Welcome to the motion control repository of the FRC team #4590. The repository was opened in the 2018 season and is being worked on and improved every season.
This project relies upon jitpack in order to implement itself inside other projects.
In order to add this project you will need to use gradle. In your build.gradle file you should add the section:
repositories {
jcenter()
maven { url "https://jitpack.io" }
mavenCentral()
}
And alongside that, in your dependencies section add the line:
compile 'com.github.GreenBlitz.MotionControl:motion:master-SNAPSHOT'
This should add the most recent release of the software into your project. In case this results
in issues, try to replace the master-SNAPSHOT part with the hash the the most recent commit (If you
do it that way, you will need to update the hash manually).
The repository contains an implementation of the pure pursuit algorithm. The algorithm requires to know the
current location of the robot, and for that a Localizer class is supplied.
The Localizer will calculate the movement of the robot when given the amount of meters each side of
the chassis has covered since the last encoder reset. It is optionally possible to pass an angle to the
algorithm (for example from a gyro sensor) but if no angle is passed the algorithm will calculate the angle
on its on (note that this may be less accurate).
The localizer has been tested thoroughly and was shown to be accurate enough for the APPC to work. Non the less it is still recommended to use an angle value from an external sensor such as a gyro.
As with all of our features, the localizer is in essence just a collection of commands, and the use of those command in the robot code is left as a decision for the user.
The paths supplied to the APPC are simple lists of Point objects. It is recommended to generate the paths
with an external tool such as PathWeaver.
The controller object is essentially an interface of commands, out of which the most essential command to the
user is iteration(T robotLocation). This function returns a double array who's first value is the power
you need to supply to the left motor and the second value is for the right motor.
Using this command you can easily incorporate the calculation of the controller into your main robot loop.
TODO
A 1 dimensional motion profile can be generated for any actuator. The profile can be
generated using Profiler1D that returns a MotionProfie1D. In order to do so, supply the
profiler with a set of actuator locations which are waypoints for your actuator. Each
actuator location contains a location (a number, because there is 1 dimension) and the velocity
of the actuator. Of course you will also need to supply maximum velocity and acceleration of
your actuator.
The generated profile will pass through all the locations, at the given speeds, as fast as physically possible. Note that the profile is continuous, and you can get the desired velocity, acceleration and position of the actuator at any point in time.
- No external forces affect the actuator location, if they do (e.g. elevator) then you will need a custom profiler.
- The jerk is infinite. This is a safe assumption for most cases, as we have found through testing that the jerk is always at least 2 orders of magnitude larger than the acceleration and therefor can be neglected.
- No need to run the code at a constant speed, any speed fast enough will work. Also, this eliminates errors that happens when your code does not run at the exact cycle speed needed for some discrete profiles.
- Small amounts of memory taken for much higher accuracy. Since only segments of equal acceleration are saved, you can have as little as 3 segments (each is an object with 5 doubles) for the whole profile. Despite the small amount of saved information, the data saved within it is more accurate then any discrete set of points.
TODO
TODO