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arXiv 2022年

作者： Wildhagen, Stefan Pezzutto, Matthias Schenato, Luca Allgöwer, Frank University of Stuttgart Institute for Systems Theory and Automatic Control Germany Université Libre de Bruxelles Service d’Automatique et d’Analyse des Systèmes Belgium University of Padova Department of Information Engineering Italy

Networked control systems typically come with a limited communication bandwidth and thus require special care when designing the underlying control and triggering law. A method that allows to consider hard constraints on the communication traffic as well as on states and inputs is self-triggered model predictive control (MPC). In this scheme, the optimal length of the sampling interval is determined proactively using predictions of the system behavior. However, previous formulations of self-triggered MPC have neglected the widespread phenomenon of packet loss, such that these approaches might fail in practice. In this paper, we present a novel self-triggered MPC scheme which is robust to bounded packet loss by virtue of a min-max optimization problem. We prove recursive feasibility, constraint satisfaction and convergence to the origin for any possible packet loss realization consistent with the boundedness constraint, and demonstrate the advantages of the proposed scheme in a numerical example. Copyright © 2022, The Authors. All rights reserved.

关键词： Model predictive control

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A control framework for autonomous e-scooters

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IFAC-PapersOnLine 2021年第2期54卷 252-258页

作者： Raffaele Soloperto Philipp Wenzelburger David Meister Dominik Scheuble Veronika S.M. Breidohr Frank Allgöwer University of Stuttgart Institute for Systems Theory and Automatic Control Pfaffenwaldring 9 70569 Stuttgart Germany University of Stuttgart Faculty 7: Engineering Design Production Engineering and Automotive Engineering Pfaffenwaldring 9 70569 Stuttgart Germany

In this paper, we address the core challenges of self-stabilization, obstacle detection, and collision avoidance arising when developing autonomous electric scooters for sharing systems. In particular, we firstly demonstrate how an e-scooter can balance itself by the usage of a reaction wheel combined with a braking mechanism. Secondly, we show how a depth-camera can be utilized to generate a grid map representation of the environment surrounding the e-scooter and how this can be used to design a computationally tractable algorithm which ensures obstacle avoidance as well as path following. Finally, the goal of this paper is to provide a starting point for the development of autonomous e-scooters for sharing systems by combining approaches from various research communities in a common application framework.

关键词： E-scooters Self-stabilization Collision avoidance Obstacle detection Smart-mobility

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Seismic protection of multi-story structures with novel vibration absorption devices combining negative stiffness and inerter 8

Seismic protection of multi-story structures with novel vibr...

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8th International Conference on Computational Methods in Structural Dynamics and Earthquake engineering, COMPDYN 2021

作者： Kapasakalis, Konstantinos A. Florakis, Georgios I. Antoniadis, Ioannis A. Sapountzakis, Evangelos J. Institute of Structural Analysis and Antiseismic Research School Civil Engineering National Technical University of Athens Zografou Campus AthensGR-157 80 Greece Mechanical Design and Control Systems Section Mechanical Engineering Department National Technical University of Athens Zografou Campus AthensGR-157 80 Greece

This paper proposes a Stiff Seismic Base Absorber (SBA). An inerter is first implemented, connecting directly the structure to the ground. This results to the decrease of the natural frequency of the structure, without the decrease of the structural stiffness. Parallel, an extension of the KDamper is used, in order to increase the apparent damping behavior of the inerter. A negative stiffness (NS) element connects the additional mass of the SBA to the structure and a positive stiffness element the additional mass to the base. Also, an artificial damper is placed in parallel with each stiffness element. The design of the SBA is based on an appropriate optimization approach, which includes the following novel features: i) the SBA foresees variation in all stiffness elements, ii) the optimal system parameters are selected based on engineering criteria with proper constraints and limitations to the system dynamic responses, iii) the earthquake input motion is selected according to the seismic design codes, iv) for the NS element, a displacement-dependent non-linear mechanism is proposed realized by a pre-compressed leaf spring instead of conventional coil springs. Compared to other vibration absorbers, the SBA presents a number of advantages. An improved superstructure dynamic behavior is observed combined with small base displacements, in the order of a few centimeters. The drastically reduced base displacements render the implementation of the SBA feasible using conventional structural elements. As a result, the SBA is a possible retrofitting option for seismic protection. © 2021 COMPDYN Proceedings.

关键词： Damping

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Practical and Rigorous Uncertainty Bounds for Gaussian Process Regression

arXiv

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arXiv 2021年

作者： Fiedler, Christian Scherer, Carsten W. Trimpe, Sebastian Intelligent Control Systems Group Max Planck Institute for Intelligent Systems Germany Mathematical Systems Theory University of Stuttgart Germany Institute for Data Science in Mechanical Engineering RWTH Aachen University Germany

Gaussian Process Regression is a popular nonparametric regression method based on Bayesian principles that provides uncertainty estimates for its predictions. However, these estimates are of a Bayesian nature, whereas for some important applications, like learning-based control with safety guarantees, frequentist uncertainty bounds are required. Although such rigorous bounds are available for Gaussian Processes, they are too conservative to be useful in applications. This often leads practitioners to replacing these bounds by heuristics, thus breaking all theoretical guarantees. To address this problem, we introduce new uncertainty bounds that are rigorous, yet practically useful at the same time. In particular, the bounds can be explicitly evaluated and are much less conservative than state of the art results. Furthermore, we show that certain model misspecifications lead to only graceful degradation. We demonstrate these advantages and the usefulness of our results for learning-based control with numerical examples. Copyright © 2021, The Authors. All rights reserved.

