bluuebunny/crossref_metadata_2025_split huggingface dataset:
Asymptotic output tracking of a class of nonlinear systems by means of an observer
Authors: Martínez‐Guerra Rafael , Suarez Rodolfo , León‐Morales Jesús De 
Published: August 2002

AbstractAn observer‐based controller strategy for the asymptotic output tracking of a class of nonlinear systems is proposed. The generalized observability canonical form (𝒢𝒪𝒞ℱ) introduced by Fliess, is the main ingredient in our approach. Our tracking controller actually achieves uniform asymptotic stability by linearizing the tracking error. Two examples are considered to illustrate the effectiveness of the suggested approach. Copyright © 2001 John Wiley & Sons, Ltd.
Stabilization of invariant tori in Hamiltonian systems under persistently acting disturbances
Authors: Polushin Ilya G. 
Published: August 2002

AbstractThe problem of invariant tori stabilization in multi‐degrees‐of‐freedom Hamiltonian systems under uniformly bounded disturbances is considered. The main result gives the conditions for ultimate boundedness of trajectories of controlled system under disturbances with respect to the torus to be stabilized. The estimates for region of attraction and ultimate bound are obtained. The essential role in the proof is played by Lemma 1, which gives the conditions for ultimate boundedness with respect to a given nonnegative smooth functionVwithout assumption of negative (semi)‐definiteness of time derivative ofV. Copyright © 2001 John Wiley & Sons, Ltd.
DC‐to‐AC power conversion on a ‘boost’ converter
Authors: Sira‐Ramírez Hebertt 
Published: August 2002

AbstractIn this article, we provide an approximate sliding mode control‐based solution to the DC–AC power conversion problem on a ‘boost’ converter. The approach uses the flatness property of the system as a pivot for generating a sequence of minimum phase output reference trajectory candidates. The generated candidates are obtained as differential parameterizations of the minimum phase inductor current variable in terms of the non‐minimum phase desired output capacitor voltage. The associated residual dynamics of the ideal sliding motions is shown to reasonably approximate the desired biased sinusoidal output capacitor voltage signal. Copyright © 2001 John Wiley & Sons, Ltd.
Set membership localization and mapping for autonomous navigation
Authors: Di Marco M. , Garulli A. , Lacroix S. , Vicino A. 
Published: August 2002

AbstractIn this paper a set theoretic estimation approach is proposed for dynamic localization problems in the area of mobile robot autonomous navigation. Self‐localization of mobile robots is one of the most important problems in long range autonomous navigation. When moving in an unknown environment, the navigator must exploit measurements from exteroceptive sensors to build a map, identify landmarks and, at the same time, localize itself with respect to them. This problem is known as simultaneous localization and mapping (SLAM).Under the hypothesis that the errors affecting all sensor measurements are unknown but bounded, set membership techniques, successfully employed in the robust identification area of research, are exploited to devise procedures for guaranteed estimation of robot and landmarks positions in terms of uncertainty regions. Set approximation is adopted in order to provide efficient recursive algorithms, suitable for on‐line implementation. Copyright © 2001 John Wiley & Sons, Ltd.
Idle speed control of a direct injection spark ignition stratified charge engine
Authors: Grizzle J. W. , Buckland Julia , Sun Jing 
Published: August 2002

AbstractIdle speed control is investigated for a direct injection, spark ignition, stratified charge (DISC) engine equipped with an electronic throttle. Such engines can be operated in multiple combustion modes. When operating in stratified charge combustion mode, they are very different from conventional stoichiometric engines, creating new opportunities for improved speed control. With current after‐treatment technology, simultaneous high fuel economy and emissions conversion efficiency cannot be achieved by operating the engine in a steady‐state manner: it must be cycled between running ultra‐lean (for fuel economy) and rich (to service the after‐treatment system). An idle speed control system is designed to meet the considerable feedback control demands required by these new engines. Copyright © 2001 John Wiley & Sons, Ltd.
Design of full state feedback finite‐precision controllers
Authors: D'Andrea Raffaello , Istepanian Robert S. H. 
Published: August 2002

