Modeling, Control and Locomotion Planning of an Anguilliform Fish Robot

Ph.DDOCTOR OF PHILOSOPH

生物模倣ソフト魚ロボットの研究開発

In nature, the environment varies from day to day. Through natural selection and competition law of survival of the fittest, the winning creatures survive and their species are able to retain and persist in nature. Based on this fact, creatures existent in nature have their unique features and advantages adapt to the surrounding environment. In recent years, many researches focused on the features of the creatures in nature have been done actively to clarify their morphology and functions and apply the morphology and functions to various fields. Among these researches, the development of the biomimetic robots based on mimicking the creature’s structures and functions has become an active field in robotics recently. In the research, the development of biomimetic robotic fish is focused. So far, there are many researches on biomimetic robotic fish, but improvement on motion performances and efficiency is still an important issue for robot development. Specially, on the biomimetic soft robotic fish utilizing the flexibility of fishes, the developments have been done by the trial and error approach. That is, the design and control method of soft robotic fish has not been established currently. Therefore, it motives us to investigate the design and control of soft robotic fish by numerical simulation that takes into account the interaction between flexible structure and surrounding fluid to develop the biomimetic soft robotic fish with high performance. In order to develop the biomimetic soft robotic fish with high performance, the basic design method and corresponding numerical simulation system are firstly proposed and constructed in this dissertation. Then, based on finite element method (FEM), modelling of soft robotic fish by mimicking the soft structure and driving mechanism of fishes is carried out. The propulsion motion and propulsive force of the soft robotic fish are investigated through two kinds of numerical analyses. One is the modal and transient analysis considering the surrounding fluid as acoustic fluid. The propulsion mode and amplitude of the propulsion motion of soft robotic fish corresponding directly to the propulsion mechanism and motion performance of the robotic fish can be investigated. The other is the fluid-structure interaction (FSI) analysis. The interaction between soft robot structure and surrounding fluid including the dissipation due to fluid viscosity and influence of wake performance around the soft robotic fish are taken into account. From FSI analysis, the hydrodynamic performances of the soft robotic fish can be obtained for investigating its propulsion motion. It is possible to further improve the performance of the soft robotic fish through its design and control based on FSI analysis. Besides, based on coupling analysis by using acoustic fluid, the turning motion control of the soft robotic fish is investigated by its propulsion modes in the fluid. In order to investigate the feasibility of modelling method and numerical simulation analysis on design and control of the biomimetic soft robotic fish, the performance evaluation is carried out by comparison between the simulation and experiment on an actual prototype. Finally, the optimization and improvement are performed for developing the biomimetic soft robotic fish with higher performance based on verified coupling analysis considering the fluid as acoustic fluid, and corresponding performance evaluation on new robot prototype is presented. The performance improvement of the soft robotic fish is confirmed through the new robot prototype. The dissertation consists of six chapters and the main contents are shown as follows. Chapter 1 is an introduction. The background and relative previous work about biomimetic soft robotic fish are briefly reviewed. It summarizes the current research status and problems of biomimetic soft robotic fish, and describes the purposes of this research. Chapter 2 presents the design method, procedures and numerical simulation system in the present research for developing the biomimetic soft robotic fish with high performance. Different from previous development method, our purpose is how to design and control the soft robotic fish by utilizing interaction between the flexible structure and surrounding fluid effectively based on numerical simulations. Therefore, it is necessary to model a