Showing papers on "Autonomous system (mathematics) published in 2014"

Three-dimensional chaotic autonomous system with only one stable equilibrium: Analysis, circuit design, parameter estimation, control, synchronization and its fractional-order form

Abstract: This paper proposes a three-dimensional chaotic autonomous system with only one stable equilibrium. This system belongs to a newly introduced category of chaotic systems with hidden attractors. The nonlinear dynamics of the proposed chaotic system is described through numerical simulations which include phase portraits, bifurcation diagrams and new cost function for parameter estimation of chaotic flows. The coexistence of a stable equilibrium point with a strange attractor is found in the proposed system for specific parameters values. The physical existence of the chaotic behavior found in the proposed system is verified by using the Orcard-PSpice software. A good qualitative agreement is shown between the simulations and the experimental results. Based on the Routh-Hurwitz conditions and for a specific choice of linear controllers, it is shown that the proposed chaotic system is controlled to its equilibrium point. Chaos synchronization of an identical proposed system is achieved by using the unidirectional linear and nonlinear error feedback coupling. Finally, the fractional-order form of the proposed system is studied by using the stability theory of fractional-order systems and numerical simulations. A necessary condition for the commensurate fractional order of this system to remain chaotic is obtained. It is found that chaos exists in this system with order less than three.

An open-source multi-DOF articulated robotic educational platform for autonomous object manipulation

Abstract: This research presents an autonomous robotic framework for academic, vocational and training purpose. The platform is centred on a 6 Degree Of Freedom (DOF) serial robotic arm. The kinematic and dynamic models of the robot have been derived to facilitate controller design. An on-board camera to scan the arm workspace permits autonomous applications development. The sensory system consists of position feedback from each joint of the robot and a force sensor mounted at the arm gripper. External devices can be interfaced with the platform through digital and analog I/O ports of the robot controller. To enhance the learning outcome for beginners, higher level commands have been provided. Advanced users can tailor the platform by exploiting the open-source custom-developed hardware and software architectures. The efficacy of the proposed platform has been demonstrated by implementing two experiments; autonomous sorting of objects and controller design. The proposed platform finds its potential to teach technical courses (like Robotics, Control, Electronics, Image-processing and Computer vision) and to implement and validate advanced algorithms for object manipulation and grasping, trajectory generation, path planning, etc. It can also be employed in an industrial environment to test various strategies prior to their execution on actual manipulators.

Autonomous adaptive exploration using realtime online spatiotemporal topic modeling

Abstract: The exploration of dangerous environments such as underwater coral reefs and shipwrecks is a difficult and potentially life-threatening task for humans, which naturally makes the use of an autonomous robotic system very appealing. This paper presents such an autonomous system, which is capable of autonomous exploration, and shows its use in a series of experiments to collect image data in challenging underwater marine environments. We present novel contributions on three fronts. First, we present an online topic-modeling-based technique to describe what is being observed using a low-dimensional semantic descriptor. This descriptor attempts to be invariant to observations of different corals belonging to the same species, or observations of similar types of rocks observed from different viewpoints. Second, we use the topic descriptor to compute the surprise score of the current observation. This is done by maintaining an online summary of observations thus far, and then computing the surprise score as the distance of the current observation from the summary in the topic space. Finally, we present a novel control strategy for an underwater robot that allows for intelligent traversal, hovering over surprising observations, and swimming quickly over previously seen corals and rocks.

Lyapunov-based fractional-order controller design to synchronize a class of fractional-order chaotic systems

Abstract: In this paper, a novel adaptive fractional-order feedback controller is first developed by extending an adaptive integer-order feedback controller. Then a simple but practical method to synchronize almost all familiar fractional-order chaotic systems has been put forward. Through rigorous theoretical proof by means of the Lyapunov stability theorem and Barbalat lemma, sufficient conditions are derived to guarantee chaos synchronization. A wide range of fractional-order chaotic systems, including the commensurate system and incommensurate case, autonomous system, and nonautonomous case, is just the novelty of this technique. The feasibility and validity of presented scheme have been illustrated by numerical simulations of the fractional-order Chen system, fractional-order hyperchaotic Lu system, and fractional-order Duffing system.

