> I agree with Stuart's analysis that the processes discussed seem not to > need real time response, but I don't think the original poster has ever > spelling out just what his multi-station system has to accomplish. > > Regards, > Kent
This has been a very interesting discussion. I can see several directions that could lead to where I want to be. My goal is building a modular assembly system that would perform similar functions to a typical pneumatic pick & place assembly system, but using stepper motor drive and EMC for control. Traditional assembly systems perform motion using pneumatic actuators, with needle valves controlling velocity and mechanical stops setting stroke limits. A PLC provides the logic to control the directional valves. Setting up the system involves lots of machining of little brackets for holding actuators and sensors, fiddling with stops and needle valves, and tweaking PLC logic and timers. EMC control would replace all that with a single package of three or four axes of motion and simple G-code programming for each pick & place station. Traditional systems typically used a large "dial plate" or indexer that cycled assemblies between stations when the PLC determined that all individual stations had completed their actions. I would still need this higher-level synchronization between individual stations, whether they are separate computers, separate cores, or nine axes running on one EMC instance. If you've never seen one of these type of assembly systems at work, you can see videos of small ones built by my manufacturing students last year: http://www.youtube.com/watch?v=Ytz1Fvt1SYE (pneumatic pick & place / hard automation) http://www.youtube.com/watch?v=bDL4FT_6ZSA (same project using 6-axis robots) The idea is to have the production throughput of the hard automation, with the flexibility and ease of design & fabrication of the robot version. Tooling needs to be added to the end of each station, just as is needed for the robot or for the hard automation system. Instead of an indexing dial plate, my new scheme would use this type of track, with carriages moved along by strategically placed stepper motors with pinion gears, and short lengths of gear rack on the side of each carriage: http://www.youtube.com/watch?v=xn26Pj66X5M (initial verification of the concept) For my immediate testing purposes, I'll use separate D510MO's for each group of four axes, and read up on the joints_axes_3 branch of EMC2. Thanks again for the enlightening discussion. -- Ralph http://engr.wallawalla.edu/engr480 ------------------------------------------------------------------------------ Create and publish websites with WebMatrix Use the most popular FREE web apps or write code yourself; WebMatrix provides all the features you need to develop and publish your website. http://p.sf.net/sfu/ms-webmatrix-sf _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
