Monday, August 29, 2016

Mini LEGO Amusement Park!!!!!

That's right folks, a Knights of Bots member has just finished building a mini LEGO Amusement Park named LEGOland Mini! Built at Brics~2~Bots Lab, this project took all summer to create. It consists of three rides, a Ferris Wheel, a Free Fall, and a Carousel. All LEGO rides were inspired by actual amusement park rides. A picture of LEGOland Mini is shown below.

Here is a video of LEGOland Mini:


About the Park

LEGOland Mini was built using EV3 kits. The Amusement Park rides are powered by the same EV3 brick. Pictures of the EV3 brick used to power the rides is shown below.

Here is a screenshot of the program used to run LEGOland Mini:
As shown in the program above, the rides are all activated using one touch sensor.

This is the program for the All_Rides My Block used in the program:

The All_Rides My Nlock consists of three My Blocks. Each My Block is the program for a different ride at LEGOland Mini. The individual my block programs will be shown and explained further in this article.

Motor Drop: The Free Fall

The Free Fall is powered using one EV3 medium motor, and one EV3 large servo motor. As shown in the video of the Amusement Park, the medium motor uses a rack gear to move the large servo motor towards the free fall ride. Then, the servo motor latches on to the handle and winds up the string holding the sitting mini figures on a gondola. After the gondola with mini figures reach the top of the Free Fall, the program pauses. Next, the medium motor quickly pulls the large motor away from the ride, causing it to detach from the handle holding the gondola of mini figures up and, in turn, the gondola with mini figures "free fall" down. 

A challenged was encountered while creating the Free Fall. The gondola fell down too fast during the ride; creating a very unpleasant and unsafe impact for the minifigures :-(. Since LEGOland Mini prioritizes minifigures' safety above all else (that and we don't want a minifigure law suit), we had to find a solution to this problem. One solution was to use the motor to bring the minifigures down, however that would defeat the purpose of the Free Fall.  After all, the "falling part" of the free fall is actually gravity and mass at work. Then, after experimenting, researching, and discussing, a great idea came forth. Actual free fall rides aren't really "free falls". If they were, then the rides would become deadly. Engineers control the speed of the free falls by slowing them down. This stunning realization lead to this idea: we can use gears to slow down the fall and make it safer for minifigures to ride on.

After testing out various gearing configurations, we finally found one that worked. Here's a picture:

The programming for the free fall was relatively simple (there is a picture of it below).
Note: The audio block in the program titled "SCREAM" is the screaming sound you hear when the minifigures fall down. This is a feature added into the program to make the ride more realistic.

Working with Gradual Increase in Speed: The Ferris Wheel

Ferris Wheel (Front View)
Ferris Wheel (Side View)
The Ferris Wheel uses one EV3 motor. Shown in the Amusement Park video, the EV3 motor spins the Ferris Wheel. However, while watching the video you may have noticed something unusual about this ride; the Ferris Wheel's speed increases and decreases. This idea came from a Youtube video made by Builderdude35 titled: How to Program a Motor Acceleration MyBlock in EV3-G. In this video, he explains a program that gradually increases the motor speed. Upon watching this video, the creator of LEGOland Mini was inspired to try this idea out on the Ferris Wheel.

First, the Ferris Wheel starts out at a motor power of 5. Then, the power/speed gradually increases until the motor power reaches 15. Next, the motors stop and reverse, decreasing speed and going in the opposite direction. The wheel's power/speed will then decrease until the power reaches 0, causing the ride to stop.

Here is a screenshot of the program used for the Ferris Wheel (I broke the pictures of the program into two pieces to make the programs easier to read):

The program used for the Ferris Wheel is a bit different from the program used in Builderdude35's video. Instead of gradually increasing motor speed, the Ferris Wheel program increases and decreases motor speed. In addition, the Ferris Wheel program has a Loop for Motor Rotation to establish a target power. The program will loop for x amount of times until this target power is reached. Whereas is Builderdude35's program, his program uses a loop for count; which controls the number of times the program loops. Unlike our program, this program has no set target power.

The Carousel

The Carousel uses one EV3 Medum Motor. The Medium Motor spins a 20-tooth Double Bevel gear, which meshes with a 20-tooth Bevel gear. This causes the Carousel to spin, as shown in the video of the Amusement Park. 

