pinecone/core-2020-05-10-deduplication huggingface dataset:
Position tracking in delayed bilateral teleoperators without velocity measurements

This work considers the control of nonlinear bilateral teleoperators with variable time delays without the need of velocity measurements. The recently proposed Immersion and Invariance observer is used to obtain an exponentially convergent estimate of the unmeasured velocities. Under the classical assumption that the human operator and the environment define passive, velocity to force, maps, it is proved that with this observer and a Proportional plus damping controller, velocities and position error are globally bounded. Finally, in the case that the human operator and the environment do not exert forces on the local and remote manipulators, respectively, global asymptotic convergence of velocities and of position error to zero is achieved. The theoretical results are sustained with simulations using a couple of two degrees-of-freedom nonlinear manipulators.Postprint (author's final draft
An LMI approach to robust fault estimation for a class of nonlinear systems

The paper presents a robust fault estimation approach for a class of nonlinear discrete-time systems. In particular, two sources of uncertainty are present in the considered class of systems, that is, an unknown input and an exogenous external disturbance. Thus, apart from simultaneous state and fault estimation, the objective is to decouple the effect of an unknown input while minimizing the influence of the exogenous external disturbance within the inline image framework. The resulting design procedure guarantees that a prescribed disturbance attenuation level is achieved with respect to the state and fault estimation error while assuring the convergence of the observer. The core advantage of the proposed approach is its simplicity by reducing the fault estimation problem to matrix inequalities formulation. In addition, the design conditions ensure the convergence of the observer with guaranteed inline image performance. The effectiveness of the proposed approach is demonstrated by its application to a twin rotor multiple-input multiple-output systemPostprint (author's final draft
Continuous output feedback stabilization for nonlinear systems based on sampled and delayed output measurements

This paper addresses the problem of output feedback stabilization for nonlinear systems with sampled
and delayed output measurements. Firstly, sufficient conditions are proposed to ensure that a class of
hybrid systems are globally exponentially stable. Then, based on the sufficient conditions and a dedicated
construction continuous observer, an output feedback control law is presented to globally exponentially
stabilize the nonlinear systems. The output feedback stabilizer is continuous and hybrid, and can be derived
without discretization. The maximum allowable sampling period and the maximum delay are also given.
At last, a numerical example is provided to illustrate the design methods.The National Science Foundation of China (61174216, 61374028, 51177088,
 61273183]), the Grant National Science Foundation of Hubei Provincial (2013CFA050), the Scientific
 Innovation Team Project of Hubei Provincial Department of Education (T201504).http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-12392017-09-30hb2016Electrical, Electronic and Computer Engineerin
Robust $H_\infty$ Estimation of Uncertain Linear Quantum Systems

We consider classical estimators for a class of physically realizable linear
quantum systems. Optimal estimation using a complex Kalman filter for this
problem has been previously explored. Here, we study robust $H_\infty$
estimation for uncertain linear quantum systems. The estimation problem is
solved by converting it to a suitably scaled $H_\infty$ control problem. The
solution is obtained in the form of two algebraic Riccati equations. Relevant
examples involving dynamic squeezers are presented to illustrate the efficacy
of our method.Comment: Minor corrections, 14 pages, 3 figures, International Journal of
  Robust and Nonlinear Contro
Stabilization by Unbounded-Variation Noises

In this paper, we claim the availability of deterministic noises for
stabilization of the origins of dynamical systems, provided that the noises
have unbounded variations. To achieve the result, we first consider the system
representations based on rough path analysis; then, we provide the notion of
asymptotic stability in roughness to analyze the stability for the systems. In
the procedure, we also confirm that the system representations include
stochastic differential equations; we also found that asymptotic stability in
roughness is the same property as uniform almost sure asymptotic stability
provided by Bardi and Cesaroni. After the discussion, we confirm that there is
a case that deterministic noises are capable of making the origin become
asymptotically stable in roughness while stochastic noises do not achieve the
same stabilization results.Comment: 22 pages, 5 figure
An alternative approach to anti-windup in anticipation of actuator saturation

