Author Topic: Linear actuator controller  (Read 1123 times)

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Offline simplistikTopic starter

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Linear actuator controller
« on: August 19, 2011, 03:49:19 PM »
Howdy folks first post! I am currently making a Rc controlled lawnmower (v2.0) and would like the deck height to be adjustable via an (8 amp 24 volt) Linear actuator ,I have the mechanics part all worked out but I am having a difficult time trying to locate a schematic and or device that can control the actuator forward and reverse with one channel of my receiver either pot/switchable channel.

I did purchase a double switch from DE http://www.dimensionengineering.com/DoubleSwitch.htm in hopes I could control it via relays but did not read it all the way through before making the purchase.
edit** I am moreso looking for a DIY than an off the shelf product. ;)
« Last Edit: August 19, 2011, 03:51:41 PM by simplistik »

Offline rbtying

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Re: Linear actuator controller
« Reply #1 on: August 19, 2011, 04:37:24 PM »
Use an H-bridge to control the actuator, with transistors and diodes rated for the motor. You can use an R-C circuit to convert the PPM signal from the R/C receiver to analog, which can be fed into a PWM circuit (555 timer would work) to control the speed of the motor.

Offline Soeren

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Re: Linear actuator controller
« Reply #2 on: August 20, 2011, 08:44:29 PM »
Hi,

[...] device that can control the actuator forward and reverse with one channel of my receiver either pot/switchable channel.

Since you have no use for speed control whatsoever for this, you can use 2 automotive relays (one for each direction) and a single proportional channel arranged so that moving the stick (or whatever) one way will make it go forward and v.v.
You'll need a microcontroller to interpret the servo signal from the receiver, so that pulses below eg. 1.25ms triggers one relay and pulses above eg. 1.75 ms activates the other.
If you need to slow the actuator down a bit a simple PWM (with a 555 and a power transistor) can be put inline with the supply.


I did purchase a double switch from DE http://www.dimensionengineering.com/DoubleSwitch.htm in hopes I could control it via relays but did not read it all the way through before making the purchase.

Bad description. Took me a while to see that it's just a single DPDT relay. Had it been a true dual relay unit (as it appears to be advertised), it would have worked.


edit** I am moreso looking for a DIY than an off the shelf product. ;)

How are you with programming a microcontroller then?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline simplistikTopic starter

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Re: Linear actuator controller
« Reply #3 on: August 21, 2011, 09:36:01 AM »
Initially the relay setup was what I had in mind when buying the relay from DE , but as you found out after I bought it its a single dpdt relay. However I do have an arduino and have tried to decode the signal coming from the receiver via a script, (no idea where i found the script) but I kept getting different signals every time while running the script.

I do not know how to write program in C+ I purchased the Arduino to learn but never got around to it as other projects just kept popping up.  ;D

Offline Soeren

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Re: Linear actuator controller
« Reply #4 on: August 22, 2011, 03:58:39 PM »
Hi,

However I do have an arduino and have tried to decode the signal coming from the receiver via a script, (no idea where i found the script) but I kept getting different signals every time while running the script.
Strange, but there's a lot of example code out there.


I do not know how to write program in C+ I purchased the Arduino to learn but never got around to it as other projects just kept popping up.  ;D
There is a library called "ServoDecode" that you should be able to change (only the output needs to be changed to your needs AFAIK). You could see it as an exercise in programming.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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