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1.
A new approach for airborne vector gravimetry using GPS/INS 总被引:2,自引:2,他引:2
A new method for airborne vector gravimetry using GPS/INS has been developed and the results are presented. The new algorithm
uses kinematic accelerations as updates instead of positions or velocities, and all calculations are performed in the inertial
frame. Therefore, it is conceptually simpler, easier, more straightforward and computationally less expensive compared to
the traditional approach in which the complex navigation equations should be integrated. Moreover, it is a unified approach
for determining all three vector components, and no stochastic gravity modeling is required. This approach is based on analyzing
the residuals from the Kalman filter of sensor errors, and further processing with wavenumber coefficient filterings is applied
in case closely parallel tracks of data are available. An application to actual test-flight data is performed to test the
validity of the new algorithm. The results yield an accuracy in the down component of about 3–4 mGal. Also, comparable results
are obtained for the horizontal components with accuracies of about 6 mGal. The gravity modeling issue is discussed and alternative
methods are presented, none of which improves on the original approach.
Received: 18 April 2000 / Accepted: 14 August 2000 相似文献
2.
Flight test results from a strapdown airborne gravity system 总被引:3,自引:0,他引:3
In June 1995, a flight test was carried out over the Rocky Mountains to assess the accuracy of airborne gravity for geoid
determination. The gravity system consisted of a strapdown inertial navigation system (INS), two GPS receivers with zero baseline
on the airplane and multiple GPS master stations on the ground, and a data logging system. To the best of our knowledge, this
was the first time that a strapdown INS has been used for airborne gravimetry. The test was designed to assess repeatability
as well as accuracy of airborne gravimetry in a highly variable gravity field. An east-west profile of 250 km across the Rocky
Mountains was chosen and four flights over the same ground track were made. The flying altitude was about 5.5km, i.e., between
2.5 and 5.0km above ground, and the average flying speed was about 430km/h. This corresponds to a spatial resolution (half
wavelength of cutoff frequency) of 5.07.0km when using filter lengths between 90 and 120s. This resolution is sufficient for
geoid determination, but may not satisfy other applications of airborne gravimetry. The evaluation of the internal and external
accuracy is based on repeated flights and comparison with upward continued ground gravity using a detailed terrain model.
Gravity results from repeated flight lines show that the standard deviation between flights is about 2mGal for a single profile
and a filter length of 120s, and about 3mGal for a filter length of 90s. The standard deviation of the difference between
airborne gravity upward continued ground gravity is about 3mGal for both filter lengths. A critical discussion of these results
and how they relate to the different transfer functions applied, is given in the paper. Two different mathematical approaches
to airborne scalar gravimetry are applied and compared, namely strapdown inertial scalar gravimetry (SISG) and rotation invariant
scalar gravimetry (RISG). Results show a significantly better performance of the SISG approach for a strapdown INS of this
accuracy class. Because of major differences in the error model of the two approaches, the RISG method can be used as an effective
reliability check of the SISG method. A spectral analysis of the residual errors of the flight profiles indicates that a relative
geoid accuracy of 23cm over distances of 200km (0.1 ppm) can be achieved by this method. Since these results present a first
data analysis, it is expected that further improvements are possible as more refined modelling is applied.
Received: 19 August 1996 / Accepted: 12 May 1997 相似文献
3.
重力辅助惯性导航系统GAINS(Gravity Aided Inertial Navigation System)是利用地球物理特征信息──重力来完成水下运动载体的辅助惯性导航与定位。为实现重力匹配以校正惯性导航随时间累积的误差,首先必须对重力传感器输出信息进行扰动改正。分析了水下运动状态下重力传感器受到的各种重力扰动,如垂直扰动加速度、水平扰动加速度以及厄特弗斯效应影响所产生的原因,研究了扰动误差模型与INS导航精度之间的关系,并通过计算,提出了可直接以INS输出数据而无需其它外部有源导航信息进行扰动分离的方法。 相似文献
4.
