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Creating Linear motion for your NXT projects - Part 2

Following on from yesterday's piece about linear motion in robots.....
Today we will continue with a third and elegant way to achieve linear motion: Using the linear actuators.

1. What is a LEGO Linear actuator?

Linear actuator (LA) is a brand new piece of hardware just released by LEGO, that is used to turn rotational motion of a motor into linear motion similar to a piston. It is just longer than an AA battery when it is not extended and it sort of looks like this:

2. How do I use it?
Using a LA with a NXT kit is pretty intuitive. Just plug in an axle of a NXT motor (or a Power Function (PF) motor using the NXT adapter cable) to a LA. Write a simple program in NXT-G to drive the motor. I will post an example program in NXTLog ASAP. Programming does not need to be very precise as to the number of rotations - I did it long enough to do about 28 rotations to extend the LA fully - and it works fine. If you put too many rotations, the internal clutch handle it pretty well as you can see in the video below.

Here is something I knocked up within minutes of opening the box with a LA using a PF motor and a couple of gears and a NXT. I also used the bracket that came with the LA to make the connection easier.

3. Examples of LA's in action.

To demonstrate how cool the new LA is, I created a model that uses both the LA and the old pneumatic pump (that shipped with last year's LEGO TECHNIC Mobile Crane) and created a fully working fire extinguisher.

Warning: The use of pneumatic pump with water is not recommended. Also be cautious when working with fire and water.

4. Where can I get my LA?

You can not currently buy this item on its own. It currently ships with two models that came out this month and it is now shipping - so you should be able to order it.

Here are the two models that has a LA: 8294 (telescopic Extender), 8295 (Excavator).

What is inside a Linear Actuator?

I could not bring myself to break a brand new LA apart. However, I did find an excellent post by Conchas in the TechnicBRICKs blog a few days ago that did just that. It is well written and definitely worth a read if you want to know more !!


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