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International Workshop on Hardware/Software Codesign (CODES)

作者： F. Fischer A. Muth G. Farber Laboratory for Process Control and Real Time Systems Technische Universität München Germany

Rapid Prototyping has been proposed as a means to reduce development time and costs of real-time systems. Our approach uses a heterogeneous, tightly coupled multiprocesser system based on off-the-shelf components as target architecture for an executable prototype, which is generated from the specification in an automated design process. Here, too, we aim to use existing tools and languages. But interface and communication synthesis, while being the key requirement of an automated translation of a abstract specification to a distributed system, is not yet state-of-the-art. The sensitivity of the overall performance of multiprocessor systems to overhead and latency introduced by communication on the other hand calls for an efficient interprocess communication (IPC). This paper presents concept and implementation of IPC functions which, implementing the message queue semantics of the specification language SDL, links the standard components of our multiprocessor system in an efficient manner while at the same time providing the interface synthesis needed by the automated generation of a rapid prototype. The experiences gained when implementing a non-trivial, real-world CAN controller and monitor application on our rapid prototyping environment, are described as a first proof of concept.

关键词： Prototypes Multiprocessing systems Costs real time systems process design Delay Specification languages control system synthesis Automatic control Monitoring

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Visual determination of 3D grasping points on unknown objects with a binocular camera system

Visual determination of 3D grasping points on unknown object...

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IEEE International Workshop on Intelligent Robots and systems (IROS)

作者： A. Hauck J. Ruttinger M. Sorg G. Farber Laboratory for Process Control and Real-Time Systems Technische Universität München Germany

In the field of hand-eye coordination, most state-of-the-art systems still require the user to select the grasping points manually. We present a system which autonomously determines 3D grasping points on unknown objects from a pair of greyscale images. The object to be grasped is segmented automatically when put into the scene. Grasping points are searched on the object silhouette; their stability is evaluated by a heuristic algorithm, primarily based on the skeleton of the region. The 3D grasping pose is estimated by triangulation using a simplified geometrical model of the camera system; the corresponding points in the second image are determined via dynamic programming. The whole system has been implemented and validated on the experimental hand-eye system MINERVA.

关键词： Cameras Solid modeling Image processing Dynamic programming Grippers Object detection process control real time systems Image segmentation Layout

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An MPEG-processor-based robot vision system for real-time detection of moving objects by a moving observer

An MPEG-processor-based robot vision system for real-time de...

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International Conference on Pattern Recognition

作者： N.O. Stoffler Z. Schnepf Lab. for Process Control & Real-Time Syst. Tech. Univ. Munchen Germany Laboratory for Process Control and Real-Time Systems Technische Universitat Munchen Munchen Germany

Describes a PC-based vision system that can be used to detect moving objects from a mobile robot. An image processing board equipped with an MPEG motion estimation processor calculates a sparse but robust optic flow in real-time. An algorithm to evaluate this kind of optic flow has been realized in software. It determines relevant motion parameters and a simple scene interpretation in terms of moving object regions. The image processing board and the algorithm are presented in some detail; the performance of the system is demonstrated by experiments.

关键词： Robot vision systems real time systems Image processing Image motion analysis Machine vision Object detection Mobile robots Motion estimation Robustness Software algorithms

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An image processing board with an MPEG processor and additional confidence calculation for fast and robust optic flow generation in real environments

An image processing board with an MPEG processor and additio...

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International Conference on Advanced Robotics (ICAR)

作者： N.O. Stoffler G. Farber Laboratory for Process Control and Real-Time Systems Technische Universität München Munchen Germany

This paper describes a vision system based on a PC-board which can calculate a sparse but robust optic flow at frame rate. A correlation chip, which was originally designed for MPEG video compression, is used to calculate displacement vectors between blocks of pixels in consecutive frames. The main disadvantage of similar approaches, the noisiness of the displacement field in areas with weak structure, is compensated by a computational inexpensive confidence criterion, which is calculated for each vector in hardware. The performance of the criterion and the improvements in the flow field are demonstrated by experiments.

关键词： Image processing Image motion analysis Transform coding Optical noise Robot vision systems Video compression Cameras Lighting Noise generators Robustness

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NoWait-RPC: extending ONC RPC to a fully compatible message passing system

NoWait-RPC: extending ONC RPC to a fully compatible message ...

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International Symposium on Parallel processing

作者： T. Hopfner F. Fischer G. Farber Laboratory for Process Control and Real-Time Systems Germany Technische Universität München Germany

Locally and functionally distributed applications realized on different system architectures demand a universal, portable and intuitive software utility for interprocess communication. Remote Procedure Calling (RPC) fulfills these requirements but suffers unnecessarily strict synchronization and the danger of deadlocks with complex client/server relations. Using message passing to avoid the inherent problems of RPC, however requires additional knowledge and sometimes a complete structural redesign. This paper presents NoWait-RPC, an extended but fully compatible version of SUN's Open Network Computing Group's ONC RPC, which adds message passing capabilities to form an easy to use programming environment for robust system integration. NoWait-RPC was developed to resolve potentially arising deadlocks in an already RPC-based complex application. It is designed to be a plug-and-play substitute for ONC RPC and consists of the library and the extended protocol compiler nwrpcgen. Additionally, applications using the asynchronous (non-blocking) features of NoWait-RPC may experience a major speedup compared to ONC RPC through pipelining calls to different servers. It has successfully been employed in a research programme dealing with the development of autonomous mobile robots.

关键词： Message passing System recovery Application software Computer architecture Communication system software Network servers Sun Computer networks Programming environments Robustness

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Improving processor utilization with a task classification model based application specific hard real-time architecture

Improving processor utilization with a task classification m...