GAINS中重力传感器信息的扰动改正 总被引:5,自引:0,他引:5
重力辅助惯性导航系统GAINS(Gravity Aided Inertial Navigation System)是利用地球物理特征信息重力来完成水下运动载体的辅助惯性导航与定位.为实现重力匹配以校正惯性导航随时间累积的误差,首先必须对重力传感器输出信息进行扰动改正.分析了水下运动状态下重力传感器受到的各种重力扰动,如垂直扰动加速度、水平扰动加速度以及厄特弗斯效应影响所产生的原因,研究了扰动误差模型与INS导航精度之间的关系,并通过计算,提出了可直接以INS输出数据而无需其它外部有源导航信息进行扰动分离的方法. 相似文献
5.
Xiaopeng Li 《Journal of Geodesy》2011,85(9):597-605
Combining data from a Strapdown Inertial Navigation System and a Differential Global Positioning System (SINS/DGPS) has shown
great promise in estimating gravity on moving platforms. Previous studies on a ground-vehicle system obtained 1–3 mGal precision
with 2 km spatial resolution. High-accuracy Inertial Measurement Units (IMU) and cm-level positioning solutions are very important
in obtaining mGal-level gravity disturbance estimates. However, these ideal configurations are not always available or achievable.
Because the noise level in the SINS/DGPS gravimetric system generally decreases with an increase of speed and altitude of
the platform, the stringent constraints on the IMU and GPS may be relieved in the airborne scenario. This paper presents an
investigation of one navigation-grade and one tactical-grade IMU for the possibility of low-cost INS/GPS airborne gravimetry.
We use the data collected during the Gravity-Lidar Study of 2006 (GLS06), which contains aerogravity, GPS, and INS along the
northern coastline of the Gulf of Mexico. The gravity disturbance estimates from the navigation-grade IMU show 0.5–3.2 mGal
precision compared with the onboard gravimeter’s measurements and better than 3 mGal precision compared with the upward continued
surface control data. Due to relatively large (240 s) smoothing window, the results have about 34 km along-track resolution.
But the gravity estimates from the tactical-grade IMU have much poorer precisions. Nonetheless, useful contributions from
the tactical-grade IMU could be extracted for longer wavelengths. 相似文献
6.
飞机运动加速度的测量精度是制约航空重力测量技术发展的主要障碍之一。相较于传统动态差分GPS(differential GPS,DGPS)技术,所提方法采用单站测量模式,无需布设地面基准站。首先通过相位历元间差分解得高精度历元间位移序列,然后结合泰勒一阶中心差分获得载体加速度,重点分析了卫星轨道和卫星钟差对加速度估计的影响,结果表明,不同卫星轨道产品对加速度估计影响较小,而卫星钟差采样率对加速度估计的影响很大。结合中国陕西省境内的GT-2A航空重力测量系统飞行实测数据,利用单站法解算的加速度联合重力和姿态数据解算重力扰动结果与DGPS解算的重力扰动符合较好,当滤波长度为100 s时,两者互差优于1.0 mGal。重力扰动交叉点不符值网平差后,均方根(root mean square,RMS)为1.13 mGal。与地面重力实测值比较的结果表明,所提方法与DGPS方法在精度上基本一致,说明单站法标量航空重力测量是可行的。 相似文献
7.
