[Show abstract][Hide abstract] ABSTRACT: Automatic vehicle extraction from an airborne laser scanning (ALS) point cloud is very useful for many applications, such as digital elevation model generation and 3D building reconstruction. In this article, an object-based point cloud analysis (OBPCA) method is proposed for vehicle extraction from an ALS point cloud. First, a segmentation-based progressive TIN (triangular irregular network) densification is employed to detect the ground points, and the potential vehicle points are detected based on the normalized heights of the non-ground points. Second, 3D connected component analysis is performed to group the potential vehicle points into segments. At last, vehicle segments are detected based on three features, including area, rectangularity and elongatedness. Experiments suggest that the proposed method is capable of achieving higher accuracy than the exiting mean-shift-based method for vehicle extraction from an ALS point cloud. Moreover, the larger the point density is, the higher the achieved accuracy is.
[Show abstract][Hide abstract] ABSTRACT: In this paper, study of a novel flexible robotic-fin actuated by Shape Memory Alloy (SMA) is presented. The developed robotic fin is capable of implementing various 3-Dimensional (3D) motions, which plays an important role in robot propulsion and maneuverability. Firstly, the morphological and mechanics parameters of a real pectoral fin from a carp are investigated. Secondly, a detailed design of the flexible pectoral fin driven by SMA is presented according to the previous morphological and mechanics analyses. Thirdly, a simplified theoretical model on the SMA fin plate is derived. The thermodynamics of the SMA plate and the relationship between curvature and phase transformation are analyzed. Finally, several simulations and model experiments are conducted according to the previous analyses. The results of the experiments are useful for the control of the robotic fin. The experimental results reveal that the SMA actuated fin ray has a good actuating performance.
Journal of Bionic Engineering 06/2012; 9(2):156–165. · 1.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this article, an unsupervised clustering approach, known as the kernel fuzzy C-means (KFCM), which is based on Cloude's decomposition, is used for polarimetric synthetic aperture radar (POLSAR) image classification. The KFCM algorithm is an improved version of the fuzzy C-means (FCM) algorithm. It replaces the original Euclidean distance measure by the kernel-induced distance. The original sample space, coherency matrix T, is mapped to a higher-dimensional feature space so as to simplify the complex POLSAR data by using the Gaussian kernel function. The method has three main steps: first, the eight initial centres are obtained by averaging the coherency matrix within each partition according to the classical H/α plane so as to preserve the polarimetric property reasonably well; second, the related parameters of the KFCM algorithm are iteratively refined and third, the membership matrix is defuzzified by using the maximum membership decision rule. The distance measure used in the algorithm is derived from the complex Wishart distribution of the pixel data presented in the coherence data. The KFCM method not only takes advantage of the polarimetric scattering properties but also utilises the kernel method to cluster the nonlinear structure data with noise. The feasibility of this approach was tested by using two JPL/AIRSAR polarimetric SAR images. The experimental results showed that the KFCM clustering algorithm was better than the FCM clustering algorithm at classifying the POLSAR images.
International Journal of Image and Data Fusion. 01/2012;
[Show abstract][Hide abstract] ABSTRACT: Due to steep terrain relief and complex geomorphic types in Hengduan Mountain area, COSMO tandem with short temporal separation and the interferometric baseline revealed high potential for large area topographic mapping. Topography is mostly serious with steep slopes and covered by permanent snow. Furthermore, the quality of the InSAR DEM may vary significantly depending on the local topography. Interferometric processing consisted of coregistration of COSMO image pairs, multi-looking, range and azimuth direction filtering, interferogram generation and coherence map calculation, phase unwrapping; in areas of low coherence larger windows were used to reduce the uncertainty and bias of the estimation. For the geocoding of the COSMO DEM, Range-Doppler model based on few control points was used to build the relationship between ground point geodetic coordinates and image coordinates. Maps have been produced for a 15 000km 2 large area in China in western mapping project. At present, the proposed method, technical flow and software module has been widely used in the 1:50000 Scale Topographic Mapping Project in Western China. The experiment result proves that it is effective and practical.
[Show abstract][Hide abstract] ABSTRACT: A high precise tree height retrieval method is presented in this paper. The accuracy of ground and canopy phases in vegetation area extracted by different algorithms are firstly estimated using PolInSAR(Polarmetric SAR Interferometry) images simulated by PolSARProSim software, and then the effect of ground moisture and roughness on phases extraction are also analyzed. The research shows that the relatively "pure" phase of ground and canopy can be extracted by PD(Phase Diversity) algorithm, which can be used to build more precise tree height model. Ground moisture has little effect on phases while ground phases depend on ground roughness, which almost has no effect on canopy phases.
