Impedance Control on Arbitrary Surfaces for Ultrasound Scanning using Discrete Differential Geometry

We propose an approach to robotic ultrasound scanning and interaction control with arbitrary surfaces using a passivity-based impedance control scheme. First, we introduce task coordinates depending on the geometry of the surface, which enable hands-on guidance of the robot along the surface, as well as teleoperated and autonomous ultrasound image acquisition. Our coordinates allow controlling the signed distance of the robot to the surface and alignment of the tool to the surface normal using classical impedance control. This corresponds to implicitly obtaining a foliation of parallel surfaces. By setting the desired signed distance negative, i.e., into the surface, we obtain passive contact forces and simultaneously provide an intuitive way to control the maximum penetration depth into the surface. We extend the approach to also incorporate coordinates allowing to control the specific point on the surface and, automatically, on all parallel surfaces. Finally, we demonstrate the performance of the controller on the seven degrees of freedom lightweight robot DLR Miro: the robot tracks complex trajectories while accurately keeping the desired distance to the surface and applying an almost constant contact force. Finally, we compare the approach to the state of the art

Task-Specific Robot Base Pose Optimization for Robot-Assisted Surgeries

Preoperative planning and intra-operative system setup are crucial steps to successfully integrate robotically assisted surgical systems (RASS) into the operating room. Efficiency in terms of setup planning directly affects the overall procedural costs and increases acceptance of RASS by surgeons and clinical personnel. Due to the kinematic limitations of RASS, selecting an optimal robot base location and surgery access point for the patient is essential to avoid potentially critical complications due to reachability issues. To this end, this work proposes a novel versatile method for RASS setup and planning based on robot capability maps (CMAPs). CMAPs are a common tool to perform workspace analysis in robotics, as they are in general applicable to any robot kinematics. However, CMAPs have not been completely exploited so far for RASS setup and planning. By adapting global CMAPs to surgical procedure-specific tasks and constraints, a novel RASS capability map (RASSCMAP) is generated. Furthermore, RASSCMAPs can be derived to also comply with kinematic access constraints such as access points in laparoscopy. RASSCMAPs are versatile and applicable to any kind of surgical procedure; they can be used on the one hand for aiding in intra-operative experience-based system setup by visualizing online the robot’s capability to perform a task. On the other hand, they can be used to find the optimal setup by applying a multi-objective optimization based on a genetic algorithm preoperatively, which is then transfered to the operating room during system setup. To illustrate these applications, the method is evaluated in two different use cases, namely, pedicle screw placement in vertebral fixation procedures and general laparoscopy. The proposed RASSCMAPs help in increasing the overall clinical value of RASS by reducing system setup time and guaranteeing proper robot reachability to successfully perform the intended surgerie

An Introduction to Robotically Assisted Surgical Systems: Current Developments and Focus Areas of Research

Robotic assistance systems for diagnosis and therapy have become technically mature and widely available. Thus, they play an increasingly important role in patient care. This paper provides an overview of the general concepts of robotically assisted surgical systems, briefly revisiting historical and current developments in the surgical robotics market and discussing current focus areas of research. Comprehensiveness cannot be achieved in this format, but besides the general overview, references to further readings and more comprehensive reviews with regard to particular aspects are given. Therefore, the work at hand is considered as an introductory paper into the topic and especially addresses investigators, researchers, medical device manufacturers, and clinicians, who are new to this field

A Robotic System for Solo Surgery in Flexible Ureterorenoscopy

Urolithiasis is a common disease with increasing prevalence across all ages. A common treatment option for smaller kidney stones is flexible ureterorenoscopy (fURS), where a flexible ureteroscope (FU) is used for stone removal and to inspect the renal collecting system. The handling of the flexible ureteroscope and end effectors (EEs), however, is challenging and requires two surgeons. In this article, we introduce a modular robotic system for endoscope manipulation, which enables solo surgery (SSU) and is adaptable to various hand-held FUs. Both the developed hardware components and the proposed workflow and its representation in software are described. We then present and discuss the results of an initial user study. Finally, we describe subsequent developmental steps towards more extensive testing by clinical staff

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

Entwicklung und Anwendung von Methoden zur kinematischen Kalibration eines Leichtbauroboters