A comparison of stable platform and strapdown airborne gravity 总被引:3,自引:1,他引:2
C. L. Glennie K. P. Schwarz A. M. Bruton R. Forsberg A. V. Olesen K. Keller 《Journal of Geodesy》2000,74(5):383-389
To date, operational airborne gravity results have been obtained using either a damped two-axis stable platform gravimeter
system such as the LaCoste and Romberg (LCR) S-model marine gravimeter or a strapdown inertial navigation system (INS), showing
comparable accuracies. In June 1998 three flight tests were undertaken which tested an LCR gravimeter and a strapdown INS
gravity system side by side. To the authors' knowledge, this was the first time such a comparison flight was undertaken. The
flights occurred in Disko Bay, off the west coast of Greenland. Several of the flight lines were partly flown along existing
shipborne gravity profiles to allow for an independent source of comparison of the results. The results and analysis of these
flight tests are presented. The measurement method and error models for both the stable platform and strapdown INS gravity
systems are presented and contrasted. An intercomparison of gravity estimates from both systems is given, along with a comparison
of the individual estimates with existing shipborne gravity profiles. The results of the flight tests show that the gravity
estimates from the two systems agree at the 2–3 mGal level, after the removal of a linear bias. This is near the combined
noise level of the two systems. It appears that a combination of both systems would provide an ideal airborne gravity survey
system, combining the excellent bias stability of the LCR gravimeter with the higher dynamic range and increased spatial resolution
of the strapdown INS.
Received: 3 June 1999 / Accepted: 30 November 1999 相似文献
8.
Christopher Jekeli 《Journal of Geodesy》1994,69(1):1-11
Vector gravimetry using a precise inertial navigation system continually updated with external position data, for example using GPS, is studied with respect to two problems. The first concerns the attitude accuracy requirement for horizontal gravity component estimation. With covariance analyses in the space and frequency domains it is argued that with relatively stable uncompensated gyro drift, the short-wavelength gravity vector can be estimated without the aid of external attitude updates. The second problem concerns the state-space estimation of the gravity signal where considerable approximations must be assumed in the gravity model in order to take advantage of the ensemble error estimation afforded by the Kalman filter technique. Gauss-Markov models for the gravity field are specially designed to reflect the attenuation of the signal at a specific altitude and the omission of the long-wavelength components from the estimation. With medium accuracy INS/GPS systems, the horizontal components of gravity with wavelengths shorter than 250 km should be estimable to an accuracy of 4–6 mgal (µg); while high accuracy systems should yield an improvement to 1–2 mgal. 相似文献
9.
Comparing the Kalman filter with a Monte Carlo-based artificial neural network in the INS/GPS vector gravimetric system 总被引:4,自引:1,他引:3
X. Li 《Journal of Geodesy》2009,83(9):797-804
Rigorous physical and mathematical analysis has been intensively developed to obtain the gravity disturbance vector from the
inertial navigation system and the global positioning system. However, the combination of the observation noise and the systematic
INS errors make it very challenging to accurately and efficiently describe the dynamics of the system with rigorous equations.
Thus, the accuracy of the gravity disturbance estimates, especially in the horizontal components, is limited by the insufficient
error models. To overcome the difficulty of directly modeling the systematic errors with exact mathematical equations, a Monte
Carlo based artificial neural network is successfully applied in the moving base gravimetric system. The computation results
show significant improvement in the precision of all components of the gravity disturbance estimates. 相似文献
10.
A comparison and analysis of airborne gravimetry results from two strapdown inertial/DGPS systems 总被引:2,自引:0,他引:2
In September 1996 the University of Calgary tested a combination of strapdown inertial navigation systems and differential
global positioning system (DGPS) receivers for their suitability to determine gravity at aircraft flying altitudes. The purpose
of this test was to investigate the long-term accuracy and repeatability of the system, as well as its potential for geoid
and vertical gradient of gravity determination. The test took place during a 3-day period in the Canadian Rocky Mountains
over a single 100 × 100 km area which was flown with 10-km line spacing. Two flights were done at 4350 m in E–W and N–S profile
directions, respectively, and one at 7300 m with E–W profiles. Two strapdown inertial systems, the Honeywell LASEREF III and
the Litton-101 Flagship, were flown side by side. Comparison of the system estimates with an upward-continued reference showed
root-mean-square (RMS) agreement at the level of 3.5 mGal for 90- and 120-s filter lengths. The LASEREF III, however, performed
significantly better than the Litton 101 for shorter filtering periods of 30 and 60 s. A comparison between the two systems
results in an RMS agreement of 2.8 and 2.3 mGal for the 90- and 120-s filters. The better agreement between the two systems
is mainly due to the fact that the upward-continued reference has not been filtered identically to the system gravity disturbance
estimates. Additional low-frequency differences seem to point to an error in the upward-continued reference. Finally, an analysis
of crossover points between flight days for the LASEREF III shows a standard deviation of 1.6 mGal, which is near the noise
level of the INS and GPS data. Further improvements to the system are possible, and some ideas for future work are briefly
presented.