[Show abstract][Hide abstract] ABSTRACT: The airborne X-band Interferometric SAR (InSAR) image has more detailed spatial information compared with P-band full Polarimetric SAR (PolSAR) image, conversely, P-band full PolSAR images have more abundant polarization and color information. The fusion of these two bands of SAR images may enhance information and improve interpretation capabilities. Nonsubsampled Contourlet Transform (NSCT) can represent images more effectively because of its flexible multi-scale, multi-direction and shift invariance. IHS fusion algorithm has the advantage of good performance in maintaining color information and details of images. Combining the full advantages of these two techniques, a novel IHS-NSCT based image fusion method of X-band InSAR and P-band full PolSAR images was proposed in this paper. Experiments show that the proposed method can perform better than some other methods, in terms of the visual quality, noise reduce and the improved spatial information.
[Show abstract][Hide abstract] ABSTRACT: Many researchers have developed some soft robots which mimic the mollusks movements having power ability to interact with their environments, but these soft robots usually have only one locomotion mode, which cannot effectively take into account the movement efficiency and the environment adaptability simultaneously. This paper presents the design of a novel soft robot which has three locomotion modes; namely, rolling, Omega crawling and vermiculation. It can effectively give consideration to the high efficiency for the rolling, the strong obstacle climbing capability for the Omega crawling and the capacity passing through a narrow space for the vermiculation. By controlling the body deformation and the connection mechanism of the head and the tail separation, we can realize the three locomotion modes and their switching. Firstly, we present the principle of three locomotion modes and how to switch them, and then the detailed structure design of the soft robot is delivered. Secondly, the initial simulation and experiment for the rolling locomotion are fulfilled to verify the feasibility of the soft robot, as the rolling locomotion is most difficult to realize in three locomotion modes.
[Show abstract][Hide abstract] ABSTRACT: Fish are capable of remarkable locomotor performance through the complex 3D motions and the cooperation of different fins. Specially, pectoral fins play an important role to provide thrust, maneuverability and balance ability. In this paper, a novel design of a flexible pectoral fin capable of 3D motions actuated by Shape Memory Alloy (SMA) is proposed. The flexible pectoral fin can perform five basic gestures of real pectoral fins: Relaxed, Expansion, Bending, Cupping and Undulation. First, we present the mechanical design of the flexible pectoral fin, and then put forward two effective designs (Plate Mode and Wire Embedded Mode) of fin ray, the basic actuated unit of the pectoral fin, capable of bending in two mutually orthogonal directions. Second, we conduct theoretical analysis of the SMA fin ray respectively based on the two designs. Finally, a series of experiments are conducted to investigate the performance of the two designs, meanwhile, the comparison between the two is given out.
Mechatronics and Automation (ICMA), 2010 International Conference on; 09/2010
[Show abstract][Hide abstract] ABSTRACT: Fish are noted for their excellent performances to cruise efficiently, to maneuver and to position themselves accurately. These performances are the result of complex 3D motion and the cooperation of different fins of fish. In this paper, we focus on the research of the pectoral fin, and present a novel mechanical design of flexible pectoral fin capable of 3D undulation, actuated by shape memory alloy (SMA). First, we implement a detailed design of flexible pectoral fin which is composed of a series of SMA fin rays. Each fin ray consists of two serial installed SMA plate couples and is capable of bending in two mutually orthogonal directions. Second, we analyze the energy distribution of the response process of the SMA plate couple from the aspect of thermodynamics, meanwhile, we conduct a thermodynamics simulation to research the response process. Third, the control system is designed to obtain the accurate control of the locomotion of the fin ray. Finally, we conduct experiments to investigate the performance of the SMA fin ray and attain the following results: (a) relationship between temperature and actuation time; (b) relationship between angular displacement and time; (c) relationship between torque and current. The experimental results show that SMA driven fin ray has a good performance and that the SMA driven flexible pectoral fin can be well achieved.
Robotics and Biomimetics (ROBIO), 2009 IEEE International Conference on; 01/2010
[Show abstract][Hide abstract] ABSTRACT: We present experimental velocity, propulsion force and power measurements finding out that the significance level of shape and kinematics parameters of robotic fin to its propulsion performance. The data have been obtained through synchronous velocity, propulsive force and the power measurements on an undulatory robotic fin mechanism, at the Reynolds numbers 10<sup>6</sup>. The lateral motion of the robotic fin is in the form of a travelling wave, the kinematics parameters we investigated are frequency, amplitude, wavelength and envelope line. According to the data of velocity, propulsive force and the power measurements, the propulsion efficiency can be conducted. The experimental result indicates that the velocity, propulsive force and propulsion efficiency is optimum with the fin shape is isosceles trapezoid, the frequency and amplitude of fluctuation is 1.67Hz and 100 mm respectively. The optimization result is meaningful for the mechanical design of undulatory fin propulsion.
Robotics and Biomimetics (ROBIO), 2009 IEEE International Conference on; 01/2010
[Show abstract][Hide abstract] ABSTRACT: At present, object-extraction is one of the key problems of the data-procession to the aerial LIDAR dataset. The aim of this paper is to research the methods to classify and extract the object-points from the cloud points obtained by the aerial LIDAR system. In this paper, based on the different feature of elevation and intensity of different objects, the laser-points of buildings, vegetation and water are individually extracted. Then, several experiments are given to validate the effectivity of the object-extraction methods.
