Dynamic Control of Mobile Multirobot Systems: The Cluster Space Formulation

The formation control technique called cluster space control promotes simplified specification and monitoring of the motion of mobile multirobot systems of limited size. Previous paper has established the conceptual foundation of this approach and has experimentally verified and validated its use for various systems implementing kinematic controllers. In this paper, we briefly review the definition of the cluster space framework and introduce a new cluster space dynamic model. This model represents the dynamics of the formation as a whole as a function of the dynamics of the member robots. Given this model, generalized cluster space forces can be applied to the formation, and a Jacobian transpose controller can be implemented to transform cluster space compensation forces into robot-level forces to be applied to the robots in the formation. Then, a nonlinear model-based partition controller is proposed. This controller cancels out the formation dynamics and effectively decouples the cluster space variables. Computer simulations and experimental results using three autonomous surface vessels and four land rovers show the effectiveness of the approach. Finally, sensitivity to errors in the estimation of cluster model parameters is analyzed.Fil: Mas, Ignacio Agustin. Instituto Tecnológico de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kitts, Christopher. Santa Clara University; Estados Unido

Deposit insurance in developing countries

About a dozen developing countries have deposit insurance systems and several others are considering establishing them. These systems are typically created to prevent contagious bank runs, to provide a formal national mechanism for handling failing banks, and to protect small depositors from losses when banks fail. Without a deposit insurance system, many developing nations in recent years have extended implicit deposit protection to depositors on a discretionary, ad hoc basis. Deposit insurance systems have several advantages over these implicit protection schemes. Deposit insurance probably gives the banking system more protection against bank runs, provides more protection for small depositors, and provides a faster, smoother administrative process. On the other hand, deposit insurance probably creates more moral hazard for depositors, thereby contributing to the erosion of market discipline and increased bank risk-taking. Deposit insurance also tends to be a more expensive mechanism for protecting depositors because it offers less freedom of action to policymakers than an implicit scheme. Finally, developing countries often do not adequately fund their deposit insurance schemes. As a result, the systems often lack credibility in the marketplace and bank supervisors may be unable to close insolvent banks because the insurer would be unable to pay off insured depositors.Banks&Banking Reform,Financial Crisis Management&Restructuring,Insurance&Risk Mitigation,Financial Intermediation,Insurance Law

Using financial futures in trading and risk management

The authors explain the features of an array of futures contracts and their basic pricing relationships and describe a few applications to show how investors and risk managers can use these contracts. Futures - and derivatives generally - allow economic agents to fine-tune the structure of their assets and liabilities to suit their risk preferences and market expectations. Futures are not a financing or investment vehicle per se, but a tool for transferring price risks associated with fluctuations in asset values. Some may use them to spread risk, others to take on risk. Financial futures (along with options) are best viewed as building blocks. Futures have facilitated the modern trend of separating conventional financial products into their basic components. They allow not only the reduction of transformation of investment risk but also the understanding and measurement of risk. The market for derivatives has grown enormously over the past decade. The value of exchange-traded eurodollar derivatives (futures and options) is equal to roughly 13 times the value of the underlying market. The volume of trading in financial futures now dwarfs the volume in traditional agricultural contracts. As emerging markets develop, given their inherently risky nature, expect financial futures to play a prominent role in risk management.Payment Systems&Infrastructure,Economic Theory&Research,International Terrorism&Counterterrorism,Banks&Banking Reform,Securities Markets Policy&Regulation,Commodities,Banks&Banking Reform,International Terrorism&Counterterrorism,Non Bank Financial Institutions,Economic Theory&Research

Central bank independence : a critical view

While expansive literature on central bank independence contains some criticisms to the independent central bank quasi-paradigm, few critical analyses have been undertaken in the years between Friedman (1962) and Posen (1994). The author extends Posen's analysis to developing countries, discussing more broadly and systematically the reasons why merely instituting an independent central bank may not bring about its professed benefits, especially in developing countries. The author argues that widely reported empirical tests that are purported to support the central bank independence proposition are plagued by potential problems of simultaneity, reverse causality, missing variables, and measurement errors. Yet one can not make positive recommendations about institutional arrangements for central banks if causality relations are not well established. Institutions are shaped by a country's record of and preferences for inflation and may have little influence on them. The author also argues that the purported benefits of an independent central bank may be eroded by conflicts between fiscal and monetary policy and by inherent problems of central bank institutional design (especially mechanisms for board appointments, public accountability, and budgetary control). If these institutional problems are not solved, problems of dynamic inconsistency traditionally associated with monetary policy are not eliminated,but merely transformed. The author suggests that the benefits of central bank independence are less likely obtained in less developed countries with shallow financial markets. Accordingly, central bank independence should be granted at a later stage in a country's financial sector development. If a less developed country seeks to establish a low-inflation path, it should concentrate on instituting financial policy reforms (such as liberalization and privatization) that bolster opposition to inflation rather than easily reversible and practically meaningless changes in legal and institutional structures. This will better ensure the sustainability -- and hence the credibility -- of the government's anti-inflation stance. Fiscal policy is often at the root of macroeconomic disturbances in developing countries. Fiscal policy is more deserving of special protection from politics because of fiscal dominance over monetary policy and its greater vulnerability to private interests. The author suggests that the solution might be to make fiscal policy less susceptible to political pressures by creating an independent fiscal board. Tying the fiscal hands of government may seem a far-fetched idea. But would it not make more sense to force discipline on fiscal policy directly rather than indirectly through monetary policy?Economic Theory&Research,National Governance,Banks&Banking Reform,Economic Stabilization,Macroeconomic Management

Product Innovations on Mobile Money

We conduct a thorough review of the state of product development and innovation on mobile money platforms. It is, in effect, a first-of-its-kind catalog of products and services that have been rolled out, are being piloted or have been proposed. In each case we discuss the specific functionalities they entail, or how they build on the basic mobile money rails. Keywords: mobile money, mobile payments, financial inclusion, electronic money, electronic payment

Time-Energy Optimal Cluster Space Motion Planning for Mobile Robot Formations

The motions of a formation of mobile robots along predetermined paths are optimized according to a tunable time-energy cost function using the cluster space approach to multiagent system specification and control. Upon path-parameterizing cluster state variables describing the geometry and pose of a multirobot group, an optimal control problem is formulated that incorporates formation dynamics and state constraints. The optimal trajectory is derived numerically via a gradient search, iterating over the initial value of one costate. A multirobot formation control simulation is then used to demonstrate the effectiveness of the technique. Results indicate that a substantial tradeoff is made between energy expenditure and motion time when considered as minimization criteria in varying proportions, allowing the operator to tailor mission trajectories according to desired levels of each

Estudio comparativo de fósforo y potasio en suelos de la Cataluña central con manejo convencional y ecológico

En el present estudi s'han analitzat els continguts de Fòsfor assimilable (mètode Olsen) i Potassi (mètode Mehlich) en sòls de 9 localitzacions de la Catalunya central. S'ha mostrejat una parcel·la per cada tipus de maneig: convencional i ecològic. De cada parcel·la es van analitzar 4 mostres compostes dels primers 30 cm de profunditat de sòl: de 0 a 10 cm, de 10 a 20 cm i de 20 cm endavant. En total s'han analitzat 202 mostres de sòl. S'ha realitzat un estudi comparatiu entre els continguts dels nutrients (ANOVA), comparant-les entre els diferents horitzons així com entre els diferents manejos. Igualment, per analitzar l'eficiència de les aportacions en cada maneig es va estudiar la correlació entre aquestes aportacions i les dades obtingudes. En les parcel·les analitzades hi ha una disponibilitat mitjana de Fòsfor assimilable (19,2 mg / kg en convencionals i 20,7 mg / kg en ecològiques) i alta de Potassi (0,62 cmol c /kg en convencionals per 0,52 cmol c /kg en ecològics) fins a 30 cm de profunditat. Malgrat les diferències en els continguts mitjos obtinguts, no presenten diferències estadísticament significatives, ni entre horitzons ni entre els diferents manejos. Els continguts trobats en les parcel·les guarden una alta correlació amb l'abonat rebut en les parcel·les ecològiques. Per contra, en les parcel·les convencionals aquesta correlació és molt febl

Distributed formation control of multiple unmanned aerial vehicles over time-varying graphs using population games

© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents a control technique based on distributed population dynamics under time-varying communication graphs for a multi-agent system structured in a leader-follower fashion. Here, the leader agent follows a particular trajectory and the follower agents should track it in a certain organized formation manner. The tracking of the leader can be performed in the position coordinates x; y; and z, and in the yaw angle phi. Additional features are performed with this method: each agent has only partial knowledge of the position of other agents and not necessarily all agents should communicate to the leader. Moreover, it is possible to integrate a new agent into the formation (or for an agent to leave the formation task) in a dynamical manner. In addition, the formation configuration can be changed along the time, and the distributed population-games-based controller achieves the new organization goal accommodating conveniently the information-sharing graph in function of the communication range capabilities of each UAV. Finally, several simulations are presented to illustrate different scenarios, e.g., formation with time-varying communication network, and time-varying formationPeer ReviewedPostprint (author's final draft

Trajectory Following with a MAV under Rotor Fault Conditions

Lately, a novel multirotor aerial vehicle capable of handling single rotor failures was presented. When a rotor fails, physically reconfiguring one of the remaining rotors of an hexarotor allows to compensate for maneuverability limitations. In this work, experimental results show the per- formance of the vehicle in a trajectory-following task in both nominal and fault conditions.Fil: Pose, Claudio Daniel. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Electronica; ArgentinaFil: Francisco Presenza. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Electronica; ArgentinaFil: Mas, Ignacio Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Giribet, Juan Ignacio. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Electronica; Argentina. Instituto Tecnológico de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentina11th International Micro Air Vehicle Competition and ConferenceMadridEspañaUniversidad Politécnica de MadridConsejo Superior de Investigaciones Científica