Received: 17 March 1998 / Accepted: 1 February 1999 相似文献
11.
GPS phase accelerations for moving-base vector gravimetry 总被引:6,自引:1,他引:6
For airborne gravimetry using INS and GPS, the accelerations from both systems are differenced to yield the gravity acceleration.
Usually, the GPS acceleration is determined by first solving for the position of the vehicle relative to a base station and
subsequently taking two time derivatives of the vertical component. An alternative method is to time-differentiate the observed
phases directly, thus avoiding the cycle ambiguity problem that must be solved for positioning and that is fraught with (certainly
not insurmountable) difficulties in the event of a cycle slip. Due to the largely unpredictable receiver-clock errors and
the imposition of the Selective Availability degradation, doubly differenced (in space) phase accelerations are used to obtain
the relative vehicle accelerations. Test results for stationary receivers show that the acceleration vector can be determined
from phase accelerations to an accuracy of 1 mgal for 40-s averages. The mathematical formulation of the acceleration determination
also highlights certain other advantages over traditional methods, such as the avoidance of the E?tv?s correction, although
a similar kind of velocity effect must be determined.
Received: 9 September 1996 / Accepted: 14 April 1997 相似文献
12.
Christopher Jekeli 《Journal of Geodesy》1992,66(1):54-61
The Global Positioning System (GPS) is considered in conjunction with a strapdown Inertial Measurement Unit (IMU) for measuring the gravity vector. A comparison of this system in space and on an airborne platform shows the relative importance of each system element in these two different acceleration environments. With currently available instrumentation, the acceleration measurement accuracy is the deciding factor in space, while on an Earth-bound (including airborne) platform, the attitude error of the IMU is most critical. A simulation shows that GPS-derived accelerations in space can be accurate to better than 0.1mgal for a 30s integration time, leading to estimates of 1° mean gravity anomalies on the Earth's surface with an accuracy of 4–5 mgal. On an airborne platform, the horizontal gravity estimation error is tightly coupled to the attitude error of the platform, which can only be bounded by external attitude updates. Horizontal gravity errors of 5mgal are achievable if the attitude is maintained to an accuracy of 1arcsec. 相似文献
13.
研究了不同运动状态下扰动重力水平分量(HDG)对高精度惯导系统(inertial navigation system,INS)的位置误差影响。首先推导了HDG对INS误差影响的状态空间方程,进而推导出3种运动条件下INS位置误差与HDG之间的解析关系式,设计了基于惯导解算求解上述影响的方法。在匀速运动条件下,分别通过解析式与惯导解算两种方法计算了相同HDG引起的INS位置误差。解析式计算结果表明,±80 mGal(1 mGal=10-5 m/s2)范围内变化的HDG约可引起最大约3 000 m的INS位置误差;对两种方法计算结果的比较显示,所得INS位置误差的量级与变化情况基本一致,两组结果验证了各自方法的有效性。 相似文献
14.
