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arXiv 2018年

作者： Tatarenko, Tatiana Kamgarpour, Maryam Department of Control Theory and Robotics Tu Darmstadt Automatic Control Laboratory Eth Zürich

We consider online convex optimization with a zero-order oracle feedback. In particular, the decision maker does not know the explicit representation of the time-varying cost functions, or their gradients. At each time step, she observes the value of the cost function evaluated at her chosen action (zero-order oracle). The objective is to minimize the regret, that is, the difference between the sum of the costs she accumulates and that of the static optimal action had she known the sequence of cost functions a priori. We present a novel algorithm to minimize the regret in both unconstrained and constrained action spaces. Our algorithm hinges on a classical idea of one-point estimation of the gradients of the cost functions based on their observed values. However, our choice of the randomization introduced and consequently the proof techniques differ from those of past work. Letting T denote the number of queries of the zero-order oracle and n the problem dimension, the regret rate achieved is O(nT2/3) for both constrained and unconstrained action spaces. Moreover, we adapt the presented algorithm to the setting with two-point feedback and demonstrate that the adapted procedure achieves the theoretical lower bound on the regret of Θ(n√T). Copyright © 2018, The Authors. All rights reserved.

关键词： Cost functions

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Requirements for robot assisted disassembly of not appropriately designed electronic products: lessons from first studies

Requirements for robot assisted disassembly of not appropria...

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IEEE International Symposium on Electronics and the Environment

作者： A. Weigl Control Systems Theory and Robotics Department Darmstadt University of Technology Darmstadt Germany

For environmental and economical reasons future applications in automation may focus on robot assisted disassembly of a large variety of electronic products with the general aim to re-use valuable modules, sub-assemblies and components recovered from old products. This paper presents first activities, investigations and experiments in applying intelligent robots to autonomous disassembly of electronic products. In particular the structure of a flexible robot system, including suitable actuators and sensors is developed and disassembly difficulties which arose in the first experiments are analysed. As a representative example for electronic products a video camera recorder has been selected for practical disassembly experiments. The robot system used within this research work comprises a six-axes robot arm a three-fingered dexterous gripper, a two-jaw-gripper, a wrist force/torque-sensor and a multicamera imaging system.< >

关键词： robotics and automation Robot sensing systems Environmental economics Intelligent robots Actuators Intelligent sensors Sensor systems Robot vision systems Cameras Grippers

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Discrimination properties of invariants using the line moments of vectorized contours

Discrimination properties of invariants using the line momen...

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International Conference on Pattern Recognition

作者： G. Lambert J. Noll Control System Theory and Robotics Department Darmstadt University of Technology Darmstadt Germany

In this paper a new approach for image analysis in real time based on the vectorized contours of a scene is presented. Taking advantage of the fast and efficient determination of the line moments, invariants with respect to translation, scaling and rotation are derived. Four different sets of rotational invariants are introduced and their performance is examined on two examples. Moreover, a quality measure for class discrimination of feature sets is presented and investigated. Using this quality measure as a cost function, heuristic search strategies and genetic algorithms are employed for the feature selection. Thus, high dimensional feature spaces are reduced significantly without losing relevant image information. The performance of both the full and the reduced data sets is investigated on a set of noisy patterns and on a set of letters.

关键词： Layout Image edge detection Data mining Integral equations Hardware Image segmentation control systems Robots Image analysis Cost function

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A modular approach for solving the peg-in-hole problem with a multifingered gripper

A modular approach for solving the peg-in-hole problem with ...

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IEEE International Conference on robotics and Automation (ICRA)

作者： K. Kleinmann D.M. Bettenhausen M. Seitz Department of Control Systems Theory and Robotics Darmstadt University of Technology Darmstadt Germany

This paper discusses the peg-in-hole task performed by a system integrating a dextrous hand, a 6-DOF robot and a camera. It is shown how the starting conditions of the final insertion only performed by the fingers are affected by the previous stages. Based on the experimental findings, some criteria for the overall system design and the required manipulation capabilities of the gripper are derived. With respect to this performance evaluation a modular concept for solving insertion tasks with a multifingered gripper is presented. The object manipulation is realized by primitives which are executed in dependence on various assembly states. The implementation of this approach is described and beside a theoretical characterization, experimental results are given.

关键词： Grippers Fingers control systems Employment Robot sensing systems Automatic control robotics and automation Assembly Force measurement Robot vision systems

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Mobile robot localization using a selforganized visual environment representation

Mobile robot localization using a selforganized visual envir...

