US-12618953-B2 - Lidar control device, lidar control method, and lidar device

US12618953B2US 12618953 B2US12618953 B2US 12618953B2US-12618953-B2

Abstract

A lidar control device controls a lidar device including a background light cut filter that allows transmission of reflected laser light that is laser emission light reflected by an object and suppresses transmission of background light incident on the lidar device, the lidar control device including: a filter temperature acquiring unit to acquire a filter temperature of the background light cut filter; a filter characteristic acquiring unit to acquire a filter temperature characteristic of the background light cut filter; a transmission wavelength acquiring unit to acquire a transmission wavelength of the background light cut filter on the basis of the filter temperature and the filter temperature characteristic; and a control signal generating unit to generate a control signal for causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired by the transmission wavelength acquiring unit.

Inventors

Masaharu Imaki
Takayuki Nakano
Masahiro Kawai

Assignees

MITSUBISHI ELECTRIC CORPORATION

Dates

Publication Date: 20260505
Application Date: 20220422

Claims (12)

1 . A lidar control device to control a lidar device, the lidar device comprising a background light cut filter that allows transmission of reflected laser light and suppresses transmission of background light out of the reflected laser light that is reflected light of laser emission light reflected by an object to be measured and the background light incident on the lidar device, the lidar control device comprising: a filter temperature acquirer to acquire filter temperature information indicating a filter temperature of the background light cut filter comprised in the lidar device; a filter characteristic acquirer to acquire filter temperature characteristic information indicating a filter temperature characteristic of the background light cut filter; a transmission wavelength acquirer to acquire a transmission wavelength of the background light cut filter on the basis of the filter temperature information acquired by the filter temperature acquirer and the filter temperature characteristic information acquired by the filter characteristic acquirer; a control signal generator to generate a control signal for directly causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired by the transmission wavelength acquirer; an emission direction acquirer to acquire emission direction information indicating an emission direction in which the lidar device emits the laser emission light; and an angle estimator to estimate an incident angle at which the reflected laser light is incident on the background light cut filter on the basis of the emission direction information acquired by the emission direction acquirer, wherein the filter characteristic acquirer acquires the filter temperature characteristic information indicating an incident angle characteristic of the background light cut filter and the filter temperature characteristic of the background light cut filter, and the transmission wavelength acquirer acquires the transmission wavelength of the background light cut filter on the basis of the filter temperature information acquired by the filter temperature acquirer, the incident angle of the reflected laser light estimated by the angle estimator, and the filter temperature characteristic information acquired by the filter characteristic acquirer.
2 . The lidar control device according to claim 1 , further comprising: a light source characteristic acquirer to acquire light source temperature characteristic information indicating a light source temperature characteristic of a laser light source of a laser light outputter comprised in the lidar device, wherein the control signal generator generates the control signal for causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired by the transmission wavelength acquirer on the basis of the light source temperature characteristic information acquired by the light source characteristic acquirer and the transmission wavelength acquired by the transmission wavelength acquirer.
3 . The lidar control device according to claim 2 , further comprising: a light source temperature acquirer to acquire light source temperature information indicating a light source temperature of the laser light source, wherein the control signal generator generates the control signal for causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired by the transmission wavelength acquirer on the basis of the light source temperature information acquired by the light source temperature acquirer, the light source temperature characteristic information acquired by the light source characteristic acquirer, and the transmission wavelength acquired by the transmission wavelength acquirer.
4 . A lidar control device to control a lidar device, the lidar device comprising a background light cut filter that allows transmission of reflected laser light and suppresses transmission of background light out of the reflected laser light that is reflected light of laser emission light reflected by an object to be measured and the background light incident on the lidar device, the lidar control device comprising: a filter temperature acquirer to acquire filter temperature information indicating a filter temperature of the background light cut filter comprised in the lidar device; a filter characteristic acquirer to acquire filter temperature characteristic information indicating a filter temperature characteristic of the background light cut filter; a transmission wavelength acquirer to acquire a transmission wavelength of the background light cut filter on the basis of the filter temperature information acquired by the filter temperature acquirer and the filter temperature characteristic information acquired by the filter characteristic acquirer; a control signal generator to generate a control signal for directly causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired by the transmission wavelength acquirer; a reference signal extractor to receive an electric signal output from a light receiver comprised in the lidar device, which receives the reflected laser light transmitted through the background light cut filter and outputs the electric signal based on the reflected laser light that has been received, and to extract, as a reference signal, the electric signal based on laser reference