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American Control Conference (ACC)

作者： J. Guldner V.I. Utkin H. Hashimoto F. Harashima Institute for Robotics and System Dynamics DLR Wessling Germany Department of Electrical Engineering Ohio State Uinversity Columbus OH USA Institute of Industrial Science Tokyo University Minato Tokyo Japan

Artificial potential fields have enjoyed growing popularity for path planning and collision avoidance both of robot manipulators and mobile robots. Although many artificial potential fields have been proposed. Few works discuss suitable control for tracking the gradient of an artificial potential field. This deficit is surprising since good tracking control is vital for successful implementation of the artificial potential field method. This paper extends previous results of a sliding mode control strategy for fully actuated holonomic robots to gradient tracking of non-holonomic mobile robots.

关键词： Mobile robots Sliding mode control Wheels Service robots Manipulator dynamics Electrical equipment industry Path planning Collision avoidance Force control Torque control

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Multi-Agent Reinforcement Learning for Cooperative Vehicle Motion Control

Multi-Agent Reinforcement Learning for Cooperative Vehicle M...

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International Conference on Intelligent Transportation

作者： Kenan Ahmic Johannes Ultsch Jonathan Brembeck Darius Burschka Institute of System Dynamics and Control at the German Aerospace Center (DLR) Wessling Germany Chair of Robotics Artificial Intelligence and Embedded Systems Technical University of Munich (TUM) Munich Germany

ISBN: (数字)9798331505929

ISBN: (纸本)9798331505936

The longitudinal and lateral low-level motion control of multiple vehicles within a platoon is a challenging task, since several different control objectives need to be solved: (i) Each vehicle in the platoon needs to follow the reference path, (ii) the leading vehicle needs to drive with a desired reference velocity, and (iii) the following vehicles need to maintain a safe spacing distance to their respective preceding vehicle. Typically, several distinct controllers are developed for each task individually, which increases both the engineering effort as well as the susceptibility to errors. We address this issue and present a cooperative low-level vehicle motion controller based on Multi-Agent Reinforcement Learning (MARL) that is able to solve all of the above-mentioned control objectives for both the leading vehicle and the following vehicles. Therefore, we apply parameter sharing within MARL to update a single control policy in a centralized fashion using the experiences of all vehicles in the environment. Additionally, we utilize the concept of agent indication during the training process and enable the policy to specialize on the control objectives of the vehicle it is currently controlling. This leads to a unifying control approach and makes the development of further controllers redundant. The simulative assessment demonstrates the effectiveness of learned policy and shows that it is able to successfully solve all of the above-mentioned control objectives for both vehicles roles, even on unseen paths.

关键词： Training Process control Reinforcement learning Drives Vectors Robustness Collision avoidance Intelligent transportation systems

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Periodic disturbance rejection of a PMSM with adaptive control algorithms

Periodic disturbance rejection of a PMSM with adaptive contr...

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IEEE International Conference on Electric Machines and Drives (IEMDC)

作者： Sebastian Maier Johann Bals Marc Bodson Department of System Dynamics and Control Institute of Robotics and Mechatronics German Aerospace Center Wessling Germany Department of Electrical and Computer Engineering University of Utah Salt Lake UT USA

Permanent magnet synchronous motors (PMSMs) produce a parasitic oscillating torque due to several reasons. This contribution cancels the oscillating torque with adaptive control algorithms. Therefore a mathematical model of the PMSM is necessary. A model with nonlinear dynamics and a Fourier approach for the ripples is used as a mathematical description. Through comparisons between measured data and simulated data it is shown that the model assumptions are valid. The adaptive algorithm is implemented as an add-on controller to the already existing control system which consists of a feedforward part and a basis controller. The challenge is that the closed loop system has a resonant frequency and the algorithm should have the same performance for all frequencies. Experimental results show the performance and convergence of the adaptive algorithm at constant and non constant velocity.

关键词： Torque Mathematical model Transfer functions Control systems Feedforward neural networks Equations Adaptation models

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Qualification of the MMX Rover Locomotion Subsystem for the Martian Moon Phobos

Qualification of the MMX Rover Locomotion Subsystem for the ...

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IEEE Conference on Aerospace

作者： Stefan Barthelmes Ralph Bayer Wieland Bertleff Markus Bihler Fabian Buse Maxime Chalon Günther Geyer Franz Hacker Cynthia Hofmann Roman Holderried Alexander Kolb Erich Krämer Viktor Langofer Roy Lichtenheldt Sascha Moser André Fonseca Prince Kaname Sasaki Hans-Jürgen Sedlmayr Juliane Skibbe Bernhard Vodermayer German Aerospace Center (DLR) Institute of System Dynamics and Control Weßling German Aerospace Center (DLR) Institute of Robotics and Mechatronics Weßling German Aerospace Center (DLR) Institute of Space Systems Bremen

Planetary rovers have proven their function and value for the Earth moon as well as Mars in the past decades. While these celestial bodies have a gravity of the same order of magnitude as the Earth, wheeled locomotion has never been performed on a body with much lower gravity. Within the Japanese Martian Moon eXploration (MMX) mission, a wheeled rover will land on the Martian Moon Phobos with a gravity of about 1/2000 of the Earth gravity. The Robotic and Mechatronics Center of the German Aerospace Center (DLR-RMC) has designed and built the locomotion subsystem (LSS) for this rover. As the first ever driving gear for milli-gravity, the LSS needed to undergo a comprehensive qualification campaign. Due to the very challenging timeline of this project, the extent of the campaign needed to be carefully tailored to the needs of the mission. This work describes the concept of the verification including some crucial tailoring choices that have been made. The individual domains of verification are then described in detail with their scope, setup, procedure and results. The goal of this publication is to give a good overview and a detailed insight into the verification of the LSS for milli-gravity. Besides follow-up missions to Phobos, this work is also a good foundation for the qualification of future driving gears for low gravity environments or small rovers in general.

关键词： Earth Space vehicles Mars Mechatronics Gears Moon Mobile robots

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New Generalized ESPRIT for Direction Estimation and Its Mathematical Link to RARE Method

New Generalized ESPRIT for Direction Estimation and Its Math...

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2012 IEEE 11th International Conference on Signal Processing(ICSP 2012)

作者： Guangmin Wang Jingmin Xin Jiayi Wu Jiasong Wang Nangning Zheng Akira Sano Institute of Artificial Intelligence and Robotics Xi'an Jiaotong University Xi'an Jiaotong University Suzhou Academy State Key Laboratory of Astronautic Dynamics Department of System Design Engineering Keio University

The generalized ESPRIT （GESPRIT） method extends the conventional ESPRIT estimator to estimate the directions-of-arrival （DOAs） of multiple incident signals by using the array with more general geometrical configurations, where the translational invariance structure is not required. Unfor-tunately, the GESPRIT has serious ambiguous DOA estimates in some scenarios, and its performance degrades severely at low signal-to-noise ration （SNR） and with a small number of snapshots. Although a polynomial version of a new GESPRIT （NGESPRIT） method was given, but its derivation and estimation performance are unavailable in published literature. In this paper, in order to overcome the ambiguity of the GESPRIT and improve the estimation performance, the NGESPRIT method is derived explicitly. Moreover, the equivalence between the proposed NGESPRIT method and the rank reduction （RARE） method is clarified, while the former is more computationally efficient than the latter. Finally the effectiveness of the NGESPRIT method is substantiated through numerical examples.

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Low Complexity Subspace-Based Two-Dimensional Direction-of-Arrivals Tracking of Multiple Targets

Low Complexity Subspace-Based Two-Dimensional Direction-of-A...

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2012 IEEE 11th International Conference on Signal Processing(ICSP 2012)

作者： Changnong Liu Guangmin Wang Jingmin Xin Jiasong Wang Nanning Zheng Akira Sano Institute of Artificial Intelligence and Robotics Xi'an Jiaotong University Xi'an Jiaotong University Suzhou Academy State Key Laboratory of Astronautic Dynamics Department of System Design Engineering Keio University

This paper deals with the problem of tracking the two-dimensional (2-D) direction-of-arrivals (DOAs) (i.e., azimuth and elevation angles) of multiple moving targets with crossover points on their trajectories, and we propose an new computationally efficient subspace-based 2-D DOA tracking algorithm for the L-shaped sensor array structured by two uniform linear arrays (ULAs). First, a new computationally efficient cross-correlation based 2-D DOA estimation with automatic pairmatching (CODEC) batch method is developed for noncoherent narrowband signals, where the computationally expensive procedures of eigendecomposition in subspace estimation and pair-matching of the estimated azimuth and elevation angles are avoided. Then a new 2-D DOA tracking algorithm is proposed, the association of the estimated azimuth and elevation angles at two successive time instants is accomplished by employing a dynamic mode and the Luenberger state observer. The simulation results show that the proposed tracking algorithm has good adaptability and tracking capability.

关键词： direction estimation, eigendecomposition, pair-matching, uniform linear array, state observer

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Application of nonlinear disturbance decoupling to active car steering

Application of nonlinear disturbance decoupling to active ca...

