Design Issues for Hexapod Walking Robots

Hexapod walking robots have attracted considerable attention for several decades. Many studies have been carried out in research centers, universities and industries. However, only in the recent past have efficient walking machines been conceived, designed and built with performances that can be suitable for practical applications. This paper gives an overview of the state of the art on hexapod walking robots by referring both to the early design solutions and the most recent achievements. Careful attention is given to the main design issues and constraints that influence the technical feasibility and operation performance. A design procedure is outlined in order to systematically design a hexapod walking robot. In particular, the proposed design procedure takes into account the main features, such as mechanical structure and leg configuration, actuating and driving systems, payload, motion conditions, and walking gait. A case study is described in order to show the effectiveness and feasibility of the proposed design procedure

Nautilus ROV Robot Manipulator

Global warming and climate change are prevalent issues in today’s society. As a result, research in the ocean, our world’s biggest ecosystem, is imperative in efforts to protect the environment. Santa Clara University’s Robotic Systems Lab contributes to this field through work and developments on remotely operated vehicles (ROVs). An existing ROV system called Nautilus consists of a robot arm, end effector, and storage system in order to collect various types of sediments at a depth of 300 feet. However, the previous system does not meet that requirement. In direct collaboration with researchers within the Monterey Bay Aquarium Research Institute, we were able to create and accomplish a set of deliverables to improve our ROV. Our team’s main goal was to make the system functional and more efficient by redesigning the manipulator arm and soft gripper in order to retrieve samples, as well as creating a sample storage container that is in view of the camera or workspace to document and record the location of those samples. Our project gives researchers a cheaper alternative compared to existing sample collection methods, which are relatively more expensive, so that they can continue to explore and document stretches of the ocean far more easily. The project was done with the guidance of faculty in the Robotic Systems Lab as well as researchers from the Monterey Bay Aquarium Research Institute (MBARI)

Position / force control of systems subjected to communicaton delays and interruptions in bilateral teleoperation

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2012Includes bibliographical references (leaves: 65-68)Text in English; Abstract: Turkish and Englishix, 76 leavesTeleoperation technology allows to remotely operate robotic (slave) systems located in hazardous, risky and distant environments. The human operator sends commands through the controller (master) system to execute the tasks from a distance. The operator is provided with necessary (visual, audio or haptic) feedback to accomplish the mission remotely. In bilateral teleoperation, continuous feedback from the remote environment is generated. Thus, the operator can handle the task as if the operator is in the remote environment relying on the relevant feedback. Since teleoperation deals with systems controlled from a distance, time delays and package losses in transmission of information are present. These communication failures affect the human perception and system stability, and thus, the ability of operator to handle the task successfully. The objective of this thesis is to investigate and develop a control algorithm, which utilizes model mediated teleoperation integrating parallel position/force controllers, to compensate for the instability issues and excessive forcing applied to the environment arising from communication failures. Model mediation technique is extended for three-degrees-of-freedom teleoperation and a parallel position/force controller, impedance controller, is integrated in the control algorithm. The proposed control method is experimentally tested by using Matlab Simulink blocksets for real-time experimentation in which haptic desktop devices, Novint Falcon and Phantom Desktop are configured as master and slave subsystems of the bilateral teleoperation. The results of these tests indicate that the stability and passivity of proposed bilateral teleoperation systems are preserved during constant and variable time delays and data losses while the position and force tracking test results provide acceptable performance with bounded errors

Developing Intuitive, Closed-Loop, Teleoperative Control of Continuum Robotic Systems

