Abstract: A dual phase resolver to digital converter having two separate channels for generating rotor position data. The first channel generates an indication of rotor position based on a sinewave type reference signal applied to a first stator winding and the rotor signal while the second channel provides an indication of rotor position based on a cosinewave type reference signal applied to the second stator winding and the rotor signal. Logic circuitry associated with the data channels provide separate fault data indicative of when position data may be subject to error. The data from the two channels are selectively combined in the output of the converter. Data from one channel is used when the other channel is subject to fault. An average of the data is used when both channels are operating properly in order to provide greater accuracy.

Abstract: A simplified magnetic resolver for measurement of rotary or linear position which comprises a permanent magnet rotor and two pairs of sensing coils. The resolver produces sine and cosine outputs compatible with known resolver-to-digital converters.

Abstract: A method of correcting quadrature signal errors comprises the steps for generating an error function signal E by summing the squares of the quadrature signals and subtracting a constant K therefrom, saving the value of the error function E at .theta. equals approximately 0, .pi./2, .pi., and 3.pi./2, using the saved values of the error function to generate signals indicative of the quadrature errors, and generating corrected quadrature signals by processing the quadrature signals to eliminate the errors.

Abstract: Position indicating apparatus that allows position detection with windings provided on only one of two members and an output signal in which the position of one of the members relative to the other member is directly encoded in the phase of the output signal. A first member has a plurality of spaced ferromagnetic protuberances. A second member, movable with respect to the first member, contains at least first, second and third poles located in proximity to the protuberances and spans 360 spatial degrees. Each pole contains a winding with one terminal of each winding connected to a common point. The windings are driven at a fundamental carrier frequency with individual signals of equal amplitude but different temporal phases that span 360 temporal degrees. Circuit means detect the phase of the resulting carrier signal at the common point, which phase is linearly representative of position.

Abstract: An ac encoded signal to digital converter suitable for converting ac synchro or resolver signals to a corresponding digital angle value. A synchronous demodulator including a high pass input filter and low pass output filter utilizes the associated reference excitation signal to convert the individual ac encoded signals to corresponding dc values. The absolute value of the dc values are proportional to the amplitude of each of the respective ac encoded signals, but the dc value is negative if the ac encoded signal is 180.degree. out of phase with the reference excitation signal. These dc values are subsequently digitized and digitally processed based on their trigonometric relationship to extract the encoded angular position value.

Abstract: An absolute position detector for detecting an absolute position of a rotating shaft (1) includes a rotatable shaft and first gearing for operatively coupling the rotating shaft to the rotatable shaft (3a). Resolvers are provided, each having a stator and a rotor. The stator includes pole teeth made of a magnetic material and arranged along an outer circumference of the rotating shaft at a distance from the rotating shaft. The rotor includes a rotor made of a magnetic material respectively associated with pole teeth and located between the rotating shaft and pole teeth. Second gearing operatively couples the rotor of the resolvers to the rotatable shaft. Upon a rotation of the rotating shaft, the first gearing causes the rotatable shaft to rotate, and upon a rotation of the rotatable shaft, the second gearing (14 and 15) causes the rotor of each of the resolvers, at incrementally different gear ratios, to vary reluctance of a magnetic circuit formed by the pole teeth of an associated stator portion.

Abstract: A motor feedback control system which in addition to a quantized digital position feedback value, uses a feedback signal which represents the error between the actual motor position and the quantized digital position. The error function is combined with the quantized digital position value to produce a digital position value with greater resolution. The combined value is differentiated to produce a velocity value for velocity feedback control of the motor.

Abstract: A synchro-to-digital converter circuit is disclosed which includes memories that store digitized representations of the waveforms produced by the resolver. By matching these digitized waveforms to the specific resolver with which the circuit is to be employed, errors produced by the resolver are compensated.Two embodiments of the synchro-to-converter circuit are disclosed as well as a circuit for creating and storing the matched waveforms.

Abstract: A method is provided for detecting a position, comprising the steps of: producing two-phase sinusoidal wave signals having a 90.degree.-spatial phase difference therebetween upon movement of a moving object; detecting the current voltage V.sub.a and V.sub.b of the two-phase sinusoidal wave signals and calculating a value of .alpha. making a value of V zero, given by V=V.sub.a .multidot.cos.alpha.-V.sub.b .multidot.sin.alpha.; determining the value of .alpha. so that polarities of sin.alpha. and cos.alpha. for the calculated .alpha. coincide with those of V.sub.a and V.sub.b, respectively; and detecting a moving position of the moving object by using the value of .alpha. determined in the preceding step as absolute position data within 1 cycle of the 2-phase signals. According to the above method for detecting a position, the absolute position of a moving object can be detected with a high resolution.

Abstract: An apparatus for generating phase modulated angular positional signals in digital form. A phase tracking loop receives a phase modulated signal from the rotor of a resolver whose stator windings are excited in quadrature. The phase output of the resolver is proportional to the angular displacement of the rotor. Signals for exciting the stator windings of the resolver are applied in phase quadrature to a phase detector to develop an analog error signal when combined with the rotor output signal. The analog phase error signal provides an output indicative of the angular displacement of the rotor. The error signal is applied to a voltage controlled oscillator, converted to digital form, and combined with the excitation signals in a closed loop to force the error signal to a null, whereupon the indicated digital output angle is in coincidence with the angular displacement of the rotor shaft.

Abstract: Method and apparatus for indicating the position of a core member of a linear variable differential transformer having a primary coil and a secondary coil. A square pulse is applied to the primary coil. The secondary coil is sampled a predetermined time after applying the square pulse. In one embodiment a periodic square wave signal is applied to the primary and the secondary is periodically sampled.

Abstract: The method of forming a compact resolver/encoder assembly which is impervious to moisture, comprises several steps. First a number of electronic components of the resolver/encoder are mounted on a flexible printed circuit board. The circuit board is then folded into a generally cylindrical envelope and placed in a generally cylindrical container having a closed bottom end and an upper open end. The folded circuit board tens to unfold against the inner surface of the cylindrical wall of said container. Then a form made of stiff but flexible paperboard is inserted within the cylindrical envelope and tends to unfold to take on a tear drop cross section. Next a heat insulating potting compound is inserted into the generally annular space in the container between the form and the cylindrical wall of the container where the folded, printed circuit board is located.