Search

In order to deploy multi-robot into a 2-D desired formation during the seeking process, this paper proposes a hybrid seeking algorithm with the formation deployment. Firstly, this paper expands the 1-D deployment algorithm to 2-D, and then combines with the extreme seeking algorithm to obtain the hybrid seeking algorithm. With the algorithm, multi-robot can deploy into a desired 2-D formation during seeking process. Simulation results are provided to illustrate the effectiveness of the algorithm.

A new class of double nearest-neighbor errorcorrecting codes on hexagonal constellation in the two dimensional space is presented. The proposed code is a linear [n,n−3] code over GF(p) where p = 6n+1 is a prime. We show that the proposed code corrects any generalized Lee error with at most weight 2.

The coverage control problem for robotic networks focuses on distributively coordinating the positioning of multiple dynamic agents to provide sensor coverage across a bounded region in two dimensional space. The associated optimal coverage problem seeks to position these agents so as to minimize an associated coverage cost. This coverage cost is typically defined with respect to a density function that is used to bias the network towards desired configurations. Previous approaches to this optimal coverage problem have addressed both static and dynamic environments through the choice of density function; however, stability guarantees for time-varying densities are restricted by significant technical assumptions that simplify the underlying proofs at the expense of limited applicability. In this paper, a generalized algorithm is presented that guarantees practical stability under relaxed technical assumptions. The algorithm, and its convergence, is illustrated via simulation examples.

With the increase of Internet of Things (IoT) applications, indoor positioning systems have begun to gain importance. Since there is no widespread technique in this area like Global Positioning System (GPS) at outdoors, a vast variety of techniques and technologies are being used in indoor positioning. Triangulation is one of the most frequently used techniques which can be categorized into two techniques: lateration and angulation. Lateration technique uses distance information in the estimation of location while the angulation technique uses angles besides distances. The lateration technique is called as trilateration when it is applied in two dimensional space. In this paper, trilateration technique is analyzed where one of the reference points resides of an uncertain location. The location of an object is estimated as an area by using two certain reference points. The proposed method determines an added value which represents how much the area is reduced. Experiments are performed to calculate an approximate added value without applying the proposed method because of the costly calculation requirements. The results of the experiments and the obtained added values are also reported as final evaluation of the study.

There are many methods that can be used to compute the geographic similarity between regions represented through areas in a two dimensional space. However, it is the rough set based membership function that allows an estimate of the similarity between a subzone formed by the data. The major objective behind this paper is to measure the similarity of GIS subzones on a discrete dataset. This has a varied number of applications not only in GIS and epidemiology but also in clusters analysis and artificial intelligence.

Conventional identification algorithms of space- frequency block codes (SFBC) only utilize the space- domain redundancy between any two receive antennas. In this paper, a novel two-dimensional space-frequency domain redundancy based SFBC identification algorithm for frequency selective fading is proposed in which the detection probability varies with the number of subcarriers. In particular, space-domain redundancy is utilized to construct the cross-correlation function of the estimator while frequency-domain redundancy is incorporated in the hypothesis test statistic. Simulation results verify the viability of the proposed algorithm and its superior performance for short observation periods with comparable computational complexity to the conventional algorithms.

The present work offers the solution for a target speed estimation in two dimensional space by the distributed radar systems. The proposed method supposes initial separated estimation of speeds in all channels (as it is done in conventional systems) and further refined estimation of the target speed by the joined least squares optimization. It was shown that the refined estimation allows obtaining of more precise speed estimate.

In this paper, we propose a closed-form solution for time-difference-of-arrival (TDOA) based joint source and sensor localization in two-dimensional space (2D). This closed-form solution is a combination of two closed-form solutions for time-of-arrival information recovery and time-of-arrival (TOA)-based joint source and sensor localization in 2D. In our previous works, we derived closed-form solutions for TOA-based joint source and sensor localization and near-closed-form solutions for TOA information recovery in three-dimensional space (3D). Since the localization in 2D is simpler than that in 3D, closed-form solutions for both problems in 2D are derived in this paper. The root-mean-square errors (RMSEs) achieved by the proposed closed-form solution are compared with the Cramer-Rao lower bound (CRLB) in synthetic experiments. The results show that the proposed solution works well in both low-noise and noisy cases and with both small and large numbers of sources and sensors.

In this paper, permutation invariant and collision free trajectories for a formation control problem are generated by using the root locus principle. A polynomial based representation space of multiple robots in two dimensional space is proposed, and the invariant properties in this space are analyzed. The formation control problem is solved in the representation space. A set of permutation invariant trajectories is generated by the generalized root locus dynamics. This method can be realized without the knowledge of global coordinates, but only with the local interaction between robots. In addition, the generalized root locus principle gives one degree of freedom to choose a different assignment in the formation. At the end, an example of permutation invariant safe control is provided.

In this paper, a new algorithm for visualization of high-multidimensional data is described. The algorithm follows several steps. At first, centers representing several categories are selected, and Euclidean distances between these centers are calculated in a high-dimensional space. Then these centers are placed in a 2-dimensional space in such a way that distances in this 2-dimensional space are similar to distances in the high-dimensional space. Next individual patterns are placed one-by-one in the 2-dimensional space trying to keep the similar distances in a high-dimensional and 2-dimensional space. With this algorithm, it was possible to visualize many high-dimensional data sets. The algorithm was successfully verified in several real life problems. It turned out that in some cases, which were until now considered as not linearly separable, became easily separable once patterns were transformed in the 2-dimensional space using the proposed algorithm.

By the cooperative and competitive PSO algorithm, the goal of this study is to provide the cooperative trajectories of multiple UAVs in the three dimensional space. To effectively reduce the dimension of this problem, the optimization process is mainly divided into two substages to reduce the difficulty of selecting the weights of objectives and constraints in the considered objective function. Considering several objectives and constraints, the cooperative trajectories in the first substage are given by the cooperative and competitive PSO algorithm in the two dimensional space. In the second substage, the altitude of cooperative trajectories is adjusted according to the considered objectives and constraints. In the complicated scenarios, simulation results demonstrate the effectiveness and the robustness of the cooperative and competitive PSO algorithm, which possibly provides one guideline for optimal cooperative planning trajectories of multiple UAVs in the three-dimensional space.

Robotic manipulators are the most important components in the present manufacturing industry for handling materials and manipulation. It is important to note that these manipulators are used in the complex planar and spatial work spaces to perform the task. Further, it is also very difficult to manipulate and dynamically control the manipulators when the degrees of freedom (DOF) of the manipulator are increased. In the present manuscript, the dynamic analysis and design of PID controller for two different manipulator configurations, namely planar and spatial manipulators have been attempted. Moreover, both the manipulators considered in this study are provided with 4-DOF and dynamic analysis has been carried out using Lagrange-Euler (L-E) formulation. The main difference between the planar and spatial manipulator is that the former works in the two dimensional space and later works in a three dimensional space. In addition to the dynamic analysis, PID controllers have also been designed for the said configurations to follow a path between the given boundary conditions. Further, the developed controllers are tested in simulations, and found working satisfactorily.

In this paper, we propose a Genetic Algorithm (GA) for solving the problem of dimensional ordering in Radial Visualization (Radviz) systems. The Radviz is a non-linear projection of high-dimensional data set onto two dimensional space. The order of dimension anchors in the Radviz system is crucial for the visualization quality. We conducted experiments on five common data sets and compare the quality of solutions found by GA and those found by the other well-known methods. The experimental results show that the solutions found by GA for these tested data sets are very competitive having better cost values than almost all solutions found by other methods. This suggests that GA could be a good approach to solve the problem of dimensional ordering in Radviz.

In this paper the two-dimensional space-time clutter is simulated for arbitrary postures of aircraft. First the detection area is divided into many scattering cells, and for each scattering cell the return signal is calculated according to the radar equation, then the received signal of radar for sidelooking arrays or forward looking arrays is presented. Finally the simulation experiment is performed and the results shows the effectiveness of our method.

Mediterranean Control Association 2011 19th Mediterranean Conference on Control and Automation, MED 2011 -- 20 June 2011 through 23 June 2011 -- Corfu -- 86335 The paper examines cyclic persistent networks at the level of sensing and control architectures that are needed to maintain the shape of a multi-agent formation in two dimensional space, while the formation moves as a cohesive whole. The key tools we use are rigidity theory and graph theory. Then, the paper focuses on the planner level and controller level of the architecture by designing fuzzy logic based planner and fuzzy controller of individual agents. We simulate the fuzzy planner and the fuzzy controller on kinematic unicycles for an exemplary cyclic formation generated by the results obtained in the first half of the paper. The validity of the proposed approach in the shape control of multi-agent formations is verified through simulation experiments. © 2011 IEEE.

When the time resolution of the signals is not so good, we can't rely on the time of arrival (TOA) information. On the other hand, if the frequency resolution of the signals is good, than frequency of arrival (FOA) informations will be more reliable. Localization of a moving, non-maneuvering target is possible by using Doppler-shift measurements in MIMO radar systems. A new method for target localization in frequency-only MIMO radar is proposed and it is compared with previous method. These methods use only received frequencies, and all of other unknown quantities can be written by using locations of the target, the receivers and the transmitters. If the received frequencies are known only, desired area can be searched grid by grid for all possible (x, y) coordinates to find the position of the target in 2D space.

In this paper, an image-based approach for the generation of offset curves from point cloud is presented. The offset curves/surfaces can be applied to refine the prototype produced by using the rapid prototype method to remedy the potential low precise problem. To reduce the computational complexion, in the approach, the cloud data is segmented into a number of layers by slicing the point cloud along a user-specified direction, i.e. machining direction. The data points in each layer are projected onto a plane that is perpendicular to the machining direction. Furthermore, the data points on the place are transformed into grey-level values on a two dimensional space based on the distance away from the plane. After that, the offset curves can be directly computed by using the linear diffusion-based segmentation method. Although a perfect result hasn't be achieved, the numerical experimental result shows that the proposed approach is more prospective than the existing ones. One of most advantages is more efficiency and with much less computational cost.

The computation of the Euclidean distance is an important aspect in many signal processing applications, especially those related to pattern classification systems and communication systems. Most communication systems compute the Euclidean distance between a given set of candidates (called objects) and a given vector (called a query). In this paper we present an algorithm for the computation of the Euclidean distance in a two dimensional space, which is suitable for VLSI implementation. The algorithm only computes the necessary distances, in contrast to current approaches, which rely on the availability of the distances of all candidates to the center. The advantages of the proposed algorithm over conventional ones are presented.

This methodology is to realize high real-time and high accuracy effect on complex system fault analysis. This methodology selects abnormal information as input space. As to input space, fault cells can be reached through fuzzy decomposition in two-dimensional space. As to output space, this paper introduces respectively two different methods. One method is the same as fuzzy decomposition of input space. The other is depended on fault type characteristics to partition artificially and experientially output space. Designing reasonably logic mapping deduction models, this paper presents fault cells-cells mapping and fault cells-space mapping analysis models. Taking transformer fault diagnosis as experimental example, it proves this methodology can be well in decreasing dramatically many useless interferential input variables, mining and explaining key characteristics and inner relation of abnormal information. The experimental result is also validated to be satisfied to solve the contradiction between high real-time and high accuracy.

We present an algorithm for sensor placement with redundancy where each point in a 2-dimensional space is covered by at least k sensors under the constraint that all the sensors are located away from each other. We reduce the problem to distributing points evenly on the surface of a torus manifold and solve it computationally by minimizing the Riesz energy. We also study the case where the coverings are incrementally constructed. We illustrate our approach with numerical results and compare it to similar approaches in dispersed dither mask halftoning.

Study of spatial relations between biological objects is crucial for understanding biological processes. Monitoring drug or particle delivery inside cells and studying the dynamics of subcellular proteins are some of the examples. Biological applications have varying demands in terms of speed and accuracy. While accuracy may be the most important factor for small-scale biology, speed is also a concern for high-content/high-throughput screening applications. In this paper we present a variety of algorithms for inter-object spatial relations in two-and three-dimensional space. These algorithms provide trade-off between speed and accuracy, depending on the requirements of the application. Results for speed and accuracy are reported for real as well as synthetic data sets.