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IEEE International Conference on Embedded and real-time Computing systems and Applications (RTCSA)

作者： G. Farber F. Fischer T. Kolloch A. Muth Laboratory for Process Control and Real-Time Systems Technische Universität München Munchen Germany

Modern microprocessors with caches and pipelines show increasing performance, but at the price of a decreasing predictability of execution times. The design of hard real time systems however has to be based on worst case considerations. Consequently, real-time systems are generally oversized and fail to profit of developments in the standard processor field. This paper presents an approach where real-time systems are analyzed and built according to a task classification model. Each class of tasks corresponds to a type of processor best suited in terms of performance and deterministic execution times. The resulting target architecture framework is a tightly coupled heterogeneous multiprocessor system based on templates using off-the-shelf components. The described real-time system design process includes a schedulability analysis method that supports the partitioning and allocation process and provides the necessary real-time guarantees. The result is a event-driven hard real-time system with improved processor utilization that will provably meet all its deadlines. A rapid prototyping platform implementing this concept is presented as well as application examples.

关键词： real time systems Microprocessors Random access memory System analysis and design processor scheduling Prototypes Delay Laboratories process control Modems

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Active controlled exploration of 3D environmental models based on a binocular stereo system

Active controlled exploration of 3D environmental models bas...

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International Conference on Advanced Robotics (ICAR)

作者： D. Burschka G. Farber Laboratory for Process Control and Real-Time Systems Technische Universität München Munchen Germany

This paper describes the exploration of indoor environments based on a binocular stereo system mounted on a mobile vehicle. It introduces the algorithms for the control of the vehicle and the camera mount depending on the explored and the a priori known information about the environment. The controlled vehicle does not follow a precompiled path but finds its goals depending on the perceived information. The resulting environmental model is stored in a multilayer map storing the three-dimensional boundary lines of the objects at their geometrical positions in the world. The line description in the model is adapted to meet the requirements of a successive exploration with a video camera.

关键词： Sensor systems Cameras Navigation Vehicle dynamics process control real time systems World Wide Web Solid modeling Nonhomogeneous media Path planning

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Flexible real-time Algorithms Adapting Themselves to Alternating Load Situations

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IFAC Proceedings Volumes 1997年第4期30卷 51-56页

作者： Johann Pfefferl Georg Färber Laboratory for Process Control and Real Time Systems Prof. Dr.-Ing. G. Färber Technische Universität München Germany

In many applications, approximate results are often sufficient to achieve an acceptable behavior of a real–time system. Imprecise calculations could be necessary due to a transient overload situation caused by extraordinary events. To handle this exceptional work as well as the normal tasks, it is possible to reduce temporarily the computation time of the normal jobs by applying a more intelligent and flexible form of algorithms. In this paper, algorithm structures are presented, which are suitable to implement the mentioned methods. The basic idea is to offer multiple algorithm alternatives of different complexities for solving a problem. Then one can decide with the knowledge of the deadline and of the computation time which of the alternatives can be executed in time. These decisions will happen at runtime. To prove the applicability of the proposed methods on a real system, the theoretical considerations are devolved to a practical example consisting of a vehicle convoy. In this system, a normally realized control unit is substituted by an imprecisely working one. The effects of this action are described and analyzed with regard to the normal implementation. Therefore, a number of simulation results are presented. There exists also an experimental setup for verification in a real environment.

关键词： real–time algorithms load adaptation imprecise computation techniques and resulting errors control systems

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A biologically motivated model for the control of visually guided reach-to-grasp movements

A biologically motivated model for the control of visually g...

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IEEE International Symposium on Intelligent control (ISIC)

作者： A. Hauck M. Sorg G. Farber T. Schenk Laboratory for Process Control and Real-Time Systems Technische Universitat Munchen Germany Department of Neurology Ludwig-Maximilians Universitat Munchen Germany

Human grasping still outshines its robotical counterparts with respect to accuracy, speed, robustness, and flexibility. When trying to develop a robotical hand-eye system, it therefore suggests itself to examine the results of neuroscience. In this paper, we describe a model for visually guided reach-to-grasp movements that unifies the two robotical strategies look-then-move and visual servoing, thereby compensating the problems that each strategy shows when used alone. This model was developed by analyzing and extending current models for the control of human reach-to-grasp movements.

关键词： Biological system modeling Biological control systems Humans Robot sensing systems Robot kinematics Robot control Service robots Manipulators Motion control control systems

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The Arbitrated Networked control systems Approach to Designing Cyber-Physical systems *

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IFAC Proceedings Volumes 2012年第26期45卷 174-179页

作者： Anuradha Annaswamy Samarjit Chakraborty Damoon Soudbakhsh Dip Goswami Harald Voit Active-adaptive Control Laboratory MIT Cambridge MA USA Institute for Real-time Systems TU Munich Germany

The domain of networked control systems (NCS) has traditionally been concerned with modeling and designing distributed controllers in the presence of control message loss, varying delay and jitter. Here, the characteristics of the network are assumed to be given and the focus has largely been on the controller. While this is meaningful in the context of control over wireless networks, where the network is assumed to be predesigned, in many other domains there is considerable flexibility in designing the network itself. For example, in an automotive architecture, distributed controllers are implemented on multiple electronic control units (ECUs) that communicate over CAN or FlexRay buses. The network design problem in this case consists of mapping control tasks to ECUs, and determining both the scheduling parameters for the ECUs as well as those for the communication buses. Given a choice of these parameters, the controller design problem is similar to that studied in NCS, i.e., that of designing/analyzing the controller. However, the joint design and optimization of the network and the controller gives rise to new research questions, that have neither been studied within the NCS, nor within the embedded systems domain. We refer to such systems as arbitrated networked control systems (ANCS) to emphasize the fact that the arbitration policy in the network also needs to be determined, and discuss recent results that have been obtained in the literature in this context.

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