Hertzberg, Joachim
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Hertzberg, Joachim
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Hertzberg, Joachim
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Item-typ:Veröffentlichung, Development, Control, and Empirical Evaluation of the Six-Legged Robot SpaceClimber Designed for Extraterrestrial Crater Exploration(2013-02-20); ; ; In the recent past, mobile robots played an important role in the field of extraterrestrial surface exploration. Unfortunately, the currently available space exploration rovers do not provide the necessary mobility to reach scientifically interesting places in rough and steep terrain like boulder fields and craters. Multi-legged robots have proven to be a good solution to provide high mobility in unstructured environments. However, space missions place high demands on the system design, control, and performance which are hard to fulfill with such kinematically complex systems. This thesis focuses on the development, control, and evaluation of a six-legged robot for the purpose of lunar crater exploration considering the requirements arising from the envisaged mission scenario. The performance of the developed system is evaluated and optimized based on empirical data acquired in significant and reproducible experiments performed in a laboratory environment in order to show thecapability of the system to perform such a task and to provide a basis for the comparability with other mobile robotic solutions.Dissertation438 443 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Autonomous Operation of a Reconfigurable Multi-Robot System for Planetary Space Missions(2019-06-19); ; ; Reconfigurable robots can physically merge and form new types of composite systems. This ability leads to additional degrees of freedom for robot operations especially when dynamically composed robotic systems offer capabilities that none of the individual systems have. Research in the area of reconfigurable multi-robot systems has mainly been focused on swarm-based robots and thereby to systems with a high degree of modularity but a heavily restricted set of capabilities. In contrast, this thesis deals with heterogeneous robot teams comprising individually capable robots which are also modular and reconfigurable. In particular, the autonomous application of such reconfigurable multi-robot systems to enhance robotic space exploration missions is investigated. Exploiting the flexibility of a reconfigurable multi-robot system requires an appropriate system model and reasoner. Hence, this thesis introduces a special organisation model. This model accounts for the key characteristics of reconfigurable robots which are constrained by the availability and compatibility of hardware interfaces. A newly introduced mapping function between resource structures and functional properties permits to characterise dynamically created agent compositions. Since a combinatorial challenge lies in the identification of feasible and functionally suitable agents, this thesis further suggests bounding strategies to reason efficiently with composite robotic systems. This thesis proposes a mission planning algorithm which permits to exploit the flexibility of reconfigurable multi-robot systems. The implemented planner builds upon the developed organisation model so that multi-robot missions can be specified by high-level functionality constraints which are resolved to suitable combinations of robots. Furthermore, the planner synchronises robot activities over time and characterises plans according to three objectives: efficacy, efficiency and safety. The plannera s evaluation demonstrates an optimization of an exemplary space mission. This research is based on the parallel development of theoretical concepts and practical solutions while working with three reconfigurable multi-robot teams. The operation of a reconfigurable robotic team comes with practical constraints. Therefore, this thesis composes and evaluates an operational infrastructure which can serve as reference implementation. The identification and combination of applicable state-of-the-art technologies result in a distributed and dynamically extensible communication infrastructure which can maintain the properties of reconfigurable multi-robot systems. Field tests covering semi-autonomous and autonomous operation have been performed to characterise multi-robot missions and validate the autonomous control approach for reconfigurable multi-robot systems. The practical evaluation identified critical constraints and design elements for a successful application of reconfigurable multi-robot systems. Furthermore, the experiments point to improvements for the organisation model. This thesis is a wholistic approach to automate reconfigurable multi-robot systems. It identifies theoretical as well as practical challenges and it suggests effective solutions which permit an exploitation of an increased level of flexibility in future robotics missions.Dissertation1625 703 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, A novel three-finger dexterous hand with visual-based grasp planning and tactile-based stable grasping(2023-12-19); ; ; ; Robotic manipulation is a complex field that still faces numerous challenges. With the development of collaborative robots, the end-effector area is just beginning to gain traction, and electrically driven end-effectors are just starting to be widely used in the industry. One of the fundamental requirements for a robot to achieve practical applications is stable grasping. However, in reality, most stable grasping relies on specific static conditions and human experience. As the robotic industry continues to develop more complex and diverse applications, the need for stable grasping to support these high-level applications increases. To achieve more complex and stable grasping functions, a complex end-effector, such as a dexterous hand, becomes essential hardware. This thesis focuses on building a novel practical dexterous hand that can be used in robotic manipulation research. To make better use of the dexterous hand, visual-based grasp planning, and tactile-based stable grasping are necessary to form a stable grasping system. In this thesis, three crucial topics were selected and divided into three parts of the work: dexterous hand, grasp planning, and stable grasping. The dexterous hand part includes the main design work of a modular three-finger dexterous hand called DoraHand and partial work on another one called Eagle Shoal. The performance of the DoraHand and the tactile sensor module is showcased through experiments. Two-finger and five-finger versions of the DoraHand have also been developed and tested in real applications, providing a reliable hardware foundation for further research. The grasp planning part focuses on providing a grasp planning solution for the dexterous hand. As an essential function of using an end-effector, this part starts with an analytic solution that considers the limitations of the dexterous hand mechanism and grasp quality evaluation. A grasp planning network has been developed using both analytic and data-driven approaches. The