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:

video

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!

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