12 month embargoTraditionally, an anti-windup compensator is activated when control signal saturation occurs. An alternative approach is to activate the compensator at a level below that of the physical control constraints: the anti-windup compensator is activated in anticipation of actuator saturation. Recent studies have proposed systematic methods for the construction of such anticipatory anti-windup compensators, but a pseudo-LPV representation of the saturated system has been central to these results. This paper approaches the anticipatory anti-windup problem for open-loop stable plants using a 'non-square' sector condition, which is associated with a combination of deadzone nonlinearities. The advantage of this approach is that it leads to synthesis routines, which bear a close resemblance to those associated with traditional immediately activated anti-windup compensators. A by-product of this approach also appears to be that the arising compensators are better numerically conditioned. Some simulation examples illustrating the effectiveness of anticipatory anti-windup compensators and some comments on their wider use complete the paper.Peer-reviewedPost-prin
Cluster Synchronization of Coupled Systems with Nonidentical Linear
  Dynamics

This paper considers the cluster synchronization problem of generic linear
dynamical systems whose system models are distinct in different clusters. These
nonidentical linear models render control design and coupling conditions highly
correlated if static couplings are used for all individual systems. In this
paper, a dynamic coupling structure, which incorporates a global weighting
factor and a vanishing auxiliary control variable, is proposed for each agent
and is shown to be a feasible solution. Lower bounds on the global and local
weighting factors are derived under the condition that every interaction
subgraph associated with each cluster admits a directed spanning tree. The
spanning tree requirement is further shown to be a necessary condition when the
clusters connect acyclicly with each other. Simulations for two applications,
cluster heading alignment of nonidentical ships and cluster phase
synchronization of nonidentical harmonic oscillators, illustrate essential
parts of the derived theoretical results.Comment: 22 pages, 4 figure
Fault Detection and Identification - a Filter Investigation

This paper develops a new active fault tolerant control system based on the
concept of analytical redundancy. The novel design consists of an observation
filter based fault detection and identification system integrated with a
nonlinear model predictive controller. A number of observation filters were
designed, integrated with the nonlinear controller and tested before reaching
the final design which comprises an unscented Kalman filter for fault detection
and identification together with a nonlinear model predictive controller to
form an active fault tolerant control system design
Robust fault estimation based on zonotopic Kalman filter for discrete-time descriptor systems

This paper proposes a set-based approach for robust fault estimation of discrete-time descriptor systems. The considered descriptor systems are subject to unknown-but-bounded uncertainties (state disturbances and measurement noise) in predefined zonotopes and additive actuator faults. The zonotopic fault estimation filter for descriptor systems is built based on fault detectability indices and matrix to estimate fault magnitude in a deterministic set. The zonotopic fault estimation filter gain is designed in a parameterized form. Within a set-based framework, following the zonotopic Kalman filter, the optimal filter gain is computed by minimizing the size of the corresponding zonotopes to achieve robustness against uncertainties and the identification of occurred actuator faults. Besides, boundedness of the proposed zonotopic fault estimation is analyzed, which proves that the size of obtained fault estimation bounds is not growing in time. Finally, the simulation results with two application examples are provided to show the effectiveness of the proposed approach.Peer ReviewedPostprint (author's final draft
On the design of gain-scheduled trajectory tracking controllers

International Journal  of Robust and Nonlinear Control, special issue on Gain-Scheduling,  2002, 12:797-839.The article of record as published may be found at http://dx.doi.org/10.1002/rnc.705A new methodology is proposed for the design of trajectory tracking controllers for autonomous vehicles. The design technique builds on gain scheduling control theory. An application is made to the design of a trajectory tracking controller for a prototype autonomous underwater vehicle (AUV). The effectiveness and advantages of the new control laws derived are illustrated in simulation using a full set of non-linear equations of motion of the vehicle. Copyright # 2002 John Wiley & Sons, Ltd
Dissipative systems: from physics to robust nonlinear control

23 páginas, 6 figurasIn this paper, we explore connections between the underlying physics of dissipative systems and nonlinear\ud
robust control. In particular, we concentrate on the problem of stabilizing stationary solutions of nonlinear\ud
dissipative systems with states distributed in space. Dissipative systems are equipped with an entropy\ud
function which we employ to relate dissipation with the Hamilton–Jacobi–Bellman equation. This relation\ud
allows us to establish formal links between the dynamic properties of dissipative systems, passivity and\ud
optimal stabilizing control, as it is understood in systems theory. Robustness issues in controller design,\ud
are also discussed in the context of front or pulse spatial pattern stabilization.The authors acknowledge generous support from Plan Nacional de Investigaci !on Cient!iifica (MCyTSpain),\ud
Project PPQ2001-3643.Peer reviewe
Relationship Between Nighttime Vital Sign Assessments and Acute Care Transfers in the Rehabilitation Inpatient

Purpose  To investigate the role of nighttime vital sign assessment in predicting acute care transfers ( ACT ) from inpatient rehabilitation.    Design  Retrospective chart review.    Methods  Fifty patients unexpectedly discharged to acute care underwent chart review to determine details of each  ACT .    Findings  Seven of 50  ACT  possessed new vital sign abnormalities at the 11 pm vital sign assessment the night before  ACT . None of these seven underwent  ACT  during the night shift the abnormalities were detected. Two of 50  ACT  were transferred between 11 pm and 6:59 am; both demonstrating normal vital sign at the 11 pm assessment. During study period, an estimated 5,607 11 pm vital sign assessments were performed.    Conclusions  Nighttime vital sign assessments do not seem to be a good screening tool for clinical instability in the rehabilitation hospital.    Clinical Relevance  Eliminating sleep disturbance is important to the rehabilitation inpatient as inadequate sleep hinders physical performance. Tailoring vital sign monitoring to fit patents' clinical presentation may benefit this population
Generalization capabilities of co-evolution in learning robot behavior

In this article, a co-evolutive method is used to evolve neural controllers for general obstacle-avoidance of a Braitenberg vehicle. During a first evolutionary process, Evolution Strategies were applied to generate neural controllers; the generality of the obtained behaviors was quite poor. During a second evolutionary process, a new co-evolutive method, called Uniform Co-evolution, is introduced to co-evolve both the controllers and the environment. A comparison of both methods shows that the co-evolutive approach improves the generality of controllers.Publicad
Fusing visual and inertial sensing to recover robot egomotion

A method for estimating mobile robot egomotion is presented, which relies on tracking contours in real-time images acquired with a calibrated monocular video system. After ﬁtting an active contour to an object in the image, 3D motion is derived from the affine deformations suffered by the contour in an image sequence. More than one object can be tracked at the same time yielding some different pose estimations. Then, improvements in pose determination are achieved by fusing al l these different estimations. Inertial information is used to obtain better estimates, as it introduces in the tracking algorithm a measure of the real velocity. Inertial information is also used to eliminate some ambiguities arising from the use of a monocular image sequence. As the algorithms developed are intended to be used in real-time control systems, considerations on computation costs are taken into account.This work was supported by the project 'Sistema reconfigurable para la navegación basada en visión de robots caminantes y rodantes en entornos naturales.' (00).Peer Reviewe
Using Soft Computing Techniques for Improving Foot Trajectories in Walking Machines

