世界上最快的GNSS RTK ROVER上的问答：Leica GS18T

Dr. Xiaoguang Luo, Stefan SchauflerandBernhard Richterdiscuss the latest developments in the field of sensor fusion in GNSS and inertial measurement unit (IMU). The new Leica GS18 T GNSS RTK rover combines GNSS and IMU to automatically adjust pole tilt from plumb. Discover how this can increase productivity, extend RTK applicability and reduce human errors.

What are the current challenges of conventional RTK surveying?
需要手动水准极圆cular bubble and the phase centre position being reduced to the pole tip (by considering the antenna phase centre offset and the length of the pole), result in a number of disadvantages for the user:

• 在生产率方面，平整杆需要时间，尤其是在需要迭代重复的出现中。
• With respect to accuracy, holding the pole vertically is influenced by human errors and instrumental imperfections, such as a misadjusted bubble.
• Regarding applicability, it is not always possible to hold the pole vertically on a target point, for example, when measuring building corners.

In terms of solving the user’s problems: what are the major advantages of the Leica GS18 T?
新漫游者有几个好处：

• Free from on-site calibrations
• Immune to magnetic disturbances
• Applicable at large tilt angles
• 标题为3D可视化

这new Leica GS18 T GNSS RTK rover combines GNSS and IMU to automatically adjust pole tilt from plumb, which increases productivity, extends RTK applicability and reduces human errors. It improves the overall user experience beyond comparison.

图1 -Leica GS18 t GNSS RTK ROVER带有Leica CS20场控制器。

Leica GS18 T Rover如何回答对速度现场的不断增长的需求？
作为“世界上最快的GNSS RTK Rover”的定义是基于三个支柱的：基于IMUtilt compensationtechnique结合instantaneous RTK。这使生产率最高（准确性和可靠性 - 尤其是在地形调查中），并提供了与手动平衡杆进行测量相似的准确性。由于倾斜的补偿，无需将POL级别升级，这使生产率平均比常规GNSS RTK测量实践提高了20％。此外，GS18 T利用MEMS IMU的高速加速度和角速度实时确定极点的态度。由于这些IMU测量值不受磁场的影响，因此GS18 T不受磁干扰的影响，并且不需要任何耗时的现场校准。它开箱即用，比基于磁力计的系统更快。

Figure 2 - Leica GS18 T as the fastest GNSS RTK rover with the IMU-based tilt compensation.

这re is always the question of accessing difficult targets – such as building corners and obstructed points?
使用GS18 t这不再是一个挑战。由于基于IMU的倾斜补偿，以前无法使用GNS访问的目标，现在也可以直接用RTK来测量，即使在超过30度的较大倾斜角度上也可以直接测量。带有好处高级信号跟踪, the GS18 T is especially suitable for RTK applications where the sky is partially visible, for example, operating close to tree lines, under foliage or in urban canyons. By applying the基于IMU的倾斜补偿of the GS18 T, there is no limit to the maximum tilt angle as long as a sufficient number of GNSS satellites are tracked to be able to provide high-precision RTK solutions.大倾斜角是过去的问题。GS18 T适用于隐藏点测量值（例如，隐藏的角落或部分被停放的汽车阻塞）。

然后，这会直接影响在潜在危险的调查环境中测量的安全方面吗？
Exactly – without having to focus on levelling the pole, the user can pay more attention to his own safety. The risks of passing vehicles and operating machines are vastly reduced. In addition, attitude information is used to help users orientate themselves in the field by automatically updating the 3D visualisation of the surroundings (depending on the sensor orientation).

Figure 3 - Using the Leica GS18 T to measure building corners and obstructed points that were previously not measurable in conventional RTK surveying with a vertical pole.

It seems that you have successfully integrated two navigation sources, GNSS and INS?
航空航天行业长期存在的综合GNS/INS导航系统现已在调查应用程序中提供。这总结了成功的整合：

图4- Leica GS18 T中实现的GNSS/INS集成的示意图和简化的例证。

嘉莉GNSS和INS之间的一致性检查d out constantly to enable a robust system that can cope with extreme pole dynamics, such as hard shocks. Since no magnetometer measurements are involved in the computation of tilt-compensated positions, the GS18 T is immune to magnetic disturbances.

When directly comparing conventional RTK vs. tilt compensation RTK – have you performed tests to demonstrate the practical advantages?
为了证明使用倾斜补偿的好处，GS18 T针对在开放天空和强大的多路径条件下对Rover A进行了基准测试。在开放式测试（图12）中，在瞬时模式下交替测量了两个已知点P1和P2，持续10分钟。使用漫游者A，需要在进行瞬时测量之前精确地平整杆，这对于由于倾斜补偿而导致的GS18 T是不需要的。在10分钟内测量点的数量代表了生产力的简单指标。

图5 -RTK性能在开放天空下的基准测试，通过在瞬时模式下测量两个点10分钟（Rover A与GS18 T，极长：1.800 m）。

图6-在强大的多径环境（极长：1.800 m）中的RTK定位测试（a）带有金属立面建筑物附近的测量标记，（b）用Leica GS18 T的倾斜补偿RTK测量。

Table 1 summarises the results from the open-sky test with respect to productivity and accuracy:

表1-比较10分钟内测量点的数量以及GS18 T和ROVER A之间的RMS误差（开放天空，极长：1.800 m，瞬时测量）。

Without the need to level the pole, the GS18 T significantly reduces the time spent on a measurement, and thus increases the number of measured points by 33 per cent from 57 to 76 within a 10-minute period. In the tilt compensation case, despite the additional error from attitude determination, the 3D rms error is only 3 mm larger when compared to Rover A and amounts to 2.4 cm, which is acceptable for most topographic surveys.

表2总结了有关可用性，准确性和可靠性的结果：

表2-比较强大的多径环境（极长：1.800 m，瞬时测量），RTK固定位置的可用性，准确性和可靠性。

Using the GS18 T with tilt compensation, the availability of RTK fixed solutions increases by 15 per cent when compared to conventional RTK using Rover A. The positioning accuracy is significantly improved, on average by 50 per cent. The reliability gives the percentage that the position error is less than three times the CQ, which is slightly enhanced by up to 6 per cent for the horizontal components. Please also keep in mind that such a strong multipath environment is considered as an extreme case and is far beyond the standard conditions relevant for accuracy and reliability specifications. In addition, points closer than 10 cm to a building cannot be measured with Rover A at all since in this case it is not possible to level the pole at the target point.

Cars, power lines and buildings with structural steel – every surveyor faces these and further local magnetic disturbances on a daily basis. Does the new Leica GS18 T offer a solution to this problem?
答案很简单：除了不需要现场校准外，基于IMU的倾斜补偿比基于磁力计的方法的主要优点是对磁场干扰的免疫力。我们比较了磁干扰下的两个流浪者。查看表5中总结的RMS误差，GS18 T的2D精度比Rover B好大约2 cm，而1D精度在相似的水平上：

Table 3 - Comparison of the rms errors between GS18 T and Rover B under magnetic disturbances (parking lot, pole length: 1.800 m, 1-s static measurement).

Looking at the rms errors summarised in Table 3, the 2D accuracy of GS18 T is approximately 2 cm better than that of Rover B, whereas the 1D accuracy is at a similar level.

经过comparing the 2D errors in Fig. 7a, the GS18 T provides higher accuracy and consistency than Rover B. Moreover, the 2D CQ estimates agree with the 2D errors, reflecting the positioning accuracy in a realistic manner. Regarding the results from Rover B in Fig. 7b, the 2D CQ values are significantly larger than the 2D errors if magnetic disturbances are detected, indicating unreliable tilt-compensated solutions. In this case, the user needs to repeat the measurement or to switch to the conventional RTK mode, which decreases productivity. Under certain circumstances, for example, when measuring points at larger tilt angles, the user would not be notified by a magnetometer-based system that the displayed accuracy cannot be achieved.

图7-在磁性干扰（停车场，极长：1.800 m，1 -S静态测量）下，GS18 T和ROVER B之间的2D位置误差和CQ的比较。

包括标题为3D可视化在内的如何改善整体用户体验？
通过将传感器标准纳入3D可视化中，用户可以轻松地将自己定向在调查环境中，并迅速朝目标点转向，从而提高用户体验和生产力。

图8-标题为3D可视化的示例当用Leica GS18 t（开放天空，杆长：1.800 m）（a）导航视图，（b）朝西的视图，（c）（c）朝南的视图，（d））向东看。

Fig. 8 illustrates how the heading information helps when staking points with the GS18 T in the navigation view. If the stakeout point is more than 0.5 m away, the view shows the surroundings in the heading direction and follows the sensor from above and behind (Fig. 17a). The 3D view and stake instructions update automatically according to the current position and sensor heading, which changes from westward over southward to eastward in this example.

In your own words, how would you summarise the overall GS18 T advantages in comparison to other RTK rovers?
从用户角度来看：使用tilt compensation, instantaneous measurement provides a similar accuracy level as static RTK measurement, along with a favourable节省时间的效果。

与传统的RTK相比，带有垂直杆，倾斜的RTK显着提高生产率最多33 per cent相当大改善近建立的定位性能关于可用性和准确性。

在停车场与magnetic disturbances，基于IMU的倾斜补偿会产生更准确的位置和更现实的CQthan the magnetometer-based approach.

这基于IMUtilt-compensating RTK is applicable at大倾斜角超过30度, where a3D定位精度为2厘米is still achievable.

经过合并sensor heading into 3D visualisation在周围的环境中，用户可以轻松地将自己定向在调查环境中，从而提高生产力和用户体验。

这attitude informationof tilt-compensated RTK measurements isfully traceable，为用户自己和客户提供质量保证。

To learn more about theLeica GS18 t, please visit:www.sendai-torema.com/gs18t

高性能GNSS深入的信息signal tracking, the challenges in tilt compensation RTK and advanced signal tracking technologies, please download the white paper.