Rotation Sensors My Version

1. Rotational Sensors Robotics Academy 2002. All Rights Reserved. The rotation sensor can measure the rotation of the wheels. By measuring the rotation of the wheels, and knowing the diameter of the wheels, we can measure and control how far the robot travels. Remember: The rotation sensor has 16 counts per rotation.

2. Geometry Review Robotics Academy 2002. All Rights Reserved. The Diameter is the distance across the circle through its center. It is twice the radius. The Circumference is the distance all the way around the circle.

3. Geometry Review Robotics Academy 2002. All Rights Reserved. 1 turn of the wheel is called 1 revolution How big is 1 revolution? It is as long as the circumference of the wheel!

4. How do I calculate the circumference (1 revolution)??? C ircumference =  x Diameter   = 3.14 

5. How do I calculate the circumference (1 revolution)??? C ircumference = 3.14 x R evolution = 3.14 x What about 1 revolution? How do I calculate that?

6. Let’s Practice! C ircumference = 3.14 x The diameter of my wheel is 2 cm C = 3.14 x 2 6.28 cm

7. Let’s Practice! C ircumference = 3.14 x The diameter of my wheel is 3.5 cm C = 3.14 x 3.5 10.99 cm

8. Circumference Robotics Academy 2002. All Rights Reserved. Question: When this robot’s wheels make one revolution, how far does the robot travel? Answer: One circumference of the wheel!

9. Count or Click Robotics Academy 2002. The rotation sensor has 16 counts per rotation. 1 count or click 2nd count or click

10. How big is 1 click? Robotics Academy 2002. Circumference 16

11. Let’s Practice! 1 Click = C : 16 The diameter of my wheel is 3 cm C = 3.14 x 3 0.58… cm 0.6 cm Click = 9.42 : 16 9.42

12. Let’s Practice! 1 Click = C : 16 The diameter of my wheel is 2.5 cm C = 3.14 x 2.5 0.4906… cm 0.5 cm Click = 7.85 : 16 7.85

13. Let’s Solve Some Problems! The diameter of my wheel is 4 cm, the length of the table is 50 cm C = 3.14 x 4 63.7.. clicks Click = 12.56 : 16 12.56 cm Determine how many clicks it will take to drive your robot on the side of your table. 0.785 cm 50 cm : 0.785 cm

14. Let’s Solve Some Problems! The diameter of my wheel is 3 cm, the length of the table is 104 cm C = 3.14 x 3 176.3... clicks Click = 9.42 : 16 9.42 cm Determine how many clicks it will take to drive your robot on the side of your table. 0.59 cm 104 cm : 0.59 cm

15. Let’s Solve Some Problems! The diameter of my wheel is 1.5 cm, the length of the table is 104 cm C = 3.14 x 1.5 358.6 clicks Click = 4.71 : 16 4.71 cm Determine how many clicks it will take to drive your robot on the side of your table. 0.29 cm 104 cm : 0.29 cm

16. Extra Info

17. Example Robotics Academy 2002. All Rights Reserved. The diameter of this wheel is 8 cm. C =  x D. That means its circumference is 8 x 3.14 = 25.1 cm. The rotation sensor has 16 counts per rotation. That means the robot will travel 25.1 / 16 = 1.57 cm per sensor count.