More and more industrial enterprises tend to validate their planning for new factories using simulation. Production environments often contain automated transport systems to move items between different work stations. We present a solution for modeling transport systems with respect to their interaction with all peripheries like robots and treatment machines. Modeling follows the process of mechanical assembly by putting together constructional components in 3-D space. Models of devices are of sufficient physical and electrical accuracy to test unmodified controller programs in a virtual commissioning phase to save time at the real start-up. In emulation, real controllers connect to the model to test and optimize control programs. In contrast to conventional discrete event simulation software, developers can play with the model during simulation to test its reaction and perform event of fault analysis. Simulation results are suited to secure design decisions of planners and reduce the risk of incorrect planning. Easy to recognize 3-D geometry and simulation interactivity qualify models for presentation and personnel training. Finally, simulation reveals suboptimal behavior and makes optimizations easier.

In the field of Computer Aided Manufacturing (CAM) solutions are required for the simulation of entire production environments including all hardware and software components inside an installation. In this regard, the so-called Digital Plant became more and more important. Several tools based on simulation techniques exist which support the developing of new production automation solutions and factories. In contrast to this, we introduce an innovative approach to realize the Digital Plant. Rest upon 3D graphical simulation we are able to process enlarged simulation models using distributed computing of the complex environment. The flexibility of the evolved interface between simulator's instances facilitates the coupling of other simulation tools to our system. Adapted from the identical interface we connect real controller systems to the partitions to simulate production control. The integration of the different software components extends the use of manufacturing simulation. In this article, we focus on distributing and simulating complex models to establish the base of the Digital Plant.

In 2004, the European COLUMBUS Module is to be attached to the International Space Station. On the way to the successful planning, deployment and operation of the module, computer generated and animated models are being used to optimize performance. Under contract of the German Space Agency DLR, it has become IRF's task to provide a Projective Virtual Reality System to provide a virtual world built after the planned layout of the COLUMBUS module enabling astronauts and scientists to practice operational procedures and the handling of experiments. The possibility for distributed multiuser access to the virtual lab and the visualization of real-world experiment data comprise the key features of the system. Through the ability to share the virtual world, cooperative operations can be practiced easily and trainers and trainees can work together more effectively in the shared virtual environment. The ability to visualize real-world data will be used to introduce measured experimental data into the virtual world online in order to allow realistic interaction with the science reference model hardware: The user's actions in the virtual world are translated into corresponding changes of the inputs of the science reference model hardware; the measured data is then in turn fed back into the virtual world. In order to provide astronauts and scientists with an even more complete insight into various aspects of COLUMBUS and the ISS, the simulation of the COLUMBUS module is currently being extended to include the entire International Space Station. This paper describes the background and the developed features which allow the creation of a virtual world that provides users with the feel of being on board the ISS.

This paper proposes the basic ideas of a proven dynamic collision avoidance approach for multirobot manipulator systems. The flexible use of multirobot systems requires new methodologies to ensure safe and collision-free movement of the controlled robots. The new method CARE (collision avoidance in real-time environments) that is presented in this paper is such a new safety methodology. Comparing this to existing approaches to collision avoidance, this new methodology has substantial advantages: (1) CARE makes sure, that the robots can generate the calculated evasive acceleration and avoid the collision at any time, (2) CARE is based on an intuitive, physically comprehensible and dynamic model of the collision process, which raises the confidence and the acceptance of such a safety system significantly, (3) CARE takes care of all potential collision dangers at the same time and, (4) CARE is model based so that it can be adapted to new robot kinematics or new robot work-cells only by modeling the new environment. All collision avoidance experiments with ERA have been carried out very successfully, whereby CARE has taken full control over the space robot.

Today's robot applications often include multi-robot multi-user environments which are planed thoroughly in 3D before installation. The key to gain the maximum benefit out of the already available models it is to reuse them for other purposes than only robot-simulation. One of these aspects surely is the training of future operators of the cell which is important especially for environments that are difficult to access for training. For example a production line in the automotive industry may not be shut down for a day of emergency-training. In this paper we will show how to reuse already modelled robot cells and mechanisms of the Cosimir simulation-system in emergency-training. We present an approach for graphical visualisation and simulation of fire. We show how to get realistic impressions of fire using advanced particle-simulation and how to use the advantages of particles to trigger states in a modified cellular automata used for the simulation of fire-behaviour. By this we can have a simulated fire developing and reacting on other fires and different substances as water, CO/sub 2/ or oxygen. It turns out that the mechanisms implemented for fire-simulation are also valuable for robot-simulation. So there is a mutual benefit between the robot-simulation and the simulation of fire. The methods proposed in this paper have been implemented and successfully tested on Cosimir, a commercial robot-and VR-simulation-system.

