Author Topic: Controlling linear actuator from microcontroller  (Read 2469 times)

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Offline ErikYTopic starter

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Controlling linear actuator from microcontroller
« on: August 08, 2012, 01:45:18 PM »
I am playing around with different actuators for a project I have in mind, and I bought a high speed linear actuator.

This has a positive and a negative wire only, and no data connection wire.

Much like a DC motor.

Originally, I was thinking I could run this like a motor using an h-bridge, in particular the SN754410, on my $50 robot board that I have, which is Webbot's version using the 6v and the 9V battery sources, one for the motors and one for the mcu.

Then I realized that the linear actuator needs 12 volts, not the ~6 usually required for a DC motor, and it can require up to 9 amps.

So, I don't think I can use the SN754410 nor the $50 robot board.

So I was going to make anew board, kind of a spinoff of the $50 robot board, but using the 328P instead of the ATmega8, and with a 12V battery source (2 6V in series) for running the linear actuator.

What I am wondering is if I can run the red linear actuator wire to a 12V power source, and the black linear actuator wire to a i/o pin on the mcu, so that when the pin goes low, it is connected, and when the pin goes high it is disconnected.

My hope is that since the power is coming from the 12V batteries, and not the mcu, I will not fry my circuits.

Would this work?

If not, can anyone help me out with how I can do this?

Offline Soeren

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Re: Controlling linear actuator from microcontroller
« Reply #1 on: August 08, 2012, 04:27:49 PM »
Hi,

This has a positive and a negative wire only, and no data connection wire.

Much like a DC motor.

It is a DC motor.

If it hasn't got end stop switches, you need to use over current detection to break the power when at either end.


What I am wondering is if I can run the red linear actuator wire to a 12V power source, and the black linear actuator wire to a i/o pin on the mcu, so that when the pin goes low, it is connected, and when the pin goes high it is disconnected.

Let's pretend that you never suggested pulling 9A through an I/O pin ;)
Besides, even if it could handle the current (eg. by a transistor in-between), how about reversing direction?

Here is a cheap way to get both directions and not frying your controller in the process :)  http://That.Homepage.dk/PDF/PWM+Relay_4_Motor_Ctrl.pdf
The relay makes the equivalent of an H-bridge and the MOSFET makes it PWM
able (so that you can control the speed of it. If you don't need that, a relay (with a driver is all it takes - plus an over current detector if there's no end stop switches as mentioned (Now you wish you had included a link :P)
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 ErikYTopic starter

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Re: Controlling linear actuator from microcontroller
« Reply #2 on: August 09, 2012, 07:55:59 AM »
Hi,

This has a positive and a negative wire only, and no data connection wire.

Much like a DC motor.

It is a DC motor.

If it hasn't got end stop switches, you need to use over current detection to break the power when at either end.


What I am wondering is if I can run the red linear actuator wire to a 12V power source, and the black linear actuator wire to a i/o pin on the mcu, so that when the pin goes low, it is connected, and when the pin goes high it is disconnected.

Let's pretend that you never suggested pulling 9A through an I/O pin ;)
Besides, even if it could handle the current (eg. by a transistor in-between), how about reversing direction?

Here is a cheap way to get both directions and not frying your controller in the process :)  http://That.Homepage.dk/PDF/PWM+Relay_4_Motor_Ctrl.pdf
The relay makes the equivalent of an H-bridge and the MOSFET makes it PWM
able (so that you can control the speed of it. If you don't need that, a relay (with a driver is all it takes - plus an over current detector if there's no end stop switches as mentioned (Now you wish you had included a link :P)


Soeren,

Thanks much for your reply!

OK, I spent a lot of time trying to understand the circuit you showed me.

First off, the linear actuator does have built in limit switches, so that is a plus.


I have a few  questions that I just don't understand and cannot figure out.

Is SV1 what connects to my mcu?

I am assuming the V+ and V- are dedicated 12V from a battery source?

There is also a circle with a rectangle around connecting to transistor bd140, what is that?

Also, the 4 circles on the corners of the silksreen, are those for mounting the board?

For the DPDT relay, what is the 351 representing?

I THINK that is it for now, I think I get the rest of it.

Once again, thanks!





« Last Edit: August 09, 2012, 08:02:34 AM by ErikY »

Offline Soeren

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Re: Controlling linear actuator from microcontroller
« Reply #3 on: August 10, 2012, 07:24:39 PM »
Hi,

First off, the linear actuator does have built in limit switches, so that is a plus.
Yes, you can feed them to I/O lines w. pull-up either internal or physical resistors from the I/O to Vdd (+5V or whatever you use). The other end of the switch should go to ground (twisting the wires going to each switch around 3 times per inch will make it more immune to motor noise). You could feed both switches to a single line, if your pin "budget" is tight and then keep track of direction in software (assuming you either extend or retract it completely on power up, to know where it is).


