Design and Analysis of Exaggerated Rectilinear Gait-Based Snake-Inspired Robots

Snake-inspired locomotion is much more maneuverable compared to conventional locomotion concepts and it enables a robot to navigate through rough terrain. A rectilinear gait is quite flexible and has the following benefits: functionality on a wide variety of terrains, enables a highly stable robot platform, and provides pure undulatory motion without passive wheels. These benefits make rectilinear gaits especially suitable for search and rescue applications. However, previous robot designs utilizing rectilinear gaits were slow in speed and required considerable vertical motion. This dissertation will explore the development and implementation of a new exaggerated rectilinear gait that which will enable high speed locomotion and more efficient operation in a snake-inspired robot platform. The exaggerated rectilinear gait will emulate the natural snake's rectilinear gait to gain the benefit a snake's terrain adaptability, but the sequence and range of joint motion will be greatly exaggerated to achieve higher velocities to support robot speeds within the range of human walking speed. The following issues will be investigated in this dissertation. First, this dissertation will address the challenge of developing a snake-inspired robot capable of executing exaggerated rectilinear gaits. To successfully execute the exaggerated rectilinear gait, a snake-inspired robot platform must be able to perform high speed linear expansion/contraction and pivoting motions between segments. In addition to high speed joint motion, the new mechanical architecture much also incorporate a method for providing positive traction during gait execution. Second, a new exaggerated gait dynamics model will be developed using well established kinematics and dynamics analysis techniques. In addition to the exaggerated rectilinear gaits which emphasize high speed, a set of exaggerated rectilinear gaits which emphasize high traction will also be developed for application on difficult terrain types. Finally, an exaggerated rectilinear that emphasizes energy efficiency is defined and analyzed. This dissertation provides the foundations for realizing a high speed limbless locomotion capable of meeting the needs of the search, rescue, and recovery applications

Mechatronic Systems

Mechatronics, the synergistic blend of mechanics, electronics, and computer science, has evolved over the past twenty five years, leading to a novel stage of engineering design. By integrating the best design practices with the most advanced technologies, mechatronics aims at realizing high-quality products, guaranteeing at the same time a substantial reduction of time and costs of manufacturing. Mechatronic systems are manifold and range from machine components, motion generators, and power producing machines to more complex devices, such as robotic systems and transportation vehicles. With its twenty chapters, which collect contributions from many researchers worldwide, this book provides an excellent survey of recent work in the field of mechatronics with applications in various fields, like robotics, medical and assistive technology, human-machine interaction, unmanned vehicles, manufacturing, and education. We would like to thank all the authors who have invested a great deal of time to write such interesting chapters, which we are sure will be valuable to the readers. Chapters 1 to 6 deal with applications of mechatronics for the development of robotic systems. Medical and assistive technologies and human-machine interaction systems are the topic of chapters 7 to 13.Chapters 14 and 15 concern mechatronic systems for autonomous vehicles. Chapters 16-19 deal with mechatronics in manufacturing contexts. Chapter 20 concludes the book, describing a method for the installation of mechatronics education in schools