Building on existent robotics knowledge to model and simulate anthropomorphic kinematics is an appealing approach, because sound knowledge gained in the fields of multi-robot and multi-agent systems can be applied. This provides-with little additional effort-the "new human" with capabilities ranging from natural arm movement up to the coordinated operation of his arms and the cooperation between multiple anthropomorphic kinematics. The same general hierarchical control structure that has successfully been used to control multi-robot systems for space and industrial application has therefore been enhanced to incorporate the newly required capabilities. The enhancements focus on a new approach to on the one hand consider human extremities as articulated robots which are mechanically connected to make up the body-and on the other hand to provide a control strategy to move the full body correctly under equilibrium conditions. We provide an overall control structure that preserves the capabilities of the single robots and introduces "sensible couplings" to move the body as a whole in a naturally looking way. As described in the paper, this work is currently being applied to several application fields in industry up to the simulation of astronauts' work on the International Space Station.

Simulation techniques in the area of manufacturing automation have become more and more important. Thus, there are several tools available for planning and offline-programming of automated production processes. We describe an innovative universal simulation system, called COSMIR/sup /spl reg// Factory. Based on a unique approach to parallel simulation this tool extends the use of manufacturing simulations. On the one hand, the presented system facilitates the simulation of complex manufacturing processes. On the other hand, the once developed simulation model is suited for further applications like 3D process visualization, teleservice, and virtual training of operators. Beside the technical description of the system's architecture, we present a practical example comprising the simulation of a production line and the connection to a superimposed controller.

This paper presents a novel system that allows us to generate variants of industrial robot programs. Such a system is widely needed in different areas of application. First, product scenarios change often slightly and thereby cause high programming costs. Using our system reduces these costs, because nonspecialists can create a specific program variant by themselves. Second, an engineer needs numerous program variants to find an optimized cell layout, e.g. regarding robot execution time. Present systems require too much manual effort and are very limited in considering application-specific requirements. Consequently, we have implemented a system that contains an interpreter to execute user-defined scripts. A script contains the information on how to generate the program variants. Each change of the parameter values inside the script results in a different program. We simulate the program execution and use the simulation results to further improve the programs. We prove the usefulness of our system by industrial applications.

This paper introduces an object-based modeling method for automated manufacturing systems which particularly focuses on reusability and standardization. The models are built by selecting, configuring, and connecting elements from a building block library. An automatic translator generates fully functional and manually extendable PC-based work cell controllers from such models.

3D simulation and flexible control of robot-based workcells are in common use. However, many companies, especially SMEs, do not make use of the advantages these technologies imply. Reasons for this behavior are the costs of the software and hardware systems as well as the fact that one needs experts to operate those systems. This article describes an innovative architecture that has been developed for a corporate integration of simulation and control systems into production processes. The coexistence and cooperation of PC-based simulation and control makes the cost-effective use of virtual reality (VR) methods and a wide range of novel industrial applications possible. By use of VR technologies complex systems can be operated by any user without long periods of training. Thus, small- and middle-size companies are enabled to use innovative technologies to increase their productivity and competitiveness.

Presents an approach to facilitate the development and maintenance of translators for industrial robot programming languages. Such translators are widely used in robot simulation and offline programming systems to support programming in the respective native robot language. Our method is based upon a software architecture, that is provided as a complete translator framework. For the developer of a new translator, it offers convenient strategies to concentrate on robot specific language elements during the design and implementation process: fill-in templates, libraries for common functionality, design patterns etc., all tied up with a general translation scheme. In contrast to other compiler construction tools, the developers need not care about the complex details of a whole translator. As a matter of principle, the architecture offers a complete default translator (except for the grammar). Robot specific elements can be held in separate units-outside of the actual translator-to facilitate maintenance and feature extension. The most probable changes in the translator product life cycle are restricted to the adaptation of these units. Several translators built upon this framework are in actual use in the commercial robot simulation system COSIMIR(R) to support native language robot programming, as well as in the widely used robot programming system COSIROP to verify the syntax of robot programs.

