Improving FLL Robot Game. Scissors mechanism for Lifting Pro Preview

The final way for lifting our box robot is by using a scissors mechanism. In this Episode, we would discuss the benefits and advantages of this mechanism.

  • #452
  • 20 Mar 2017
  • 4:18

Scissors mechanism

No, this is not the "official" name but is a nice name by which we could refer to this robotics mechanism. The are two gear wheels and two beams connected in a certain way. One of the gear wheels is fixed.

Planetary Mechanism

One of the gear wheels is fixed and the other is rotation around it. It is a planetary mechanism. Because one of the wheels orbits around the other as a planet. We are fixing the star wheel with an additional blue pin. 

 

Robot Lifting Attachment With a scissors mechanism

For the FIRST LEGO League 2016-2017 Animal Allies we prepared an attachment for lifting the robot. The idea of the attachment is to show how you could lift the whole robot with a system of gear wheels, levers, and scissors constructions.

Built mainly from LEGO Mindstorms EV3 parts but could probably be constructed from NXT sets.

English

The final way in which we'll try to lift our Box Robot is using a scissor mechanism. Let's discuss the benefits and most of the advantages of this mechanism for lifting our Box Robot. The final mechanism looks like this. Here we can rotate and it will lift the whole robot and the robot is right here. But to develop this whole attachment it is important to start from the very very simple think of a scissor mechanism. Again, we are using the gear wheels the large 40 teeth gear wheels. And we have two of these gear wheels. We have one of the gear wheels that is freely rotating using the axle and we have the other gear wheel that's fixed and by fixed I mean that this gear wheel cannot be rotated. You can't rotate this gear wheel. Let me just remove this. We have the axle and this axle is through the center of the gear wheel and then we have this blue pin here and this blue pin fixes the whole wheel and you cannot rotate this wheel. You can see it from the back. The idea here is that we have this wheel fixed on one of the beams - the white beam. Then we have the second wheel and this second wheel can be rotated and now the mechanism works like this. When I rotate the gear wheel we lift two of the legs. If we imagine these two gray beams are the legs, when we rotate like this we lift the legs. And we can even push to the ground. And this will make the whole attachment move up and then forward which is exactly the behavior that we need for attaching our Box Robot to the mission model. Just move forward and then attach. And then we can rotate back and get the legs back. And that's the principle of the mechanism. The interesting thing here is that you can extend this mechanism. You can, for example, place longer beams right here on the place of the gray beams and this will make the whole mechanism lift the robot up to more Lego units. And you get to a larger height. And it is an interesting mechanism because you can get this to work in a very stable way. You can construct it in a very durable way.

We can achieve the same result with other gear wheels and for these gear wheels we have the maximum distance that is not actually the maximum. The distance between one of the axles and the other axle always stays the same because this axle rotates around this. It draws a circle around the axle. And the distance between the two axles is always the same. And it's this number of Lego units. It's 6 Lego units. So, the distance always stays the same which is a nice feature that we can use for actually lifting our Box Robot.