> > with an encoder on the motor shaft and a linear encoder on the axis gantry > could linuxcnc be configured to detect a stall > maybe as simple as a loose motor connector >
Putting encoders on a stepper is an obvious idea that occurs to everyone faced with positioning errors, but it turns out that nagging details make it not so good in practice. The basic problem is that there's not much one can do after a following error: the steppers tend to be run with maximum rated current already, so it's not like we can drive them harder to catch up. Also, the problems with steppers tend to occur because we drove them into difficulty such as mechanical resonance or binding---the solution tends to be to slow down, not drive harder. Additionally, by nature steppers can only screw up by one step, so a real-time course correction is not really possible, it's only good for 'oops, we're screwed'. In conclusion, stepper drivers/motors are cheap and simple, and work reliably within their design envelope. Encoders make them complicated and expensive for little gain, so they tend not to be used. ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