The commanding and supervision of complex automation systems for space as well as for terrestrial automation applications is a demanding task. Modern developments in the field of virtual reality (VR) based man machine interfaces have the potential to facilitate such tasks enormously. At the Institute of Robotics Research (IRF) in Dortmund, Germany a variety of practical applications regarding the control of robots over long distances by means of virtual reality based man machine interfaces have been developed and successfully tested. In April 1999, the experiences made were successfully applied to the commanding and supervision of the robot ERA on board the Japanese satellite ETS-VII. In a joint mission between the Japanese Space Agency NASDA, the German Space Agency DLR and IRF, the robot was successfully commanded and supervised by means of "projective virtual reality" methods. The paper describes the key ideas and features of projective virtual reality as well as the metaphors used to augment the virtual world and to make the operation of the robot very intuitive. Before being able to apply the framework of projective virtual reality to this application, two major issues had to be addressed. First, it has to be made sure that the commanded robot can never damage itself or his environment this was addressed by automatic collision avoidance strategies. Secondly, the virtual model has to generated and then to be calibrated-this was addressed by the "TV-view into reality"-metaphor and modern 3D vision algorithms to provide the required online world-model updates.

The aim of the development of virtual reality (VR) for automation is to provide the framework for projective virtual reality which allows users to "project" their actions in the virtual world into the real world using robots and other means of automation. The framework is based on a task-oriented approach which builds on the "task deduction" capabilities of a VR system and a task planning component. Robots far from the control station can be controlled as easily as robots near it. This paves the way for a new quality of user-friendly man-machine interfaces for automation applications. This work has been enhanced by a new structure that allows to distribute the VR application over multiple computers. With this new step, it is now possible for multiple users to work together in the same virtual room, using only an Internet or ISDN connection. The distribution technology has been further developed to run the virtual world on many synchronized PC so that a panorama projection or even a cave can be run with 10 PC instead of high-end workstations, thus cutting down the costs for such a visualization environment drastically and allowing for a new range of applications.

This paper presents a new approach to the online planning of collision-free robot motions and evasive actions for redundant multi-robot/multi-obstacle environments. The approach, based on the collision avoidance methodology CARE (collision avoidance in real-time environments) presented by Rossmann (1993), is a local planning approach which considers the shortest distance and relative velocity between objects. This results in an intuitively comprehensible model to determine the potential collision and provides the basis of a new way of treating collision free path-planning as an optimization problem. This optimization problem is solved in real-time and provides a mathematically exact solution of the path-planning problem by considering all the static and dynamic obstacles in the environment.

This paper introduces the use of supervisory control techniques for the realization of a new kind of intuitive man machine interfaces for complex automation systems. Such comprehensive user interfaces combine for the first time intuitive commanding capabilities: clear and vivid visualization of the system state as well as interactive training environments especially for the commanding of autonomous robotic systems over long distances. To achieve this, a state oriented modeling technique has been developed. It serves as an object oriented supervisory control framework and was integrated in the IRFs VR-system COSIMIR/sup (R)/ VR.

Experiences in space robotics show, that the user normally has to cope with a huge amount of data. So, only robot and mission specialists are able to control the robot arm directly in teleoperation mode. By means of an intelligent robot control in cooperation with virtual reality methods, it is possible for non-robot specialists to generate tasks for a robot or an automation component intuitively. Furthermore, the intelligent robot control improves the safety of the entire system. The on-ground robot control and command station for the robot arm ERA onboard the satellite ETS-VII builds on a new resource-based action planning approach to manage robot manipulators and other automation components. In the case of ERA, the action planning system also takes care of the "real" robot onboard the satellite and the "virtual" robot in the simulation system. By means of the simulation system, the user can plan tasks ahead as well as analyze and visualize different strategies. The paper describes the mechanism of resource-based action planning, its application to different work cells, the practical experiences gained from the implementation for the on-ground robot control and command station for the robot arm ERA developed in the GETEX project as well as the services it provides to support VR-based man machine interfaces.

The new paradigm of projective virtual reality is presented as a sophisticated new approach to the control and supervision of robotic and automation systems. The idea behind projective virtual reality is to "project" actions that are carried out by users in the virtual world into the real world, primarily by means of robots but also by other means of automation. Robot control technology thus provides the user in the virtual reality with a "prolonged arm" into the physical environment, paving the way for a new quality of a user friendly man machine interface for automation applications. The paper provides the background of projective virtual reality which is based on latest results in the fields of task planning, world modeling, cooperative robot control and sensor-based robot control.

The problem of path control of automatically guided vehicles along a desired trajectory is considered where both lateral and longitudinal dynamics have been incorporated in the vehicle model. It is shown that a nonlinear decoupling controller and pole-placement can be used to obtain a closed-loop behavior that is independent of the vehicle operation point. For the pole-placement, the entire state is necessary. Since the sideslip is not available from measurements, an observer is applied, estimating the sideslip. Due to the steady state errors imposed by the nonlinear controller, a predictive filter is used to calculate this steady state error. The effectiveness of this controller is then demonstrated by simulations.

