Using a ramsete controller with pathfinder generated trajectories

Hey everyone,

We have been using pathfinder and have so far liked it. However we would like to use a Ramsete controller instead of the one built in. Is there a way to do this. We have looked at the ramsete equations and the papers but we don’t know how to implement then into the code. If anyone has any tips or can point us to examples on ramsete interpretation that would greatly help.

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We use java by the way

Yes, there is a way to use a Ramsete controller with Pathfinder generated trajectories. Although I would recommend you have some understanding of how to implement it, you can use existing implementations.

One such implementation is actually being PRed to WPILib right now: https://github.com/wpilibsuite/allwpilib/pull/1790

You can get the desired pose, desired linear velocity and desired angular velocity from the Pathfinder paths and substitute those in the controller equations from the PR above. Keep in mind that you’ll need to do odometry to get the current robot pose.

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And differential drive odometry is in yet another PR on track for 2020.

You just have to give DifferentialDriveOdometry encoder and gyro readings and it’ll do the rest to produce current pose.

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Thank you very much. I have odometry working. I have the ramsete controller that uses the differential drive kinematics to return velocities for motors. However, I am not sure how to implement the 2 together. Will replacing the calculated_value in the follow method located in Encoder follower with the ramsete controller work?

I’d have to see the code to know what you mean.

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