Kinetic Analysis of Active Omni Wheel With Barrel-Shaped Rollers for Avoiding Slippage and Vibration

Paper No: JMR-23-1080Omnidirectional mobility is required for the efficient movement of transport vehicles in factories and warehouses. To meet this requirement, the active omni wheel with barrel-shaped rollers (AOWBR) was previously proposed. The barrel-shaped rollers are arranged around the outer circumference of the main wheel of the AOWBR. This structure is expected to be effective in suppressing vibration during vehicle movement. The transmission roller drives the outer roller via a friction drive, which actively moves the AOWBR in the lateral direction. However, the friction drive may cause slippage between the transmission roller and the outer roller. To solve this problem, this study investigates the effects of the design parameters for an AOWBR on vibration and wheel slippage. The kinetic models of the wheel main body, transmission roller, and outer roller are established. Then, simulations are carried out using the kinetic models for various structural parameter values. The simulation results show that a softer rubber block installed in the support mechanism of the outer roller contributes to reduce wheel slippage but cause larger vibration, and that a larger setting angle between the transmission and outer rollers contributes to reduce slippage and vibration. Finally, comparison experiments are conducted on two types of prototype to verify the simulation results

Climbing and Walking Robots

With the advancement of technology, new exciting approaches enable us to render mobile robotic systems more versatile, robust and cost-efficient. Some researchers combine climbing and walking techniques with a modular approach, a reconfigurable approach, or a swarm approach to realize novel prototypes as flexible mobile robotic platforms featuring all necessary locomotion capabilities. The purpose of this book is to provide an overview of the latest wide-range achievements in climbing and walking robotic technology to researchers, scientists, and engineers throughout the world. Different aspects including control simulation, locomotion realization, methodology, and system integration are presented from the scientific and from the technical point of view. This book consists of two main parts, one dealing with walking robots, the second with climbing robots. The content is also grouped by theoretical research and applicative realization. Every chapter offers a considerable amount of interesting and useful information

Climbing and Walking Robots

Nowadays robotics is one of the most dynamic fields of scientific researches. The shift of robotics researches from manufacturing to services applications is clear. During the last decades interest in studying climbing and walking robots has been increased. This increasing interest has been in many areas that most important ones of them are: mechanics, electronics, medical engineering, cybernetics, controls, and computers. Today’s climbing and walking robots are a combination of manipulative, perceptive, communicative, and cognitive abilities and they are capable of performing many tasks in industrial and non- industrial environments. Surveillance, planetary exploration, emergence rescue operations, reconnaissance, petrochemical applications, construction, entertainment, personal services, intervention in severe environments, transportation, medical and etc are some applications from a very diverse application fields of climbing and walking robots. By great progress in this area of robotics it is anticipated that next generation climbing and walking robots will enhance lives and will change the way the human works, thinks and makes decisions. This book presents the state of the art achievments, recent developments, applications and future challenges of climbing and walking robots. These are presented in 24 chapters by authors throughtot the world The book serves as a reference especially for the researchers who are interested in mobile robots. It also is useful for industrial engineers and graduate students in advanced study

Locomotion system for ground mobile robots in uneven and unstructured environments

