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A photodiode based miniature sun sensor

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Measurement Science and Technology
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Xiaozhou Lü
Xiaozhou Lü
Xiaozhou Lü
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Yebo Tao
Yebo Tao
Yebo Tao
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Kai Xie at Xidian University
Kai Xie
Songlin Wang
Songlin Wang
Songlin Wang
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Abstract and Figures

The solar vector is one of the most important parameters for attitude control of nanosatellites. This attitude control must be achieved without the sensors adding significantly to its size or mass. This paper presents a photodiode-based miniature sun sensor, which consists of two triangular pyramidal sensor unit structures, with each unit comprising three micro-silicon photodiodes. The two sensor units are installed on the diagonal of the nanosatellite to form a complete sun sensor capable of achieving a full-field range of solar vector measurements. In this paper, the mathematical model of the short-circuit currents of the silicon photodiodes as a function of the solar vector coordinates is deduced. A sensor sample was built and installed on a nanosatellite model, and the temperature compensation coefficient of the silicon photodiodes was obtained experimentally. The dynamic characteristic, linearity, hysteresis and repeatability of the component were measured. The sun sensor introduced in this paper can be placed on any satellite platform to allow a full range solar vector measurement, and this would result in an increase of only 1.86 g and 0.9 cm³ of the satellite's mass and volume, respectively.
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1. Introduction
Accurate control of nanosatellites’ attitude is a prerequi-
site and foundation of space formation ight. As the Earth’s
nearest star, the sun is the ideal reference point [1], because
compared with other stars, the sun’s light has the advantage of
high brightness, high ray parallelism and high SNR (Signal-to-
Noise Ratio) when it reaches Earth orbit [2, 3]. Furthermore,
the relative position of the satellite to sun light (i.e. the solar
vector) is almost independent of the satellite’s trajectory when
in near earth orbit, so the azimuthal information of the satellite
is usually obtained by the sun sensor. The sun sensor deter-
mines the position of the sun in the coordinate system of the
sensor’s body by measuring the vector of the solar ray. Then,
the satellite obtains the position of the sun in the coordinate
system of the satellite body and nally obtains the attitude of
the satellite [4].
At present, sun sensors can be divided into three types: (1).
Analog sun sensors, which, based on the specic structure of
the light-sensitive material, produce a sunlight stripe asso-
ciated with the solar vector through a grating. These sen-
sors output the electrical signal associated with the angle to
measure the solar vector [5, 6]. (2) Digital sun sensors, which
use CCD or CMOS APS technology to capture the sun’s
image. The solar vector can be derived from the image with
the help of a digital image processing algorithm [7–10]. (3)
Sun sensors using solar panels by means of multiplexing,
where the sunlight incident angle and the photocurrent of the
solar panel is a cosine function and is used to achieve the solar
vector measurements [11, 12].
The sun sensor types mentioned above achieve solar vector
measurement, have been successfully applied to satellites, and
are associated with the advantages of high accuracy and large
eld of view. Unfortunately, these sun sensors still face the
following problems when used in nanosatellite platforms: (1).
Analog sun sensors have a large optical structure and a single
such sun sensor cannot perform full eld-of-view measure-
ments [5, 6]. (2). Digital sun sensors consume more power
Measurement Science and Technology
A photodiode based miniature sun sensor
XiaozhouLü1, YeboTao1, KaiXie1, SonglinWang1, XiaopingLi1,
WeiminBao1 and RenjieChen2
1 School of Aerospace Science & Technology, Xidian University, Xi’an 710071, People’s Republic
of China
2 School of Materials Science & Engineering, Beijing Key Laboratory of Environmental Science
and Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
E-mail: lxz@uw.edu (X Lü) and chenrj@bit.edu.cn (R Chen)
Received 23 January 2017
Accepted for publication 21 February 2017
Published 15 March 2017
Abstract
The solar vector is one of the most important parameters for attitude control of nanosatellites.
This attitude control must be achieved without the sensors adding signicantly to its size or
mass. This paper presents a photodiode-based miniature sun sensor, which consists of two
triangular pyramidal sensor unit structures, with each unit comprising three micro-silicon
photodiodes. The two sensor units are installed on the diagonal of the nanosatellite to form a
complete sun sensor capable of achieving a full-eld range of solar vector measurements. In
this paper, the mathematical model of the short-circuit currents of the silicon photodiodes as a
function of the solar vector coordinates is deduced. A sensor sample was built and installed on
a nanosatellite model, and the temperature compensation coefcient of the silicon photodiodes
was obtained experimentally. The dynamic characteristic, linearity, hysteresis and repeatability
of the component were measured. The sun sensor introduced in this paper can be placed on
any satellite platform to allow a full range solar vector measurement, and this would result in
an increase of only 1.86 g and 0.9 cm3 of the satellite’s mass and volume, respectively.
Keywords: sun sensor, nanosatellite, solar vector
(Some guresmay appear in colour only in the online journal)
X Lü etal
Printed in the UK
055104
MSTCEP
© 2017 IOP Publishing Ltd
28
Meas. Sci. Technol.
MST
10.1088/1361-6501/aa61b5
Paper
5
Measurement Science and Technology
IOP
2017
1361-6501
1361- 6501/17/ 055104 +7$3 3. 00
https://doi.org/10.1088/1361-6501/aa61b5
Meas. Sci. Technol. 28 (2017) 055104 (7pp)
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... Flight vehicles are considered as one of the key flight equipment types in the 21st century since they can fly at ultra-high-speed in the near space and have the functions of aircraft, carriers and spacecraft, etc. [1]. The surface of flight vehicles (such as aerospace vehicle, Low Earth Orbit (LEO) satellites, near-space aircrafts, Unmanned Aerial Vehicles (UAVs) and drones) suffer the micro-pressure from high-altitude thin air when they are flying at high speed. ...
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