Is SV1 what connects to my mcu?
Yes, the layout is made for "Berg pins" (the pin rows w. square pins that's used in almost all controller boards) - soldered wires would work if needed.


I am assuming the V+ and V- are dedicated 12V from a battery source?
There's no V-, but you probably mean the 0V and if so, yes, and the relay should be 12V as well.


There is also a circle with a rectangle around connecting to transistor bd140, what is that?
Assuming you mean on the overlay (I stared at the schematics for a couple of minutes and didn't know what you were on about ???) - it's the BD140 itself. It's because of the symbol I used was for a transistor bend down flat on the board and the circle is the "no-go" area, had it been inside the copper pour, but it should be mounted standing up.


Also, the 4 circles on the corners of the silksreen, are those for mounting the board?
Yes.


For the DPDT relay, what is the 351 representing?
It's just the relay symbol I used (a relay called 351). If you intend to make a PCB, wait until you have a suitable relay (they come in all sorts of pinouts), then, if it doesn't fit the one I used, give me a link to a datasheet containing the physical measures of it (and it's pinning) and I can modify the layout to suit.

If you can't find a DPDT relay that can handle the needed current, two SPDT or DPST can be used instead.

For larger currents, automotive relays are quite cheap compared to their current handling capacity.
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 ErikYTopic starter

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Re: Controlling linear actuator from microcontroller
« Reply #4 on: August 10, 2012, 07:35:23 PM »
Hi,

First off, the linear actuator does have built in limit switches, so that is a plus.
Yes, you can feed them to I/O lines w. pull-up either internal or physical resistors from the I/O to Vdd (+5V or whatever you use). The other end of the switch should go to ground (twisting the wires going to each switch around 3 times per inch will make it more immune to motor noise). You could feed both switches to a single line, if your pin "budget" is tight and then keep track of direction in software (assuming you either extend or retract it completely on power up, to know where it is).


Is SV1 what connects to my mcu?
Yes, the layout is made for "Berg pins" (the pin rows w. square pins that's used in almost all controller boards) - soldered wires would work if needed.


I am assuming the V+ and V- are dedicated 12V from a battery source?
There's no V-, but you probably mean the 0V and if so, yes, and the relay should be 12V as well.


There is also a circle with a rectangle around connecting to transistor bd140, what is that?
Assuming you mean on the overlay (I stared at the schematics for a couple of minutes and didn't know what you were on about ???) - it's the BD140 itself. It's because of the symbol I used was for a transistor bend down flat on the board and the circle is the "no-go" area, had it been inside the copper pour, but it should be mounted standing up.


Also, the 4 circles on the corners of the silksreen, are those for mounting the board?
Yes.


For the DPDT relay, what is the 351 representing?
It's just the relay symbol I used (a relay called 351). If you intend to make a PCB, wait until you have a suitable relay (they come in all sorts of pinouts), then, if it doesn't fit the one I used, give me a link to a datasheet containing the physical measures of it (and it's pinning) and I can modify the layout to suit.

If you can't find a DPDT relay that can handle the needed current, two SPDT or DPST can be used instead.

For larger currents, automotive relays are quite cheap compared to their current handling capacity.

Soeren, Thank you much for your help! Much appreciated!

I am going to order some parts and try this out.

Offline ajit.nayak87

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Re: Controlling linear actuator from microcontroller
« Reply #5 on: December 10, 2012, 05:45:50 AM »
i wanna know above ckt designed for how much current rating

I have linear actuator @24 v dc 10A running over battery .

i wanna controlled the action trough MCU 5v ttl @ 50ma

how could above ckt help me
Best Regards

Amps

Offline Soeren

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Re: Controlling linear actuator from microcontroller
« Reply #6 on: December 10, 2012, 07:03:51 AM »
Hi,

i wanna know above ckt designed for how much current rating

I have linear actuator @24 v dc 10A running over battery .

i wanna controlled the action trough MCU 5v ttl @ 50ma

how could above ckt help me
The circuit can easily handle 10A, but I don't think it's right for your application.

Rather than spreading your requests over several threads of different topics, why don't we keep it in the thread you started - it's easier to keep track of it all 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 ajit.nayak87

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Re: Controlling linear actuator from microcontroller
« Reply #7 on: December 10, 2012, 07:40:36 AM »
can you suggest me the link or the circuit for the our application.
I will be more thankful if you share me the  Design part for 24v 6A driver provided with short ckt protection
Best Regards

Amps

Offline Soeren

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Re: Controlling linear actuator from microcontroller
« Reply #8 on: December 10, 2012, 06:13:12 PM »
Just answer the questions in the thread you started and I'll help you, but I won't work it in two threads.
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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