Juergen Rossmann

Control by 3d simulation --- a new erobotics approach to control design in automation

This paper introduces new so-called control by 3D simulation concepts which are the basis for the simulation based development of complex control algorithms e. g. in the field of robotics and automation. Now, a controller design can be developed, parameterized, tested and verified using so called Virtual Testbeds until they perform adequately in simulation. Then a stripped down version of the same simulation system uses the same simulation model and the same simulation algorithms on the real hardware implementing a real-time capable controller. This results in an integrated development approach, which brings simulation technology on the real hardware to bridge the gap between simulation and real world operation. In this way, Virtual Testbeds and control by 3D simulation provide major building blocks in the emerging field of eRobotics to keep manageable the ever increasing complexity of current computer-aided solutions.

Developing Virtual Testbeds for mobile robotic applications in the woods and on the moon

Simulation in the context of engineering often focuses on very special details of global systems. Robot designers usually begin with the analysis of new actuators and joint designs. This corresponds to a “bottom-up”-strategy in the development of simulation models. For classical fields of application of robotics, e.g. in production plants with a well defined environment this is the approved method, because it allows very detailed insights into the analyzed subsystems. On the other hand, unpredictable effects of the interaction of multiple subsystems may easily be overseen. In particular, nontechnical environments like in moon exploration tasks or in a biological environment like in forestry applications are hard to describe in an analytical way to integrate them into an analytical simulation model. This is why this paper presents the idea and some practical aspects of the development of “Virtual Testbeds”. In a Virtual Testbed, the entire system is simulated as a whole in Virtual Reality - not only small subsystems of a global system. According to the requirements different subsystems are simulated with different levels of detail. In contrast to the classical “bottom-up”-strategy this can be seen as a “top-down”-approach. Therefore the employment of a multi-body dynamics system as a platform for the development of versatile simulation and testing environments is proposed. Using the examples of the evaluation and testing of an extraterrestrial walking exploration robot design and the development of a method for self-localization in forestry, the idea is further deepened. As a special field of attention the integration of a method of soil simulation as a particular requirement of a Virtual Testbed for walking exploration robots is presented.

Support vector machine based decision tree for very high resolution multispectral forest mapping

The goal of this study is the discrimination of seven tree species. As a well known approach the k-nearest neighbor classifier is compared to a support vector machine based decision tree. This classifier uses advanced support vector machines to implement a hierarchical classification scheme by combining it with decision tree induction. At each node of the decision tree a support vector machine is trained. Furthermore the impact of LIDAR differential data and kernel choice is evaluated. The effects of two separability measures and three grouping strategies in the decision tree induction on the classification results of the support vector machine based decision tree (SVMDT) are studied.

Advanced Sensor Simulation In Virtual Testbeds: A Cost-Efficient Way to Develop and Verify Space Applications

Developing and testing components for space applications is a cost-intensive and timecritical process. Therefore, prospective missions and projects in space business will mostly be carried out in international cooperation, e.g. between the American space agency NASA and the German space agency DLR. A major challenge is the distributed development of components, implementation of algorithms and testing, as expensive hardware cannot be provided at each research facility. To resolve this situation, so called ’Virtual Testbeds’ (VT) are currently being developed. VTs provide a comprehensive and integrated simulation of the components as well as of the entire target systems and thus allow to perform a major part of the required testing without the physical hardware. In this paper we present the ’Virtual Testbed’ concept, which is able to virtualize complete mission scenarios. A focus is laid on the highly realistic sensor simulation, as they are a very important part in many virtual testbed applications supporting the envisaged iterative development and validation process. The implemented sensor simulation framework is accurate, versatile and exible enough to help to eliminate systematical errors not only during the virtual prototyping phase. Developers also use it for control code debugging, subsystem- and system validation in the implementation and test phases. This results in shorter development times, while simultaneously decreasing the developing costs dramatically.

Virtual reality technologies for the realistic simulation of excavators and construction machines: from VR-training simulators to telepresence systems

At the Institute of Robotics Research in Germany (IRF), an excavator- and construction machine simulator based on latest virtual reality technology has been developed. The main issues of the realization so far have been the real-time capability, the close-to-reality presentation of the environment and the physically correct simulation of the process, i.e. the simulation of the flow of the material handled with e.g. the simulated excavator. In the next step, it is being envisaged to enhance the system in a way that it cannot only be used for training, but also to command and supervise large construction machines in real world applications by means of virtual reality and automatic action planning components. Experiences gained from the control of space robots being controlled by methods of “projective virtual reality” will be introduced into this application to allow one driver to remotely control several excavators e.g. in a mining environment. In the paper, we describe how the simulation of the excavator and its interaction with the handled material can be handled mathematically and we will explain the basic ideas of how to “project” action that were carried in the virtual word onto physical excavators by employing the methods of projective virtual reality.

