Method and apparatus for determining angular velocity

Claim 3

A method for determining the angular velocity of a rotor in a resolver as defined in claim 1, wherein said rotor is an electromagnet having an excitation winding, further comprising the steps of exciting said rotor with direct current from a high impedance source, exciting said stator at output terminals thereof with the signals by which output signals thereat are being modulated to obtain said third signal C, thereby developing a fourth signal D representing the function cos ((t)+Qt) across said excitation winding, multiplying said fourth signal D by said third signal C to form a fifth signal C.D, and demodulating said fifth signal to provide a signal proportional to angular velocity with proper sign.

Claim 4

A method as defined by claim 2 wherein said fourth signal D is compensated for a steady-state component of phase shift in said resolver to provide a signal D'' representing the function cos (Qt+(t)+ lambda ), where lambda is the varying component of the phase shift caused by changing resolver parameters, operating on each of the signals C and D'' separately to form square waves that are positive for signal amplitudes greater than zero and negative for signal amplitudes less than zero, detecting the phase difference between said square waves to provide a resulting signal that is greater than zero for a phase difference of one polarity, and less than zero for a phase difference of another polarity, and operating on the resulting signal representing that phase difference to provide for said signal proportional to angular velocity a sign signal that is positive when the resulting signal is greater than zero and is negative when the resulting signal is less than zero.

Claim 5

A method as defined by claim 3 further comprising the steps of multiplying the third signal C by said sign signal to provide an alternating signal E, demodulating the signal E by rectifying and filtering, and multiplying the demodulated signal E by said sign signal to provide as an output signal a signal proportional to angular velocity with proper sign.

Claim 6

A method as defined by claim 4 including the steps of averaging said resulting signal before operating on said resulting signal to provide said sign signal, thereby eliminating effects of uncompensated phase shifts of said stator coupling.

Claim 7

Apparatus for determining the angular velocity of a rotor in a resolver having a stator which produces output signal A and B of respective amplitudes (d/dt) phi sin phi and (d/dt) phi cos phi , where phi is the angular position of said rotor, comprising: means for generating first and second synchronized signals representing respective functions -sin Qt and +cos Qt, where Q is a constant frequency and t is time; means for multiplying said signal A by said first signal to obtain a third signal representing the value -A sin Qt; means for multiplying said signal B by said second signal to obtain a fourth signal representing the value +B cos Qt; summing means for adding said third and fourth signals to obtain a fifth signal representing the value -A sin Qt + B cos Qt; rectifying means connected to said summing means for receiving said fifth signal and providing a sixth signal proportional to the absolute value of said fifth signal; and filtering means connected to said rectifying means for receiving said sixth signal and providing a direct current signal the amplitude of which is proportional to the absolute value of angular velocity of said rotor.

Claim 8

Apparatus for determining the angular velocity of a rotor in a resolver having a stator which produces output signal A and B of respective amplitudes (d/dt) phi sin phi and (d/dt) phi cos phi , where phi is the angular position of said rotor, comprising: means for generating first and second synchronized signals representing respective functions -sin Qt and +cos Qt, where Q is a constant frequency and t is time; means for multiplying said signal A by said first signal to obtain a third signal representing the value -A sin Qt; means for multiplying said signal B by said second signal to obtain a fourth signal representing the value +B cos Qt; summing means for adding said third and fourth signals to obtain a fifth signal representing the value -A sin Qt + B cos Qt; rectifying means connected to said summing means for receiving said fifth signal and providing a sixth signal proportional to the absolute value of said fifth signal; and filtering means connected to said rectifying means for receiving said sixth signal and providing a direct current signal the amplitude of which is proportional to the absolute value of angular velocity of said rotor.

Claim 9

Apparatus as defined in claim 6 wherein said rotor is an electromagnet having an excitation winding, said apparatus including a system for determining a proper sign for direction of rotation of said rotor, comprising: a high impedance direct current source connected to said excitation winding of said rotor; means for exciting said stator windings at said output terminals at which said signals A and B are provided with the respective signals by which output signals thereat are being multiplied to obtain said fifth signal, thereby developing a seventh signal across said excitation winding representing the function cos ((t)+ Qt); and means responsive to said fifth signal and said compensated seventh signal for producing, in cooperation with said rectifying and filtering means, said direct current signal to represent the absolute value of angular velocity and direction of rotation of said rotor.

Claim 10

Apparatus as defined in claim 7 wherein said last named means comprises: means for operating on said fifth signal to form a first square wave that is positive for signal amplitudes greater than zero and negative for signal amplitudes less than zero; means for operating on said seventh signal to form a second square wave that is positive for signal amplitudes greater than zero and negative for signal amplitudes less than zero; means for detecting the phase difference between said first and second square waves to provide a resulting signal of a polarity indicative of the phase relationship of said fifth signal to said seventh signal; and output means responsive to said fifth signal and said resulting signal to provide, in cooperation with said rectifying and filtering means, said direct current signal representing the angular velocity and direction of rotation of said rotor.

Claim 11

Apparatus as defined in claim 8 including means for compensating said seventh signal for a steady state component of phase shift in said resolver to produce said seventh signal according to the function (Qt+ (t)+ lambda ), where lambda is the varying component of the phase shift by changing resolver parameters.

Claim 12

Apparatus as defined in claim 9 wherein said output means comprises: means for filtering out the effects of varying phase shift lambda on said resulting signal to provide a filtered resulting signal; means connected to the output of said filtering means for producing a sign signal of zero volts when the phase difference between said fifth signal and said compensated signal is zero and said filtered resulting signal is zero volts, a sign signal of a predetermined amplitude and given polarity when said phase difference is of a given polarity and said filtered resulting signal is of a given voltage polarity, and a sign signal of said predetermined amplitude and a voltage polarity opposite said given voltage polarity when said phase difference is of a polarity opposite said given polarity and said filtered resulting signal is of a voltage polarity opposite said given voltage polarity; means for multiplying said fifth signal by said sign signal to provide an eighth signal that eliminates ambiguity in said fifth signal caused by the direction of rotation of said rotor angle; means for rectifying said eighth signal to obtain a ninth signal representing the absoluTe value of said eighth signal; means for multiplying said ninth signal by said sign signal to obtain an output product signal; and means for filtering said output product signal.