Students will use the NXT/RCX datalogging feature to identify a hidden
letter of the alphabet using light sensor data.
To program an NXT/RCX vehicle to collect data.
To analyze data and come up with a solution.
MINDSTORMS 2.0 with datalogging
capabilities orROBOLAB investigator.
Large print out of a letter of the alphabet.
Should cover a 8 1/2 by 11 sized paper.
Preparation and Set Up:
Set up the hidden letter on the floor or on a table, but make sure that it cannot be seen.
Have pre-built NXT/RCX vehicles or allow students to construct their own.
Set up computer with MINDSTORMS 2.0 or ROBOLAB Investigator.
Datalogging is used to collect data from the sensors on the NXT vehicle.
This data an then be uploaded on to a computer an analyzed.
The light sensor will be used in this activity to collect information
about the color changes of the hidden letter.
Attach a light sensor to your NXT/RCX car so that it is pointed at the floor. Wire this to port 1.
Open the datalogging feature in MINDSTORMS 2.0, or open Investigator 2 in ROBOLAB.
Program your vehicle to collect light data as it drives (see picture attached). You may need to adjust the power level depending on how fast your car drives over the hidden letter.
Have the car drive across the letter at least 5 times in different places.
This can be done by having your car drive across the letter one way three times, each time moving the car down a few inches, then doing the same thing but in a different orientation.
Upload your data by clicking on the upload button of MINDSTORMS datalogging or in ROBOLAB investigator.
Examine the data for peaks and valleys indicating light or dark areas. From these graphs have students try to decipher what letter the car drove over.
Allow student to continue testing and then to guess what the hidden letter is.
You may want to have a few hidden letters so that students can try this activity several times.
Limit the number of times you allow a car to drive over a letter.
Set up computers running MINDSTORMS.
Gather necessary materials.
Arrange students in groups of 2.
Distribute necessary materials.
Have students build fan-like structure:
Attach two plates in a ‘plus-sign’ design. Be sure the holes line up where they cross! Then take a bushing and attach it to the plates as shown. Make sure the smooth edge faces up and the notched edge is touching the plate.
Slide an axle through the plates and bushing. It is a good idea to secure the plates with a second bushing. Then slide the other end of the axle through a rotation sensor. Use bushings to secure the sensor also.
Use thick paper, index cards, or cups to create sails. Tape or clip these to the plates. Attach the rotation sensor to the RCX. Make sure to plug the sensor into port 1.
Have students write a program in investigator in ROBOLAB:
Write a program in level 1 to record rotation sensor data for a certain length of time.
Adjust sampling rate to a very small interval (decimal).
Download and run the program to measure the speed of the fan blades as you blow on them or from outside in the wind.
Have students upload and analyze the data:
Upload the data to investigator.
You will want to convert data from sixteenths of a rotation into full rotations. Use the compute tool to divide the data in the red bin by 16.
Look and the chart and note trends. What happens when the wind blows harder? softer? How fast did the wind blow? How slow?
Experiment with different types of arms to see what works best (different material for blades/longer blades/wider blades/narrower blades/angled blades/flat blades).
Once you’ve selected a type, try different sizes.