Optimum spectral bands for active vision systems

Patent metadata

Field	Value
Publication number	US-10508952-B1
Application number	US-201816176295-A
Country	US
Kind code	B1
Filing date	Oct 31, 2018
Priority date	Oct 31, 2018
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

A vision system for monitoring areas of interest having a system for receiving an optical input, outputting a signal, and processing the signal. The system is configured to measure the radiance in spectral bands in which solar radiation is reduced substantially due to absorption by atmospheric constituents. This mitigates the negative effects of solar radiation such as sun glare. The system is configured to output a resultant detection signal in response to the measurements in the spectral bands selected.

First claim

What is claimed is:

1. An active vision system for monitoring areas of interest, the vision system comprising:
an illumination source outputting energy to the areas of interest in at least one spectral band in which solar radiation is reduced substantially due to absorption by atmospheric constituents, the at least one spectral band being selected from the group consisting of less than 0.3, 0.90-0.95 μm, 1.10-1.15 μm, 1.35-1.50 μm, 1.80-2.06 μm, and 2.50-3.05 μm;
an optics system receiving an optical input in the at least one spectral band from the areas of interest and outputting an optics signal; and
a processing system receiving the optics signal, the processing system configured to measure the optics signal, the processing system configured to output a resultant signal in response to the measurements in the at least one spectral band,
wherein the optics system comprises at least one detector configured to measure radiance in the at least one spectral band adjacent to a crossover point of the imaginary part of the index of refraction of liquid water and ice, the at least one detector configured to measure the radiance in the first band portion of the at least one spectral band having wavelengths on a first side of the crossover point and output a first band signal, the at least one detector configured to measure the radiance in a second band portion of the at least one spectral band having wavelengths on a second side of the crossover point and output a second band signal, the second side of the crossover point being opposite of the first side; and
the processing system configured to detect the presence of water, snow, frost, ice, and water/ice mixtures using non-transitory software and look-up tables to estimate the surface condition and output an alert when a predetermined condition is detected based on the radiance measurements in the first band portion and the second band portion.

2. The vision system according to claim 1 wherein the location and width of the first and second band portions of the at least one spectral band are selected such that water causes the first band signal and the second band signal to move in an opposite direction than ice.

3. The vision system according to claim 1 , wherein the at least one detector comprises a camera and spectral filters.

4. The vision system according to claim 1 , wherein the processing system is configured to quantify a hazard level using a road condition assessment matrix relating the detection signal and a measured temperature with the coefficient of friction between a vehicle's wheels and a road surface.

5. The vision system according to claim 1 comprising:
an interface system coupled to a display configured to alert an operator.

6. The vision system according to claim 1 comprising:
an automation system of a vehicle configured to respond to the alert from the processing system.

7. The vision system according to claim 1 comprising:
an interface system operably coupled to a vehicle, the interface system configured to prevent unsafe vehicle driving configurations by reducing a vehicle speed or deviating from a hazard in response to the alert.

8. The vision system according to claim 1 ,
wherein the atmospheric constituents are chosen from the group consistently of atmospheric ozone (O 3 ), carbon dioxide (CO 2 ), and water vapor (H 2 O).

9. The vision system according to claim 1 , wherein the first band portion is about 1.908 to 1.968 μm and the second band portion is about 2.000 to 2.060 μm.

10. A vision system for detecting the condition of the road ahead of a vehicle, the condition of the airspace ahead of a vehicle, or obstacles, or for mapping terrain, navigating, or for detecting surface or atmospheric constituents of interest, and the system comprising:
a measurement system configured to measure in spectral bands in which solar radiation is reduced substantially because of absorption by atmospheric constituents in order to mitigate the negative effects of solar radiation and output a determination signal.

11. The vision system according to claim 10 , wherein the measurement system comprises a camera detector.

12. The vision system according to claim 10 , wherein the measurement system comprises a light source configured to illuminate an area of interest.

13. The vision system according to claim 10 comprising:
an interface system coupled to a display configured to alert an operator.

14. The vision system according to claim 10 comprising:
an automation system of a vehicle configured to respond to the alert from the processing system.

15. The vision system according to claim 10 comprising:
an interface system operably coupled to a vehicle, the interface system configured to prevent unsafe vehicle driving configurations by reducing a vehicle speed or deviating from a hazard in response to the alert.

16. A detection method for detecting an obstacle, a surface, or constituents of interest, the method comprising:
measuring a determination signal in spectral bands in which solar radiation is reduced substantially because of absorption by atmospheric constituents in order to mitigate negative effects of solar radiation such as sun glare.

17. The detection method according to claim 16 wherein:
radiance is measured in a first band portion and a second band portion adjacent to a crossover point of the imaginary part of the index of refraction of liquid water and ice and outputting a first band signal and a second band signal respectively, the radiance in the first band portion having wavelengths in a spectral band on a first side of the crossover point and in the second band portion having wavelengths in a spectral band on a second opposing side of the crossover point; and
the ratio of the first band signal to the second band signal is determined and the ratio is compared to predetermined critical ratios to output a determination signal indicating the presence of water or ice.

18. The detection method according to claim 17 wherein the location and width of the first band portion and the second band portion are adjusted such that water pushes the first band signal and the second band signal in the opposite direction than ice.

19. The detection method according to claim 16 , wherein the spectral bands are about 1.908 to 1.968 μm and about 2.000 to 2.060 μm.

Assignees

• Univ Michigan Regents

Inventors

• Rennó Nilton O
• Hughes Keith C

Classifications

• G01J2003/4435

  Measuring ratio of two lines, e.g. internal standard · CPC title

• G01J2003/1213

  Filters in general, e.g. dichroic, band · CPC title

• G01J3/443

  Emission spectrometry · CPC title

• G01J3/427

  Dual wavelengths spectrometry · CPC title

• G01J3/36

  Investigating two or more bands of a spectrum by separate detectors · CPC title