Analysis of a new three-dimensional system with multiple chaotic attractors

Abstract: In this paper, a new three-dimensional autonomous system with complex dynamical behaviors is reported. This new system has three quadratic nonlinear terms and one constant term. One remarkable feature of the system is that it can generate multiple chaotic and multiple periodic attractors in a wide range of system parameters. The presence of coexisting chaotic and periodic attractors in the system is investigated. Moreover, it is easily found that the new system also can generate four-scroll chaotic attractor. Some basic dynamical behaviors of the system are investigated through theoretical analysis and numerical simulation.

Variably controlled ground vehicle

Abstract: Method and apparatus for providing autonomous control of a vehicle are described. A vehicle can be manually controlled by an operator. An autonomous system can monitor the operator's control inputs and the environment of the vehicle to determine whether the control inputs result in safe operation of the vehicle. If control inputs are not safe, then the autonomous system can modify the operator's unsafe inputs into safe inputs. In various instances, the autonomous system can operate the vehicle without operator input. In the event an operator attempts to apply control inputs to the vehicle while the autonomous system is otherwise in control, the autonomous system can check to see whether the operator's inputs result in safe operation of the vehicle. If the operator's control inputs are safe, then the autonomous system can replace its autonomous commands with the operator's commands.

Tracking and Estimation of Ego-vehicle's State for Lateral Localization

Abstract: For urban driving, knowledge of ego-vehicle's position is a critical piece of information that enables ad- vanced driver-assistance systems or self-driving cars to execute safety-related, autonomous driving maneuvers. This is because, without knowing the current location, it is very hard to autonomously execute any driving maneuvers for the future. The existing solutions for localization rely on a combination of Global Navigation Satellite System (GNSS), an inertial mea- surement unit, and a digital map. However, on urban driving environments, due to poor satellite geometry and disruption of radio signal reception, their longitudinal and lateral errors are too significant to be used to guide an autonomous system. To enhance the existing system's localization capability, this work presents an effort of developing a vision-based lateral localization algorithm. The algorithm aims at reliably counting, with or without observations of lane-markings, the number road-lanes and identifying the index of the road-lane on the roadway that our vehicle happens to be driving on. Testings the proposed algorithms against inter-city and inter-state highway videos showed promising results in terms of counting the number of road-lanes and the indices of the current road-lanes. I. INTRODUCTION

Model-based autonomous system for performing dexterous, human-level manipulation tasks

Abstract: This article presents a model based approach to autonomous dexterous manipulation, developed as part of the DARPA Autonomous Robotic Manipulation Software (ARM-S) program. Performing human-level manipulation tasks is achieved through a novel combination of perception in uncertain environments, precise tool use, forceful dual-arm planning and control, persistent environmental tracking, and task level verification. Deliberate interaction with the environment is incorporated into planning and control strategies, which, when coupled with world estimation, allows for refinement of models and precise manipulation. The system takes advantage of sensory feedback immediately with little open-loop execution, attempting true autonomous reasoning and multi-step sequencing that adapts in the face of changing and uncertain environments. A tire change scenario utilizing human tools, discussed throughout the article, is used to described the system approach. A second scenario of cutting a wire is also presented, and is used to illustrate system component reuse and generality.

A mixed-initiative control system for an Aerial Service Vehicle supported by force feedback

Abstract: We present an approach to mixed initiative control for unmanned aerial vehicles (UAVs) where sliding autonomy is supported by mixed-initiative planning and haptic feedback. In the proposed framework, we assume that an autonomous system can plan and execute robotic tasks while a human operator can provide interventions when necessary receiving a force feedback. The haptic feedback is associated with the sensation about how the system is diverging from the planned operations. We tested the system at work in virtual and real environments considering simple navigation tasks. We compared the performance of human operators with or without the assistance of the force feedback. The collected results support the hypothesis that the proposed approach enables effective and intuitive mixed-initiative control.

Examining Autonomous Weapon Systems from a Law of Armed Conflict Perspective

Abstract: This chapter explores the legal implications of autonomous weapon systems and the potential challenges such systems might present to the laws governing weaponry and the conduct of hostilities. Autonomous weapon systems are weapons that are capable of selecting and engaging a target without further human operator involvement. Although such systems have not yet been fully developed, technological advances, particularly in artificial intelligence, make the appearance of such systems a distinct possibility in the years to come. Given such a possibility, it is essential to look closely at both the relevant technology involved in these cutting-edge systems and the applicable law. This chapter commences with an examination of the emerging technology supporting these sophisticated systems, by detailing autonomous features that are currently being designed for weapons and anticipating how technological advances might be incorporated into future weapon systems. A second aim of the chapter is to describe the relevant law of armed conflict principles applicable to new weapon systems, with a particular focus on the unique legal challenges posed by autonomous weapons. The legal analysis will outline how autonomous weapon systems would need to be designed for them to be deemed lawful per se, and whether the use of autonomous weapons during hostilities might be prohibited in particular circumstances under the law of armed conflict. The third and final focus of this chapter is to address potential lacunae in the law dealing with autonomous weapon systems. In particular, the author will reveal how interpretations of and issues related to subjectivity in targeting decisions and overall accountability may need to be viewed differently in response to autonomy.

Leader-following rendezvous with connectivity preservation of single-integrator multi-agent systems

Abstract: This paper studies the problem of leader-following rendezvous with connectivity preservation for a linear multiagent system where the leader system is a linear autonomous system and the follower system is a multiple single-integrator system. We develop a distributed state feedback control protocol to maintain the connectivity of the system and, at the same time, to achieve asymptotic tracking of all followers to the output of the leader system.

Grid multi-wing butterfly chaotic attractors generated from a new 3-D quadratic autonomous system

Abstract: Due to the dynamic characteristics of the Lorenz system, multi-wing chaotic systems are still confined in the positive half-space and fail to break the threshold limit. In this paper, a new approach for generating complex grid multi-wing attractors that can break the threshold limit via a novel nonlinear modulating function is proposed from the firstly proposed double-wing chaotic system. The proposed method is different from that of classical multi-scroll chaotic attractors generated by odd-symmetric multi-segment linear functions from Chua system. The new system is autonomous and can generate various grid multi-wing butterfly chaotic attractors without requiring any external forcing, it also can produce grid multi-wing both on the xz-plane and yz-plane. Basic properties of the new system such as dissipation property, equilibrium, stability, the Lyapunov exponent spectrum and bifurcation diagram are introduced by numerical simulation, theoretical analysis and circuit experiment, which confirm that the multi-wing attractors chaotic system has more rich and complicated chaotic dynamics. Finally, a novel module-based unified circuit is designed which provides some principles and guidelines for future circuitry design and engineering application. The circuit experimental results are consistent with the numerical simulation results.

Method and apparatus for a named data network within an autonomous system

Abstract: An edge node or cache server of an autonomous system (AS) can process an interest for the autonomous system. During operation, the system can receive an interest for a content object, and determines whether the local node can satisfy the interest. If the local network node does not satisfy the interest, the system determines a label indicating network information for another AS node, attaches the label to the interest, and forwards the interest to the other AS node based on the label. Further, a route server of the AS processes an interest by determining a label that corresponds to the interest, and attaching the label to the interest. The route server then forwards the interest to the egress network node based on the label, which allows the egress network node to forward the interest to the remote autonomous system based on the attached label.

An autonomous simulation based system for robotic services in partially known environments

Abstract: This paper is focused on presenting the architecture and the implementation of a semi autonomous simulation based system which is able to navigate into a partially known environment. Most of robotic agent does not support mobility according the requirements of applications. Our implementation provides a semi autonomous system which is used by an operator performing several services with better quality and low costs. The design is a module based architecture which supports the robot navigation using simulation offline software and on line at the moment when the agency percepts obstacles. The robot changes states of its mobility in real time building a new strategy to achieve the normal path received from a simulator that execute and communicate the path calculated by a simple navigational algorithm in the virtual static environment. Using a communication protocol between robotic unit and simulator software, it is possible to correct data and to improve the system behavior through a wireless communication. The physical system is tested in a laboratory environment. It is situated in a environment which is the same designed in the simulator. The robot updates its coordinates in the virtual environment and the simulation runs exactly according the navigation algorithms until the sensor module transmits to simulation software new data of obstacle presence. We evaluate the performance of the system and the results confirm an improved behavior of robotic agent in extreme situations of dynamic environment.