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Euromicro Workshop on Advanced Mobile Robot

作者： G. von Wichert Control Systems Theory & Robotics Department Darmstadt University of Technology Darmstadt Germany

Due to the upcoming applications in the field of service robotics mobile robots are currently receiving increasing attention in industry and the scientific community. Applications in the area of service robotics demand a high degree of system autonomy, which robots without learning capabilities will not be able to meet. Learning is required in the context of action models and appropriate perception procedures. Both are extremely difficult to acquire especially with high bandwidth sensors (e.g. video cameras) which are needed in the envisioned unstructured worlds. Self-localization is a basic requirement on mobile robots. This paper therefore proposes a new methodology for image based self-localization using a self-organized visual representation of the environment. It allows for the seamless integration of active and passive localization.

关键词： Mobile robots Layout Feature extraction Image segmentation Cameras Robustness Quantization Pixel Robot vision systems Orbital robotics

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Experimental Validation of a Self-Adjusting Active Compliance controller for Multiple Robots Handling an Object

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IFAC Proceedings Volumes 1998年第33期31卷 59-64页

作者： Christian von Albrichsfeld Henning Tolle Darmstadt University of Technology Institute of Control Engineering Department of Control Systems Theory & Robotics Landgraf-Georg-Strasse 4 D-64283 Darmstadt

This paper presents the experimental validation of a self-adjusting active compliance controller for n robots handling a concerning its compliant behaviour partly unknown flexible object. The control strategy is based on the decomposition of the 6n-dimensional position/force space and includes a feedforward and feedback level. For adjusting the controller to the in general unknown flexible behaviour, which is the main problem of the controller design. a quasi-static model of the system is derived for different contact cases of the object and a procedure is presented, which by use of this model is capable of determining the compliance of the considered system and therefore of adjusting the controller. Experiments with two pumatype robots show the applicability of the self-adjusting control strategy.

关键词： self-tuning control force-position control admittance control compliance control decoupling problems multi-arm robots intelligent control robot control

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Object manipulation by a multifingered gripper: on the transition from precision to power grasp

Object manipulation by a multifingered gripper: on the trans...

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IEEE International Conference on robotics and Automation (ICRA)

作者： K.P. Kleinmann J.-O. Hennig C. Ruhm H. Tolle Department of Control Systems Theory and Robotics Darmstadt University of Technology Darmstadt Germany

Whereas the emphasis of precision grasping only using the fingertips is placed on dexterity and sensitivity, power grasps guarantee high security and stability. But even if the task requires a power grasp, in the initial configuration the complete enveloping by the fingers is often impossible due to the position of the object in the workspace and only a fingertip grasp can be applied. Then a transition from precision to power grasping has to be performed. Based on an experimental study this paper discusses several possibilities to realize this transition by using a three-fingered dextrous hand mounted on a 6DOF robot. In particular it is distinguished between strategies requiring a coordination of robot and hand and strategies performing the transition only by the fingers like humans do.

关键词： Grippers Humans Fingers Grasping Medical robotics Robust stability control systems Robot sensing systems Power system security Humanoid robots

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Automatic transformation of simple user commands to hierarchical Petri nets

Automatic transformation of simple user commands to hierarch...

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IEEE International Conference on Systems, Man and Cybernetics

作者： B. Strege H. Tolle H. Loydl Control Systems Theory and Robotics Department Technical University of Darmstadt Darmstadt Germany

Petri nets represent a highly effective tool for the development of control systems for flexible manufacturing cells (FMC) due to their graphical modeling technique, compact representation, the availability of mathematical analysis tools and the direct transformability to PLC (programmable logic controller) programs. Since FMC control systems are required to be modifiable by low-qualified operators on the shop floor and Petri nets are too complex for them, this paper describes a concept to overcome this problem; it is based on strategic commands and information about the manufacturing system which can be specified in object-oriented following the morphological concepts commonly used by the operators and are then automatically transformed to Petri nets. An example shows how the methodology works in practice.

关键词： Petri nets Programmable control control system synthesis Automatic control Flexible manufacturing systems Virtual manufacturing Object oriented modeling Mathematical model Availability Mathematical analysis

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On interpolation memories for learning control

On interpolation memories for learning control

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IEE Colloquium on Advances in Neural Networks for control and Systems

作者： H. Tolle Institute of Control Engineering Department of Control systems Theory and Robotics Technical University of Darmstadt Darmstadt Germany

The paper deals with new developments of interpolating memories as the basic element of learning control and with their possible application. It discusses learning control, interpolating memories, characteristic manif... 详细信息

关键词： Interpolation Learning systems

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A self-organizing associative memory system for control applications 89

A self-organizing associative memory system for control appl...

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Proceedings of the 3rd International Conference on Neural Information Processing Systems

作者： Michael Hormel Department of Control Theory and Robotics Technical University of Darmstadt Darmstadt W.-Germany

The CMAC storage scheme has been used as a basis for a software implementation of an associative memory system AMS, which itself is a major part of the learning control loop LERNAS. A major disadvantage of this CMAC-concept is that the degree of local generalization (area of interpolation) is fixed. This paper deals with an algorithm for self-organizing variable generalization for the AKS, based on ideas of T. Kohonen.

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