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An asymptotically optimal indirect approach to continuous-time system identification

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arXiv 2018年

作者： González, Rodrigo A. Rojas, Cristian R. Welsh, James S. Department of Automatic Control Access Linnaeus Centre Kth Royal Institute of Technology Stockholm10044 Sweden School of Electrical Engineering and Computer Science University of Newcastle

The indirect approach to continuous-time system identification consists in estimating continuous-time models by first determining an appropriate discrete-time model. For a zero-order hold sampling mechanism, this approach usually leads to a transfer function estimate with relative degree 1, independent of the relative degree of the strictly proper real system. In this paper, a refinement of these methods is developed. Inspired by indirect PEM, we propose a method that enforces a fixed relative degree in the continuous-time transfer function estimate, and show that the resulting estimator is consistent and asymptotically efficient. Extensive numerical simulations are put forward to show the performance of this estimator when contrasted with other indirect and direct methods for continuous-time system identification. Copyright © 2018, The Authors. All rights reserved.

关键词： Continuous time systems

Non-uniqueness of stationary solutions in extremum seeking control

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arXiv 2018年

作者： Trollberg, Olle Jacobsen, Elling W. Department of Automatic Control Kth Royal Institute of Technology School of Electrical Engineering and Computer Science Osquldas v. 10 Stockholm100 44 Sweden

Extremum seeking control (ESC) is a classical adaptive control method for steady-state optimization, purely based on output feedback and without the need for a plant model. It is well known that the extremum seeking control loop, under certain mild conditions on the controller, has a stable stationary periodic solution in the vicinity of an extremum point of the steady-state input-output map of the plant. However, this is a local result only and this paper investigates whether this solution is necessarily unique given that the underlying optimization problem is convex. Wefirst derive a necessary condition that any stationary solution of the ESC loop must satisfy. For plants in which the extremum point is due to a purely static nonlinearity, such as in Hammerstein or Wiener plants, the condition involves the steady-state gradient. However, for more general plants the necessary condition involves the phase lag of the locally linearized plant, indicating the possible existence of solutions without any relationship to optimality. Combining the derived necessary condition with the existence of a local solution close to the optimum, we employ the implicit function theorem and bifurcation theory to trace out branches of stationary solutions for varying loop parameters. The focus is on solutions corresponding to limit cycles of the same period as the forcing. We derive conditions on when these branches bifurcate, resulting in multiple stationary solutions. The results show that cyclic fold bifurcations may exist, resulting in the existence of multiple stationary period one solutions, of which only one is related to the optimality conditions. We illustrate the results through an example in which the conversion in a chemical reactor is optimized using ESC. We show that at least_ve stationary solutions may exist simultaneously for realistic control parameters, and that several of these solutions are stable. One consequence of the non-uniqueness is that one in general needs to

关键词： Bifurcation (mathematics)

Image Processing Techniques in Vision-Based Robot Navigation

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Image Processing Techniques in Vision-Based Robot Navigation

International Conference on control, Artificial Intelligence, Robotics & Optimization (ICCAIRO)

作者： Rodrigo Munguia Yolanda Bolea Antoni Grau Dept. of Computer Science CUCEI University of Guadalajara Guadalajara México Automatic Control Dept. Technical University of Catalonia UPC Barcelona Spain

ISBN: (纸本)9781538695777;9781538695760

Motivated by the problems of vision-based mobile robot map building and localization, we present a comparative study of statistical methods for matching image features in a wide base line between learning and recognition phases. A general methodology called feature-class method for the problem of fast matching image features in a wide base line is described in the context of mobile robots. The objective of this work is to discuss and to show the performance of such methods in an example of visual SLAM, with experiments done with real data.

关键词： Robots Image processing Navigation Principal component analysis Conferences Artificial intelligence Optimization

Combining Lattice-Based Planning and Path Optimization in Autonomous Heavy Duty Vehicle Applications

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Combining Lattice-Based Planning and Path Optimization in Au...

IEEE Symposium on Intelligent Vehicle

作者： Rui Oliveira Mårcello Cirillo Jonas M artensson Bo Wahlberg Department of Automatic Control School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm Sweden Scania Autonomous Transport Solutions Sodertalje Sweden

Lattice-based motion planners are an established method to generate feasible motions for car-like vehicles. However, the solution paths can only reach a discretized approximation of the intended goal pose. Moreover, they can be optimal only with respect to the actions available to the planner, which can result in paths with excessive steering. These drawbacks have a negative impact when used in real systems. In this paper we address both drawbacks by integrating a steering method into a state-of-the-art lattice-based motion planner. Un- like previous approaches, in which path optimization happens in an a posteriori step after the planner has found a solution, we propose an interleaved execution of path planning and path optimization. The proposed approach can run in real-time and is implemented in a full-size autonomous truck, and we show experimentally that it is able to greatly improve the quality of the solutions provided by a lattice planner.

关键词： Lattices Planning Optimization Real-time systems Space exploration Path planning Autonomous vehicles

Handling New and Changing Requirements with Guarantees in Self-Adaptive Systems Using SimCA 12

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Handling New and Changing Requirements with Guarantees in Se...

