Stuart Stevenson wrote: > Gentlemen, > In my limited experience with the handwheel control on this machine I > see what I consider over run. I know it is the accumulated pulses the > machine has not completed. When the handwheel is turned faster than the > machine is able to respond the actual position lags behind the commanded > position. When I stop turning the handwheel the machine continues and > finishes the motion. I believe it would be far better if the control > would truncate the command and stop the machine as soon as the handwheel > is stopped. If this is already available would you tell me how to make > it work? If it is not yet available I would very much like to see it. > This to me is almost a safety issue. All my other machines stop the > motion as soon as the handwheel stops regardless of the speed the > handwheel has rotated. The accumulated motion is cut off. When I want to > move any of my other machines an exact amount by the handwheel I must > move the handwheel slow enough to allow the machine to keep up. Also, on > my other machines I can whip the handwheel and spin it very fast. The > machines stop as soon as the handwheel stops. > I was able to move the table in the x positive direction, stop the > handwheel, let the table move a little bit after I stopped moving the > handwheel, move the handwheel in the negative direction and cause the > machine to move in the negative direction before reaching the final > commanded postion of the x positive move. It added the x negative move > to the commanded position and when the commanded x position became more > negative than actual position the machine reversed direction. This is > very confusing as the operator would not be able to keep up with the > final position until the machine reached it and stopped moving. > I can see problems. Broken tools, scrapped parts, and other nonvalue > added modifications. If this is not a safety issue it is very much a > training and financial issue. > Thank you very much for the response and guidance received up to now. > I very much appreciate your attention.
This is one of those "can't please all the people all the time" things. If I have my handwheel set for 0.010 per click, and I turn it 50 clicks, I expect the table to move 50 x 0.010 = 0.500 inches, no more and no less. If I turn it those 50 clicks in 1/4 of a second, but it takes the table 1 second to make the move, that doesn't change my expectations. I can see the logic behind your approach. I hope you can see the logic behind mine. It is clear that they are incompatible. I also hope you understand why I'm not willing to change it from one approach to the other. Support for both, at the option of the machine builder, would be ideal, and we can investigate that possibility. However, there are some details that need resolved before your approach can be implemented. You want the machine to stop when you "stop" turning the wheel. But defining "stop turning the wheel" is not easy. The software runs 1000 times a second. If you are turning a 100 click wheel at 4 revolutions per second, that is only 400 clicks per second. Which means more than half the time, the software will see no clicks. Does that mean you stopped? Of course not. Suppose you have the scale set to 0.010 per click, and it takes your machine 0.050 seconds to accelerate from a standstill, move 0.010 inches, and stop again. Also suppose that you are turning the wheel slower than one click every 0.050 seconds. When the software sees a single click, it needs to start a move that will take 0.050 seconds. The next 50 times it runs, it will see no movement of the wheel. Should it assume you stopped (you did, after all) and therefore abort the move before it finishes? Or should it give you the precise 0.010" move that you asked for with that single click? This is just the beginning of the questions that would need to be answered to implement your approach. I don't want to dismiss it, but you'll need to define your desired behavior much more precisely, and in a way that can actually be done, before we can do much about it. Regards, John Kasunich ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
