Trilaterale Regelung für einen Telechirurgietrainer

Während minimalinvasiver Operationen in der Chirurgierobotik müssen u.a. komplizierte Bewegungsabläufe wie das Verknoten einer Naht auf kleinstem Raum innerhalb des Körpers ausgeführt werden. Um solche Manipulationen schnell zu erlernen, müssen diese einem unerfahrenen Chirurgen durch einen zweiten, mit dem jeweiligen Robotersystem erfahrenen Chirurgen antrainiert werden. Dieser Spezialist soll sich aus Kostengründen auf einem anderen Kontinent befinden dürfen, weshalb im Kommunikationskanal des zu entwickelnden Trainingssystems hohe instabilisierende Zeitverzögerungen auftreten können. Im Sinne des Trainingserfolgs soll eine bestmögliche Transparenz zwischen Operatoren und Umgebung erzielt werden

Time Domain Control for Passive Variable Motion and Force Scaling in Delayed Teleoperation

Scaling of motion and forces has always been of high relevance in teleoperation setups since it allows the adaptation of workspaces of master and slave devices or to increase precision. Teleoperation setups are often affected by a delay in the communication channel. Most state of the art control approaches that guarantee stability despite delay are based on the passivity criterion which is highly restrictive to standard scaling methods. This paper proposes different time domain control concepts that regulate the motion or force scaling based on the energy flow in delayed teleoperation systems. The approach focuses on setups with motion down-scaling and is applicable to variable motion and impedance scaling. The scaling control is integrated in a state of the art time delay control concept and its performance is analyzed in experiments

Robotisch bewegt - Interaktive Bewegungssimulation

Wie fährt man die Fahrzeuge der Zukunft? Um einen physisch realistischen Eindruck zu erhalten, setzt das Deutsche Zentrum für Luft-und Raumfahrt (DLR) eine robotische Bewegungsplattform zur Entwicklung und Bewertung zukünftiger Stellteile im Automobil ein

Light-field head-mounted displays reduce the visual effort: A user study

Head-mounted displays (HMD) allow the visualization of virtual content and the change of view perspectives in a virtual reality (VR). Besides entertainment purposes, such displays also find application in augmented reality, VR training or tele-robotic systems. The quality of visual feedback plays a key role for the interaction performance in such setups. In the last years, high-end computers and displays led to the reduction of simulator sickness regarding nausea symptoms, while new visualization technologies are required to further reduce oculomotor and disorientation symptoms. The so-called vergence-accommodation conflict (VAC) in standard stereoscopic displays prevents intense use of 3D displays, so far. The VAC describes the visual mismatch between the projected stereoscopic 3D image and the optical distance to the HMD screen. This conflict can be solved by using displays with correct focal distance. The light-field HMD of this study provides a close-to-continuous depth and high image resolution enabling a highly natural visualization. This paper presents the first user-study on the visual comfort of light-field displays with a close-to-market HMD based on complex interaction tasks. The results provide first evidence that the light-field technology brings clear benefits to the user in terms of physical use comfort, workload and depth matching performance

Deflection-Domain Passivity Control of Variable Stiffnesses Based on Potential Energy Reference

With emerging capabilities, robots will advance gradually into human environments in the near future. Thereby, safety and robustness is currently tackled through intrinsically soft robotics or variable impedances, mainly stiffnesses. In tele-operation, for instance, the control stiffness can be adapted to a measured arm impedance of the operator to stiffen the robot only when required for a manipulation task. Thus, humans or moving objects in the robot's environment are protected from hard collisions. Independent from its realization through hardware or software, the stability of the variation needs to be ensured through control strategies since energy is potentially introduced into the robotic system. This work presents a novel gradient-based passivity control concept for variable stiffnesses. In contrast to state-of-the-art methods, the approach is based on a potential energy storage reference and prevents phases of zero stiffness through deflection-domain control. I.e., according to the energy storage, the stiffness variation over the spring deflection is controlled to ensure passivity. Experiments confirm the functionality of the approach and its robustness against delayed communication and active environments

Tele-Robotics VR with Holographic Vision in Immersive Video

We present a first-of-its-kind end-to-end tele-robotic VR system where the user operates a robot arm remotely, while being virtually immersed into the scene through force feedback and holographic vision. In contrast to stereoscopic head mounted displays that only provide depth perception to the user, the holographic vision device projects a light field, additionally allowing the user to correctly accommodate his/her eyes to the perceived depth of the scene's objects. The highly improved immersive user experience results in less fatigue in the tele-operator's daily work, creating safer and/or longer working conditions. The core technology relies on recent advances in immersive video coding for audio-visual transmission developed within the MPEG standardization committee. Virtual viewpoints are synthesized for the tele-operator's viewing direction from a couple of colour and depth fixed video feeds. Besides of the display hardware and its GPU-enabled view synthesis driver, the biggest challenge hides in obtaining high-quality and reliable depth images from low-cost depth sensing devices. Specialized depth refinement tools have been developed for running in real- time at zero delay within the end-to-end tele-robotic immersive video pipeline, which must remain interactive by essence. Various modules work asynchronously and efficiently at their own pace, with the acquisition devices typically being limited to 30 frames per second (fps), while the holographic headset updates its projected light field at up to 240 fps. Such modular approach ensures high genericity over a wide range of free navigation VR/XR applications, also beyond the tele-robotic one presented in this paper

