Hello everyone,
I’m new, and joined because I need help with controlling a linear actuator. The actuator is actually going to be used on my truck to control the position of the vanes on a variable geometry turbo. This exact setup has been used, but it only is wired to a momentary switch, so it isn’t precise and is difficult to get in the same position everytime.
The actuator isn’t directly controlling to turbo, but is just acting as a stop, or travel limiter. I esentially want to be able to wire up a 3 position switch and have each position correspond to a set point in the actuators range of motion.
Example:
2" stroke linear actuator
Switch down (or position 1) = 2"
Switch middle (or position 2) = 1.5"
Switch up (or position 3) = 1"
I’m not stuck on those values obviously or the exact switch setup, but would ideally like 3 set positions I can switch to. I am currently using this actuator on a momentary switch:
surpluscenter.com/item.asp?item=5-1554&catname=electric
https://www.surpluscenter.com/ENLARGED/p5-1554E1.jpg
12 VDC LINEAR ACTUATOR
New takeoffs VALEO model 24021541 linear actuator originally made for use in electric automotive seats. No clutch or limit switches. Permanent magnet type motor. Threaded output shaft has 13/16" x 1-3/16" x 13/16" steel block with 3/8"-18 tapped hole in side.
SPECIFICATIONSVoltage 12 VDC
Amps 1.5 no load
Travel 15/16"
Extension time 3 seconds full travel
Rotation reversible
Enclosure Fully enclosed
Duty Intermittant
Mount 1/4" dia. pin hole at base end
Shaft 7/16" dia. 8 T.P.I threaded rod
Overall size 5-1/2" x 2-3/8" x 4-3/4"
Shpg. 4 lbs.
Thanks for all of your time, I would really love it if I can make this work. I’m interested in learning from all of you, as electronics are definatly my weak point.
Coleman,
Thank for the reply, any and all input is much appreciated.
I will look into that, but it sounds a little over my head, I’m very new to electronics. Also I’m trying to keep the costs minimal.
I have another idea. There are 3 settings I need: closed, nearly closed, and about middle. Nearly closed will be the one that is normally used.
Can I wire in an led that will light up when the arm reaches the nearly closed position? Then another for the middle. The closed will be easy to figure out, just keep going after nearly closed till it stops.
Maybe use a magnet on the linear actuator arm and a reed switch where I want the nearly closed position to be?
I’m not too familiar with reed switches and LEDs. How would I wire a simple circuit like tha up on my truck?
Do I need a fuse, or relay?
The actuator you selected does not have position feedback, so how would a system “know” the position? There are other linear actuators which have position feedback and allow you to specify intermediate positions. Given that your actuator does not have feedback, you might consider timing the motion so it gets to “about halfway”. To do this, you would need to add a microcontroller and a motor controller. You would then connect a switch or potentiometer to the microcontroller and create a program to control the actuator’s speed based on the potentiometer position.
Another option would be to add a linear potentiometer to the side of the actuator to give you position feedback. You would need to find a way to mount physically so the elements do not affect it. You would then still need the microcontroller and motor controller, as well as a rotary potentiometer to control the position.
That’s certainly an option - have a circuit which goes HIGH when it detects something like - a magnet, a white strip, a gap etc.
The functionality you describe (having three switches that trigger thee different positions) can probably be achieved without microcontrollers but you will need to implement the logic using switches (reed, relays, or any other kind).
This will require some thinking, some ingenuity and some experimentation. We can get you started with the process but you will need to learn about the different components and how they can interact together to complete the project.
We believe that you will need these things:
]Three switches (duh… 
) /:m]
]A way of sensing where the actuator head is (either using bumpers arranged in a sort of ladder, reed switches, light sensors with markers). You need to know if the shaft is between position 0 and 1, 1 and 2, 2 or 3. /:m]
]Using that information you will need to create logic functions. For instance, if the head is between 0 and 1 and button A is pressed, the motor polarity is forward and the motor is ON. /:m]
You will probably need to make a drawing or diagram of your setup to understand it better. Once you made sure you covered all the possibilities with your logic, you will need to think about the wiring of the switches and sensors.
Keep us posted about your project!
) /:m]