US-12625264-B2 - Distance measuring device and distance measuring method

US12625264B2US 12625264 B2US12625264 B2US 12625264B2US-12625264-B2

Abstract

Provided is a distance measuring device and a distance measuring method capable of achieving LiDAR with high accuracy at low cost. In a plurality of division times obtained by dividing a modulation cycle for chirp-modulating frequencies of transmission beams of a plurality of channels, light emission and extinction of a plurality of light sources are controlled in a unique pattern for each light source, an interference beam between a reception beam and a transmission beam is detected, digitized into a reception signal sequence, and subjected to FFT to obtain a frequency spectrum, a beat frequency is specified from comparison of magnitude of peaks, and a distance to a measurement target and a relative speed are measured. The present disclosure can be applied to LiDAR.

Inventors

Haruhiko Terada

Assignees

SONY SEMICONDUCTOR SOLUTIONS CORPORATION

Dates

Publication Date: 20260512
Application Date: 20211124
Priority Date: 20201208

Claims (18)

1 . A distance measuring device, comprising: a plurality of light sources of a plurality of transmission beams; a processor configured to individually control light emission and light extinction of the plurality of light sources of the plurality of transmission beams, wherein each of the plurality of light sources is controlled at a respective frequency of a plurality of frequencies, the light emission and the light extinction of each of the plurality of light sources is in a unique pattern of each of the plurality of light sources of the plurality of transmission beams; a modulation cycle is divided into a plurality of time sections, and the unique pattern is in units of the plurality of time sections; an optical deflector configured to: deflect the plurality of transmission beams, wherein the plurality of transmission beams are deflected at different respective frequencies of the plurality of frequencies, the plurality of transmission beams are deflected at angles based on the plurality of frequencies; and simultaneously project the plurality of transmission beams to a plurality of visual fields; a detection unit configured to detect an interference beam, wherein the interference beam is based on interference of a local oscillation beam with a reception beam, and the reception beam is a reflection of the plurality of transmission beams by a measurement target; and a modulation unit configured to modulate the plurality of frequencies of the plurality of transmission beams based on the modulation cycle.
2 . The distance measuring device according to claim 1 , wherein the plurality of transmission beams at the different respective frequencies is multiplexed into a multiplexed transmission beam, and the optical deflector is further configured to deflect each of the plurality of transmission beams multiplexed in the multiplexed transmission beam at an angle based on the respective frequency of the plurality of frequencies.
3 . The distance measuring device according to claim 2 , wherein the local oscillation beam is a part of the multiplexed transmission beam.
4 . The distance measuring device according to claim 1 , further comprising: a light emission control table in which a code is registered, wherein the unique pattern for each of the plurality of light sources of the plurality of transmission beams is coded in the registered code, and the unique pattern for each of the light sources of the plurality of transmission beams is based on the code registered in the light emission control table.
5 . The distance measuring device according to claim 1 , wherein the light emission is in a number of time sections of the plurality of time sections in the modulation cycle, and a number of light sources of the plurality of transmission beams is based on the number of time sections of the plurality of time sections in the modulation cycle.
6 . The distance measuring device according to claim 1 , wherein the light emission is in a first number of time sections of the plurality of time sections in the modulation cycle, a number of light sources of the plurality of transmission beams is set based on a second number of time sections in the first number of time sections in the modulation cycle, and the second number of time sections indicate time sections for chirp modulation associated with the light emission.
7 . The distance measuring device according to claim 1 , wherein the modulation unit is further configured to modulate the plurality of frequencies of the plurality of transmission beams with same respective modulation bandwidths.
8 . The distance measuring device according to claim 1 , wherein the modulation unit is further configured to modulate the plurality of frequencies of the plurality of transmission beams with different respective modulation bandwidths.