light obtained by dividing, by the divider comprised in the lidar device, laser output light output from the laser light outputter comprised in the lidar device and obtaining a part of the laser output light in the electric signal; a laser wavelength determiner to determine a wavelength of the laser emission light to be emitted from the lidar device so that the laser emission light having a different wavelength is emitted from the lidar device every time the reference signal extractor extracts the reference signal; a temperature correction information generator to estimate the transmission wavelength of the background light cut filter on the basis of signal intensities of a plurality of the reference signals extracted by the reference signal extractor, to calculate a correction coefficient of the transmission wavelength of the background light cut filter on the basis of the transmission wavelength that has been estimated and the transmission wavelength acquired by the transmission wavelength acquirer, and to generate temperature correction information in which the correction coefficient that has been calculated is associated with the filter temperature information acquired by the filter temperature acquirer; a temperature correction information acquirer to acquire the temperature correction information corresponding to the filter temperature information acquired by the filter temperature acquirer from among a plurality of pieces of the temperature correction information having been generated in advance by the temperature correction information generator; and a mode selecter to select one operation mode from among at least two operation modes including a temperature correction information generating mode in which the temperature correction information is generated and a laser wavelength controlling mode for performing control for causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired by the transmission wavelength acquirer, wherein, in a case where the mode selecter has selected the temperature correction information generating mode, the control signal generator generates the control signal for causing the lidar device to emit the laser emission light having the wavelength determined by the laser wavelength determiner, in a case where the mode selecter has selected the laser wavelength controlling mode, the transmission wavelength acquirer acquires the transmission wavelength of the background light cut filter on the basis of the filter temperature information acquired by the filter temperature acquirer, the filter temperature characteristic information acquired by the filter characteristic acquirer, and the temperature correction information acquired by the temperature correction information acquirer, and the control signal generator generates the control signal for causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired by the transmission wavelength acquirer.
5 . The lidar control device according to claim 4 , further comprising: a light source characteristic acquirer to acquire light source temperature characteristic information indicating a light source temperature characteristic of a laser light source of the laser light outputter comprised in the lidar device, wherein, in a case where the mode selecter has selected the laser wavelength controlling mode, the control signal generator generates the control signal for causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired by the transmission wavelength acquirer on the basis of the light source temperature characteristic information acquired by the light source characteristic acquirer and the transmission wavelength acquired by the transmission wavelength acquirer.
6 . The lidar control device according to claim 5 , further comprising: a light source temperature acquirer to acquire light source temperature information indicating a light source temperature of the laser light source, wherein, in a case where the mode selecter has selected the laser wavelength controlling mode, the control signal generator generates the control signal for causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired by the transmission wavelength acquirer on the basis of the light source temperature information acquired by the light source temperature acquirer, the light source temperature characteristic information acquired by the light source characteristic acquirer, and the transmission wavelength acquired by the transmission wavelength acquirer.
7 . The lidar control device according to claim 5 , further comprising: an emission direction acquirer to acquire emission direction information indicating an emission direction of the laser emission light by the lidar device; and an angle estimator to estimate an incident angle at which the reflected laser light is incident on the background light cut filter on the basis of the emission direction information acquired by the emission direction acquirer, wherein the filter characteristic acquirer acquires the filter temperature characteristic information indicating an incident angle characteristic of the background light cut filter and the filter temperature characteristic of the background light cut filter, the temperature correction information generator estimates the transmission wavelength of the background light cut filter on the basis of the signal intensities of the plurality of the reference signals extracted by the reference signal extractor, calculates the correction coefficient of the transmission wavelength of the background light cut filter on the basis of the transmission wavelength that has been estimated and the transmission wavelength acquired by the transmission wavelength acquirer, and generates the temperature correction information in which the correction coefficient that has been calculated is associated with the filter temperature information acquired by the filter temperature acquirer and the emission direction information acquired by the emission direction acquirer, the temperature correction information acquirer acquires the temperature correction information corresponding to the filter temperature information and the emission direction information from among a plurality of pieces of the temperature correction information having been generated in advance by the temperature correction information generator on the basis of the filter temperature information acquired by the filter temperature acquirer and the emission direction information acquired by the emission direction acquirer, in a case