Two-speed resolver employing differential reduction techniques

Abstract

A two-speed resolver system wherein the rotor of a fine brushless resolver which is directly connected to the shaft to be instrumented is connected to the rotor of a coarse resolver so that the rotor ofthe coarse brushless resolver rotates at a proportional but different rate than the fine resolver and the electrical output of the fine resolver which represents the position of the input shaft is fed to the electrical input on the coarse resolver and combined with the mechanical input to the coarse resolver to provide a signal out of the coarse resolver which indicates a predetermined fraction of angular rotation for each revolution of the rotor of the fine resolver. The disclosed two-speed resolver system utilizes brushless resolvers wherein the electrical connections to the rotors are through brushless rotary transformers. Two gears having a different number of teeth can be used to couple the rotor of the fine resolver to the rotor of the coarse resolver. The difference between the coarse resolver mechanical rotation and the fine resolver electrical output when subtracted by the coarse resolver determines the fractional rotation indicated by the coarse resolver for each revolution of the fine resolver rotor. The fine resolver is connected to provide sine and cosine representations of the mechanical angular input to its rotor. These sine and cosine angular indications can be fed to the stator windings or rotor windings on the coarse resolver and the coarse resolver can be connected to provide an output signal which represents the difference between the revolution of its rotor and the sine and cosine input from the fine resolver. This output can be made to indicate a predetermined number of degrees of rotation for each revolution of the input shaft.