Towards a principle for the human supervisory control of robot weapons

Abstract: The aim is to explore the delicate balance between human reasoning and the legal requirements for the appropriate supervisory control of robot weapons. We start by examining the limitations of automatic versus aided target recognition and then review some of the relevant psychological literature on reasoning. A new framework is introduced that reframes autonomy/semi-autonomy in terms of levels of supervisory control. This allows for greater transparency in command and control and the allocation of responsibility. Finally, so-called, human supervised autonomy is assessed in terms of the supervisory control framework. Keywords: autonomous weapons, supervisory control, robot weapons, international humanitarian law, reasoning In a world where computing is taking us to new levels of automation, we must ensure that the decision to kill remains firmly under human control. Most new technological artefacts are controlled by computer chips and the technologies of violence are no exception: computer devices are becoming ubiquitous for most modern weapons and guidance control systems. Currently almost all of these weapons are under “supervisory control”, where a computer program mediates human control.1 Humans need to exercise meaningful control over weapons systems to counter many of the problems that arise from automation. The United States Department of Defense points out a number of the potential difficulties with entirely computerising robot weapon: human error, human-machine interaction failures, malfunctions, communications degradation, software coding errors, enemy cyber attacks, infiltration into the industrial supply chain, * Thank you to Maya Brehm, Article 36 and Dr. Amanda Sharkey, Computer Science, University of Sheffield for helpful comments on earlier drafts of this article. 1 Supervisory control stands in contrast to direct human control such as aiming a conventional rifle and pressing the trigger manually. 2 «The exercise of control over the use of weapons, and, concomitant responsibility and accountability for consequences are fundamental to the governance of the use of force and to the protection of the human person». Article 36 (2013) Memorandum for delegates to the Convention on Certain Conventional Weapons (CCW). Downloaded from: http://bitly.com/NJoVG3. Last accessed March 2 2014. To appear in POLITICA & SOCIETA 2014 2 jamming, spoofing, decoys, other enemy countermeasures or actions, unanticipated situations on the battlefield. 3 Even though such difficulties are well known, there is ever-increasing push by states to develop autonomous robot weapons that could move outside the reach of human supervisory control. The US has conducted advanced testing on a number of autonomous weapons platforms such as X-47b – a fast subsonic autonomous jet that can now take off and land on aircraft carriers, the Crusher – a 7 ton autonomous ground robot, and an autonomous hunting submarine. The Chinese are working on the Anjain supersonic autonomous air-to-air combat vehicle. The Russians are developing an autonomous Skat jet fighter. Israel has the autonomous Guardium ground robot and the UK is in advanced testing of the Taranis – a fully autonomous intercontinental combat aircraft. Currently, public reports on the testing of these robot devices have only been about the weapons-carrying platforms and not the weapons systems as a whole. Although autonomous robot platforms can have multiple useful purposes, arming them to select targets and attack them without deliberative human supervision raises serious legal, ethical, technical and international security concerns. The main concern of this paper is to explain the psychological underpinnings and problems with human supervisory control and to emphasise the need for a comprehensive method to ensure that appropriate deliberative human reasoning is utilised. 1. Automatic versus aided target recognition A major problem with weapons systems in which a computer program selects targets and initiates attack is that to identify and select targets requires well-defined target recognition software. Yet current automatic target recognition methods used by the military are not fit for purpose except in narrowly restricted and highly uncluttered environments. Some of examples of the main methods are: 1. Shape detection makes it possible to recognise a tank in an uncluttered environment, such as a sandy desert plain. Medium to high cluttered environments introduce an unacceptably high false alarm rate. It has proved extremely difficult to distinguish between a truck and a tank or any vehicle amongst clutter, such as 3 US Department of Defense, Autonomy in Weapon Systems, Directive 3000.09, November 21 2012. To appear in POLITICA & SOCIETA 2014 3 trees. For example, such systems use feature detection that would have difficulties distinguishing between a smooth overhanging branch and the barrel of a large gun. 2. Thermal imaging detects heat radiating from an object and shows its movement. But it would be difficult for an autonomous system to parse the image and guarantee that it can distinguish between a tank and a school bus. And certainly could not be used to distinguish between a combatant and civilians. 3. Radiation detection is used by loitering munitions, such as the Israeli Harpy, to detect radar signals and determine if they are friendly. If not then the Harpy dive bombs the radar. It is assumed that the radar is part of an anti-aircraft installation, otherwise radar detection doesn’t have any other means to determine the legitimacy