12th IEEE/ACM International Symposium on Software Engineering for Adaptive and Self-Managing Systems, SEAMS 2017

作者： Shevtsov, Stepan Weyns, Danny Maggio, Martina Department of Computer Science Linnaeus University Sweden Department of Computer Science KU Leuven Belgium Linnaeus University Sweden Department of Automatic Control Lund University Sweden

ISBN: (纸本)9781538615508

Self-adaptation provides a principled way to deal with change during operation. As more systems with strict goals require self-adaptation, the need for guarantees in self-adaptive systems is becoming a high-priority concern. Designing adaptive software using principles from control theory has been identified as one of the approaches to provide guarantees. However, current solutions can only handle pre-specified requirements either in the form of setpoint values (S-reqs) or values to be optimized (O-reqs). This paper presents SimCA∗ that makes two contributions to control-based self-adaptation: (a) it allows the user to specify a third type of requirement that keeps a value above/below a threshold (T-reqs), and (b) it can deal with requirement sets that change at runtime (i.e., requirements can be adjusted, activated, and deactivated on the fly). SimCA∗ offers robustness to disturbances and provides adaptation guarantees. We evaluate SimCA∗ for two systems with strict goals from different domains: an underwater vehicle system used for oceanic surveillance, and a tele-assistance system for health care support. The test results demonstrate that SimCA∗ can deal with the three types of requirements (STO-reqs) operating under various types of dynamics and the set of requirements can be changed on the fly. © 2017 IEEE.

关键词： control theory

The use of clonal selection algorithm for the vehicle routing problem with time windows

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The use of clonal selection algorithm for the vehicle routin...

2017 Symposium for Young Scientists in Technology, Engineering and Mathematics, SYSTEM 2017

作者： Ogiolda, Marcin Faculty of Automatic Control Electronics and Computer Science Silesian University of Technology Akademicka 16 Gliwice44-100 Poland

Genetic and heuristics algorithms are suitable for finding solutions where classical methods fails. In this paper, clonal selection algorithm was discussed as a efficient solution for the vehicle routing problem with time windows. Moreover, variability of parameters has been tested, analyzed and discussed. Copyright © 2017 held by the authors.

关键词： Heuristic methods

Steady-state analysis of a neural-cognition based human-social behavior model

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arXiv 2018年

作者： Wei, Jieqiang Nekouei, Ehsan Wu, Junfeng Cvetkovic, Vladimir Johansson, Karl H. Department of Automatic Control School of Electrical Engineering and Computer Science KTH Royal Institute of Technology StockholmSE-100 44 Sweden College of Control Science and Engineering Zhejiang University Hangzhou China School of Architecture and the Built Environment

We consider an extension of the Rescorla-Wagner model which bridges the gap between conditioning and learning on a neural-cognitive, individual psychological level, and the social population level. In this model, the interaction among individuals is captured by a Markov process. The resulting human-social behavior model is a recurrent iterated function systems which behaves differently from the classical Rescorla- Wagner model due to randomness. Convergence and ergodicity properties of the internal states of agents in the proposed model are studied. Copyright © 2018, The Authors. All rights reserved.

关键词： Decision making

Formation control of Surface Marine Vehicles for Underwater Target Tracking Using Range Information

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Formation Control of Surface Marine Vehicles for Underwater ...

APCA International Conference on automatic control and Soft Computing (controlO)

作者： D. Moreno-Salinas N. Crasta A.M. Pascoal J. Aranda Dept. of Computer Science and Automatic Control National Distance Education University Madrid Spain Department of Electrical Engineering ISR/IST University of Lisbon Lisbon Portugal

In many of the marine applications, the availability of an accurate system to localize underwater targets using a group of surface vehicles equipped with acoustic sensors is of paramount importance. In this context, the surface vehicles must keep a well-defined formation with respect to the targets so as to maximize the range-based information available for target localization. In this paper, a target position estimation algorithm together with a simple formation control law to maintain an optimal configuration that maximizes range-related information for target localization and tracking are presented. The setup studied consists of a group of surface vehicles moving in formation and a target performing a predefined mission. The optimal formation is computed by maximizing the determinant of an appropriately defined Fisher information matrix (FIM), subject to inter-vehicle collision avoidance and vehicle manoeuvring constraints. A centralized approach for the formation control is considered, where the trajectory planning is carried out by a supervisor that computes the control actions for each agent. The formation control is complemented with a collision avoidance logic based on a discrete event law. Simulations show that this strategy leads to an interesting and well defined behavior of the formation for localization and tracking.

关键词： Target tracking Collision avoidance Robot sensing systems Estimation Position measurement Mobile robots

automatic language identification for romance languages using stop words and diacritics: Tool/experimental paper

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arXiv 2018年

作者： Truicǎ, Ciprian-Octavian Velcin, Julien Boicea, Alexandru Computer Science and Engineering Department Faculty of Automatic Control and Computers University Politehnica of Bucharest Bucharest Romania University of Lyon ERIC Laboratory Lyon 2 Lyon France

automatic language identification is a natural language processing problem that tries to determine the natural language of a given content. In this paper we present a statistical method for automatic language identification of written text using dictionaries containing stop words and diacritics. We propose different approaches that combine the two dictionaries to accurately determine the language of textual corpora. This method was chosen because stop words and diacritics are very specific to a language, although some languages have some similar words and special characters they are not all common. The languages taken into account were romance languages because they are very similar and usually it is hard to distinguish between them from a computational point of view. We have tested our method using a Twitter corpus and a news article corpus. Both corpora consists of UTF-8 encoded text, so the diacritics could be taken into account, in the case that the text has no diacritics only the stop words are used to determine the language of the text. The experimental results show that the proposed method has an accuracy of over 90% for small texts and over 99.8% for large texts. Copyright © 2018, The Authors. All rights reserved.

关键词： Natural language processing systems