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Abstract：
Dual-frequency Global Positioning System (GPS) Real-time Kinematics (RTK) has been proven in the past few years to be a reliable and efficient technique to obtain high accuracy positioning. However, there are still challenges for GPS single-frequency RTK, such as low reliability and ambiguity resolution (AR) success rate, especially in kinematic environments. Recently, multi-Global Navigation Satellite System (multi-GNSS) has been applied to enhance the RTK performance in terms of availability and reliability of AR. In order to further enhance the multi-GNSS single-frequency RTK performance in terms of reliability, continuity and accuracy, a low-cost micro-electro-mechanical system (MEMS) inertial measurement unit (IMU) is adopted in this contribution. We tightly integrate the single-frequency GPS/BeiDou/GLONASS and MEMS-IMU through the extended Kalman filter (EKF), which directly fuses the ambiguity-fixed double-differenced (DD) carrier phase observables and IMU data. A field vehicular test was carried out to evaluate the impacts of the multi-GNSS and IMU on the AR and positioning performance in different system configurations. Test results indicate that the empirical success rate of single-epoch AR for the tightly-coupled single-frequency multi-GNSS RTK/INS integration is over 99% even at an elevation cut-off angle of 40°, and the corresponding position time series is much more stable in comparison with the GPS solution. Besides, GNSS outage simulations show that continuous positioning with certain accuracy is possible due to the INS bridging capability when GNSS positioning is not available.
摘要：
在过去的几年中，双频全球定位系统（GPS）实时运动学（RTK）已被证明是获得高精度定位的可靠有效技术。然而,GPS单频RTK仍然存在挑战，例如低可靠性和歧义解决(AR)成功率，尤其是在运动学环境中。最近,多全球导航卫星系统（multi-GNSS）已被用于增强RTK在可用性和可靠性方面的性能。为了进一步提高多GNSS单频RTK在可靠性方面的性能,连续性和准确性，在此贡献中采用了低成本的微机电系统（MEMS）惯性测量单元（IMU）。我们通过扩展卡尔曼滤波器（EKF）将单频GPS/北斗/GLONASS和MEMS-IMU紧密集成，它直接融合了歧义固定的双差（DD）载波相位可观测值和IMU数据。进行了现场车辆测试，以评估多GNSS和IMU在不同系统配置下对AR和定位性能的影响。测试结果表明，即使在40°的仰角截止角下，紧耦合单频多GNSSRTK/INS集成的单历元AR的经验成功率也超过99％。与GPS解决方案相比，相应的位置时间序列更加稳定。此外,GNSS中断仿真表明，由于GNSS定位不可用时的INS桥接能力，可以实现具有一定精度的连续定位。