Local geoid determination from airborne vector gravimetry 总被引:3,自引:2,他引:1
Methods are illustrated to compute the local geoid using the vertical and horizontal components of the gravity disturbance vector derived from an airborne GPS/inertial navigation system. The data were collected by the University of Calgary in a test area of the Canadian Rocky Mountains and consist of multiple parallel tracks and two crossing tracks of accelerometer and gyro measurements, as well as precise GPS positions. Both the boundary-value problem approach (Hotines integral) and the profiling approach (line integral) were applied to compute the disturbing potential at flight altitude. Cross-over adjustments with minimal control were investigated and utilized to remove error biases and trends in the estimated gravity disturbance components. Final estimation of the geoid from the vertical gravity disturbance included downward continuation of the disturbing potential with correction for intervening terrain masses. A comparison of geoid estimates to the Canadian Geoid 2000 (CGG2000) yielded an average standard deviation per track of 14 cm if they were derived from the vertical gravity disturbance (minimally controlled with a cross-over adjustment), and 10 cm if derived from the horizontal components (minimally controlled in part with a simulated cross-over adjustment). Downward continuation improved the estimates slightly by decreasing the average standard deviation by about 0.5 cm. The application of a wave correlation filter to both types of geoid estimates yielded significant improvement by decreasing the average standard deviation per track to 7.6 cm. 相似文献
15.
GPS单点测速的误差分析及精度评价 总被引:6,自引:0,他引:6
首先从理论和实测数据模拟两方面分析了SA取消后各类误差源对GPS测速的影响,推导并计算了GPS单点测速可能达到的精度水平。然后用静态数据模拟动态测速试验和实测动态数据测速与同步高精度惯导测速的动态试验进行验证。结果表明,采用载波相位导出的多普勒观测值使用静态数据模拟动态测速,其精度可以达到mm/s级;用接收机输出的多普勒观测值进行测速时,其精度为cm/s级。在动态测速试验中,GPS单点测速方法(即多普勒观测值测速与导出多普勒观测值测速)间的符合精度达到cm/s级,与高精度的惯导测速结果的符合精度为dm/s级,而且和运动载体的动态条件(如加速度和加速度变化率的大小)具有很强的相关性。 相似文献
16.
A combined algorithm of improving INS error modeling and sensor measurements for accurate INS/GPS navigation 总被引:1,自引:1,他引:1
Although the integrated system of a differential global positioning system (DGPS) and an inertial navigation system (INS)
had been widely used in many geodetic navigation applications, it has sometimes a major limitation. This limitation is associated
with the frequent occurrence of DGPS outages caused by GPS signal blockages in certain situations (urban areas, high trees,
tunnels, etc.). In the standard mechanization of INS/DGPS navigation, the DGPS is used for positioning while the INS is used
for attitude determination. In case of GPS signal blockages, positioning is provided using the INS instead of the GPS until
satellite signals are obtained again with sufficient accuracy. Since the INS has a very short-time accuracy, the accuracy
of the provided INS navigation parameters during these periods decreases with time. However, the obtained accuracy in these
cases is totally dependent on the INS error model and on the quality of the INS sensor data. Therefore, enhanced navigation
parameters could be obtained during DGPS outages if better inertial error models are implemented and better quality inertial
measurements are used. In this paper, it will be shown that better INS error models are obtained using autoregressive processes
for modeling inertial sensor errors instead of Gauss–Markov processes that are implemented in most of the current inertial
systems and, on the other hand, that the quality of inertial data is improved using wavelet multi-resolution techniques. The
above two methods are discussed and then a combined algorithm of both techniques is applied. The performance of each method
as well as of the combined algorithm is analyzed using land-vehicle INS/DGPS data with induced DGPS outage periods. In addition
to the considerable navigation accuracy improvement obtained from each single method, the results showed that the combined
algorithm is better than both methods by more than 30%. 相似文献
17.
分别采用基于梯度、基于泊松积分和基于快速傅里叶变换(FFT)的地面重力向上延拓方案,并提出交叉检验方法估计地面重力数据误差及其空中误差传播,对毛乌素测区GT-2A航空重力测量系统采集的空中测线数据进行外符合精度评价。对比结果表明:地面重力格网插值误差和代表性误差对空中点的影响达到0.66~0.92 mGal(1 Gal=1×10-2 m/s2),航空重力数据误差估计必须扣除这一影响;基于泊松积分和基于FFT的地面重力向上延拓方法能够客观评价航空重力观测值的外符合精度,二者表现相当;扣除地面重力误差影响后,在包含残余边界效应的情况下,毛乌素测区GT-2A航空重力空中测线重力扰动的外符合精度优于1.42 mGal。 相似文献
18.