Inspired by natural swarming and flocking behaviors, in this paper we study a series of problems concerning motion control for autonomous multiagent formations moving in a two dimensional space and avoiding collision with each other as well as obstacles. We give a hierarchical task map and argue that if the formation is kept rigid via implementation of certain distance maintenance constraints, then no inter-agent collision can happen. We outline recently developed procedures based on graph theory for achieving this. We then take the study further by investigating and discussing two strategies for obstacle avoidance by the entire formation. We present some simulation results for the motion of an asymmetrically controlled formation with no global leader, in presence of multiple obstacles on the plane of interest.

A space vector PWM (SVPWM) technique for multi-phase voltage source inverters (VSI), based on a multi-dimensional space approach, is presented. The additional degrees of freedom, which appear as the number of phases increases, make the SVPWM more complex because VSI space vectors are not in a single two-dimensional space (as in three-phase case) any more. Existing approaches are based on n-dimensional space decomposition into (n-1)/2 two-dimensional sub-spaces. The methodology proposed here is different since the voltage space vectors are selected on the basis of criteria that are formulated for the multi-dimensional space, so that all the two-dimensional sub-spaces are simultaneously considered. The paper details the mathematical analysis that establishes the necessary conditions for appropriate selection of the voltage space vectors in the multi-dimensional case. Different criteria for the general n-phase case are presented for the selection of the VSI space vectors and the methodology is verified by simulation of a five-phase VSI.

In this paper, we investigate different variants of the recently proposed cost-reference particle filters (CRPFs) and study their application to the problem of tracking of a high-speed maneuvering target in the two-dimensional space. CRPFs drop all probabilistic assumptions required by conventional particle filters and, as a consequence, lead to practically more robust algorithms. We introduce some suitable and natural modifications of CRPFs in order to increase their efficiency and reduce their computational complexity. Computer simulations are provided to illustrate the performance of the new alternatives.

In this paper, the overlap algorithm is applied to the nonstandard finite-difference time-domain (NS-FDTD) method using a nonuniform mesh in a 2-D space. The characteristics of the overlap algorithm are numerically examined and compared with a no overlap algorithm. The results show that the reflection rate from the interface of the two meshes using the overlap algorithm is less than -80 dB, which is smaller than that of the NS-FDTD method without the overlap. Consequently, it is shown that the overlap algorithm is more suitable for the NS-FDTD method when using a nonuniform mesh. The overlap algorithm is successfully applied to the analysis of a dielectric flat panel and a corrugated surface., application/pdf

The biological activity of RNA depends on the way it folds into secondary structures. Presented here is a framework for exploratory motif searching in the space of RNA secondary structures. A collection of RNA sequences, suspected of having a particular biological activity, is fragmented into overlapping pieces of a uniform size. Each piece is folded and the details of the fold are used to annotate the primary structure. Distances between annotated structures are computed. The distance matrix for the structures is then projected into the Euclidean plane for visualization and detection of clusters. A motif is taken to be a cluster in the two dimensional space. An instance of the framework is implemented for testing on a data set containing examples of the Iron Response Element in the following manner. Folding is performed with the Mfold package. A depth-of-fold that records stems and loops onto the primary sequence is used to annotate the pieces of RNA. Dynamic programming is used to find distances between pieces of annotated primary sequence. An evolutionary algorithm is then used to find a one-to-one mapping of pieces of RNA to points in the plane that has acceptable distortion of the distances found with dynamic programming. This one-to-one mapping is a form of non-linear projection that optimizes for fidelity of projected distances to the distances derived from the Iron Response Element data set.

Non-destructive space charge measurement techniques have been used to investigate space charge behavior in insulating materials. Direct multi-dimensional space charge measurement systems are also required to observe for the localized space charge distribution in applications of the insulating material. Some multi-dimensional space charge measurement systems have been developed in the pulsed electro-acoustic (PEA) and pressure wave propagation (PWP) method, however, it is difficult to measure space charge distribution in real time in these systems. Since the space charge behaviour is generally in transient, the high repetition two-dimensional (2D) space charge measurement system in the lateral and thickness direction for transient space charge has been developed using multiple acoustic sensors in the PEA method. This paper described performances of the high repetition rate 2D space charge measurement system.

