Kinematic modeling of a bio-inspired robotic fish

This paper proposes a kinematic modeling method for a bio-inspired robotic fish based on single joint. Lagrangian function of freely swimming robotic fish is built based on a simplified geometric model. In order to build the kinematic model, the fluid force acting on the robotic fish is divided into three parts: the pressure on links, the approach stream pressure and the frictional force. By solving Lagrange\u27s equation of the second kind and the fluid force, the movement of robotic fish is obtained. The robotic fish\u27s motion, such as propelling and turning are simulated, and experiments are taken to verify the model.<br /

Структура системи керування маршовим рухом засобу морської робототехніки з гідробіонічним рушієм

Блінцов, В. С. Структура системи керування маршовим рухом засобу морської робототехніки з гідробіонічним рушієм = Structure of the control system for march movement of marine robotics equipment with a hydrobionic propulsion / В. С. Блінцов, С. І. Ольшевський // Зб. наук. пр. НУК. – Миколаїв : НУК, 2020. – № 2 (480). – С. 68–78.Анотація. Проаналізовано принципи побудови та особливості структури систем керування засобами морської робототехніки, зокрема з гідробіоничними рушіями. Обґрунтовано доцільність використання ієрархічної структури зі значною автономністю окремих рівнів. Визначено структуру системи автоматичного керування плавниковим гідробіонічним рушієм типу тунця. Для вирішення поставлених завдань використовуються методи комп’ютерного моделювання, спеціальних розділів теорії автоматичного керування у частині синтезу нелінійних та дискретних систем керування, системи автоматизованого проектування апаратних та програмних засобів систем автоматичного керування. Розробка структури системи автоматичного керування плавниковим рушієм типу тунця та визначення її місця в загальній ієрархічній структурі системи керування засобами морської робототехніки дало змогу визначити вимоги до апаратної та програмної частин системи автоматичного керування рушієм. Синтезована схема може слугувати прототипом для побудови системи автоматичного керування рухом автономних ненаселених підводних апаратів із гідробіоничними рушіями. Використовування синтезованої раніш моделі кінематики рушія типу тунця дає змогу підвищити точність і забезпечити керованість на всіх ділянках циклу роботи плавникового рушія. На базі розробленої блок-схеми алгоритму роботи мікроконтролера можливо реалізовувати необхідні закони керування плавниковим рушієм. Подальші дослідження передбачають уточнення математичних моделей, розробку діючого зразка системи автоматичного керування та рушія і дослідження їх роботи в комплексі.Abstract. The principles of construction and peculiarities of the structure of control systems for marine robotics, in particular with hydrobionic propulsion, are analyzed. The expediency of using a hierarchical structure with considerable autonomy of individual levels is substantiated. The structure of the system for automatic control of tuna hydrofibric propulsion system was determined. Computer simulation, special sections of the theory of automatic control in the synthesis of nonlinear and discrete control systems, computer-aided design of hardware and software of automatic control systems are used to solve these problems. The development of the structure of the Tuna type automatic control system and its location in the overall hierarchical structure of the marine robotics control system made it possible to determine the requirements for the hardware and software of the automatic control system. The synthesized circuit can serve as a prototype for the construction of an automatic motion control system for autonomous, unpopulated submarines with hydrobionic propulsion. The use of the previously synthesized kinematics model of tuna propulsion engine allows to increase the accuracy and to ensure controllability in all parts of the fin cycle. Based on the developed block diagram of the algorithm of operation of the microcontroller, it is possible to implement the necessary control laws for the fin propulsion. Further research involves the refinement of mathematical models, the development of a working model of the automatic control system and propulsion and the study of their work in the complex

Mechanical Description of a Hyper-Redundant Robot Joint Mechanism Used for a Design of a Biomimetic Robotic Fish

A biologically inspired robot in the form of fish (mackerel) model using rubber (as the biomimetic material) for its hyper-redundant joint is presented in this paper. Computerized simulation of the most critical part of the model (the peduncle) shows that the rubber joints will be able to take up the stress that will be created. Furthermore, the frequency-induced softening of the rubber used was found to be critical if the joints are going to oscillate at frequency above 25 Hz. The robotic fish was able to attain a speed of 0.985 m/s while the tail beats at a maximum of 1.7 Hz when tested inside water. Furthermore, a minimum turning radius of 0.8 m (approximately 2 times the fish body length) was achieved

A comparison study of biologically inspired propulsion systems for an autonomous underwater vehicle

The field of Autonomous Underwater Vehicles (AUVs) has increased dramatically in size and scope over the past two decades. Application areas for AUVs are numerous and varied; from deep sea exploration, to pipeline surveillance to mine clearing. However, one limiting factor with the current technology is the duration of missions that can be undertaken and one contributing factor to this is the efficiency of the propulsion system, which is usually based on marine propellers. As fish are highly efficient swimmers greater propulsive efficiency may be possible by mimicking their fish tail propulsion system. The main concept behind this work was therefore to investigate whether a biomimetic fish-like propulsion system is a viable propulsion system for an underwater vehicle and to determine experimentally the efficiency benefits of using such a system. There have been numerous studies into biomimetic fish like propulsion systems and robotic fish in the past with many claims being made as to the benefits of a fish like propulsion system over conventional marine propulsion systems. These claims include increased efficiency and greater manoeuvrability. However, there is little published experimental data to characterise the propulsive efficiency of a fish like propulsive system. Also, very few direct experimental comparisons have been made between biomimetic and conventional propulsion systems. This work attempts to address these issues by directly comparing experimentally a biomimetic underwater propulsion system to a conventional propulsion system to allow for a better understanding of the potential benefits of the biomimetic system. This work is split into three parts. Firstly, the design and development of a novel prototype vehicle called the RoboSalmon is covered. This vehicle has a biomimetic tendon drive propulsion system which utilizes one servo motor for actuation and has a suite of onboard sensors and a data logger. The second part of this work focuses on the development of a mathematical model of the RoboSalmon vehicle to allow for a better understanding of the dynamics of the system. Simulation results from this model are compared to the experimental results and show good correlation. The final part of the work presents the experimental results obtained comparing the RoboSalmon prototype with the biomimetic tail system to the propeller and rudder system. These experiments include a study into the straight swimming performance, recoil motion, start up transients and power consumption. For forward swimming the maximum surge velocity of the RoboSalmon was 0.18ms-1 and at this velocity the biomimetic system was found to be more efficient than the propeller system. When manoeuvring the biomimetic system was found to have a significantly reduced turning radius. The thesis concludes with a discussion of the main findings from each aspect of the work, covering the benefits obtained from using the tendon drive system in terms of efficiencies and manoeuvring performance. The limitations of the system are also discussed and suggestions for further work are included

Building a 3D Simulator for Autonomous Navigation of Robotic Fishes

Abstract-- This paper presents a 3D simulator used for studying the motion control and autonomous navigation of a robotic fish. The simplified kinematics and hydrodynamics models are created for the simulator, including many other object models such as water, obstacles, sonar sensors and a swimming pool. The experimental results show that the use of this simulator is a realistic and convenient way to develop autonomous navigation algorithms for robotic fishes. I