Department of Automatic Control, College of Mechatronics and Automation, National University of Defense Technology, Deya Street 109, Changsha 410073, Hunan, China.
Sensors (Basel). 2013 Jun 21;13(6):7979-99. doi: 10.3390/s130607979.
In the field of Global Navigation Satellite System (GNSS) attitude determination, the constraints usually play a critical role in resolving the unknown ambiguities quickly and correctly. Many constraints such as the baseline length, the geometry of multi-baselines and the horizontal attitude angles have been used extensively to improve the performance of ambiguity resolution. In the GNSS/Inertial Navigation System (INS) integrated attitude determination systems using low grade Inertial Measurement Unit (IMU), the initial heading parameters of the vehicle are usually worked out by the GNSS subsystem instead of by the IMU sensors independently. However, when a rotation occurs, the angle at which vehicle has turned within a short time span can be measured accurately by the IMU. This measurement will be treated as a constraint, namely the rate-gyro-integral constraint, which can aid the GNSS ambiguity resolution. We will use this constraint to filter the candidates in the ambiguity search stage. The ambiguity search space shrinks significantly with this constraint imposed during the rotation, thus it is helpful to speeding up the initialization of attitude parameters under dynamic circumstances. This paper will only study the applications of this new constraint to land vehicles. The impacts of measurement errors on the effect of this new constraint will be assessed for different grades of IMU and current average precision level of GNSS receivers. Simulations and experiments in urban areas have demonstrated the validity and efficacy of the new constraint in aiding GNSS attitude determinations.
在全球导航卫星系统 (GNSS) 姿态确定领域，约束条件通常在快速、正确地确定未知模糊度方面起着关键作用。许多约束条件，如基线长度、多基线的几何形状和水平姿态角，已被广泛用于提高模糊度确定的性能。在使用低等级惯性测量单元 (IMU) 的 GNSS/惯性导航系统 (INS) 综合姿态确定系统中，车辆的初始航向参数通常由 GNSS 子系统而不是由 IMU 传感器独立计算得出。然而，当发生旋转时，IMU 可以精确测量车辆在短时间内转过的角度。这个测量值将被视为一个约束条件，即速率陀螺积分约束条件，它可以辅助 GNSS 模糊度确定。我们将使用这个约束条件来筛选在模糊度搜索阶段的候选值。通过在旋转过程中施加这个约束条件，模糊度搜索空间会显著缩小，从而有助于加快动态情况下姿态参数的初始化。本文仅研究这种新约束条件在陆地车辆中的应用。我们将评估不同等级的 IMU 和当前 GNSS 接收机的平均精度水平对这种新约束条件的效果的影响。在城市地区进行的仿真和实验验证了这种新约束条件在辅助 GNSS 姿态确定方面的有效性和功效。
