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View Full Version : [Question(s)] How to control 3 linear actuators by computer?



Leaw
05-30-2010, 01:56 AM
I've planned to build a machine to use in my research.
It requires 3 Linear actuators :
- First part consists of two linear actuators that move 10 kg object in vertical axis (range 5 cm) and horizontal axis (range 10 cm).
- Second part consists of one linear actuator that moves small object in vertical axis (range 5cm). This part's movement is synchronized with the first part's movement.

So, I decide to use
First Part
- 2 Inch Stroke 110 LB Linear Actuator for moving 10 kg object in vertical axis
http://www.trossenrobotics.com/store/p/5373-2-Inch-Stroke-110-LB-Linear-Actuator.aspx
- 4 Inch Stroke 110 LB Linear Actuator for moving 10 kg object in horizontal axis
http://www.trossenrobotics.com/store/p/5183-4-Inch-Stroke-110-LB-Linear-Actuator.aspx (http://www.trossenrobotics.com/store/p/5373-2-Inch-Stroke-110-LB-Linear-Actuator.aspx)

Second Part
- 2 Inch Stroke 110 LB Linear Actuator for moving small object in vertical axis
[/URL][URL]http://www.trossenrobotics.com/store/p/5373-2-Inch-Stroke-110-LB-Linear-Actuator.aspx (http://www.trossenrobotics.com/p/figelli-L12-50mm-210-1-Linear-Actuator.aspx)

Specs sheet : http://www.trossenrobotics.com/productdocs/Linear-actuator.pdf (http://www.trossenrobotics.com/productdocs/Linear-actuator.pdf%29)

However, I don't know what controller I should use.
(My requirement is to use computer to adjust speed and stroke of linear actuators in order to create moving pattern.
Another requirement is to program machine to move continuously with different moving pattern.)
Would you mind giving me any advices?

LinuxGuy
05-30-2010, 12:03 PM
However, I don't know what controller I should use.
(My requirement is to use computer to adjust speed and stroke of linear actuators in order to create moving pattern.
There is a link to the appropriate controller at the bottom of the product page.


Another requirement is to program machine to move continuously with different moving pattern.)
Would you mind giving me any advices?
From what I can tell by reading the data sheet, these actuators don't have continuous movement available, but can move to one of three preset positions. You could substitute a relay or switch for the switches on the controller after you remove it, and this could be controlled by a micro to open and close the switches under program control.

Beyond that, I don't have any other advice.

8-Dale

zoomkat
05-30-2010, 03:16 PM
The below actuators have internal pots that could make position indication much easier, but at a significant cost increase. Sliding pots or similar could be adapted to the standard actuator since the movement will be fairly small. You could work up an H-bridge setup to turn the actuators into a linear servo, but it would be DIY. Linear actuator servo setups are available, but they want a lot of $$$ for them. For control, if you go the linear servo route, a servo controller could be used. You could use something like an arduino for control if you want to use relays for power control instead of an H-bridge.

http://www.firgelliauto.com/default.php?cPath=109

darkback2
05-30-2010, 03:56 PM
I'm pretty sure that is the same actuator.

Leaw
05-31-2010, 05:32 PM
One more question; Can I use Linear actuators as RC servo motors so that I can use Phidgets AdvancedServo 8-Motor to control them?

darkback2
05-31-2010, 07:41 PM
I don't think so.

In a servo there is a potentiometer which is turned by a motor and is connected to a board. The board has a chip on it that can read the voltage from the potentiometer, and compares that to a signal sent by the servo controller.

With the linear actuators you are looking at, the potentiometer and the motor are not connected electronically. From what I read there is a limit switch at each end so you won't break the linear actuator, and the potentiometer's voltage should change as the linear actuator moves, but the internal board from a servo is not present so the actuator cannot be controlled in the same way.

You could try something like this:
http://www.trossenrobotics.com/p/phidgets-motor-control-hc.aspx

coupled with a digitizer of some sort to read the potentiometer.

Check out this tutorial on a gripper with pressure sensitivity. Might help a bit.

http://forums.trossenrobotics.com/tutorials/how-to-diy-128/build-a-robot-gripper-with-force-feedback-2284/?catid=searchresults&searchid=6700

Hope this helps.

DB

darkback2
06-02-2010, 01:38 PM
Here is the thing you are looking for. Seams you can use a standard servo controller and power supply with these. That way you could use a phidgetservo 8 and be done with it.

http://www.servocity.com/html/heavy_duty_linear_servo__115__.html

Hope this helps.

DB

zoomkat
06-03-2010, 11:16 PM
If you are a DIY type, you might be able to drive the linear actuator with the below H-bridge and servo internals.

http://www.pololu.com/catalog/product/924/resources
http://www.hobbypartz.com/topromisesg9.html