Position measuring transformer having multiple independent sections for reduction of measurement errors

Claim 2

A position measuring apparatus including first and second relatively movable members, one of said members including a first winding of periodically spaced conductors which define a reference cycle, the other of said members including at least one winding group having at least two spaced windings reactively coupled to said first winding for defining a space angle as a function of the pOsition of said spaced windings relative to said first winding, said apparatus including at least one source of electrical signals defining an electrical angle to form at least one measurement signal and further including means for nulling said measurement signal by rendering the space angle equal to the electrical angle, the improvement comprising, a plurality of independently operable winding groups on said other of said members, each group including first and second spaced winding sections reactively coupled to said first winding, and each group spaced relative to said first winding to define independently the same said space angle, means for supplying electrical signals defining an electrical angle independently for each of said winding groups to form a separate measurement signal for each of said winding groups, means for independently nulling each of said separate measurement signals for each of said winding groups.

Claim 3

The apparatus of claim 1 wherein said first winding sections are positioned at periodic first locations and said second winding sections are positioned at periodic second locations in space-quadrature with respect to said reference cycle.

Claim 4

The apparatus of claim 1 further including, means responsive to said measurement signals for forming, for each of said winding groups, a digital representation of the relative space position of said members as measured by each of said winding groups.

Claim 5

The apparatus of claim 3 further including, means for recording and averaging said digital representations to form a resultant digital representation of the relative space position of said members.

Claim 6

The apparatus of claim 4 wherein said members are rotary in form and wherein there are four winding groups arranged to form four quadrants, respectively, on said other member.

Claim 7

The apparatus of claim 3 further including, switching means for sequentially energizing said winding groups so as to sequentially produce said measurement signals and said digital representations.

Claim 8

The apparatus of claim 3 wherein said members are relatively rotable, wherein each winding group has an associated winding group located 180 degrees about a first axis, and wherein said first winding is distributed in a rotary pattern on said one member about a second axis where the second axis may exhibit some eccentricity with respect to said first axis, said apparatus further comprising, means for measuring said eccentricity between said first and second axes includes means for subtracting the digital representation for each winding group from the digital representation for the 180 degree associated winding group.

Claim 9

The apparatus of claim 7 wherein the number of said winding groups is four for obtaining two components, each along an axis orthogonal to the other, of the eccentricity between said first and second axes.

Claim 10

The apparatus of claim 2 wherein said winding groups are symmetrically disposed in a rotary pattern on a stator and wherein said first winding is disposed in a rotary pattern on a rotor forming a position measuring transformer wherein the rotor forms a space angle X with respect to the stator, said apparatus further comprising, means for independently energizing said first winding sections in each winding group with an electrical signal proportional to (A)sin(Y) and said second winding sections in each winding group with an electrical signal proportional to (A)cos(Y) so as to induce a resultant signal in said first winding proportional to (A)sin(X-Y), means for changing one of the values X or Y while holding the other value fixed to reduce said resultant signal to a null and thereby to indicate that the changed value equals the fixed value.

Claim 11

The apparatus of claim 9 wherein, said means for changing comprises a digital to analog converter including a digital counter registering said value Y and means for changing the count in said digital counter to change the value of Y.

Claim 12

The apparatus of claim 10 further including a digital display connected to and operative to display the contents of said digital counter.

Claim 13

The apparatus of claim 2 wherein said winding groups are symmetrically disposed in a rotary pattern on a stator and wherein said first winding is disposed in a rotary pattern on a rotor forming a position measuring transformer wherein the rotor forms a space angle X with respect to the stator, said apparatus further comprising, means for energizing said first winding with a constant amplitude AC signal whereby electrical signals of the form (A)sin(X) and (A)cos(X) are induced in each winding group, computer network means responsive to said signals of the form (A)sin(X) and (A)cos(X) to produce a resultant signal proportional to (A)sin(X-Y), and meanS for changing one of the values X or Y while holding the other value fixed to reduce said resultant signal to a null and to thereby indicate that the changed value equals the fixed value.

