A Maneuver Detection Method using Multiple Doppler Radars

The receiver of a global navigation satellite system (GNSS) is likely to lose tracking for a GNSS signal in some degraded environments. To solve this problem, this paper designs a new adaptive tracking algorithm for GNSS signals. First, we design an error extraction module to extract phase errors so that a CTL can estimate phase errors without using a loop discriminator, which can reduce the requirements of the carrier-to-noise ratio (CNR) of GNSS signals. Second, we design a motion detection module to detect the real-time movement status of GNSS receivers. Then, using its detecting results as inputs, we design an algorithm to automatically make the CTL switch between a second-order loop and a third-order loop. Third, we design a bandwidth-adjusting module to adjust the bandwidth of CTL, according to the CNR and the movement status of a GNSS receiver. Finally, a simulation is performed to verify that our adaptive carrier tracking algorithm can effectively improve the precision of CTL, as well as enhance its dynamic range.

Visual tracking has been widely used in robot systems, and numerous approaches for visual tracking have been proposed. However, developing a robust and real-time visual tracking algorithm which can adaptively track the varying appearance of target under challenging conditions for mobile robot is still an open problem. This paper presents an adaptive probabilistic tracking algorithm with multiple cues integration. An effective evaluation function is proposed to evaluate each cue used for tracking based on their discriminating abilities between foreground and background. Then the likelihood functions of the cues are integrated in particle filter framework with different weights determined based on the evaluation scores. A novel target model updating strategy is proposed to adapt to the varying appearance of target resisting gradual drift which is still an unsolved problem in many adaptive tracking algorithms. Experimental results on a mobile robot demonstrate the robust performance of the proposed algorithm under challenging conditions.

In the context of space situational awareness, orbit determination and maneuver detection pose considerable challenges given the ever increasing number of noncooperative satellites that perform unspecified maneuvers at unknown epochs. A new metric is proposed for maneuver detection here, based on measurements from a single surveillance radar. Data from the radar track are leveraged to derive this metric; it can flag the occurrence of a maneuver since the last time a satellite was observed. In the scenarios considered in this work, the main challenge is having just a few available observations in between long propagations. Thus, a realistic quantification of uncertainty becomes crucial; Gaussian mixtures are chosen for this work. The propagated state is compared against the radar track data to compute a well-known cost metric, the evidence in Bayes’s update, similar to the Mahalanobis distance (MD). The contribution of this work lies in using the variation of the cost metric across track points to define a new maneuver detection metric. The focus is on testing this new metric in diverse and realistic scenarios to gain practical intuition about its performance and limitations. The preliminary results are promising, simultaneously improving upon the classical MD at maneuver detection and reducing false positives.

The development of several large thunderstorms that occurred on June 22, 1982 within the Joint Airport Weather Studies (JAWS) network near Denver, Colorado is examined together with that of six microbursts and one microburst line produced by the storms. From the analysis of single and multiple Doppler radar and surface network data, it is concluded that the microbursts on June 22 were predominantly driven by microphysical and related thermodynamic effects due to precipitation loading and water-phase change; dynamic effects did not appear to be of primary importance. Surface network observations permitted identification of some of the microbursts, but early detection was not possible.

This study develops an extension of a variational-based multiple-Doppler radar synthesis method to construct the three-dimensional wind field over complex topography. The immersed boundary method (IBM) is implemented to take into account the influence imposed by a nonflat surface. The IBM has the merit of providing realistic topographic forcing without the need to change the Cartesian grid configuration into a terrain-following coordinate system. Both Dirichlet and Neumann boundary conditions for the wind fields can be incorporated. The wind fields above the terrain are obtained by variationally adjusting the solutions to satisfy a series of weak constraints, which include the multiple-radar radial velocity observations, anelastic continuity equation, vertical vorticity equation, background wind, and spatial smoothness terms. Experiments using model-simulated data reveal that the flow structures over complex orography can be successfully retrieved using radial velocity measurements from multiple Doppler radars. The primary advantages of the original synthesis method are still maintained, that is, the winds along and near the radar baseline are well retrieved, and the resulting three-dimensional flow fields can be used directly for vorticity budget diagnosis. If compared with the traditional wind synthesis algorithm, this method is able to merge data from different sources, and utilize data from any number of radars. This provides more flexibility in designing various scanning strategies, so that the atmosphere may be probed more efficiently using a multiple-radar network. This method is also tested using the radar data collected during the Southwest Monsoon Experiment (SoWMEX), which was conducted in Taiwan from May to June 2008 with reasonable results being obtained.

NURBS interpolation is highly requested in CNC systems because it allows high speed and high accuracy machining. In this work, an algorithm for NURBS interpolation capable of limiting chord error, centripetal acceleration and tangential acceleration is proposed. The algorithm is composed of two stages that may be executed simultaneously. In the first stage, the algorithm breaks down the curve into segments and, for each segment, calculates the feedrate limit that allows to respect both chord error tolerance and maximum centripetal acceleration limit. The second stage is a speed-controlled interpolator with a tangential acceleration limited feedrate profile generated using information provided by first stage. Software simulations are performed to verify the fulfillment of constraints and performance is compared to those of speed-controlled interpolator and variable feedrate interpolator.

