3D locomotion biomimetic robot fish with haptic feedback

This thesis developed a biomimetic robot fish and built a novel haptic robot fish system based on the kinematic modelling and three-dimentional computational fluid dynamic (CFD) hydrodynamic analysis. The most important contribution is the successful CFD simulation of the robot fish, supporting users in understanding the hydrodynamic properties around it

Development of Subcarangiform Bionic Robotic Fish Propelled by Shape Memory Alloy Actuators

In this paper, a shape memory alloy (SMA) actuated subcarangiform robotic fish has been demonstrated using a spring based propulsion mechanism. The bionic robotic fish developed using SMA spring actuators and light weight 3D printed components can be employed for under water applications. The proposed SMA spring-based design without conventional motor and other rotary actuators was able to achieve two-way shape memory effect and has reproduced the subcarangiform locomotion pattern. The positional kinematic model has been developed and the dynamics of the proposed mechanism were analysed and simulated using Automated Dynamic Analysis of Mechanical Systems (ADAMS). An open loop Arduino-relay based switching control has been adopted to control the periodic actuation of the SMA spring mechanism. The undulation of caudal fin in air and water medium has been analysed. The caudal fin and posterior body of the developed fish prototype have taken part in undulation resembling subcarangiform locomotion pattern and steady swimming was achieved in water with a forward velocity of 24.5 mm/s. The proposed design is scalable, light weight and cost effective which may be suitable for underwater surveillance application

Soft Robots for Ocean Exploration and Offshore Operations: A Perspective

The ocean and human activities related to the sea are under increasing pressure due to climate change, widespread pollution, and growth of the offshore energy sector. Data, in under-sampled regions of the ocean and in the offshore patches where the industrial expansion is taking place, are fundamental to manage successfully a sustainable development and to mitigate climate change. Existing technology cannot cope with the vast and harsh environments that need monitoring and sampling the most. The limiting factors are, among others, the spatial scales of the physical domain, the high pressure, and the strong hydrodynamic perturbations, which require vehicles with a combination of persistent autonomy, augmented efficiency, extreme robustness, and advanced control. In light of the most recent developments in soft robotics technologies, we propose that the use of soft robots may aid in addressing the challenges posed by abyssal and wave-dominated environments. Nevertheless, soft robots also allow for fast and low-cost manufacturing, presenting a new potential problem: marine pollution from ubiquitous soft sampling devices. In this study, the technological and scientific gaps are widely discussed, as they represent the driving factors for the development of soft robotics. Offshore industry supports increasing energy demand and the employment of robots on marine assets is growing. Such expansion needs to be sustained by the knowledge of the oceanic environment, where large remote areas are yet to be explored and adequately sampled. We offer our perspective on the development of sustainable soft systems, indicating the characteristics of the existing soft robots that promote underwater maneuverability, locomotion, and sampling. This perspective encourages an interdisciplinary approach to the design of aquatic soft robots and invites a discussion about the industrial and oceanographic needs that call for their application

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