The previous rubber bands video showed a way to trigger the rubber band without a motor. This video gives one more idea on how to lift an axle and in this way release the rubber band. Use the idea for you LEGO Mindstorms robot constructions.
- 28 Jun 2015
- FIRST LEGO League (FLL), Construction, LEGO Mindstorms Robot Attachments
- Ev3, Rubber band, Fll 2014
Previous videos on rubber bands:
Instructions for building the robot:
Building instructions for the Rubber Band Attachment
In this video, we continue building attachments that use rubber bands from the Lego Mindstorms EV3 set. And today's attachment, again, won't use any motors. And the rubber band will be triggered entirely with the push of the attachment.
This here was the attachment that we built in the previous episode. One thing that we improved first it was a little difficult to load the rubber band. As you can see, doing this with fingers, it's a little tricky. So, we've built this small mechanism and we can load the attachment in the following way. We add this to access here, then we just push the rubber band, and we have the attachment loaded as you can see right here. Now, we are again solving a mission model. The challenge is to trigger the mission model by pushing the element over here, just as a reminder. Now, if we release the rubber band, it will fire the small mission element and will solve the mission, like this. Now, how can we do this without the use of a motor? Because we don't want to use the motor, so that we can have the motor free for other missions. We must find a way to push on this attachment and to lift the axles here. And we've come up with this solution. Now, we add axles, so that one of the axle is a little bit longer. And when we push to the mission model, as you can see here, we've pushed to the mission model. Then, we see that those model- this model moves. We push again. And now, if we add the attachment like this, we would have the desired behavior. Now, if we move- when we move the robot, we program the robot. Then we push to mission model, and as you can see, as we push the axles here, they are lifted. And so, the rubber band will be released and we can fire the element. And it's a pretty simple, elegant solution, it will work-- at least on our side, it works all the time. And so, it's quite straightforward. So again, we push to the mission model and we can see that this model here is lifted. Now, let's see this in action. First, we've added some additional parts to the competition robot. You can find instructions for building this competition robot below the video. Now, we have the whole attachment and this is the first part of the attachment, this is the second part. We take the model for lifting, we place it like this. Then we add the attachment, something like this. Then we load it. And now, the only thing that we should do is load the rubber band like this.
Add the mission model. And again, the details of how we reach the mission element are not the subject of this video. We program the robot. It moves on the field. It reaches the mission model. For example, something like this. Then it slightly pushes. And when we move, we fire. We can do this again. One important thing is that this model here, it moves when we fire with the rubber band and we must stop it. So, we've added a small additional part that stops the model from moving. If we don't have the part, let's see what happens. Again, we move on the field, we reach-- let me just load it. We move on the field, we reach the mission model, then we start pushing. And we don't have the additional part here, so, the model will probably be fired like this. Push it. So that's the purpose of this additional part here. As a conclusion, it's an interesting attachment. You can find the instructions for the attachment below the video. It's a general mechanism for using the rubber bands. And you can use the ideas whenever you need to use rubber bands, and you need to trigger them without the use of a motor. You can use the motor for other missions.