AbstractIn this paper, the Generalized L2 Synthesis framework is brought to bear on the problem of control design of full state feedback finite‐precision controllers. In particular, we investigate the problem of designing full state feedback controllers that achieve guaranteed H‐infinity performance objectives, subject to finite precision constraints on the controller. It is shown that by adopting the Generalized L2 Synthesis framework, the errors in the controller implementation can be captured as full structured uncertainty, and computationally tractable linear matrix inequality techniques used for analysis and synthesis. Copyright © 2002 John Wiley & Sons, Ltd.
The kinematics for redundantly actuated omnidirectional mobile robots
Authors: Yi Byung‐Ju , Kim Whee Kuk 
Published: August 2002

AbstractOmnidirectional mobile robots have been popularly employed in several application areas. However, the kinematics and singularity analysis for these systems have not been clearly identified, especially for the redundantly actuated case, which is common in current omnidirectional mobile robots. In light of this fact, this article introduces two different kinematic approaches for a typical omnidirectional mobile robot having three caster wheels, and examines singularity configurations of such systems. Then, a singularity‐free load‐distribution scheme for a redundantly actuated three‐wheeled omnidirectional mobile robot is proposed. Through simulation, several advantages of the redundantly actuated mobile robot (singularity avoidance, input‐load saving, and exploiting several subtasks) are presented. © 2002 Wiley Periodicals, Inc.
Minimal realizations of spatial stiffnesses with parallel or serial mechanisms having concurrent axes
Authors: Huang Shuguang , Schimmels Joseph M. 
Published: August 2002

AbstractThis article presents a new method for the synthesis of an arbitrary spatial elastic behavior with an elastic mechanism. The mechanisms considered are parallel and serial mechanisms with concurrent axes. We show that any full‐rank spatial stiffness matrix can be realized using a parallel mechanism with all spring axes intersecting at a unique point. It is shown that this intersection point must be the center of stiffness. We also show that any full‐rank spatial compliance matrix can be realized using a serial mechanism with all joint axes intersecting at a unique point. This point is shown to be the center of compliance. Synthesis procedures for mechanisms with these properties are provided. The realizations are shown to be minimal in the sense that both the number of screw components and the total number of components are minimum. © 2001 John Wiley & Sons, Inc.
The dexterity and singularities of an underactuated robot
Authors: Roberts Rodney G. 
Published: August 2002

AbstractUnderactuated robots are robotic systems with more joints than actuators. A robot may be underactuated by design as in the case of a hyper‐redundant robot with passive joints or may become underactuated as a result of an actuator failure. In this article, we examine the dexterity of underactuated robots whose passive joints operate in either a locked or free‐swinging mode. The ability to an analyze the dexterity of an underactuated robot has important applications especially for the control of passive joints with brakes and for the fault tolerance analysis of an otherwise fully actuated kinematically redundant robot. The approach applied here is to use kinematics and dynamics‐based formulations of manipulator dexterity. We then characterize passive‐joint singularities, i.e., configurations where full end‐effector control is lost because one or more joints are passive instead of active. Lastly, we introduce a new characterization of joint‐limit singularities, which are configurations where full end‐effector control cannot be achieved because one or more joints are at their joint limits. © 2001 John Wiley & Sons, Inc.
Manipulating deformable linear objects: Attachable adjustment‐motions for vibration reduction
Authors: Yue Shigang , Henrich Dominik 
Published: August 2002

AbstractThis paper addresses the problem of handling deformable linear objects in a suitable way to avoid acute vibration. Different types of adjustment‐motions that eliminate vibration of deformable objects and that can be attached to the end of an arbitrary end‐effector's trajectory are presented. For describing the dynamics of deformable linear objects, the finite element method is used to derive the dynamic differential equations. A genetic algorithm is used to find the optimal adjustment motion for each simulation example. Experiments are conducted to verify the presented manipulating method. © 2001 John Wiley & Sons, Inc.
Using OXSIMfor path planning
Authors: Cameron Stephen , Pitt‐Francis Joe 
Published: August 2002

AbstractWe address the issue of building scalable and reusable path planners for realistic robot manipulators working in three‐dimensional space amid complex geometry, by presenting the latest version of our robot manipulator planning toolbox, OxSIM. OxSIMis designed to greatly simplify the building of planners by providing core competence in three‐dimensional geometry. This is done by the provision of efficient routines for computing the distance between parts of the robot and its environment. A new version of OXSIM, written in C++, provides an object‐oriented interface to the basic system, which increases its ease of use. Here we give an overview of OxSIMand how it works and describe a modified version of the probabilistic road map planner that we have implemented under the framework. © 2001 John Wiley & Sons, Inc.
MPK: An open extensible motion planning kernel
Authors: Gipson Ian , Gupta Kamal , Greenspan Michael 
Published: August 2002

AbstractThe motion planning kernel (MPK) is a software system designed to facilitate development, testing, and comparison of robotic and geometric reasoning algorithms. Examples of such algorithms include automatic path planning, grasping, etc. The system has been designed to be open and extensible, so that new methods can be easily added and compared on the same platform. © 2001 John Wiley & Sons, Inc.
An evolutionary and local search algorithm for motion planning of two manipulators
Authors: Ridao M. A. , Camacho E. F. , Riquelme J. , Toro M. 
Published: August 2002

AbstractA method for obtaining coordinated motion plans of robot manipulators is presented. A decoupled planning approach has been used; that is, the problem has been decomposed into two subproblems: path planning, where a collision‐free path is found for each robot independently only considering fixed obstacles, and trajectory planning, where the paths are timed and synchronized to avoid collisions with other robots. This article focuses on the second problem. The proposed plan can easily be implemented by programs written in most industrial robot programming languages. The generated programs minimize the total motion time of the robots along their paths. The method does not require accurate dynamic models of the robots and uses an evolutionary algorithm followed by a local search which produces near optimal solutions with a relatively small computational cost. © 2001 John Wiley & Sons, Inc.
A novel adaptive bilateral control scheme using similar closed‐loop dynamic characteristics of master/slave manipulators
Authors: Ryu Jee‐Hwan , Kwon Dong‐Soo 
Published: August 2002

AbstractThis article presents a novel adaptive bilateral control scheme for obtaining ideal responses for teleoperation systems with uncertainties. A condition that is equivalent to getting an ideal response in teleoperation has been found to be making the closed‐loop dynamics of master and slave manipulators a similar form. An adaptive approach is applied to achieve similarity for the uncertain master and slave manipulators. Using the similar closed‐loop dynamic characteristics of master/slave teleoperation systems, excellent position and force tracking performance has been obtained without estimating the impedance of human and environment. The validity of the theoretical results is verified by experiments. © 2001 John Wiley & Sons, Inc.
When does a robot perceive a dynamic object?
Authors: Krishna K. Madhava , Kalra Prem K. 
Published: August 2002

AbstractRobots operating in a real‐time environment encounter both stationary and moving objects that need to be
negotiated using different schemes in general. Motion planning in a dynamic environment entails tracking moving
objects and predicting their future positions. However, this requires as a first step the classification of the
objects present in the environment as static or dynamic objects, a step that somehow seems to have been overlooked
in the literature dealing with navigation in dynamic environments. Presented here are four schemes for perceiving
the presence of dynamic objects in the robot's neighborhood. The first approach incorporates a network
architecture that classifies the robot's experience of the environment in terms of spatio‐temporal
sensor patterns as an experience of a static or dynamic object. The second method detects motion by observing
changes in the map of the environment it builds and updates. The remaining two approaches use a strategy for
representing the objects in the environment through clusters; inspecting the characteristics of the clusters
reveals the dynamic objects. These methods are denoted as STA (spatio‐temporal approach), MBA
(model‐based approach), and CBAI and CBAII (cluster‐based approach I and II),
respectively. The methods have been tested in environments that contain multiple dynamic objects amidst static
ones and their efficacy established. A brief comparison of these approaches in terms of criteria critical for
real‐time collision avoidance has also been presented. © 2002 John Wiley & Sons, Inc.
Real‐time actual pose determination of the general fully parallel spherical wrist, using only one extra sensor
Authors: Parenti‐Castelli Vincenzo , Di Gregorio Raffaele 
Published: August 2002