Dynamic modeling and bioinspired control of a walking piezoelectric motor

Szufnarowski F. Dynamic modeling and bioinspired control of a walking piezoelectric motor. Bielefeld: Universität Bielefeld; 2013.Piezoelectric motors have increasingly extended their field of applications during recent years. Improved material properties and manufacturing techniques have led to a variety of designs which can achieve theoretically unlimited displacements for moderate voltage levels while retaining a relatively high stiffness. In practical terms, this leads to stronger and faster motors which become a viable alternative to electromagnetic drives, especially if compact size and small weight are important. The piezoelectric motor considered in this work consists of four piezoelectric bender elements which can forward a ceramic bar by means of a frictional interaction. The drive elements can be compared to "legs" walking on a movable plane. The walking motor offers outstanding force generation capabilities for a motor of its size. Despite this fact, this motor has not been used in a force control scenario before and no motor models exist in the literature which can reproduce the effect of load on its performance. In this work, two dynamic motor models are developed to address the latter issue. Both of them faithfully reproduce the non-linear motor velocity decrease under load. The first model is based on an analytic approach and describes the low-level frictional interactions between the legs and the ceramic bar by means of several physically meaningful assumptions. This analytic model explains several non-linear phenomena in the operation of the walking motor within the full bandwidth of its rated operation. Non-linear influences due to the impact dynamics of the legs, ferroelectric hysteresis and friction are identified in the motor and new insights for an improved motor design as well as an improved motor-drive strategy gained. Moreover, the analytic model finds its application in a theoretical investigation of an alternative motor-drive strategy which is based on findings in insect walking. Specifically, it is shown that the performance of the motor can be improved by a half in terms of its force generation and doubled in terms of its maximal velocity, as compared to classical drive approaches, if the bioinspired drive strategy as proposed in this work is used. The second model is based on an experimental approach and system identification. Although less general, the second model is well-suited for a practical application in a force-control scenario. In particular, the experimental model is used in this work for the development of a load compensation strategy based on force feedback which restores the linearity of motor operation for moderate levels of loading. Based on the linearized motor model, a force controller is developed whose performance is evaluated both theoretically and experimentally. The developed force controller is also used in a bioinspired control scenario. Specifically, two walking motors together with their force controllers are employed in a 1-DOF antagonistic joint as force generators. The motors are supposed to partially mimic the functionality of a muscle based on the non-linear force-length relation as derived by Hill. A simple positioning task shows the feasibility of this kind of non-standard application of a piezoelectric motor. Beside the development of motor models and bioinspired control approaches, this work addresses the issue of drive-signal generation for the walking motor. Specifically, the development of motor-drive electronics is presented which supersedes the commercially available products due to its compactness and the possibility of waveform generation at much higher drive frequencies, above 50 kHz, as compared to the nominal limit of 3 kHz and commercial products. In this context, the possibility of motor operation at ultrasonic frequencies is discussed which would benefit the motor in terms of its speed and the absence of audible noises

Design, Analysis, and Fabrication of a Snake-Inspired Robot with a Rectilinear Gait

Snake-inspired robots display promise in areas such as search, rescue and reconnaissance due to their ability to locomote through tight spaces. However, several specific issues regarding the design and analysis must be addressed in order to better design them. This thesis develops kinematic and dynamic models for a class of snake-inspired gait known as a rectilinear gait, where mechanism topology changes over the course of the gait. A model using an Eulerian framework and Coulomb friction yields torque expressions for the joints of the robot. B-spline curves are then used to generate a parametric optimization formulation for joint trajectory generation. Exact gradient computation of the torque functions is presented. A parametric model is used to describe the performance effects of changing system parameters such as mass, length, and motor speed. Finally, a snake-inspired robot is designed and fabricated in order to demonstrate both the vertical rectilinear gait and a modular, molded design aimed at reducing the cost of fabrication

Design, Analysis, and Fabrication of a Snake-Inspired Robot with a Rectilinear Gait

Snake-inspired robots display promise in areas such as search, rescue and reconnaissance due to their ability to locomote through tight spaces. However, several specific issues regarding the design and analysis must be addressed in order to better design them. This thesis develops kinematic and dynamic models for a class of snake-inspired gait known as a rectilinear gait, where mechanism topology changes over the course of the gait. A model using an Eulerian framework and Coulomb friction yields torque expressions for the joints of the robot. B-spline curves are then used to generate a parametric optimization formulation for joint trajectory generation. Exact gradient computation of the torque functions is presented. A parametric model is used to describe the performance effects of changing system parameters such as mass, length, and motor speed. Finally, a snake-inspired robot is designed and fabricated in order to demonstrate both the vertical rectilinear gait and a modular, molded design aimed at reducing the cost of fabrication

Engineering Dynamics and Life Sciences

From Preface: This is the fourteenth time when the conference “Dynamical Systems: Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and Ministry of Science and Higher Education of Poland. It is a great pleasure that our invitation has been accepted by recording in the history of our conference number of people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to participate in the conference for the first time. With proud and satisfaction we welcomed over 180 persons from 31 countries all over the world. They decided to share the results of their research and many years experiences in a discipline of dynamical systems by submitting many very interesting papers. This year, the DSTA Conference Proceedings were split into three volumes entitled “Dynamical Systems” with respective subtitles: Vibration, Control and Stability of Dynamical Systems; Mathematical and Numerical Aspects of Dynamical System Analysis and Engineering Dynamics and Life Sciences. Additionally, there will be also published two volumes of Springer Proceedings in Mathematics and Statistics entitled “Dynamical Systems in Theoretical Perspective” and “Dynamical Systems in Applications”

