Pedestrian detection is an indispensable technology for designing autonomous driving systems. This paper proposes a cascaded sliding window based real-time approach to generate 3D pedestrian proposals on point clouds ...
Pedestrian detection is an indispensable technology for designing autonomous driving systems. This paper proposes a cascaded sliding window based real-time approach to generate 3D pedestrian proposals on point clouds only. After rasterizing the raw point cloud, a 3D sliding window is adopted to extract pedestrian candidates. Two features are proposed to improve the proposal performance. One is the central points density feature, which acts as a filter to speed up the process and reduce false alarms. The other is the location feature, including the density distribution and height difference distribution of the point cloud, which describes the profile and location of an object in a sliding window. The scores generated by this feature are then applied to non-maximum suppression (NMS) to remove sub-optimal boxes. Experiments on the KITTI 3D object detection benchmark show that our approach achieves state-of-the-art results among comparable methods, while maintaining the speed and accuracy trade-off.
With the advantages of strong anti-interference ability and high spatial resolution, electromagnetic induction (EMI) has proven to be successful in unexploded ordnance (UXO detection. Portable transient electromagneti...
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With the advantages of strong anti-interference ability and high spatial resolution, electromagnetic induction (EMI) has proven to be successful in unexploded ordnance (UXO detection. Portable transient electromagnetic system can work in a variety of complex conditions where the large and heavy vehicular systems cannot be readily used. The detection of UXO-like targets with portable transient electromagnetic (TEM) system is discussed detailed in this paper. Firstly, with description of the single dipole model for UXO response approximation, the location and characteristic response extraction for UXO-like targets is talked with the DE algorithm. Then, the improved sensor of the portable TEM system with a single-layered transmitting coil and five 3-component receiving coils is introduced. The transmitting coil is constructed with a diameter, number of turns, and transmitting current of 0.5 m, 30, and 5 A, respectively. The receiving coil is constructed with a length, number of turns, and resonant frequency of 6 cm, 600, and 180 kHz, respectively. Finally, 12 UXOs and 6 harmless targets buried in the area of 10 m × 6 m at different depths in different orientations have been detected with the improved portable TEM system. Target location and characteristic response have been estimated by DE algorithm with the measured response. The experimental results show that the high-quality data provided by the improved portable TEM system combined with the DE algorithm based on the dipole model can locate and characterize the separated targets accurately. Most of the position errors are within 10cm in x position and 5cm in depths for separated buried targets. For the multiple-targets buried together, the system can still locate and characterize the targets even if the response of two targets overlaps.
Off-time response is usually measured by transient electromagnetic (TEM) system to detect subsurface targets. Compared with off-time response, on-time response of TEM system is more sensitive to high-conductivity targ...
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Off-time response is usually measured by transient electromagnetic (TEM) system to detect subsurface targets. Compared with off-time response, on-time response of TEM system is more sensitive to high-conductivity targets, such as UXOs. However, it is difficult to obtain on-time response directly due to the strong primary field response. The key problem for on-time measurement is to eliminate the primary field response. Bucking coil is adopted here to compensation the primary field of transmitter coil at receiving coil for on-time response measuring. Firstly, the structure of the sensor with transmitting coil, bucking coil, and receiving coil is presented. Then, the primary field of transmitting coil and bucking coil at the position of receiving coil is calculated theoretically. With the side length of transmitting coil, bucking coil and the receiving coil fixed, the number of turns for transmitting coil and bucking coil are optimized for the best compensation. Calculated results show that the best compensation effect can reach 0.53%. Finally, the sensor with a transmitting coil (constructed with a side length and number of turns of 96 cm and 30, respectively), a bucking coil (constructed with a side length and number of turns of 26 cm and 8, respectively), and a receiving coil (constructed with a side length of 6 cm) was built. Measured results show that the primary field response after compensation is no more than 1% of the original response, and the maximum amplitude is only 0.4V. The on-time response of targets can be accurately recorded.
It is a key problem to locate a buried target in UXO detection. The inversion algorithm based on the principle of least squares requires a large number of forward calculations to estimate the position of a target. The...
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It is a key problem to locate a buried target in UXO detection. The inversion algorithm based on the principle of least squares requires a large number of forward calculations to estimate the position of a target. The method of auxiliary sources (MAS) which can directly locate a UXO-like target is presented here without forward calculation. With a brief description of single dipole model for a UXO-like target, the basis of target location with magnetic field and scalar magnetic potential is deduced theoretically. Auxiliary sources made of elementary magnetic dipoles on a plane are applied to estimate the equivalent scalar magnetic potential from the measured magnetic field. Firstly, the moment of elementary magnetic dipoles is estimated by matching the measured magnetic field with the auxiliary sources modeled field. Then, the equivalent scalar magnetic potential is calculated with these elementary magnetic dipoles without a priori knowledge of the target's location. Finally, the position is calculated directly with the measured magnetic field and the equivalent scalar magnetic potential. The responses of four UXOs excited by a z-component square transmitting coil are recorded by a 9×9 3-component receiving coil array. With the auxiliary sources on a plane under the measurement grid, the equivalent scalar magnetic potential is calculated precisely. Experimental results show that the measured magnetic field matches well with the auxiliary sources modeled field, and the estimated positions of all targets are highly consistent with the measured ones. The horizontal error is within 2 cm, and the depth error is within 6 cm.
Aiming at the problem of eliminating the influence of channel interference on the detection results in the process of using sonar to detect very shallow water targets, a sonar image reconstruction method based on adap...
