How to on taking loops from LEGO parts ProPreview

Each year the FIRST LEGO League robotics Competition involves loops. In this video tutorial I will go through the most common way of taking loops, show its disadvantages and suggest another way to do it.

• #47
• 14 Nov 2013
• 9:32

Carabiner

A LEGO Mindstorms construction for taking loops. Uses the same principle as a carabiner.

English

Talking about the FLL competition, we should surely mention loops. In all competitions from the past years there has been a mission that somehow involves loops. The loops are also one of our categories from the mission categorization in episode 25. So, in the next few minutes I'll show you different types of loops and also different ways for taking them.

Before we start thinking about how we can achieve missions that involve loops, we should categorize the different types of loops. First, we have regular loops which look like this. Still, they may differ. The first possible difference is their diameter, the diameter of the tubes. This loop has a smaller diameter than that loop. It can actually go through it. It's not magic. Then we have the height of the loop. As you can see, the black one is higher than the white one. Also we have a difference in the base. What does this mean? For instance, the yellow loop has a wider base and it's more stable than the white one. If you just slightly kick the white one it starts spinning and so on. Next we have objects that do not look like loops but still should be included in this category. And that's mainly because of the tubes of the objects. So, this is the pizza from the 2011 competition or the medicine mission from the 2012 mission or the loops mission like water from the 2013 competition. Here we also have a difference in the diameter. As you can see, this is different from this and from this. The last thing we should consider about loops no matter whether they are regular or not is the height of the upper part of the loop. In the case of the pizza the upper part of the loop is no more than 5 cm away from the ground. Next we have the regular loops or the medicine where we have 10-15 cm from the ground. Next we have the flexibility mission from last year where we have the upper part at 45 cm and also we could have a mission like the loops mission from 2009 where we have something like 20 to 30 cm off the ground. In conclusion, the two things that we should consider are the diameter of the loop and the height at which it is positioned. Now let's see which the most common way for taking loops is. For this purpose I'll use the pizza from the 2011 competition and also our robot. The first way is to attach a crossed axle at the appropriate height. When I run the robot, I can grab the pizza, turn around and the pizza will still be with me. The disadvantage is that if I decide to go back, the pizza will fall. A possible solution is to put something in front of the axle. Now I go and take the pizza but there's a problem. You can easily push the pizza and it may fall. So, I'll use another part. This one. I'll put it on my axle and put the axle back and try again. So, I go, take the pizza with me and when I go back (ops, I've missed it). Still, there is a slight chance that you can catch it like this. Nevertheless, I don't think this is the perfect solution we can think of. Another problem is that when using one axle only, you can easily miss the pizza. Because we aim at the middle of the pizza but if somehow the robot makes a mistake and is 2 cm on the left, it will miss the pizza. A solution is to have more than one axle. I will put these two axles. Again, I'll have to put something in front of them. Like these.