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 Chief Delphi Swerve Control Algorithm
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#1
12-06-2018, 10:26 PM
 sthump Registered User AKA: Elmer Lee FRC #5205 (Full Metal Jackets) Team Role: Mentor Join Date: Feb 2017 Rookie Year: 2016 Location: Michigan Posts: 64
Swerve Control Algorithm

Do most teams simply use pure PID to control their swerve drives? Or is there something more? Do teams use velocity and acceleration following? If so, how do you generate the profiles on the fly as the driver is continuously changing the heading?

If anyone can provide any technical pointers I would really appreciate it.

Thanks

Elmer
#2
12-07-2018, 02:25 AM
 PatrickW Engineering Mentor AKA: Patrick Woolfenden FRC #2910 (Jack in the Bot) Team Role: Engineer Join Date: Jun 2017 Rookie Year: 2009 Location: Mill Creek WA Posts: 100
Re: Swerve Control Algorithm

For teleop driving, the target angle and drive power each wheel gets are usually determined with some vector math based on the joystick inputs. One joystick for translation and one for rotation. PID is used to steer the wheels to their target angle. So no motion profiling on the fly or velocity or acceleration targeting. I think this is how most teams are doing it still.

When coding our swerve we found Ether's swerve kinematics papers really helpful. This one in particular gets strait to the point including field oriented calculations.
__________________

COTS Swerve Modules: SwerveDriveSpecialties.com
#3
12-07-2018, 11:33 AM
 sthump Registered User AKA: Elmer Lee FRC #5205 (Full Metal Jackets) Team Role: Mentor Join Date: Feb 2017 Rookie Year: 2016 Location: Michigan Posts: 64
Re: Swerve Control Algorithm

We have the inverse kinematics down. Ether's publishings were immensely informative and helpful. Thanks Ether.

We are having a lot of variable friction and thus PID tuning is proving to be really challenging.

I've concluded that velocity and acceleration following is the only way to get it done if at all.

We are working on a differential swerve drive design -

https://www.chiefdelphi.com/forums/s...32#post1781432

It feels like we have too much speed and not enough speed control resolution to be able to respond to the friction variations.

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