60 research outputs found
Self-tuning Fuzzy Task Space Controller for Puma 560 Robot
Get PDFSince in most robot applications the desired paths are determined in task space or Cartesian space, it is important to control the robot arm in task space. In this paper a fuzzy controller with modifiable scaling factors is proposed to control the robot end-effector in task space. The controller is a fuzzy system with a mechanism to change the scaling factors when the error is bounded under a predetermined value. The controller is designed in joint space and is developed to work space by using inverse Jacobian strategy. The simulations results on Puma 560 robot manipulator illustrate the high performance of presented control method
Energy-based shape regulation of soft robots with unactuated dynamics dominated by elasticity
No full textThis paper proposes a model-based control design approach for a broad class of soft robots, having their elastic field dominating gravity in the unactuated coordinates. To this end, we consider finite-dimensional dynamic models obtained from approximations of the system's energy. Then, we propose a general control architecture that can stabilize soft robots based on potential energy shaping. We discuss three specializations of this general architecture: a PD with mixed feedback-feedforward gravity compensation, a PD with feedforward compensation, and a saturated version of the latter. We provide a physical interpretation of the controllers, and we illustrate their applicability through simulations.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Learning & Autonomous ControlTeam Azita Dabir
On the Role of Coupled Damping and Gyroscopic Forces in the Stability and Performance of Mechanical Systems
Full text linkDamping injection is a well-studied tool in nonlinear control theory to stabilize and shape the transient of mechanical systems. Interestingly, the injection of coupled damping yielding gyroscopic forces has received far less attention. This letter aims to fill this gap for gyroscopic forces that couple actuated and unactuated coordinates. First, we establish sufficient conditions for the stability of the closed loop. Then, we provide analytic results proving that injecting coupled damping may improve the closed-loop performance. We illustrate the results via the stabilization of three mechanical systems.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Learning & Autonomous ControlTeam Azita Dabir
Have transport costs contributed to the relative decline of sub-Saharan African exports? Some preliminary empirical evidence
Full text linkFrom the mid-1950s to 1990, sub-Saharan Africa's share of global exports fell from 3.1 to under 1.2 percent, a decline that implies associated export earning losses of about $65 billion annually. Previous studies show that foreign trade barriers do not account for this poor performance. Indeed, African exports enjoy OECD tariff preferences. In the sub-Saharan African countries, too high a proportion of foreign exchange earnings is paying for Africa's high export transport costs. The authors demonstrate that relatively high transportation costs - especially for processed products - often place African exporters at a serious competitive disadvantage. African countries must use a far larger share of their foreign exchange earnings to pay for international transport services than other developing countries do - and the relative importance of those payments has been increasing. Why are Africa's transport costs so high? Ill-advised policies on the part of some African governments seem to have played a role, as their cargo reservation policies produced high"rents"for lines that have been shielded from the effects of competition. The failure to maintain or improve port and transport infrastructure has also played a role.Rural Roads&Transport,Economic Theory&Research,Transport and Trade Logistics,Common Carriers Industry,Environmental Economics&Policies,Transport and Trade Logistics,Common Carriers Industry,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Environmental Economics&Policies,Economic Theory&Research
Adaptive Fuzzy Control of Puma Robot Manipulator in Task Space with Unknown Dynamic and Uncertain Kinematic
Full text linkA In this paper, an adaptive direct fuzzy control system is presented to control the robot manipulator in task space. It is assumed that robot system has unknown dynamic and uncertain kinematic. The control system and adaption mechanism are firstly designed for joint space tracking. Then by using inverse Jacobian strategy, it is generalized for task space. After that, to overcome the problem of Jacobian matrix uncertainty, an improved adaptive control system is designed. All the design steps are illustrated by simulations
An integrated home energy management system by the load aggregator in a microgrid using the internet of things infrastructure
Get PDFSmart technologies enable the significant participation of consumers in demand-side management programs. In this paper, the management of electrical energy consumption for a set of residential houses in a microgrid by a load aggregator for a 24-h planning horizon is studied. In this study, consumption management programs are implemented on controllable equipment by sending binary codes by the load aggregator via the internet of things (IoT) infrastructure to residential sockets. To increase the level of customer convenience and provide more flexibility for consumers to participate in demand response programs, a parameter called the value of lost load (VOLL) has been introduced. According to the results, in addition to no need to use the energy management system for each residential house, only by moving shiftable loads to off-peak hours, 18.34% of energy consumption costs are saved daily. Also, from the load aggregator’s viewpoint for every 10% change in status from normal to the scheduled priority, there is a reduction of about 3.4% in the consumer’s peak-load cost. If solar arrays and storage resources are used, more than 18% of the total consumption cost can be saved