AbstractThe direct position analysis of the fully parallel spherical wrist with general geometry can have up to eight poses for a given set of leg lengths. This paper presents a procedure that makes use of one extra rotary sensor, suitably located in the wrist (in addition to the three linear sensors embedded in the leg servosystems) to enable the actual pose of the spherical wrist to be uniquely defined and the wrist direct position analysis to be computed in real time. Closed‐form solution of the direct position analysis is obtained, which makes it possible to refine the measurement provided by the extra sensor and consequently to improve the robustness of the procedure. Examples are reported that show the efficiency of the procedure. © 2001 John Wiley & Sons, Inc.
A general solution for the position, velocity, and acceleration of hyperredundant planar manipulators
Authors: Asl Farshid Maghami , Ashrafiuon Hashem , Nataraj C. 
Published: August 2002

AbstractA new approach for the solution of the position, velocity, and acceleration of hyperredundant planar manipulators following any twice‐differentiable desired path is presented. The method is singularity free, and provides a robust solution even in the event of mechanical failure of some of the robot actuators. The approach is based on defining virtual layers, and dividing them into virtual/real three‐link or four‐link subrobots. It starts by solving the inverse kinematic problem for the subrobot located in the lowest virtual layer, which is then used to solve the inverse kinematic equations for the subrobots located in the upper virtual layers. An algorithm is developed that provides a singularity‐free solution up to the full extension through a configuration index. The configuration index can be interpreted as the average of the determinants of the Jacobians of the subrobots. The equations for the velocities and accelerations of the manipulator are solved by extending the same approach, and it is shown that the value of the configuration index is critical in maintaining joint velocity continuity. The inverse dynamic problem of the robot is also solved to obtain the torques required for the robot actuators to accomplish their tasks. Computer simulations of several hyperredundant manipulators using the proposed method are presented as numerical examples. © 2002 John Wiley & Sons, Inc.
The significance of flood regimes for carabid beetle and spider communities in riparian habitats—a comparison of three major rivers in Germany
Authors: Bonn Aletta , Hagen Katja , Reiche Dagmar Wohlgemuth‐von 
Published: August 2002

AbstractRiver regulation and water management practices have led to alteration of the flood regimes of all large rivers in Germany. To investigate its influence on the terrestrial arthropod fauna, a comparative study was carried out on the distribution of ground beetles (Carabidae) and spiders (Araneae) at the potamal sections of three large rivers in northern Germany, the Rivers Weser, Elbe and Oder. The three rivers differ markedly in their flood dynamics, mainly owing to weirs and polder management practices, but also owing to natural conditions in their headwaters. In total, 45 sites were examined with a total capture of 46 727 carabid beetles and 38 066 adult spiders, representing 178 and 209 species, respectively. Using multivariate TWINSPAN analyses we found that the ground beetle species assemblages clearly varied according to the different flood regimes. By contrast, the spiders differentiate well between sites of different habitat structure.In particular, the river margins hosted a specialized carabid fauna, and the alluvialQuercus–Ulmusforests were habitat for some rare and endangered carabid and spider species. Whereas the fauna of the strongly regulated River Weser was impoverished regarding stenotopic hygrophilous species, the fauna of the more natural Rivers Elbe and Oder depended very much on the duration and timing of the flooding, as well as on the local micro‐topographical situation. It is concluded that low lying areas behind dykes of the Elbe, or in polders of the Oder, which become frequently inundated by river or ground water, are extremely valuable for invertebrate conservation. The data suggest that careful polder management may support suitable habitat creation for riparian species, as long as the inundation scheme corresponds to natural flood dynamics conditions. Copyright © 2002 John Wiley & Sons, Ltd.
On probabilistic elimination of generalized quantifiers
Authors: Kaila Risto 
Published: August 2002

