Programming Drive Forward and Reverse - C++

This exploration will introduce students to basic drive forward, reverse, and waiting programming behaviors. These basic skills will help them to succeed in the next activity and in the Strike Challenge at the end of this STEM Lab, when they will compete in bowling by using the Speedbot.

Using the V5 Speedbot (Drivetrain 2-motor, No Gyro) template project enables the students to program the Speedbot to move forward by just using one instruction.

Here is an overview of the User Interface of VEXcode V5. Students will be introduced to these tabs/buttons during the activities in this Momentum Alley STEM Lab. Links are also provided throughout the STEM Lab to provide more information about these tabs/buttons.

If this is the student’s first time using VEXcode V5, they can reference the Tutorials at any time during this exploration.

Model each of the troubleshooting steps for the students.

• Project Names can have spaces between or after the words.

  

• You can ask students to add their initials or the name of their group to the project name. This will help differentiate the projects if you ask the students to submit them.
• Because this is the first activity with programming your students may attempt, you should model the steps, and then ask students to complete the same actions. The teacher should then monitor the students to ensure that they are following the steps correctly.
• Make sure that the students have selected Open Examples from the File menu.
• Make sure that the students have selected the Speedbot (Drivetrain 2-motor, No Gyro) template project.
• You can point out to the students that there are several selections to pick from on the Examples page. As they build and use other robots, they will have a chance to use different templates.

• Point out that when they first opened VEXcode V5, the window was labeled VEXcode Project. VEXcode Project is the default project name when VEXcode V5 is first opened. Once the project was renamed Drive and saved, the display was updated to show the new project name. Using this window in the toolbar, it is easy to check that the students are using the correct project.

• Tell the students that they are now ready to begin their first project. Explain to the students that by just following a few simple steps, they will be able to create and run a project that will move the Speedbot forward.

• Remind students to save their projects as they work. The C++ sections from the VEX Library explains saving practices in VEXcode V5.

This is a good point to pause and have the students review the steps that were just completed on starting a new project in VEXcode V5 individually or in groups. Ask the students to reflect individually before sharing within their group or to the whole class.

You may notice an autocomplete function as you start to type the instruction. Use your “Up” and “Down” keys to select the name you want, then press “Tab” or (Enter/Return) on your keyboard to make the selection. For more information on this feature check out the C++ article.

• Remind the students to disconnect the USB cable from the Robot Brain. Having the robot connected to a computer while running a project could cause the robot to pull on the connection cable.

Ask the students to predict what they think will happen when this project is downloaded and run on the Speedbot. Tell the students to record their predictions in their engineering notebooks. If time allows, ask each group to share their prediction

• Model running the project in front of the class before having all the students try at once. Gather the students in one area and leave enough room for the Speedbot to move if it is placed on the floor.

• Tell the students it is now their turn to run their project. Make sure that they have a clear path and that no Speedbots will run into each other.

• To change the driveFor command from forward to reverse, simply change the first parameter to -100. This will have the motors in the drivetrain move in the opposite direction.

• The number of mm can be changed, but for this example we will leave them at 100 mm as set in the previous step.

• Remind them to disconnect the USB cable from the Robot Brain before running the project.

• Remind students to save their projects as they work. The VEX Library has sections for C++ that explains saving practices in VEXcode V5.

• Using a wait command will not end the project, it only pauses the robotic movement.

• If the students are using a computer, remind them to disconnect the USB cable from Robot Brain before running the project.

• Remind students to save their projects as they work. The VEX Library has sections for C++ that explains saving practices in VEXcode V5.

Ask the students to share their solutions in pairs before discussing them as a whole class. Facilitate the discussion by asking:

• Did you face any difficulties while programming this challenge?

• Did your robot behave like you expected based on your project? Why or why not?

• If you could do the challenge over, is there anything that you would have done differently?

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();
  // Begin project code

  // Drive forward 10cm
  Drivetrain.driveFor(forward, 100, mm);
  // Wait 1 second
  wait(1, seconds);
  // Drive back to the starting line
  Drivetrain.driveFor(reverse, 100, mm);

  // Drive forward 20cm
  Drivetrain.driveFor(forward, 200, mm);
  // Wait 1 second
  wait(1, seconds);
  // Drive back to the starting line
  Drivetrain.driveFor(reverse, 200, mm);

  // Drive forward 40cm
  Drivetrain.driveFor(forward, 400, mm);
  // Wait 1 second
  wait(1, seconds);
  // Drive back to the starting line
  Drivetrain.driveFor(reverse, 400, mm);

}