where the mode selecter has selected the temperature correction information generating mode, the transmission wavelength acquirer acquires the transmission wavelength of the background light cut filter on the basis of the filter temperature information acquired by the filter temperature acquirer, the incident angle of the reflected laser light estimated by the angle estimator, and the filter temperature characteristic information acquired by the filter characteristic acquirer, and the control signal generator generates the control signal for causing the lidar device to emit the laser emission light having the wavelength determined by the laser wavelength determiner, and in a case where the mode selecter has selected the laser wavelength controlling mode, the transmission wavelength acquirer acquires the transmission wavelength of the background light cut filter on the basis of the filter temperature information acquired by the filter temperature acquirer, the incident angle of the reflected laser light estimated by the angle estimator, the filter temperature characteristic information acquired by the filter characteristic acquirer, and the temperature correction information acquired by the temperature correction information acquirer, and the control signal generator generates the control signal for causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired by the transmission wavelength acquirer.
8 . A lidar device comprising: a background light cut filter; a laser light outputter to output laser output light based on a laser light source light output from a laser light source; and a light receiver to receive reflected laser light transmitted through the background light cut filter and to output an electric signal based on the reflected laser light that has been received, wherein the lidar device further comprises: a filter temperature measurer to measure a filter temperature of the background light cut filter and to output the filter temperature that has been measured to the lidar control device as filter temperature information; a wavelength adjuster to receive a control signal generated and output by the lidar control device on the basis of the filter temperature information output by the filter temperature measurer and to directly adjust a wavelength of laser emission light emitted on the basis of the control signal; a scanning optical system to change the emission direction of the laser emission light output from the laser light outputter; and an emission direction outputter to output emission direction information indicating the emission direction having been changed by the scanning optical system to the lidar control device, wherein the wavelength adjuster receives the control signal generated and output by the lidar control device on the basis of the filter temperature information output by the filter temperature measurer and the emission direction information output by the emission direction outputter and adjusts the wavelength of the laser emission light to be emitted on the basis of the control signal.
9 . The lidar device according claim 8 , further comprising: a light source temperature measurer to measure a light source temperature of the laser light source of the laser light outputter and to output the light source temperature that has been measured as light source temperature information, wherein the wavelength adjuster receives the control signal generated and output by the lidar control device on the basis of the filter temperature information output by the filter temperature measurer and adjusts a wavelength of the laser emission light to be emitted on the basis of the control signal and the light source temperature information output by the light source temperature measurer.
10 . The lidar device according claim 8 , further comprising: a light source temperature measurer to measure a light source temperature of the laser light source of the laser light outputter and to output the light source temperature that has been measured as light source temperature information, wherein the light source temperature measurer outputs the light source temperature information to the lidar control device, and the wavelength adjuster receives the control signal generated and output by the lidar control device on the basis of the light source temperature information output by the light source temperature measurer and the filter temperature information output by the filter temperature measurer and adjusts the wavelength of the laser emission light to be emitted on the basis of the control signal.
11 . A lidar device comprising: a background light cut filter; a laser light outputter to output laser output light based on a laser light source light output from a laser light source; and a light receiver to receive reflected laser light transmitted through the background light cut filter and to output an electric signal based on the reflected laser light that has been received, wherein the lidar device further comprises: a filter temperature measurer to measure a filter temperature of the background light cut filter and to output the filter temperature that has been measured to the lidar control device as filter temperature information; a wavelength adjuster to receive a control signal generated and output by the lidar control device on the basis of the filter temperature information output by the filter temperature measurer and to directly adjust a wavelength of laser emission light emitted on the basis of the control signal; a divider to divide the laser output light output by the laser light outputter and to obtain a part of the laser output light as laser reference light, wherein the background light cut filter receives the laser reference light and the reflected laser light that is reflected light of the laser emission light reflected by the object to be measured, and the light receiver receives the reflected laser light transmitted through the background light cut filter and the laser reference light transmitted through the background light cut filter, converts the reflected laser light and the laser reference light that have been received into the electric signal, and outputs the electric signal obtained from the conversion to the lidar control device.