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1999 European Control Conference, ECC 1999

作者： Aneke, N.P.I. Ackermann, J. Bunte, T. Nijmeijer, H. Eindhoven University of Technology Faculty of Mechanical Engineering P.O. Box 513 Eindhoven5600 MB Netherlands DLR Oberpfaffenhofen Institute of Robotics and System Dynamics P.O. Box 1116 WesslingD-82230 Germany University of Twente Faculty of Mathematical Sciences P.O.Box 217 Enschede7500 AE Netherlands

ISBN: (纸本)9783952417355

A control design approach is presented for active steering of front wheel steered vehicles. The approach consists of the application of disturbance decoupling via state-derivative feedback. Simulations with the resulting controller show that the use of state-derivative information may considerably enhance vehicle safety, in particular under adverse operating conditions such as icy roads. © 1999 EUCA.

关键词： Vehicle safety

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Two-Dimensional Direction Tracking of Coherent Signals with Two Parallel Uniform Linear Arrays

Two-Dimensional Direction Tracking of Coherent Signals with ...

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2012 IEEE 11th International Conference on Signal Processing(ICSP 2012)

作者： Jiayi Wu Jingmin Xin Guangmin Wang Jiasong Wang Nangning Zheng Akira Sano Institute of Artificial Intelligence and Robotics Xi'an Jiaotong University Xi'an Jiaotong University Suzhou Academy State Key Laboratory of Astronautic Dynamics Department of System Design Engineering Keio University

In some practical applications, the two-dimensional (2-D) direction-of-arrivals (DOAs) of incident signals should be estimated adaptively or the time-varying 2-D DOAs should be tracked promptly from the noisy array data, and multipath propagation is usually encountered due to various reflections, where the incident signals are caused to be coherent (i.e., fully correlated). In this paper, we propose a new computationally efficient subspace-based adaptive algorithm for 2-D DOA tracking of multiple coherent incident signals by using two parallel uniform linear arrays (ULAs). In the proposed algorithm, the computationally expensive eigendecomposition and the pair-matching of estimated 2-D DOAs are avoided, and the association of estimated 2-D DOAs at two successive time instants is accomplished by employing the Luenberger observer and dynamic model of direction trajectories. The effectiveness of the proposed algorithm are verified through numerical examples.

关键词： Two-dimensional direction-of-arrival estimation adaptive filtering algorithm pair-matching Luenberger observer

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Robust Stabilization of Car Steering dynamics

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IFAC Proceedings Volumes 1999年第2期32卷 3283-3288页

作者： Long Wang J. Ackermann Center for Systems and Control Department of Mechanics and Engineering Science Peking University Beijing 100871 Fax: +86-10-51881688 China Institute of Robotics and System Dynamics German Aerospace Research Center DLR-Oberpfaffenhofen D-82230 Wessling Germany

In this paper, by exploiting the intrinsic structure of system equations and uncertainties, we first establish a nonconservative PID stabilization criterion for driver support systems. We then show some interesting results on positivity and connections of PID controllers. Finally, some extreme point results on PID α-stabilization are obtained. These results give certain explanations and justifications for the simulation results performed at German Aerospace Research Center.

关键词： Robust Control Car Steering dynamics Parameter Space PID Controllers Stabilization Extreme Point Results

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Estimation of the number of narrowband signals in the presence of multipath propagation

Estimation of the number of narrowband signals in the presen...

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Sensor Array and Multichannel Signal Processing Workshop

作者： Hao Tao Jingmin Xin Jiasong Wang Nanning Zheng Akira Sano Institute of Artificial Intelligence and Robotics Xian Jiaotong University Xi'an China State Key Laboratory of Astronautic Dynamics Xi'an China Department of System Design Engineering Keio University Yokohama Japan

In this paper, we address with the problem of detection the number of narrowband signals impinging on a uniform linear array (ULA) in the presence of multipath propagation. Firstly, by forming a differencing matrix from the array covariance matrix to eliminate the effects of uncorrelated incident signals and additive noises, a combined matrix is constructed from this differencing matrix to decorrelate the coherence of signals. Since the number of coherent signals is revealed as the rank of this resultant matrix, a singular value based ratio criterion is proposed to estimate the number of coherent signals. Then, another singular value based ratio criterion is also presented to determine the number of uncorrelated signals from the array covariance matrix. The notable advantage of the proposed method is that it can detect more signals compared to some existing methods, and the number of signals resolved by our method can exceed the number of array sensors.

关键词： Arrays Covariance matrix Signal to noise ratio Estimation Additive noise Narrowband Decorrelation

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