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Two robust fault detection schemes are presented to detect faults affecting the thrust system of the chaser spacecraft involved in the rendezvous phase of the Mars Sample Return (MSR) mission. The idea of both proposed methods is to transform the unstructured uncertainty caused by the electronic induced delays into unknown inputs and decouple them by means of an eigenstructure assignment (EA) technique...
A universal control scheme is designed for unknown pure feedback systems, capable of guaranteeing, for any initial system condition, output tracking with prescribed performance and bounded signals in the closed loop. In this paper, by prescribed performance, it is meant that the output error converges to a predefined arbitrarily small residual set, with convergence rate no less than a certain prespecified...
Motivated by problems of uncertainty propagation and robust estimation we are interested in computing a polynomial sublevel set of fixed degree and minimum volume that contains a given semialgebraic set K. At this level of generality this problem is not tractable, even though it becomes convex e.g. when restricted to nonnegative homogeneous polynomials. Our contribution is to describe and justify...
Electronic book is usually used for users who want to read the text book with multimedia contents like video and audio. Many electronic books have been proposed with new interactive technologies such as spectacular multimedia effect, but these books lack in analog sensitivity and have only one way-based information interaction, and consequently those are inefficient for users. To solve the problem,...
Block clustering (or co-clustering or simultaneous clustering) aims at simultaneously partitioning the rows and columns of a data table to reveal homogeneous block structures. This structure can stem from the latent block model which provides a probabilistic modelling of data tables whose block patterns are defined from the row and column classes. For continuous data, each table entry is typically...
In this note, we extend the algorithm developed in [13] to the most general settings of nonlinear filtering. We rigorously show that under very mild conditions (which essentially say that the growth of the observation |h| is greater than the growth of the drift |f|), the unique nonnegative weak solution of the robust Duncan-Mortensen-Zakai (DMZ) equation can be approximated by solving the same Kolmogorov...
A relevant issue in filter design is that, in most practical situations, the system whose variables have to be estimated is not known, and a two-step procedure is adopted, based on model identification from data and filter design from the identified model. However, only approximate models can be identified from real data, and this approximation may lead to large estimation errors. In this paper, a...
This paper addresses the problem of robust optimization in large-scale networks of identical processors. General convex optimization problems are considered, where uncertain constraints are distributed to the processors in the network. The processors have to compute a maximizer of a linear objective over the robustly feasible set, defined as the intersection of all locally known feasible sets. We...
This paper develops a technique for improving the region of attraction of a robust variable horizon model predictive controller. It considers a constrained discrete-time linear system acted upon by a bounded, but unknown time-varying state disturbance. Using constraint tightening for robustness, it is shown how the tightening policy, parameterised as direct feedback on the disturbance, can be optimised...
We propose a procedure for the synthesis of control protocols for systems governed by nonlinear differential equations and constrained by temporal logic specifications. This procedure relies on a particular finite-state abstraction of the underlying continuous dynamics and a discrete representation of the external environmental signals. A two-player game formulation provides computationally efficient...
This paper deals with the problem of finding a polytopic outer approximation P* of a compact semialgebraic set S ⊆ ℝn. The computed polytope turns out to be an approximation of the linear hull of the set S. The evaluation of P* is reduced to the solution of a sequence of robust optimization problems with nonconvex functional, which are efficiently solved by means of convex relaxation techniques. Properties...
In this paper reachability/controllability properties for networked systems described by uncertain polytopic linear plants subject to time-varying state delays and input constraints are analyzed. Up to our best acknowledge, previous technical contributions on the matter were not been capable to properly address time-delay occurrences. To this end a new result making it possible to efficiently compute...
Permanent-Magnet Synchronous Machines (PMSM) with their high power density are attractive for all kinds of propulsion systems. Typically, these applications demand high torque dynamics, caused by additional demands like cancellation of drive-train torsional oscillations, slip-slide control and electronic stability control. Indirect Stator-Quantities Control (ISC) has proven its excellent torque dynamics...
The robust model-based predictive control (RMPC) formulation originally proposed in [1] ensures convergence of the state trajectory to the origin and satisfaction of operational constraints, provided that a given system of LMIs is feasible at the beginning of the control task. The largest domain of attraction of the origin under the resulting closed-loop control law can be defined as the set of all...
We calculate the cyclic entropy of a real virtual friendship network to have an insight on the degree of its robustness. Upon counting the number of cycles of different sizes in the network, a probability distribution function is resulted. An actual friendship network is found to have cyclic entropy bounded between random and small-world networks models. It has dual properties. Small world networks...
In this study, we examined the robustness of point light source approximation in lens design for light-emitting diode (LED) packages by Monte Carlo ray-tracing simulations. We modeled three representative freeform lenses first, and then simulated the lighting performance while changing the lens-to-chip size ratio (LCR). It is found that with the decrease of LCR, the lighting performances of the three...
We present an adaptive method for computing a robust polygonal approximation of an implicit curve in the plane that uses affine arithmetic to identify regions where the curve lies inside a thin strip. Unlike other interval methods, even those based on affine arithmetic, our method works on triangulations, not only on rectangular quad trees.
The paper deals with parametrization of shaping compensators (filters) ensuring the Bode's ideal control loop shape for an exactly defined class of process models. The class of essentially monotone fractional-order processes is considered. The fractional integrator is used as the optimal open loop reference model. Several aspects of shaping filter implementation on given frequency band are discussed...
In this paper, we present a robust adaptive neural network control design approach for strict-feedback nonlinear systems with uncertainties. In the controller design process, all unknown terms at intermediate steps are passed down and approximated by a single neural network at the last step. By this way, the structure of the designed controller is much simpler, and the control law and the adaptive...
This paper presents the design of a robust fractional order controller for unstable plants with only one unstable pole based on quantitative feedback theory (QFT) using Particle Swarm Optimization (PSO). In this work, a fractional-order compensator, with a flexible controller structure, is introduced into the QFT design to give a better approximation of optimum open loop in Nichols. The fractional...
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