Practical experiences in the development of modern robot control systems showed that the most successful components developed were those that were designed to work in comprehensive automation systems. These components were forced to be implemented in a greater framework and thus to adhere to standards and to standardized interfaces in order to facilitate integration and test of the final system. Although it was suspected in the beginning that system constraints in the form of architectural design guides imposed on the different parts of the realization might hamper the creativity of the developers, it was found that just the opposite was the case. After a training phase the developers managed to "think globally, but act locally", so that e.g. the development, the integration and the tests of a multirobot system for space-applications, a robot-simulation system, a flexible assembly-workcell and a new virtual-reality-system could be conducted in a coherent manner in a very short time.

Industrial robots are increasing being applied in production situations of small quantity or single run units. These applications are characterized by a large product variety hence production flexibility is one of the most important requirements for new robot applications. In these applications, the robot must be seen as a single component of a flexible automation system, the robot-based flexible manufacturing work cell. Due to the numerous possible configurations in factories it is necessary to develop application specific modular manufacturing work cells by the usage of different components. Nevertheless it is the goal to standardize the work cell internal information structure, which permits the utilization of standardized control structures. The control components must be adaptable to different work cell configurations. In this paper the universal controller system LUCAS for robot-based flexible manufacturing work cells is described. For verification of the underlying control concepts some example applications in flexible assembly and flexible machining are shown. In addition, prospects for further developments are presented.>

The aim of the development of modern robot control systems at the Institute of Robotics Research is to provide higher flexibility and autonomy for robot systems, together with consistent and user-transparent concepts for installation, programming and operation of robots in their working environment. An important feature of a flexible future-oriented robot controller is the capability to incorporate information from different classes of sensors and to have standardized communication interfaces with other factory-automation components. To ease the robot systems' operation a graphical user-interface is provided. Furthermore, implicit programming and action planning methods allow robot programming on a much higher level of abstraction than today's procedural programming languages. For industrial applications, this implies easier and quicker adaptation of robot work cells to new tasks and a significant increase of the robots' flexibility to allow the feasibility of small quantity orders. This paper gives a basic description of "the principle of the hierarchical coordinator", the basic system concept for the development of complex control systems at the IRF. This concept has been developed and employed for the design of intelligent, autonomous robot systems, which are described in detail. The applications described range from the design of a flexible assembly work cell to a multirobot-system for autonomous experiment-servicing in a space laboratory module.>

In this paper a new approach to realistic simulation of robotic workcells in industrial manufacturing processes is presented, in which the workcell is composed of different classes of objects like robots, AGVs, conveyor-belts and sensors. The presented simulation system is directed to the areas of offline-programming and workcell layout. The novel approach described includes the embedding of an industrial robot controller into the simulation system by means of a versatile message-based interface and the use of a sophisticated environment model for intuitive simulation of grip and release operations, conveyor-belts and sensors. This is combined with a graphical 3D-visualization of the workcell in real-time and a windows-oriented interface based upon widely spread GUIs on PCs and UNIX-workstations.>

An approach to control of multiagent flexible manufacturing work cells is described. The concept is based on a strategic architectural model for hierarchical manufacturing control, which focuses on process sequence coordination in the bottom hierarchical layers. A work cell control system with universal applicability and free programmability is introduced. By utilization of user-defined device drivers the system can be adapted to different applications. The process sequence in the work cell depends on the individual product type and is described by process plans. A process planning system which supports user programming of the work cell controller is introduced.

A new and efficient method to stabilize an autonomously guided vehicle on desired trajectories under varying conditions is presented. Besides the task to improve safety in traffic, aspects of road behaviour and traveling comfort are especially considered. Since dynamical behaviour of a vehicle is highly nonlinear and contains mutual couplings in the state variables, design of the path control system is based on the universally valid principle of nonlinear decoupling and control. As this method works independent from operating points a high degree of accuracy and free pole assignment for the controlled vehicle is provided. Further a configuration is described, which causes damping of the yaw behaviour during high velocity cornering.

In the paper a general approach is given to the solution of the findpath problem in multi-robot systems based on a suitable structuring of the hierarchical overall system. The method developed uses a systematic design procedure for multi-robot systems which includes the design of the hierarchical coordinator for on-line collision avoidance. The efficiency of this new approach is demonstrated by several cases like the interaction of three stationary robots with different obstacles as well as by the interaction of mobile robots and moving obstacles.