Dave wrote: > How would that SSI to quadrature encoder work? The nice thing about > SSI is that when the power goes on, the motion system knows exactly > where it is without homing or moving. > That only works if a memory is kept alive to remember the rotation count (assuming shaft encoders). If a linear encoder, the number of bits becomes unwieldy pretty quickly, and then you go back to some kind of cyclical count plus a multiple counter. > I'm trying to find an encoder now. The best I have found far on the > surplus market is a 360 count per rev unit which is not very good. I'd > like to find at least a 4096 count per rev unit or better yet a linear > unit that I could actually use to mockup with a hydraulic cylinder. > A 4096 count/rev unit would need 12 optical sensors, also the higher the count, the more likely you would start to get artifacts due to alignment of the sensors. I would guess these units might get real expensive at the higher resolution.
The Fanuc aA64 encoder has an absolute position with 1024 counts/quadrant for commutation, and a position count with 16 bits resolution on angle plus a 16-bit rotation count. It uses a quadrature optical disc with interpolation. There is also a 15-bit angle version and a 20-bit version. This seems to be the sanest way to make such an encoder. Jon ------------------------------------------------------------------------------ vRanger cuts backup time in half-while increasing security. With the market-leading solution for virtual backup and recovery, you get blazing-fast, flexible, and affordable data protection. Download your free trial now. http://p.sf.net/sfu/quest-d2dcopy1 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
