30 research outputs found

    Design and Experimental Evaluation of a Hybrid Wheeled-Leg Exploration Rover in the Context of Multi-Robot Systems

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    With this dissertation, the electromechanic design, implementation, locomotion control, and experimental evaluation of a novel type of hybrid wheeled-leg exploration rover are presented. The actively articulated suspension system of the rover is the basis for advanced locomotive capabilities of a mobile exploration robot. The developed locomotion control system abstracts the complex kinematics of the suspension system and provides platform control inputs usable by autonomous behaviors or human remote control. Design and control of the suspension system as well as experimentation with the resulting rover are in the focus of this thesis. The rover is part of a heterogeneous modular multi-robot exploration system with an aspired sample return mission to the lunar south pole or currently hard-to-access regions on Mars. The multi-robot system pursues a modular and reconfigurable design methodology. It combines heterogeneous robots with different locomotion capabilities for enhanced overall performance. Consequently, the design of the multi-robot system is presented as the frame of the rover developments. The requirements for the rover design originating from the deployment in a modular multi-robot system are accentuated and summarized in this thesis

    Development of a Mobile Modular Robotic System, R2TM3, for Enhanced Mobility in Unstructured Environments

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    Limited mobility of mobile ground robots in highly unstructured environments is a problem that inhibits the use of such robots in applications with irregular terrain. Furthermore, applications with hazardous environments are good candidates for the use of robotics to reduce the risk of harm to people. Urban search and rescue (USAR) is an application where the environment is irregular, highly unstructured and hazardous to rescuers and survivors. Consequently, it is of interest to effectively use ground robots in applications such as USAR, by employing mobility enhancement techniques, which stem from the robot’s mechanical design. In this case, a robot may go over an obstacle rather than around it. In this thesis the Reconfigurable Robot Team of Mobile Modules with Manipulators (R2TM3) is proposed as a solution to limited mobility in unstructured terrains, specifically aimed at USAR. In this work the conceptualization, mechatronic development, controls, implementation and testing of the system are given. The R2TM3 employs a mobile modular system in which each module is highly functional: self mobile and capable of manipulation with a five degree of freedom (5-DOF) serial manipulator. The manipulator configuration, the docking system and cooperative strategy between the manipulators and track drives enable a system that can perform severe obstacle climbing and also remain highly manoeuvrable. By utilizing modularity, the system may emulate that of a larger robot when the modules are docking to climb obstacles, but may also get into smaller confined spaces by using single robot modules. The use of the 5-DOF manipulator as the docking device allows for module docking that can cope with severe misalignments and offsets – a critical first step in cooperative obstacle management in rough terrain. The system’s concept rationale is outlined, which has been formulated based on a literature review of mobility enhanced systems. Based on the concept, the realization of a low cost prototype is described in detail. Single robot and cooperative robot control methods are given and implemented. Finally, a variety of experiments are conducted with the concept prototype which shows that the intended performance of the concept has been met: mobility enhancement and manoeuvrability

    An Overview of Legged Robots

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    The objective of this paper is to present the evolution and the state-of-theart in the area of legged locomotion systems. In a first phase different possibilities for mobile robots are discussed, namely the case of artificial legged locomotion systems, while emphasizing their advantages and limitations. In a second phase an historical overview of the evolution of these systems is presented, bearing in mind several particular cases often considered as milestones on the technological and scientific progress. After this historical timeline, some of the present day systems are examined and their performance is analyzed. In a third phase are pointed out the major areas for research and development that are presently being followed in the construction of legged robots. Finally, some of the problems still unsolved, that remain defying robotics research, are also addressed.N/

    Locomotion system for ground mobile robots in uneven and unstructured environments

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    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

    Climbing and Walking Robots

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    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

    Navegación de un robot móvil sobre terreno irregular con contacto de su brazo con el suelo

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    En esta tesis se aborda el problema de la navegabilidad de robots móviles sobre terrenos irregulares, los cuales poseen diferentes inclinaciones y variedad de obstáculos. Este tema constituye actualmente una línea de investigación activa dirigida al desarrollo de nuevos robots y, adicionalmente, enfocada al desarrollo de estrategias de navegación eficientes y con el mínimo riesgo de inutilización. En primer lugar se desarrolló el robot móvil Lázaro para navegar en este tipo de terrenos, el cual posee un brazo articulado con una rueda como efector final. Esta rueda le permite al brazo mantener un punto de contacto adicional con el suelo que puede ayudar al robot a compensar situaciones de inestabilidad y sobrepasar algunos obstáculos que pudieran presentarse en estos entornos. Posteriormente, se desarrollaron tres medidas cuantitativas que permiten evaluar la navegabilidad de cualquier robot móvil cuando transita sobre terreno irregular. Estas tres medidas son: un índice de estabilidad, el cual evalúa la propensión al vuelco; un índice de direccionamiento, el cual evalúa la disponibilidad del robot para direccionarse y seguir una trayectoria dada y, por último, un índice de deslizamiento, el cual evalúa la propensión del robot a deslizarse hacia abajo cuando se desplaza sobre superficies inclinadas. Finalmente, se definieron un conjunto de maniobras que puede ejecutar Lázaro y que están dirigidas a garantizar la navegación cuando el robot se desplaza sobre superficies inclinadas o cuando debe sobrepasar obstáculos tales como escalones, rampas o zanjas. Todas las estrategias diseñadas se fundamentan en el uso del brazo como herramienta adicional que posee el robot para mejorar su navegabilidad

    Modeling and control of a robot manipulator

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    Includes bibliographical references.This thesis presents work completed on the design of the modelling and path planning components for a robot manipulator mounted on a mobile platform. This platform is for use in the mining safety inspections of the mine roof, i.e., the hanging wall. Currently this process is done by mine workers and it places them at risk of falling of unstable rocks from the roof. A geometric based inverse kinematics algorithm for a 5 DOF redundant manipulator is proposed and implemented on a Packbot510i used as a test platform. Three versions of the Rapidly-exploring Random Trees planning algorithm namely, basic RRT, RRT Ball and RRT_ are compared. Results obtained show that RRT_ is more suitable than RRT and RRT Ball in terms of the length and the consistency of the trajectories produced. A Force Angle stability measure is used to guide the robot arm into trajectories that prevent the robotic system from tipping over. Results show that the Force Angle stable measure is more cautious, i.e., it classifies trajectories close to the instability of the system as unstable. Simulation results provided show that this system is capable of carrying out the safety inspections of the roof in the mining environment. Experimental results show that a few modifications are required for the system to be used practically on the test platform due to issues experienced with the hardware

    Analytical Workspace, Kinematics, and Foot Force Based Stability of Hexapod Walking Robots

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    Many environments are inaccessible or hazardous for humans. Remaining debris after earthquake and fire, ship hulls, bridge installations, and oil rigs are some examples. For these environments, major effort is being placed into replacing humans with robots for manipulation purposes such as search and rescue, inspection, repair, and maintenance. Mobility, manipulability, and stability are the basic needs for a robot to traverse, maneuver, and manipulate in such irregular and highly obstructed terrain. Hexapod walking robots are as a salient solution because of their extra degrees of mobility, compared to mobile wheeled robots. However, it is essential for any multi-legged walking robot to maintain its stability over the terrain or under external stimuli. For manipulation purposes, the robot must also have a sufficient workspace to satisfy the required manipulability. Therefore, analysis of both workspace and stability becomes very important. An accurate and concise inverse kinematic solution for multi-legged robots is developed and validated. The closed-form solution of lateral and spatial reachable workspace of axially symmetric hexapod walking robots are derived and validated through simulation which aid in the design and optimization of the robot parameters and workspace. To control the stability of the robot, a novel stability margin based on the normal contact forces of the robot is developed and then modified to account for the geometrical and physical attributes of the robot. The margin and its modified version are validated by comparison with a widely known stability criterion through simulated and physical experiments. A control scheme is developed to integrate the workspace and stability of multi-legged walking robots resulting in a bio-inspired reactive control strategy which is validated experimentally

    Design and Development of Assistive Robots for Close Interaction with People with Disabilities

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    People with mobility and manipulation impairments wish to live and perform tasks as independently as possible; however, for many tasks, compensatory technology does not exist, to do so. Assistive robots have the potential to address this need. This work describes various aspects of the development of three novel assistive robots: the Personal Mobility and Manipulation Appliance (PerMMA), the Robotic Assisted Transfer Device (RATD), and the Mobility Enhancement Robotic Wheelchair (MEBot). PerMMA integrates mobility with advanced bi-manual manipulation to assist people with both upper and lower extremity impairments. The RATD is a wheelchair mounted robotic arm that can lift higher payloads and its primary aim is to assist caregivers of people who cannot independently transfer from their electric powered wheelchair to other surfaces such as a shower bench or toilet. MEBot is a wheeled robot that has highly reconfigurable kinematics, which allow it to negotiate challenging terrain, such as steep ramps, gravel, or stairs. A risk analysis was performed on all three robots which included a Fault Tree Analysis (FTA) and a Failure Mode Effect Analysis (FMEA) to identify potential risks and inform strategies to mitigate them. Identified risks or PerMMA include dropping sharp or hot objects. Critical risks identified for RATD included tip over, crush hazard, and getting stranded mid-transfer, and risks for MEBot include getting stranded on obstacles and tip over. Lastly, several critical factors, such as early involvement of people with disabilities, to guide future assistive robot design are presented
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