scholarly journals A Novel Skylight Orientation Sensor for Autonomous Navigation

2021 ◽  
Author(s):  
Yuanyi Fan ◽  
Ran Zhang ◽  
Ze Liu ◽  
Jinkui Chu
Keyword(s):  
Autonomous Navigation ◽  
Symmetry Axis ◽  
Angle Measurement ◽  
Degree Of Polarization ◽  
Polarization Distribution ◽  
Reference Axis ◽  
Skylight Polarization ◽  
Application Potential ◽  
Orientation Sensor ◽  
Linear Polarizer

<a></a>The angle of the polarization (AOP) and the degree of polarization (DOP) of the scattered skylight are symmetrically distributed concerning the solar meridian. Based on the symmetry of the skylight polarization distribution pattern, this paper proposes a novel skylight orientation sensor consists of a camera, an S-waveplate, and a linear polarizer. The skylight orientation sensor is using the image polarization encoding capability of the S-waveplate and the linear polarizer to convert the skylight polarization information into the image’s symmetry axis extraction, which has the advantages of no resolution loss and instantaneous field of view error. The symmetry axis in the image is consistent with the solar meridian. Therefore, the angle between the solar meridian and the skylight orientation sensor reference axis can be obtained without calculating the polarization information, which is also beneficial for real-time performance. The angle measurement accuracy and uncertainty of the skylight orientation sensor are verified by numerical simulation and outdoor experiments. The results demonstrate that the skylight orientation sensor has good application potential in autonomous navigation.

scholarly journals A Novel Skylight Orientation Sensor for Autonomous Navigation

2021 ◽  
Author(s):  
Yuanyi Fan ◽  
Ran Zhang ◽  
Ze Liu ◽  
Jinkui Chu
Keyword(s):  
Autonomous Navigation ◽  
Symmetry Axis ◽  
Angle Measurement ◽  
Degree Of Polarization ◽  
Polarization Distribution ◽  
Reference Axis ◽  
Skylight Polarization ◽  
Application Potential ◽  
Orientation Sensor ◽  
Linear Polarizer

<a></a>The angle of the polarization (AOP) and the degree of polarization (DOP) of the scattered skylight are symmetrically distributed concerning the solar meridian. Based on the symmetry of the skylight polarization distribution pattern, this paper proposes a novel skylight orientation sensor consists of a camera, an S-waveplate, and a linear polarizer. The skylight orientation sensor is using the image polarization encoding capability of the S-waveplate and the linear polarizer to convert the skylight polarization information into the image’s symmetry axis extraction, which has the advantages of no resolution loss and instantaneous field of view error. The symmetry axis in the image is consistent with the solar meridian. Therefore, the angle between the solar meridian and the skylight orientation sensor reference axis can be obtained without calculating the polarization information, which is also beneficial for real-time performance. The angle measurement accuracy and uncertainty of the skylight orientation sensor are verified by numerical simulation and outdoor experiments. The results demonstrate that the skylight orientation sensor has good application potential in autonomous navigation.

Empirical Polarization Distribution Models for CLARREO-Imager Intercalibration

2016 ◽  
Vol 33 (3) ◽  
pp. 439-451 ◽  
Author(s):  
D. Goldin ◽  
C. Lukashin
Keyword(s):  
Linear Polarization ◽  
Infrared Imaging ◽  
Solar Spectrum ◽  
National Research Council ◽  
Real Data ◽  
Radiative Transfer Model ◽  
Degree Of Polarization ◽  
Transfer Model ◽  
Distribution Models ◽  
Polarization Distribution

AbstractPolarization effects bias the performance of various existing passive spaceborne instruments, such as MODIS and the Visible Infrared Imaging Radiometer Suite (VIIRS), as well as geostationary imagers. It is essential to evaluate and correct for these effects in order to achieve the required accuracy of the total reflectance at the top of the atmosphere.In addition to performing highly accurate decadal climate change observations, one of the objectives of the Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission recommended by the National Research Council for launch by NASA is to provide the on-orbit intercalibration with the imagers over a range of parameters, including polarization. Whenever the on-orbit coincident measurements are not possible, CLARREO will provide the polarization distributions constructed using the adding–doubling radiative transfer model (ADRTM), which will cover the entire reflected solar spectrum. These ADRTM results need to be validated using real data. To this end the empirical polarization distribution models (PDMs) based on the measurements taken by the Polarization and Anisotropy of Reflectances for Atmospheric Sciences Coupled with Observations from a Lidar (PARASOL) mission were developed. Examples of such PDMs for the degree of polarization and the angle of linear polarization for the cloudless ocean scenes are shown here. These PDMs are compared across the three available PARASOL polarization bands, and the effect of aerosols on them is examined. The PDM-derived dependence of the reflectance uncertainty on the degree of polarization for imagers, such as MODIS or VIIRS, after their intercalibration with the CLARREO instrument is evaluated. The influence of the aerosols on the reflectance uncertainty is examined. Finally, the PDMs for the angle of linear polarization is cross-checked against the single-scattering approximation.