Robust chaos in autonomous time-delay system

Abstract: We consider an autonomous system constructed as modification of the logistic differential equation with delay that generates successive trains of oscillations with phases evolving according to chaotic maps. The system contains two feedback loops characterized by two generally distinct retarding time parameters. In the case of their equality, chaotic dynamics is associated with the Smale–Williams attractor that corresponds to the double-expanding circle map for the phases of the carrier of the oscillatory trains. Alternatively, at appropriately chosen two different delays attractor is close to torus with Anosov dynamics on it as the phases are governed by the Fibonacci map. In both cases the attractors manifest robustness (absence of regularity windows under variation of parameters) and presumably relate to the class of structurally stable hyperbolic attractors.

Attractor of Smale - Williams type in an autonomous distributed system

Abstract: We consider an autonomous system of partial differential equations for a one-dimensional distributed medium with periodic boundary conditions. Dynamics in time consists of alternating birth and death of patterns with spatial phases transformed from one stage of activity to another by the doubly expanding circle map. So, the attractor in the Poincare section is uniformly hyperbolic, a kind of Smale - Williams solenoid. Finite-dimensional models are derived as ordinary differential equations for amplitudes of spatial Fourier modes (the 5D and 7D models). Correspondence of the reduced models to the original system is demonstrated numerically. Computational verification of the hyperbolicity criterion is performed for the reduced models: the distribution of angles of intersection for stable and unstable manifolds on the attractor is separated from zero, i.e., the touches are excluded. The example considered gives a partial justification for the old hopes that the chaotic behavior of autonomous distributed systems may be associated with uniformly hyperbolic attractors.

Global structure of Black Holes via dynamical system

Abstract: We recast the system of Einstein field equations for Locally Rotationally Symmetric spacetimes into an autonomous system of covariantly defined geometrical variables. The analysis of this autonomous system gives all the important global features of the maximal extension of these spacetimes. We conclude that the dynamical system analysis can be a powerful mathematical tool for qualitative understanding of the global structure of spacetimes covariantly, without actually solving the field equations.

Reduction of Balance Laws in (3+1)-Dimensions to Autonomous Conservation Laws by Means of Equivalence Transformations

Abstract: A class of partial differential equations (a conservation law and four balance laws), with four independent variables and involving sixteen arbitrary continuously differentiable functions, is considered in the framework of equivalence transformations. These are point transformations of differential equations involving arbitrary elements and live in an augmented space of independent, dependent and additional variables representing values taken by the arbitrary elements. Projecting the admitted infinitesimal equivalence transformations into the space of independent and dependent variables, we determine some finite transformations mapping the system of balance laws to an equivalent one with the same differential structure but involving different arbitrary elements; in particular, the target system we want to recover is an autonomous system of conservation laws. An application to a physical problem is considered.

CASSHH – Case Adaptive SSH Honeypot

Abstract: This paper presents a novel honeypot system implemented as a deliberative agent, built by means of a Case Based Reasoning (CBR) system. The honeypot system uses as reference an existing medium interaction honeypot (Kippo) and leverages the Beliefs-Desires-Intentions (BDI) deliberative agents improved with the learning capabilities of Case Base Reasoning (CBR) technique. The main goal is to create an autonomous system capable to learn and adapt by interaction with the attackers. The preliminary experimental results show that the developed system reacts as it was foreseen.

Complete calming and stabilization of delay systems using spectral reduction

Abstract: Spectrally controllable autonomous system with commensurable delays is reduced to a system with finite spectrum. For the spectrally reduced system, a state feedback is constructed such that it ensures complete calming of the original system and stability of the closed-loop system. The distributed delay in the closed-loop system can be only in one variable. The results are illustrated by an example.

