# US 10,480,961 B2 · Hybrid encoder system for position determination

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- Number: US 10,480,961 B2
- Document ID: US10480961B2
- Status: Granted
- Kind: B2
- Application number: 15/911,808
- Filed: 2018-03-05
- Published: 2018-08-02
- Granted: 2019-11-19
- Earliest claimed: 2017-01-31
- Assignees: Rockwell Automation Technologies, Inc.
- Applicants: Rockwell Automation Technologies, Inc.
- Inventors: Xikai Sun; Peter M. Smit; Mark R. Cooper; Oliver C. Haya; Aderiano M. da Silva
- Web page: https://patentgrep.com/patent/US10480961B2

## CPC

- G01D 5/2046: {by a movable ferromagnetic element, e.g. a core}
- G01D 5/145: {influenced by the relative movement between the Hall device and magnetic fields (see G01R33/06)}
- G01D 5/2073: {by movement of a single coil with respect to two or more coils}
- G01D 2205/77: Specific profiles
- G01D 2205/771: Toothed profiles
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR

## Abstract

A linear and curvilinear encoder is provided in which absolute mechanical position and high resolution position determination can be obtained using a cart having a mover with “hybrid” teeth, configured in a curvilinear profile or shape, moving along a curvilinear track with a stator having teeth. The absolute mechanical position and high resolution position determination can be detected on the track by applying an excitation signal to a coil surrounding particular teeth of the stator to produce an electromagnetic (EM) field which can be influenced by the profile or shape of the teeth of the mover. A resulting pick-up signal can then be detected in a pick-up coil surrounding particular teeth of the stator with different harmonics in the pick-up signal corresponding to harmonics of the profile or shape of the teeth.

## Claims

### Claim 1

An industrial control system for moving objects, comprising:
a track having curved and linear sections;
a stator disposed along the track, the stator having a plurality of teeth;
a cart for moving objects along the track, the cart having a mover portion having a plurality of teeth, wherein the teeth of the mover portion are arranged to face the teeth of the stator across a gap, and wherein the teeth of the mover portion have a curvilinear profile with first and second harmonics;
an excitation coil surrounding teeth of the stator, wherein an excitation signal provided to the excitation coil is operable to produce an electromagnetic (EM) field; and
a pick-up coil surrounding teeth of the stator, wherein presence of the cart in the EM field induces a pick-up signal in the pick-up coil with first and second harmonics caused by the first and second harmonics of the curvilinear profile of the teeth of the mover portion in the EM field for determining a fine position of the mover portion with respect to the stator from the first harmonic and a coarse position of the mover portion with respect to the stator from the second harmonic.

### Claim 2 (depends on 1)

The system of claim 1, wherein the first and second harmonics of the curvilinear profile of the teeth of the mover portion provide magnetic pole pairs in the EM field.

### Claim 3 (depends on 2)

The system of claim 2, wherein the first harmonic of the curvilinear profile of the teeth of the mover portion provides at least five magnetic pole pairs for inducing the second harmonic in the pick-up signal being at least a fifth order harmonic and the second harmonic of the curvilinear profile of the teeth of the mover portion provides one magnetic pole pair for inducing the first harmonic in the pick-up signal being a first order harmonic.

### Claim 4 (depends on 1)

The system of claim 1, wherein the coarse position provides an absolute mechanical position of the mover portion with respect to the stator in a section of the track with lower resolution and the fine position provides a non-absolute mechanical position of the mover portion with respect to the stator in the section of the track with higher resolution.

### Claim 5 (depends on 1)

The system of claim 1, further comprising a controller receiving the pick-up signal, wherein the controller executes a fast Fourier transform (FFT) of the pick-up signal to derive the first and second harmonics.

### Claim 6 (depends on 1)

The system of claim 1, wherein the teeth of the stator have a rectangular profile.

### Claim 7 (depends on 1)

The system of claim 1, wherein the pick-up coil is a first pick-up coil and the pick-up signal is a first pick-up signal, and further comprising a second pick-up coil surrounding teeth of the stator, wherein the EM field induces a second pick-up signal in the second pick-up coil with the first and second harmonics for determining the coarse and fine positions.

### Claim 8 (depends on 7)

The system of claim 7, wherein the first and second pick-up signals provide sine and cosine measurements, respectively.

### Claim 9 (depends on 1)

The system of claim 1, further comprising a plurality of controllers, wherein each section of the track provides an output to a controller for determining the coarse and fine positions and a direction of the mover portion with respect to the stator in a section of the track.

### Claim 10 (depends on 1)

The system of claim 1, wherein the gap is defined by a trigonometric function.

### Claim 11

A method for moving objects in an industrial control system, comprising:
providing a track having curved and linear sections;
providing a stator along the track, the stator having a plurality of teeth;
providing a cart for moving objects along the track, the cart having a mover portion having a plurality of teeth, wherein the teeth of the mover portion are arranged to face the teeth of the stator across a gap, and wherein the teeth of the mover portion have a curvilinear profile with first and second harmonics;
providing an excitation signal to an excitation coil surrounding teeth of the stator to produce an electromagnetic (EM) field;
detecting a pick-up signal in a pick-up coil surrounding teeth of the stator, wherein presence of the cart in the EM field induces first and second harmonics in the pick-up signal caused by the first and second harmonics of the curvilinear profile of the teeth of the mover portion in the EM field; and
determining a fine position of the mover portion with respect to the stator from the first harmonic and a coarse position of the mover portion with respect to the stator from the second harmonic.

### Claim 12 (depends on 11)

The method of claim 11, wherein the first and second harmonics of the curvilinear profile of the teeth of the mover portion provide magnetic pole pairs in the EM field.

### Claim 13 (depends on 12)

The method of claim 12, wherein the first harmonic of the curvilinear profile of the teeth of the mover portion provides at least five magnetic pole pairs for inducing the second harmonic in the pick-up signal being at least a fifth order harmonic and the second harmonic of the curvilinear profile of the teeth of the mover portion provides one magnetic pole pair for inducing the first harmonic in the pick-up signal being a first order harmonic.

### Claim 14 (depends on 11)

The method of claim 11, wherein the coarse position provides an absolute mechanical position of the mover portion with respect to the stator in a section of the track with lower resolution and the fine position provides a non-absolute mechanical position of the mover portion with respect to the stator in the section of the track with higher resolution.

### Claim 15 (depends on 11)

The method of claim 11, further comprising executing a fast Fourier transform (FFT) of the pick-up signal to derive the first and second harmonics.

### Claim 16 (depends on 11)

The method of claim 11, wherein the teeth of the stator have a rectangular profile.

### Claim 17 (depends on 11)

The method of claim 11, wherein the pick-up coil is a first pick-up coil and the pick-up signal is a first pick-up signal, and further comprising detecting a second pick-up signal in a second pick-up coil surrounding teeth of the stator, wherein presence of the cart in the EM field induces the second pick-up signal in the second pick-up coil with the first and second harmonics for determining the coarse and fine positions.

### Claim 18 (depends on 17)

The method of claim 17, wherein the first and second pick-up signals provide sine and cosine measurements, respectively.

### Claim 19 (depends on 11)

The method of claim 11, further comprising determining the coarse and fine positions and a direction of the mover portion with respect to the stator in a section of the track.

### Claim 20 (depends on 11)

The method of claim 11, wherein the gap is defined by a trigonometric function.