UNCONTROLLED MANIFOLD ANALYSIS OF JOINT ANGLE VARIABILITY DURING TABLE TENNIS FOREHAND

The purpose of this study was to evaluate the variance structure of the trunk and racket arm joint angles in the table tennis topspin forehand in relation to the control of racket orientation using the uncontrolled manifold (UCM) approach. Seventeen (9 advanced and 8 intermediate) male collegiate table tennis players performed the strokes against backspin. The UCM analysis was conducted using 30 trial data per each participant. The degree of redundancy exploitation to stabilize the racket vertical and horizontal angles were not significantly different between the two performance levels, suggesting that the ability to exploit joint configuration redundancy may not contribute to achieving higher performance in sport hitting skill. The degree of redundancy exploitation is highest at ball impact and this result may reflect that the table tennis forehand is a fast interceptive task

An uncontrolled manifold analysis of arm joint variability in virtual planar position and orientation tele-manipulation

Objective: In teleoperated robot-assisted tasks, the user interacts with manipulators to finely control remote tools. Manipulation of robotic devices, characterized by specific kinematic and dynamic proprieties, is a complex task for the human sensorimotor system due to the inherent biomechanical and neuronal redundancies that characterize the human arm and its control. We investigate how master devices with different kinematics structures and how different task constraints influence users capabilities in exploiting arm redundancy. Methods: A virtual teleoperation workbench was designed and the arm kinematics of seven users was acquired during the execution of two planar virtual tasks, involving either the control of position only or position-orientation of a tool. Using the UnControlled Manifold Analysis of arm joint variability we estimated the logarithmic ratio between task irrelevant and the task relevant manifolds (Rv). Results: The Rv values obtained in the position-orientation task were higher than in the position only task while no differences were found between the master devices. A modulation of Rv was found through the execution of the position task and a positive correlation was found between task performance and redundancy exploitation. Conclusion: Users exploited additional portions of arm redundancy when dealing with the tool orientation. The Rv modulation seems influenced by the task constraints and by the users possibility of reconfiguring the arm position. Significance: This work advances the general understanding of the exploitation of arm redundancy in complex tasks, and can improve the development of future robotic devices

Advanced Ergonomics in Laparoscopic Surgery

Applied ergonomics is very important in minimally invasive surgery (MIS), especially with the introduction of robotized techniques that have changed the surgeons’ work conditions. However, the main aim remains the engineering to enable the compatibility of fulfillment of surgeons’ tasks in a physical, logical, and organizational environment with security, comfort, and efficiency. Ergonomics contribution is oriented both to design and redesign utilized material and to work organization. Epidemiological studies have shown the appearance of musculoskeletal pathologies in surgeons performing MIS; therefore, it is relevant to identify the intensity, frequency, and duration of risk factors (posture, repeatability, level of effort, touch pressure, and vibration if relevant) associated with this profession. A further relevant consequence of the effort applied during MIS is local muscle fatigue (LMF), an important factor to consider in musculoskeletal pathologies. The aim of this chapter is to present different methodological approaches by employing most advanced technologies to define the most appropriate posture that surgeons should adopt during MIS to decrease LMF apparition risk level and at the same time to increase capacity to variate the posture without reducing the precision task performance

Recent Advances in Laparoscopic Surgery

The implementation of laparoscopy has revolutionized surgery over the past few years, incorporating significant benefits for the patient. However, this evolution has also entailed many technical obstacles for surgeons. This book is for readers wanting to learn more about recent surgical techniques and technologies. Topics cover novel sophisticated approaches for single-site surgery, natural orifice transluminal endoscopic surgery, and transanal surgery, among others. Also included are reviews of new innovative surgical devices, robotic platforms, and methodological guidelines for improving surgical performance and surgeon ergonomics

A task analysis approach to quantify bottlenecks in task completion time of telemanipulated maintenance

Telemanipulation techniques allow for human-in-the-loop assembly and maintenance tasks in otherwise inaccessible environments. Although it comes with limitations in achieved performance – required strict operator selection and extensive training are widely encountered – there is very little quantitative insight in the exact problems operators encounter during task execution. This paper provides a novel hierarchical task analysis approach to identify the most time-consuming subtask elements and to quantify the potential room for performance improvement during telemanipulated maintenance tasks. The approach is illustrated with a human factors case study in which 5 subjects performed six generic maintenance tasks, using a six degree of freedom master device connected to a simulated task environment. Overall it can be concluded that the proposed three phased task analysis is a useful tool to guide improvements since it is able to relate high-level problems (e.g. large variability) to behaviour on lower task-levels. For the case study, the largest potential for improvement was found for specific subtasks characterized by complex contact transitions and precise control of tool orientation, and in the reduction of variation of the task execution.</p

Unraveling the Effects of Expertise and Fatigue on Kinematics and Stride-to-Stride Variability in Running

Unser Körper ermöglicht es uns, ohne große Anstrengung komplexe Bewegungen auszuführen. Aufgrund der Vielzahl von Freiheitsgraden (DoF) im Muskel-Skelett-System ist unser Körper ein hochredundantes System. Für jede denkbare Bewegung gibt es daher mehrere Lösungsmöglichkeiten, welche wiederum zu einer Vielzahl an Bewegungsausführungen führen. Von außen betrachtet liegt die Vermutung nahe, dass innerhalb einer zyklischen Bewegung, wie z.B. dem Laufen, immer wieder der gleiche Bewegungsablauf ausgeführt wird. Dies führt oft zu der Annahme, dass die Beobachtung eines einzigen Laufzyklus ausreicht, um die Biomechanik des Laufens zu analysieren. Dabei werden allerdings Informationen übersehen, die in den Variationen zwischen aufeinanderfolgenden Zyklen liegen. Tatsächlich könnte eine reine Reproduktion desselben Laufzyklus unter gleichen Bedingungen zu Verletzungen führen, da immer dieselben Strukturen in demselben Maße belastet werden würden. Jedoch ist der Zustand des Läufers und seiner Randbedingungen von Laufzyklus zu Laufzyklus nicht immer identisch, daher ist eine exakte Reproduktion desselben Bewegungsmusters unwahrscheinlich. Eine mögliche Veränderung der Randbedingungen könnte das Auftreten von Ermüdung sein, welche bei Ausdauersportarten unvermeidlich ist. Die Vielzahl gleichwertiger Bewegungslösungen und die daraus resultierende Variabilität zwischen einzelnen Laufzyklen eines Läufers sind daher wertvolle Merkmale und ein wichtiges Thema für Forschungsarbeiten im Kontext der menschlichen Bewegungskoordination. Auf dem Forschungsgebiet der Bewegungsvariabilität wurden zwei vielversprechende spezifische Methoden entwickelt und auf biomechanische Daten angewendet: die Uncontrolled Manifold-Methode (UCM) und die Tolerance Noise Covariation-Methode (TNC). Die UCM hat ihren Ursprung im Forschungsfeld der motorischen Kontrolle, wohingegen die TNC aus dem Bereich des motorischen Lernens kommt. Mit Hilfe der UCM und der TNC Methoden wird analysiert, wie die Variabilität auf der Ebene der Gelenkwinkel mit der Variabilität der Zielgröße zusammenhängt. Sie wurden hauptsächlich auf eingeschränkte Bewegungen mit nur wenigen DoF angewendet und kaum zur Untersuchung von Ganzkörperbewegungen, wie z.B. des Laufens, genutzt. Bei Untersuchungen des Gehens wurde festgestellt, dass trotz Zyklus-zu-Zyklus Variabilität (SSV) auf unterschiedlichen Ebenen (z.B. Gelenkwinkel) diese so kanalisiert werden kann, dass eine Zielgröße (z.B. Körperschwerpunk, CoM) über die Zyklen hinweg annähernd konstant bleibt. Diese Arbeit erörtert auf der Basis von fünf Studien, wie sich Expertise und Ermüdung auf die Laufkinematik auswirken, indem sie nicht nur eine biomechanische Analyse der Effekte von Ermüdung auf die Lauf-Kinematik durchführt, sondern auch komplexe Methoden zur Analyse der Bewegungsvariabilität anwendet. Da diese Methoden in der internationalen sportwissenschaftlichen Forschung bisher kaum Anwendung gefunden haben, wird mit der vorliegenden Arbeit auch geprüft, ob sich die anhand von einfachen, experimentellen Paradigmen der Grundlagenforschung entwickelten Methoden, gewinnbringend auf sportwissenschaftliche Problemstellungen übertragen lassen. In der ersten Studie wurden die Auswirkungen von Expertise auf die SSV des CoM beim Laufen bei 10 und 15 km/h analysiert. Novizen zeigten bei 15 km/h eine größere Variabilität als Experten. In der zweiten Studie wurde ein klassischer biomechanischer Ansatz gewählt, um die Ermüdungsreaktionen von erfahrenen Läufern zu untersuchen. Dabei wurden Veränderungen sowohl in Raum-Zeit- und Steifigkeitsparametern, als auch in der Gelenkkinematik gefunden. Diese Ergebnisse zeigten, dass die Kinematik im ermüdeten Zustand deutlich verändert ist. Die dritte Studie erweiterte diese Erkenntnisse durch die Verwendung der UCM-Methode. Dabei wurde ein probandenspezifisches 3D-Modell für den menschlichen Körper eingeführt, um den Ganzkörper-CoM genau berechnen zu können. Es wurden geringe Veränderungen bei Ermüdung gefunden. Dies zeigte, dass erfahrene Läufer in der Lage sind, ihre CoM-Trajektorie auch in einem ermüdeten Zustand zu kontrollieren. In der vierten Studie wurden diese Ergebnisse durch die Verwendung der TNC-Methode erweitert. Es zeigte sich, dass die Variabilität des CoM sowohl in medio-lateraler als auch in vertikaler Richtung mit Ermüdung zunimmt. In der fünften Studie wurde wieder ein klassischer biomechanischer Ansatz gewählt, um die Reaktionen auf Ermüdung zu charakterisieren, dieses Mal bei Lauf-Novizen. Es wurden keine Veränderungen in den Raum-Zeit- und Steifigkeitsparametern gefunden, obwohl die Gelenkkinematik durch die Ermüdung beeinflusst wurde. Diese Ergebnisse deuten darauf hin, dass Novizen möglicherweise Strategien fehlen, um eine konstante Laufgeschwindigkeit unter Ermüdung beizubehalten. Mit dieser Studienreihe wird das Wissen über die Auswirkungen von Expertise und Ermüdung auf die Kinematik und SSV beim Laufen erweitert. Nachdem die grundsätzliche Anwendbarkeit von neuen Ansätzen, wie der UCM oder der TNC Methode, auf komplexe sportwissenschaftliche Probleme gezeigt wurde, können diese Methoden bei der Anwendung auf praxisorientierte Probleme in der Sportwissenschaft geprüft und zu verbessert werden

