The purpose of this paper is to give an overview of past and recent work on planning sensing strategies for vision sensors. To achieve an economic use of robots in manufacturing, their programs must provide a high deg...
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The purpose of this paper is to give an overview of past and recent work on planning sensing strategies for vision sensors. To achieve an economic use of robots in manufacturing, their programs must provide a high degree of fault-tolerance, security, and robustness to prevent unforeseen errors. Model errors (also termed uncertainties) are one of the most frequent reasons for such undesirable events. Robot systems can be made more reliable and fault-tolerant by providing them with capabilities of error detection and recovery, or error prevention. The latter may be achieved by reducing model errors using tactile and non-tactile sensors. The quality of a robot program synthesized by a task-level programming system depends on the accuracy of the model, since all information that is not explicitly given by the programmer must be derived from it. This means that the following questions have to be answered by the automatic task planner in order to plan non-tactile sensing strategies: (1. When do I have to use sensors to reduce uncertainty about the {1. world? (2) What do I have to use them for? (3) How do I have to use them to achieve the necessary information within an acceptable period of time? There are very few systems which deal broadly with the problem of robust robot programs, whereas there are numerous works on detail aspects of the field. The main approaches will be introduced and discussed in more detail. Finally, a new concept for generating sensor-integrated robust robot programs will be proposed.
In this article, the development of an action-based process model is described which was especially tailored to the needs of modelling and simulating multifinger hands. The research has been concerned with a descripti...
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In this article, the development of an action-based process model is described which was especially tailored to the needs of modelling and simulating multifinger hands. The research has been concerned with a description technique using constraints for modelling the working environment and with the design of an appropriate process model for simulating complex movements of manipulation objects with multifinger hands. The paper presents the results of an object-oriented approach to the proposed model and consists of two parts: a constraint net that describes the connections and relations between cell components (robots, grippers, objects) in the working environment and a propagation algorithm that computes the new locations regarding the modifications and logical dependencies.
This contribution presents results of a research project concerned with the planning and execution of motions in uncertain environments. In particular, the problem of a moving convex polygon within an uncertain two-di...
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This contribution presents results of a research project concerned with the planning and execution of motions in uncertain environments. In particular, the problem of a moving convex polygon within an uncertain two-dimensional environment has been investigated. The essential sub-problem of how to analyse unexpected contacts is treated. Using a set-oriented model of the uncertainties, the motion possibilities of the polygon is investigated for the different contact types. Also based on the model of the uncertainties, the potential locations of the geometric elements are constructed and intersected, giving us the contact hypotheses. With the help of exploratory motions, an attempt is made to decide between ambiguous hypotheses. The question of which exploratory motions are useful for the different contact types is also investigated. After an exploratory motion has been executed, its results must be evaluated with respect to the validity of the hypotheses. The system has been implemented and is also described in this paper.
Robots have been a subject of research for almost half a century. In order to make robots more versatile they must be able to operate in a semi-structured work place where unforeseen events occur and where sensor data...
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Robots have been a subject of research for almost half a century. In order to make robots more versatile they must be able to operate in a semi-structured work place where unforeseen events occur and where sensor data are incomplete. An entire research community has been working on this problem and many unique autonomous and so-called intelligent robots have been conceived and built. Most of these efforts are concerned with robots that operate in the macroworld where they take on chores that could also be handled by humans. However, there is the macroworld in which manipulation and handling tasks are very difficult and for which a human has no tools and where the work area is so small that fine manual manipulation is almost impossible. This paper is concerned with autonomous robots that can operate in a microworld, where microassembly operations, microsurgery or integrated circuit testing and repair is done. For independent operations, these robots need special sensors and an efficient computer architecture that hosts the planner and executor. There are also special drive {1. and effecters necessary for micromotions and micromanipulations, respectively. An attempt is made to describe these components and the problems encountered in configuring them to a microrobot. As an example of advanced microrobots, the design and functions of several autonomous microrobots of the University of Karlsruhe are shown;they employ different locomotion and subject handling principles. The paper also includes a discussion of the typical operating problems caused by the microworld and of future research that has to be done to conceive and build efficient microrobots.
A mobile robot that navigates in an unknown or changing environment needs to maintain a dynamic model of its environment in order to update existing knowledge about the world. This paper addresses the problem of how t...
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A mobile robot that navigates in an unknown or changing environment needs to maintain a dynamic model of its environment in order to update existing knowledge about the world. This paper addresses the problem of how to update a local model of the perceivable environment of a mobile robot and how to produce a description of newly perceived obstacles. A new hybrid concept is presented which combines the advantages of parameter- and grid-based modelling techniques. By introducing local grids that only cover areas where new obstacles are expected, the complexity of the map building process is significantly reduced. Local grids can be used in dynamic environment which was not possible with earlier grid-modelling approaches. The information, grids are constructed from, is provided by ultrasonic range sensors and an active stereo-vision system, Fusing information of both sensor systems is advantageous, especially due to their complementary error characteristics concerning range and angular resolution.
A new product model that is particularly useful for model-based assembly planning is presented in this paper. The majority of the models used in this domain are simple approximations of the real workpiece and they are...
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A new product model that is particularly useful for model-based assembly planning is presented in this paper. The majority of the models used in this domain are simple approximations of the real workpiece and they are often dedicated to special algorithms. The model described here provides a more accurate and more flexible representation of workpieces. An increase in accuracy of the shape description was achieved by enhancing a polyhedral model with an analytical representation. The application of the model is demonstrated within the framework of assembly sequence planning.
This text presents an approach for planning robot workcells in three dimensions fully automatically. This automation is possible by a complete layout planning process inside the configuration space. To reach a suffici...
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This text presents an approach for planning robot workcells in three dimensions fully automatically. This automation is possible by a complete layout planning process inside the configuration space. To reach a sufficient shop floor layout in a short time, the cartesian configuration space and fast obstacle transformation routines are employed. An optimization algorithm minimizes the length of all collision free paths required for the performance of the workcell task. A final check by a graphical workcell task simulation, whether the layout is valid or not, is no longer required. This new planning approach enhances the conventional layout planning process and reduces the amount of necessary user interaction.
An approach for applying a structural texture analysis method to automatic visual inspection of fabric samples in the textile industry is presented. The main steps (image preprocessing, image segmentation, model descr...
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In this paper the control architecture of the mobile robot system PRIAMOS is presented. It consists of four layers which integrate reactive and reflexive components in such a way that the robot can combine fast reacti...
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In this paper the control architecture of the mobile robot system PRIAMOS is presented. It consists of four layers which integrate reactive and reflexive components in such a way that the robot can combine fast reaction to unexpected obstacles with predictive behaviour to known components in the environnement. A solution for the problem bow to combine control layers which process information on different levels of abstraction and of increasing complexity is discussed. The reflexive part of the control architecture and the modification concerning the motion controller of the mobile robot which was necessary to apply the idea of reflexive navigation is described in more details. The architecture presented allows to execute motion tasks in partially unknown or changing environment in an efficient manner. Especially the time critical reflexive level is computationally less expensive than previous approaches
The focus of this paper is to address a novel control technique for stability and transparency analysis of bilateral telerobotic systems in the presence of data loss and {1. delay in the communication channel. Differ...
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The focus of this paper is to address a novel control technique for stability and transparency analysis of bilateral telerobotic systems in the presence of data loss and {1. delay in the communication channel. Different control strategies have been reported to compensate the effects of {1. delay in the communication channel;however, most of them result in poor performance under data loss. First, a model for data loss is proposed using a finite series representation of a set of periodic continuous *** improve the performance and data reconstruction, a holder circuits is also introduced. The passivity of the overall system is provided via the wave variable technique based on the proposed model for the data loss. The stability analysis of the system is then derived using the Lyapunov theorem under the {1. delay and the data loss. Finally, experimental results are given to illustrate the capability of the proposed control technique.
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