fish-like soft robot structure including soft actuators and an enclosed fluid. Besides, by the numerical analysis considering the interaction between flexible structure and fluid, the fish-like propulsion motion should be realized and established, and then the robot structure and control inputs are needed to be optimized for performance improvement. In order to meet these requirements of designing and developing the optimal soft robotic fish, the design method based on modelling, simulation analysis and improvement is presented and the numerical simulation system for soft robotic fish is built. In the simulation system, modelling of soft robotic fish, modal and transient analysis considering the enclosed fluid as acoustic fluid are firstly described based on FEM to realize the fish-like propulsion motion with large amplitude for the soft robotic fish. Then, the FSI analysis is performed to describe and establish the hydrodynamic performances of the soft robotic fish. Based on this numerical simulation system, it is possible to develop the biomimetic soft robotic fish with high performance effectively by optimization of design and control of the soft robotic fish. Chapter 3 describes the modelling and numerical analysis of biomimetic soft robotic fish by using the method presented in Chapter 2. The soft robotic fish uses the piezoelectric fiber composite (PFC) as soft actuator. Firstly, the relationships between the input voltage and generated stress of the PFC are derived. The generated stress can be applied on soft structure to investigate the motion performance of the soft robotic fish. To support the driving model of the PFC, the corresponding experiments on simple beam model are carried out. By comparing the simulation results with experimental results, the effectiveness of the driving model is verified. Then, the modal analysis in which the fluid is considered as acoustic fluid is performed. The structural mode frequencies and mode shapes of the soft robotic fish in the fluid are calculated. By comparing these modes’ motion with those of the real fishes, the fish-like propulsion mode is identified to realize the corresponding propulsion motion of the soft robotic fish. Furthermore, based on the verified driving model of soft actuator, the amplitude of the main propulsion motion of soft robotic fish is calculated. Through FSI analysis, the relationships of driving frequencies of input signal with propulsive force and displacement of propulsion motion, and vortex distribution in the wake around the soft robotic fish are investigated for the case of fixing robot head. Besides, the motion control of soft robot is investigated to realize turning motion in the fluid. Through controlling the input voltage amplitude on soft actuators of the robot, turning right and turning left motion are identified in the swimming when the input voltage amplitudes on two actuators are in asymmetric distribution. Chapter 4 is experiment evaluation. In order to validate the results of numerical simulation analysis described in Chapter 3, the mode shapes, amplitude of propulsion motion, propulsive force and vortex distribution around soft robotic fish for the case of fixing robot head, and turning motion are measured by using actual robot prototype. The present simulation results are congruent with experiments. By the results, the effectiveness of the modelling method and numerical analysis used in the research is verified and they are useful to predict the propulsion characteristics of the soft robotic fish in the fluid for performance improvement. Chapter 5 develops a new soft robotic fish with high performance based on above modelling method and numerical analysis by optimization. Firstly, the structural parameters of the robot are allowed to vary within a range and the amplitude of the propulsion motion for the soft robot is calculated for different parameters by the numerical analysis. Then the structural parameters of the robot capable of propulsion motion with largeramplitude are chosen for improvement. Based on this result, new soft robot is designed and evaluated by experiments. From the experimental results of the new soft robot, it is confirmed that the higher swimming speed, better fish-like swimming performance and larger turning velocity are realized. It can be said that the new soft robotic fish has been developed successfully for improvement. Chapter 6 summarizes the conclusions and future works of this research.電気通信大学201

PROGRAM and PROCEEDINGS THE NEBRASKA ACADEMY OF SCIENCES: 139th Anniversary Year, One Hundred-Twenty-Ninth Annual Meeting, April 12, 2019, NEBRASKA WESLEYAN UNIVERSITY, LINCOLN, NEBRASKA

PROGRAM AT-A-GLANCE FRIDAY, APRIL 12, 2019 7:30 a.m. REGISTRATION OPENS - Lobby of Lecture Wing, Olin Hall 8:00 Aeronautics and Space Science, Session A – Acklie 109 Aeronautics and Space Science, Session B – Acklie 111 Collegiate Academy; Biology, Session B - Olin B Biological and Medical Sciences, Session A - Olin 112 Biological and Medical Sciences, Session B - Smith Callen Conference Center Chemistry and Physics; Chemistry - Olin A 8:00 “Teaching and Learning the Dynamics of Cellular Respiration Using Interactive Computer Simulations” Workshop – Olin 110 9:30 “Life After College: Building Your Resume for the Future” Workshop – Acklie 218 8:25 Collegiate Academy; Chemistry and Physics, Session A – Acklie 007 8:36 Collegiate Academy; Biology, Session A - Olin 111 9:00 Chemistry and Physics; Physics – Acklie 320 9:10 Aeronautics and Space Science, Poster Session – Acklie 109 & 111 10:30 Aeronautics and Space Science, Poster Session – Acklie 109 & 111 11:00 MAIBEN MEMORIAL LECTURE: Dr David Swanson - OLIN B Scholarship and Friend of Science Award announcements 12:00 p.m. LUNCH – WESLEYAN CAFETERIA Round-Table Discussion – “Assessing the Academy: Current Issues and Avenues for Growth” led by Todd Young – Sunflower Room 12:50 Anthropology – Acklie 109 1:00 Applied Science and Technology - Olin 111 Biological and Medical Sciences, Session C - Olin 112 Biological and Medical Sciences, Session D - Smith Callen Conference Center Chemistry and Physics; Chemistry - Olin A Collegiate Academy; Biology, Session B - Olin B Earth Science – Acklie 007 Environmental Sciences – Acklie 111 Teaching of Science and Math – Acklie 218 1:20 Chemistry and Physics; Physics – Acklie 320 4:30 BUSINESS MEETING - OLIN B NEBRASKA ASSOCIATION OF TEACHERS OF SCIENCE (NATS) The 2019 Fall Conference of the Nebraska Association of Teachers of Science (NATS) will be held at the Younes Conference Center, Kearney, NE, September 19-21, 2019. President: Betsy Barent, Norris Public Schools, Firth, NE President-Elect: Anya Covarrubias, Grand Island Public Schools, Grand Island, NE AFFILIATED SOCIETIES OF THE NEBRASKA ACADEMY OF SCIENCES, INC. 1. American Association of Physics Teachers, Nebraska Section Web site: http://www.aapt.org/sections/officers.cfm?section=Nebraska 2. Friends of Loren Eiseley Web site: http://www.eiseley.org/ 3. Lincoln Gem & Mineral Club Web site: http://www.lincolngemmineralclub.org/ 4. Nebraska Chapter, National Council for Geographic Education 5. Nebraska Geological Society Web site: http://www.nebraskageologicalsociety.org Sponsors of a $50 award to the outstanding student paper presented at the Nebraska Academy of Sciences Annual Meeting, Earth Science /Nebraska Chapter, Nat\u27l Council Sections 6. Nebraska Graduate Women in Science 7. Nebraska Junior Academy of Sciences Web site: http://www.nebraskajunioracademyofsciences.org/ 8. Nebraska Ornithologists’ Union Web site: http://www.noubirds.org/ 9. Nebraska Psychological Association http://www.nebpsych.org/ 10. Nebraska-Southeast South Dakota Section Mathematical Association of America Web site: http://sections.maa.org/nesesd/ 11. Nebraska Space Grant Consortium Web site: http://www.ne.spacegrant.org

Advanced Energy Harvesting Technologies

Energy harvesting is the conversion of unused or wasted energy in the ambient environment into useful electrical energy. It can be used to power small electronic systems such as wireless sensors and is beginning to enable the widespread and maintenance-free deployment of Internet of Things (IoT) technology. This Special Issue is a collection of the latest developments in both fundamental research and system-level integration. This Special Issue features two review papers, covering two of the hottest research topics in the area of energy harvesting: 3D-printed energy harvesting and triboelectric nanogenerators (TENGs). These papers provide a comprehensive survey of their respective research area, highlight the advantages of the technologies and point out challenges in future development. They are must-read papers for those who are active in these areas. This Special Issue also includes ten research papers covering a wide range of energy-harvesting techniques, including electromagnetic and piezoelectric wideband vibration, wind, current-carrying conductors, thermoelectric and solar energy harvesting, etc. Not only are the foundations of these novel energy-harvesting techniques investigated, but the numerical models, power-conditioning circuitry and real-world applications of these novel energy harvesting techniques are also presented