The programming for the Carousel was similar to the program used for the Ferris Wheel. The ride's speed gradually increases and decreases.

Here is a picture of the Carousel's program (I broke the program into two pieces to make it easier to read):

LEGOland Mini News

LEGOland Mini might evolve into a larger Amusement Park in the future... 

Happy building!

Thursday, August 4, 2016

A LEGO Power Functions Creation

One of the Knights Of Bots members recently began to work with LEGO Power Functions (also referred to as LEGO PFs).  After about a week of experimenting, the member came up with a weird LEGO Power Functions contraption (shown below).

The contraption
A picture of it from the bottom
Here is a video of the contraption at work:


The contraption was inspired by a book titled, The LEGO Technic Idea book: Fantastic Contraptions, by Yoshihito Isogawa. This book is filled with pictures of fantastic LEGO contraptions (hence the title). Upon reviewing the book, we were inspired to try out some of his brilliant ideas. 

This creation/contraption is a combination of two of the gearing systems found in Isogawa's book. Both gearing systems are powered by a LEGO PF rechargeable battery. The first gearing system is very simple. It consists of an old LEGO Technic motor (Electric RC Race Buggy Motor 2002) which actually has two axle holes for turning attachments, a bevel gear with twelve teeth, and a double bevel gear with 20 teeth. The gears result in a spinning motion, as shown below. This system can be found in pages 52 and 53 of the book.


The second gearing system, in my opinion, is very interesting. It is powered by a LEGO Power Functions Medium-Motor. There are 3 double bevel gears with 20 teeth and one double bevel gear with 12 teeth.

 As shown in the video below, the motor spins the 12 tooth double bevel gear to mesh with the 20 tooth double bevel gear. As the motor changes directions, the double bevel gears shift in the corresponding direction. If the motor was spinning to the right, the double bevel gears would shift to the right, causing the two gears to mesh with the double bevel gear on the right. If the motor were to shift to the left, the two gears would shift to the left, causing the to gears to mesh with the double bevel gear on the left. This gearing system can be found on pages 148 and 149 of the book. This gearing shift is what makes this contraption unique.


Feel free to make the contraption described in this article. If you would like to purchase the LEGO Power Functions kit, the LEGO Technic motor, or Yoshihito Isogawa's book, the links are at the end of this post. The link for Isogawa's website is down below too.

LEGO Technic motor

Tuesday, July 12, 2016

The Desktop Helper

Have you ever wanted a robot that assists you while you're doing work? Recently, one of the members of Knights of Bots finished working on a robot that does just that. The robot is Desktop Helper. It was made using the LEGO Mindstorms EV3 set.

The Desktop Helper

Desktop Helper can do two things: play music and hold pencils. To play music, simply wave your hand in front of the ultrasonic sensor. Doing so will cause the robot to play the chorus of "Don't Worry be Happy" by Bobby McFerrin.

To use the pencil holder, press the button. After pressing the button the pencil holder will move down so you can collect your writing utensil or place a writing utensil inside the holder. Press the button again for the pencil holder to move back up.

Here is a video of how the Desktop Helper works (remember to turn the volume up so you can hear the music):


To program Desktop Helper we used LEGO Mindstorms EV3 Home Edition software. While programming our member encountered a problem, the EV3 could not store sounds that were longer than approximately 8 seconds. In order to play a song, one would have to use a sound editing software to chop up the song into 8 second intervals and save each piece of the song. Then, the song blocks would have to be put together, in order, in the program. Our member used a song editing software named Audacity (a free program) to break the song into intervals. Our mentor/coach (L3GoBots Lady) helped us break the song into intervals. Then each song piece was saved as a sound block and put into the program. However, the song pieces were placed in a different order to make the song fluid.

A screenshot of the Desktop Helper Program

You may have noticed from reading the program (or watching the video) that while playing the song the robot displays a smiley face. Here is a picture of it:

Sunday, June 5, 2016

NXT vs EV3: Brick Comparison

NXT vs EV3

There have been three generations of LEGO® Mindstorms®robot kits since 1998. The first being the RCX (released in 1998), the second the NXT (released in 2008), and the third the EV3 (released in 2013). LEGO® no longer makes NXT or RCX kits or offers updates for the programming software. To buy a RCX or NXT now, you will have to search for collectors who sell them and they will be quite expensive. So, those of you who still have an RCX or NXT might be wondering should I shelf the electronics of the RCX or NXT and run out and buy an EV3? Well, if you want to continue with Mindstorms robotics you will need to eventually buy an EV3 kit. However, don’t be so quick to toss away the old RCX and NXT kits.

