Phase-responsive angular tracking device

Claim 3

Apparatus for indicating angular position of the rotor of a resolver having fixed windings, comprising: a bidirectional counter for providing a digital signal representative of a reference angle, means responsive to said digital signal for providing signals representative of the sine and cosine of said reference angle, means fo providing sine and cosine signals at a predetermined excitation frequency independent of a phase parameter corresponding to said angular position, to respective first and second fixed windings of said resolver, means coupled to said rotor for providing a sinusoidal signal having a phase shift representative of the angular position of said rotor, first multiplication means for providing a first analog signal representative of the product of said sine of the reference angle and said phase angle independent sine signal applied to said resolver and a second analog signal representative of the product of said cosine of the reference angle and said phase angle independent cosine signal applied to said revolver, adder means for providing an algebraic difference of said first and second analog signals having a phase shift corresponding to said reference angle and independent of said phase parameter corresponding to said angular position, second multiplication means for providing a third analog signal comprised of the product of said phase shifted signal from said means coupled to said rotor corresponding to the sine of an angular position thereof and said algebraic difference, and representative of a difference of said angular position and said reference angle, and phase-lock loop means for applying a portion of said third analog signal in closed loop fashion to said bidirectional counter so that said digital signal representative of a reference angle is urged to correspondence with a digital representation of said rotor angular position.

Claim 4

Apparatus for indicating angular position of the rotor of a resolver having fixed windings, comprising: a bidirectional counter for providing a digital signal representative of a reference angle, means responsive to said digital signal for providing signals representative of the sine and cosine of said reference angle, means fo providing sine and cosine signals at a predetermined excitation frequency independent of a phase parameter corresponding to said angular position, to respective first and second fixed windings of said resolver, means coupled to said rotor for providing a sinusoidal signal having a phase shift representative of the angular position of said rotor, first multiplication means for providing a first analog signal representative of the product of said sine of the reference angle and said phase angle independent sine signal applied to said resolver and a second analog signal representative of the product of said cosine of the reference angle and said phase angle independent cosine signal applied to said revolver, adder means for providing an algebraic difference of said first and second analog signals having a phase shift corresponding to said reference angle and independent of said phase parameter corresponding to said angular position, second multiplication means for providing a third analog signal comprised of the product of said phase shifted signal from said means coupled to said rotor corresponding to the sine of an angular position thereof and said algebraic difference, and representative of a difference of said angular position and said reference angle, and phase-lock loop means for applying a portion of said third analog signal in closed loop fashion to said bidirectional counter so that said digital signal representative of a reference angle is urged to correspondence with a digital representation of said rotor angular position.

Claim 5

The apparatus as set forth in claim 2, said third analog signal further comprising first and second component signals, said first component signal proportional to an excitation frequency of said sine and cosine signals and said second component signal representative of a difference between said rotor position and said reference angle.

Claim 6

The apparatus as set forth in claim 3, wherein said first component signal is operative at a predetermined frequency greater than said second component signal.

Claim 7

The apparatus as set forth in claim 4, said filter means comprising low-pass filter means for rejecting said first component signal and for transmitting said second component signal.

Claim 8

The apparatus as set forth in claim 5, further comprising voltage controlled oscillator means, responsive to said second component signal, for providing an output frequency proportional to said analog difference signal.

Claim 9

The apparatus as set forth in claim 6, wherein said bidirectional counter is, responsive to said output frequency, for providing an output signal representative thereof, said output signal corresponding to said digital indication.

Claim 10

The apparatus as set forth in claim 7, said first multiplication means further comprising first trigonometric multiplier means, responsive to the sine of said signal corresponding to said digital representation and to said sine signal applied to said transducer for deriving a product thereof.

Claim 11

The apparatus as set forth in claim 8, further comprising second trigonometric multiplier means, responsive to the cosine of said signal corresponding to said digital representation and to said cosine signal applied to said transducer for deriving a product thereof.

Claim 12

The apparatus as set forth in claim 9, wherein said first and second trigonometric multiplier means are in phase quadrature.

Claim 13

The apparatus as set forth in claim 4, further comprising filter means responsive to said third analog signal for providing said second component signal, comprising said portion of said third analog signal, to said phase-lock loop means.

Claim 14

The apparatus as set forth in claim 11, wherein said second multiplication means comprises a phase detector having first and second inputs for providing an output representative of phase differences between signals applied to said inputs.

Claim 15

The apparatus as set forth in claim 12 wherein said rotor signal is generated by a rotary coupler, said coupler having first and second orthogonal elements fixed in space quadrature, coupled respectively to receive sine and cosine excitation signals, and a third element, axially rotatable with respect to said first and second elements, for providing said rotor signal when said third element is angularly displaced with respect to said first or second elements.