关键词： Uncertainty analysis

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Do We Run Large-scale Multi-Robot systems on the Edge? More Evidence for Two-Phase Performance in System Size Scaling

Do We Run Large-scale Multi-Robot Systems on the Edge? More ...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Jonas Kuckling Robin Luckey Viktor Avrutin Andrew Vardy Andreagiovanni Reina Heiko Hamann Department of Computer and Information Science University of Konstanz Konstanz Germany Centre for the Advanced Study of Collective Behaviour University of Konstanz Germany Institute of Computer Engineering University of Lübeck Lübeck Germany Institute for Systems Theory and Automatic Control University of Stuttgart Stuttgart Germany Department of Computer Science and the Department of Electrical and Computer Engineering Memorial University of Newfoundland St. John’s Canada IRIDIA Université Libre de Bruxelles Brussels Belgium

ISBN: (数字)9798350384574

ISBN: (纸本)9798350384581

With increasing numbers of mobile robots arriving in real-world applications, more robots coexist in the same space, interact, and possibly collaborate. Methods to provide such systems with system size scalability are known, for example, from swarm robotics. Example strategies are self-organizing behavior, a strict decentralized approach, and limiting the robot-robot communication. Despite applying such strategies, any multi-robot system breaks above a certain critical system size (i.e., number of robots) as too many robots share a resource (e.g., space, communication channel). We provide additional evidence based on simulations, that at these critical system sizes, the system performance separates into two phases: nearly optimal and minimal performance. We speculate that in real-world applications that are configured for optimal system size, the supposedly high-performing system may actually live on borrowed time as it is on a transient to breakdown. We provide two modeling options (based on queueing theory and a population model) that may help to support this reasoning.

关键词： Limiting System performance Space communications Scalability Sociology Swarm robotics Mobile robots

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Functional Simulation of automotive Lidar and Camera Sensors

Functional Simulation of automotive Lidar and Camera Sensors

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AmE 2020 - Automotive meets Electronics;11th GMM-Symposium

作者： Katharina Bartsch Niklas Stannartz Manuel Schmidt Torsten Bertram TU Dortmund University Institute of Control Theory and Systems Engineering

ISBN: (纸本)9783800752027

This paper presents a method to simulate various automotive sensors based on functional properties. An extraction of the road users in the surroundings is determined by Deep Learning based object detectors to generate a sufficient perception of the vehicle environment. Simultaneously, it is important that the data processing runs in real time and with a high detection accuracy to ensure a safe maneuvering of the vehicle. For this reason the object detectors considered in this paper are the single shot multibox detector with MobileNet as base network for image processing and the Sparsely Embedded Convolutional Detection detector for lidar point clouds. The dataset used for the evaluation is KITTI. The detection accuracies for different object distances are investigated and compared. To create a functional simulation for the different sensor systems, the evaluation of the object detection for various sensor types is used to model the respective sensor behavior and its properties. The modeled object detectors are evaluated with respect to the detection accuracies of the real detectors. These sensor models can then be used in simulations for different sensor topologies.

关键词： detector Sensors simulating Object detection Lidar Road users Sensor systems vehicle Automotive sensors automotive engineering

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Stiff dynamic absorbers for the vertical seismic protection of structures 8

Stiff dynamic absorbers for the vertical seismic protection ...

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8th International Conference on Computational Methods in Structural Dynamics and Earthquake engineering, COMPDYN 2021

作者： Kalogerakou, M.E. Kapasakalis, K.A. Antoniadis, I.A. Sapountzakis, E.J. Institute of Structural Analysis and Antiseismic Research School of Civil Engineering National Technical University of Athens Zografou Campus AthensGR-157 80 Greece Dynamics and Structures Laboratory Mechanical Design and Control Systems Section Mechanical Engineering Department National Technical University of Athens Zografou Campus AthensGR-157 80 Greece

The majority of the existing seismic protection systems and techniques are related to horizontal ground motions, while there are only a few vertical seismic protection systems. The main reason is due to the conflict concerning the demand for isolation stiffness. More specifically, a vertical isolated system must have sufficient vertical rigidity to sustain the weight of the isolated object/system and retain the static vertical deflection in reasonable limits. On the other hand, the isolated system must also have enough flexibility to isolate the accelerations. In order to overcome this difficulty, a novel vertical seismic absorber system is proposed, that combines a Quasi-Zero Stiffness (QZS) design including negative stiffness elements, an enhanced Tunned Mass Damper (TMD) and an inerter. The QZS oscillator manages to maintain the vertical rigidity of the structure, the inerter manages to reduce the frequency of the system, without weakening the structure or increase the seismic load and the TMD is responsible for absorbing the external excitations, significantly increasing the effective damping. This way, the dynamic behavior of the system is improved, in terms of absolute accelerations, and simultaneously, the static settlements are retained at any desired level. The design is based on engineering criteria, and the excitation input is selected according to the seismic design codes. © 2021 COMPDYN Proceedings.

