EV3 NXT Compatibility

I ran some tests using the EV3 software to program an EV3 robot with EV3 sensors, an EV3 robot with NXT sensors and an NXT robot with NXT sensors.

This first video shows the set up of the program for all three conditions.

Here’s the first program I ran.  It works as it uses EV3 in all circumstances (hw, sw, and sensors).  I just used it as a baseline.  The robot should drive forward until it senses a close object, stop, wait 2 seconds, back up until it senses a black line (using EV3 color sensor in ref. light mode), stop, wait 2 seconds, back up until it senses the red line (EV3 color sensor in color mode), stop, wait 2 seconds, turn to the right until the gyro sensor senses an increase greater than 90 deg., stop, wait 2 seconds, then drive forward until it hears a loud sound, stop and play fanfare.

Here’s a screenshot of the program (e-mail me if you want a copy of the programs):


I next tried the same program with NXT sensors on the EV3 and a few changes.  I have no NXT color sensor, only a light sensor, so it just stopped at the black line but not the red, and I substituted the touch sensor for the gyro sensor (no LEGO NXT gyro sensor).  It worked fine this way.


Finally I tried the same with an NXT robot and sensors.  Here I ran into a little bit of trouble.  The light sensor in reflected light mode stopped the robot early (before the black line) almost every time.


And that’s that so far.  Some things I would like to try are: working on turns – apparently the NXT does not turn “properly” when programmed with EV3 software, trying the Hi-Technic gyro sensor on an NXT using EV3 software (longshot, huh?) and seeing if I can get EV3 sensors to work on an NXT using either NXT or EV3 software.  Please add any thoughts you have in the comments section.  Thanks!




Gyro Sensor Tests

Image taken from www.legoeducation.us

Gyro Boy – Image taken from http://www.legoeducation.us

I spent some time today playing with the Gyro Sensor.  There seemed to be a lot of issues with it last weekend as I was training a group of teachers.  Though I don’t doubt any of the problems they had (I was there!  I saw it!), I got perfect results every time I tried to use it.

DRIFT – Gyro sensors suffer from drift.  Perhaps a more saaavy engineer could describe it properly, but for me drift means the gyro sensor will start registering numbers even when it is not moving at all.  The way to account for this is to constantly unplug and replug the gyro sensor in when using it.  I did that each time I used it in the following experiments, always using Port View to make sure it read like this:


1. The first program I tried was from Robot Educator.  It has you use the Gyro sensor in the Change Angle configuration.  Robot turns to the right, and stops after an increase of 45, the drives straight.  Here’s what the program looks like:


And here’s the video:

2. Next I tried the same program but with an increase of 90 (right angle).


3. After the change in angle worked, I tried using the gyro sensor in the compare angle configuration.  This first time I again turned to the right until the sensor sensed an angle greater than 45.


4. Similar to last time I kept everything the same but changed the compare to > 90.


5. Now I tried left turns because this is what caused so many problems at the training.  First up is left turn change in angle decrease of 45.  Decrease because the numbers get negative as you turn to the left.


6. Same, but with decrease of 90.  Forgot to get a screen shot of this one.

7.  Wanted to use the compare angle configuration, but made a mistake.  I programmed turn left, stop when gyro sensor sense and angle greater than -45.  Can you guess what happened?


Yep, zero is greater than -45 so the robot stopped turning immediately (faster than you can see) and went straight.

8. Corrected previous example, changed to less than -45.


9. And finally I went with compare angle, less than -90.


Fortunately the gyro sensor worked fine in my tests.  Unfortunately I couldn’t repeat the mistakes that my students made during training last weekend. 



EV3 – Early Reflections – The Good, The Bad, and The Ugly


These pictures are from theEV3  training I did in Yakima last weekend (8/10-8/11) and don’t reflect the words in the post title!  🙂

The Good – People migrating from NXT saw a lot of good in the new robot:

Pieces – the middle hole of the sensors is an axle hole, the square pieces allowing for easy motor connectivity, the medium motor, the colored pieces

Brick – 4 ports for motors, auto id, no assigned port for sensors (e.g. NXT ultrasonic on port 4)

Software – projects and programs took a bit to get used to but were well liked, zoom ability, no data wire problems yet, loop interrupt, multiple switch conditions, the flow of work and not modifying every icon in the bottom left of the screen, the context help and help screens

These were all things that NXT users were head over heels about.  New users of EV3 were excited by the overall coolness, they marveled at The Wave and a basic line follower, but as with a lot of new technology you don’t know what an improvement something is unless you have used a previous version.

The Robot Educator, the Core Set and Expansion Set design files had everybody excited.

The Bad – I wouldn’t say anything was bad.  Mediocre might be a better term.  People were not enthralled with Content Editor, either as a display tool, a way to create assignments and instructions for students, or a way for students to document their work.  Perhaps this was my fault for not presenting it well.  I don’t know – I love it and think it’s the #1 reason to get EV3.  On the other hand one teacher said they won’t use it.

Personally, I am questioning the wisdom of the teacher and student sections of content editor.  The more I look at it, the less I feel like I want to create content that only teachers and not students can see.

The Ugly – Two things fit this category perfectly.

