Concentric LACT4P-12V-20 Linear Actuator with Feedback: 4" Stroke, 12V, 0.5"/s

September 6, 2013 – 11:09

This 12 V linear actuator can be used in a variety of heavy-duty applications. The motor has 20:1 reduction gearbox that gives the actuator a dynamic load rating of 110 lbs (50 kg) and a maximum speed of 0.5 in/s (1.3 cm/s), and it is rated to withstand up to 500 lbs when not moving. Limit switches at each end make the actuator easy to control over its full range of motion, and the worm drive ensures that the shaft will hold its position even when unpowered. This version has a 4-inch stroke and a built-in potentiometer for position feedback.

Compare all products in Concentric LD Series Linear Actuators.

Concentric linear actuator without feedback, opened to show gears.

Overview

The LD Series of linear actuators by Concentric International (formerly Iowa Export-Import) are 12V DC gearmotors that use a worm drive to move a shaft back and forth along its length. The worm drive ensures that the shaft will hold its position even when unpowered. Two limits switches safely stop the motor at either end of its range, while integrated diodes allow it to reverse direction after reaching a limit point if the supplied voltage is reversed. The actuators are mostly metal, and the entire case is sealed to protect against dust and water (rated IP63).

Connecting the bracket to one end of a Concentric LD linear actuator.

The Concentric LD series linear actuators are available in a variety of lengths and with optional potentiometers that are linked to the shaft position, for use in feedback systems. Several lengths are also available in two gear ratios: 5:1 and 20:1. The 5:1 versions have lower load ratings—34 lbs dynamic, 450 lbs static—but allow for higher speeds, up to 1.7 in/s. The 20:1 versions are slower—up to 0.5 in/s—but are rated for dynamic loads up to 110 lbs and static loads up to 500 lbs.

We also have generic linear actuators that can generally be used as less expensive alternatives to the ones from Concentric; the table on our linear actuator category page can help you find the actuator with the combination of speed and force that best meets your project’s requirements.

Mounting brackets are available for attaching the actuators to a structure; two are required for each actuator. Our bracket for generic linear actuators also work with the LD actuators, although they are a little loose.

Concentric linear actuator with feedback, 4" Stroke (LACT4P), shaft fully extended.

Using the actuator

To test-drive the actuator, simply connect a power source of up to 12 V to the motor leads. Reversing the applied voltage will reverse the direction of motion. A motor controller or motor driver is required for electronic speed and direction control. We recommend our Jrk Motor Controllers for use with the feedback actuators and the Pololu Simple Motor Controller 18v7 for controlling the actuators without feedback, though many of our other motor controllers and motor drivers are capable of powering this actuator.

These actuators have a stall current of 10 A at 12 V, but they will, on average, draw far less than this when used within their load ratings. They draw around 500 mA with no load an can exceed 3 A at their maximum rated dynamic load, so we have found they generally work well with our lower-power jrk 21v3 motor controller with feedback (see the bottom of this page for more information using this controller for closed-loop linear actuator position control). Note, however, that the actuators can briefly draw close to their full stall current when abruptly started or on a sudden change of direction. Such current spikes can be dampened if you take steps to limit the acceleration of the actuator (many of our motor controllers offer optional acceleration limiting).

Source: www.pololu.com

40 corrections per second

2007-12-06 12:27:37 by iamlucky13

What they mean when they say that, is that the computer reads the input states 40 times per second. Each time it reads the input states, it compares the values to expected values, then uses an algorithm to determine the desired control states. We now have computers with processing power to do it hundreds of thousands of times per second...much much faster than the response times of the systems involved and sometimes faster than any actuators can actually respond.
The algorithms are engineered from known factors like lift, drag, center of gravity, etc. Then some poor schmuck of a test pilot takes the plane up and determines if the engineers got it right or if it needs a little tweaking (hopefully not a lot of tweaking)

Fieldbus for steam-drain control  — InTech
Ultimately, when you minimize signals, you improve the overall efficiency and performance of the network.


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