Hirohisa Morikawa

Biology-Inspired Precision Maneuvering of Underwater Vehicles

This paper describes the use of a mechanical pectoral fin as a new device for maneuvering and stabilizing an underwater vehicle. The mechanical pectoral fin consists of three servo-motors, which respectively generate a rowing motion, a feathering motion, and a flapping motion. Optimization of the parameters of fin motion so as to generate maximum propulsive force in terms of flow condition and motion pattern revealed that the lift-based rather than the drag-based swimming mode is suitable for generation of propulsive force in uniform flow, whereas the drag-based rather than the lift-based swimming mode is suitable for generation of propulsive force in still water. The underwater vehicle equipped with two pairs of mechanical pectoral fins has not only quite a good propulsive performance, but also a variety of maneuverability in hovering condition. The task sharing by fore and aft pairs of mechanical pectoral fins enables a precise Point To Point control in 3-D underwater space that needs simultaneous performance of azimuth control, position control in horizontal plane and depth control. The drag-based swimming mode of the mechanical pectoral fin rather than the lift-based swimming mode is suitable for the motion control of the underwater vehicle that needs a prompt response under disturbances such as waves.

Bio-mechanisms of swimming and flying

Chapter 1: An Engineering Perspective on Swimming Bacteria: High-Speed Flagellar Motor, Intelligent Flagellar Filaments, and Skillful Swimming in Viscous Environments, Y. Magariyama, S. Kudo, T. Goto, and Y. Takano.- Chapter 2: Euglena Motion Control by Local Illumination, A. Itoh.- Chapter 3: Thrust-Force Characteristics of Enlarged Propulsion Mechanisms Modeled on Eukaryotic Flagellar Movement and Ciliary Movement in Fluid, S. Kobayashi, K. Furihata, T. Mashima, and H. Morikawa.- Chapter 4: Resonance Model of the Indirect Flight Mechanism, H. Miyake.- Chapter 5: On Flow Separation Control by Means of Flapping Wings, K.D. Jones, M. Nakashima, C.J. Bradshaw, J. Papadopoulos, and M.F. Platzer.- Chapter 6: Outboard Propulsor with an Oscillating Horizontal Fin, H. Morikawa, A. Hiraki, S. Kobayashi, and Y. Muguruma.- Chapter 7: Three-Dimensional Maneuverability of the Dolphin Robot (Roll Control and Loop-the-Loop Motion), M. Nakashima, Y. Takahashi, T. Tsubaki, and K. Ono.- Chapter 8: Fundamental Study of a Fishllike Body with Two Undulating Side-Fins, Y. Toda, T. Suzuki, S. Uto, and N. Tanaka.- Chapter 9: Biology-Inspired Precision Maneuvering of Underwater Vehicles, N. Kato, H. Liu, and H. Morikawa .- Chapter 10: Optimal Measurement Strategies for Environmental Mapping and Localization of a Biomimetic Autonomous Underwater Vehicle, J. Guo, F.-C. Chiu, S.-W. Cheng, and P.-C. Shi.- Chapter 11: Experimental and Analytical Study of the Schooling Motion of Fish Based on Two Observed Individual Motions: Approaching Motion and Parallel Orienting Motion, Y. Inada, K. Kawachi, and H. Liu.- Chapter 12: Neural Basis of Odor-Source Searching Behavior in Insect Microbrain Systems Evaluated with a Mobile Robot, R. Kanzaki, S. Nagasawa, and I. Shimoyama.- Chapter 13: Architectures for Adaptive Behavior in Biomimetic Underwater Robots, J. Ayers.- Chapter 14: Efficiency of Biological and Artificial Gills, K. Nagase, F. Kohori, and K. Sakai.- Subject Index.

Development of a biologically inspired locomotion system for a capsule endoscope.

A capsule endoscope has a limited ability to obtain images of the digestive organs because its movement depends on peristaltic motion. To overcome this problem, capsule endoscopes require a propulsion system.

A novel propulsion mechanism using a fin with a variable-effective-length spring

Since the propulsion mechanism in fluid using an elastic fin, such as the caudal fin or the pectoral fin of fish, is effective. However, the optimum elasticity of the fin is not constant and changes with the movement task and environment. It is very difficult to exchange fins of different stiffness while the robot is swimming. Thus, we attempt to develop a variable-stiffness fin with a variable-effective-length spring. The apparent stiffness of this spring can be changed dynamically. The present paper describes the thrust force, and flow velocity corresponding to the self propelled speed of the fin in a uniform flow. And we compared the thrust efficiency in a uniform flow with the evaluating value of the thrust efficiency in a no flow. Furthermore, we developed a flow visualization system and discussed the flow-field around the fin in a uniform flow.