1. The gyro sensor.  It suffers from drift.  This means that you have to unplug it often or it will start to change numbers.  You can see this happen using port view; a perfectly stable gyro sensor will just start counting 1,2,3…  It gets quite frustrating.  We had a lot of problems getting it to work for left turns using negative numbers, but as you will see in my next post, this is not always the case.  Either way, people were quite frustrated with it.

2. The EV3 screen.  I had too small an example to say for sure (and I hope this doesn’t come off ageist) but the older students in my class had an incredibly difficult time reading the screen.  Some of the younger men and women too, but it seemed like those with poor eyesight really struggled.  This is a shame.  I have heard back-lighting would cost too much to add, perhaps someone will hack an simple/cheap solution.

I’m not sure where to include On-Brick programming.  Those migrating from NXT liked its flexibility but felt like it was not intuitive.  However the youngest teachers claimed it was a snap and that middle school students would pick it up right away.  So again an age thing, which I’m not comfortable making blanket statements about but it did seem to show differences within the small number of students I had.  Coupled with the hard to read screen though, some people really hated the on-brick programming.

So that’s my initial observations after training a group of people on EV3 for a weekend.

Taking a break from Robots, it’s Awesome Sauce!

Quick explanation – my team at the LEAP (LEGO Education Advisory Panel) conference  this year was called Awesome Sauce.  I grew cayenne peppers this year.  I made hot sauce, I called it Awesome Sauce. Turns out it’s really easy to do.  Here’s the recipe as I did it.  Keep in mind I’m no cook and have no training at this, just did a quick google search and made it up as I went.

1.  Gather your ingredients.  Onions and cayenne peppers from my garden and garlic from the supermarket in this case.  Some people like to add carrots for balance but I just wanted it spicy hot!

IMG_22162. Chop the tips and stems off the peppers.

Wait!!!  Are you wearing gloves?  If not then wash your hands several times during this process and do not touch eyes, children, inside nose or mouth, or genitalia.  Seriously.

IMG_22173. Measure.  I’m not sure why, I think I just wanted to see how much I have and get an approximation of how much vinegar to add.

IMG_22184. Chop and dice other stuff.

IMG_22195. Roast/toast it by heating on low in a frying pan with no oil.  This worked well to add a nice flavor layer to cayennes and garlic, but did nothing for the onions except make them stick to the pan.  No pic for this step, sorry.

6. Put it all in a blender.

IMG_22207. Add vinegar.  How much?  I don’t know.  You want enough to make it saucy (as in smooth and pourable) but not so much that the vinegar flavor overwhelms the pepper hotness.  Add a little at a time while you’re blending and try with a spoon, not your finger tip!  Add some more.  Stop when you get it right.

IMG_22218. Blend baby, blend!

IMG_22229. Put in saucepan, bring to a boil.  Let it simmer for a while – like long enough to make the kids lunch and have a beer. 🙂

IMG_222310.  If your house smells like vinegar, you put too much in.  If your eyes are stinging it’s vinegar, if they’re burning it’s pepper.  You want a nice burn/sting balance.  🙂 Once you’ve simmered for a while, strain the mixture.

IMG_222411. And finally bottle the stuff.  I still have to make a custom label for my awesome sauce.

Enjoy!  Let me know how yours went when you make it!IMG_2225IMG_2226

EV3 Training Day 2


Working on the Stop at Line Tutorial from Robot Educator

Day 2 of our training in Yakima saw the teachers really get into EV3 and start going beyond the tutorials to work on some of the challenges I posted: obstacle course, line follower, counting lines, etc.

While there were a ton of really great successes, one of the things the group found difficult was the use of the gyro sensor.  More on that in a later post.  In the pics below you can see a group struggling to get it to work properly.

It says to do this...

It says to do this…

Hmmmm..... Grrrrrrrrr.....


The next group was trying to get their robot to stop on the yellow line.  As you can see in the three youtube videos they first forgot to add a motor off command, they they looked for something less reflective rather than more reflective (they stop in empty space), and finally they get it right.

That little fist pump at the end is all you want to see as an instructor whether your students are teachers or middle schoolers.  I could care less about grades.  🙂

This group finally got their robot to turn with the gyro sensor, but it was far from easy, as I said, look for a later post on this.

These two groups did some classic line following:

Listen to the interesting background chatter here:

Finally, Eric borrowed an expansion and core kit for the night and stayed up until 1 am Sun. morning working on the elephant.  He finished it just about 4 pm Sunday.

EV3 Training in Yakima – August 10 and 11th

Time to put myself to the test.  Just completed the first day of a two day EV3 training with about 25 teachers in Yakima.  Great facilities and resources provided by Moe Broom, Eric Franz and the staff at Yakima CTE.  And a wonderful set of teachers had a lot of fun and learned quite a bit too!

I split the class in two and had half of them build Damien’s Riley Rover, while the other half built LEGO’s Robot Educator Model.




BuildingRileyRover2BuildingLEGOREM2BuildingLEGOREM3 BuildingLEGOREM4

After they were done building they went through the Robot Educator Tutorial for Tank Steering and here’s the results:

After that we went on to the Wave of course.  Here’s an early attempt and the almost perfect final: