Multi‐viewer autostereoscopic display with dynamically addressable holographic backlight

Abstract— The Multi‐User 3‐D Television Display (MUTED), designed to provide three‐dimensional television (3‐D TV) by the display of autostereoscopic imagery to multiple viewers, each of whom should enjoy freedom of movement, is described. Such an autostereoscopic display system, which allows multiple viewers simultaneously by the use of head tracking, was previously demonstrated for TV applications in the ATTEST project. However, the requirement for a dynamically addressable, steerable backlight presented several problems for the illumination source. The MUTED system demonstrates significant advances in the realization of a multi‐user autostereoscopic display, partly due to the provision of a dynamic backlight employing a novel holographic laser projector. Such a technology provides significant advantages in terms of brightness, efficiency, laser speckle, and the ability to correct for optical aberrations compared to both imaging and scanned‐beam projection technologies.     

Reconstructing 3D human models with a Kinect

Three‐dimensional human model reconstruction has wide applications due to the rapid development of computer vision. The appearance of cheap depth camera, such as Kinect, opens up new horizons for home‐oriented 3D human reconstructions. However, the resolution of Kinect is relatively low, making it difficult to build accurate human models. In this paper, we improve the accuracy of human model reconstruction from two aspects. First, we improve the depth data quality by registering the depth images captured from multi‐views with a single Kinect. The part‐wise registration method and implicit‐surface‐based de‐noising method are proposed. Second, we utilize a statistical human model to iteratively augment and complete the human body information by fitting the statistical human model to the registered depth image. Experimental results and several applications demonstrate the applicability and quality of our system, which can be potentially used in virtual try‐on systems. Copyright © 2015 John Wiley & Sons, Ltd.     

Further on the controllability of networked MIMO LTI systems

Further on the controllability of networked multiple‐input–multiple‐output systems, an efficient, necessary, and sufficient condition is derived, where the network topology is directed and weighted and the nodes are higher‐dimensional linear time‐invariant systems. The new condition is easier to verify, which explicitly shows the effects of the network topology, node‐system dynamics, external control inputs, and inner interactions on the controllability of the whole networked system. For networked multiple‐input–multiple‐output systems in several specific topologies, the corresponding conditions are expressed more precisely. The effectiveness of the conditions is demonstrated through several examples.     

Real time egomotion of a nonholonomic vehicle using LIDAR measurements

This paper presents a technique to estimate in real time the egomotion of a vehicle based solely on laser range data. This technique calculates the discrepancy between closely spaced two‐dimensional laser scans due to the vehicle motion using scan matching techniques. The result of the scan alignment is converted into a nonlinear motion measurement and fed into a nonholonomic extended Kalman filter model. This model better approximates the real motion of the vehicle when compared to more simplistic models, thus improving performance and immunity to outliers. The motion estimate is intended to be used for egomotion compensation in a target‐tracking algorithm for situation awareness applications. In this paper, several recent scan matching algorithms were evaluated for their accuracy and computational speed: metric‐based iterative closest point (MbICP), point‐to‐line ICP (PIICP), and polar scan matching. The proposed approach is performed in real time and provides an accurate estimate of the current robot motion. The MbICP algorithm proved to be the most advantageous scan matching algorithm, but it is still comparable to PlICP. The motion estimation algorithm is validated through experimental testing in real world conditions.     

Formation control of rigid graphs with flex edges

This paper studies a distance‐based formation control problem of multiagent systems, in which each agent uses only relative positions of its neighbors with respect to its own coordinate system. First, we provide an analysis for the properties of the undesired equilibria‐corresponding 2 specific formations, ie, a triangle group in 2‐dimensional space and a tetrahedron group in 3‐dimensional space. Then, we consider the formation of multiagent systems whose interaction graph consists of a rigid group and an extra node. Although the extra node may have an additional control input, the desired formation where all interagent distance constraints are satisfied is asymptotically stable. If the rigid group is a triangle in 2‐dimensional space or a tetrahedron in 3‐dimensional space, any undesired equilibrium is unstable. In these cases, the desired formations are almost globally asymptotically stable. Finally, we extend these results to a more general formation, which is a series of rigid groups connecting via flex edges.     

IQC‐based robustness analysis of discrete‐time linear time‐varying systems

The paper investigates the robust stability and performance of uncertain linear time‐varying (LTV) systems using an integral quadratic constraint (IQC) based analysis approach. Specifically, previous theoretical work on IQC‐based robustness analysis of linear time‐invariant (LTI) systems is extended to discrete‐time LTV systems. In the case of a general LTV nominal system, the analysis solution is provided in terms of an infinite‐dimensional convex optimization problem. This optimization problem reduces into a finite‐dimensional semidefinite program when the nominal system in question is finite horizon, periodic, or, more generally, eventually periodic. Finally, the results are applied to an unmanned aircraft control system executing an aggressive maneuver, where the developed techniques are used to find the region in which the aircraft is guaranteed to reside at the end of its planned trajectory. Copyright © 2017 John Wiley & Sons, Ltd.     

Browsing large‐scale cheminformatics data with dimension reduction

Visualization of large‐scale high dimensional data is highly valuable for data analysis facilitating scientific discovery in many fields. We present PubChemBrowse, a customized visualization tool for cheminformatics research. It provides a novel 3D data point browser that displays complex properties of massive data on commodity clients. As in Geographic Information System browsers for Earth and Environment data, chemical compounds with similar properties are nearby in the browser. PubChemBrowse is built around in‐house high performance parallel Multi‐dimensional scaling and Generative topographic mapping services and supports fast interaction with an external property database. These properties can be overlaid on 3D mapped compound space or queried for individual points. We prototype the integration with Chem2Bio2RDF system using SPARQL endpoint to access over 20 publicly accessible bioinformatics databases. We describe our design and implementation of the integrated PubChemBrowse application and outline its use in drug discovery. The same core technologies are generally applicable to develop high performance scientific data browsing systems for other applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Invited Paper: The evolution of projection displays: From mechanical scanners to microdisplays

Abstract— The development of electronic projection systems from its earliest days in the 1930s to the present will be reviewed. Early projection systems were dominated by cathode‐ray tubes (CRTs) and mechanical scanners (Scophony). Until the invention of the Eidophor oil‐film light‐valve (LV) projector in the 1940s, there was no all‐electronic alternative to CRTs. Oil‐film LVs and CRTs dominated projection until the introduction of the first liquid‐crystal‐device (LCD) light‐amplifier system by Hughes. Today, the oil‐film LV has vanished and the CRT is vanishing. The light amplifier has morphed into several variations of liquid crystal‐on‐silicon (LCoS). Mechanical scanners are starting to be re‐introduced for laser display systems. However, transmissive LCDs, the digital micromirror device (DMD), and LCoS microdisplays dominate the projection‐display market today. In addition to discussing the projection systems themselves, certain key component technologies that have made modern projection systems possible will be discussed.     

Regional output feedback stabilization of semilinear time‐fractional diffusion systems in a parallelepipedon with control constraints

This article is concerned with the regional output feedback stabilization problems for semilinear time‐fractional diffusion systems in a 1≤n?dimensional parallelepipedon with control inequality constraints. For this, the spectrum decomposition method is used to derive a finite‐dimensional fractional ordinary differential equation (ODE) system that captures the dominant dynamics of the considered system. With this ODE system, we propose a finite‐dimensional fractional compensator to guarantee that the constrained closed‐loop semilinear systems are Mittag‐Leffler stable in some subregions of their evolution domains. An example is finally included to illustrate our results.     

Visual Analysis of Trajectories in Multi‐Dimensional State Spaces

Multi‐dimensional data originate from many different sources and are relevant for many applications. One specific sub‐type of such data is continuous trajectory data in multi‐dimensional state spaces of complex systems. We adapt the concept of spatially continuous scatterplots and spatially continuous parallel coordinate plots to such trajectory data, leading to continuous‐time scatterplots and continuous‐time parallel coordinates. Together with a temporal heat map representation, we design coordinated views for visual analysis and interactive exploration. We demonstrate the usefulness of our visualization approach for three case studies that cover examples of complex dynamic systems: cyber‐physical systems consisting of heterogeneous sensors and actuators networks (the collection of time‐dependent sensor network data of an exemplary smart home environment), the dynamics of robot arm movement and motion characteristics of humanoids.     

Automated Testing of Physical Security: Red Teaming Through Machine Learning

Modern surveillance systems for practical applications with diverse and mobile sensors are large, complex, and expensive. It is known that unexpected behaviors can emerge from such systems, and when these behaviors correspond to weaknesses in a surveillance system, we call them emergent vulnerabilities. Given their cost and importance to security, it is essential to test these systems for such vulnerabilities prior to deployment. To that end, we automate the testing process with multiagent systems and machine learning. However, the conventional—and most intuitive–approach is to focus the machine learning on the subject system, which leads to a high‐dimensional problem that is intractable. Instead, we demonstrate in this paper that learning attacks on the system is tractable and provides a viable testing method. We demonstrate this with a series of studies in simulation and with a small‐scale model system featuring elements typically found in real physical surveillance systems. Our machine learning method finds successful attacks in simulation, which we can duplicate with the physical system. The method is scalable, with the implication that it could be used to test larger, real surveillance installations.     

Dynamic Output Feedback Consensualization of Uncertain Swarm Systems with Time Delays

Consensus analysis and design problems of high‐dimensional discrete‐time swarm systems in directed networks with time delays and uncertainties are dealt with by using output information. Two subspaces are introduced, namely a consensus subspace and a complement consensus subspace. By projecting the state of a swarm system onto the two subspaces, a necessary and sufficient condition for consensus is presented, and based on different influences of time delays and uncertainties, an explicit expression of the consensus function is given which is very important in applications of swarm systems. A method to determine gain matrices of consensus protocols is proposed. Numerical simulations are presented to demonstrate theoretical results.     

Output‐based disturbance rejection control for 1‐D anti‐stable Schrödinger equation with boundary input matched unknown disturbance

In this paper, we are concerned with the output feedback control design for a system (plant) described by a boundary controlled anti‐stable one‐dimensional Schrödinger equation. Our output measure signals are the displacements at both side. An untraditional infinite‐dimensional disturbance estimator is developed to estimate the disturbance. Based on the estimator, we propose a state observer that is exponentially convergent to the original system and then design a stabilizing control law consisting of two parts: The first part is to compensate the disturbance by using its approximated value and the second part is to stabilize the observer system by applying the classical backstepping approach. The resulting closed‐loop system is shown to be exponentially stable with guaranteeing that all internal systems are uniformly bounded. An effective output‐based disturbance rejection control algorithm is concluded. An application, namely, a cascade of ODE–wave systems, is investigated by the developed control algorithm. Numerical experiments are carried out to illustrate the effectiveness of the proposed control law. Copyright © 2017 John Wiley & Sons, Ltd.     

Continuous‐Time Three‐Dimensional Mapping for Micro Aerial Vehicles with a Passively Actuated Rotating Laser Scanner

The ability to generate accurate and detailed three‐dimensional (3D) maps of a scene from a mobile platform is an essential technology for a wide variety of applications from robotic navigation to geological surveying. In many instances, the best vantage point is from above, and as a result, there is a growing demand for low‐altitude mapping solutions from micro aerial vehicles such as small quadcopters. Existing lidar‐based 3D airborne mapping solutions rely on GPS/INS solutions for positioning, or focus on producing relatively low‐fidelity or locally focused maps for the purposes of autonomous navigation. We have developed a general‐purpose airborne 3D mapping system capable of continuously scanning the environment during flight to produce accurate and dense point clouds without the need for a separate positioning system. A key feature of the system is a novel passively driven mechanism to rotate a lightweight 2D laser scanner using the rotor downdraft from a quadcopter. The data generated from the spinning laser is input into a continuous‐time simultaneous localization and mapping (SLAM) solution to produce an accurate 6 degree‐of‐freedom trajectory estimate and a 3D point cloud map. Extensive results are presented illustrating the versatility of the platform in a variety of environments including forests, caves, mines, heritage sites, and industrial facilities. Comparison with conventional surveying methods and equipment demonstrates the high accuracy and precision of the proposed solution.     

Multiprocessor platform for partitioned real‐time systems

Two current trends in the real‐time and embedded systems are the multiprocessor architectures and the partitioning technology that enables several isolated applications with different criticality levels to share the same computer. This paper presents a real‐time platform for multiprocessor and partitioned systems, in which communication requirements are also considered. The paper describes the adaptation of MaRTE OS (a monoprocessor real‐time operating system) to the XtratuM hypervisor for the multiprocessor Intel x86 architecture. This adaptation makes two contributions to ease the development process of future mixed‐criticality applications: firstly, it integrates the hypervisor technology and the fully partitioned scheduling in a multiprocessor environment, and secondly, it provides the basis to interconnect partitioned and non‐partitioned applications via a homogeneous communication subsystem. Copyright © 2016 John Wiley & Sons, Ltd.     

Jgroup/ARM: a distributed object group platform with autonomous replication management

This paper presents the design and implementation of Jgroup/ARM, a distributed object group platform with autonomous replication management along with a novel measurement‐based assessment technique that is used to validate the fault‐handling capability of Jgroup/ARM. Jgroup extends Java RMI through the group communication paradigm and has been designed specifically for application support in partitionable systems. ARM aims at improving the dependability characteristics of systems through a fault‐treatment mechanism. Hence, ARM focuses on deployment and operational aspects, where the gain in terms of improved dependability is likely to be the greatest. The main objective of ARM is to localize failures and to reconfigure the system according to application‐specific dependability requirements. Combining Jgroup and ARM can significantly reduce the effort necessary for developing, deploying and managing dependable, partition‐aware applications. Jgroup/ARM is evaluated experimentally to validate its fault‐handling capability; the recovery performance of a system deployed in a wide area network is evaluated. In this experiment multiple nearly coincident reachability changes are injected to emulate network partitions separating the service replicas. The results show that Jgroup/ARM is able to recover applications to their initial state in several realistic failure scenarios, including multiple, concurrent network partitionings. Copyright © 2007 John Wiley & Sons, Ltd.     

Complete controllability for abstract measure differential systems

In this paper, we investigate the complete controllability for abstract measure differential systems. Firstly, we introduce several new concepts about complete controllability for abstract measure differential systems. Then, on the basis of the Sadovskii fixed‐point theorem, we give sufficient conditions for complete controllability for a class of abstract measure differential systems. The compactness of the semigroup generated by some operator is unnecessary in this paper, and we show that our results, dealing with complete controllability problem for an ordinary differential system in infinite‐dimensional Banach space, are also less conservative than that in the previous literature. Copyright © 2012 John Wiley & Sons, Ltd.     

Formulation of dynamics,actuation, and inversion of a three‐dimensional two‐link rigid body system

In this paper, three issues related to three‐dimensional multilink rigid body systems are considered: dynamics, actuation, and inversion. Based on the Newton‐Euler equations, a state space formulation of the dynamics is discussed that renders itself to inclusion of actuators, and allows systematic ways of stabilization and construction of inverse systems. The development here is relevant to robotic systems, biological modeling, humanoid studies, and collaborating man‐machine systems. The recursive dynamic formulation involves a method for sequential measurement and estimation of joint forces and couples for an open chain system. The sequence can start from top downwards or from the ground upwards. Three‐dimensional actuators that produce couples at the joints are included in the dynamics. Inverse methods that allow estimation of these couples from the kinematic trajectories and physical parameters of the system are developed. The formulation and derivations are carried out for a two‐link system. Digital computer simulations of a two‐rigid body system are presented to demonstrate the feasibility and effectiveness of the methods. © 2005 Wiley Periodicals, Inc.     

Energy‐efficient task allocation with quality of service provisioning for concurrent applications in multi‐functional wireless sensor network systems

Multi‐functional wireless sensor network (WSN) system is a new design trend of WSNs, which are evolving from dedicated application‐specific systems to an integrated infrastructure that supports the execution of multiple concurrent applications. Such system offers inherent advantages in terms of cost and flexibility because it allows the effective utilization of available sensors and resource sharing among multiple applications. However, sensor nodes are very constrained in resources, mainly regarding their energy. Therefore, the usage of such resources needs to be carefully managed, and the sharing with several applications imposes new challenges in achieving energy efficiency in these networks. In order to exploit the full potential of multi‐functional WSN systems, it is crucial to design mechanisms that effectively allocate tasks onto sensors so that the entire system lifetime is maximized while meeting various application requirements. However, it is likely that the requirements of different applications cannot be simultaneously met. In this paper, we present the Multi‐Application Requirements Aware and Energy Efficiency algorithm as a new resource allocation heuristic for multi‐functional WSN system to maximize system lifetime subject to various application requirements. The heuristic effectively deals with different quality of service parameters (possibly conflicting) trading those parameters and exploiting heterogeneity of multiple WSNs. Copyright © 2013 John Wiley & Sons, Ltd.