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US 4,429,267 AGranted
Digital positioning systems having high accuracy
AssigneeManhattan Engineering Company, Inc.
InventorJohn R. Veale
Life of this patent
Estimating the term…
Abstract
A digital positioning system having high accuracy is disclosed, which employs an incremental position optical encoder as the position transducer. In response to the output signal from the encoder, the system provides coarse and fine position signals which are combined to form a composite digital signal representing the absolute position of a moveable control member. The composite position signal has a resolution of greater than one part in one million. Trigonometric conversion techniques are used to derive high resolution incremental position information from the encoder output signals.
Claims18
A digital positioning system for precisely controlling the position of a dynamically moveable member, comprising:
- position sensor means for sensing an incremental position of the member, and for providing first and second sensor signals in the form of first and second periodic trigonometric functions, respectively, each representative of the incremental position of the member within a fixed interval of distance, and providing a third sensor signal representative of a reference position of the member;
- means responsive to the three sensor signals for providing a coarse position signal including means for counting the number of cycles of the first sensor signal;
- means responsive to the first and second sensor signals for providing a fine position signal including means for combining the first and second sensor signals to form a third trigonometric function, and means for converting the third trigonometric function to an angle representative of the incremental position of the member within the fixed interval of distance;
- means for combining the coarse and fine digital position signals to form a composite position signal representing the absolute position of the member;
- and
- means for providing a corrective signal to correct the position of the member based on the composite digital position signal.
3 more elements
Apparatus for providing a high accuracy absolute position signal from an incremental position sensor, comprising:
- position sensor means for sensing an incremental position of a dynamically moveable member, the sensor providing first and second signals in the form of first and second periodic trigonometric functions, respectively, each representative of the incremental position of the member within a fixed interval of distance, and providing a third sensor signal representative of a reference position of the member;
- means responsive to the three sensor signals for providing a coarse position signal including means for counting the number of cycles of the first sensor signal;
- means responsive to the first and second sensor signals for providing a fine position signal including means for combining the first and second sensor signals to form a third trigonometric function, and means for converting the third trigonometric function to an angle representative of the incremental position of the member within the fixed interval of distance;
- and
- means for combining the coarse and fine digital position signals to form a composite position signal representing the absolute position of the member.
2 more elements
A method of precisely controlling the position of a dynamically moveable member, comprising the steps of:
- providing first and second sensor signals in the form of first and second periodic trigonometric functions, respectively, each representative of the incremental position of the member within a fixed interval of distance;
- providing a third sensor signal representative of a reference position of the member;
- counting the number of cycles of the first sensor signal in response to the three sensor signals;
- combining the counted number of cycles of the first sensor signal with a quantity representing the fixed interval of distance to form a coarse position signal;
- combining the first and second sensor signals to form a third trigonometric function;
- converting the third trigonometric function to an angle representative of the incremental position of the member within the fixed interval of distance;
- combining the angle with a quantity representing the fixed interval of distance to form a fine position signal;
- combining the coarse and fine digital position signals to form a composite position signal representing the absolute position of the member;
- and
- controlling the position of the member as a function of the difference between the composite position signal and a command position signal.
7 more elements
A method of precisely controlling the position of a dynamically moveable member, comprising the steps of:
- providing first and second sensor signals in the form of the sine and cosine, respectively, of an angle representative of the incremental position of the member within a fixed interval of distance;
- providing a third sensor signal representative of a reference position of the member;
- counting the number of cycles of the first sensor signal in response to the three sensor signals;
- combining the counted number of cycles of the first sensor signal with a quantity representing the fixed interval of distance to form a coarse position signal;
- combining the first and second signals to form the tangent of the angle;
- converting the tangent of the angle to the angle representative of the incremental position of the member within the fixed interval of distance;
- combining the angle with a quantity representing the fixed interval of distance to form a fine position signal;
- combining the coarse and fine digital position signals to form a composite position signal representing the absolute position of the member;
- and
- controlling the position of the member as a function of the difference between the composite position signal and a command position signal.
7 more elements
Dependencies are inferred from the claim text.