9 . The distance measuring device according to claim 8 , wherein a distance and a relative speed of the measurement target are based on a plurality of frequency spectra, each of the plurality of frequency spectra corresponds to the respective light source of the plurality of light sources of the plurality of transmission beams, a first reception signal sequence corresponds to a time section in which the plurality of light sources of the plurality of transmission beams emits light, a second reception signal sequence is obtained by photoelectric conversion of an output of the detection unit, the plurality of frequency spectra is obtained by extraction of the first reception signal sequence from the second reception signal sequence, perform discrete Fourier transform on the first reception signal sequence, and the modulation unit is further configured to modulate the plurality of frequencies of the plurality of transmission beams with the different respective modulation bandwidths to be equal to or higher than a frequency resolution in the discrete Fourier transform.
10 . The distance measuring device according to claim 1 , wherein a distance and a relative speed of the measurement target are based on a plurality of frequency spectra respectively corresponding to the plurality of light sources of the plurality of transmission beams, and the plurality of frequency spectra is based on an output of the detection unit.
11 . The distance measuring device according to claim 1 , wherein a distance and a relative speed of the measurement target are specified based on a beat frequency specified from a plurality of frequency spectra respectively corresponding to the plurality of light sources of the plurality of transmission beams, and the plurality of frequency spectra is based on an obtained from the output of the detection unit.
12 . The distance measuring device according to claim 11 , wherein the beat frequency is based on a comparison of magnitudes of peaks of the plurality of frequency spectra respectively corresponding to the plurality of light sources of the plurality of transmission beams.
13 . The distance measuring device according to claim 10 , wherein each of the plurality of frequency spectra corresponds to the respective light source of the plurality of light sources of the plurality of transmission beams, a first reception signal sequence corresponds to a time section in which the plurality of light sources of the plurality of transmission beams emits light, a second reception signal sequence is obtained by photoelectric conversion of the output of the detection unit, the plurality of frequency spectra is obtained by extraction of the first reception signal sequence from the second reception signal sequence, and perform discrete Fourier transform on the first reception signal sequence.
14 . The distance measuring device according to claim 1 , wherein the optical deflector is an optical phased array (OPA).
15 . The distance measuring device according to claim 1 , wherein the optical deflector includes a prism and a rotary mirror.
16 . The distance measuring device according to claim 1 , wherein the distance measuring device is one of coherent light detection and ranging or laser imaging detection and ranging.
17 . A distance measuring method, comprising: in a distance measuring device: individually controlling, by a processor, light emission and light extinction of a plurality of light sources a plurality of transmission beams, wherein each of the plurality of light sources is controlled at a respective frequency of a plurality of frequencies, the light emission and the light extinction of each of the plurality of light sources is in a unique pattern of each of the plurality of light sources of the plurality of transmission beams, a modulation cycle is divided into a plurality of time sections, and the unique pattern is in units of the plurality of time sections; deflecting, by an optical deflector, the plurality of transmission beams, wherein the plurality of transmission beams are deflected at different respective frequencies of the plurality of frequencies, the plurality of transmission beams are deflected at angles based on the plurality of frequencies; and simultaneously projecting, by the optical deflector, the plurality of transmission beams to a plurality of visual fields; detecting, by a detection unit, an interference beam, wherein the interference beam is based on interference of a local oscillation beam with a reception beam, and the reception beam is a reflection of the plurality of transmission beams by a measurement target; and modulating, by a modulation unit, the plurality of frequencies of the plurality of transmission beams based on the modulation cycle.
18 . A non-transitory computer-readable medium having stored thereon, computer-executable instructions which, when executed by a computer, cause the computer to execute operations, the operations comprising: individually controlling light emission and light extinction of a plurality of light sources of a plurality of transmission beams, wherein each of the plurality of light sources is controlled at a respective frequency of a plurality of frequencies, the light emission and the light extinction of each of the plurality of light sources is in a unique pattern of each of the plurality of light sources of the plurality of transmission beams, a modulation cycle is divided into a plurality of time sections, and the unique pattern is in units of the plurality of time sections; deflecting the plurality of transmission beams, wherein the plurality of transmission beams are deflected at different respective frequencies of the plurality of frequencies, the plurality of transmission beams are deflected at angles based on the plurality of frequencies; and simultaneously projecting the plurality of transmission beams to a plurality of visual fields; detecting an interference beam, wherein the interference beam is based on interference of a local oscillation beam with a reception beam, and the reception beam is a reflection of the plurality of transmission beams, by a measurement target; and modulating the plurality of frequencies of the plurality of transmission beams based on the modulation cycle.