network features a multi-finger grasp plan representation method and has been successfully verified. The stable grasping part is the final application of this thesis, where the hardware provides the foundation and the stable grasping algorithm utilizes the tactile sensor. An open-source visual-tactile dataset has been developed using the Eagle Shoal dexterous hand. The stable grasping algorithm, built based on this dataset, has been successfully verified with different types of end-effectors, including DoraHand and suction cup gripper. Overall, these three parts of work constitute the critical components of a stable grasping system using a dexterous hand. This system and related dataset enable further research in stable grasping and robotic manipulation. The primary objective of this thesis has been successfully achieved with the development of DoraHand, which has been used by over twenty research institutes and companies. The algorithms developed for grasp planning and stable grasping serve as a foundation for future research in this field, while the dataset can be used as a benchmark for comprehensive robotic research. Further development is needed to explore the potential applications of the dexterous hand in robotic manipulation.Dissertation383 505 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Evolutionary Legged Robotics(2019-02-14); ; ; Due to the technological advance, robotic systems become more and more interesting for industrial and home applications. Popular examples are given by robotic lawn mower, robot vacuum cleaner, and package drones. Beside the toy industry, legged robots are not as popular, although they have some clear advantages compared to wheeled systems. With their flexibility concerning the locomotion, they are able to adapt their walking pattern to different environments. For instance they can walk over obstacles and gaps or climb over rubble and stairs. Another possible advantage could be a redundancy for locomotion. A faulty motor in one limb could be compensated by other motors in the kinematic chain. As well, multiple failing legs can be compensated by an adapted walking pattern. Compared to this, the more complex mechatronic systems represent a major challenge to the construction and the control. This thesis is dedicated to the control of complex walking robots. Genetic algorithms are applied to generate walking patterns for different robots. The evolutionary development of walking patterns is done in a simulation software. Results of various approaches are transferred and tested on existing systems which have been developed at RIC/DFKI. Different robotic systems are used to evaluate the generality of the applied methods. Eventually, a method is developed that can be utilized, with a few system specific modifications, for a variety of legged robots. As basis for the development and investigation of several methods, software tools are designed to generalize the application of applying genetic algorithms to legged locomotion. These tools include a simulation environment, a behavior representation, a genetic algorithm and a learning and benchmark framework. The simulation environment is adapted to the behavior of real robotic systems via reference experiments. In addition, the simulation is extended by a foot contact model for loose surfaces. The evaluation of the genetic algorithm is done on several benchmark problems and compared to three existing algorithms. This thesis contributes to the state of the art in many areas. The developed methodology can easily be applied to several complex robotic systems due to its transferability. The genetic algorithm and the hierarchical behavior representation provide a new opportunity to control the generation of the offspring in an evolutionary process. In addition, the developed software tools are an important contribution for their respective research fields.Dissertation504 218 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Development, Evaluation and Validation of a Stereo Camera Underwater SLAM Algorithm(2014-03-12); ; ; In this work the development of an algorithm for visual underwater localization is described. It spans the complete process from the initial idea, the development of a suitable underwater vehicle for testing to the algorithm's experimental validation in real underwater environments. Besides the development and validation of the visual SLAM algorithm, the methodology for its evaluation is a key aspect of this work. The resulting SURE-SLAM algorithm uses a stereo camera system and basic vehicle sensors (AHRS, DPS) to compute a complete, error-bounded localization solution for underwater vehicles in real-time with similar quality as state-of-the-art acoustically stabilized dead-reckoning approaches. The robustness of the algorithm as well as its limitations and failure-cases are established by extensive field testing with the AUV Dagon, which was developed during this thesis as test and evaluation vehicle.Dissertation946 125 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Prediction of Object Position based on Probabilistic Qualitative Spatial Relations(2017-07-26); ; ; Due to recent and extensive advancements in the robotic and artificial intelligence fields, intelligent systems can be found, with increasing frequency, in many areas of daily life. From industrial and surgical purposes to space robots, such complex systems are present. However, as demands for robotics systems increase, sophisticated algorithms for use in robotic areas such as perception, navigation, or manipulation are required. Although some algorithms for such purposes exist, there are still open questions and challenges that must be addressed. Although robots are primarily used in the manufacturing industry, which has since been revolutionized by their precision and speed, there is a growing trend towards using service and personal robotics applications. The latter in particular must interact with humans naturally and effectively manage their environments, such as offices and homes. In contrast to the systems used in an industrial context, systems such as personal robots do not act in a predefined and fixed environment. Rather, these intelligent systems need an intrinsic comprehension of human environments to be able to support people in their daily life and manage common tasks such as preparing a breakfast table or cleaning a room. Crucially, these new robot systems require an entirely new level of capabilities to act in dynamic human environments. This thesis addresses how qualitative spatial relations can be used to find an objecta s most probable location and thus guide the search for a sought object. Because current approaches focus mainly on crisp, two-dimensional relations, which are not directly suitable for use in three-dimensional real-world applications, a formalism for a new type of spatial relations is proposed in this work. This theoretical approach is then applied on real-world data to evaluate its applicability for robotics purposes. The resulting validation of the approach demonstrates that the developed method performs well and can be used to enhance search for objects.Dissertation374 158