Spectrum measurement device

• US 9,305,220 B2
• Filed: 04/08/2011
• Issued: 04/05/2016
• Est. Priority Date: 04/09/2010
• Status: Active Grant

• Current Assignee: NEC Corporation, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: NEC Corporation, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Funayama, Ryuji, Kawamata, Shinya, Yoshikawa, Yumiko, Ishi, Tsutomu
• Primary Examiner(s): Ratcliffe, Luke
• Assistant Examiner(s): Woldemaryam, Assres H
• Application Number:
  US13/639,378
• Publication Number:
  US 20130038857A1
• Time in Patent Office: 1,824 Days
• Field of Search: 356/4.07, 356/326, 356/402, 701/36, 340/904, 340/901
• US Class Current: 1/1
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G06V 10/143 Sensing or illuminating at different wavelengths
• CPC Class Codes: G06V 20/58 Recognition of moving objects or obstacles, e.g. vehicles or pedestrians; Recognition of traffic objects, e.g. traffic signs, traffic lights or roads
• CPC Class Codes: G08G 1/165 for passive traffic, e.g. including static obstacles, trees
• CPC Class Codes: G08G 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes

Abstract

A spectrum measurement device that recognizes objects to be measured on the basis of spectral data of observed light that is detected by a spectrum sensor capable of measuring wavelength information and light intensity information. The spectrum measurement device comprises a lighting device capable of projecting light that includes a wavelength region with a high atmospheric absorption index and recognizes the distance from a vehicle to an object to be measured through a computation that uses spectral data of observed light that is obtained from the object to be measured whereupon light of at least the wavelength region with the high atmospheric absorption index is projected.

Claims

1. A spectrum measurement device for recognizing a measurement target based on a spectral data set of observed light detected by a spectral sensor capable of obtaining wavelength information and light intensity information, the spectrum measurement device comprising:

a lighting device on the spectrum measurement device irradiating light to the measurement target including light in a first wavelength band and light in a second wavelength band, the first wavelength band exhibiting a higher atmospheric absorption coefficient than that of the second wavelength band; and

circuitry configured to calculate a distance to the measurement target through an arithmetic operation using the spectral data set of observed light from the measurement target irradiated at least with the light in the first wavelength band exhibiting the higher atmospheric absorption coefficient and without removing an influence of ambient light from the spectral data set of observed light, and the circuitry is configured to identify the measurement target using the spectral data set of observed light from the measurement target irradiated with light in the second wavelength band.

2. The spectrum measurement device according to claim 1, wherein

the circuitry is configured to determine a reflectance specific to the identified measurement target, and

the circuitry is configured to calculate the distance from an observation point of the spectral data set to the measurement target as a ratio of light output intensity of the lighting device based on the determined reflectance to light intensity of observed light detected by the spectral sensor.

3. The spectrum measurement device according to claim 2, wherein

the circuitry is configured to access a database having previously registered spectral data sets indicating spectral reflectances of a plurality of measurement targets, the circuitry is configured to identify the measurement target through comparison of the spectral data set of the observed light by the spectral sensor when the measurement target is irradiated with the light in the second wavelength band with the plurality of spectral data sets registered in the database, and to determine the reflectance specific to the measurement target, and

the light intensity of the observed light detected by the spectral sensor is a value obtained as intensity of light reflected by the measurement target when the light in the first wavelength band exhibiting the higher atmospheric absorption coefficient is being irradiated to the measurement target.

4. The spectrum measurement device according to claim 3, wherein the circuitry is configured to calculate the distance (L) from the observation point of the spectral data set to the measurement target using the following expression

L⁴=(PP/Pr)×

R×

k,

where R represents the reflectance determined by the circuitry, PP represents the light output intensity of the lighting device, Pr represents the light intensity of the observed light detected by the spectral sensor, and k represents a correction factor indicating a relationship between the light output intensity PP and the light intensity Pr.

5. The spectrum measurement device according to claim 1, wherein the circuitry is configured to recognize a change in relative distance between the observation point of the spectral data set and the measurement target through an arithmetic operation for determining a change over time of the spectral data set of the observed light from the measurement target irradiated with the light in the first wavelength band exhibiting the higher atmospheric absorption coefficient.

6. The spectrum measurement device according to claim 5, wherein the arithmetic operation for determining a change over time of the spectral data set is either a difference operation or a division operation on spectral data sets obtained at different points in time.

7. The spectrum measurement device according to claim 5, wherein the circuitry is configured to identify the measurement target based on the spectral data set of the observed light detected by the spectral sensor.

8. The spectrum measurement device according to claim 7, wherein when the measurement target is being irradiated with the light in the first wavelength band exhibiting the higher atmospheric absorption coefficient, the circuitry is configured to identify the measurement target irradiated with the light based on a comparison between the spectral data set of the observed light detected by the spectral sensor and the spectral data sets on a plurality of measurement targets previously registered in a database.

9. The spectrum measurement device according to claim 1, wherein

the spectral sensor and the lighting device are both mounted on a vehicle, and

the measurement target to be recognized is an object present in the vicinity of the vehicle.

10. The spectrum measurement device according to claim 2, wherein

the circuitry is configured to identify the measurement target based on the spectral data set of the observed light by the spectral sensor when the measurement target is irradiated with the light in the second wavelength band, and to determine the reflectance specific to the measurement target, and

the light intensity of the observed light detected by the spectral sensor is a value obtained as intensity of light reflected by the measurement target when the light in the first wavelength band exhibiting the higher atmospheric absorption coefficient is being irradiated to the measurement target.

11. The spectrum measurement device according to claim 10, wherein the circuitry is configured to calculate the distance (L) from the observation point of the spectral data set to the measurement target using the following expression

L⁴=(PP/Pr)×

R×

k,

where R represents the reflectance determined by the circuitry, PP represents the light output intensity of the lighting device, Pr represents the light intensity of the observed light detected by the spectral sensor, and k represents a correction factor indicating a relationship between the light output intensity PP and the light intensity Pr.

13. The spectrum measurement device according to claim 1, wherein the circuitry is configured to calculate the distance to the measurement target and to identify the measurement target at a same time.

14. The spectrum measurement device according to claim 1, wherein the circuitry is configured to calculate the distance to the measurement target through the arithmetic operation using the spectral data set of observed light from the measurement target irradiated only with the light in the first wavelength band exhibiting the higher atmospheric absorption coefficient.

15. The spectrum measurement device according to claim 1, wherein the lighting device includes an LED.

12. A spectrum measurement device for recognizing a measurement target based on a spectral data set of observed light detected by a spectral sensor capable of obtaining wavelength information and light intensity information, the spectrum measurement device comprising:

a lighting device irradiating light to the measurement target including light in a first wavelength band and light in a second wavelength band, the first wavelength band exhibiting a higher atmospheric absorption coefficient than that of the second wavelength band; and

circuitry configured to calculate a distance to the measurement target through an arithmetic operation using the spectral data set of observed light from the measurement target irradiated at least with the light in the first wavelength band exhibiting the higher atmospheric absorption coefficient, and

the circuitry is configured to calculate the distance (L) from an observation point of the spectral data set to the measurement target using the following expression

L⁴=(PP/Pr)×

R×

k,

where R represents a reflectance determined by the circuitry, PP represents a light output intensity of the lighting device, Pr represents a light intensity of the observed light detected by the spectral sensor, and k represents a correction factor indicating a relationship between the light output intensity PP and the light intensity Pr.