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Topic: Advice for microcontrollers & motor controllers (Read 2381 times) previous topic - next topic

ahmad

I am building a device which will make use of 3 linear actuators, model (LACT12P), the datasheet is found at
http://www.pololu.com/catalog/product/2313/specs
please any recomendations for which programple microcontroller & motor controller is good for this project. can I command the motor controller by the PC direct ? which way is recomanded?
the three actuators will stand in fixed plate and connected by another one at the top, the motion of the top-plate should controlled by commanding the actuators.

thanks
Ahmad

cr0sh


Since this is an Arduino forum, we can say that virtually ANY of the Arduino models and variations
would be suitable for controlling three of these.

You will need an H-bridge type motor controller for each actuator, capable of the 10A stall current @ 12V. 
Pololu and others sell motor controllers in that category.

Pololu, for example offers several motor controllers which take care of some of the overhead,
and they also offer motor driver boards where the Aduino would handle more of the work, etc.

Pololu Motor Controllers: http://www.pololu.com/catalog/category/10
Pololu Motor Drivers: http://www.pololu.com/catalog/category/11


Note that none of those motor drivers are -likely- to have inputs or control systems for the potentiometer position sensors on the actuators (but I may be wrong - I haven't looked over the complete line lately). For these, you will have to hook the potentiometers to the Arduino via the analog input pins, and monitor the position of the actuators in that manner. See this tutorial for more info:

http://www.arduino.cc/en/Tutorial/Potentiometer

As you can see, it's very simple to do...

:)
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

ahmad

thanks for help :)
actually i am new to these things and I am confused in some issues!
I've select the microcontroller (Arduino Mega 2560) it has 16 analog inputs. which is enough to take the pote. signals from the three actuators.
http://store.arduino.cc/ww/index.php?main_page=product_info&cPath=11_12&products_id=71
can I use Arduino Uno model, which has 6 analog inputs? its almost half the price! put the thing is there is 3 wires come out of the actuator pote.!

for the motor controller I've found two models:
1)Cytron 4 Channel 5-26V, 3A Brushed DC Motor Controller, that can take 4 motors, but I'm not sure if it capable of the 10A stall current @ 12V ??
http://www.robotshop.com/cytron-4-channel-5-26v-3a-brushed-dc-motor-controller.html

2)Pololu Simple Motor Controller 18v7 (Fully Assembled), capable of the 10A stall current @ 12V, but I'am confused how to connect the three controllers to the micro controller?
http://www.pololu.com/catalog/product/1372

please if u can advice me which one to use or if u can suggest better choices. :)
I'm sorry for asking too much, i'm really appreciate your advice.
Thanks A lot

Hello.


Note that none of those motor drivers are -likely- to have inputs or control systems for the potentiometer position sensors on the actuators (but I may be wrong - I haven't looked over the complete line lately).


Actually, Pololu has had motor controllers with feedback for over six years now :)  We recommend jrk 21v3 motor controller with feedback for use with those linear actuators.  Just configure the mode and PID constants (the actuator product pages have a link to a settings file for using the jrk with the LACTxP actuators that will configure everything for you) and you get serial (or RC or analog voltage) position control of the linear actuator without needing to close the feedback loop with your Arduino.  There are instructions for doing this at the bottom of the linear actuator product pages.



To the original poster, ahmad:

Those actuators have a stall current of 10 A, but the average current does not get anywhere near stall when they are used within their 110-lb load rating.  The 3 A Cytron controller you linked is underpowered for this actuator (the 3 A rating is a maximum, and the continuous current it can deliver is likely significantly less than that).  This this actuator can briefly draw more than 3 A whenever it starts moving from rest or changes direction, which could damage a controller with a 3 A current limit.  The Simple Motor Controller 18v7 does have sufficient power for this actuator, but it does not support feedback, so you would need to close the feedback with your Arduino if you go this route.  Even though it is more expensive, I think the jrk 21v3 is the best option (or at least it's the simplest) because it basically just turns your linear actuator into a servo, which lets you move on to the rest of your project without having to worry about implementing feedback loops and PID algorithms yourself.

- Ben

cr0sh


Hello.


Note that none of those motor drivers are -likely- to have inputs or control systems for the potentiometer position sensors on the actuators (but I may be wrong - I haven't looked over the complete line lately).


Actually, Pololu has had motor controllers with feedback for over six years now :)  We recommend jrk 21v3 motor controller with feedback for use with those linear actuators.


Interesting and nice to know! Can those controllers be configured in any other manner besides the Windows configuration utility? Does Pololu provide any specs or data on the protocol used by the software?
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

The jrk's graphical configuration utility only works in Windows, but there are other ways to configure the device.  I think David's post on the Pololu forum explains this better than I could (he is one of the primary engineers behind the jrk):

Quote from: David
We don't distribute precompiled Jrk software for Linux, but you can download the Pololu USB SDK and compile JrkCmd, a command-line utility (written in C#) for configuring and controlling the jrk.  You can use JrkCmd to configure the jrk from a configuration file (which you can get from either JrkCmd or the Jrk Configuration Utility).

The complete documentation of the jrk's serial protocol is in the user's guide, but the permanent configuration settings of the jrk can only be changed over USB using control transfers.  For more information on what control transfers the jrk supports and what the protocol is for them, you can see the source code of the Jrk class in the Pololu USB SDK; that source code could be considered advanced documentation for the jrk.  However, if all you want to do is configure the jrk from the command line, you won't need to look at the source code because JrkCmd supports that already.

As for Mac OS: we haven't tried compiling any of the jrk software for Mac OS and can't really support it, but you might be able to get it to work because both mono and libusb work on the Mac.


Note that the all of the jrk's settings are stored in non-volatile memory, so one option is just to find a Windows machine and use the graphical utility when you want to reconfigure the jrk, which probably won't be very often once you have it set up for a particular application.

Does this adequately address your questions?

- Ben

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