This thesis presents a series of related new results in the area of continuum robot teleoperation and control. A new nonlinear control strategy for the teleoperation of extensible continuum robots is described. Previous attempts at controlling continuum robots have proven difficult due to the complexity of their system dynamics. Taking advantage of a previously developed dynamic model for a three-section, planar, continuum manipulator, we present an adaptation control-inspired law. Simulation and experimental results of a teleoperation scheme between a master device and an extensible continuum slave manipulator using the new controller are presented. Two novel user interface approaches to the teleoperation of continuum robots are also presented. In the first, mappings from a six Degree-of-Freedom (DoF) rigid-link robotic arm to a nine degree-of-freedom continuum robot are synthesized, analyzed, and implemented, focusing on their potential for creating an intuitive operational interface. Tests were conducted across a range of planar and spatial tasks, using fifteen participant operators. The results demonstrate the feasibility of the approach, and suggest that it can be effective independent of the prior robotics, gaming, or teleoperative experience of the operator. In the second teleoperation approach, a novel nine degree-of-freedom input device for the teleoperation of extensible continuum robots is introduced. As opposed to previous works limited by kinematically dissimilar master devices or restricted degrees-of-freedom, the device is capable of achieving configurations identical to a three section continuum robot, and simplifying the control of such manipulators. The thesis discusses the design of the control device and its construction. The implementation of the new master device is discussed and the effectiveness of the system is reported

Modeling of an Autonomous Underwater Vehicle

Autonomous Underwater Vehicles (AUV) have multiple applications for military, commercial and research purposes. The main advantage of this technology is its independence. Since these vehicles operate autonomously, the need for a dedicated support vessel and human supervision is dismissed. However, the autonomous nature of AUVs also presents a complex challenge for the guidance, navigation and control system(s). The design of motion controllers for AUVs is model-based i.e. a dynamic model is used for the design of the control system. The dynamic model can also be used for simulation and performance analysis. In this context, the purpose of this thesis is to provide a dynamic model for a double-body research AUV being developed at CEiiA. This model is to be subsequently used for the design of the control system. Since the purpose is the design of the control system and, in the scope of providing multiple design approaches, the appropriate lateral and longitudinal subsystems are devised. These subsystems are subsequently validated by comparing simulation results for the subsystems with simulation results for the complete model. The AUV is modeled using Fossen’s dynamic model. The model is divided into kinematics and kinetics. Kinematics addresses the geometrical aspects of motion. For this purpose, both Euler angles and quaternions are used. Kinetics focuses on the relationship between motion and force. This model identifies four distinct forces that act on the underwater vehicle: rigid-body forces; hydrostatic forces; hydrosynamic damping (or drag) and added-mass. The estimation of model parameters is performed using analytical and computational methods. A detailed 3D CAD model, developed by CEiiA, proved helpful for estimating mass and inertia parameters as well as hydrostatic forces. Hydrodynamic damping estimation was performed by adapting CFD analysis, also developed by CEiiA, to satisfy model parameters. Added mass parameters were estimated using proven analytical methods. Due to limitations inherent to current modeling methods, simplifications were unavoidable. These, when analyzed considering the requirements of typical control systems, did not pose an impediment to the use of the dynamic model for this purpose. Regarding the dynamics of this AUV, the hydrodynamic analysis suggests that this AUV is unstable in the presence of angles of attack and side-slip. However the AUV’s motors should be capable of controlling such instabilities.Os veículos subaquáticos autónomos (Autonomous Underwater Vehicles – AUV’s) têm múltiplas aplicações militares, comerciais e para investigação científica. A grande vantagem destes veículos advém da sua independência, sendo que operam sem a necessidade de supervisão humana. No entanto esta capacidade implica que os sistemas de navegação, guia e controlo sejam completamente responsáveis pelo governo do veículo. O sistema de controlo destes veículos é tipicamente projetado tendo como base um modelo dinâmico do mesmo. Este modelo pode ser também usado para simulação e análise de desempenho. O propósito deste trabalho é desenvolver um modelo dinâmico para um AUV de investigação de duplo-corpo, a ser desenvolvido no CEiiA. Dado que o objetivo principal do modelo é projetar controladores e, de modo a fornecer várias abordagens para o efeito, os respetivos modelos (subsistemas) lateral e longitudinal são deduzidos. Estes modelos são posteriormente validados através da comparação de resultados de simulação para os subsistemas com os resultados de simulação para o modelo completo. A modelação deste veículo é efetuada usando o modelo dinâmico de Fossen. Este modelo pode ser dividido em cinemática e cinética. Cinemática aborda os aspetos geométricos do movimento. As equações de cinemática são fornecidas tanto para ângulos de Euler como para quaterniões. As equações de cinética centram-se na relação entre movimento e força. O modelo de Fossen identifica quatro forças distintas que influenciam a dinâmica dos veículos subaquáticos: forças de corpo rígido; forças hidrostáticas; amortecimento (atrito) hidrodinâmico e added mass. Estas forças são modeladas através de métodos analíticos e computacionais. O modelo CAD do veículo, desenvolvido pelo CEiiA, foi usado para estimar os parâmetros de massa e inércia, bem como forças hidrostáticas. O amortecimento hidrodinâmico foi estimado através da adaptação de análises CFD, também efetuadas pelo CEiiA, para satisfazer os parâmetros do modelo. Os parâmetros added mass foram estimados usando métodos analíticos comprovados. Devido a limitações inerentes aos métodos de modelação atuais, simplificações foram inevitáveis. As mesmas, quando analisadas tendo em conta os requisitos de sistemas de controlo típicos não provaram ser impeditivas da aplicação deste modelo para o desenvolvimento dos mesmos. No que diz respeito à dinâmica deste AUV, a análise hidrodinâmica sugere que este AUV é instável quando na presença de ângulos de ataque e derrapagem. No entanto os motores do AUV deverão ser capazes de corrigir tais instabilidades