One of the technology domains with the greatest growth rates nowadays is service robots. The extensive use of ground mobile robots in environments that are unstructured or structured for humans is a promising challenge for the coming years, even though Automated Guided Vehicles (AGV) moving on flat and compact grounds are already commercially available and widely utilized to move components and products inside indoor industrial buildings. Agriculture, planetary exploration, military operations, demining, intervention in case of terrorist attacks, surveillance, and reconnaissance in hazardous conditions are important application domains. Due to the fact that it integrates the disciplines of locomotion, vision, cognition, and navigation, the design of a ground mobile robot is extremely interdisciplinary. In terms of mechanics, ground mobile robots, with the exception of those designed for particular surroundings and surfaces (such as slithering or sticky robots), can move on wheels (W), legs (L), tracks (T), or hybrids of these concepts (LW, LT, WT, LWT). In terms of maximum speed, obstacle crossing ability, step/stair climbing ability, slope climbing ability, walking capability on soft terrain, walking capability on uneven terrain, energy efficiency, mechanical complexity, control complexity, and technology readiness, a systematic comparison of these locomotion systems is provided in [1]. Based on the above-mentioned classification, in this thesis, we first introduce a small-scale hybrid locomotion robot for surveillance and inspection, WheTLHLoc, with two tracks, two revolving legs, two active wheels, and two passive omni wheels. The robot can move in several different ways, including using wheels on the flat, compact ground,[1] tracks on soft, yielding terrain, and a combination of tracks, legs, and wheels to navigate obstacles. In particular, static stability and non-slipping characteristics are considered while analyzing the process of climbing steps and stairs. The experimental test on the first prototype has proven the planned climbing maneuver’s efficacy and the WheTLHLoc robot's operational flexibility. Later we present another development of WheTLHLoc and introduce WheTLHLoc 2.0 with newly designed legs, enabling the robot to deal with bigger obstacles. Subsequently, a single-track bio-inspired ground mobile robot's conceptual and embodiment designs are presented. This robot is called SnakeTrack. It is designed for surveillance and inspection activities in unstructured environments with constrained areas. The vertebral column has two end modules and a variable number of vertebrae linked by compliant joints, and the surrounding track is its essential component. Four motors drive the robot: two control the track motion and two regulate the lateral flexion of the vertebral column for steering. The compliant joints enable limited passive torsion and retroflection of the vertebral column, which the robot can use to adapt to uneven terrain and increase traction. Eventually, the new version of SnakeTrack, called 'Porcospino', is introduced with the aim of allowing the robot to move in a wider variety of terrains. The novelty of this thesis lies in the development and presentation of three novel designs of small-scale mobile robots for surveillance and inspection in unstructured environments, and they employ hybrid locomotion systems that allow them to traverse a variety of terrains, including soft, yielding terrain and high obstacles. This thesis contributes to the field of mobile robotics by introducing new design concepts for hybrid locomotion systems that enable robots to navigate challenging environments. The robots presented in this thesis employ modular designs that allow their lengths to be adapted to suit specific tasks, and they are capable of restoring their correct position after falling over, making them highly adaptable and versatile. Furthermore, this thesis presents a detailed analysis of the robots' capabilities, including their step-climbing and motion planning abilities. In this thesis we also discuss possible refinements for the robots' designs to improve their performance and reliability. Overall, this thesis's contributions lie in the design and development of innovative mobile robots that address the challenges of surveillance and inspection in unstructured environments, and the analysis and evaluation of these robots' capabilities. The research presented in this thesis provides a foundation for further work in this field, and it may be of interest to researchers and practitioners in the areas of robotics, automation, and inspection. As a general note, the first robot, WheTLHLoc, is a hybrid locomotion robot capable of combining tracked locomotion on soft terrains, wheeled locomotion on flat and compact grounds, and high obstacle crossing capability. The second robot, SnakeTrack, is a small-size mono-track robot with a modular structure composed of a vertebral column and a single peripherical track revolving around it. The third robot, Porcospino, is an evolution of SnakeTrack and includes flexible spines on the track modules for improved traction on uneven but firm terrains, and refinements of the shape of the track guidance system. This thesis provides detailed descriptions of the design and prototyping of these robots and presents analytical and experimental results to verify their capabilities

Locomotion and pose estimation in compliant, torque-controlled hexapedal robots

Several scenarios, such as disaster response or terrestrial and extra-terrestrial exploration, comprise environments that are dangerous or even inaccessible for humans. In those cases, autonomous robots pose a promising alternative to render such endeavours possible. While most of today’s robotic explorers are wheeled or tracked vehicles, legged systems gained increased attention in recent years. With their unique combination of omnidirectional mobility and intrinsic manipulation capabilities, they are envisioned to serve as the rough terrain specialists in scouting or sample and return missions. Especially, small to mid-size hexapods are of great interest for those scenarios. Providing static stability across a wide range of walking speeds, they offer an attractive trade-off between versatility and complexity. Another important advantage is their redundancy, allowing them to tolerate the loss of single legs. However, due to their small size, the computational on-board resources are limited. Thus, the use of smart and efficient algorithms is of utmost importance in order to enable autonomous operation within a priori unknown rough environments. Working towards such autonomous robotic scouts, this thesis contributes with the development, implementation, and test of a self-contained walking layer as well as a 6 degrees of freedom (DOF) leg odometry for compliant, torque-controlled, hexapedal robots. Herein, the important property of all presented algorithms is the sole use of proprioceptive measurements provided by the legs, i. e. joint angles and joint torques. Especially the joint torque sensors improve the walking process by enabling the use of sensitive compliance controllers and distributed collision detection. Comprising a set of algorithms, the walking layer organises and structures the walking process in order to generate robust, adaptive, and leg loss tolerant locomotion in uneven terrain. Furthermore, it encapsulates the walking process, and thus hides its complexity from higher-level algorithms such as navigation. Its three main functional components are a flexible, biologically-inspired gait coordination algorithm, single leg reflexes, and active joint compliance control. Thereof, the gait coordination algorithm realises temporal adaptation of the step sequence while reflexes adjust the leg trajectories to the local terrain. The joint compliance control reduces internal forces and allows for situation dependent stiffness adjustments. An algorithmic extensions to the basic gait coordination enables the immediate adaptation to leg loss. In combination with stiffness and pose adjustments, this allows the hexapod to retain stable locomotion on five legs. In order to account for the emerging gait, the leg odometry algorithm employs an optimisation approach to obtain a kinematics-based pose estimate from joint angle measurements. Fusing the resulting pitch and roll angle estimates with joint-torque-measurement-based attitude data, reduces the associated drift, and thus stabilises the overall pose estimate. Various simulations and experiments with the six-legged, torque-controlled DLR Crawler demonstrate the effectiveness of the proposed walking layer as well as the 6-DOF leg odometry.Für die planetare Exploration sowie den Einsatz in Katastrophengebieten sind autonome Laufroboter zunehmend von Interesse. In diesen Szenarien sollen sie den Menschen an gefährlichen oder schwer zugänglichen Orten ersetzen und dort Erkundungseinsätze sowie Probenahmen in schwierigem Gelände durchführen. Unter der Vielzahl an möglichen Systemen bieten im Besonderen kleinere Sechsbeiner einen sehr guten Kompromiss zwischen Stabilität, hoher Beweglichkeit, Vielseitigkeit und einer vertretbaren Komplexität der Regelung. Ein weiterer Vorteil ist ihre Redundanz, die es ihnen erlaubt, den Ausfall einzelner Beine mit geringem Aufwand zu kompensieren. Dementgegen ist die beschränkte Rechenkapazität ein Nachteil der reduzierten Größe. Um diesen auszugleichen und das autonome Agieren in einer unbekannten Umgebung zu ermöglichen, werden daher einfache und effiziente Algorithmen benötigt, die im Zusammenspiel jedoch ein komplexes Verhalten erzeugen. Auf dem Weg zum autonom explorierenden Laufroboter entwickelt diese Arbeit einen robusten, adaptiven und fehlertoleranten Laufalgorithmus sowie eine 6D Eigenbewegungsschätzung für nachgiebige, drehmomentgeregelte Sechsbeiner. Besonders herauszustellen ist, dass alle in der Arbeit vorgestellten Algorithmen ausschließlich die propriozeptive Sensorik der Beine verwenden. Durch diesen Ansatz kann der Laufprozess von anderen Prozessen, wie der Navigation, getrennt und somit der Datenaustausch effizient gestaltet werden. Für die Fortbewegung in unebenem Gelände kombiniert der vorgestellte Laufalgorithmus eine flexible, biologisch inspirierte Gangkoordination mit verschiedenen Einzelbeinreflexen und einer nachgiebigen Gelenkregelung. Hierbei übernimmt die Gangkoordination die zeitliche Steuerung der Schrittfolge, während die Einzelbeinreflexe für eine räumliche Variation der Fußtrajektorien zuständig sind. Die nachgiebige Gelenkregelung reduziert interne Kräfte und erlaubt eine Anpassung der Gelenksteifigkeiten an die lokalen Umgebungsbedingungen sowie den aktuellen Zustand des Roboters. Eine wichtige Eigenschaft des Laufalgorithmus ist seine Fähigkeit, den Ausfall einzelner Beine zu kompensieren. In diesem Fall erfolgt eine Adaption der Gangkoordination über die Erneuerung der Nachbarschaftsbeziehungen der Beine. Zusätzlich verbessern eine Veränderung der Pose und eine Erhöhung der Gelenksteifigkeiten die Stabilität des durch den Beinverlust beeinträchtigten Roboters. Gleich dem Laufalgorithmus verwendet die 6D Eigenbewegungsschätzung nur die Messungen der propriozeptiven Sensoren der Beine. Hierbei arbeitet der Algorithmus in einem dreistufigen Verfahren. Zuerst berechnet er mit Hilfe der Beinkinematik und einer Optimierung die Pose des Roboters. Nachfolgend bestimmt er aus den Gelenkmomentmessungen den Gravitationsvektor und berechnet daraus die Neigungswinkel des Systems. Eine Fusion dieser Werte mit den Nick- und Rollwinkeln der ersten Stufe stabilisiert daraufhin die gesamte Odometrie und reduziert deren Drift. Alle in dieser Arbeit entwickelten Algorithmen wurden mit Hilfe von Simulationen sowie Experimenten mit dem drehmomentgeregelten DLR Krabbler erfolgreich validiert

Development of a Chain Climbing Robot and an Automated Ultrasound Inspection System for Mooring Chain Integrity Assessment

Mooring chains used to stabilise offshore floating platforms are often subjected to harsh environmental conditions on a daily basis, i.e. high tidal waves, storms etc. Chain breakage can lead to vessel drift and serious damage such as riser rupture, production shutdown and hydrocarbon release. Therefore, integrity assessment of chain links is vital, and regular inspection is mandatory for offshore structures. Currently, structural health monitoring of chain links is conducted using either remotely operated vehicles (ROVs), which are associated with high costs, or by manual means, which increases the risk to human operators. The development of climbing robots for mooring chain applications is still in its infancy due to the operational complexity and geometrical features of the chain. This thesis presents a Cartesian legged magnetic adhesion tracked-wheel crawler robot developed for mooring chain inspection. The crawler robot presented in this study is suitable for mooring chain climbing in air and the technique can be adapted for underwater use. The proposed robot addresses straight mooring chain climbing and a misaligned scenario that is commonly evident in in-situ conditions. The robot can be used as a platform to convey equipment, i.e. tools for non-destructive testing/evaluation applications. The application of ultrasound for in-service mooring chain inspection is still in the early stages due to lack of accessibility, in-field operational complexity and the geometrical features of mooring systems. With the advancement of robotic/automated systems (i.e. chain-climbing robotic mechanisms), interest in in-situ ultrasound inspection has increased. Currently, ultrasound inspection is confined to the weld area of the chain links. However, according to recent studies on fatigue and residual stresses, ultrasound inspection of the chain crown should be further investigated. A new automated application for ultrasonic phased-array full-matrix capture is discussed in this thesis for investigation of the chain crown. The concept of the chain-climbing robot and the inspection technique are validated with laboratory-based climbing experiments and presented in this thesis

Marine Vessel Inspection as a Novel Field for Service Robotics: A Contribution to Systems, Control Methods and Semantic Perception Algorithms.

