Project Link
Pathfinder is an API for Motion Profiling. Give it a few waypoints and some information about your Robot and it will generate a nice smooth trajectory for your robot to follow to avoid jerkiness and keep your robot's autonomous movements accurate.
Pathfinder can generate paths for both Tank and Swerve drive systems, as shown in the images below:

(red = front wheels, blue = back wheels. Drivebase constantly facing forward)
Pathfinder's actual generation code is all written in C, so it's very fast, meaning profiles can be generated on the fly. Pathfinder supports C, C++ and Java currently, and doesn't have any dependencies! Because it doesn't have any dependencies, you can even use it in your non-frc projects if you want to.
Pathfinder can use any type of encoder as a feedback device to keep your robot on track. All the parameters are exposed, so you can run the control loop at any speed you like.
The
wiki contains instructions for setup and some demo code for generation and following in both Java and C++.
If you use Toast, it will also work in simulation if you're running Windows or Mac. If you're on linux, you can build and install the library manually with the instructions in the readme.
Special thanks to Austin Schuh, Jared Russel and Tom Bottiglieri for pioneering motion profiling code in FRC, and for giving
this wonderful talk. Some of the generation code was inspired by Team 254's 'TrajectoryLib', although heavily modified to be more efficient and to work in C.