Any errors in digital elevation models (DEMs) will introduce errors directly in gravity anomalies and geoid models when used
in interpolating Bouguer gravity anomalies. Errors are also propagated into the geoid model by the topographic and downward
continuation (DWC) corrections in the application of Stokes’s formula. The effects of these errors are assessed by the evaluation
of the absolute accuracy of nine independent DEMs for the Iran region. It is shown that the improvement in using the high-resolution
Shuttle Radar Topography Mission (SRTM) data versus previously available DEMs in gridding of gravity anomalies, terrain corrections
and DWC effects for the geoid model are significant. Based on the Iranian GPS/levelling network data, we estimate the absolute
vertical accuracy of the SRTM in Iran to be 6.5 m, which is much better than the estimated global accuracy of the SRTM (say
16 m). Hence, this DEM has a comparable accuracy to a current photogrammetric high-resolution DEM of Iran under development.
We also found very large differences between the GLOBE and SRTM models on the range of −750 to 550 m. This difference causes
an error in the range of −160 to 140 mGal in interpolating surface gravity anomalies and −60 to 60 mGal in simple Bouguer
anomaly correction terms. In the view of geoid heights, we found large differences between the use of GLOBE and SRTM DEMs,
in the range of −1.1 to 1 m for the study area. The terrain correction of the geoid model at selected GPS/levelling points
only differs by 3 cm for these two DEMs. 相似文献
19.
Accurate estimates of the velocity and acceleration of a platform are often needed in high dynamic positioning, airborne gravimetry,
and geophysics. In turn, differentiation of GPS signals is a crucial process for obtaining these estimates. It is important
in the measurement domain where, for example, the phase measurements are used along with their instantaneous derivative (Doppler)
to estimate position and velocity. It is also important in postprocessing, where acceleration is usually estimated by differentiating
estimates of position and velocity. Various methods of differentiating a signal can have very different effects on the resulting
derivative, and their suitability varies from situation to situation. These comments set the stage for the investigations
in this article. The objective is twofold: (1) to carry out a comprehensive study of possible differentiation methods, characterizing
each in the frequency domain; and (2) to use real data to demonstrate each of these methods in both of the measurement and
position domains, in conditions of variable, high, or unknown dynamics. Examples are given using real GPS data in both the
measurement domain and in the position and velocity domain. The appropriate differentiator is used in several cases of varying
dynamics to derive a Doppler signal from carrier phase measurements (rather than using the raw Doppler generated by the receiver).
In the statistic case, it is seen that the accuracy of velocity estimates can be improved from 4.0 mm/s to 0.7 mm/s by using
the correct filter. In conditions of medium dynamics experienced in an airborne gravity survey, it is demonstrated that accelerations
as the 2–4 mGal level (1 mGal = 0.00001 m/s2) can be obtained at the required filtering periods. Finally, a precision motion table is used to show that when using the
correct filter, velocity estimates under high dynamics can be improved by an order of magnitude to 27.0 mm/s. ? 1999 John
Wiley & Sons, Inc. 相似文献
20.
SUN Zhongmiao XIA Zheren LI Yingchun 《地球空间信息科学学报》2007,10(3):163-167
Abstract The cross-coupling corrections for the LaCoste & Romberg airborne gravimeter are computed as a linear combination of 5 so-called cross-coupling monitors. The weight factors (coefficients) determined from marine gravity data by the factory are obviously not optimal for airborne application. These coefficients are recalibrated by minimizing the difference between airborne data and upward continued surface data (external calibration) and by minimizing the errors at line crossings (internal calibration) respectively. An integrating method to recalibrate the above-mentioned coefficients and the beam scale factor simultaneously is also presented. Experimental results show that the systemic errors in the airborne gravity anomalies can be greatly reduced by using any of the recalibrated coefficients. For example, the systemic error is reduced from 4.8 mGal to 1.8 mGal in Datong test. 相似文献