Rotation parameter detection method, encoder, laser radar and unmanned aerial vehicle

Patent metadata

Field	Value
Publication number	US-10859409-B2
Application number	US-202016742171-A
Country	US
Kind code	B2
Filing date	Jan 14, 2020
Priority date	Dec 12, 2017
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

An encoder includes a code disc and a processor communicatively coupled with the code disc. The code disc is configured to rotate along with a rotating object and includes a plurality of fan teeth extending radially. Each of the fan teeth includes a first line segment edge, a second line segment edge, and an arc edge along a circumference of the code disc and connecting the first line segment edge and the second line segment edge. The first line segment edges of the fan teeth are arranged at the code disc with equal intervals. A length of the arc edge of one of the fan teeth is different from lengths of the arc edges of other ones of the fan teeth, and the lengths of the arc edges of the other ones of the fan teeth equal each other. The processor is configured to detect a rotation of the code disc to obtain a detection signal, and obtain a rotation parameter of the rotating object based on the detection signal. The rotation parameter includes at least one of a rotation direction, a rotation speed, or a mechanical zero position.

First claim

What is claimed is:

1. An encoder comprising:
a code disc configured to rotate along with a rotating object and including a plurality of fan teeth extending radially, wherein:
each of the fan teeth includes a first line segment edge, a second line segment edge, and an arc edge along a circumference of the code disc and connecting the first line segment edge and the second line segment edge;
the first line segment edges of the fan teeth are arranged at the code disc with equal intervals; and
a length of the arc edge of one of the fan teeth is different from lengths of the arc edges of other ones of the fan teeth, and the lengths of the arc edges of the other ones of the fan teeth equal each other; and

a processor communicatively coupled with the code disc and configured to:
detect a rotation of the code disc to obtain a detection signal; and
obtain a rotation parameter of the rotating object based on the detection signal, the rotation parameter includes at least one of a rotation direction, a rotation speed, or a mechanical zero position.

2. The encoder of claim 1 , further comprising:
a photo sensor communicatively coupled with the processor and configured to generate the detection signal;
wherein the detection signal includes:
a continuous first signal detected when any of the fan teeth blocks the photo sensor, and
a continuous second signal detected when none of the fan teeth blocks the photo sensor, the first signal being different from the second signal.

3. The encoder of claim 2 , wherein the first signal includes a low-level signal and the second signal includes a high-level signal.

4. The encoder of claim 3 , wherein the detection signal includes a square wave signal.

5. The encoder of claim 1 , wherein the processor is further configured to determine the rotation direction based on at least one of rising edges or falling edges in the detection signal in a rotation period of the rotating object.

6. The encoder of claim 5 , wherein the processor is further configured to determine the rotation direction based on at least one of a time relationship between the rising edges in the detection signal or a time relationship between the falling edges in the detection signal in the rotation period of the rotating object.

7. The encoder of claim 6 , wherein:
for each of the fan teeth, the first line segment edge is disposed in a clockwise direction with respect to the second line segment edge; and
the processor is further configured to determine the rotation direction to be counterclockwise in response to determining that:
the rising edges are equally separated in time in the rotation period, or
the falling edges are not always equally separated in time in the rotation period.

8. The encoder of claim 6 , wherein:
for each of the fan teeth, the first line segment edge is disposed in a clockwise direction with respect to the second line segment edge; and
the processor is further configured to determine the rotation direction to be clockwise in response to determining that:
the falling edges are equally separated in time in the rotation period, or
the rising edges are not always equally separated in time in the rotation period.

9. The encoder of claim 6 , wherein:
for each of the fan teeth, the first line segment edge is disposed in a counterclockwise direction with respect to the second line segment edge; and
the processor is further configured to determine the rotation direction to be clockwise in response to determining that:
the rising edges are equally separated in time in the rotation period, or
the falling edges are not always equally separated in time in the rotation period.

10. The encoder of claim 6 , wherein:
for each of the fan teeth, the first line segment edge is disposed in a counterclockwise direction with respect to the second line segment edge; and
the processor is further configured to determine the rotation direction to be counterclockwise in response to determining that:
the falling edges are equally separated in time in the rotation period, or
the rising edges are not always equally separated in time in the rotation period.

11. The encoder of claim 1 , wherein the processor is further configured to:
obtain a duration of the detection signal in a rotation period of the rotating object; and
determine the rotation speed based on the duration.

12. The encoder of claim 1 , wherein the processor is further configured to determine the rotation speed based on at least one of a time relationship between rising edges in the detection signal or a time relationship between falling edges in the detection signal in a rotation period of the rotating object.

13. The encoder of claim 12 , wherein the processor is further configured to:
obtain time differences, each of the time differences being between two adjacent ones of the rising edges or between two adjacent ones of the falling edges;
obtain an average time difference based on the time differences; and
determine the rotation speed based on the average time difference.

14. The encoder of claim 12 , wherein the processor is further configured to determine the rotation speed based on:
a time difference between any two adjacent ones of the rising edges in response to the rising edges being equally separated in time in the rotation period; or
a time difference between any two adjacent ones of the falling edges in response to the falling edges being equally separated in time in the rotation period.

15. The encoder of claim 1 , wherein the processor is further configured to determine the mechanical zero position based on at least one of rising edges or falling edges in the detection signal in a rotation period of the rotating object.

16. The encoder of claim 15 , wherein the processor is further configured to, in response to the rising edges not always being equally separated in time in the rotation period:
determine a reference rising edge based on a time relationship between the rising edges in the rotation period; and
determine the mechanical zero position based on a time point of the reference rising edge, a time difference between the reference rising edge and the rising edge preceding the reference rising edge being not equal to a time difference between the reference rising edge and the rising edge succeeding the reference rising edge.

17. The encoder of claim 15 , wherein the processor is further configured to, in response to the falling edges are not always equally separated in time in the rotation period:
determine a reference falling edge based on a time relationship between the falling edges in the rotation period; and
determine the mechanical zero position based on a time point of the reference falling edge, a time difference between the reference falling edge and the falling edge preceding the reference falling edge being not equal to a time difference between the reference falling edge and the falling edge succeeding the reference falling edge.

18. The encoder of claim 1 , wherein the rotating object includes an electric motor.

Assignees

• Sz Dji Technology Co Ltd

Inventors

• Liu Wanqi
• Lan Qiu
• Zhou Changxing

Classifications

• G01S7/481

  Constructional features, e.g. arrangements of optical elements · CPC title

• G01P13/02

  Indicating direction only, e.g. by weather vane · CPC title

• G01P3/38

  using photographic means · CPC title

• G01P3/486

  delivered by photo-electric detectors · CPC title

• G01D5/3473 Primary

  Circular or rotary encoders · CPC title