Running Commands during Autonomous

Important

This documentation describes the use of the legacy command-based library. While this documentation has been preserved to help teams that have yet to do so, teams are strongly encouraged to migrate to the new command-based library.

Note

Once commands are defined they can run in either the teleop or autonomous part of the program. In fact, the power of the command based programming approach is that you can reuse the same commands in either place. If the robot has a command that can shoot Frisbees during autonomous with camera aiming and accurate shooting, there is no reason not to use it to help the drivers during the teleop period of the game.

Java

C++

public class SodaDelivery extends CommandGroup {

    public  SodaDelivery() {
      addSequential(new PrepareToGrab());
      addSequential(new Grab());
      addSequential(new DriveToDistance(0.11));
      addSequential(new PlaceSoda());
      addSequential(new DriveToDistance(0.2));
      addSequential(new Stow));
    }
}

#include "PlaceSoda.h"

PlaceSoda::PlaceSoda()
{
    AddSequential(new PrepareToGrab());
    AddSequential(new Grab());
    AddSequential(new DriveToDistance(0.11));
    AddSequential(new PlaceSoda());
    AddSequential(new DriveToDistance(0.2));
    AddSequential(new Stow());
}

Our robot must do the following tasks during the autonomous period: pick up a soda can off the floor then drive a set distance from a table and deliver the can there. The process consists of:

1. Prepare to grab (move elevator, wrist, and gripper into position)

2. Grab the soda can

3. Drive to a distance from the table indicated by an ultrasonic rangefinder

4. Place the soda

5. Back off to a distance from the rangefinder

6. Re-stow the gripper

To do these tasks there are 6 commands that are executed sequentially as shown in this example (note that some of these, such as PlaceSoda are other command groups).

Setting the Command to Run during Autonomous

Java

C++

public class Robot extends TimedRobot {
    Command autonomousCommand;

    /**
     * This function is run when the robot is first started up and should be
     * used for any initialization code.
     */
    public void robotInit() {
      oi = new OI();
        // instantiate the command used for the autonomous period
        autonomousCommand = new SodaDelivery();
    }

    public void autonomousInit() {
        // schedule the autonomous command (example)
        if (autonomousCommand != null) autonomousCommand.start();
    }

    /**
     * This function is called periodically during autonomous
     */
    public void autonomousPeriodic() {
        Scheduler.getInstance().run();
    }

Command* autonomousCommand;

class Robot: public TimedRobot {

    /**
     * This function is run when the robot is first started up and should be
     * used for any initialization code.
     */
   void RobotInit()
   {
        // instantiate the command used for the autonomous period
      autonomousCommand = new SodaDelivery();
      oi = new OI();

   }


   void AutonomousInit()
   {
        // schedule the autonomous command (example)
      if(autonomousCommand != NULL) autonomousCommand->Start();
   }
   /*
    * This function is called periodically during autonomous
    */
   void AutonomousPeriodic()
   {
      Scheduler::GetInstance()->Run();
   }

To get the SodaDelivery command to run as the Autonomous program,

1. Instantiate it in the RobotInit() method. RobotInit() is called only once when the robot starts so it is a good time to create the command instance.

2. Start it during the AutonomousInit() method. AutonomousInit() is called once at the start of the autonomous period so we schedule the command there.

3. Be sure the scheduler is called repeatedly during the AutonomousPeriodic() method. AutonomousPeriodic() is called (nominally) every 20ms so that is a good time to run the scheduler which makes a pass through all the currently scheduled commands.