Walking machines have been investigated during the last 40 years and some basic\ud
techniques of this field are already well known. However, some aspects still need\ud
to be optimized. For instance, speed seems to be one of the major shortcomings of\ud
legged robots; thus, improving leg speed has been chosen as the main aim of this\ud
work. Although some algorithms for optimizing trajectory control of robot manipulators\ud
already exist, we propose a more computationally efficient method that employs\ud
fuzzy set theory to involve real dynamic effects over leg motion instead of an inaccurate\ud
mathematical model. In this article, we improve leg speed by automatically tuning\ud
the acceleration of legs. For this purpose, we define fuzzy rules based on experiments\ud
and we find the optimal acceleration for every given trajectory. A simple fuzzy inference\ud
system is used to compute the required acceleration. It is based on five rules using\ud
three linguistic variables. Final results show that foot acceleration tuning for straight\ud
trajectory generation is a suitable method for achieving accurate, smooth and fast foot\ud
movements. Also it is shown that under some conditions average leg speed can be\ud
increased up to 100% using the control methods herein proposed.Contract Grant Sponsor: CICYT (Spain).\ud
Contract Grant number: TAP1999-1080-C04-01.Peer reviewe
Visual servoing of an autonomous helicopter in \ud
urban areas using feature tracking

We present the design and implementation of a vision-based feature tracking system for an autonomous helicopter. Visual sensing is used for estimating the position and velocity of features in the image plane (urban features like windows) in order to generate velocity references for the flight control. These visual-based references are\ud
then combined with GPS-positioning references to navigate towards these features and then track them. We present results from experimental flight trials, performed in two\ud
UAV systems and under different conditions that show the feasibility and robustness of our approach
The visual compass: performance and limitations of an appearance-based method

Labrosse, F. (2006). The visual compass: performance and limitations of an appearance-based method. Journal of Field Robotics, 23 (10), 913-941In this article we present an algorithm to estimate the orientation of a robot relative to an orientation specified at the beginning of the process. This is done by computing the rotation of the robot between successive panoramic images, grabbed on the robot while it moves, using a subsymbolic method to match the images. The context of the work is Simultaneous Localization And Mapping (SLAM) in unstructured and unmodified environments. As such, very few assumptions are made about the environment and the robot's displacement. The algorithm's performance depends on the value of a number of parameters being determined to provide overall good performance of the system. The performance is evaluated in different situations (trajectories and environments) with the same parameters and the results show that the method performs adequately for its intended use. In particular, the error is shown to be drifting slowly, in fact much slower than unprocessed inertial sensors, thus only requiring infrequent realignment, for example when relocalizing in a topological map. Limitations of the proposed methods are also shown and discussed.Peer reviewe
Scan registration for autonomous mining vehicles using 3D-NDT

Scan registration is an essential subtask when building maps based on range finder data from mobile robots. The problem is to deduce how the robot has moved between consecutive scans, based on the shape of overlapping portions of the scans. This paper presents a new algorithm for registration of 3D data. The algorithm is a generalization and improvement of the normal distributions transform (NDT) for 2D data developed by Biber and Strasser, which allows for accurate registration using a memory-efficient representation of the scan surface. A detailed quantitative and qualitative comparison of the new algorithm with the 3D version of the popular ICP (iterative closest point) algorithm is presented. Results with actual mine data, some of which were collected with a new prototype 3D laser scanner, show that the presented algorithm is faster and slightly more reliable than the standard ICP algorithm for 3D registration, while using a more memory efficient scan surface representation
MARTE: Technology development and lessons learned from a mars drilling mission simulation