Secure Communication and Implementation for a Chaotic Autonomous System

Abstract: In this paper, a three-dimensional chaotic autonomous system is presented. The stability of the equilibrium and the conditions of the Hopf bifurcation are studied by means of nonlinear dynamics theory. Then, the circuit of chaotic system is structured out in Multisim platform by the unit circuit. The chaotic system is applied to secure communications by linear feedback synchronization control. All simulations results performed on three-dimensional chaotic autonomous system are verified the applicable of secure communication. DOI : http://dx.doi.org/10.11591/telkomnika.v12i1.4003

Remarks on integrable systems

Abstract: The problem of integrability conditions for systems of differential equations is discussed. Darboux’s classical results on the integrability of linear non-autonomous systems with an incomplete set of particular solutions are generalized. Special attention is paid to linear Hamiltonian systems. The paper discusses the general problem of integrability of the systems of autonomous differential equations in an n-dimensional space, which admit the algebra of symmetry fields of dimension ⩽ n. Using a method due to Liouville, this problem is reduced to investigating the integrability conditions for Hamiltonian systems with Hamiltonians linear in the momenta in phase space of dimension that is twice as large. In conclusion, the integrability of an autonomous system in three-dimensional space with two independent non-trivial symmetry fields is proved. It should be emphasized that no additional conditions are imposed on these fields.

On reduction of the general three-body Newtonian problem and the curved geometry

Abstract: In the framework of an idea of separation of rotational and vibrational motions, we have examined the problem of reducing the general three-body problem. The class of differentiable functions allowing transformation of the 6D Euclidean space to the 6D conformal-Euclidean space is defined. Using this fact the general classical three-body problem is formulated as a problem of geodesic flows on the energy hypersurface of the bodies system. It is shown that when the total potential depends on relative distances between the bodies, three from six ordinary differential equations of second order describing the non-integrable hamiltonian system are integrated exactly, thus allowing reducing the initial system in the phase space to the autonomous system of the 6th order. In the result of reducing of the initial Newtonian problem the geometry of reduced problem becomes curved. The latter gives us new ideas related to the problem of geometrization of physics as well as new possibilities for study of different physical problems.

Autonomous coordination of agents via attraction and repulsion

Abstract: A method of controlling movement of an agent operating within an autonomous system includes determining, using a processing device associated with the agent, at least one point of interest (POI) within an area of operation by the autonomous system; determining, from the at least one POI, a POI of highest attraction for the agent and calculating an attraction force for the agent, based on the location of the POI of highest attraction; determining proximity of the agent to one or more additional agents operating within the autonomous system, and calculating a repulsion force for the agent so as to maintain a minimum separating distance between the agent and the one or more additional agents; calculating a resultant force for the agent based on the attraction force and the repulsion force; and changing a direction of the agent based on the resultant force.

Planning and Motion Control in Autonomous Heavy-Duty Vehicles

Abstract: Autonomous driving has been an important topic of research in recent years.In this thesis we study its application to Heavy Duty Vehicles, more specically,vehicles consisting of a truck and a trailer. An overview study is done onthree fundamental steps of an autonomous driving system, planning, trajectorytracking and obstacle avoidance.In the planning part, we use RRT, and two other variants of the algorithmto nd trajectories in an unstructured environment,e.g., a mining site. Anovel path optimization post-processing technique well suited for use with RRTsolutions was also developed.For the trajectory tracking task several well-known controllers were tested,and their performance compared. An extension is proposed to one of the controllersin order to take into account the trailer. The performance evaluationwas done on scaled truck systems in the Smart Mobility Lab at KTH.The obstacle avoidance is done with the aid of a simple, yet functional ModelPredictive Controller. For this purpose, we developed dierent formulationsof the optimization problem, corresponding to distinct optimization goals andvehicle models, in order to assess both the quality of the MPC, and of theassumed truck model.The outcome of this thesis is a fully autonomous system, able to plan andmove in constrained environments, while avoiding unpredicted obstacles. Itwas implemented using a 1:32 scale remote controlled truck, commanded by adesktop computer.