To investigate the problem of improving tracking performance in wide monitoring area for netted multi-sensor system, an adaptive tracking algorithm with variable observation (ATVO) based on the scheme of monitoring area segmentation is derived. During the computational process of target tracking, the sub monitoring field of the target is calculated by its position estimation and observation distribution matrix (ODM) is introduced to adaptively adjust measurement system of equations. Observing equations with low accuracy are eliminated and observing equations with high accuracy are reserved. Simulation results show that ATVO not only ensures the precision of state estimation but also reduces the dimension number of observation equations. The accuracy and real-time capability of tracking moving target are improved.

An adaptive template matching-based single object tracking algorithm with parallel acceleration

Continuous-wave (CW) Doppler radar with a quadrature direct-conversion receiver (DCR) has critical issues about Direct-current (DC) offset to manage and measure it when remotely monitoring vital signs which are closely resemble DC values. The characterization process using Radio frequency (RF) single tone has been carried out to measure DC offset, but there is no known method for supporting multiple CW. This paper categorizes DC offset as one of a system DC offset and an environment DC offset, and proposes 1 to 5 experiments of a DC offset characterization process supporting multiple CW. The result experimentally shows that DC offsets have the tendency to follow experiment 4 of characterization when the RF-to-local oscillator (LO) isolation is achieved by using the absorber in front of the antenna.

—The hypothesis of a natural sophisticated RADAR tracking system affecting hornets flight was described, analyzed and developed in previous papers [1, 2] considering their (cuticle) skin complex spike elements arrays shown by electronic microscope pictures. The existence of different spike length arrays and their disposition lead, by analogy with antenna, and radio theory and practice, to the hypothesis of transmitting and receiving phased arrays antennae operating at three different wavelengths in the sub-millimetric bands. The natural photo-and piezo electric generation of energy in the hornets reported previously explain how is generated the Radio Frequency (RF) energy required for the operation of the sub-millimeter wavelength natural RADAR system. However, similar to bats, new computation results show that the operation range of hornets RADAR system is limited to less than 100 m. Recently, investigations have shown that also in the hornet two antennae are located hundreds of spikes which may radiate and detect significant radio energy from their internal photo electric sources and piezoelectric effect. Thus, the existence of three separate sources of radiation and detection enable the application of Direction Finding (DF) communication additional hypothesis. The DF concept can contribute

The SOPLAT (Single Observer Location And Tracking) technique has been used in bistatic systems, in which the transmitter only emits radar signal, and there is no need for synchronization between the transmitter and receiver. Under conditions of knowing PRF of radar signals emitted by the transmitter and the position of the transmitter, an algorithm, WMEKF (Weighted Modified Extended Kalman Filter) can be used to locate and track targets moving with constant speed by means of DOA and TOA measurement series. But for maneuvering targets, WMEKF algorithm is easily diverging, so it is not applicable. A new method for tracking maneuvering targets in bistatic systems with an independent receiver is described. Based on WMEKF algorithm, this paper introduces an adaptive tracking algorithm AWMEKF with a maneuvering detector for tracking maneuvering targets. Its performance for typical maneuvering target paths is evaluated by means of computer simulation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Uniform circular motion is one of the key mechanics topics in Physics that students fail to comprehend and master. In South Africa, uniform circular motion is currently not taught to Physical Sciences Matriculate learners and thus students are only introduced to it at university level. It is appreciated that poor comprehension of fundamental concepts and tenets of uniform circular motion leads to difficulties in understanding related topics such as Rotational Kinematics and Rotational Dynamics. This study investigated student teachers’ misconceptions about uniform circular motion and its pertinent underlying concepts such as tangential acceleration and centripetal acceleration. The study also attempted to figure out the source(s) of the ensuing misconceptions. The sample of the study consisted of 41 second-year Physical Sciences student teachers at a South African university. A multiple-choice test consisting of 20 questions on uniform circular motion was administered. Simple and explanatory statistical techniques were employed to analyse the data and appropriate intervention methods were proposed to curtail the identified misconceptions. The study revealed that factual misconceptions and conceptual misunderstandings were prevalent amongst the student teachers who took part in the research exercise.

To solve the problem of super-speed maneuvering target tracking in the 3D space. An adaptive algorithm for the super-speed tracking using the radial velocity was presented for radar awareness system, which can detect target radial velocity and target angular velocity. Compared with the traditional algorithm for variable structure multiple models (VSMM) in the track of target maneuvering by the simulation analysis. The simulation result shows that this algorithm has more simple structure, higher positioning accuracy and better maneuver detection. The new tracking algorithm has some value for project practice.

Forty years of cross-disciplinary academic and industrial research & development work on radar tracking systems is surveyed, starting from the former implementations based on the α - β, the Kalman filter up to the modern implementations based on random set filters.

For the tracking problem of moving target with scale changes, an adaptive bandwidth tracking algorithm based on principal component variation detection of histogram is proposed. Considering feature characteristics of target and background, such as conspicuousness and similarity, discrimination is estimated to select the feature which can differentiate the target and its background to its extent. The number of feature bins is determined by the discrimination. Target scale variation is analyzed by the number of pixels of principal component in histogram. A novel bandwidth criterion is defined to adjust the tracking window adaptively. Simulation shows that the algorithm can detect the scale change of the target and track the target more accurately.