Rate calibration and six position calibration tests are discussed about a kind of micro inertial ... more Rate calibration and six position calibration tests are discussed about a kind of micro inertial measurement unit (MIMU). A simple mathematical model of micro gyroscope and accelerometer is designed, some model parameters such as bias, scale factor, cross-axis coupling factors etc are confirmed. The effect of the model compensation is checked by the real tests. The tests result shows that gyroscope drift error compensated is near 0.01o/s, the accelerometer error is below 10 -3 g, the precision of MIMU is highly improved after error compensation, and the mathematical model is simple and the speed of calculation is also high.
The basic idea of intelligent transport systems(ITS) is introduced in this paper. GPS/INU/DM inte... more The basic idea of intelligent transport systems(ITS) is introduced in this paper. GPS/INU/DM integrated navigation location technology and its application in ITS are described. In addition, several technical measures to increase integrated navigation location precision and reliability are presented. This technology combines satellite navigation, inertial navigation with information technologies, and has all direction, 24 hours standby and non shadowed characteristics. The ‘automation’ of transportation management and the ‘intelligence’ of vehicular driving will be realized through using of integrated navigation location technology. Integrated navigation location technology has better practicing value and widely prospect.
ABSTRACT Noise in topographic data obscures features and increases error in geomorphic products c... more ABSTRACT Noise in topographic data obscures features and increases error in geomorphic products calculated from DEMs. DEMs produced by radar remote sensing, such as SRTM, are frequently used for geomorphological studies, they often contain speckle noise which may significantly lower the quality of geomorphometric analyses. We introduce here an algorithm that denoises three-dimensional objects while preserving sharp features. It is free to download and simple to use. In this study the algorithm is applied to topographic data (synthetic landscapes, SRTM, TOPSAR) and the results are compared against using a mean filter, using LiDAR data as ground truth for the natural datasets. The level of denoising is controlled by two parameters: the threshold (T) that controls the sharpness of the features to be preserved, and the number of iterations (n) that controls how much the data are changed. The optimum settings depend on the nature of the topography and of the noise to be removed, but are typically in the range T = 0.87–0.99 and n = 1–10. If the threshold is too high, noise is preserved. A lower threshold setting is used where noise is spatially uncorrelated (e.g. TOPSAR), whereas in some other datasets (e.g. SRTM), where filtering of the data during processing has introduced spatial correlation to the noise, higher thresholds can be used. Compared to those filtered to an equivalent level with a mean filter, data smoothed by the denoising algorithm of Sun et al. [Sun, X., Rosin, P.L., Martin, R.R., Langbein, F.C., 2007. Fast and effective feature-preserving mesh denoising. IEEE Transactions on Visualisation and Computer Graphics 13, 925–938.] are closer to the original data and to the ground truth. Changes to the data are smaller and less correlated to topographic features. Furthermore, the feature-preserving nature of the algorithm allows significant smoothing to be applied to flat areas of topography while limiting the alterations made in mountainous regions, with clear benefits for geomorphometric analysis in areas of mixed topography. The results of denoising on the derived flow accumulation and slope maps, particularly when compared to the results of mean filtering, demonstrate the usefulness of the algorithm in fields such as hydrological modelling and landslide prediction.
ABSTRACT A numerically robust algorithm for computing ellipsoidal bounds on the state of a linear... more ABSTRACT A numerically robust algorithm for computing ellipsoidal bounds on the state of a linear, discrete-time dynamic system was proposed. The algorithm employed ellipsoidal outer approximation of the feasible set assuming instantaneous process and observation noise vectors and the initial state to be bounded by known ellipsoids. The time and observation updates produced, respectively, the vector sum and intersection of two ellipsoids. Cholesky decomposition was used in the propagation of the shape-defining matrix of the ellipsoid to keep it positive definite in the presence of roundoff errors. Besides, a subminimal-volume ellipsoid was selected from a family of ellipsoids as the observation-updated ellipsoid to circumvent the complex optimization affected by ill-conditioned matrix inverse. Monte Carlo simulations on a digital computer were performed to compare the performance of the proposed algorithm with that of the optimal algorithm. Simulation results show that the proposed algorithm not only matches the performance of the optimal algorithm closely in terms of ellipsoid volumes and mean-square errors, but also is less vulnerable to roundoff errors. The proposed algorithm also features the capability to be realized on a parallel computer.
The control problems of chaotic systems are investigated in the presence of parametric uncertaint... more The control problems of chaotic systems are investigated in the presence of parametric uncertainty and persistent external disturbances based on nonlinear control theory. By using a designed nonlinear compensator mechanism, the system deterministic nonlinearity, parametric uncertainty and disturbance effect can be compensated effectively. The renowned chaotic Lorenz system subjected to parametric variations and external disturbances is studied as an illustrative example. From the Lyapunov stability theory, sufficient conditions for choosing control parameters to guarantee chaos control are derived. Several experiments are carried out, including parameter change experiments, set-point change experiments and disturbance experiments. Simulation results indicate that the chaotic motion can be regulated not only to steady states but also to any desired periodic orbits with great immunity to parametric variations and external disturbances.