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a U.S. National Phase of International Patent Application No. PCT/JP2021/042881 filed on Nov. 24, 2021, which claims priority benefit of Japanese Patent Application No. JP 2020-203412 filed in the Japan Patent Office on Dec. 8, 2020. Each of the above-referenced applications is hereby incorporated herein by reference in its entirety. TECHNICAL FIELD The present disclosure relates to a distance measuring device, a distance measuring method, and a program, and more particularly relates to a distance measuring device, a distance measuring method, and a program capable of achieving highly accurate distance measurement at low cost. BACKGROUND ART Distance measuring devices called light detection and ranging, laser imaging detection and ranging (LiDAR) have been widely used. LiDAR is a distance measuring device that implements distance measurement to an object by irradiating the object with a laser beam as a distance measuring beam, and measuring a round-trip time obtained from an irradiation timing and a beam reception timing of a reflected beam. As a technique for improving resistance to external light in distance measurement performance of LiDAR, a technology has been proposed in which chirp modulation is applied to a laser beam of multiple channels including a plurality of wavelengths having different wavelengths and the laser beam is projected as a transmission beam, a reflected beam from an object is received, and distance measurement is implemented on the basis of a beat frequency that is a difference frequency between the transmission beam and a reference beam having a frequency slightly different from that of the transmission beam (see Patent Document 1). CITATION LIST Patent Document Patent Document 1: US 2020/0142065 A SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, in the technique described in Patent Document 1, since the multi-channel transmission beam and the reference beam are configured as individual light sources, the cost of the light sources increases. Furthermore, since the frequency difference between the distance measuring beam and the reference beam having a slightly different frequency affects distance measurement accuracy, the configuration for controlling the frequency difference with high accuracy becomes complicated, and the cost increases. Moreover, the configuration of a light receiving unit has a high cutoff frequency, and high cost is necessary to achieve high accuracy. The present disclosure has been made in view of such circumstances, and particularly to achieve highly accurate ranging at low cost. Solutions to Problems A distance measuring device and a program according to one aspect of the present disclosure are a distance measuring device including a light source of a plurality of transmission beams, a light emission control unit that individually controls light emission and extinction of the light source of the plurality of transmission beams, an optical deflection unit that deflects the transmission beams at angles depending on the frequencies, and a detection unit that detects an interference beam generated by interference with a reception beam received by reflection of the transmission beams by a measurement target, and a program. A distance measuring method according to one aspect of the present disclosure is a distance measuring method of a distance measuring device including a light source of a plurality of transmission beams, a light emission control unit that individually controls light emission and extinction of the light source of the plurality of transmission beams, an optical deflection unit that deflects the transmission beams at angles depending on the frequencies, and a detection unit that detects an interference beam generated by interference with a reception beam received by reflection of the transmission beams by a measurement target, in which the distance measuring method includes, by the light emission control unit, individually controlling light emission and extinction of the light source of the plurality of transmission beams, by the optical deflection unit, deflecting the transmission beams at angles depending on the frequencies, and by the detection unit, detecting an interference beam generated by interference with a reception beam received by reflection of the transmission beams by a measurement target. In one aspect of the present disclosure, light emission and extinction of the light source of the plurality of transmission beams are individually controlled, the transmission beams are deflected at angles depending on the frequencies, and an interference beam generated by interference with a reception beam received by reflection of the transmission beams by a measurement target is detected. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram describing a configuration example of a distance measuring device for describing an overview of a coherent LiDAR. FIG. 2 is a di