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Curriculum challenge ~ Altering Tank Drive

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Alex Schokking edited this page Jul 15, 2022 · 2 revisions

Table of Contents

Introduction

At this point you now have a basic robot that can be driven around with a set of 2 joysticks using tank drive. Next we're going to augment that basic drive system to support a whole range of new pieces of functionality.

Note about 'buttons'

For the commands in this list, you can just focus on implementing the command itself. Don’t worry about mapping the commands to buttons, the unit tests will just run your command directly. Later on you'll learn how to do the button->command mapping.

Features to add

Precision Drive:

  • Command you'll be filling in: TogglePrecisionDriveCommand (this file already exists - find it under xbot->subsystems->drive->commands)
  • Unit test: TogglePrecisionDriveCommandTest
When the driver presses a button (which invokes your command), all robot power is reduced by 50%. When they press this button again, power returns to 100%. This is useful when the driver needs to be able to make precise, small motions with the robot.

Example: User has left joystick at 100% forward. The left motors are outputting 100% forward power. User then presses the joystick button while holding joystick forward. The left motors should now be outputting 50% power.

Hints:

  • We want to modify the behavior of the DriveSubsystem until this method is called again. This means we'll need to use TogglePrecisionDriveCommand to save some information into the DriveSubsystem every time .

Arcade Drive (Advanced)

  • Command: ArcadeDriveWithJoysticksCommand
  • Unit test: ArcadeDriveTest
Arcade drive is an alternative scheme for controlling our robot. Instead of using 2 joysticks where we only use the y-axis of each, with arcade there is only one joystick and we use this for both forward/backward as well as turning. Pushing the joystick forward and backward should make the robot go forward and backward respectively, and pushing the joystick left and right should make the robot turn left and right respectively.

Hint: when calling x and y values from the operator interface, use leftJoystick.

Example: User has joystick full forward. Robot drives forward. User has joystick full right. Robot spins in place to the right. User has the joystick full forward and full right. Robot goes forward while turning to the right.

How you achieve this is up to you, there are algorithms online you can research or come up with your own solution. The tests just verify some basic cases.

We use Xbox and similar controllers for driving the robot:

Next Steps

Continue with the next curriculum challenge: Moving to a target position

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