Jürgen Rossmann

The “DLR crash report”: Towards a standard crash-testing protocol for robot safety - Part II: Discussions

After giving a rich data basis of our impact tests with standardized crash-test dummies in Part I of this work we address in Part II various aspects related to these tests in a case based discussion. The presented facts, the knowledge gained from our previous work, and the data from Part I lead us to recommendations for standardized crash-testing procedures in robotics. The proposed impact procedures will help to compare blunt robot-human impacts on a common basis. We will discuss additional requirements which will enhance the completeness of testing procedures.

Real-time reactive motion generation based on variable attractor dynamics and shaped velocities

This paper describes a novel method for motion generation and reactive collision avoidance. The algorithm performs arbitrary desired velocity profiles in absence of external disturbances and reacts if virtual or physical contact is made in a unified fashion with a clear physically interpretable behavior. The method uses physical analogies for defining attractor dynamics in order to generate smooth paths even in presence of virtual and physical objects. The proposed algorithm can, due to its low complexity, run in the inner most control loop of the robot, which is absolutely crucial for safe Human Robot Interaction. The method is thought as the locally reactive real-time motion generator connecting control, collision detection and reaction, and global path planning.

Systems approach to robotics and automation

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.

Dynamic collision avoidance for redundant multi-robot systems

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.

State oriented modeling as enabling technology for projective virtual reality

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.

Application of automatic action planning for several work cells to the German ETS-VII space robotics experiments

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.

Intelligent autonomous robots for industrial and Space applications

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 todays 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.<<ETX>>

Multimedia and virtual reality techniques for the control of ERA, the first free flying robot in space

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.

Controlling anthropomorphic kinematics as multi-agent systems

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.

Fire-training in a virtual-reality environment

Although fire is very common in our daily environment - as a source of energy at home or as a tool in industry - most people cannot estimate the danger of a conflagration. Therefore it is important to train people in combating fire. Beneath training with propane simulators or real fires and real extinguishers, fire training can be performed in virtual reality, which means a pollution-free and fast way of training. In this paper we describe how to enhance a virtual-reality environment with a real-time fire simulation and visualisation in order to establish a realistic emergency-training system. The presented approach supports extinguishing of the virtual fire including recordable performance data as needed in teletraining environments. We will 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. Using particle systems that interact with cellular automata it is possible to simulate a developing, spreading fire and its reaction on different extinguishing agents like water, CO2 or oxygen. The methods proposed in this paper have been implemented and successfully tested on Cosimir, a commercial robot-and VR-simulation-system.