The ‘ball angle’ block (Sensors) is used to get a measurement of angle, between -180 and +180. If the ball is on the left of the robot, the number is negative. If the ball is on the right, the ball is positive.
¶ Rotate to face the ball
Let’s write a program that will rotate the robot to face the ball.
- We need an ‘if’ block (Control) - because the robot needs to make a decision.
- We also need a ‘comparison’ block (Operators) - because we need to check that the ball distance is greater than 100.
We have three conditions:
- If the ball is to the left (ball angle < -20), then the robot should rotate left.
- Otherwise, if the ball is to the right (ball angle > 20), then the robot should rotate right.
- Otherwise, the robot should stop.
We’re using -20 and 20 degrees because the robot can’t stop instantly.
Let’s start with the if. Here, we drag the if and comparison blocks, and we can also press the + to get the ‘else if’ section.
Now we just need to add the motor movement.
- Rotate left means the left wheel needs to go backwards (negative) and the right wheel goes forwards (positive).
- The opposite for rotating right.