Reconstruction of the probability density function by means of the degree of polarization for one-photon mixed states

Open Physics ◽  
2013 ◽  
Vol 11 (4) ◽  
Author(s):  
Lukasz Michalik ◽  
Andrzej Domanski
Keyword(s):  
Probability Density ◽  
Thought Experiment ◽  
Reference Beam ◽  
Quantum Tomography ◽  
Stokes Parameters ◽  
Degree Of Polarization ◽  
Probability Density Distribution ◽  
Mixed States ◽  
State Of Polarization ◽  
Linear Polarizer

AbstractIn this paper the authors discuss an alternative way for reconstructing one-photon mixed states of a partially polarized optical field. The task is to represent the probability density distribution describing these kind of states with the Stokes parameters which also characterize the effective state of polarization. These parameters can be measured by means of the degree of polarization with an experimental setup containing a rotating linear polarizer and a circular polarizer. A thought experiment is presented which assumes that the measurement is undertaken on an analyzed beam coupled with a reference beam containing photons polarized in a well-known way. The method discussed in the paper is an alternative for the most commonly used quantum tomography approach.

scholarly journals Polarized Skylight Navigation in Insects: Model and Electrophysiology of e-Vector Coding by Neurons in the Central Complex

2008 ◽  
Vol 99 (2) ◽  
pp. 667-682 ◽  
Author(s):  
Midori Sakura ◽  
Dimitrios Lambrinos ◽  
Thomas Labhart
Keyword(s):  
Vision System ◽  
Gain Control ◽  
Central Complex ◽  
Degree Of Polarization ◽  
Insect Brain ◽  
Atmospheric Conditions ◽  
Compass Orientation ◽  
Vector Coding ◽  
Skylight Polarization ◽  
Vector Orientation

Many insects exploit skylight polarization for visual compass orientation or course control. As found in crickets, the peripheral visual system (optic lobe) contains three types of polarization-sensitive neurons (POL neurons), which are tuned to different (∼60° diverging) e-vector orientations. Thus each e-vector orientation elicits a specific combination of activities among the POL neurons coding any e-vector orientation by just three neural signals. In this study, we hypothesize that in the presumed orientation center of the brain (central complex) e-vector orientation is population-coded by a set of “compass neurons.” Using computer modeling, we present a neural network model transforming the signal triplet provided by the POL neurons to compass neuron activities coding e-vector orientation by a population code. Using intracellular electrophysiology and cell marking, we present evidence that neurons with the response profile of the presumed compass neurons do indeed exist in the insect brain: each of these compass neuron-like (CNL) cells is activated by a specific e-vector orientation only and otherwise remains silent. Morphologically, CNL cells are tangential neurons extending from the lateral accessory lobe to the lower division of the central body. Surpassing the modeled compass neurons in performance, CNL cells are insensitive to the degree of polarization of the stimulus between 99% and at least down to 18% polarization and thus largely disregard variations of skylight polarization due to changing solar elevations or atmospheric conditions. This suggests that the polarization vision system includes a gain control circuit keeping the output activity at a constant level.

scholarly journals OPTICAL POLARIZED EFFECTS FOR QUANTITATIVE REMOTE SENSING

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 593-598
Author(s):  
L. Yan ◽  
Y. Li ◽  
H. Mortimer ◽  
R. Zhang ◽  
J. Peltoniemi ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Linear Polarization ◽  
Rayleigh Scattering ◽  
Weather Conditions ◽  
Degree Of Polarization ◽  
Gradual Change ◽  
Distribution Law ◽  
Solar Altitude ◽  
Quantitative Remote Sensing ◽  
Skylight Polarization

Abstract. Polarization is one of the four basic physical properties of solar radiation. After the solar radiation reaches the surface of these media, it reflects, scatters or refracts, and exhibits different degrees of polarization. We use Rayleigh scattering model to get the simulation results of the sky polarization field. We use polarized fisheye camera to collect the sky polarization image, and calculate the distribution pattern of DOLP (degree of linear polarization) and AOLP (azimuth of linear polarization) of the skylight. The stability and gradual change of the degree of polarization in the zenith direction are verified, and the distribution law and daily change law of the degree of polarization in the sky are obtained. With the increase of the solar altitude angle, the degree of polarization will decrease. We also observed the skylight polarization in different weather conditions.