AbstractLet 𝒬 be a collection of generalized quantifiers. We give a convenient characterization for the cases where the logic ℒ︁(𝒬) has quantifier elimination for an arbitrary class of structures. The results provide a method to prove zero‐one and convergence laws for such logics with arbitrary sequences of probability measures of finite structures. © 2001 John Wiley & Sons, Inc. Random Struct. Alg., 19, 1–36, 2001
Physical–statistical methods for determining state transition probabilities in mobile‐satellite channel models
Authors: Saunders S. R. , Tzaras C. , Evans B. G. 
Published: August 2002

AbstractSignal propagation in land mobile satellite (LMS) communication systems has for the last decade become an essential consideration, especially when high‐rate data services are involved. As far as urban or suburban built‐up areas are concerned, the extent of the influence is mainly restricted to the roadside obstacles, since the satellite is positioned at relatively high elevation angles in most practical situations. Probably, the most common model currently used for representing the LMS channel is the Lutz model, which uses two states to represent line‐of‐sight and non‐line‐of‐sight conditions. Transitions between these states are described by transition probabilities which are a function of the environment and the satellite elevation angles. Similarly, an extension to the model allows a four‐state description to be used for the states associated with a pair of satellites used in a dual‐diversity configuration. Calculation of the transition probabilities then requires knowledge of the correlation between the two channels, which in turn depends on the spatial characteristics of the local environment around the mobile.In both cases, the transition probabilities have been derived basically from measurements in the past. In the new approaches described in this paper, physical–statistical principles are applied to construct analytical formulas for the probabilities of shadowing and the correlation between states. These expressions apply particularly to systems operated in built‐up environments, and have been checked against numerical experiments and against direct measurements. In both cases excellent agreement is obtained. Copyright © 2001 John Wiley & Sons, Ltd.
Joint spectrum and power optimization in the design of the UMTS satellite component
Authors: Cianca Ernestina , De Fina Silvia , Ruggieri Marina 
Published: August 2002

AbstractThe paper provides a power and spectrum joint analysis of the universal mobile telecommunications system (UMTS) satellite component, based on the wideband code division multiple access (W‐CDMA) air interface. In fact, power and spectral efficiency may become highly conflicting requirements in a satellite system and a trade‐off analysis is needed to drive a proper dimensioning of the satellite. The proposed approach allows a dimensioning of the satellite component either in terms of orbit and power budget or in terms of additional capacity for the terrestrial section, for specified orbit and power limitations. The impact of candidate frequency bands, orbit type and diversity on both spectral and power requirements of the satellite component is evaluated. For given traffic requirements, power‐vs‐spectrum trade‐off is proposed which ensures a proper resources utilization. The efficiency evaluation accounts for: beams overlapping, ortho gonality, voice activity factor, diversity and cross‐polarization frequency reuse. Perfect power control is assumed and the effect of the excess power required by the shadowed users is accounted for in the interference calculation. Furthermore, still in the frame of a proper resource exploitation, a possible optimization of capacity through the use of unpaired bands in the two link directions is analysed. Copyright © 2001 John Wiley & Sons, Ltd.
Reliable multicast via satellite: a comparison survey and taxonomy
Authors: Koyabe Martin W. , Fairhurst Godred 
Published: August 2002

AbstractIP multicasting is an important service, which will be provided by the next generation Internet. A range of applications has emerged which take the advantage of multicast delivery. However, several factors currently hinder large‐scale deployment of terrestrial multicast services. It is particularly difficult to support delivery to large groups of users.Satellites offer a natural way to extend the multicast service to reach this large number of users. They may offer high capacity (especially when using next generation satellite systems) and also eliminate the need for a large number of intermediate routing hops. There are important differences in the way multicast applications operate over satellite. This paper therefore reviews the key design paradigm and offers a critical comparison between different reliable multicast protocol techniques based on a taxonomy. The suitability of a set of the most common reliable multicast protocols is assessed within a satellite environment and conclusions are presented. Copyright © 2001 John Wiley & Sons, Ltd.