Rate calibration and six position calibration tests are discussed about a kind of micro inertial ... more Rate calibration and six position calibration tests are discussed about a kind of micro inertial measurement unit (MIMU). A simple mathematical model of micro gyroscope and accelerometer is designed, some model parameters such as bias, scale factor, cross-axis coupling factors etc are confirmed. The effect of the model compensation is checked by the real tests. The tests result shows that gyroscope drift error compensated is near 0.01o/s, the accelerometer error is below 10 -3 g, the precision of MIMU is highly improved after error compensation, and the mathematical model is simple and the speed of calculation is also high.
The basic idea of intelligent transport systems(ITS) is introduced in this paper. GPS/INU/DM inte... more The basic idea of intelligent transport systems(ITS) is introduced in this paper. GPS/INU/DM integrated navigation location technology and its application in ITS are described. In addition, several technical measures to increase integrated navigation location precision and reliability are presented. This technology combines satellite navigation, inertial navigation with information technologies, and has all direction, 24 hours standby and non shadowed characteristics. The ‘automation’ of transportation management and the ‘intelligence’ of vehicular driving will be realized through using of integrated navigation location technology. Integrated navigation location technology has better practicing value and widely prospect.
ABSTRACT Noise in topographic data obscures features and increases error in geomorphic products c... more ABSTRACT Noise in topographic data obscures features and increases error in geomorphic products calculated from DEMs. DEMs produced by radar remote sensing, such as SRTM, are frequently used for geomorphological studies, they often contain speckle noise which may significantly lower the quality of geomorphometric analyses. We introduce here an algorithm that denoises three-dimensional objects while preserving sharp features. It is free to download and simple to use. In this study the algorithm is applied to topographic data (synthetic landscapes, SRTM, TOPSAR) and the results are compared against using a mean filter, using LiDAR data as ground truth for the natural datasets. The level of denoising is controlled by two parameters: the threshold (T) that controls the sharpness of the features to be preserved, and the number of iterations (n) that controls how much the data are changed. The optimum settings depend on the nature of the topography and of the noise to be removed, but are typically in the range T = 0.87–0.99 and n = 1–10. If the threshold is too high, noise is preserved. A lower threshold setting is used where noise is spatially uncorrelated (e.g. TOPSAR), whereas in some other datasets (e.g. SRTM), where filtering of the data during processing has introduced spatial correlation to the noise, higher thresholds can be used. Compared to those filtered to an equivalent level with a mean filter, data smoothed by the denoising algorithm of Sun et al. [Sun, X., Rosin, P.L., Martin, R.R., Langbein, F.C., 2007. Fast and effective feature-preserving mesh denoising. IEEE Transactions on Visualisation and Computer Graphics 13, 925–938.] are closer to the original data and to the ground truth. Changes to the data are smaller and less correlated to topographic features. Furthermore, the feature-preserving nature of the algorithm allows significant smoothing to be applied to flat areas of topography while limiting the alterations made in mountainous regions, with clear benefits for geomorphometric analysis in areas of mixed topography. The results of denoising on the derived flow accumulation and slope maps, particularly when compared to the results of mean filtering, demonstrate the usefulness of the algorithm in fields such as hydrological modelling and landslide prediction.
ABSTRACT A numerically robust algorithm for computing ellipsoidal bounds on the state of a linear... more ABSTRACT A numerically robust algorithm for computing ellipsoidal bounds on the state of a linear, discrete-time dynamic system was proposed. The algorithm employed ellipsoidal outer approximation of the feasible set assuming instantaneous process and observation noise vectors and the initial state to be bounded by known ellipsoids. The time and observation updates produced, respectively, the vector sum and intersection of two ellipsoids. Cholesky decomposition was used in the propagation of the shape-defining matrix of the ellipsoid to keep it positive definite in the presence of roundoff errors. Besides, a subminimal-volume ellipsoid was selected from a family of ellipsoids as the observation-updated ellipsoid to circumvent the complex optimization affected by ill-conditioned matrix inverse. Monte Carlo simulations on a digital computer were performed to compare the performance of the proposed algorithm with that of the optimal algorithm. Simulation results show that the proposed algorithm not only matches the performance of the optimal algorithm closely in terms of ellipsoid volumes and mean-square errors, but also is less vulnerable to roundoff errors. The proposed algorithm also features the capability to be realized on a parallel computer.
The control problems of chaotic systems are investigated in the presence of parametric uncertaint... more The control problems of chaotic systems are investigated in the presence of parametric uncertainty and persistent external disturbances based on nonlinear control theory. By using a designed nonlinear compensator mechanism, the system deterministic nonlinearity, parametric uncertainty and disturbance effect can be compensated effectively. The renowned chaotic Lorenz system subjected to parametric variations and external disturbances is studied as an illustrative example. From the Lyapunov stability theory, sufficient conditions for choosing control parameters to guarantee chaos control are derived. Several experiments are carried out, including parameter change experiments, set-point change experiments and disturbance experiments. Simulation results indicate that the chaotic motion can be regulated not only to steady states but also to any desired periodic orbits with great immunity to parametric variations and external disturbances.
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