Mission 2: Controlled Movements - Precise Turns

Knowing how to control the movements of your robot will help you greatly in programming.  Guessing and checking can work, but doing so can take a lot of time.  Let's learn how we can track the movements of our robot, and how we can use math to solve our robotics challenges quickly!

On Table 2, the inner circle outlines 4 points.  If you start at 0 degrees and turn 90 degrees to the right, you will have turned one-quarter of a circle.  180 degrees is a half of a turn, 270 degrees is three-quarters of a turn, and 360 degrees gets you back to 0, which means that you have turned around in one complete circle.

These robots turn by having one wheel rotate faster than the other wheel.  This means that one wheel must travel a longer distance to get to the same finish point as the other.  We call this wheel the outside wheel.  The wheel that travels less distance is the inside wheel.  The outside wheel is always the opposite wheel of the direction you are turning.

Check out the pictures below, depicting a robot during various stages of a left and right turn.  What do you notice about the differences between the two?  How are the inside wheels and outside wheels different?

The "Steering" option in your move command allows you to adjust how sharply your robot turns.  This means that you are really controlling how much faster the outside wheel travels than the inside wheel.  Move the slider only a little, and your robot will make a very wide turn. The outside wheel travels only a little faster than the inside wheel.

Move the slider more, and the difference in speed is greater, meaning a sharper turn.  Check out the videos below and compare them to how sharp a turn was set in programming.  Each turn is set for a duration of 3 rotations.

On Table 2, there is a circle with degree marks from 0 to 360.  Your job is to make your robot turn in place, and see how many rotations are needed to turn exactly 90, 180, 270, and 360.  Use the Learning Mission 2 Worksheet to guide you through the activity.