Current and Speed Control Operating Modes of a Reaction Wheel

2014 ◽  
Vol 706 ◽  
pp. 170-180 ◽  
Author(s):  
Valdemir Carrara ◽  
Helio Koiti Kuga
Keyword(s):  
Fiber Optics ◽  
Attitude Control ◽  
High Reliability ◽  
Speed Control ◽  
Experimental Results ◽  
Space Environment ◽  
Air Bearing ◽  
Reaction Wheel ◽  
Pointing Error ◽  
Speed Mode

This paper presents some approaches to the design and some experimental results for current and speed control loops of a reaction wheel (RW). Reaction wheels are largely employed in satellite attitude control due to its large range of torque capability, small power consumption and high reliability. However, to achieve such performance the RW design shall deal with several restrictions, such as to support the space environment hazards (radiation, vacuum, high and fast temperature variation), and launch requirements (vibration, noise and choke). In this work some experimental results of an air-bearing table attitude control equipped with a Fiber Optics Gyro (FOG), a reaction wheel and a small fan will be presented. The RW is controlled by speed reference, and a second speed mode control similar to the first one was implemented in an external computer. Both were then compared by means of the air-bearing attitude control performance during the wheel zero-speed crossing. The results showed that the controllers have similar performance, as expected, and the maximum attitude pointing error remained below 0.08 degrees, which complies with the attitude requirements of Earth pointing satellites.

Disturbance Observer-based Attitude Control of The Air-Bearing Platform using a Reaction Wheel

2021 ◽  
Author(s):  
Harry Septanto ◽  
Farohaji Kurniawan ◽  
Bambang Setiadi ◽  
Edi Kurniawan ◽  
Djoko Suprijanto
Keyword(s):  
Attitude Control ◽  
Disturbance Observer ◽  
Air Bearing ◽  
Reaction Wheel

Reaction wheel attitude control for space vehicles

1959 ◽  
Vol 4 (3) ◽  
pp. 139-149 ◽  
Author(s):  
R. Froelich ◽  
H. Papapoff
Keyword(s):  
Attitude Control ◽  
Space Vehicles ◽  
Reaction Wheel

Design of Semi-Physical Simulation for Small Satellite by Virtual Display

2011 ◽  
Vol 130-134 ◽  
pp. 2684-2687 ◽  
Author(s):  
Kai Xu ◽  
Yan Lv ◽  
Guang Jin
Keyword(s):  
Control System ◽  
Real Time ◽  
Attitude Control ◽  
Physical Simulation ◽  
Simulation System ◽  
Space Environment ◽  
Small Satellite ◽  
Attitude Control System ◽  
Actual Environment ◽  
Virtual Display

Semi-physical simulation of attitude control system is the more synthetically test and verify for designing of small satellite control system. It is an important means of small satellite development. However, the results of current semi-physical simulation system have a lot of non-intuitive. Compare with the actual environment, the simulation environment still has striking disparity. So the shortcomings affect precision of simulation. Based on the virtual display technology, the group semi-physical simulation system has been constructed for attitude control of small satellite due to the combination with xPC real-time environment, the simulation computer, high-precision single-axis air-bearing turntable, reaction wheel, air thrust device, fiber gyroscopes, sensors synchronizer, power subsystem and wireless devices virtual display computer etc. Semi-physical simulation achieved the visual simulation in orbit and tracked new information of virtual environment of space into real-time simulation computer. Simulation results show that the simulation system for real-time attitude and orbit position of small satellite semi-physical simulation has an excellent display effect. At the same time, Real-time transfuse of orbit information provides a more accurate space environment simulation. The simulation system of small satellite attitude control to design and evaluate the more direct and convenient.