29 pages, 21 figures, 2 tables.-- ISI Article Identifier: 000250768000006.-- Special issue: Mining Robotics.The NASA Mars Astrobiology Research and Technology Experiment (MARTE) performed a field test simulating a robotic drilling mission on Mars in September 2005. The experiment took place in Minas de Riotinto in southwestern Spain, a highly relevant Mars analog site. The experiment utilized a 10 m class dry auger coring drill, a robotic core sample handling system, onboard science and life detection instruments, and a borehole inspection probe, all of which were mounted to a simulated lander platform. Much of the operation of the system was automated, and the resulting data were transmitted via satellite to remote science teams for analysis. The science team used the data to characterize the subsurface geology and to search for signs of life. Based on the data being received and operational constraints, the science team also directed the daily operation of the equipment. The experiment was highly successful, with the drill reaching over 6 m in depth in 23 days of simulated mission. The science team analyzed remote sensing data obtained from 28 cores and detected biosignatures in 12 core subsamples. This experiment represents an important first step in understanding the technology and operational requirements for a future Mars drilling mission. In the past there have been numerous rover field tests that have helped guide the design and implementation of the highly successful rover missions to Mars. However, a drilling mission potentially adds a new level of complexity, and it is important to understand the associated challenges. This paper documents the design of the experimental system, highlighting some of the more important design criteria and design trades. It also discusses the results of the field testing and lists some of the key technological lessons learned.MARTE was jointly funded by the NASA Astrobiology Science and Technology for Exploring\ud
Planets (ASTEP) program through NRA 02-OSS-01. Partial funding for automation was provided by\ud
the NASA Intelligent Systems program. Spanish participation in MARTE was funded by the Centro\ud
de Astrobiología. We also thank the Museo Minero de Rio Tinto, Spain and the staff of the Vazquez Díaz Hotel in Nerva, Spain for providing field facilities and logistical support to the MARTE project.Peer reviewe
Autonomous science for an ExoMars Rover-like mission

Special Issue: Special Issue on Space Robotics, Part II Mark Woods, Andy Shaw, Dave Barnes, Dave Price, Derek Long, Derek Pullan, Autonomous science for an ExoMars Rover-like mission, Journal of Field Robotics, Volume 26 Issue 4 (April 2009), pp 358-390. Sponsorship: STFCIn common with other Mars exploration missions, human supervision of Europe's ExoMars Rover will be mostly indirect via orbital relay spacecraft and thus far from immediate. The gap between issuing commands and witnessing the results of the consequent rover actions will typically be on the order of several hours or even sols. In addition, it will not be possible to observe the external environment at the time of action execution. This lengthens the time required to carry out scientific exploration and limits the mission's ability to respond quickly to favorable science events. To increase potential science return for such missions, it will be necessary to deploy autonomous systems that include science target selection and active data acquisition. In this work, we have developed and integrated technologies that we explored in previous studies and used the resulting test bed to demonstrate an autonomous, opportunistic science concept on a representative robotic platform. In addition to progressing the system design approach and individual autonomy components, we have introduced a methodology for autonomous science assessment based on terrestrial field science practice.Peer reviewe
Mixed kinematic and dynamic sideslip angle observer for accurate control of fast off-road mobile robots

Automation in outdoor applications (farming, surveillance, military activities, etc.) requires highly accurate control of mobile robots, at high speed, although they are moving on low-grip terrain. To meet such expectations, advanced control laws accounting for natural ground specificities (mainly sliding effects) must be derived. In previous work, adaptive and predictive control algorithms, based on an extended kinematic representation, have been proposed. Satisfactory experimental results have been reported (accurate to within ±10 cm, whatever the grip conditions), but at limited velocity (below 3 m·s-1). Nevertheless, simulations reveal that control accuracy is decreased when vehicle speed is increased (up to 10 m·s-1). In particular, oscillations are observed at curvature transition. This drawback is due to delays in sideslip angle estimation, unavoidable at high speed because only an extended kinematic representation was used. In this paper, a mixed backstepping kinematic and dynamic observer is designed to improve observation of these variables: the slow-varying data are still estimated from a kinematic representation, which is then injected into a dynamic observer to supply reactive and reliable sliding variable (namely sideslip angle) estimation, without increasing the noise level. The algorithm is evaluated via advanced simulations (coupling Adams and MatLab software) investigating high-speed capabilities. Actual experiments at lower speed (experimental platform maximum velocity) demonstrate the benefits of the proposed approach