Research and technology, 1990: Goddard Space Flight Center

Goddard celebrates 1990 as a banner year in space based astronomy. From above the Earth's obscuring atmosphere, four major orbiting observatories examined the heavens at wavelengths that spanned the electromagnetic spectrum. In the infrared and microwave, the Cosmic Background Explorer (COBE), measured the spectrum and angular distribution of the cosmic background radiation to extraordinary precision. In the optical and UV, the Hubble Space Telescope has returned spectacular high resolution images and spectra of a wealth of astronomical objects. The Goddard High Resolution Spectrograph has resolved dozens of UV spectral lines which are as yet unidentified because they have never before been seen in any astronomical spectrum. In x rays, the Roentgen Satellite has begun returning equally spectacular images of high energy objects within our own and other galaxies

Zur Mechanik vibrationsgetriebener Roboter für terrestrische und aquatische Lokomotion

This thesis discusses the mechanics of mobile robots for terrestrial and aquatic locomotion. Vibration-driven locomotion systems are characterised by an internal periodic excitation, which is transformed to a directed motion due to asymmetric properties of the system. To perform a two-dimensional and controllable locomotion, mechanical properties of robots are investigated dependent on the frequency of the internal excitation. The mechanical description of the robots is done using analytical and numerical methods and supported by experimental studies. The applicability of the results in mobile robots is proved by prototypes.On the basis of mechanical fundamentals, terrestrial and aquatic locomotion principles are discussed and classified. Actuators are reviewed. The purpose is to evaluate the performance as vibration sources for terrestrial and aquatic systems. Piezoelectric bending elements are particular suitable for it. An extensive overview on the state of the art shows the great potential of vibration-driven locomotion systems for miniaturised applications in technics.Systems with bristles can perform unidirectional terrestrial locomotion. Different working principles of bristles are studied based on a rigid body model and experimental investigations. A prototype for the locomotion in tubes is presented. To perform a controllable two-dimensional locomotion with only one actuator, it is needed to overcome the limits of rigid body systems. The applied approach uses the frequency-dependent vibration behaviour of elastic systems, like beams and plates. Models of continuum mechanics and finite element methods are used and supported by experiments. Based on the investigations, a programmable and remote controlled prototype is developed. The locomotion of it can be controlled on different surfaces by a change of the excitation frequency. The velocity of the prototype is up to 100 mm/s and it can support five times its own weight.Concluding, an innovative prototype with a single piezoelectric actuator for a controllable locomotion on flat ground and floating in fluids is developed. The terrestrial and aquatic locomotion behaviour of the robot is investigated. The carrying capacity of it is calculated using a hydrostatic model.Die Mechanik von mobilen Robotern für terrestrische und aquatische Lokomotion ist der Gegenstand der Arbeit. In den untersuchten Systemen wird die periodische Erregung eines inneren Antriebs durch nicht symmetrische Systemeigenschaften in eine gerichtete Fortbewegung gewandelt. Durch die Nutzung des frequenzabhängigen Schwingungsverhaltens von elastischen Systemen, wie Balken oder Platten, werden Systeme realisiert, die durch nur einen Antrieb eine steuerbare zweidimensionale Lokomotion auf festem Untergrund und an der Oberfläche von Flüssigkeiten durchführen können. Der Schwerpunkt der Arbeit liegt auf der mathematisch-mechanischen Beschreibung der Roboter mittels analytischer und numerischer Methoden sowie ihrer experimentellen Untersuchung. Prototypen mobiler Roboter dienen dem funktionellen Nachweis.Auch im Buchhandel erhältlich: Zur Mechanik vibrationsgetriebener Roboter für terrestrische und aquatische Lokomotion / Felix Becker Ilmenau : Univ.-Verl. Ilmenau, 2015. - XIX, 149 S. ISBN 978-3-86360-124-9 URN urn:nbn:de:gbv:ilm1-2015000338 Preis (Druckausgabe): 21,30