15. More About Light Sensors

Living on the Edge! Go Full Screen to see in greater detail?

Examine the Movie

The program is similar to the last.

Here the RCX Cart runs over the table at slow speed (use a modifier to reduce the speed).

It stops when it gets to the edge of the table.

While the movie gives clues as to how the program is created, it also shows that the Cart should stop at the table's edge, no matter how long it has been traveling for.

The pictures below provide hints as to the icons and possibly the settings you might use to create the program in the movie. The numbers might be very different from one you might use. They depend on how much light there is in the room.

Light Sensor at start - remember lighter surfaces reflect more light and will give higher readings.	Light Sensor at end - darker surfaces reflect less light and therefore will give lower readings.

What you have to do!

1. Start the Robolab Software - if it isn't already open.
2. Make sure you choose Inventor Level 2.
3. Create the program to make the Cart work like the one in the Video, but instead of using the table edge, use a piece of dark paper.
• Think about what might be happening to the light levels as the Cart passes over the different surfaces.
• Think about the different Icons you could use. - Are you waiting until it gets darker or are you waiting until its getting lighter.
4. Transfer your program to the cart.
5. Once the program is working correctly Tick Off Task 15 in the main Robolab Progress Grids.

Continue to the Light & Dark Challenge - Exercise 16: