High Update Research Articles

Applied Technology in Data Evaluation and Position Quality of ADS-B System

Automatic dependent surveillance-broadcast (ADS-B) is a totally new surveillance method, so before practically applied and operated in China, abundant tests and evaluations are necessary to validate the performance of ADS-B and guarantee the operational security. To solve the asynchronous problem among radar data, ADS-B data and real-time kinematic (RTK) data caused by different update rates, this paper proposes the technique of synchronizing multi-surveillance data by extrapolating from the data of low update rate to high update rate according to velocity and heading. Meanwhile, because radar data, ADS-B data and RTK data are expressed in different coordinates and cannot be compared each other, this article provides a method to unifying the coordinates of multi-surveillance data. By the analysis and evaluation, we can conclude that the performance of ADS-B is better than radar. Addtionally, the paper makes focus study on the position quality indicator and the encoding rules, and puts forward the conversion between the different rules. The paper provides the technical guide for the manufacturers and the airlines.

Precision Bounds of Pavement Deterioration Forecasts from Connected Vehicles

Transportation agencies rely on models to predict when pavements will deteriorate to a condition or ride-index threshold that triggers maintenance actions. The accuracy and precision of such forecasts are directly proportional to the frequency of monitoring. Ride indices derived from connected vehicle sensor data will enable transformational gains in both the accuracy and precision of deterioration forecasts because of very high data volume and update rates. This analysis develops theoretical precision bounds for a ride index called the road impact factor and demonstrates, via a case study, its relationship with vehicle suspension parameter variances.

Warped time lens in temporal imaging for optical real-time data compression

We introduce for the first time the concept of anamorphic temporal imaging and its application to analog data compression in a time lens. Placed in front of a conventional spectrometer, this technique enhances the spectral resolution and the update rate. More importantly, it performs real-time optical data compression to reduce the volume of the generated digital data. Our technique introduces the concept of the warped time lens. We show that a specific class of warped time-to-frequency mapping operations combined with the nonlinear operation inherent in a photo-detector compresses the time-bandwidth product in a temporal imaging system. We employ our newly introduced Stretched Modulation Distribution to design the warp profile. Using this method, the narrow spectral features beyond the spectrometer resolution can be captured and at the same time the output bandwidth and hence the record length is minimized. The reduction in the record length results in higher update rate for the spectrometer without sacrificing the spectral resolution or bandwidth. Our method also benefits from amplitude and phase detection to recover the input complex-field spectrum. By compressing the time-bandwidth product, anamorphic temporal imaging addresses the Big Data problem in such high-throughput instruments.

Polyharmonic Digital Synthesizer for the Calibration of Phase Sensitive Measuring Systems Up to the Ultrasonic Band

A double output digital polyharmonic synthesizer suitable for the calibration of phase sensitive measuring systems and harmonics in power analyzers is being developed at INRIM. Digital-to-analog converters with high resolution and update rate simultaneously synthesize a pair of waveforms with fine trimming of electric parameters and harmonics. Its bandwidth is up to 100 MHz, verified with a wideband sampling oscilloscope, and the frequency resolution is 20 MHz in the whole bandwidth. The synthesizer has been characterized in terms of amplitude, accuracy, and stability up to 1 MHz by means of a programmable ac/dc transfer standard. For frequencies up to 100 kHz, a calibrated precision digitizer, configured as a phase comparator, is used for its characterization. The measured phase offset and noise at 20 kHz are 5 $\mu{\rm rad}$ and 300 nrad, respectively. The same digitizer has been used for the precise measure of the harmonic spurs up to 100 kHz. Instead, for the evaluation of the total harmonic distortion from 100 kHz up to 50 MHz, a wideband spectrum analyzer has been used. The algorithms employed allow the use of the synthesizer as a digital phase standard or as a polyharmonic arbitrary synthesizer with independent outputs.

AUTOMATIC FEATURE-BASED POINT CLOUD REGISTRATION FOR A MOVING SENSOR PLATFORM

Abstract. The automatic and accurate alignment of multiple point clouds is a basic requirement for an adequate digitization, reconstruction and interpretation of large 3D environments. Due to the recent technological advancements, modern devices are available which allow for simultaneously capturing intensity and range images with high update rates. Hence, such devices can even be used for dynamic scene analysis and for rapid mapping which is particularly required for environmental applications and disaster management, but unfortunately, they also reveal severe restrictions. Facing challenges with respect to noisy range measurements, a limited non-ambiguous range, a limited field of view and the occurrence of scene dynamics, the adequate alignment of captured point clouds has to satisfy additional constraints compared to the classical registration of terrestrial laser scanning (TLS) point clouds for describing static scenes. In this paper, we propose a new methodology for point cloud registration which considers such constraints while maintaining the fundamental properties of high accuracy and low computational effort without relying on a good initial alignment or human interaction. Exploiting 2D image features and 2D/2D correspondences, sparse point clouds of physically almost identical 3D points are derived. Subsequently, these point clouds are aligned with a fast procedure directly taking into account the reliability of the detected correspondences with respect to geometric and radiometric information. The proposed methodology is evaluated and its performance is demonstrated for data captured with a moving sensor platform which has been designed for monitoring from low altitudes. Due to the provided reliability and a fast processing scheme, the proposed methodology offers a high potential for dynamic scene capture and analysis.

Parametric Content-Based Publish/Subscribe

Content-based publish/subscribe (CPS) is an appealing abstraction for building scalable distributed systems, e.g., message boards, intrusion detectors, or algorithmic stock trading platforms. Recently, CPS extensions have been proposed for location-based services like vehicular networks, mobile social networking, and so on. Although current CPS middleware systems are dynamic in the way they support the joining and leaving of publishers and subscribers, they fall short in supporting subscription adaptations. These are becoming increasingly important across many CPS applications. In algorithmic high frequency trading, for instance, stock price thresholds that are of interest to a trader change rapidly, and gains directly hinge on the reaction time to relevant fluctuations rather than fixed values. In location-aware applications, a subscription is a function of the subscriber location (e.g. GPS coordinates), which inherently changes during motion. The common solution for adapting a subscription consists of a resubscription, where a new subscription is issued and the superseded one canceled. This incurs substantial overhead in CPS middleware systems, and leads to missed or duplicated events during the transition. In this article, we explore the concept of parametric subscriptions for capturing subscription adaptations. We discuss desirable and feasible guarantees for corresponding support, and propose novel algorithms for updating routing mechanisms effectively and efficiently in classic decentralized CPS broker overlay networks. Compared to resubscriptions, our algorithms significantly improve the reaction time to subscription updates without hampering throughput or latency under high update rates. We also propose and evaluate approximation techniques to detect and mitigate pathological cases of high frequency subscription oscillations, which could significantly decrease the throughput of CPS systems thereby affecting other subscribers. We analyze the benefits of our support through implementations of our algorithms in two CPS systems, and by evaluating our algorithms on two different application scenarios.

WLAN Location Service with TXOP

The provision of location-based services with high positional accuracy requires the use of Time of Arrival (TOA)-based techniques. However, existing TOA-based WLAN location service schemes are inefficient due to the individual query and response ranging method employed. We present a highly efficient WLAN location service architecture which includes a modification to the Transmit Opportunity (TXOP) technique in the IEEE 802.11e standard. Our Location Service with TXOP (LSOP) scheme achieves high efficiency by minimizing the number of TOA transmissions and eliminating the contention overhead for TOA messages. The adaptation of TXOP technique also improves location accuracy by protecting TOA messages from collision and by grouping the TOA messages into one compact burst. Our analysis shows that the LSOP scheme achieves the highest location update rate compared to previous schemes. Our simulation results show that the LSOP scheme has minimum impact on data traffic and achieves higher accuracy than the previous schemes. Experimental results demonstrate the degradation in localization performance caused by packet collisions. These results validate that our LSOP scheme, which implements contention-free broadcast of TOA messages with a modified TXOP, provides the best combination of high location update rate, low network load, and high location accuracy compared to other schemes.

Characterization of a Flexible UWB Sensor for Indoor Localization

This paper presents research to develop an ultrawideband ranging sensor for personnel indoor localization based on the measurement of the pulse round-trip time. An approach combining flexibility, a high measurement update rate, and asynchronous operation with digital processing capability has been employed in the design of the sensor. The principle of operation, the architecture of the realized sensor, and the experimental setup are described. Finally, the results of a ranging calibration and validation test are presented and discussed. In the validation procedure, a root-mean-square error of 29 cm and a maximum absolute error of 81 cm with an operational range of approximately 10 m were observed.

Robotic goalie with 3 ms reaction time at 4% CPU load using event-based dynamic vision sensor

Conventional vision-based robotic systems that must operate quickly require high video frame rates and consequently high computational costs. Visual response latencies are lower-bound by the frame period, e.g., 20 ms for 50 Hz frame rate. This paper shows how an asynchronous neuromorphic dynamic vision sensor (DVS) silicon retina is used to build a fast self-calibrating robotic goalie, which offers high update rates and low latency at low CPU load. Independent and asynchronous per pixel illumination change events from the DVS signify moving objects and are used in software to track multiple balls. Motor actions to block the most “threatening” ball are based on measured ball positions and velocities. The goalie also sees its single-axis goalie arm and calibrates the motor output map during idle periods so that it can plan open-loop arm movements to desired visual locations. Blocking capability is about 80% for balls shot from 1 m from the goal even with the fastest-shots, and approaches 100% accuracy when the ball does not beat the limits of the servo motor to move the arm to the necessary position in time. Running with standard USB buses under a standard preemptive multitasking operating system (Windows), the goalie robot achieves median update rates of 550 Hz, with latencies of 2.2 ± 2 ms from ball movement to motor command at a peak CPU load of less than 4%. Practical observations and measurements of USB device latency are provided1.

Flight Evaluation of a Locata-augmented Multisensor Navigation System

The Global Navigation Satellite System (GNSS) is a widely used technology for high accuracy positioning in support of many applications, including airborne mapping and sensor georeferencing. The integration of GNSS and an Inertial Navigation System (INS) is a critical navigation component in an airborne mapping system, because it can provide high update rate of solutions, platform attitude information and improved performance (e.g. accuracy, availability). However, GNSS signals can be easily blocked or interfered with, and sometimes the satellite geometry may not be good enough for high accuracy and high reliability applications. Therefore the development of alternative, non-GNSS-based navigation solutions has attracted increased interest in situations where GNSS system availability cannot be guaranteed. Locata is a groundbased navigation system which can transmit ranging signals at several frequencies in the 2.4 GHz Industrial, Scientific and Medical radio bands. Tracking of Locata signals allows additional range-like measurements to be made, which can be processed in a manner not unlike GNSS measurements. Hence the integration of GNSS, INS and Locata can address requirements for seamless precise positioning in many situations. This paper describes a flight test of a GPS+INS+Locata triple-integrated system. The test was conducted in October 2011, during a flight from Bankstown Airport, Sydney, to Cooma Snowy Mountains Airport. The Locata pseudorange measurements were collected and postprocessed to evaluate overall navigation performance and to investigate the limitations of such an integrated system.

VLSI implementation of star detection and centroid calculation algorithms for star tracking applications

Nowadays, hardware implementation of image and video processing algorithms on application specific integrated circuit (ASIC) has become a viable target in many applications. Star tracking algorithm is commonly used in space missions to recover the attitude of the satellite or spaceship. The algorithm matches stars of the satellite camera with the stars in a catalog to calculate the camera orientation (attitude). The number of stars in the catalog has the major impact on the accuracy of the star tracking algorithm. However, the higher number of stars in the catalog increases the computation burden and decreases the update rate of the algorithm. Hardware implementation of the star tracking algorithm using parallel and pipelined architecture is a proper solution to ensure higher accuracy as well as higher update rate. Noise filtering and also the detection of stars and their centroids in the camera image are the main stages in most of the star tracking algorithms. In this paper, we propose a new hardware architecture for star detection and centroid calculation in star tracking applications. The method contains several stages, including noise smoothing with fast Gaussian and median filters, connected component labeling, and centroid calculation. We introduce a new and fast algorithm for star labeling and centroid calculation that needs only one scan of the input image.

Accurate Wireless Localization in Sports

The wireless ad hoc system for positioning (WASP) provides high accuracy and high update rates when used for performance monitoring in elite sports training, where using real-time location and physiological information helps improve athletic performance.

Asynchronous Event-Based Visual Shape Tracking for Stable Haptic Feedback in Microrobotics

Micromanipulation systems have recently been receiving increased attention. Teleoperated or automated micromanipulation is a challenging task due to the need for high-frequency position or force feedback to guarantee stability. In addition, the integration of sensors within micromanipulation platforms is complex. Vision is a commonly used solution for sensing; unfortunately, the update rate of the frame-based acquisition process of current available cameras cannot ensure-at reasonable costs-stable automated or teleoperated control at the microscale level, where low inertia produces highly unreachable dynamic phenomena. This paper presents a novel vision-based microrobotic system combining both an asynchronous address event representation silicon retina and a conventional frame-based camera. Unlike frame-based cameras, recent artificial retinas transmit their outputs as a continuous stream of asynchronous temporal events in a manner similar to the output cells of a biological retina, enabling high update rates. This paper introduces an event-based iterative closest point algorithm to track a microgripper's position at a frequency of 4 kHz. The temporal precision of the asynchronous silicon retina is used to provide a haptic feedback to assist users during manipulation tasks, whereas the frame-based camera is used to retrieve the position of the object that must be manipulated. This paper presents the results of an experiment on teleoperating a sphere of diameter around 50 μm using a piezoelectric gripper in a pick-and-place task.

Foster b-trees

Foster B-trees are a new variant of B-trees that combines advantages of prior B-tree variants optimized for many-core processors and modern memory hierarchies with flash storage and nonvolatile memory. Specific goals include: (i) minimal concurrency control requirements for the data structure, (ii) efficient migration of nodes to new storage locations, and (iii) support for continuous and comprehensive self-testing. Like B link -trees, Foster B-trees optimize latching without imposing restrictions or specific designs on transactional locking, for example, key range locking. Like write-optimized B-trees, and unlike B link -trees, Foster B-trees enable large writes on RAID and flash devices as well as wear leveling and efficient defragmentation. Finally, they support continuous and inexpensive yet comprehensive verification of all invariants, including all cross-node invariants of the B-tree structure. An implementation and a performance evaluation show that the Foster B-tree supports high concurrency and high update rates without compromising consistency, correctness, or read performance.

High-Accuracy Reference-Free Ultrasonic Location Estimation

This paper presents a novel reference-free ultrasonic indoor location system. Unlike most previous proposals, the mobile device (MD) determines its own position based only on ultrasonic signals received at a compact sensor array and sent by a fixed independent beacon. No radio frequency or wired timing reference signal is used. Furthermore, the system is privacy aware and one way in that the receive-only MD determines its own position based on ultrasonic signals received from fixed transmit-only beacons. The MD uses a novel hybrid angle of arrival (AoA)-time of flight (ToF) with timing lock algorithm to determine its location relative to the beacons with high accuracy. The algorithm utilizes an AoA-based location method to obtain an initial estimate of its own location. Based on this, it estimates the timing offsets (TOs) between the MD clock and the beacon transmissions. The average TO and the known periodicities of the beacon signals are then used to obtain a second more accurate MD location estimate via a ToF method. The system utilizes wideband spread spectrum ultrasonic signaling in order to achieve a high update rate and robustness to noise and reverberation. A prototype system was constructed, and the algorithm was implemented in software. The experimental results show that the method provides 3-D accuracy better than 9.5 cm in 99% of cases, an 80% accuracy improvement over the conventional AoA-only method.

Stable Haptic Rendering Using a Pipelined Threading Architecture

The high force update rate is a key factor for achieving high performance of haptic rendering, which imposes a stringent real-time requirement upon the execution environment of the haptic system. To fulfil this requirement, haptic systems are often limited to simplified virtual environments (VEs) for reducing computational load. This paper presents a novel pipelined threading architecture, which uses several threads running consecutively for implementing haptic rendering algorithms. With the proposed method, the haptic forces updating rate is effectively increased, which leads to improved system performance and makes complex VE scenes possible in haptic rendering. Based on the 3-DOF Delta haptic device, experiments with a virtual wall haptic system are carried out and verify the proposed method.

A haptics-based virtual simulation system for product design

This paper aims to develop a haptics-based virtual simulation system for product design. To fully reach the potential of such a system, the modelling methods of the user-product interaction should be based on physics to enable users to feel the physical behaviours of various products. The key challenge is the balance between the heavy computational load and the high update rate for haptic feedback. In this paper, the modelling of rigid and deformable objects for haptics-based simulations is developed, including button click and vibration feeling as well as the interaction with heterogeneous deformable material. The commercial haptic device PHANToM Desktop from SensAble Technologies is integrated with the models into the implemented prototype system. It is validated that the proposed simulation system can allow users to experience and manipulate virtual objects in cyber space. The simulation results demonstrate that the proposed modelling methods are computationally efficient to provide real-time haptic feedback.

Integrated GPS/INS navigation system with dual-rate Kalman Filter

A dual-rate Kalman Filter (DRKF) has been developed to integrate the time-differenced GPS carrier phases and the GPS pseudoranges with INS measurements. The time-differenced GPS carrier phases, which have low noise and millimeter measurement precision, are integrated with INS measurements using a Kalman Filter with high update rates to improve the performance of the integrated system. Since the time-differenced GPS carrier phases are only relative measurements, when integrated with INS, the position error of the integrated system will accumulate over time. Therefore, the GPS pseudoranges are also incorporated into the integrated system using a Kalman Filter with a low update rate to control the accumulation of system errors. Experimental tests have shown that this design, compared to a conventional design using a single Kalman Filter, reduces the coasting error by two-thirds for a medium coasting time of 30 s, and the position, velocity, and attitude errors by at least one-half for a 45-min field navigation experiment.

Multirate Energy-Bounding Algorithm for High-Fidelity Stable Haptic Interaction Control

This brief describes a multirate energy-bounding algorithm that significantly increases the displayable stiffness while guaranteeing the overall haptic interaction stability. Unlike haptic interaction control algorithms that are based on the multirate simulation of virtual environments, the proposed multirate approach separates the low-level control thread from the haptic thread. The haptic thread updates the haptic interaction computation, or the collision detection and response and dynamic or deformation simulation, of a virtual environment at slow rate while the low-level control thread updates the actuator command force determined by the energy-bounding algorithm to guarantee the interaction stability at a high update rate. An analytical derivation study shows that the displayable stiffness of virtual environments can be significantly increased by an order of N, which is the ratio of the fast actuator command signal update to the slow haptic simulation update. Experiments using a commercial haptic device demonstrate that the displayed stiffness significantly increases while guaranteeing stability even when the haptic rendering rate is slow.

Multisensor Data Fusion in an Integrated Tracking System for Endoscopic Surgery

Surgical planning and navigation systems are vital for minimally invasive endoscopic surgeries but it is challenging to track the position and orientation of intrabody surgical instruments in these procedures. In order to address this problem, we propose a tracking system including multiple-sensor integration and data fusion. The proposed tracking approach is free of the constraints of line-of-sight, less subject to environmental distortion, and with higher update rate. By incorporating electromagnetic and inertial sensors, the system yields continuous 6-DOF information. Based on a system dynamic model and estimation theories, a new multisensor fusion algorithm, cascade orientation and position-estimation algorithm, is proposed for the integrated tracking device. The experimental results show that the proposed algorithms achieve accurate orientation and position tracking with robustness.