Category Archives: EV3

Robot Perspective


Seeing the camera comments in the robot game and update got me thinking how cool it would be to have a camera on the robot.  G, my son, rigged up a jig that held my iPhone in place on C’s red run attachment.  Above is the result.  Really cool!  How sad, my son told my daughter “Really Cool” is what old people say.  He also said I was old!

G adding a third motor to the base robot

Code Crackers Base EV3 Robot

Like the Capital Girls, the Code Crackers built the base EV3 robot. They also elected to go with the big wheels for speed.  Being 8th graders, when they are focused they can get a lot done. For our robot build meeting, they split between builders and programmers.  The programmers built a music master program and base escape.

Below is the program the Code Crackers wrote for the music challenge.  They used notes, not sounds like the Capital Girls.  I am always amazed at the different solutions the two teams come up with when given the same challenge.  Sometimes they are very similar, other times they are polar opposites.

Master Music Program

Master Music Program

The Code Cracker’s Base Escape program has recovery logic incorporated. To start, I challenged them to stop at the line.  Once they had that master, the challenge was to stop at the line if the light sensor stop working (unplugged in this case).  At states in 2011, they had some big issues with light sensor and learned this recovery concept.  In 2012, the mentored the Capital Girls Too, who then used it for the Senior Solutions medicine mission.  Ironically, the mentoring team, 7th graders, learned from the 5th team.  Who was mentoring who?  The workshop challenges and programming posters have really advanced the teams’ programming capability.  They have learned that you can do some cool stuff with a loop, switch and logic block.  This is case where the solutions are the same, the only difference may be some block orders.

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Capital Girls Building a Base EV3 Robot

Both my teams are very familiar with the NXT, and we had to to figure out how to get them familiar with the new EV3 platform in way that did not take up too many meetings.  Lego made this easy by including an instruction book for building a great base robot.  Our goal was to build a base robot to get familiar with the new set and begin learning the programming interface.

cgbasebuild

 The Capital Girls Team built the base robot in about 30 minutes, including using the wheels they elected to use when doing robot planning.  With 6 of the 10 team members at this meeting, we split into build and program teams.

The base robot the girls built was basic, with two motors for differential turning and a color sensor.  C, my daughter, later spent some adding a third motor.

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Color Widget

While the build group was building, the program team wrote a program they called Master DJ.  It plays a different animal sound based on the color detected by the color sensor.  The goal here was to teach advanced program flow by doing something fun.  We discussed how this program might be used for the challenge.  The girls came up with using it to detect objects and to determine which program to run.  By doing the challenge, they reinforced their understanding of the loop and switch blocks.  To figure out the logic, the girls referred to our Program Logic Poster.

Here is the first version the Master DJ program; it has evolved to exit on the color sensor detecting white – and makes me want to invest in earplugs.

MasterDJ

 

 

 

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EV3 vs NXT: Which one to use?

Disclaimer: I am a geek.  I love new technology and always want the latest and greatest,  That being said, if you are trying to decide between sticking with the NXT or diving in with the EV3, I would recommend the EV3.  The NXT is great and using it in competition will not be a disadvantage.

This year, the plan was for the Capital Girls to use the EV3 that was provided by our PTA, with the understanding I will train coaches next year.   The Code Crackers were going to use their NXT, since it’s their last year of FLL.  After playing with the EV3, I wanted one for the Code Crackers to use.   Like I said, I am a proud geek.  Here is my rationale:

Software Learning Curve

The software interface is very similar, reducing the learning curve.   The concept is the same – drag blocks from a palette onto the canvas and set the properties. The big advantage about the EV3 Software is the properties are inline with the block.  I also like how connectors work and the fact you see the what is in what port.  Keep in mind, you can use the EV3 software with a NXT brick.
LineDetection_ev3

 4 Motors

The NXT has three motor ports and comes with three motors.  If you use two motors for the wheels, you have to use gears to distribute power.  The EV3 comes with four motor ports, and teams are allowed to use four motors in the Nature’s Fury Challenge.  The EV3 only comes with 3 motors, but you can use NXT motors or order a fourth.  I thought that they would limit everyone to three motors this year, as the ability to use a fourth is an advantage.  That said, be sure to read the challenge rules for yourself; don’t take my word for it.

Chassis and Motor Attachment Interface

MotorInterface The new chassis and motor attachment interface are very strong, which should make a for more consistent robot.  A robot that will go straight.