Computer Modeling and Simulation, International Conference on. 01/2010; 4:299-302.
[Show abstract][Hide abstract] ABSTRACT: We present experimental velocity, propulsion force and power measurements finding out that the significance level of shape and kinematics parameters of robotic fin to its propulsion performance. The data have been obtained through synchronous velocity, propulsive force and the power measurements on an undulatory robotic fin mechanism, at the Reynolds numbers 106. The lateral motion of the robotic fin is in the form of a travelling wave, the kinematics parameters we investigated are frequency, amplitude, wavelength and envelope line. According to the data of velocity, propulsive force and the power measurements, the propulsion efficiency can be conducted. The experimental result indicates that the velocity, propulsive force and propulsion efficiency is optimum with the fin shape is isosceles trapezoid, the frequency and amplitude of fluctuation is 1.67Hz and 100mm respectively. The optimization result is meaningful for the mechanical design of undulatory fin propulsion.
Proceedings of the 2009 international conference on Robotics and biomimetics; 12/2009
[Show abstract][Hide abstract] ABSTRACT: Powerline vegetation management has been a labor intensive and costly practice for energy companies. This situation may be improved with use of new positioning and remote sensing technologies. This paper provides reviews and comparisons for a number of state-of-art powerline extraction and modeling methods using the aerial, radar and laserscaning images. The prospect and feasibility of powerline surveillance using remote sensing technology are also presented.
[Show abstract][Hide abstract] ABSTRACT: During the mapping task using high-resolution airborne SAR images, the effective using of DGPS data has important influence on the final accuracy and efficiency of surveying and mapping. This paper analyzed the imaging geometric characteristics of airborne SAR system, and, under the condition of space-constant PRF imaging technique, it put forward to a kind of flight track processing method for radar sensor position correction using iteration computation supported by DGPS data. And further, it discussed the data processing flow for direct geo-location application from airborne SAR images, and utilized the test dataset in Sichan area in China to testify the relative methods. The test results showed that the methods are reliable and effective, and it can improve the research on direct geo-location from airborne SAR images as a reference method.
Education Technology and Training & Geoscience and Remote Sensing. 12/2008; 2:456-459.
[Show abstract][Hide abstract] ABSTRACT: In this paper, a carangiform robotic fish with 4-DoF (degree of freedom) tail has been developed. The robotic fish has capability of swimming under two modes that are radio control and autonomous swimming. Experiments were conducted to investigate the influences of characteristic parameters including the frequency, the amplitude, the wave length, the phase difference and the coefficient on forward velocity. The experimental results shown that the swimming performance of the robotic fish is affected mostly by the characteristic parameters observed.
[Show abstract][Hide abstract] ABSTRACT: In this paper, an automated road extraction from high-resolution remote sensing images method based on road synthetical characteristics is presented. First, spectral property, geometric property and textural property of road class have been considered and a road clustering model has been established. Second, mathematical morphology has been applied to extract road centerlines. Experiments prove that the model of this paper could describe the features of road well and accurately identify the road class from high-resolution remote sensing images.
[Show abstract][Hide abstract] ABSTRACT: SPOT 5 satellite was launched on May, 4th, 2002. It has some new distinguished characteristics, for example that its ephemeris and attitudes on orbit can be accurately measured, recorded and distributed within DIMAP format which is a newly designed format for SPOT 5 imagery. DIMAP’s metadata, usually named Metadata.dim, contains plenty of detailed information of imagery acquisition, satellite ephemeris and attitudes, view directions of each CCD and line sample intervals, etc. All of those data make it reach reality to perform image positioning with few GCPs and rigorous satellite physical model. Based on the built rigorous satellite physical model by authors, they carried out image positioning experiments and accuracy assessment with one scene of SPOT HRG image and two scenes of SPOT HRS image, in order to determine the suitability of the built model to few GCPs and the accuracy that SPOT 5 image positioning can achieves. The content in the paper includes two experiments, one is SPOT 5 image positioning accuracy assessment, whose aim is to test SPOT 5image positioning accuracy basing on the built model, another one is model suitability test whose aim is to test the ability of the model under diverse GCPs and differentcoordinate systems. Finally someimportant,conclusions are drawn. 1.,INTRODUCTION Image rectification with few GCPs(Ground Control Points) has
[Show abstract][Hide abstract] ABSTRACT: For the high-resolution airborne synthetic aperture radar (SAR) stereo geolocation application, the final geolocation accuracy
is influenced by various error parameter sources. In this paper, an airborne SAR stereo geolocation parameter error model,
involving the parameter errors derived from the navigation system on the flight platform, has been put forward. Moreover,
a kind of near-direct method for modeling and sensitivity analysis of navigation parameter errors is also given. This method
directly uses the ground reference to calculate the covariance matrix relationship between the parameter errors and the eventual
geolocation errors for ground target points. In addition, utilizing true flight track parameters’ errors, this paper gave
a verification of the method and a corresponding sensitivity analysis for airborne SAR stereo geolocation model and proved
Keywordsairborne SAR-stereo-sensitivity analysis-parameter error-geolocation