Jump to content

  • Log In with Google      Sign In   
  • Create Account

jms bc

Member Since 07 Dec 2012
Offline Last Active Dec 15 2014 04:32 PM

Posts I've Made

In Topic: Need help with a project (AC motors and programming)

14 October 2014 - 10:11 PM

The video doesn't work for me -- says it is private.

 

Servo implies that there is an encoder on the shaft. Motor can be any kind.

 

Steppers have distinct coils, so with appropriate driving signal there are discrete stable points along a single rotation - steps. Not the smoothest motion but cheap, easy and can bear a load -- with these you move things into position, then let everything settle down before doing something. And you don't need an encoder because you can keep count of the steps, assuming the mechanism is well made.

 

If you want to do something while in motion then you probably want a dc motor. Smooth motion but more work and expense typically. Harder to hold still under load. Needs an encoder on it if you want to know position. 

 

I've remembered since my first post that once programmed a multiaxis controller made by a company called Newport that would coordinate along a defined path. It would interpolate as needed, you just defined points and time. You don't need any custom software or hardware -- I bet you could do it yourself if you had the manual.

 

The harder part might be the mechanics of the device you have in mind.


In Topic: Need help with a project (AC motors and programming)

14 October 2014 - 05:31 PM

Reads like a typical industrial motion control application. When I was doing similar things with optical equipment (lasers, crystals, mirrors, gratings, diodes), I used dc or stepper motors w/ gear box. The controllers were usually commercial products (Newport,Compumotor,Galil...) though sometimes I used boards built in house. Don't know why you think you would need to modify the boards.

 


having the motor communicate with a computer somehow by means of splines
 

 

I don't know what that means. I think you refer to some kind of position or velocity feedback.

 

Might be helpful for you to look at commercial products to get a feel for what you can get off the shelf. Most of those controllers have a way to compose complex motion with multiple axes. Also, look at sites for homebrew robotics, lots of info there.


In Topic: Critique my approach to writing RAII wrappers

09 September 2014 - 12:25 AM


RAII isn't a new term

 

yeah, I should have said "new to me"...just didn't really pay much attention before C11 and have been confused by the literature...lazy maybe...backing out...


In Topic: Critique my approach to writing RAII wrappers

08 September 2014 - 08:35 PM

So this thread went from "How is my RAII" to "What the hell is RAII". Interesting comments.

 

 

Barney says:

 

"The name of the game here is to get allocation out of the way so you don't see it"

 

"the main tool for resource management is constructors and destructors"

 

A standard container that, say, resizes itself during its lifetime (allocating/deallocating memory outside of constructor/destructor) would therefore not be RAII, right? Or is that being too literal? 

 

To me, if what Bregma says isn't true, then RAII doesn't mean anything new, it is just a reminder to program properly. Sussing out ownership is just sane programming. 

 

A practical application could do wonders for this debate. I approach from the perspective of someone with a resource intensive program -- once I've instantiated the RAII-abiding objects I need without issue, I can count on having the resources ready, ie, the program won't fail on a resource allocation after that point. Could be memory, a serial port, an electron gun, drone...they are all ready to go. My initial interpretation of RAII was along these lines.


In Topic: How to add a Console and Output to an existing New Empty Project

08 September 2014 - 07:19 PM

assuming visual studio, open the project property pages. linker-->system-->subsystem. Choose console and add a main() entry point for the program.

 

int main( void ){

//good enough

}

 

how did you create the empty project though? Looks like you have to pick windows,console, dll, or static lib when you create a new project.


PARTNERS