# US 2021/0333399 A1 · Detection method, detection device, and lidar

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- Number: US 2021/0333399 A1
- Document ID: US20210333399A1
- Status: Published application
- Kind: A1
- Application number: 17/371,676
- Filed: 2021-07-09
- Published: 2021-10-28
- Earliest claimed: 2019-01-09
- Assignees: Sz Dji Technology Co., Ltd.
- Applicants: Sz Dji Technology Co., Ltd.
- Inventors: Jin ZHAO; Chenghui LONG; Huai HUANG
- Web page: https://patentgrep.com/patent/US20210333399A1

## CPC

- G01D 5/2457: {Incremental encoders having reference marks}
- G01S 17/87: Combinations of systems using electromagnetic waves other than radio waves
- G01B 5/24: for measuring angles or tapers; for testing the alignment of axes
- G01D 5/34707: {Scales; Discs, e.g. fixation, fabrication, compensation}
- G01D 5/34792: {with only digital scales or both digital and incremental scales}
- G01P 3/486: delivered by photo-electric detectors
- G01P 3/487: delivered by rotating magnets
- G01S 7/4808: {Evaluating distance, position or velocity data}
- G01S 7/4817: {relating to scanning}
- G01S 17/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46)
- 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
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})

## Abstract

A detection method includes obtaining first count data and second count data during rotation of an encoder disc mounted at and configured to rotate together with a rotation object and determining a rotation parameter of the rotation object according to the first count data and the second count data. The encoder disc includes N detection target portions arranged along a circumferential direction of the encoder disc. The N detection target portions include N−K first detection target portions and K second detection target portions. Along the circumferential direction of the encoder disc, a width of one of the N−K first detection target portions is different from a width of one of the K second detection target portions. The first count data is obtained when one detection target portion of the N detection target portions is detected. The second count data is recorded between two neighboring detection target portions.

## Claims

### Claim 1

A detection method comprising:
obtaining first count data and second count data during rotation of an encoder disc mounted at and configured to rotate together with a rotation object; and
determining a rotation parameter of the rotation object according to the first count data and the second count data, the rotation parameter including a rotation angle and a rotation speed;
wherein:
the encoder disc includes N detection target portions arranged along a circumferential direction of the encoder disc, N being an integer greater than two;
the N detection target portions include N−K first detection target portions and K second detection target portions, K being an integer greater than or equal to 1 and smaller than N;
along the circumferential direction of the encoder disc, a width of one of the N−K first detection target portions is different from a width of one of the K second detection target portions;
the first count data is obtained when one detection target portion of the N detection target portions is detected; and
the second count data is recorded between two neighboring detection target portions of the N detection target portions.

### Claim 2 (depends on 1)

The method of claim 1, wherein:
the first count data includes a count value; and
obtaining the first count data includes:
in response to detecting a zero position of the encoder disc, clearing the count value; and
in response to detecting the one detection target portion, obtaining the count value.

### Claim 3 (depends on 2)

The method of claim 2, wherein the zero position of the encoder disc corresponds to a position of one of the K second detection target portions.

### Claim 4 (depends on 1)

The method of claim 1, wherein:
the second count data includes a count value; and
obtaining the second count data includes:
in response to detecting one of the N−K first detection target portions or one of the K second detection target portions, clearing the count value; and
in response to receiving a trigger signal, obtaining the count value.

### Claim 5 (depends on 4)

The method of claim 4, wherein the trigger signal includes a signal triggered when the rotation object emits light and/or receives light.

### Claim 6 (depends on 1)

The method of claim 1, wherein:
the first count data includes a first count value and the second count data includes a second count value;
determining the rotation parameter of the rotation object according to the first count data and the second count data includes:
determining a rotation angle in a current rotation round of the encoder disc by using the first count value obtained in a last rotation round of the encoder disc and the second count value obtained in the current rotation round of the encoder disc; and
the rotation angle in the current rotation round of the encoder disc is a rotation angle in the current rotation round of the rotation object.

### Claim 7 (depends on 6)

The method of claim 6, wherein:
determining the rotation angle in the current rotation round of the encoder disc by using the first count value obtained in the last rotation round of the encoder disc and the second count value obtained in the current rotation round of the encoder disc includes:
in response to receiving a trigger signal, determining the rotation angle in the current rotation round of the encoder disc by using the first count value obtained in the last rotation round of the encoder disc, the second count value obtained in the current rotation round of the encoder disc, and an accumulation value of the first count value obtained in the last rotation round of the encoder disc, of a last detection target portion in a rotation direction of the encoder disc;

### Claim 8 (depends on 1)

The method of claim 1, wherein:
the first count data includes a first count value and a first count frequency;
the second count data includes a second count value and a second count frequency;
determining the rotation parameter of the rotation object according to the first count data and the second count data includes:
determining a rotation speed of the encoder disc according to the first count frequency and the first count value; and
the rotation speed of the encoder disc is the rotation speed of the rotation object.

