A friend showed me this today, not powered up yet: https://www.kickstarter.com/projects/tropicallabs/mechaduino-powerful-open-source-industrial-servo-m
At first I was confused, it says it's a stepper, but with an encoder, and lowers or disables drive current when not needed. Or you can freewheel it and it'll maintain the coordinate system. It cannot stall without the system knowing, and a stall won't corrupt the coordinate system. But there's no mechanical connection to the motor, it's this new AS5047D high speed, high resolution magnetic rotary position sensor: http://ams.com/eng/Products/Magnetic-Position-Sensors/Angle-Position-On-Axis/AS5047D You glue a magnet to the rear of the motor shaft, and keep the sensor like 1/4" away. Note it not only counts delta, it knows absolute rotor position. Gives 2000 counts/rev. That's enough that it could effectively show rotor phase through a single fullstep, which would allow for more stable electrical control of stepping. There's an initial calibration phase that drives a phase so it knows where the TDC of Coil A is in absolute position. They set it up so it powers down and freewheels, except it will hold its position by powering coils when needed. It can also reduce current to product only the torque needed to follow the step commands, instead of always operating at full current. Well, my mind is blown! Danny ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
