A Track-Before-Detect Strategy Based on Sparse Data Processing for Air Surveillance Radar Applications

In this paper we consider the tracking problem of a moving target competing against noise and clutter in a surveillance radar scenario. For a single array-antenna multiple-target tracking system and according to the Track-Before-Detect paradigm, we present a novel approach based on a three-stage processing chain that involves the Sparse Learning via Iterative Minimization algorithm, the k-means clustering method and the ad hoc detector by exploiting the sparse nature of the operating scenario. Under the latter assumption, the detection strategy declares the presence of targets subsequently to the retrieval of their corresponding tracks performed by jointly processing the received echoes of multiple consecutive radar scans. Simulation results show that the proposed approach is able to provide good tracking and detection capabilities for different multiple target trajectories with low Signal-to-Interference-plus-Noise ratio and results in providing advantages when compared to a number of other reference Track-Before-Detect strategies based on sparse data processing techniques.

Position Control of a Solenoid Based Linearly Movable Armature System using Robust Control Technique

In this paper, a solenoid based linearly movable armature system is designed using robust control theory in order to improve the performance of the system. Reference track method is the best performance analysis for position control systems. Among the robust controllers, H infinity mixed-sensitivity and Mixed H 2 /H∞ with Regional Pole Placement Controllers are used to improve the performance of the system. Comparison of the proposed controllers for tracking a reference displacement signals (step and sine wave) and a promising simulation result have been obtained.

Assessment of the performance and effects of metro-induced ground-borne vibration for mitigation measures of resilient tracks

A methodology that judges the performance and estimates the effects of metro-induced ground-borne vibration is presented for the mitigation measures of resilient tracks. Two criteria are proposed for the purpose of judgment and estimation, respectively. One is the force ratio obtained by comparing the forces transmitted to the track bed of the resilient track with those of a reference track. As the force ratio of the track bed does not vary with the excitation and environment conditions, it can be used for judging the performance of the ground-borne vibration, i.e. the inherent ability to mitigate vibration, of the resilient track. Another criterion is the overall frequency-weighted root-mean-square acceleration at the receivers. This criterion is used for the estimation of the real effects of the ground-borne vibration of a resilient track in practical conditions. Calculation results demonstrate that the practical effects of ground-borne vibration of the mitigation measures studied vary with the excitation and environment factors and tend to be more effective when the unevenness excitation is rougher or the monitoring points are closer to the source of vibration. The proposed criteria, the corresponding models developed, and the methodology presented exhibit both high efficiency in computation and great convenience for assessing the mitigation measures of resilient tracks.

RESEARCH ON AIRBORNE SAR IMAGING BASED ON ESC ALGORITHM

Due to the ability of flexible, accurate, and fast obtaining abundant information, airborne SAR is significant in the field of Earth Observation and many other applications. Optimally the flight paths are straight lines, but in reality it is not the case since some portion of deviation from the ideal path is impossible to avoid. A small disturbance from the ideal line will have a major effect on the signal phase, dramatically deteriorating the quality of SAR images and data. Therefore, to get accurate echo information and radar images, it is essential to measure and compensate for nonlinear motion of antenna trajectories. By means of compensating each flying trajectory to its reference track, MOCO method corrects linear phase error and quadratic phase error caused by nonlinear antenna trajectories. Position and Orientation System (POS) data is applied to acquiring accuracy motion attitudes and spatial positions of antenna phase centre (APC). In this paper, extend chirp scaling algorithm (ECS) is used to deal with echo data of airborne SAR. An experiment is done using VV-Polarization raw data of C-band airborne SAR. The quality evaluations of compensated SAR images and uncompensated SAR images are done in the experiment. The former always performs better than the latter. After MOCO processing, azimuth ambiguity is declined, peak side lobe ratio (PSLR) effectively improves and the resolution of images is improved obviously. The result shows the validity and operability of the imaging process for airborne SAR.

AIM in-vehicle platform for ITS services

The application platform for intelligent mobility (AIM) is a large scale research infrastructure operated by the Institute of Transportation System of the German Aerospace Center (DLR) in the city and region of Braunschweig. The in-vehicle platform for ITS services (ITS, Intelligent Transportation Systems) is an integral part of this large-scale research facility. The in-vehicle platform for ITS services can be seen as a modular kit which enables up to 50 vehicles to take part in a Vehicle-to-Vehicle and Vehicle-to-Infrastructure (V2X) communications in test sites like the V2X reference track in the city of Braunschweig. The in-vehicle platform for ITS services along with its integration into the AIM test field provides answers to a broad set of research questions in the Field of V2X communications on public roads. For example effects can be analyzed, which take place when vehicles with mixed equipped communication technologies are sharing one road.