Claim 14

The apparatus of Claim 12 wherein, said means for changing includes a digital counter for registering the value Y and wherein said digital counter and said computer network means are responsive to said resultant signal.

Claim 15

A position measuring apparatus including, a transformer having a rotor relatively movable with respect to a stator for generating measurement signals as a function of electrical input signals functionally related to an electrical angle Y and as a function of the relative space position of said rotor and stator as measured by a space angle X, said rotor including a continuous winding having active conductor bars defining a pole cycle, said stator including sine and cosine windings, a digital-to-analog converter for energizing said sine winding with an electrical signal functionally related to cos(Y) to produce a signal proportional to sin(X)cos(Y) and for energizing said cosine winding with an electrical signal functionally related to sin(Y) to produce a signal proportional to cos(X)sin(Y) thereby forming a resultant signal in said continuous winding proportional to sin(X-Y) for controlling said digital-to-analog converter, a digital counter for storing a digital representation of the electrical angle Y, a counter control connected to receive said resultant signal and for causing said digital counter to change its contents until said resultant signal is a null, a digital computer connected to said digital counter for recording the contents of said digital counter each time a null condition is detected, the improvement comprising, a plurality of independently operable winding groups on said stator, each group inductively coupled to said continuous winding, each group including a plurality of winding sections of sine and cosine significance in space-quadrature of the pole cycle of the continuous winding, each alternate winding section of one significance for each group interconnected to form a sine winding for inducing in said continuous winding a signal related to sin(X), each other alternate winding section of the other significance for each group interconnected to form a cosine winding for inducing in said continuous winding a signal related to cos(X), automatic switching means for sequentially energizing each of said winding groups with the signals from said digital-to-analog converter so as to form said digital representation of Y for each group and for recording each digital representation of Y in said computer, and means in said computer for averaging said recorded digital representations of Y in order to form a resultant measure of the space angle X.

Claim 16

A position measuring apparatus including, a transformer having a rotor relatively movable with respect to a stator for generating measurement signals as a function of electrical input signals functionally related to an electrical angle Y and as a function of the relative space position of said rotor and stator as measured by a space angle X, said rotor including a continuous winding having active conductor bars defining a pole cycle, said stator including sine and cosine windings, a digital-to-analog converter for energizing said sine winding with an electrical signal functionally related to cos(Y) to produce a signal proportional to sin(X)cos(Y) and for energizing said cosine winding with an electrical signal functionally related to sin(Y) to produce a signal proportional to cos(X)sin(Y) thereby forming a resultant signal in said continuous winding proportional to sin(X-Y) for controlling said digital-to-analog converter, a digital counter for storing a digital representation of the electrical angle Y, a counter control connected to receive said resultant signal and for causing said digital counter to change its contents until said resultant signal is a null, a digital computer connected to said digital counter for recording the contents of said digital counter each time a null condition is detected, the improvement comprising, a plurality of independently operable winding groups on said stator, each group inductively coupled to said continuous winding, each group including a plurality of winding sections of sine and cosine significance in space-quadrature of the pole cycle of the continuous winding, each alternate winding section of one significance for each group interconnected to form a sine winding for inducing in said continuous winding a signal related to sin(X), each other alternate winding section of the other significance for each group interconnected to form a cosine winding for inducing in said continuous winding a signal related to cos(X), automatic switching means for sequentially energizing each of said winding groups with the signals from said digital-to-analog converter so as to form said digital representation of Y for each group and for recording each digital representation of Y in said computer, and means in said computer for averaging said recorded digital representations of Y in order to form a resultant measure of the space angle X.

Claim 19

The method of claim 15 further including the steps of, averaging said recorded digital representations to form a resultant value as a measure of the space angle X.

Claim 20

The method of claim 15 further including the steps of, subtracting said recorded digital representations for winding groups having 180* position relationship to form a component measure of the eccentricity of the stator windings with respect to the rotor winding.