We propose some techniques to improve the exploration method based on BVP and demonstrate that, at least, for exploration in two dimensional space, we can reduce enormously the computation cost of the harmonic function method for exploration without losing the important properties of the method. Switching between local and global potential calculation and using an adaptive activation window result in a computationally efficient and refined mapping process.

In this paper, we state the basic governing relationships between a constellation's motion in physical two dimensional space and imaging objectives. We then introduce a class of motions that satisfies imaging objectives and seek simple solutions to the problem of motion design and control of a formation for imaging applications. Results indicate a tradeoff between image quality and fuel expenditure for the proposed class of maneuvers.

Since the proportional navigation guidance law was first introduced, many of the researchers had proposed different methodologies to investigate the corresponding performances of all the existing guidance laws. In 1997, Yang and Yang introduced an unified approach, in that paper the authors found that under the proposed framework, all the existing guidance laws, namely IPN, TPN and PPN, are indeed special cases of the mentioned general guidance law. However, their results were restricted to two dimensional space. In this paper, the author not only extends the results to three dimensional space, but also to GIPN, GTPN and PPN. Unlike conventional researchers, a modified polar coordinate (MPC) is adopted. It is shown that with the property of this modified polar coordinate, for the line of sight based guidance laws (GIPN and GTPN) the number of differential equations required to fully describe the relative dynamics can be reduced from six to three, however, for the missile's velocity based guidance law, i.e. PPN, five differential equations are required. In the mean time all the terms of differential equations involve only products and additions of variables. For all the mentioned guidance laws in this paper, only two transformed variables are required to describe the capture region, while the third variable is required to provide the condition of finite turn rate. For each type of guidance laws (GIPN, GTPN and PPN), the corresponding time-to-go's are also derived.

We describe a solution to the problem of determining the kinematic feasibility of a dextrous hand to grasp a given object at a desired configuration in the two dimensional space. We refer to this problem as kinematic graspability. The kinematic configuration of a grasp is defined in terms of a set of contact pairs between the topological features of the hand and the object. We derive the sufficient conditions in order for the hand to make the desired contact and avoid collision. These conditions are then formulated as a constrained nonlinear global optimization problem, whose solution yields a definitive answer to kinematic graspability for a grasp configuration. Numerical examples are provided to illustrate the method.

We establish that an arbitrary narrowband multi path field in any circular region in two dimensional space has an intrinsic functional dimensionality of (πe) R/λ ≈ 8.54 R/λ. that scales only linearly with radius R/λ. in wavelengths. This result implies there is no such thing as an arbitrarily complicated multi path field. That is, a field generated by any number of nearfield and farfield, specular and diffuse multipath reflections is no more complicated than a field generated by a limited number plane waves. As such, there are limits on how rich multipath can be. This result has significant implications including means: i) to determine a parsimonious parameterization for arbitrary multipath fields, ii) of synthesizing arbitrary multi path fields with arbitrarily located nearfield or farfield, spatially discrete or continuous sources. We give examples of multipath field analysis and synthesis.

Since the proportional navigation guidance law was first introduced, many of the researchers had proposed different methodologies to investigate the corresponding performances of all the existing guidance laws. In 1997, Yang and Yang introduced an unified approach, in that paper the authors found that under the proposed framework, all the existing guidance laws, namely TPN, IPN and PPN, are indeed special cases of the mentioned general guidance law. But their results were restricted to two dimensional space. In this paper, the author not only extends the results to three dimensional space, but also to GTPN, GIPN and PPN. Unlike conventional researchers, a modified polar coordinate (MPC) is adopted. It is shown that with the property of this modified polar coordinate, the number of differential equations required to describe the relative dynamics can be reduced from six to three, and all the terms of differential equations involve only products and additions of variables. For all the mentioned guidance laws in this paper, to describe the capture area we need only two transformed variables, while the third variable is required to provide the condition of finite turn rate.