Model-Augmented Haptic Telemanipulation: Concept, Retrospective Overview, and Current Use Cases

Certain telerobotic applications, including telerobotics in space, pose particularly demanding challenges to both technology and humans. Traditional bilateral telemanipulation approaches often cannot be used in such applications due to technical and physical limitations such as long and varying delays, packet loss, and limited bandwidth, as well as high reliability, precision, and task duration requirements. In order to close this gap, we research model-augmented haptic telemanipulation (MATM) that uses two kinds of models: a remote model that enables shared autonomous functionality of the teleoperated robot, and a local model that aims to generate assistive augmented haptic feedback for the human operator. Several technological methods that form the backbone of the MATM approach have already been successfully demonstrated in accomplished telerobotic space missions. On this basis, we have applied our approach in more recent research to applications in the fields of orbital robotics, telesurgery, caregiving, and telenavigation. In the course of this work, we have advanced specific aspects of the approach that were of particular importance for each respective application, especially shared autonomy, and haptic augmentation. This overview paper discusses the MATM approach in detail, presents the latest research results of the various technologies encompassed within this approach, provides a retrospective of DLR's telerobotic space missions, demonstrates the broad application potential of MATM based on the aforementioned use cases, and outlines lessons learned and open challenges

Introduction to Surface Avatar: the First Heterogeneous Robotic Team to be Commanded with Scalable Autonomy from the ISS

Robotics is vital to the continued development toward Lunar and Martian exploration, in-situ resource utilization, and surface infrastructure construction. Large-scale extra-terrestrial missions will require teams of robots with different, complementary capabilities, together with a powerful, intuitive user interface for effective commanding. We introduce Surface Avatar, the newest ISS-to-Earth telerobotic experiment series, to be conducted in 2022-2024. Spearheaded by DLR, together with ESA, Surface Avatar builds on expertise on commanding robots with different levels of autonomy from our past telerobotic experiments: Kontur-2, Haptics, Interact, SUPVIS Justin, and Analog-1. A team of four heterogeneous robots in a multi-site analog environment at DLR are at the command of a crew member on the ISS. The team has a humanoid robot for dexterous object handling, construction and maintenance; a rover for long traverses and sample acquisition; a quadrupedal robot for scouting and exploring difficult terrains; and a lander with robotic arm for component delivery and sample stowage. The crew's command terminal is multimodal, with an intuitive graphical user interface, 3-DOF joystick, and 7-DOF input device with force-feedback. The autonomy of any robot can be scaled up and down depending on the task and the astronaut's preference: acting as an avatar of the crew in haptically-coupled telepresence, or receiving task-level commands like an intelligent co-worker. Through crew performing collaborative tasks in exploration and construction scenarios, we hope to gain insight into how to optimally command robots in a future space mission. This paper presents findings from the first preliminary session in June 2022, and discusses the way forward in the planned experiment sessions

Development of a third rotational input on a force feedback joystick

Habitualmente los joysticks con realimentación de fuerza incorporan dos grados de libertad que son su�cientes para muchos usos. Sin embargo, hay casos en los que un tercer grado de libertad que también tenga realimentación de fuerza es útil como entrada, por ejemplo cuando surge la necesidad de controlar un robot móvil con cuatro ruedas independendientes. Este tipo de robot ha sido desarrollado en DLR: el Robomobil. Un joystick de tres grados de libertad sustituir ía los elementos tradicionales de conducción (volante, freno y acelerador) y posibilitaría al conductor comandar los movimientos longitudinales, laterales y rotatorios independientemente. Las ventajas de este sistema son muchas, tales como: la integración de los controles de conducción en un único aparato, la posibilidad de comandar movimientos independientemente, o el ser compatible en términos de direcciones, por nombrar algunos ejemplos. El objetivo de este proyecto fue investigar qué tipo de entrada era adecuada para el tercer grado de libertad y cómo afectaba al control de un joystick de tres grados de libertad el acoplamiento de la cinématica del antebrazo humano. Teniendo esto en cuenta, se realizó un estudio de usuarios (un robot de siete grados de libertad emuló los distintos modos del joystick, y con un aparato háptico, el Spacemouse, se comprobó si era adecuado separar alguno de los grados de libertad en dos aparatos). Finalmente se llevó a cabo el diseño mecánico para la implementación del tercer grado de libertad rotacional en un joystick de dos grados de libertad existente en DLR

A peer-to-peer Trilateral Passivity Control for delayed collaborative Teleoperation

In this paper a trilateral Multi-Master-Single-Slave-System with control authority allocation between two human operators is proposed. The authority coefficient permits to slide the dominant role between the operators. They can simultaneously execute a task in a collaborative way or a trainee might haptically only observe the task, while an expert is in full control. The master devices are connected with each other and the slave robot peer to peer without a central processing unit in a equitable way. The system design is general in that it allows delayed communication and different coupling causalities between masters and slave, which can be located far from each other. The Time Domain Passivity Control Approach guarantees passivity of the network in the presence of communication delays. The methods presented are sustained with simulations and experiments using different authority coefficients