The starlight navigation is considered to be one of the most important methods for spacecraft navigation. Starlight simulator system is a high-precision system with large fields of view, designed to test the starlight navigation sensor performance on the ground. A complete simulation of the system has been built. The starlight sensor testing system consists of star simulator, star scene generation computer, sensor control computer. The starlight simulator is made up of power module, light source, LCD, display circuitry, optical collimator and computer interface. LCD and optical collimator are the key display component of starlight simulator.
Laser micro-Doppler information generated by characteristic motion such as target rotation or vibration is a fingerprintlike feature of a target such as a vehicle/pedestrian. By combining with the Doppler information, it can be used for the classification and accurate identification of traffic participants. Meanwhile, optical sensor based on such technology is easy to integrate with intelligent driving platform or intelligent traffic monitoring and control platform. This paper proposes a laser Doppler and micro-Doppler composite signal simulation scheme based on vehicle vibration characteristics. Laser Doppler and micro-Doppler composite signals in a platform state simulated by a horn and a onedimensional mobile platform, and a reformed smooth pseudo-Wigner-Ville distribution analysis program is prepared for analysis. Based on this, vibration and motion information are extracted, the laser echo signals are constructed effectively, and physical simulation for composite signal of optical sensor are able to perform.
Starlight navigation technology is widely used in spacecraft. Celestial navigation is designed for star identification and confirmation of satellite attitudes in the space. Sensors of celestial navigation require hardware-in-the-loop simulation system for ground-testing. A new celestial navigation technology is based on dual-star-sensor for the sake of high accuracy and reliability. Hardware-in-the-loop simulation system for ground-testing generates two celestial scenes and projects them into the dual-star-sensors during navigation process by real-time graphics and simulation technologies according to the satellite’s orientation.
With the increase in application of celestial navigation as well as the advances in computer graphics technology, modeling and simulation of celestial background is widely used in ground-testing of celestial navigation.
Celestial navigation is designed for star identification and confirmation of satellite attitudes in the space. A new celestial navigation technology is based on dual-star-sensor for the sake of high accuracy and reliability. Two star-sensors are set on the satellite, and there is an angle between the light axis of these two star-sensors. So these two star-sensors are designed pointed to the different direction in the space.
Modeling and simulation of celestial background which is used in the ground-testing for dual-star-sensor displays two different celestial scenes during navigation process by real-time graphics technology according to the two sensors’ orientation.
The starlight navigation is considered to be one of the most important methods for spacecraft navigation. Starlight simulation system is a high-precision system with large fields of view, designed to test the starlight navigation sensor performance on the ground. A complete hardware-in-the-loop simulation of the system has been built. The starlight simulator is made up of light source, light source controller, light filter, LCD, collimator and control computer. LCD is the key display component of the system, and is installed at the focal point of the collimator. For the LCD cannot emit light itself, so light source and light source power controller is specially designed for the brightness demanded by the LCD. Light filter is designed for the dark background which is also needed in the simulation.
In order to test 2-color infrared sensors, a coupled infrared simulation system can generate radiometric outputs with wavelengths that range from less than 3 microns to more than 12 microns. There are two channels in the coupled simulation system, optically combined by a diachronic beam combiner. Each channel has an infrared blackbody, a filter, a diaphragm, and diaphragm-motors. The system is projected to the sensor under testing by a collimator. This makes it difficult to calibrate the system with only one-band thermal imager. Errors will be caused in the radiance levels measured by the narrow band thermal imager. This paper describes colorimetric temperature measurement techniques that have been developed to perform radiometric calibrations of these infrared simulation systems above. The calibration system consists of two infrared thermal imagers; one is operated at the wavelength range of MW-IR, and the other at the range of LW-IR.
Infrared resistor arrays perform a vital role in the hardware in the loop testing of infrared seekers. Infrared resistor arrays composed of large numbers of suspended resistor elements are commonly used to produce dynamic two-dimensional images of infrared radiation. Due to inconsistencies in the fabrication process of the resistor arrays, the temperature each resistor elements reaches for a given input voltage is variable and this leads to more significant radiance differences, these differences result in spatially-distributed radiance non-uniformity. Therefore, in order to obtain an available infrared image, non-uniformity correction (NUC) is necessary. In this paper, the non-uniformity characters of the infrared resistor arrays are analyzed base on measured data and then an improved sparse grid method for engineering are discussed and analyzed. First of all, the NUC camera has a strong influence on the effectiveness of the infrared resistor arrays NUC procedure. According to the actual fact and the laboratory condition, we presented an alternative method for collecting resistor arrays intended to reduce the influence causing by the NUC camera. Secondly, based on the measured non-uniformity data, we obtain the response characteristics of the infrared resistor arrays. In each gray level, we take two points or several points correction algorithm to calculate the gain data and the offset data, and then the linear look-up table is established. Finally, through MATLAB we develop the correction software, and we can obtain the driving output conveniently. The result shows that the image quality has a remarkable improvement after non-uniformity correction, the non-uniformity correction flow and algorithm preferably satisfies the requirement of the high confidence infrared imaging simulation.
The first and most essential capability a visible scene projection system must have is low background and high contrast during dynamic simulation. A complex visible scene projection system was developed to meet the above requirements. The complex visible scene projection system mainly consists of the optical fiber subsystem, LCD (Liquid Crystal Display) subsystem, multiple focal plane coupler and the collimation objective. The design and build and details of the system characterization of a prototype complex visible scene projector were summarized.
KEYWORDS: Stars, Star sensors, Computer simulations, Visualization, OpenGL, Image sensors, Space operations, Scene simulation, Computing systems, Navigation systems
The star sensor simulation system is uesed to test the star sensor performance on the ground,which is designed for star identification and spacecraft attitude determnation of the spacecraft. The computer star scene based on the astronomical star chat is generated for hardware-in-the-loop simulation of the star sensor simulation system using by openGL.
The multitarget compounding technique is key in an infrared hardware-in-the-loop simulation system. In this study, the beam-broadening theory and carefully designed experiments are presented to analyze a multitarget compounding system based on a dimpled mirror. By paraxial approximation of geometrical optics, the expression of broadened beamwidth of a dimpled-mirror two-mirror three-reflection concentric system was obtained as the function of system parameters. A multitarget compounding setup was designed and experiments were performed. Excellent matching results were achieved between the beamwidth theory and the experiments. Experimental results demonstrated that the beam-broadening theory is creditable and suitable to design the multitarget compounding system. The theory and experiments are beneficial to the future development and implementation of multitarget compounding technique.
IR projectors applied in HWIL simulations are responsible for generating a radiometric output which is similar to the
imager output for a real world targets and background in desired wavelength to the seeker under test. Projector
technologies meet more challenge as seekers performances improving. A variety of projectors has been constructed to
satisfy different use. This paper describes three projectors which include a dual-band IR extended source projector, a
MWIR Digital Micromirror Device(DMD) projector and a LWIR resistive array projector.
The high speed turbulence flow is a medium provided with high speed variety and heterogeneous, it has characteristics
of time correlation and space correlation. The detection performance of optical imaging detecting system on a flight
viechle is influenced by the high speed turbulence flow, when the light wave of a target pass through it. The
transmission theory of light wave passing through the turbulent flow field was presented in the paper, and the influence
principle about it on the imaging detection system was also analyzed. The simulation result based on the theory also
presented. Finally, a comparison the calculating result with the result by wind tunnel experimentation has been
discussed.
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