The development and implementation of an ionic-polymer-metal-composite propelled vessel guided by a goal-seeking algorithm

This thesis describes the use of an ultrasonic goal-seeking algorithm while using ionic polymer metal composite (IPMC), an electroactive polymer, as the actuator to drive a vessel towards a goal. The signal transmitting and receiving circuits as well as the goal seeking algorithm are described in detail. Two test vessels were created; one was a larger vessel that contained all necessary components for autonomy. The second was a smaller vessel that contained only the sensors and IPMC strips, and all power and signals were transmitted via an umbilical cord. To increase the propulsive efforts of the second, smaller vessel, fins were added to the IPMC strips, increasing the surface area over 700%, determined to yield a 22-fold force increase. After extensive testing, it was found that the three IPMC strips, used as oscillating fins, could not generate enough propulsion to move either vessel, with or without fins. With the addition of fins, the oscillating frequency was reduced from 0.86-Hz to 0.25-Hz. However, the goal-seeking algorithm was successful in guiding the vessel towards the target, an ultrasonic transmitter. When moved manually according to the instructions given by the algorithm, the vessel successfully reached the goal. Using assumptions based on prior experiments regarding the speed of an IPMC propelled vessel, the trial in which the goal was to the left of the axis required 18.2% more time to arrive at the goal than the trial in which the goal was to the right. This significant difference is due to the goal-seeking algorithmâÂÂs means to acquire the strongest signal. After the research had concluded and the propulsors failed to yield desired results, many factors were considered to rationalize the observations. The operating frequency was reduced, and it was found that, by the impulse-momentum theorem, that the propulsive force was reduced proportionally. The literature surveyed addressed undulatory motion, which produces constant propulsive force, not oscillatory, which yields intermittent propulsive force. These reasons among others were produced to rationalize the results and prove the cause of negative results was inherent to the actuators themselves. All rational options have been considered to yield positive results

Novel Configurations of Ionic Polymer-Metal Composites (IPMCs) As Sensors, Actuators, and Energy Harvesters

This dissertation starts with describing the IPMC and defining its chemical structure and fundamental characteristics in Chapter 1. The application of these materials in the form of actuator, sensor, and energy harvester are reported through a literature review in Chapter 2. The literature review involves some electromechanical modeling approaches toward physics of the IPMC as well as some of the experimental results and test reports. This chapter also includes a short description of the manufacturing process of the IPMC. Chapter 3 presents the mechanical modeling of IPMC in actuation. For modeling, shear deformation expected not to be significant. Hence, the Euler-Bernoulli beam theory considered to be the approach defining the shape and critical points of the proposed IPMC elements. Description of modeling of IPMC in sensing mode is in Chapter 4. Since the material undergoes large deformation, large beam deformation is considered for both actuation and sensing model. Basic configurations of IPMC as sensor and actuator are introduced in Chapter 5. These basic configurations, based on a systematic approach, generate a large number of possible configurations. Based on the presented mechanisms, some parameters can be defined, but the selection of a proper arrangement remained as an unknown parameter. This mater is addressed by introducing a decision-making algorithm. A series of design for slit cylindrical/tubular/helical IPMC actuators and sensors are introduced in chapter 5. A consideration related to twisting of IPMCs in helical formations is reported through some experiments. Combinations of these IPMC actuators and sensors can be made to make biomimetic robotic devices as some of them are discussed in this chapter and the following Chapters 6 and 7. Another set of IPMC actuator/sensor configurations are introduced as a loop sensor and actuator that are presented subsequently in Chapter 6. These configurations may serve as haptic and tactile feedback sensors, particularly for robotic surgery. Both of these configurations (loop and slit cylindrical) of IPMCs are discussed in details, and some experimental measurements and results are also carried out and reported. The model for different inputs is studied, and report of the feedback is presented. Various designs of these configurations of IPMC are also presented in chapter 7, including their extension to mechanical metamaterials and soft robots

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