AIM reference track - test site for V2X communication systems and cooperative ITS services

Cooperative intelligent transport systems (C-ITS) based on Vehicle2X (V2X) communication are currently under development in the automotive industry and regarded to be in mass-production in the near future. In order to develop and test cooperative ITS services, the Institute of Transportation Systems of the German Aerospace Center (DLR) operates a large-scale test site in the city of Braunschweig, Germany. This research infrastructure facilitates test activities, measurements as well as evaluation activities for C-ITS in a real-life environment.

Analysis of Vehicle Lateral Response During Regenerative Braking in a Turn

Regenerative braking is applied only at the driven wheels in electric and hybrid vehicles. The presence of brake force only at the driven wheels reduces the lateral traction limit of the corresponding tires. This impacts the vehicle lateral response, particularly while applying the regenerative brake in a turn. In this paper, a detailed study was made on the impact of regenerative brake on the vehicle lateral response in front wheel drive and rear wheel drive configurations on dry and wet asphalt road surfaces. Simulations were done considering a typical set of vehicle parameters with the IPG CarMaker® software for different drive conditions and braking configurations along the same reference track. The steering wheel angle, yaw rate, lateral acceleration, vehicle slip angle, and tire forces were obtained. Further, they were compared against the conventional all wheel friction brake configuration. The regenerative braking configuration that had the most impact on vehicle lateral response was analyzed and response variations were quantified.

Statistics of Nonlinear Internal Waves during the Shallow Water 2006 Experiment

During the Shallow Water Acoustic Experiment 2006 (SW06) conducted on the New Jersey continental shelf in the summer of 2006, detailed measurements of the ocean environment were made along a fixed reference track that was parallel to the continental shelf. The time-varying environment induced by nonlinear internal waves (NLIWs) was recorded by an array of moored thermistor chains and by X-band radars from the attending research vessels. Using a mapping technique, the three-dimensional (3D) temperature field for over a month of NLIW events is reconstructed and analyzed to provide a statistical summary of important NLIW parameters, such as the NLIW propagation speed, direction, and amplitude. The results in this paper can be used as a database for studying the NLIW generation, propagation, and fidelity of nonlinear internal wave models.

Experimental characterization of thermoelectric properties of thick film composites

This paper presents thermoelectric properties of thick-film composites in relation to their potential use as power microgenerators. Several different combinations of composites were used to create thermopiles. One track of each thermocouple was made of PdAg or Pt and was the reference track and the second one of the tested material. After preliminary tests five composites with low resistance and adequate Seebeck coefficient were chosen (Ag, Ag+RuO2 and three kinds of RuO2). We measured the Thermoelectric Force, ET = f(T) and internal resistance Ri = f(T) characteristics over the temperature range 293 to 493 K. PdAg/Ag thermocouples have nearly two orders of magnitude higher output electrical power than the others. The change in values of electrical parameters of thermopiles after long-term ageing processes was also investigated.

Track-Following Controller Design for a Compound Disk Drive Actuator

The use of compound actuators in both magnetic and optical disk files has become a means of achieving increased servo actuator bandwidths. A compound actuator, comprised of a fine actuator mounted “piggyback” on a coarse actuator, positions the read/write transducers above a radial track. This paper describes a design methodology for a discrete-time feedback control system for a compound actuator in which the dynamic interaction between the actuator stages is directly considered. The performance of the servosystem, including the range and bandwith limitations of each actuator, is specified in terms of the desired frequency response of the closed-loop transfer functions from the reference track position to the tracking error and to the relative position between the coarse and the fine actuator. Parameter uncertainties and structural resonances are quantified using singular value techniques to form a robustness criterion which sets limits on the attainable tracking performance. Compensator design techniques using linear-quadratic Gaussian optimal control combined with loop transfer recovery are described. The state feedback portion of the compensator is calculated using an automatic procedure, while the state estimator is calculated by solving an associated Kalman filtering problem with colored fictitious noise. The noise is colored to shape the frequency spectrum of the input energy to each actuator, the relative motion between the stages, and the position of the transducer.