北斗/惯性深耦合接收机速度误差特性研究

Research on Velocity Error of the BDS/IMU Deeply-Coupled Receiver

关键词:  卫星导航系统  接收机  惯性测量单元  深耦合  惯性辅助

Key words:  GNSS  Receiver  IMU  Deeply coupled  Inertial aiding

摘要:

北斗/惯性深耦合接收机利用了惯性辅助和微惯性器件误差实时补偿技术，具有更好的高动态适应性与抗干扰能力。深耦合接收机中，惯性测量模块与接收机模块的信息相互利用，形成了2个闭合的误差传递通道：位置通道和速度通道。针对速度通道分析了误差传递特性。首先，考虑了三阶锁相环所实现的载波跟踪环路，在对组合滤波器进行简化的基础上，建立了速度通道的传递函数模型；然后，推导了惯性辅助误差到接收机速度误差的传递关系，分析了其误差特性；进一步将惯性辅助误差分为由惯性器件误差和由辅助信息更新率低引起的误差，分别分析了它们对接收机速度误差的贡献。分析结果表明：1)惯性辅助误差到接收机速度误差的传递模型表现为高通特性；2)由惯性器件误差所引起的速度误差，因受载波跟踪环路滤波器的作用而大大减小；3)比较而言，由辅助信息更新率低所引起的速度误差更为显著。

Abstract:

Utilizing the inertial information aiding and inertial sensor error compensating techniques, the BeiDou System (BDS) and Inertial Measurement Unit (IMU) deeply coupled receiver possesses higher dynamic adaptability and anti-jamming capability. In the deeply coupled receiver, the IMU module and the receiver module share information and aid each other, which lead to two closed error channels, the position error channel and velocity error channel. This paper gives detailed error analyses on the velocity error channel. First, considering the carrier tracking loop with a third order Phase Locked Loop (PLL), the transfer function model of the velocity error channel is built based on the simplification of the integration filter. Then, the transfer function from the inertial aiding error to the receiver's velocity error is derived and its error characteristic is ana-lyzed. Furthermore, the inertial aiding error is divided into two components, one caused by the impreciseness of the inertial devices and the other resulting from the low update rate of the aiding information. Contributes of these two components to the velocity error are analyzed respectively. Analyses results show that, 1) the transfer function from the inertial aiding error to the receiver's velocity error possesses high-pass-filtering characteristic, 2) the velocity error caused by the impreciseness of the inertial devices is restrained by the loop filter of the carrier tracking loop, 3) the error component resulting from the low update rate of the aiding information is far greater than the component caused by the impreciseness of the aiding information.