C - Secure the Planet!

Make sure your robot is setup in the same way as the previous sections!

For the rest of this lesson, we need to be able to make the robot turn accurately.

Build the simple test program in the picture - it should make your robot spin on the spot for 1 second, and then stop.

There are 1000 milliseconds in 1 second - adjust the number until your robot turns by exactly 90 degrees. Don't forget to get the challenge checked off when you've done it!

Now you can turn by 90 degrees, write a program that makes your robot move in a square!

It should like something like the example in the picture but your 'delay' times will be different.

If you think about it, you only need to reverse 1 motor and then set it to forwards again to change direction - one motor can be going forward all the time.

Also, you don't necessarily need to stop after turning - just change the motor going in reverse to go forward again!

Making that last program took a while - and the robot was just doing the same things over and over again.

Say we wanted to drive in a square 10 times - that would take ages to program!

Driving in a square was doing the same thing 4 times:

Drive Forward

Delay

Turn

Delay

We can use the loop to get the computer to repeat these steps for us!

So far, we have just been using the setup part of the program.

Any code inside the setup gets run only once, as soon as the run button on the robot is pressed.

Once the setup has finished, any code in the loop is run again and again until the robot is turned off!

Change your program so that you only have some lines of code in the loop, that make the robot:

Drive forwards

Turn 90 degrees

Don't forget, you still need the invent.begin(); line in the setup!

Check the picture for a hint if you need it - the program in the picture will drive forwards, then turn 90 degrees, but it will only do it once!

Now your robot can drive in a square using a loop, let's change the code so it will drive in a figure of 8.

Have a look at the picture if you don't know what a figure of 8 is.

Try to split the shape up into 2 sections, and put it in the loop''' to reduce the length of your program.

Make sure your robot drives in the figure of 8 properly, and ends up where it started !