12 . A lidar control method to control a lidar device, the lidar device comprising a background light cut filter that allows transmission of reflected laser light and suppresses transmission of background light out of the reflected laser light that is reflected light of laser emission light reflected by an object to be measured and the background light incident on the lidar device, the lidar control method comprising: acquiring filter temperature information indicating a filter temperature of the background light cut filter comprised in the lidar device; acquiring filter temperature characteristic information indicating a filter temperature characteristic of the background light cut filter; acquiring a transmission wavelength of the background light cut filter on the basis of the filter temperature acquired and the filter temperature characteristic information acquired; generating a control signal for directly causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired; acquiring emission direction information indicating an emission direction in which the lidar device emits the laser emission light; and estimating an incident angle at which the reflected laser light is incident on the background light cut filter on the basis of the emission direction information acquired, wherein the method acquires the filter temperature characteristic information indicating an incident angle characteristic of the background light cut filter and the filter temperature characteristic of the background light cut filter, and the method acquires the transmission wavelength of the background light cut filter on the basis of the filter temperature information acquired, the incident angle of the reflected laser light estimated, and the filter temperature characteristic information acquired.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a Continuation of PCT International Application No. PCT/JP2019/043297, filed on Nov. 5, 2019, all of which is hereby expressly incorporated by reference into the present application. TECHNICAL FIELD The present invention relates to a lidar control device, a lidar control method, and a lidar device. BACKGROUND ART Lidar devices that measure a distance from a predetermined reference point to an object to be measured (hereinafter, simply referred to as “object”) by a time of flight (ToF) method are known. In such lidar devices, in order to reduce background noise, there is a lidar device (see, for example, Patent Literature 1) that includes an optical filter (hereinafter referred to as “background light cut filter”) that suppresses background light from reaching a light receiving unit that receives reflected laser light that is reflected light of laser light reflected by an object (hereinafter, simply referred to as “reflected laser light”). CITATION LIST Patent Literatures Patent Literature 1: JP 2018-44853 A SUMMARY OF INVENTION Technical Problem A background light cut filter may include an optical filter having a temperature characteristic (hereinafter, referred to as “filter temperature characteristic”), such as an etalon. A filter temperature characteristic here refers to a characteristic that the wavelength of light transmitted through an optical filter (hereinafter, referred to as “transmission wavelength”) changes when the temperature of the optical filter (hereinafter referred to as “filter temperature”) changes. In a case where the background light cut filter includes an optical filter having a filter temperature characteristic, when the filter temperature of the background light cut filter changes due to the influence of the environmental temperature or the like, the transmission wavelength of the background light cut filter changes. When the transmission wavelength of the background light cut filter changes, the transmission wavelength of the background light cut filter becomes different from the wavelength (hereinafter, referred to as “emission wavelength”) of the laser light emitted by the lidar device. When the transmission wavelength of the background light cut filter is different from the emission wavelength, the background light cut filter suppresses transmission of reflected laser light incident on the background light cut filter. In a case where the background light cut filter includes an optical filter having a filter temperature characteristic, the background light cut filter suppresses transmission of reflected laser light incident on the background light cut filter, and thus a light receiving unit of the lidar device cannot receive the reflected laser light of an intensity sufficient for performing distance measurement. In a case where the light receiving unit cannot receive reflected laser light of an intensity sufficient for performing distance measurement, the lidar device cannot perform distance measurement in high accuracy or cannot perform distance measurement itself. The present invention is intended to solve the above problem, and an object of the present invention is to provide a lidar control device capable of controlling a lidar device so that a background light cut filter included in the lidar device does not suppress transmission of reflected laser light incident on the background light cut filter even when the background light cut filter has a filter temperature characteristic and the filter temperature of the background light cut filter changes. Solution to Problem A lidar control device of the present invention controls a lidar device, the lidar device including a background light cut filter that allows transmission of reflected laser light and suppresses transmission of background light out of the reflected laser light that is reflected light of laser emission light reflected by an object to be measured and the background light incident on the lidar device, the lidar control device comprising: a filter temperature acquirer to acquire filter temperature information indicating a filter temperature of the background light cut filter comprised in the lidar device; a filter characteristic acquirer to acquire filter temperature characteristic information indicating a filter temperature characteristic of the background light cut filter; a transmission wavelength acquirer to acquire a transmission wavelength of the background light cut filter on the basis of the filter temperature information acquired by the filter temperature acquirer and the filter temperature characteristic information acquired by the filter characteristic acquirer; and a control signal generator to generate a control signal for causing the lidar device to emit the laser emission light having a wavelength corresponding to the transmission wavelength acquired by the transmission wavelength acquirer. Advantageous Effects of Invention According to the