Introduction:
In this page we will walk through the steps to use the Data Logging function of the LEGO® MINDSTORM® robots. We have both the NXT and EV3 version, this page is for the EV3. If you are using the NXT click here.
Preparation Needed for the Activity:
LEGO® Robot
Cable for connection to the computer (use this instead of bluetooth connection to avoid cross robot errors)
Computer with the LEGO® software installed
NXT build files (need two extra 24 tooth gears): LEGO Digital Designer file, or PDF build file
Programs for NXT: Gait ; Walk40 ; Walk60; Walk80 ; EditVelocity
Handouts: Downloading Programs ; Clearing Memory ; Uploading Data
Part 1 - EV3 Data Logging Set-up: Time 15 min
The data logging feature is an easy way for students to see what information that robot was able to collect during its navigations. The programs that they have been running all along have collected data, regardless of the knowledge or accuracy. For this section we will walk you through what has to be done to clear the memory for the data logging to store as it could be full at this point. We will then provide the instructions to upload the data after the activity.
Clearing the Memory could remove all the programs from the robot. This should be done prior to the day that you plan to run the Data Log activity as you will have to reload the program Walk40EV3, Walk60EV3, and Walk80EV3 for the activity on each robot.
Downloading a Program to the EV3 Brick
Open each program and connect a powered up robot
With one of the programs active you will click on the Download button located in the bottom right (it looks like a down arrow).
Repeat this for each of the programs.
You are now ready to run the program on the robot.
Running a Program on the EV3
With the robot on, press the right button once (moving to the files screen)
Press the down button until you highlight the program you want to run, then press the center button
You should now see this screen with the word program under the selected program. Press the down button to highlight program.
When you have the robot in place and are ready for the robot to start, press the center button
Clearing the Memory on the EV3
If you rather have a handout for the students to complete this, it is attached at the bottom of the page.
With the computer turned on, Connect the EV3 to the computer using a usb cord
Turn on the EV3
Open the EV3 program on your computer
When the software opens you should see this screen
Go to File and select Open Project
When the list of programs appears select one of the EV3 programs (i.e Walk40EV3)
When the file opens
You will see this screen and you will click on the Brick Information button, as shown by arrow number 1 here
Then click the Open Memory Browser button shown as arrow 2
This is the screen that should appear
You will now have two ways to delete files
You can delete all the files in each of the program folders
Select a folder and then press delete
You can delete only the data files, you would not have to reload the programs if you do this.
Double click the folder to show the list of files.
Select each of the MyData files and click delete
Click the closed button
Now with the Memory cleared you may need to reprogram the robot if you deleted all the files during the process above. If you did, then you will download the programs again using the walk40EV3, walk60EV3, walk80EV3 programs.
Uploading the data log results
With the computer turned on, Connect the EV3 to the computer using a usb cord
Turn on the EV3
Open the EV3 program on your computer
When the software opens you should see this screen
Step 1 - Select New Experiment
Step 2 - Select New Experiment
Step 3 - Click Open
When it opens, You should have a blank analysis screen as seen here.
It should indicate that your EV3 is connected
You should see the upload button now in the lower right corner
Click the upload button indicated by the arrow here
You should now have the Data Log File Manager box open
Navigate to the log files that were just collected during the activity
They will have to import each one separately and they will all appear on the one screen so Warn them to only select the two they need first
This should be My Data and My Data_1
The other files would be additional runs they completed
When they first upload the data the scales will be set with the max range. This prevents them from seeing the intersections.
Rescale the data by adjusting the scale on each scale bar on the left
When they move the mouse over the scale at the midpoint they will see an image appear as indicated by the arrow here.
When it appears they should click to adjust the scale based on the data range
To be able to see the exact data they should use the point analysis tool
Click the microscope button and select point analysis
When the tool opens they will be able to click on the line and drag it to each point where the robot crossed a black line (brown line minimum)
The chart will then provide the exact rotation data for the motors at that point
If the motor data is not in rotations it can be changed in the sensor setup box by selecting rotations for the motors
They should now repeat this for all of the experiments they need to collect data for to complete the activity