Bioinspired Aquatic Propulsion Mechanisms with Real-Time Variable Apparent Stiffness Fins

We aimed to develop the aquatic propulsion mechanisms of Paramecium like and fish like robots that consist of real-time variable stiffness fins. For the aquatic propulsion mechanisms of the Paramecium like robot, we have used fins with ICPF (Ionic Conducting Polymer gel Film) actuator to change its stiffness for representing ciliary movement. For the aquatic propulsion mechanisms of the fish like robot, we have used a fin with variable effective length spring which changes its apparent bending stiffness. We discussed the movement of the real-time variable stiffness fins and thrust force characteristics of the propulsion mechanisms in fluid.

A Locomotive System Mimicking Pedal Locomotion of Snails for the Capsule Endoscope

Recently, a capsule endoscope has been used for medical diagnosis for the small intestine. It doesn’t cause much pain to patients during the operation unlike a conventional endoscope. However, the capsule endoscope has some limitation in obtaining an image of the digestive organ because its movement depends only on the peristaltic motion. To overcome this problem, the locomotive system is necessary for the capsule endoscope. In this paper, we proposed two locomotive systems, mimicking the locomotive mechanism of snails and earthworms. First, we developed a scale up prototype of the crawler mimicking the locomotive mechanism of snails. It has five segments and four joints, where two of four joints are actuated by DC motors. In the front and rear segments, a suction cup is installed, which consists of an electromagnetic solenoid and a rubber sheet. In locomotion experiments on a horizontal plane and on an inclined plane of 10 degrees, we confirmed that the developed crawler could locomote at the speed of 17 mm/cycle. Secondly, we developed a prototype crawler mimicking the locomotive mechanism of snails and earthworms. It can elongate and contract itself longitudinally by using shape memory alloys (SMA) and compression springs. By using this mechanism, we could successfully shrink its size. This prototype crawler could stick and locomote on a horizontal plane. In locomotion experiments on a horizontal plane, we confirmed that the developed crawler could locomote at the speed of 3 mm/cycle. We think that this locomotive system is useful for the capsule endoscope for digestive organs.

Mechanical Properties of the Caudal Fin Resulting from the Caudal Skeletal Structure of the Bluefin Tuna

The objective of our study was to investigate the effect of caudal fin behavior resulting from the caudal skeletal structure of tuna on the propulsive performance. In this paper, the caudal skeletal structure and mechanical properties on the caudal fin of bluefin tuna (Thunnus thynnus) were examined. The Young’s modulus of fin rays composing the caudal fin was obtained. A two dimensional oscillating wing theory was applied to the caudal fin sinusoidally oscillating in a uniform flow. Then the pressure distribution over the fin was calculated and the fin deformation was obtained. It was found that a phase delay existed between the leading edge and the middle part of the fin.

Variable stiffness fin for propulsion in fluid

Ciliary movement has an advantage for propulsion if the body is covered by many cilia such as in the case of a paramecium; the body is able to rotate in situ and change its direction io propel jtself M small spaces. Thus, we made the enlarged propulsion mechanism in fluid modeled on ciliary movement equipped with a motor OR its base and two types of the variable stiffness fins that realize the effective stroke and recovery stroke of ciliary movement. We discussed the movement of the variable stiffness fin and thrust force Characteristics of the enlarged propulsion mechanism in fluid.

Thrust—Force Characteristics of Enlarged Propulsion Mechanisms Modeled on Eukaryotic Flagellar Movement and Ciliary Movement in Fluid

We have noted the utility of the eukaryotic flagellar movement and the ciliary movement for propulsion in fluid, and developed two enlarged propulsion mechanisms modeled on eukaryotic flagellar and ciliary movements. For the propulsion mechanisms modeled on eukaryotic flagellar movement, we used the model of the active sliding of microtubules in eukaryotic flagella: active sliding between two rows of electromagnets on flexible beams corresponding to the active sliding of microtubules was made for the bending of the mechanism. For the propulsion mechanisms modeled on ciliary movement, we made a bending mechanism equipped with a motor on its base and a variable-bending stiffness fin that realizes the effective stroke and recovery stroke. The vari-able-bending-stiffness fin consists of two flexible sheets and electromagnets. The electromagnets control the frictional force between the two flexible sheets. Bending stiffness is controlled dynamically by changing the frictional force between the two flexible sheets. We discuss the thrust force characteristics of the two propulsion mechanisms.

222 Analysis on swimming behavior of dolphin with artificial tail flukes

Dolphins have high propulsion and maneuvering performances. Dolphin’s tail flukes play an important role to generate propulsive force. We paid attention to a dolphin that lost most part of its tail flukes by disease kept in an aquarium, Okinawa, Japan. The dolphin could swim by attaching artificial tail flukes as well as a normal dolphin. The objective of this study is to discuss the effectiveness of the artificial tail flukes for the swimming of the dolphin by estimating the propulsive forces obtained theoretically using data on the behavior of the tail flukes and swimming number.