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671.
SooYung Byeon Sung-Hoon Mok Hyunwook Woo Hyochoong Bang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(11):3632-3645
Satellite attitude determination accuracy significantly drops when sensor-fault occurs. Hence, a proper mitigation strategy to detect sensor-fault and accurately estimate corresponding fault magnitudes is mandatory for robust and accurate attitude determination. In this paper, a novel sensor-fault tolerant precise attitude estimator is proposed consisting of two stages. In the first stage, sensor-fault is detected, and the associated sensor parameter change is roughly estimated using an interacting multiple-model (IMM) approach. Subsequently, the second stage is triggered. The sensor parameter change is precisely estimated with a new sensor-parameter-augmented filter. This is defined as a selectively augmented extended Kalman filter (SAEKF) in this paper. The conventional augmented extended Kalman filter (AEKF) is computationally more expensive than the proposed SAEKF. The SAEKF augments only the sensor parameters affected by sensor-faults, not the full sensor parameters, into the state vector. This leads to a significant computational time-saving. A transition method from the first stage to the second stage is also investigated. Numerical simulation results demonstrate that the proposed two-stage approach has smaller attitude determination errors than the existing algorithms, ranged from 21.7% to 88.8%, in cases with gyro scale factor error or misalignment. 相似文献
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Autonomous orbit determination via integration of epoch-differenced gravity gradients and starlight refraction is proposed in this paper for low-Earth-orbiting satellites operating in GPS-denied environments.Starlight refraction compensates for the significant along-track position error that occurs from only using gravity gradients and benefits from integration in terms of improved accuracy in radial and cross-track position estimates.The between-epoch differencing of gravity gradients is employed to eliminate slowly varying measurement biases and noise near the orbit revolution frequency.The refraction angle measurements are directly used and its Jacobian matrix derived from an implicit observation equation.An information fusion filter based on a sequential extended Kalman filter is developed for the orbit determination.Truth-model simulations are used to test the performance of the algorithm,and the effects of differencing intervals and orbital heights are analyzed.A semi-simulation study using actual gravity gradient data from the Gravity field and steady-state Ocean Circulation Explorer (GOCE) combined with simulated starlight refraction measurements is further conducted,and a three-dimensional position accuracy of better than 100 m is achieved. 相似文献
673.
分析了深空通信中高动态微弱信号载波跟踪方法,提出并分析了载波跟踪中状态方程非线性与量测方程的非线性取舍问题,分析了滤波过程中影响高动态与低信噪比的决定因素,给出了两个推论,提出了强跟踪算法的必要性。并以此选择了以传统卡尔曼滤波(KF)为基础,以锁相环(FLL)、无迹卡尔曼滤波(UKF)为辅助使用两种工作模式来应对不同环境。针对组合跟踪环路状态转换过渡易出现的频率阶跃问题,给出新型环路的工作模式及切换门限的数学表达式,在环路中添加计算判别器,实时控制环路输出的同时不浪费计算力地剔除了野值,提高了环路稳定性。仿真表明,该新型环路算法与现有的算法相比有很好的低信噪高动态适应能力,消除了切换峰值,剔除了野值。 相似文献
674.
Omar Ben Bahri Kamel Besbes 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(6):1501-1511
Space technology plays a pivotal role in society development. It offers new methods for telemetry, monitoring and control. However, this sector requires training, research and skills development but the lack of instruments, materials and budgets affects the ambiguity to understand satellite technology. The objective of this paper is to describe a demonstration prototype of a smart phone device for space operations study. Therefore, the first task was carried out to give a demonstration for spatial imagery and attitude determination missions through a wireless communication. The smart phone’s Bluetooth was used to achieve this goal inclusive of a new method to enable real time transmission. In addition, an algorithm around a quaternion based Kalman filter was included in order to detect the reliability of the prototype's orientation. The second task was carried out to provide a demonstration for the attitude control mission using the smart phone’s orientation sensor, including a new method for an autonomous guided mode. As a result, the acquisition platform showed real time measurement with good accuracy for orientation detection and image transmission. In addition, the prototype kept the balance during the demonstration based on the attitude control method. 相似文献
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基于四元数非线性误差模型的快速传递对准(英文) 总被引:1,自引:0,他引:1
基于小角度假设的常规线性误差模型不能适用于大失准角时的初始对准,针对这一问题研究了一种没有小失准角假设,以速度误差和姿态四元数误差作为量测的非线性快速传递对准误差模型,并证明当误差变为小角度时,该非线性误差模型可以简化为常规线性误差模型。使用 Unscented 卡尔曼滤波代替通常采用的扩展卡尔曼滤波来处理非线性数据融合问题。为了评估和分析该非线性误差模型,设计了一个传递对准仿真系统,仿真结果表明,当初始失准角为小角度时,该新模型和线性模型有着相当的对准性能,但是当初始失准角为大角度时,本文提出的非线性误差模型仍然能够精确完成对准过程,而基于线性误差模型的对准滤波器却发散了。 相似文献
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文章针对超宽带通信技术快速发展的需要,设计了一个Chirp超宽带数字接收机。该接收机使用数字匹配滤波器避免了模拟滤波器带来的巨大插入损耗,并可以使用较为简单的方法实现时间同步。在硬件实现上,利用单比特量化匹配滤波器系数降低接收机的资源占用。实验表明该接收机结构简单、资源占用少、性能较好。 相似文献