Firgelli Linear Actuators

[Silverback01]

I'm working with some Firgelli linear actuators http://www.firgelli.com/products.php and they are potentiometer-controlled. Is there a way to control something like this through a microcontroller? It would be a serious waste of weight (for an airplane) to have to use a servo to control a pot, which controls the linear actuator.

Thanks!
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John

[PCM programmer]

You need to post the part number of the actuator that you're using.

This one, for example, has a built-in microcontroller, and has the option
to use 4 different interfaces. One of those is the standard RC servo
interface. You don't need potentiometers to control it. A PIC can do it.
http://www.firgelli.com/pdf/L12_datasheet.pdf

CCS has some driver code to generate the servo signals:

[Silverback01]

The model is the PQ12. The ones that were ordered were the potentiometer-controlled ones which were used for a demo. I am trying to find out if they can be implemented in the robot in order to save a little money, but I may have to reorder them with the RC servo interface.
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John

[Ttelmah]

As far as I can see, there is no such thing as a potentiometer controlled version!.
The 'P' says it has a potentiometer _output_. However the input, seems to 'auto switch' between four different interface standards, and will automatically detect a RC servo input, or 0-5v. Either could be driven very easily by a PIC. If you choose a PIC with a PWM output, and add a reasonable integrator to the output of this, you can use this as a 0-5v source in place of the potentiometer. Then to get real accuracy, use the output from the potentiometer built into the unit, and adjust the PWM to give the required position.

Best Wishes

[Ttelmah]

Sorry, I was reading the data sheet in PCM programmer's reply.

However if these are positionable using a pot, then the answer stands. They must have a controller fitted.

You need to find out the letter/number sequence after the PQ-12 part. This is a bit like saying "it's a Ford [spam]". It is the letters and numbers afterwards, that say the trim level, engine, gearbox etc. etc.. These are what matter in terms of control.

_All_ can be controlled by a PIC. The most complex would be a 'bare' unit, requiring H-Bridge control (much easier on a PIC with a more sophisticated PWM unit). The simplest one with a controller already present.

Best Wishes

[Silverback01]

I've been emailing the company today and still haven't made much progress. The datasheet I was sent for the PQ-12-20-30-A http://www.firgelli.com/pdf/PQ12_datasheet.pdf shows a five-wire ribbon cable--three of which are tied to a potentiometer, and two for power. They have a control board (CIB) http://www.firgelli.com/pdf/CIB_datasheet.pdf that can apparently take an input from a standard R/C receiver and do a bunch of hocus-pocus on it to get the actuator to move where the user wants it to. I have their control board and there are a lot of components on it in order to make it robust. (Note the sliding potentiometer on the right of the CIB.)

However, since my application is for a very small UAV, the board eats power and subtracts usable payload weight and volume. Firgelli does have a larger version of this actuator (but heavier), which is the L-12 and has an option to plug directly into a receiver. I may have to make the sacrifices in weight, and cost to save volume and headache and go with the bigger one.

In a nutshell, the five wires on the PQ-12's engineering drawing is the problem area.

Thanks again.
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John

[Humberto]