提昇微機電IMU/GNSS整合系統定位定向精度可行策略之研究

The Investigation of some Practical Strategies for Improving the Accuracy of a MEMS IMU/GNSS Integrated System

GPS/INS整合系統相較於個別系統在單獨使用之狀況下能克服個別系統之限制；並提供導航系統更佳的表現。本研究首先利用GPS航向器之輔助來提昇定位系統的精度。對於定位精度而言，航向的誤差影響是相當顯著的。水平速度的誤差會受到方位角誤差的影響，故當載體的速度越高，因為方位角誤差所導致的定位誤差會越大。本研究所提出的第二個策略為利用高採樣率之GPS接收儀，現行使用的動態GPS接收機之採樣頻率皆習慣使用1Hz。對於低成本的IMU而言，在兩個整秒之GPS更新期間之定位及定向的誤差累積量顯著高於高精度系統。故本研究的重點在於嘗試使用高採樣頻率（10Hz）之GPS接收機並評估該策略對整體動態定位定向精度之影響。 Integrated GPS/INS systems provide an enhanced navigation system that has superiorperformance in comparison with either system operating in stand-alone mode as it can overcomeeach of their limitations. In this study, the heading updates provided by the heading sensor is firstproposed to improve the accuracy of a MEMS IMU/GPS integrated system. The error of heading hasgreat influence on the positional accuracy because it multiplies with horizontal velocities. Therefore, those additional velocity errors project onto horizontal positioning errors after numerical integrationimplemented in the INS mechanization. The faster the vehicle moves, the larger the positional errors caused by the heading error. In addition, this study applies two sets of GPS receivers that haverelatively high sampling rate, 10Hz. In general ; the sampling rate of the GPS receivers used forkinematic positioning is rather limited to 1 Hz only. The positioning and attitude errors betweenconsecutive GPS updated measurements update for a MEMS IMU accumulate much moresignificantly than those of other sophisticated systems. Therefore, this study applies a set of GPSreceivers with 10Hz sampling rate to investigate the impact of measurement update frequencyprovided by GPS on the positioning and attitude accuracy with the use of a MEMS IMU/GPSintegrated system.

Integrated GPS/INS systems provide an enhanced navigation system that has superiorperformance in comparison with either system operating in stand-alone mode as it can overcomeeach of their limitations. In this study, the heading updates provided by the heading sensor is firstproposed to improve the accuracy of a MEMS IMU/GPS integrated system. The error of heading hasgreat influence on the positional accuracy because it multiplies with horizontal velocities. Therefore,those additional velocity errors project onto horizontal positioning errors after numerical integrationimplemented in the INS mechanization. The faster the vehicle moves, the larger the positional errors caused by the heading error. In addition, this study applies two sets of GPS receivers that haverelatively high sampling rate, 10Hz. In general ; the sampling rate of the GPS receivers used forkinematic positioning is rather limited to 1 Hz only. The positioning and attitude errors betweenconsecutive GPS updated measurements update for a MEMS IMU accumulate much moresignificantly than those of other sophisticated systems. Therefore, this study applies a set of GPSreceivers with 10Hz sampling rate to investigate the impact of measurement update frequencyprovided by GPS on the positioning and attitude accuracy with the use of a MEMS IMU/GPSintegrated system.