Masakazu Arima

Modelling and motion simulation of an underwater glider with independently controllable main wings

The purpose of this research is to provide an underwater glider with high manoeuvrability. This paper deals with the modelling and motion simulation of an experimental vehicle named ‘ALEX’ as a test-bed for an underwater glider with independently controllable main wings. ALEX was designed to realise high performance manoeuvrability. The main wings, rudder, elevator, movable balance weight and vent-blow valves can all be controlled by an on-board microcomputer system. The simple cylindrical shape with a NACA0050-shaped nose cone and main wings with the NACA0009 section were found to be suitable for modelling and estimating the hydrodynamic forces. A computational fluid dynamics (CFD) technique was introduced to estimate the hydrodynamic forces acting on the ALEX glider such as lift and drag under various conditions for the angles of incidence for both wings and environmental flow, i.e., the angle of attack. Equations of motion were also formulated for the modelling of ALEX. Motion simulation was conducted to clarify the characteristics of the ‘underwater glider with independently controllable main wings’ in comparison with a conventional ‘underwater glider with fixed main wings’. Results of the motion simulations were compared with the actual experiments. Several kinds of motion simulations in diving corresponded well with the motions of ALEX actually observed in the experiment tank.

Development of an Autonomous Facial-Expression Monitoring System for Safe Work Environments

The purpose of this research is to develop an autonomous facial-expression monitoring system for elderly and/or disabled people who work at various kinds of facilities. The authors have established a system which follows ones facial expression automatically. This system consists of Microsofts KINECT sensor and plural network cameras. The KINECT sensor has the ability to detect a subjects posture and skeletal position in three dimensions. At least two network cameras are autonomously controlled so as to follow the subjects face from different directions while walking around in the work space. The rest of the network cameras follow the subjects activities by zoom out viewing. Field experiments were conducted in the Plant Factory Research Centre of Osaka Prefecture University, Japan. A disabled persons face was followed by the system during work, and its effectiveness and validity demonstrated.

Development of an autonomous surface station for underwater passive acoustic observation of marine mammals

The purpose of this research is to develop a solar-powered autonomous surface vehicle (SASV) for the use of ocean environment monitoring and underwater passive acoustic monitoring of marine mammals. Measuring items of the logger version CTD with optical fast DO sensor are depth, temperature, conductivity, salinity, dissolved oxygen, chlorophyll and turbidity. The authors have also developed kinds of underwater passive acoustic monitoring systems (UPAMSs) for establishing a soundness index of the ocean, and contributing to preventative safety measures for collision avoidance of high-speed vessels and cetaceans. A practical application of the SASV can be watching over swarm intelligent underwater vehicles. This SASV consists of a couple of solar panels with a charge-and-discharge controller, an embedded PC, a couple of thrustors, a GPS device and a 3-axis digital compass for navigation. The SASV can be operated in autonomous control mode and manual control mode by a small game controller. Feature of this small-sized, lightweight and low-cost SASV is easy handling and long-term operation. This paper deals with its design concept, hardware components, control software, and trial run.

Development of a four-channel underwater passive acoustic monitoring system for the use of underwater vehicles

The purpose of this research is to develop a four-channel underwater passive acoustic monitoring system for the use of underwater vehicles. Humans have received abundant blessings of the ocean, and thus it is very important to recognise marine biodiversity and to maintain sound ocean ecosystems for the sustainable utilisation of the ecosystem services. Final goal of this research is to realise a long-term and wide-range monitoring of marine mammals using autonomous underwater vehicles, and to evaluate the healthiness of ocean ecosystems and environments. Underwater glider has no propulsive machinery, and then it is one of the most suitable underwater vehicles for acoustic observation. It is widely known that killer whale is the top predator of ocean food chain. Recently, passive acoustic monitoring (PAM) of marine mammals has appeared in the spotlight. This paper deals with a 4-channel underwater passive acoustic monitoring system. Maximum operational depth is 400 metre. The system consists of four hydrophones, pre-amplifier with anti-aliasing low-pass filter, a 4-ch portable recorder. It is also equipped with a 3-axis digital compass, a GPS device, and a 2-ch serial data logger so as to estimate the accurate direction of sound source even though the system may be drifted in the waves.