Exploring Robot Teleoperation in Virtual Reality

This thesis presents research on VR-based robot teleoperation with a focus on remote environment visualisation in virtual reality, the effects of remote environment reconstruction scale in virtual reality on the human-operator's ability to control the robot and human-operator's visual attention patterns when teleoperating a robot from virtual reality. A VR-based robot teleoperation framework was developed, it is compatible with various robotic systems and cameras, allowing for teleoperation and supervised control with any ROS-compatible robot and visualisation of the environment through any ROS-compatible RGB and RGBD cameras. The framework includes mapping, segmentation, tactile exploration, and non-physically demanding VR interface navigation and controls through any Unity-compatible VR headset and controllers or haptic devices. Point clouds are a common way to visualise remote environments in 3D, but they often have distortions and occlusions, making it difficult to accurately represent objects' textures. This can lead to poor decision-making during teleoperation if objects are inaccurately represented in the VR reconstruction. A study using an end-effector-mounted RGBD camera with OctoMap mapping of the remote environment was conducted to explore the remote environment with fewer point cloud distortions and occlusions while using a relatively small bandwidth. Additionally, a tactile exploration study proposed a novel method for visually presenting information about objects' materials in the VR interface, to improve the operator's decision-making and address the challenges of point cloud visualisation. Two studies have been conducted to understand the effect of virtual world dynamic scaling on teleoperation flow. The first study investigated the use of rate mode control with constant and variable mapping of the operator's joystick position to the speed (rate) of the robot's end-effector, depending on the virtual world scale. The results showed that variable mapping allowed participants to teleoperate the robot more effectively but at the cost of increased perceived workload. The second study compared how operators used a virtual world scale in supervised control, comparing the virtual world scale of participants at the beginning and end of a 3-day experiment. The results showed that as operators got better at the task they as a group used a different virtual world scale, and participants' prior video gaming experience also affected the virtual world scale chosen by operators. Similarly, the human-operator's visual attention study has investigated how their visual attention changes as they become better at teleoperating a robot using the framework. The results revealed the most important objects in the VR reconstructed remote environment as indicated by operators' visual attention patterns as well as their visual priorities shifts as they got better at teleoperating the robot. The study also demonstrated that operators’ prior video gaming experience affects their ability to teleoperate the robot and their visual attention behaviours

Exploring Robot Teleoperation in Virtual Reality

This thesis presents research on VR-based robot teleoperation with a focus on remote environment visualisation in virtual reality, the effects of remote environment reconstruction scale in virtual reality on the human-operator's ability to control the robot and human-operator's visual attention patterns when teleoperating a robot from virtual reality. A VR-based robot teleoperation framework was developed, it is compatible with various robotic systems and cameras, allowing for teleoperation and supervised control with any ROS-compatible robot and visualisation of the environment through any ROS-compatible RGB and RGBD cameras. The framework includes mapping, segmentation, tactile exploration, and non-physically demanding VR interface navigation and controls through any Unity-compatible VR headset and controllers or haptic devices. Point clouds are a common way to visualise remote environments in 3D, but they often have distortions and occlusions, making it difficult to accurately represent objects' textures. This can lead to poor decision-making during teleoperation if objects are inaccurately represented in the VR reconstruction. A study using an end-effector-mounted RGBD camera with OctoMap mapping of the remote environment was conducted to explore the remote environment with fewer point cloud distortions and occlusions while using a relatively small bandwidth. Additionally, a tactile exploration study proposed a novel method for visually presenting information about objects' materials in the VR interface, to improve the operator's decision-making and address the challenges of point cloud visualisation. Two studies have been conducted to understand the effect of virtual world dynamic scaling on teleoperation flow. The first study investigated the use of rate mode control with constant and variable mapping of the operator's joystick position to the speed (rate) of the robot's end-effector, depending on the virtual world scale. The results showed that variable mapping allowed participants to teleoperate the robot more effectively but at the cost of increased perceived workload. The second study compared how operators used a virtual world scale in supervised control, comparing the virtual world scale of participants at the beginning and end of a 3-day experiment. The results showed that as operators got better at the task they as a group used a different virtual world scale, and participants' prior video gaming experience also affected the virtual world scale chosen by operators. Similarly, the human-operator's visual attention study has investigated how their visual attention changes as they become better at teleoperating a robot using the framework. The results revealed the most important objects in the VR reconstructed remote environment as indicated by operators' visual attention patterns as well as their visual priorities shifts as they got better at teleoperating the robot. The study also demonstrated that operators’ prior video gaming experience affects their ability to teleoperate the robot and their visual attention behaviours