 

 

Program Debugging

When connected to the robot via blue tooth, you visually see the program run.  This will be great for guiding and debugging.

ProgramFlow

 

 

 

 

 

 

EV3HardwareDifference

EV3 vs. NXT: Hardware

I love what Lego did with the EV3.   The new brick power and functionality is fantastic, but I think the addition of the new elements and attachment interfaces will make for stronger, more consistent robots.  Yes, I used the words ‘consistent’ and ‘robot’ in the same sentence.

New Chassis Pieces

MotorInterface

Lego added two chassis pieces to the the set.  This may not seem like a big deal until you join them with the new motor.  The connection is very strong, which should create a robot that goes straighter and is more consistent.  I know, I used a bad robot word.

 

znapNew Treads

Lego did add a new tread system to the EV3. Treads look cool and every boy wants to use them, but in my experience, only use treads for FLL if you don’t want a robot to go straight.   They are great for climbing but the consistency trade off is not worth the gain.  Neither of my teams nor I have tried out the new treads yet.  The new system may work better, but I still have nightmares about treads.

 

Wheels

Not in EV3 Kit

Motorcycle Wheel

wheelI want the old wheels back.  I am not a fan of the new fat tires.  I have not tested or seen my teams test them but the bounce screams inconsistency.  I am sure there is a reason for this fat tire design, I just don’t see it.  Also, the bigger the wheels the faster the robot.  There are no big wheels.  To satisfy my team’s big wheel addiction, we added the Lego Motorcycle wheels to our kits.

 

EV3 Interface

EV3 vs NXT: Software

The EV3 software is very much like the NXT.  My Code Crackers team wrote a line detection program with recovery logic on the EV3 in under 10 minutes.  This was their first time using the program.  The location of the tools pallet is different – on the NXT it is on the left and in the EV3 it is at the bottom.  Same concept, though, drag blocks to the canvas and set properties.

Inline Properties

My favorite change is inline properties, at least that is what I call it.  Properties are visible and editable on the block – no more clicking a block to modify properties in the properties window.  This makes coding faster and the code more readable.  Below are examples of the line detection program in both the NXT and EV3 software.  The program looks for a black line.  If the black line is not detected after .94 rotations, it exits the loop.  The program uses a reset motor block, loop with logic exit condition, rotation sensor, light sensor and logic block with an “Or” condition.

linedetection_nxt

NXT Line Detection with Recovery Logic SampleLineDetection_ev3EV3 Line Detection with Recovery Logic Sample

Data Wires

ev3software_connectors

The data wire interface is much simpler and cleaner.  The shapes, half circles and triangles, indicate what can be connected.  This is a big improvement.

datawires

Source: EV3 Help Content

Port View

EV3PortViewerWhat port is the color sensor?   In the EV3 Mindstorm software, you have access to a port viewer to see what is connected to each port.  I love this feature, no more guessing or cable tracing.

Flow Indicator

This is really cool – when connected to the brick, you visually see the program flow.   This makes debugging so much easier and fun.

ProgramFlow

EV3 Software on NXT

We also tested the EV3 software with an NXT brick.  It works.  Even if your team is not using the EV3, you may want to utilize the new software just for the inline properties.

 

Organizing 541 (Core Set) + 853 (Expansion Set) Legos

Plano 1374 4-By Rack System 3750 Size Tackle Box

Plano 1374 4-By Rack System 3750 Size Tackle Box

How exciting! The EV3 Core and Expansion Sets you have been waiting on for months just arrived.  Now that the stress of wondering if it will arrive in time for the Nature’s Fury challenge has been lifted, you have to start organizing and learning it.  There are several options for getting your kits organized:  you can use the Lego bins that shipped with the set, throw it all in box, hire a professional organizer or exploit a tackle box.

I love the Lego bins that ship with the kit, I use them all the time to sort stuff, but I find they are not the best solution for our kits.  The pieces get mixed up easy, and theirs doesn’t lend itself to the level of organization I prefer.  My solution?  A tackle box.  To be specific, I used a Plano 1374 4-By Rack System 3750 Size Tackle Box with the addition of a 3750 Stowaway box that fits in the top section, along with the wheels and cables.

Plano1374OpenI like the tackle box over other options because it is very portable and durable and, most importantly, it keeps pieces organized.  I would also recommend looking at solutions from Robotics Learning.  I  used their kit for the NXT, and it worked great.  Their labeling is great, and I’m eager to see what they offer for the EV3.