Die Kalibration des kinematischen Modells eines Roboters spielt für seine Pose- bzw. Absolut- Genauigkeit eine entscheidende Rolle. Diese Arbeit behandelt die Entwicklung zweier Kalibrationsverfahren und deren Durchführung mit einem Leichtbauroboter mit 7 Freiheitsgraden, der in der robotergestützten Chirurgie eingesetzt werden soll. Zum einen wird eine Kreisbogenanalyse zur Kalibration verwendet. Zum anderen wird eine statische 6D-Kalibration entwickelt, die auf ähnliche Weise in der Industrie angewendet wird. Nach einer verfahrensspezifischen Planung und Vermessung der nötigen Trajektorien mit einem externen Trackingsystem werden die Kalibrationsverfahren durchgeführt. Im Anschluss werden die Ergebnisse mittels einer Pose – Genauigkeitsuntersuchung über den gesamten Arbeitsraum des Roboters und mit Hilfe eines Pose – Genauigkeitstests nach DIN EN ISO 9283 verifiziert. Durch die statische 6D-Kalibration konnten Steigerungen der Pose-Genauigkeit über 60 Posen im gesamten Arbeitsraum, die von der Kalibration unabhängig waren, von ca. 5mm auf ca. 1,5mm erzielt werden. Bei der Kreisbogenanalyse wurden ähnliche Steigerungen erreicht. Insgesamt wurden zwei leistungsstarke Kalibrationsverfahren entwickelt, wobei der Aufwand bei der Durchführung der statischen 6D-Kalibration etwas geringer ist als bei der Kreisbogenanalyse. Die Erweiterung der statischen 6D-Kalibration auf ein elastisches kinematisches Robotermodell ist leicht möglich

Kalibration des medizinischen Leichtbauroboters MIRO hinsichtlich der elastischen Roboterkinematik, der internen Momentensensorik und der Massenparameter

Die Kalibration von Robotern ist eine vielfach untersuchte Problemstellung in der Robotik. Durch die Entwicklung immer komplexerer Robotersysteme hinsichtlich ihrer Sensorik bzw. ihrer Bauweise müssen die vorhandenen Methoden zur Kalibration weiterentwickelt und auf den jeweiligen Robotertyp angepasst werden. Nach dem derzeitigen Stand der Technik werden Sensorik, Dämpfungs- und Elastizitätsparameter vor dem Zusammenbau kalibriert, wobei die Gelenke einzeln auf einem Prüfstand untersucht werden. Diese Arbeit beschäftigt sich mit der Entwicklung einer Kalibrationsmethode für Leichtbauroboter in zusammengebautem Zustand. Die Gelenke und Strukturkomponenten sind hierbei als elastisch anzunehmen und verfügen über integrierte Drehmomentensensorik verfügen. Angewandt wird dieses Verfahren auf den medizinischen Leichtbauroboter MIRO, dessen Einsatz in der robotergestützten Chirurgie geplant ist. Bei dem Verfahren handelt es sich um einen schrittweisen Prozess. Im ersten Schritt werden die kinematischen Zusammenhänge, sowie die elastischen Eigenschaften des Roboters identifiziert. Daraufhin folgt die Modellierung und Kalibration der internen Drehmomentensensorik. Ein dritter Schritt ist nötig um die Massen und Massenschwerpunkte der einzelnen Roboterglieder zu identifizieren. Die Durchführung der einzelnen Kalibrationsschritte und deren Verifikation zeigen die Tauglichkeit des Verfahrens. Die Pose-Genauigkeit des MIRO kann von 5 mm auf 0.5 mm translatorisch und rotatorisch von 3° auf 0.3° verbessert werden. Auch die Messabweichungen der Drehmomentensensoren können bis zu 85 % verringert werden. Für folgende Arbeiten wird vorgeschlagen den Kalibrationsprozess iterativ anzuwenden, um den Einfluss der fehlerhaften Drehmomentenmessung im ersten Kalibrationsschritt zu kompensieren

Model-free robot anomaly detection

Safety is one of the key issues in the use of robots, especially when human–robot interaction is targeted. Although unforeseen environment situations, such as collisions or unexpected user interaction, can be handled with specially tailored control algorithms, hard- or software failures typically lead to situations where too large torques are controlled, which cause an emergency state: hitting an end stop, exceeding a torque, and so on—which often halts the robot when it is too late. No sufficiently fast and reliable methods exist which can early detect faults in the abundance of sensor and controller data. This is especially difficult since, in most cases, no anomaly data are available. In this paper we introduce a new robot anomaly detection system (RADS) which can cope with abundant data in which no or very little anomaly information is present