Adaptive State Feedback Control for Lipschitz Nonlinear Singular Systems
No full textSingular systems behave more powerfully in termsof dynamical system modeling than ordinary state space systems. Since thealgebraic equations in singular models can describe the systems constraints,nonlinear singular systems can present a general method for modeling andcontrol of constrained dynamical systems. This paper discusses an adaptivecontrol for nonlinear singular systems which satisfy Lipschitz condition. Adaptivemethods for singular systems are hardly ever investigated in literatures;however they are very useful methods in practice because the adaptive mechanismduring the adaptive control can adjust the controller for a system with unknownstructures and parameters to improve the system performance. The presentedcontroller is composed of a state feedback approach with adaptive gains and amechanism to adjust the gains based on the Lyapunov stability theorem. Firstthe controller is designed to stabilize the system then it is extended for the trackingproblem. A simulation on a mobile robot singular model is provided toillustrate the effectiveness of the proposed control approach
Incident indicators for freeway traffic flow models
Full text linkDeveloped in this paper is a traffic flow model parametrised to describe abnormal traffic behaviour. In large traffic networks, the immediate detection and categorisation of traffic incidents/accidents is of capital importance to avoid breakdowns, further accidents. First, this claims for traffic flow models capable to capture abnormal traffic condition like accidents. Second, by means of proper real-time estimation technique, observing accident related parameters, one may even categorize the severity of accidents. Hence, in this paper, we suggest to modify the nominal Aw-Rascle (AR) traffic model by a proper incident related parametrisation. The proposed Incident Traffic Flow (ITF) model is defined by introducing the incident parameters modifying the anticipation and the dynamic speed relaxation terms in the speed equation of the AR model. These modifications are proven to have physical meaning. Furthermore, the characteristic properties of the ITF model is discussed in the paper. A multi stage numerical scheme is suggested to discretise in space and time the resulting non-homogeneous system of PDEs. The resulting systems of ODE is then combined with receding horizon estimation methods to reconstruct the incident parameters. Finally, the viability of the suggested incident parametrisation is validated in a simulation environment.Team Azita Dabir
Public sector debt, fiscal deficits, and economic adjustment : a comparative study of six EMENA countries
Full text linkThe authors analyzed the experience of six countries (Algeria, Morocco, Pakistan, Portugal, Turkey, and Yugoslavia) and compared it with the experiences of Latin American countries. They conclude that some countries successfully absorbed the external shock of the 1980s by: (a) minimizing the effects of the external shock by combining external and domestic debt strategies; (b) adjusting their fiscal deficits; (c) experiencing a positive external shock; and (d) fostering growth by stimulating export growth and developing domestic financial markets. No single country fully implemented this strategy; those most successful in doing so were Morocco, Portugal, and Turkey. Their experience contrasts with that of some Latin American countries that experienced a similar external shock but failed to undertake fiscal adjustment and financed most of their deficit through money finance - thus experiencing high inflation levels and overburdening their private sector. In some respects, Yugoslavia had the same experience.Environmental Economics&Policies,Economic Theory&Research,Strategic Debt Management,Economic Stabilization,Public Sector Economics&Finance
Bi-level model predictive control for metro networks: Integration of timetables, passenger flows, and train speed profiles
No full textThis paper deals with the train scheduling problem for metro networks taking into account time-dependent passenger origin–destination demands and train speed profiles. The aim is to adjust train schedules online according to time-dependent passenger demands so that passenger satisfaction and operational costs are jointly optimized. An extended passenger absorption model that explicitly includes time-dependent passenger origin–destination demands is developed, where the term “absorption” refers to passengers boarding trains. Then, the passenger absorption model is extended to a bi-level framework, where passenger demands and rolling stock availability are considered at the higher level, and detailed timetables and train speed profiles are included at the lower level. A bi-level model predictive control (MPC) approach is developed for the integrated problem. The optimization problems of both levels of the bi-level MPC approach can be converted into mixed-integer linear programming (MILP) problems, which enables us to solve them with existing MILP solvers. We then show that the recursive feasibility of both the higher-level and the lower-level optimization problems can be guaranteed. In this way, we can achieve real-time train scheduling for the metro system. Numerical experiments, based on real-life data from the Beijing metro network, illustrate the effectiveness of the extended passenger absorption model and the proposed bi-level MPC approach.Team Bart De SchutterTeam Azita DabiriDelft Center for Systems and Contro
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