On 22 December 2011 16:45, Anders Wallin <anders.e.e.wal...@gmail.com> wrote:
> a dream project of mine would be a telescope mount. To minimize > tracking error one should measure the rotation directly on the geared > axis (not the motor) and one wants maybe 4 million pulses (22 bits) > per rev for that. That sounds like a job for a resolver, rather than an incremental encoder. I am not sure which chip the Pico converter uses, but the same family go up to a claimed resolution of 2 arc minutes. http://uk.rs-online.com/web/p/synchro-resolver-to-digital-converter/7094709/ Not inexpensive, though. Couple that with a multipole resolver and you might get what you want. > want an encoder with 12 to 14 bits of sine-shaped counts, i.e. up to > 16k-counts/rev. How big a circle would that require? That depends mainly on the sensor. The sensor I am intending to use is 75 lines per inch, so 16k would be a 68 inch circle.. There is a 150 lpi version, for a mere 3-foot encoder. -- atp The idea that there is no such thing as objective truth is, quite simply, wrong. ------------------------------------------------------------------------------ Write once. Port to many. Get the SDK and tools to simplify cross-platform app development. Create new or port existing apps to sell to consumers worldwide. Explore the Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join http://p.sf.net/sfu/intel-appdev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
