Linear Actuator with Feedback and 2GǦ Stroke (LACT12P)

Linear Actuator with Feedback and 2″ Stroke (LACT12P)

This 12V linear actuator can be used in a variety of light-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 2-inch stroke and a built-in potentiometer for position feedback.
The LD Series of linear actuators 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 limit 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 IP65).
Mounting brackets are available for attaching the actuators to a structure; two are required for each actuator.

LACT12P Specifications:

• Concentric item number: LACT2P-12V (sometimes also written LACT2P-12V-20)
• Nominal stroke length: 2″ [5.1 cm]
• Actual stroke length: 1.97″ [5.0 cm]
• Retracted length: 7.68″ [19.5 cm] (from mounting hole to mounting hole)
• Extended length: 9.65″ [24.5 cm] (from mounting hole to mounting hole)
• Weight: 39 oz [1.10 kg]
• Gear ratio: 20:1
• Rated dynamic load capacity: 110 lbs [50 kgf or 500 N]
• Speed at 12 V, no load: 0.57 in/s [14.6 mm/s]
• Speed at 12 V, max load: 0.48 in/s [12.3 mm/s]
• Feedback potentiometer

Using LACT12P Linear 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 and 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).

Actuator leads:

Each actuator has a 3-foot-long cable. On actuators with feedback, this cable is terminated with special female connectors as shown in the left picture below, one for the three potentiometer leads and another for the two power leads. These connectors match male versions on the extension cable for LD linear actuators. Actuator versions without feedback have two unterminated, stripped power leads as shown in the right picture below. Linear actuators without feedback do not have cables that are compatible with the linear actuator extension cable.

Using a jrk motor controller with a linear actuator:

The feedback feature included with our jrk motor controllers make them a great solution for precisely controlling our linear actuators with feedback. Our settings file for the jrk configuration utility makes setup easy, eliminating the need to calibrate the feedback and tune the PID constants. To get started, follow the steps below:

1. If you have not already, read through the Jrk USB Motor Controllers User’s Guide and download its drivers and configuration software.
2. Connect your jrk to a PC with a USB cable and launch the configuration utility. The red LED should be on, and the green LED should be flickering quickly.
3. Download the jrk 21v3 settings file for use with LACTxP (1k txt). The settings in this file work with any length actuator that has a feedback potentiometer (model LACTxP), and they were tested on the jrk 21v3, which is powerful enough to drive these actuators in typical applications. These settings should also mostly work for the higher-power jrk 12v12, though a few of them (e.g. current calibration) might need to be adjusted.
4. In the configuration utility, choose File → Open settings file (Ctrl + O), and navigate to the location of the settings file you downloaded in step 3.
5. Click on the PID tab of the configuration utility and verify that the proportional and derivative coefficients are not zero. If they are zero, the settings file was probably not loaded properly and you should try performing the previous step again.
6. Click “Apply settings to device”.
7. With your power supply off, connect your linear actuator to your jrk using the connections shown in the picture to the right. The picture shows a jrk 21v3, but the connections will be the same if you use a jrk 12v12.
8. Turn on Power.
9. On the Error tab, choose “Clear Errors”. The “No power” and “Feedback disconnect” errors will clear. The red LED will turn off, and the yellow LED will blink slowly.
10. On the Input tab choose “Set Target” to move your actuator to the target position.

While this setting file gives precise control over most of an actuator’s range, you might find decreased performance very near the extremes due to the limit switches. If your project requires better control near the actuator’s limits, you might need to recalibrate the feedback settings for your particular actuator.

Linear Actuator Documents:

• 3D models of the Glideforce light-duty linear actuators
• Jrk G2 21v3 settings for LD 5:1 linear actuators
• Jrk G2 21v3 settings for LD 10:1 and 20:1 linear actuators
• Datasheet for Glideforce Light-Duty (LD) Linear Actuators