This cumulative thesis introduces a novel field for service robotics: the inspection of marine vessels using mobile inspection robots. In this thesis, three scientific contributions are provided and experimentally verified in the field of marine inspection, but are not limited to this type of application. The inspection scenario is merely a golden thread to combine the cumulative scientific results presented in this thesis. The first contribution is an adaptive, proprioceptive control approach for hybrid leg-wheel robots, such as the robot ASGUARD described in this thesis. The robot is able to deal with rough terrain and stairs, due to the control concept introduced in this thesis. The proposed system is a suitable platform to move inside the cargo holds of bulk carriers and to deliver visual data from inside the hold. Additionally, the proposed system also has stair climbing abilities, allowing the system to move between different decks. The robot adapts its gait pattern dynamically based on proprioceptive data received from the joint motors and based on the pitch and tilt angle of the robot's body during locomotion. The second major contribution of the thesis is an independent ship inspection system, consisting of a magnetic wall climbing robot for bulkhead inspection, a particle filter based localization method, and a spatial content management system (SCMS) for spatial inspection data representation and organization. The system described in this work was evaluated in several laboratory experiments and field trials on two different marine vessels in close collaboration with ship surveyors. The third scientific contribution of the thesis is a novel approach to structural classification using semantic perception approaches. By these methods, a structured environment can be semantically annotated, based on the spatial relationships between spatial entities and spatial features. This method was verified in the domain of indoor perception (logistics and household environment), for soil sample classification, and for the classification of the structural parts of a marine vessel. The proposed method allows the description of the structural parts of a cargo hold in order to localize the inspection robot or any detected damage. The algorithms proposed in this thesis are based on unorganized 3D point clouds, generated by a LIDAR within a ship's cargo hold. Two different semantic perception methods are proposed in this thesis. One approach is based on probabilistic constraint networks; the second approach is based on Fuzzy Description Logic and spatial reasoning using a spatial ontology about the environment

Lunar Excursion Module Familiarization Manual

No abstract availabl

Consider the robot - Abstraction of bioinspired leg coordination and its application to a hexapod robot under consideration of technical constraints

Paskarbeit J. Consider the robot - Abstraction of bioinspired leg coordination and its application to a hexapod robot under consideration of technical constraints. Bielefeld: Universität Bielefeld; 2017.To emulate the movement agility and adaptiveness of stick insects in technical systems such as piezo actuators (Szufnarowski et al. 2014) or hexapod robots (Schneider, Cruse et al. 2006), a direct adaptation of bioinspired walking controllers like WALKNET has often been suggested. However, stick insects have very specific features such as adhesive foot pads that allow them to cling to the ground. Typically, robots do not possess such features. Besides, robots tend to be bigger and heavier than their biological models, usually possessing a different mass distribution as well. This leads to different mechanical and functional properties that need to be addressed in control. Based on the model of the stick insect *Carausius morosus*, the six-legged robot HECTOR was developed in this work to test and evaluate bioinspired controllers. The robot's geometrical layout corresponds to that of the stick insect, scaled up by a factor of 20. Moreover, like the stick insect, the robot features an inherent compliance in its joints. This compliance facilitates walking in uneven terrain since small irregularities can be compensated passively without controller intervention. However, the robot differs from the biological model, e.g., in terms of its size, mass, and mass distribution. Also, it does not possess any means to cling to the ground and therefore must maintain static stability to avoid tilting. To evaluate the ability of stick insects to maintain static stability, experimental data (published by Theunissen et al. (2014)) was examined. It can be shown that stick insects do not maintain static stability at all times. Still, due to their adhesive foot pads, they do not tumble. Therefore, a direct replication of the biological walking controller would not be suitable for the control of HECTOR. In a next step, the bioinspired walking controller WALKNET (Cruse, Kindermann, et al. 1998) was evaluated regarding its applicability for the control of HECTOR. For this purpose, different parametrizations of WALKNET were tested in a simulation environment. For forward walking, parameter sets were found that achieve a high, although not permanent stability. Thus, for the control of HECTOR, which requires continuous stability, a more abstract adaption of the bioinspired coordination had to be found. Based on the original coordination concepts of WALKNET, new coordination mechanisms were developed that incorporate the technical requirements (static stability, angular joint limits, torque constraints, etc.). The ability of the resulting controller to generate insect-like gaits is demonstrated for different walking scenarios in simulation. Moreover, locomotion that is unlikely for insects such as backwards and sidewards walking is shown to be feasible using the novel control approach. At the end of this work the applicability of the approach for the control of the real robot is proved in experiments on visual collision avoidance and basic climbing ability