Robotics for High School Students in a University Environment

The Young Scholars Program at the Institute for Systems Research of theUniversity of Maryland at College Park is an innovative summer researchexperience for high school students from Maryland, Virginia, and WashingtonD.C. Its goal is to steer talented high school seniors toward higher educationand careers in science and engineering.One particularly popular component ofthis program is a two-week mini-course in robotics. This course utilizes theresources of the Intelligent Servosystems Laboratory of the university tointroduce and demonstrate theoretical and practical aspects of robotics. Thispaper reports on the characteristics that make this a unique effort inrobotics-related education for both the Young Scholars Program participantsand the small group of University of Maryland graduate students who have beenresponsible for the development and instruction of this course.The content of this material has been published in theComputer Science Education Journal, vol. 7, no. 2, 1996, 257-278.</CENTER

Bio-Inspired Robotics

Modern robotic technologies have enabled robots to operate in a variety of unstructured and dynamically-changing environments, in addition to traditional structured environments. Robots have, thus, become an important element in our everyday lives. One key approach to develop such intelligent and autonomous robots is to draw inspiration from biological systems. Biological structure, mechanisms, and underlying principles have the potential to provide new ideas to support the improvement of conventional robotic designs and control. Such biological principles usually originate from animal or even plant models, for robots, which can sense, think, walk, swim, crawl, jump or even fly. Thus, it is believed that these bio-inspired methods are becoming increasingly important in the face of complex applications. Bio-inspired robotics is leading to the study of innovative structures and computing with sensory–motor coordination and learning to achieve intelligence, flexibility, stability, and adaptation for emergent robotic applications, such as manipulation, learning, and control. This Special Issue invites original papers of innovative ideas and concepts, new discoveries and improvements, and novel applications and business models relevant to the selected topics of ``Bio-Inspired Robotics''. Bio-Inspired Robotics is a broad topic and an ongoing expanding field. This Special Issue collates 30 papers that address some of the important challenges and opportunities in this broad and expanding field

The dynamic modelling and development of a controller for a general purpose remotely operated underwater vehicle

A preliminary mathematical model for the UCT SEAHOG Remotely operated underwater vehicle (ROV) is developed, including estimation of the rigid body, hydrodynamic and hydrostatic properties of the robot. A single state thruster model is developed and verified according to real life test data. A closed-loop speed controller is developed for the thruster module using a standard PI scheme and is implemented on an MSP430 microcontroller using software fixed-point algorithms. The complete ROV system is simulated in Simulink® in an open-loop configuration to gain insight into the expected motion from the vehicle. Controllers for depth and heading holding are designed using standard PID linearized control methods with gain scheduling and are then assessed within the complete system in a simulation environment. In addition, upgrades and maintenance are performed on the Power Pod, light and camera modules. Redesign, manufacture and testing of the SEAHOG junction box is performed, including a design solution to connect the tether power and fibre-optic lines at the surface and on the ROV. An extensive overhaul of the SEAHOG GUI is performed, utilising multicore processing architecture in LabVIEW and resulting in a user-orientated interface capable of controlling and monitoring all existing system data from the robot