Close to Reality Simulation of Bulk Solids Using a Kind of 3D Cellular Automaton

The development of algorithms providing a close to reality simulation of dynamic virtual worlds made substantial technological progresses during the last decade — contrary to the close to reality simulation of bulk solids. Standard simulation methods like particle or rigid-body simulation are not applicable to this simulation problem because a large number of elements is needed for convincing simulation results which cannot be handled in real-time. In this paper we present a kind of 3-dimensional cellular automaton which can handle a large number of elements at the cost of a spatial discretization. This approach is combined with state of the art rigid body simulation techniques resulting in a close to reality simulation of bulk solids in real-time applications.Copyright

A Virtual Testbed for Human-Robot Interaction

Many research efforts in human-robot interaction (HRI) have so far focussed on the mechanical design of intrinsically safe robots, as well as impedance control for tasks in which human and robot will work together. However, comparatively little attention is paid to an approach that ensures safety and permits close HRI while dispensing human with the necessity of physical presence in close proximity to the robot. In this work we acquire real human manipulation gestures using Microsofts Kinect sensor and project them in realtime into the workspace of a simulated, impedance controlled robot manipulator. This way, we can remotely and therefore safely superimpose human motion over the robots dynamic motion, wherever the human operator is located. The simulated robot state is then transferred to the real robot as input, so as to physically perform the intended task. The Virtual Testbed approach might not only be useful for HRI pre-analysis, testing and validation goals but particularly advantageous for telepresence, industrial and harzardous tasks as well as training purposes. Simulation results are provided to show the effectiveness of the approach.

A comparison of different metaheuristic algorithms for optimizing blended PTP movements for industrial robots

The optimization of robot paths is important to reduce cycle times in industrial production processes. Even small time savings will accumulate and thus reduce production costs. This paper shows a method to automate the optimization of blended PTP movements for industrial robots and compares the performance of three metaheuristics.

Projective virtual reality in space applications: a telerobotic ground station for a space mission

Commanding complex robotic systems over long distances in an intuitive manner requires new techniques of man-machine- interaction. A first disadvantage of conventional approaches is that the user has to be a robotic expert because he directly has to command the robots. He often is part of the real-time control loop while moving the robot and thus has to cope with long delays. Experience with space robot missions showed that it is very difficult to control a robot just by camera images. At the IRF, a new approach to overcome such problems was developed. By means of Projective Virtual Reality, we introduce a new, intuitive way of man-machine communication based on a combination of action planning and Virtual Reality methods. Using data-helmet and data-glove the user can immerse into the virtual world and interact with the virtual objects as he would do in reality. The Virtual Reality System derives the users intention from his actions and then projects the tasks in to the physical world by means of robots. The robots carry out the action physically that is equivalent to the users action in the virtual world. The developed Projective Virtual Reality System is of especially great use for space applications. During the joint project GETEX (German ETS-VII Experiment), the IRF realized the telerobotic ground station for the free flying robot ERA on board the Japanese satellite ETS-VII. During the mission in April 1999 the Virtual Reality based command interface turned out to be an ideally suited platform for the intuitive commanding and supervision of the robot in space. During the mission, it first had to be verified that the system is fully operational, but then out Japanese colleagues allowed to take the full control over the real robot by the Projective Virtual Reality System. The final paper will describe key issues of this approach and the results and experiences gained during the GETEX mission.

From the Volumetric Algorithm for Single-Tree Delineation Towards a Fully-Automated Process for the Generation of “Virtual Forests”

When we introduced the volumetric algorithm for single-tree delineation at the 3D GeoInfo 07, it was already a powerful algorithm with a high detection rate and the capability to generate trees for forestry units with only minimal user interaction. For the first test-area of 82 km2 this was acceptable, but as the test-areas grew, it showed that even the little user interaction does make the process laborious and strenuous. For currently envisaged test-areas of more than 1,000 km2, it is essential to further limit the required user interaction. In this paper we will show how to reduce the computational complexity of the volumetric algorithm and how to automatically calculate the free parameter that had to be set interactively in the earlier implementation. We will use the so called Receiver Operator Characteristic (ROC), an approach that is being used to model and imitate the human decision process when it comes to making a parameter decision in statistical processes. It turns out that this method, which is commonly used in other fields of scientific decision making, is also valuable for many other geo-information processes.