scholarly journals Skylight Polarization patterns and Animal Orientation

1982 ◽  
Vol 96 (1) ◽  
pp. 69-91 ◽  
Author(s):  
MICHAEL L. BRINES ◽  
JAMES L. GOULD
Keyword(s):  
Rayleigh Scattering ◽  
Polarized Light ◽  
Processing System ◽  
Light Polarization ◽  
Degree Of Polarization ◽  
Atmospheric Conditions ◽  
Apparent Paradox ◽  
Skylight Polarization ◽  
Visible Wavelengths ◽  
Vector Orientation

1. Although many invertebrate animals orient by means of ultraviolet sky-light polarization patterns, existing measurements of these patterns are inadequate for full analysis of the biologically relevant information available from the sky. To fill this gap we have used a precision scanning polarimeter to measure simultaneously the intensity, degree, and direction of vibration (E-vector orientation) of polarized light at 5° intervals over the sky. The resulting sky maps were constructed for u.v. (350 nm) and visible wavelengths (500 and 650 nm) under a variety of atmospheric conditions. 2. Our measurements confirmed that the patterns of radiance and degree of polarization of skylight are highly variable and hence unreliable as orientation cues; but patterns of E-vector orientation are relatively stable and predictable over most of the sky under all but very hazy or overcast conditions. 3. The observed E-vector patterns correspond more closely to predictions based on first order (Rayleigh) scattering at 650 and 500 nm than at 350 nm. This is true both in terms of absolute accuracy and the proportion of the sky with relatively ‘correct’ information. Yet most insects respond to polarization patterns only at u.v. wavelengths. This apparent paradox can perhaps be resolved by assuming that there is no great selective advantage for any particular wavelength when large areas of blue sky are visible, but that under special and difficult conditions ultraviolet has advantages over longer wavelengths. Measurements under partially cloud-covered sky, for instance, or under extensive vegetation, show that both spuriously polarized and unpolarized light resulting from reflexions present more troublesome interference at longer wavelengths than in the u.v. 4. The accuracy of orientation achieved by dancing honey bees appears to be greater than can readily be accounted for by assuming that they use a strictly geometrical or analytical processing system for their orientation to polarized light.

How to Get the Solar Direction from Skylight Polarization for Satellite Autonomous Navigation

2014 ◽  
Vol 577 ◽  
pp. 434-437
Author(s):  
He Huang ◽  
Jun Zhou ◽  
Ying Ying Liu
Keyword(s):  
Autonomous Navigation ◽  
Satellite Navigation ◽  
New Method ◽  
Vector Polarization ◽  
Important Clue ◽  
Skylight Polarization ◽  
Polarization Sensor

The solar direction is an important clue for satellite autonomous navigation. A new method for obtaining the solar direction from skylight polarization for satellite navigation is discussed. The new method is using two E-vector polarization sensors to get solar direction, and the view field of the polarization sensor is discussed.

An autonomous navigation system integrated with air data and bionic polarization information

2019 ◽  
Vol 41 (13) ◽  
pp. 3679-3687
Author(s):  
Xiaoyu Guo ◽  
Jian Yang ◽  
Tao Du ◽  
Wanquan Liu
Keyword(s):  
Navigation System ◽  
Autonomous Navigation ◽  
Angle Measurement ◽  
Measurement Unit ◽  
Integrated Navigation ◽  
Integrated Navigation System ◽  
Aerial Vehicle ◽  
Polarization Sensor ◽  
Output Information ◽  
Autonomous Navigation System

One of the most significant challenges for an unmanned aerial vehicle (UAV) is to autonomously navigate in complex environments, as the signals from the global positioning system (GPS) are subject to disturbance and interference. To improve the autonomy and availability of the UAV navigation system without GPS, we design a new autonomous navigation system and implement it for real applications in this paper, in which one integrates the inertial measurement unit (IMU), the bionic polarization sensor (BPS), and the air data system (ADS). The BPS can provide effective heading angle measurement, and the ADS is used to output information for continuous velocity and height. The combination of BPS and ADS is a solution the inertial error drift. Kalman filter is selected to estimate the error state of the integrated navigation system based on the measurements from the BPS and ADS, and then the estimation is used to correct the navigation system error in real time. The simulation and experimental results have shown that the new integrated navigation system can perform with high precision and autonomy without GPS signal.

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