio because its on the out put shaft and not on the motor it self. We are gonna be using arcade drive. The wheels are the 6 inch wheels (http://www.andymark.com/HiGrip-Wheel...?1=1&CartID=0). The motor controllers we are using are the 2015 Talon KOP controllers and those are using PWM.

[euhlmann]

Originally Posted by Team5709

Encoder: Encoder Kit AMT103-V (fc17-033)

they will be wired into the RoboRio. They are mounted on the out put shaft of the drive gear boxes. one on the left and one on the right. There is no gear ratio because its on the out put shaft and not on the motor it self. We are gonna be using arcade drive. The wheels are the 6 inch wheels (http://www.andymark.com/HiGrip-Wheel...?1=1&CartID=0). The motor controllers we are using are the 2015 Talon KOP controllers and those are using PWM.

Check out the screensteps reference: http://wpilib.screenstepslive.com/s/...or-other-shaft

And check out how to configure your encoder's pulses per revolution on the datasheet, page 4 http://www.cui.com/product/resource/amt10.pdf
Keep "maximum rpm" in mind when choosing a value. Choose the highest number of ticks that fits your intended rpm for the best accuracy.

Then you can get distance like this

Encoder enc = // create encoder as per screensteps
int ticksPerRev = // what you set them to
double diameter = 6.0; // inches
double distancePerRev = diameter * Math.PI;
enc.setDistancePerPulse(distancePerRev / ticksPerRev);

// later
double currentDistance = enc.getDistance(); // in inches

Edit: I'm unfamiliar with the 2015 KOP, but if those are Talon SRX controllers, you're a lot better off using CAN than PWM, because you can connect the encoders directly to Talons for high rate PID control.