Wednesday, 25 January 2017

What Are Micro Linear Actuators?



micro linear actuator


If you're new to the world of robotics, you might be wondering "what are micro linear actuators?" Simply put, they are small devices that convert rotary motion into linear motion. They work in much the same way as large-scale actuators, but are physically smaller in size. This makes them more suitable to tight spaces and applications where weight must be kept to a minimum.

There is no hard and fast rule for what makes an actuator 'micro' but generally speaking, micro linear actuators have a stroke of less than 300mm and offer less than 100lbs of maximum force.

You'll find these devices in thousands of applications across dozens of industries including robotics, aerospace, medical devices and radio control. RC linear servos are also compatible with arduino and thus becoming more popular with the DIY crowd.

Benefits

Of course the main benefit of micro linear actuators is their relatively small size. Size, weight and cost restrictions have kept linear actuators out of consumer products for a long time. Actuonix changed that in 2005 with the development of the first affordable, reliable micro linear actuator.  

Electric micro linear actuators are slowly replacing pneumatic and hydraulics as the preferred solution for all types of automation applications.

The main advantage of Actuonix micro linear actuators is their tiny size. They're also very simple to mount compared to standard rotary hobby servos. Our micro linear actuators are also capable of higher forces. With max forces of up to 67lbs, Actuonix devices have the power it takes to drive your projects.

Design

Electric micro linear actuators fall into one of two categories: inline or side by side. Inline actuators are typically thinner and a little bit longer than their side by side cousins. They are ideal for small spaces. Below is an example of an inline actuator and a side by side actuator




Side by side actuators tend to be more powerful due to the added space for a larger motor. They have a larger cross section but also have a shorter installation length, which can be better for some applications.   

The shaft of a miniature linear actuator can be either circular or square in shape. They will typically be constructed of aluminum or another high-quality metal. There are exceptions here, our PQ12 is constructed of plastic and is tough as nails with a max force of over 11lbs!

Difference between micro linear actuators and servos

Micro linear actuators and linear servos are very similar and the term you use can depend on the industry you're working with. R/C and robotics hobbyists will be more familiar with the word 'servo' as rotary servos have been popular in those spaces for many years. The term actuators tends to be used more by industry and the scientific community.  

For the purposes of this article, I'm referring to all products as 'actuators' with the exception of our 'R' series, which is a direct plug-and-play replacement for rotary servos. The 'R' series are micro linear servos.

Control

Most micro linear actuators are a simple 2-wire 12v device that is operated by reversing the polarity of the applied voltage. Simple and effective. This is great for some basic automation projects.
Actuonix Motion Devices leads the micro motion industry when it comes to control options. We offer 4 different control options off the shelf to better accommodate the needs of our clients.

S Series

Our S series is the simplest micro linear actuator that we offer. As described above, they use a 6V or 12V input and are controlled by reversing the polarity. Our S series actuators come with end of stroke limit switches to prevent motor damage.
The P series micro linear actuator, has an internal position feedback sensor instead of limit switches.  This sensor allows you to connect a position controller of your choice to automate the actuator.  We offer a control board called the LAC board which allows you to adjust the speed, set end limits and adjust the sensitivity.

R Series

Our R series linear servos are a direct plug-and-play replacement for regular rotary servos. They will work with most R/C receivers as well as arduino, VEX and Raspberry Pi.
The I series micro linear actuator has an embedded internal position controller that will allow you to send a variety of position commands which the actuator will follow. Designed for the industrial and scientific market, it can accept an analog voltage, PWM voltage, 4-20 mA current from a PLC, and RC signal inputs.

What are Micro Linear Actuators used for?

The potential applications for micro linear actuators are endless. Any project that requires linear motion but has space or weight restrictions is an ideal candidate. Below, I've listed a few examples of industries or groups that commonly use micro linear actuators to give you an idea of how versatile they are.

  • Robotics – OEM companies and hobbyists alike use micro linear actuators in everything from mass-produced robotic hands to carefully-crafted, home-built R2D2 models with full functionality.
  • Radio Control – Linear actuators are a popular choice among RC enthusiasts. Sliding canopies, retractable landing gear, excavator and bulldozer control as well as automated dump truck boxes are common
  • Arduino – Our micro linear actuators drive thousands of arduino projects from animatronic Christmas and Halloween displays, to auto-closing chicken coops.
  • Industrial – Thousands of potential applications


Choosing the right Micro Linear Actuator for your project

Start with stroke. Measure how far you need the actuator to drive to accomplish your goal. Next is force or speed, how much force do you need or how fast does it need to move?  Remember these two factors are linked because for any actuator the more load you add, the slower it will go.  Use our speed vs. force charts to pick the gear ratio that is most suitable for your application.

Now that you have a good idea what you need in terms of physical capability, you need to decide how you will control the actuator. Do you want a basic 12V reversing polarity setup, or do you need to control your end limits. Do you plan to use arduino?

If you need help choosing the correct micro linear actuator for your project or product, send us an email or call our sales department and we'll be happy to help you choose the micro linear actuator that will best suit your needs.
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