Linear Actuator Control

[Phantom_Cyclist 4]

I am slowly gaining knowledge of building big rigs.  I have a tow truck to build  next.  For a number of reasons I do not want to use the Tamiya actuator kit to raise and lower the arm.  I can see loads of linear actuators and understand enough to understand the different specifications but I cannot find how to control them.  They have a single wire pair and depending on which way round they are connected they travel to one end or the other.  How is this voltage reversal obtained in an RC set up?

[Otis311 416]

May I ask what your reservations are with the Tamiya actuator set? Aside from the high cost of course.

I suppose the simplest method of control would be an electronic speed control. The only thing is that it would not know the endpoints and you would have to be careful to stop when the limit is reached. The Tamiya set looks like it takes care of this with micro switches. This could all be done similarly with an Arduino and some programming.

 

[Phantom_Cyclist 4]

2 hours ago, Otis311 said:

May I ask what your reservations are with the Tamiya actuator set? Aside from the high cost of course.

I suppose the simplest method of control would be an electronic speed control. The only thing is that it would not know the endpoints and you would have to be careful to stop when the limit is reached. The Tamiya set looks like it takes care of this with micro switches. This could all be done similarly with an Arduino and some programming.

 

Mostly the high cost and I was thinking about other parts of trucks that move - crane arms etc. and thinking about how to make them move.  The actuator I have seems to have limit stops built in.  Its the voltage reversal I can't work out how to do.

[Ziddan 1063]

Im relatively certain one can get what are essentially servo electronics without centering/low power ESC that run any motor within the limit of the circuitry, at rest it does nothing, giving the high/low signal will move the motor in either direction.

Ive made those things out of servos that have broken gears, take apart the servo, fix the sensing potentiometer in its centre position and then connect whatever motor to the wires, for turret rotation on a RC tank.

If that motor has a screw attached to its output and there is a nut captive on the threads it can then act as a linear actuator.

End point detection requires something that is smarter, like the suggested arduino or some purpose build circuit.

I guess linear actuator could just be set up like regular servos tho, with a linear potentiometer along the travel of the actuator, or a geared down regular potentiometer, if a radio channel is bound to a two position switch it would then send high or low, properly stopping at the ends of it range, though i cant recall seeing this. ADDITION: Did a search, there are apparently linear servos that work pretty much like i describe.

I built a wrecker addon for a friends WPL truck, it was built using WPLs v3 board which features a built in ESC which can be bypassed for a stronger one using a regular servo lead for motive power, a channel for a steering servo, a channel that can go high/low (usually for a 2 speed gearbox) and an analog 5v output for an auxiliary accessory which is at 0v at rest and can go to + or - 5b (usually used for a winch).

He built the truck as standard, motor channel for the motor, steering channel for steering servo and two position channel for a gear shift servo.
To make the wrecker addon work i hooked two leads to the aux output and routed one of its wires through a switch that got pressed by the gearshift servo (at the same time as it switched the gears).

And then made a wire harness splitting out into two.

Allowing for connecting two geared motors, which to be controlled being chosen by switching gears.

In the case of this wrecker addon one is controlling boom lift and the other is the line for the hook.

Some info on servo to esc conversion:

 

And for turning a regular servo to contineous rotation: 

 

[Tamiya Fan 1 443]

I would go with Tamiya's Actuator. Because it is disigned for it easy peasy. (with MFC) Unless your are going to make all the pieces to work. (winches, boom etc...) Which can be done by the way but becomes a wiring nightmare. Alot of channels on the radio etc... There are actuators that do have limits built into them. The company is from Canada if they are still around? Sorry I forget the name of them. The site (forum) that had their name is not working anymore. They did carry 2 kinds, one with stops built in and one with out. (the control would be set up different) (ESC)They also had them in different lengths per application and strengths.( which ment slower for stronger) Run a search, maybe you can find them? Or you may be using them all ready.

Thought I would throw that your way.

[Phantom_Cyclist 4]

Thank you for your comments.  Much to ponder about how complicated my truck will be.

 

[Tamiya Fan 1 443]

The site was reachable today? The name of the actuator company is "Actuonix Motion Devices Inc".  They have alot and I do beleive Linear is what you want. They used to have only square style but I think round ones now. Which look more realistic.

Good Luck!

[Phantom_Cyclist 4]

On 2/26/2025 at 9:44 PM, Tamiya Fan 1 said:

The site was reachable today? The name of the actuator company is "Actuonix Motion Devices Inc".  They have alot and I do beleive Linear is what you want. They used to have only square style but I think round ones now. Which look more realistic.

Good Luck!

I had found them but thought they were aimed at commercial companies rather than hobbyists. I will contact them as it sounds like I was wrong.

Thanks.