关键词： Damping

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Consistent Kalman flters for nonlinear uncertain systems over sensor networks

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control theory and Technology 2020年第4期18卷 399-408页

作者： Xingkang He Wenchao Xue Haitao Fang Xiaoming Hu Division of Decision and Control Systems School of Electrical Engineering and Computer ScienceKTH Royal Institute of Technology10044 StockholmSweden LSC NCMISAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China Optimization and Systems Theory Department of MathematicsKTH Royal Institute of Technology10044 StockholmSweden

In this paper,we study how to design filters for nonlinear uncertain systems over sensor *** intoduce two Kalmantype nonlinear fitrs in centralied and dstrbute ***,the tuning method for the parameters of the filteres is established to ensure the consistency,i.e..the mean square error is upper bounded by a known parameter matrix at each *** apply the consistent fiters to the track to-track association analysis of multi targets with uncertain dynamics.A novel track to-track asocaion algoritm is proposed to idenify whether two tracks are from the same *** is proven that the resulting probability of *** is lower than the desired *** simulations on *** track association are given to show the ffetives of the methods.

关键词： Kalman fiter Consistencey Distributed fiter Track-to-rack asociation

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Knowledge-aware Graph Transformer for Pedestrian Trajectory Prediction

Knowledge-aware Graph Transformer for Pedestrian Trajectory ...

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International Conference on Intelligent Transportation

作者： Yu Liu Yuexin Zhang Kunming Li Yongliang Qiao Stewart Worrall You-Fu Li He Kong Shenzhen Key Laboratory of Control Theory and Intelligent Systems Southern University of Science and Technology (SUSTech) Shenzhen China Department of Mechanical Engineering City University of Hong Kong Hong Kong SAR China School of Automation Guangdong Polytechnic Normal University Guangzhou China Australian Centre for Field Robotics The University of Sydney NSW Australia Australian Institute for Machine Learning The University of Adelaide SA Australia Department of Mechanical Engineering City University of Hong Kong Hong Kong SAR China Shenzhen Key Laboratory of Control Theory and Intelligent Systems SUSTech Shenzhen China Guangdong Provincial Key Laboratory of Human-Augmentation Rehabilitation Robotics in Universities SUSTech Shenzhen China

Predicting pedestrian motion trajectories is crucial for path planning and motion control of autonomous vehicles. Accurately forecasting crowd trajectories is challenging due to the uncertain nature of human motions in different environments. For training, recent deep learning-based prediction approaches mainly utilize information like trajectory history and interactions between pedestrians, among others. This can limit the prediction performance across various scenarios since the discrepancies between training datasets have not been properly incorporated. To overcome this limitation, this paper proposes a graph transformer structure to improve prediction performance, capturing the differences between the various sites and scenarios contained in the datasets. In particular, a self-attention mechanism and a domain adaption module have been designed to improve the generalization ability of the model. Moreover, an additional metric considering cross-dataset sequences is introduced for training and performance evaluation purposes. The proposed framework is validated and compared against existing methods using popular public datasets, i.e., ETH and UCY. Experimental results demonstrate the improved performance of our proposed scheme.

关键词：

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Steady state behavior of the free recall dynamics of working memory

arXiv

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arXiv 2022年

作者： Li, Tianhao Liu, Zhixin Liu, Lizheng Hu, Xiaoming Key Laboratory of Systems and Control Academy of Mathematics and Systems Science Chinese Academy of Sciences School of Mathematical Sciences University of Chinese Academy of Sciences Beijing100190 China Academy for Engineering and Technology Fudan University Shanghai200433 China Optimization and Systems Theory KTH Royal Institute of Technology Stockholm10044 Sweden

This paper studies a dynamical system that models the free recall dynamics of working memory. This model is a modular neural network with n modules, named hypercolumns, and each module consists of m minicolumns. Under mild conditions on the connection weights between minicolumns, we investigate the long-term evolution behavior of the model, namely the existence and stability of equilibriums and limit cycles. We also give a critical value in which Hopf bifurcation happens. Finally, we give a sufficient condition under which this model has a globally asymptotically stable equilibrium with synchronized minicolumn states in each hypercolumn, which implies that in this case recalling is impossible. Numerical simulations are provided to illustrate our theoretical results. A numerical example we give suggests that patterns can be stored in not only equilibriums and limit cycles, but also strange attractors (or chaos). Copyright © 2022, The Authors. All rights reserved.

关键词： Asymptotic stability

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