Wireless probes for measuring vertical temperature profiles in borehole heat exchangers (BHEs)

2021 ◽  
Author(s):  
Simon Schüppler ◽  
Roman Zorn ◽  
Hagen Steger ◽  
Philipp Blum
Keyword(s):  
Measurement Uncertainty ◽  
Fiber Optics ◽  
Heat Exchangers ◽  
Measurement Errors ◽  
High Reliability ◽  
Temperature Profiles ◽  
Measured Temperature ◽  
Distributed Temperature Sensing ◽  
Vertical Temperature ◽  
Borehole Heat Exchangers

<p>The measurement of the undisturbed ground temperature (UGT) serves to design low-temperature geothermal systems, in particular borehole heat exchangers (BHEs), and to monitor shallow aquifers. Wireless and miniaturized probes such as the Geosniff (GS) measurement sphere, which are characterized by an autarkic energy supply and equipped with pressure and temperature sensors, are increasingly being used for the measurement of highly resolved vertical temperature profiles. The measurement probe sinks along the course of the BHE with a selectable measurement frequency to the bottom of the BHE and is useable for initial measurements as well as long term groundwater monitoring. To ensure quality assurance and further improvement of this emerging technology, the analysis of measurement errors and uncertainties of wireless temperature measurements (WTMs) is indispensable. Thus, we provide an empirical laboratory analysis of random, systematic, and dynamic measurement errors, which lead to the measurement uncertainty of WTMs using the GS as a representative device. We subsequently transfer the analysed uncertainty to measured vertical temperature profiles of the undisturbed ground at a BHE site in Karlsruhe, Germany. The precision and accuracy of 0.011 K and -0.11 K, respectively, ensure a high reliability of the GS measurements. The largest measurement uncertainty is obtained within the first five meters of descent resulting from the thermal time constant τ of 4 s. The measured temperature profiles are qualitatively compared with common Distributed Temperature Sensing (DTS) using fiber optic cables and punctual Pt-100 sensors. Wireless probes are also suitable to correct temperature profiles recorded with fiber optics with systematic errors of up to -0.93 K. Various boundary conditions such as the inclination of the BHE pipes or changes of the viscosity and density of the BHE fluid effect the descent rate of the GS of up to 40 %. We additionally provide recommendations for technical implementations of future measurement probes and contribute to an improved understanding and further development of WTMs.</p>

Automatic Ship Routing with High Reliability and Efficiency between Two Arbitrary Points at Sea

2018 ◽  
Vol 72 (2) ◽  
pp. 430-446
Author(s):  
Shuaidong Jia ◽  
Zeyuan Dai ◽  
Lihua Zhang
Keyword(s):  
Binary Tree ◽  
High Reliability ◽  
Spatial Database ◽  
Experimental Results ◽  
Ship Routing ◽  
Shortest Distance ◽  
Tree Index ◽  
Tree Method

Due to the limitations of the existing methods (for example, the route binary tree method) that can only automatically generate routes based on a single chart, a method for automatically generating the shortest distance route based on an obstacle spatial database is proposed. Using this proposed method, the route between two arbitrary points at sea can be automatically generated. First, the differences in accuracy and updating time of charts are quantitatively analysed. Next, the mechanism for updating obstacles is designed, an obstacle spatial database is constructed, and the obstacle data extracted from multiple charts are fused. Finally, considering the effect of efficiency on the amount of obstacle data, a route window and an improved R-tree index are designed for quickly extracting and querying the obstacle database. The experimental results demonstrate that compared with existing methods, the proposed method can generate the shortest distance between two arbitrary points at sea and eliminates the limitation of the area of the chart. In addition, with data from multiple charts, the route generated by the proposed method is more reliable than that of the existing methods, and it is more efficient.

Advanced reaction wheel controller for attitude control of spacecraft

1982 ◽  
Vol 9 (12) ◽  
pp. 697-702 ◽  
Author(s):  
K. Tsuchiya ◽  
M. Inoue ◽  
N. Wakasuqi ◽  
T. Yamaguchi
Keyword(s):  
Attitude Control ◽  
Reaction Wheel
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