What's current technology for PC-based motion control
I don't do a lot of posting on any of these forums but have found the information quite useful. I have a project that needs to retrofit a new PC-based motion control system to a optical inspection system. The current system has an industrial PC with a Delta-Tau system but I was told that it's far to old technology to consider using.
What is "current technology" for this type of motion control? When I last looked at it over 10 years ago, there were companies like Delta-Tau and Galil that made cards and stepper/servo drives. They had their own programming languages that were reasonably easy to use.
Are these still the "go-to" companies to use? Is there anything more cost-effective that's been developed? About the only current custom automation in this shop is a small Automation-Direct PLC, I haven't looked to see what they have to offer. I was told by someone that there are super-easy to integrate USB systems out there, is that true?
I'm not looking for anyone to do my research for me, just hoping that someone out there with a lot of knowledge and experience can get me pointed in a good direction.
What is the work envelope?
What type of motion is required? (i.e. fixed points or does it need the ability to program positions often?)
There are now several types of linear actuator packages with built in positions in the drive, no pc required, just drive it from any plc.
Without knowing the type of mechanicals involved, or more specifics on what you want to do it's hard to suggest things.
There are pc options out there also. Motion Guru I think would be more knowledgeable about those. I typically only deal with industrial controls, so I am limited in my knowledge of pc systems.
I use Galil for all my machine vision stuff and the majority of machine control tasks but I've been working with them for a very long so I have libraries I can just plug in to an application. It's hard to beat Delta-Tau for high end big machine complicated 6-10 axis stuff, this is top of the line and I know of nothing better.
Originally Posted by The Dude
Integration time eats up money fast. Working with a system you know and that programs in an environment you are comfortable with saves tons of money.
What you use may depend a lot on what your time is worth. You could do this using Mach running on the pc for control if you wanted to.
The pc (x86) architecture is very poorly suited to real time motion control on it's own. Much easier and less time consuming to offload the work to a separate control CPU.
Usually optical measuring is just point to point work but you need to be sure the stage has stabilized before taking the picture. Brushless servo systems that are "hunting" +/- one count will drive ya nuts. Linear scale feedback is normally needed and this can get messy. Both Galil and Delta-Tau handle this. What is gonna do the vision processing side? Are you using existing motors and drives?
For simple low resolution one axis positioning there are lots of options in packaged "smart" drives. USB is too slow for most of my needs, you may want to consider a dedicated ethernet channel to the controller.
Disclaimer: Having no knowledge of the details of your app the above may be all wrong.
As an example, a smart camera could talk directly to a smart drive, totally eliminating the pc from the system.
Last edited by CarbideBob; 01-07-2011 at 08:27 PM.
Sorry this took so long for me to respond to. For some reason, this forum doesn't notify me of responses to my posts, even though my email address is correct and I check off that I want to know when people respond (and no, it's not going to junk mail either).
Anyway, this is a very small work envelope, maybe 12" x 12" x 4" at the most. All it needs at the moment is to manually jog around so that measurements can be taken at various points. The original system was built to run "programs" but the present need is just to run manually. I'm wondering if the PC even needs to be running for the joy ("jog") stick to manually move the axes around as it's connected directly to the drive package, not the Delta Tau card. Any thoughts on that?
I've asked my client to take the PC into his IT guy to see if he can get it runnign and see what kind of "user interface" software may be running on it.
Any other thoughts, if any of the above makes sense?
Can you drive stepper motors with encoders (MPG) ?
If all you need to do is manually jog around, is all you are asking for is a joystick/MPG and a readout of some sort?
Originally Posted by 3t3d
I'm not familiar with "MPG", could you enlighten me? Otherwise, yes, we could make this as simple as the joystick to jog around and a digital readout of position of the axes. Keeping the programmable capability would be nice for future applications but just getting it going is what's top priority now.
MPG Manual Pulse Generator.
Basically, an encoder, with a dial on it, and maybe a spring detent to make it "Click" 100 time per revolution. Machine tools have an MPG to jog the axes around. The dial might have 0-100 numbers on it, and each click of the dial will move the Axis a certain amount.
Here is a quick search of Ebay to show some examples.
Thanks, there's no MPG on it. Just a joystick that interfaces into a box in the rack that sits above the Servo cards (which are made by Western Servo Design).
I didn't think you had MPG's, but was suggesting that if the drivers took step and direction commands, then the MPG and the drivers might be all you need, for now.
That is going in the opposite direction from the original question, "What is the current state of the art technology?", but possibly appropriate/adequate for the described task.
The Delta Tau card doesn't need the PC to run - it can run stand alone just fine. I have a few Delta Tau systems over at Chris King Cycle group in Portland running with a laser engraver for marking bicycle head sets . . . all stand alone, simple with manual jogs and then a simple I/O interface to the laser. Have a few more in Portland doing everything from sharpening saw blades to welding sintered diamond blocks onto chainsaw chain.
DT is a capable motion controller - but it has never been a true PC based control . . . it has it's own processor and doesn't rely on the PC for any aspect of its operation except for the power supply and they give you separate terminal blocks to power it up if you want to run stand-alone.
We have a Delta Tau in one of our EDM machines, it is the Umac version which is controlled by USB. Works fairly well, runs a 7 axis high speed EDM hole driller.
Have you found a solution for your needs? I have two Galil DMC-1840 (4 axis) motion control sets that are comprised of a DMC-1840 DSP motion controller board that was reman'd by Galil and has never been removed from the anti-static envelope, ICM-1900 breakout board and interconnection cable. I have a third set that is currently installed in my office desktop and it has been used for software developement. I wrote a complete full featured CNC frontend for the Galil DMC bus series motion controller boards. The CNC frontend has all of the typical CNC control functions such as Work Coordinates System, Tool Length Offsets, Cutter Radius Offsets, Cutter Compensation, Drill Cycles, Manual Data Input, Jog, Graphic Tool Path Viewer and etc. At the current state of development the program will read G code, translate G code to DMC board language, feed the translated G code to the DMC buffer and run the G code/DMC code. Due to the fact that there is no encoder feedback the program uses the encoder error to display the position of the axis. Very simple to change code to read encoder feedback. The CNC frontend was delveloped to the point where I needed to have a machine integrated with a Galil DMC controller to assist with developing a motion profile. The hard part of the CNC frontend has been completed and the final development would be simple if you 'really wanted to do it'. I emphasize that because I failed on the first two times that I tried to learn to program and it was simply due to the lack of 'really wanting to learn'. My inspiration was purchasing Camsoft. I installed Camsoft and after a brief examination I uninstalled it and sold it through eBay. That's when I realized that I had one choice and that was to write my own CNC frontend. Unfortunately health issues interrupted the project and I lost interest.
Buy the Galil hardware and get 1000s of hours of software development for free. I would like to sell all of the Galil hardware in one sale. Make an offer if your interested.
Hi, well sort of. The need went away but I may be working on another system for another client where we would need a motion control system. It's likely at least 6 months out but I will revisit this if it pans out and maybe inquire as to if you still have it.