Real airplane analog instruments are based on differential resolvers. I created software and hardware for interfacing them to

my sim (see the HSI video), but it was based on a PIC18 and performance was not adequate.

Reading shaft position using differential resolvers is done as follows:

 

  • Generate a sin wave and apply it to the primary winding
  • Read the signal on the two secondary windings and analyze amplitude and phase relative to the sin wave applied
  • There is a 1:1 relationship between phase on secondary windings and shaft position. Use an arcsin table to lookup position

 This must be done pretty quickly, depending on the instrument RPM. I found some limitations on PIC18 to do this properly, so

I will be implementing in in a dsPIC. Will post pictures and samples shortly thereafter.

Some links about differential resolvers:

http://en.wikipedia.org/wiki/Resolver_%28electrical%29

Schematic for the board (work in progress)

 

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Last Updated ( Wednesday, 25 February 2009 17:49 )