Let’s take a look at the electronics of the NXT and EV3.

The NXT Brick
The NXT is the 2nd generation of LEGO Mindstorms. Before the 2009 update (for the NXT) the NXT original kit included: 3 servo motors, 4 sensors (ultrasonic, sound, touch, and light), 7 connection cables, a USB interface cable, and the NXT Intelligent Brick.

The 2009 update included: 3 Servo Motors, 5 sensors (ultrasonic, sound, 2 touch, and color), 7 connection cables, a USB interface cable, ant the NXT Intelligent Brick.

The EV3 is the 3rd generation of LEGO Mindstorms. The EV3 has 4 motor ports, 4 sensor ports, a USB host port, and a micro SD card slot. The EV3 Education kit includes two large servo motors, one medium motor, and 4 different sensors (ultrasonic, touch, light/color, and gyro). The home kit comes with the same accessories, however it comes with three different sensors instead of four (IR, touch, and light/color). The home edition includes an IR controller as well.

What sets the two bricks apart?
After reading the about the NXT and EV3 bricks, many differences can be found between the two bricks. The EV3 has more motor outputs compared to the NXT. The EV3 kit includes more sensors than the NXT kit. One major difference between the two bricks is the EV3 is compatible with NXT motors and sensors in addition to its own. That is a good reason not to get rid of your old NXT motors, the touch sensor, the ultrasonic (to some degree), the color sensor used in Reflected & Ambient Light Intensity mode. The NXT is only compatible with EV3 motors.

The EV3 has a larger display screen, but smaller text size, and includes a USB host port and a micro SD card slot. This helpful feature can be used to add more storage to the brick or to connect multiple EV3 bricks to one another.

So it is a win-win situation if you have the old NXT kits you can still make use of some of the electronics (and definitely the LEGO® elements in the kits), plus buying an EV3 kit, which offers way more features than the NXT. The EV3 beats the NXT in software compatibility as well (see B2B - Academy: NXT and EV3, they work together....)

 Future posting: Comparing the NXT and EV3 motors!

Wednesday, May 25, 2016

Nite Brite Lite

During this previous weekend, Knights of bots went to Brics~2~Bots Academy. Our Mentor/Coach (L3GoBots Lady) had discovered someone with a program to work the RCX/NXT Lamp with EV3 Programing. She then enhanced the program a bit and given it to us to come up with some new ideas.
  Our task was to build a household miscellaneous that would improve our lives. So one of us came up with a device that would allow someone to wave there hand which would activate the NXT lamps. When someone wakes up it is 99% of the time to use the bathroom or get a glass of water. Their lights are turned off and they can't see anything. So the wave their hand and.... TA DAA, the lights turn on. When the person is finished all they do is swipe their hand and the lights turn off.
We used the following program and made a program that uses the IR Sensor. For Home kits you can use the IR sensor and for Education you can use the Ultrasonic.

The IR Sensor Block has a Threshold value instead of a distance like the Ultrasonic Block. If you decide to use the Ultrasonic instead of the Infrared switch the block in the program as well as the sensor in the design.

We will soon have a new and improve Nite Light which would have a LDD (LEGO© Digital Designer) file which will allow you to see the steps to build the Nite Brite LiteIf you have not downloaded LDD please do so by clicking ->LDD.

The My block we have inside looks like this:

Due to LEGO not selling NXT/RCX Lamps anymore, if you get the EV3 Power Function Lights and the conversion cord 8" or 20" and use the same program. You can purchase it at LEGOeducation.

Monday, April 11, 2016

The Advantages of LEGO Digital Designer

LEGO Digital Designer (LDD)

For all the people that own some form of LEGO Mindstorms, here is some GREAT advice for you. We use a virtual designing program to design all of our LEGO ideas. The name of it is LEGO Digital Designer. LEGO Digital Designer allows its users to virtually design all of their robots/creations. Then, it generates instructions so its users can build their creations. The only problem we have with this program is that it is nearly impossible to design gearing systems with it. Other than that, it is a great way to plan out your potentially AWESOME creations!
If you are interested, here is the link to the downloads page for LEGO Digital Designer.