摘要：With research on the carrier phase synchronization and symbol synchronization algorithm of demodulation module, a synchronization circuit system is designed for GPS software receiver based on field programmable gate array （FPGA）, and a series of experiment is done on the hardware platform. The result shows the all-digital synchronization and demodulation of GPS intermediate frequency （IF） signal can be realized and applied in embedded real-time GPS software receiver system. It is verified that the decision-directed joint tracking algorithm of carrier phase and symbol timing for received signals from GPS is reasonable. In addition, the loop works steadily and can be used for receiving GPS signals using synchronous demodulation. The synchronization circuit for GPS software receiver designed based on FPGA has the features of low cost, miniaturization, low power and real-time. Surely, it will become one of the development directions for GPS and even GNSS embedded real-time software receiver.

摘要：提出了一类近圆回归轨道的设计方法,解决当飞行任务对星下点有要求时,近圆回归轨道的设计问题。分析了星下点轨迹与轨道参数的关系,概括为当对星下点轨迹有要求时,近圆回归轨道的设计依赖于轨道半径和轨道倾角两个参数的确定。以轨道半径和轨道倾角为未知量依据星下点轨迹要求条件构建了非线性方程组,但直接求解过于复杂,采取迭代的方法解决。编制了MATLAB程序进行设计计算,并将计算结果用软件STK(Satellite Tool Kit)进行仿真。仿真结果显示,该算法能够较好的实现设计目标。

摘要：针对多传感器组合导航系统对数据通讯的同步性和实时性的要求,以单片机和DSP双CPU导航计算机构成的嵌入式导航系统为对象,开展了相应的接口子系统设计和实现研究。完成了组合导航计算机的接口电路,并以此为基础,设计了整个导航接口子系统的时序控制流程,以实现多传感器数据采集的同步性和实时性。同时给出了数据采集周期和导航解算周期的时序控制,以及双CPU之间的实时数据通讯的实现流程,最后通过实物联调验证了该方案设计的可行性。

摘要：The strapdown inertial navigation system （SINS）/two-antenna GPS integrated navigation system is discussed. Corresponding error and the measurement models are built, especially the double differenced GPS carrier phase model. The extended Kalman filtering is proposed. And the hardware composition and connection are designed to simulate the SINS/two-antenna GPS integrated navigation system. Results show that the performances of the system, the precision of the navigation and the positioning, the reliability and the practicability are im proved.

摘要：针对姿态误差对天文观测角度量测的影响,提出结合天文观测角度量测的机载惯性/天文深度组合算法。在位置误差小角度关系分析的基础上,进一步分析惯导姿态误差引入的计算地理水平坐标系与当地地理坐标系之间的姿态误差小角度关系,推导并建立基于天文高度角和方位角量测的深组合惯性/天文量测方程,针对天文观测量测对高度通道不可观,增加气压高度为量测量,设计相应组合滤波方法。该方法充分考虑了姿态误差对于天文观测的影响,仿真验证表明所设计方案可以有效消除惯导系统陀螺累积误差,提高惯导系统的姿态精度,验证了其可行性。

摘要：分析了MEMS微惯性姿态系统温度及载体运动等环境因素对MEMS惯性传感器的影响和姿态系统的关键技术;针对MEMS惯性器件的热环境优化,建立了基于有限元分析方法的热分析模型,仿真分析了散热设计方案,基于微惯性姿态系统样机,试验验证了散热设计的有效性;针对MEMS惯性传感器误差的强非线性特性,建立了全温范围分段线性误差补偿模型,改进了误差标定方法,有效提高了MEMS惯性器件的精度;分析了微惯性姿态组合算法的适用性条件,优化设计了基于载体飞行状态的微惯性姿态系统姿态滤波的约束条件。转台试验和飞行试验充分验证了环境适应性优化设计方法和结果的有效性,全程飞行条件下姿态误差优于2.5°,稳定飞行阶段姿态误差优于1°,该系统可满足姿态备份和微小型无人飞行器的应用需求。

摘要：本文探讨了如何利用惯性测量组合本身的信息来提高捷联航姿系统的姿态精度。根据平台式阻尼网络的思想,设计了捷联式内阻尼卡尔曼滤波器,将惯导系统捷联解算获得的姿态与加速度计估计的姿态进行组合,在系统非加速度状态下,提高了姿态输出的精度。为了实时监测系统的运动状态从而判断内阻尼姿态的有效性,本文成功将状态x^2检验法应用在内阻尼卡尔曼滤波器中,设计了基于2个状态传播器的故障监测器,并通过对故障检测向量元素的检验代替对整个向量的检验,提高了故障监测的灵敏度和可靠性。最后,实际系统的动静态实验验证了本文所提出的方法的有效性。

摘要：The principle of the inertial navigation system（INS） with rotating inertial measurement unit （IMU） is analyzed. A new IMU is established to rotate round each axis in three directions. Then, the related error models for the designed system during rotating are deduced and the improved system is built. Finally, the performance simulation of the proposed system is provided. The simulation result indicates that the designed system can improve the accuracy of the roll and the pitch as well as heading by rotating three axes, thus guaranting the heading accuracy. Moreover, based on the principle of rotation at six different positions, such structure can carry out real-time calibration, and improve the system performance.

摘要：多传感器组合是提高导航系统定位精度和增强系统容错性的有效手段。在分析惯性、星光、卫星导航工作特性的基础上,提出了基于集中滤波器结构的捷联惯性/星光/卫星信息融合导航方案。针对多传感器信息融合中非等间隔量测特性,设计了时间更新和量测更新分离的异步集中卡尔曼滤波算法,设计了基于外推法的卫星信息补偿算法,有效解决了多传感器非等间隔信息融合问题;针对垂直机动研究了惯性/星光姿态组合模型。仿真结果表明,算法可以有效实现对捷联惯导、星光、卫星导航信息的融合,组合精度提高1倍,具有重要的实际应用价值。

摘要：针对微小型应用场合,设计了基于DSP的导航计算机,成功构建了低成本小型捷联航姿系统。重点描述了DSP导航计算机的硬件设计思路,特别是“数字信号处理器(DSP)+单片机(MCU)”的特殊的主从式双CPU结构。扼要介绍了系统软件的框架结构。实验表明:基于DSP的捷联惯性航姿系统,性能稳定、达到了设计精度,降低了成本,成功的实现了系统的小型化。导航计算机体积仅为65×80×10,对导航系统在小型化领域推广应用具有实际意义。