Recently, automation and unmanned technologies have been developing rapidly in various industries. In the field of traffic and transportation, the development of unmanned technologies is remarkable, and it is already moving on to the practical stage in the field of transportation infrastructure such as automobiles, railways and aircrafts. The development of automation and autonomy technologies is expected not only to save manpower and reduce labor, but also to eliminate human errors and greatly contribute to ensuring our safety. This paper focuses on our autonomous technology for ships and also introduces the history of our development processes. In view of the greater use of the autonomous technology in society in the future, this innovation is considered to be also used for inspection work on marine infrastructure such as breakwaters and revetment structures. With this notion in mind, we have conducted an experiment to confirm whether our autonomous vehicles are suitable to meet such a purpose. In addition, we describe the expectations, challenges, and prospects for practical applications of the technology in other areas, such as marine traffic and security, as well as inspection applications for marine infrastructure.

In this paper, I will provide an overview of Marine Drone 3.1, a USV control system for mini-boats, featuring the embedded OS 'F-OS' that target 8/16/32bit microcontrollers. Marine Drone 3.1 boasts high portability and unique strengths in the current market environment characterized by semiconductor shortages. It was developed in consideration of future software verification, with a focus on avoiding the inclusion of SOUP items. Comprised of 56 tasks, Marine Drone 3.1 features an interactive shell for serial communication and external APIs. This paper describes the functionalities, control software, and external APIs of Marine Drone 3.1. The author hopes that this project will contribute to the advancement of small marine drones.

In the case of automatic navigation in an offshore area, as the target area is wide and the navigation environment is sparse with few obstacles, highly accurate route-tracking is not generally required. On the other hand, when automatic navigation is performed in a relatively restricted area, such as a harbor, the target area has a dense environment with many obstacles such as other vessels and buoys, which requires highly accurate route tracking. In addition, the system must navigate a course that can maintain appropriate distances from obstacles in preparation for unexpected external forces such as wind. In this paper, we propose a method to generate an appropriate navigation route to satisfy different requirements of two chart types, namely charts for automatic navigation in offshore areas that are defined as sparse wide-area maps and those for automatic berthing and unberthing that are defined as dense narrow-area maps. The proposed method was then applied to the actual environment to verify its usefulness, and then automatic navigation was performed using a generated route.

In recent years, research and development of the automatic driving technology for automobiles, air vehicles and ships etc. have actively been carried out. The foundation of the technology is self-localization, a technique that enables the moving object to estimate its position in space. Mapping is an essential element for this self-localization. In this paper, the 3D map information required for maritime autonomous surface ships (MASS) is discussed. The authors outline related technologies for automobiles and urban infrastructures and examine the possibility of using such information for MASS. We also explain the results of a trial to display route information for MASS on existing digital maps.

In recent years, the maritime industry has actively proceeded with research and development on technologies related to maritime autonomous surface ships (MASS) and their remote operation systems. Demonstrations of these technologies have been carried out using actual vessels. At the same time, individual technological elements related to MASS have also been developed. Among these technological advances, those associated with cyber security are of particular importance. This paper investigates the use of 'LTE over IP' which is designed to ensure secure communication by enabling LTE technology for mobile phones to be used in IP networks. The authors examined how the use of 'LTE over IP' affects the communication characteristics of a remote-control system.

The tightening method using impact wrenches is used rather frequently to clamp bolted joints requiring high workability. The tightening torque is applied in the form of impact forces generated by a rotating hammer, which is powered by compressed air, hydraulic force or electric power. The primary advantage of impact wrenches is that the tightening operation can be completed in a short time. However, the accuracy of the generated bolt force is not so high, because of the complicated mechanical behavior caused by the action of impact forces. In this paper, the tightening process of bolted joints by use of impact wrenches is studied from the mechanical point of view, and the relationship between the nut rotation angle and the repeat count of impact forces is formulated. Based on the foregoing results, a practical tightening guideline is proposed by considering the effects of joint stiffness and impact friction coefficient that vary in the progress of the tightening operation.

  Heat transfer involved with non-Newtonian fluid flows is encountered in material processing for the shipbuilding as well as other heavy machinery industries. In such applications particularly for drawing, extrusion, coating, etc., the thermal procedures involve the combined form of Couette and Poiseuille flows as the axially moving cylindrical rod continuously exchanges heat with the surrounding environment. In this numerical study, using the fully developed laminar velocity field obtained by applying the modified power-law model, the effects of viscous dissipation and fluid axial heat conduction on thermally developing heat transfer of non-Newtonian fluids flowing in a concentric annulus with a moving core are investigated for the thermal boundary conditions of constant temperature and/or constant heat flux at the cylinder walls. The flow temperature distribution is obtained for an axially infinite extent by solving the elliptic type energy equation and the solution is based on a coordinate transformation.

  The effects of the moving core velocity, rheological property, Brinkman number, Peclet number and geometry of the annuli (radius ratio) on the temperature distribution and Nusselt number at the cylinder walls are discussed.