Aiming at the problem of eliminating the influence of channel interference on the detection results in the process of using sonar to detect very shallow water targets, a sonar image reconstruction method based on adaptive compensation of very shallow water acoustic channel features is proposed. Standard acoustic source and remote server are used to complete the adaptive calibration process of channel characteristic parameters before detection. The calibrated channel characteristic parameters are used in the subsequent beamforming algorithm to compensate the channel interference. The time-of-flight parameters calculated by the compensation algorithm are used in the subsequent point cloud generation and image reconstruction. Simulation and field test show that the proposed compensation method can improve sonar target detection ability by 25% in very shallow water and complex acoustic channel environment, and the quality of sonar image reconstruction is significantly improved.
The motion state of the ocean surface is changeable and has special irregularity. It is impossible to describe these characteristics in detail, which leads to the low accuracy of simulation for the sea surface. A simu...
The motion state of the ocean surface is changeable and has special irregularity. It is impossible to describe these characteristics in detail, which leads to the low accuracy of simulation for the sea surface. A simulation method of realistic dynamic ocean surface based on 3D sonar image algorithm is proposed. The number of adjacent points iteration of two adjacent images is calculated, and all the dynamic shallow surface sonar images are matched and combined. According to the edge coordinate information between the nearest adjacent images, the overlapping part between the two sonar image frames is analyzed. The two frames of sonar images beyond the threshold range of overlap are registered by ICP algorithm, The simulation of the dynamic ocean surface with the statistical model and FFT based wave generation method is carried out. The simulation results show that the research method of 3D sonar image algorithm is more accurate and can achieve more real simulation results.
Localization of unexploded ordnance (UXO) with transient electromagnetic (TEM) system is a principle and necessary problem in detection procedures, especially beset by low data diversity and high positioning uncertain...
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Localization of unexploded ordnance (UXO) with transient electromagnetic (TEM) system is a principle and necessary problem in detection procedures, especially beset by low data diversity and high positioning uncertainty. In this paper, procedures for targets location are presented in detail with cued data collected by potable TEM sensor JPMD, which is designed to provide diverse time-domain data of high quality with one transmitter coil and five 3-component receiving coils. Based on the single dipole model, the target is located with the data collected at a single spatial point by the differential evolution (DE) optimization algorithm which can be subdivided into three steps. With the structure and parameters of JPMD sensors and data inversion process described briefly, a field test site of 5 m × 5 m measurement grid was conducted to present the specific UXO localization procedures at Jilin University. Results indicate that all the UXO-like targets can be detected distinctly with JPMD. The location of single object can be inversed rapid in tolerable error at one single point. For two objects with overlapping signals as one, the inverted horizontal position is basically in the middle of them and depth is a bit smaller than theory.
Today's science and technology develop rapidly with the passage of time. In the highly competitive environment, everyone's time is twenty-four hours a day. No one can have more than one minute. Or less have a ...
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ISBN:
(数字)9781728166520
ISBN:
(纸本)9781728166537
Today's science and technology develop rapidly with the passage of time. In the highly competitive environment, everyone's time is twenty-four hours a day. No one can have more than one minute. Or less have a minute to go, so if you want to improve your competitiveness, efficient scheduling time is very important, people's daily needs for efficiency are also growing. In the process of moving these vehicles, how to move the same distance with others in less time, this demand and efficiency can also be seen from the tools we now use to produce vehicles (such as tricycles).In the high-precision control system design of the self-balancing vehicle of the tricycle vehicle, in addition to the high-precision inclination sensor to measure the dynamic inclination angle, the steering control has an absolute value encoder to learn the angle of the steering of the tricycle body. More importantly, in addition to the rear axle drive system on the wheel of the tricycle body itself, we also installed a stepper motor to control the balance of the tricycle body, so that the tricycle body can be at a higher speed. Under the steady steering, the tricycle body will not roll *** attitude measurement is a very important aspect in the design of high-precision control systems for self-balancing vehicles of tricycle vehicles. Because the motor is an open-loop system, we need to use the tilt sensor for attitude measurement to obtain high-precision angle values, and the obtained angle value and the motor form a closed-loop control system to achieve more precise motor control to control the tricycle body. balance. So we need to measure the angle change very accurately, because a single axial attitude tilt sensor can't meet our requirements, and because there are too many shortcomings, we can't get more accurate values in a dynamic environment, so we use A six-axis sensor that helps us get better precision and precision. Finally, we use the VEKF-based algorithm to eliminate the numerical
In order to solve the practical operation training problem of an optical sighting telescope in certain weapon system, the application research of simulated target technology is carried out. According to the tactical a...
In order to solve the practical operation training problem of an optical sighting telescope in certain weapon system, the application research of simulated target technology is carried out. According to the tactical and technical characteristics of sight and battlefield target, based on the embedded simulation framework, a series of simulation target technologies, such as constructing the optical characteristic model of target, fitting the target trajectory, encapsulating the characteristic information of target in the typical scene, are used to explore the technical route of actual combat training relying on actual equipment and simulation target, and realize the training scene and its model. The application results show that the method is feasible.
The instrument detection methods of underwater part of beach obstacle mainly include multi-beam bathymetric system and three-dimensional panoramic imaging sonar system. SeaBat T50-P multi beam bathymetry and BV5000-13...
The instrument detection methods of underwater part of beach obstacle mainly include multi-beam bathymetric system and three-dimensional panoramic imaging sonar system. SeaBat T50-P multi beam bathymetry and BV5000-1350 sonar system are widely used in the area of underwater detection. The underwater part of beach obstacles is measured and analyzed, and the application scope of both equipment is discussed. The results show that the BV5000-1350 sonar system can be used to detect underwater incomplete obstacles with wider application scope, high accuracy, convenient installation of instruments, and no auxiliary equipment such as navigation, positioning and attitude sensor is needed; SeaBat T50-P multi-beam bathymetric system has high requirements for the structure of the measured object, moderate accuracy, and is more suitable for large-scale underwater obstacle survey.
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