### Claim 9 (depends on 8)

The method of claim 8, wherein:
determining the rotation speed of the encoder disc according to the first count frequency and the first count value includes:
determining a time length needed for the encoder disc to rotate for a round according to the first count frequency and the first count value to determine the rotation speed of the encoder disc.

### Claim 10 (depends on 1)

The method of claim 1, wherein:
along the circumferential direction of the encoder disc, the encoder disc is divided into N detection areas;
each of the N detection areas includes one of the detection target portions and an encoder disc portion; and
the detection target portions and the encoder disc portions are arranged alternately.

### Claim 11 (depends on 10)

The method of claim 10, wherein:
the N encoder disc portions include N−K first encoder disc portions and K second encoder disc portions; and
along the circumferential direction of the encoder disc:
the width of the one of the first detection target portions is smaller than the width of the one of the second detection target portions; and
a width of one of the N−K first encoder disc portions is greater than a width of one of the K second encoder disc portions.

### Claim 12 (depends on 11)

The method of claim 11, wherein, along the circumferential direction of the encoder disc:
the width of the one of the first detection target portions is equal to the width of the one of the second encoder disc portions;
the width of the one of the second detection target portions is equal to the width of the one of the first encoder disc portions; and
the width of the one of the second detection target portions is three times the width of the one of the first detection target portions.

### Claim 13 (depends on 1)

The method of claim 1, wherein one of the detection target portions includes a through-hole, a magnetic member, a light transmission member, or a light reflection member.

### Claim 14

A detection device comprising:
an encoder disc configured to be mounted at and rotate together with a rotation object, wherein:
the encoder disc includes N detection target portions arranged along a circumferential direction of the encoder disc, N being an integer greater than 2;
the N detection target portions include N−K first detection target portions and K second detection target portions, K being an integer greater than or equal to 1 and smaller than N;
along the circumferential direction of the encoder disc, a width of one of the N−K first detection target portions is different from a width of one of the K second detection target portions;
a detection member configured to detect the first detection target portions and the second detection target portions; and
a processor configured to in rotation of the encoder disc:
obtain first count data when one detection target portion of the N detection target portions is detected and second count data between two neighboring detection target portions of the N detection target portions; and
determine a rotation parameter of the rotation object according to the first count data and the second count data, the rotation parameter including a rotation angle and a rotation speed.

### Claim 15 (depends on 14)

The device of claim 14, wherein:
the first count data includes a count value; and
the processor is further configured to:
in response to detecting a zero position of the encoder disc, clear the count value; and
in response to detecting the one detection target portion, obtain the count value.

### Claim 16 (depends on 14)

The device of claim 14, wherein:
the second count data includes a count value; and
the processor is further configured to:
in response to detecting one of the N−K first detection target portions or one of the K second detection target portions, clearing the count value; and
in response to receiving a trigger signal, obtaining the count value.

### Claim 17 (depends on 14)

The device of claim 14, wherein:
the first count data includes a first count value and a first count frequency;
the second count data includes a second count value and a second count frequency;
the processor is further configured to:
determine a rotation speed of the encoder disc according to the first count frequency and the first count value; and
the rotation speed of the encoder disc is the rotation speed of the rotation object.

### Claim 18 (depends on 14)

The device of claim 14, wherein:
along the circumferential direction of the encoder disc, the encoder disc is divided into N detection areas;
each of the N detection areas includes one of the detection target portions and an encoder disc portion; and
the detection target portions and the encoder disc portions are arranged alternately.

### Claim 19

A LIDAR comprising:
an optical element;
a driver for driving the optical element to rotate; and
a detection device configured to detect a rotation parameter of the optical element and including:
an encoder disc configured to be mounted at and rotate together with the optical element, wherein:
the encoder disc includes N detection target portions arranged along a circumferential direction of the encoder disc, N being an integer greater than 2;
the N detection target portions includes N−K first detection target portions and K second detection target portions, K being an integer greater than or equal to 1 and smaller than N;
along the circumferential direction of the encoder disc, a width of one of the N−K first detection target portions is different from a width of one of the K second detection target portions;
a detection member configured to detect the first detection target portions and the second detection target portions; and
a processor configured to in rotation of the encoder disc:
obtain first count data when one detection target portion of the N detection target portions is detected and second count data between two neighboring detection target portions of the N detection target portions; and
determine the rotation parameter of the optical element according to the first count data and the second count data, the rotation parameter including a rotation angle and a rotation speed.

### Claim 20 (depends on 19)

The LIDAR of claim 19, wherein the optical element includes a prism or a lens.

### Claim 21 (depends on 20)

The LIDAR of claim 20, wherein:
the prism has different thicknesses along a radial direction; and
the one of the K second detection target portions is aligned to a position where the prism has a minimal or maximal thickness.

### Claim 22 (depends on 19)

The LIDAR of claim 19, wherein:
the optical element is arranged in a lens barrel;
the lens barrel includes a snap piece;
the encoder disc includes a snap slot; and
the snap piece is at least partially snapped in the snap slot to mount the encoder disc at the lens barrel.