Yoshiaki Nose

Approaching whales by autonomous Underwater vehicle

There are few studies on the ecology of whales in underwater except for small whales (Baird, R., 1996, Otani, S., 1998). It is hoped that through the use of Autonomous Underwater Vehicles (AUVs) new knowledge about whales can be gained. The whale makes sounds, and especially the humpback whale (Megaptera novaeangliae) makes a specific sound called a song. We started our project to develop the technology for AUVs to follow and observe humpback whales by analyzing their songs and locating them underwater. A small size passive SONAR was designed, fabricated, and fitted on the AUV AQUA EXPLORER 2000. An observation experiment was conducted in March 2001 off the Kerama Islands, Okinawa. Prior to our studies, there were no examples of AUV observations on whales anywhere in the world. This experimental observation was conducted as a joint project of the Underwater Technology Research Center at the Institute of Industrial Science in the University of Tokyo, KDDI Co. Research Institute, and the Okinawa EXPO Aquarium. The AUV succeeded in detecting a humpback whale underwater and approaching it within 50m in this experiment.

A conical laser light-sectioning method for navigation of Autonomous Underwater Vehicles for internal inspection of pipelines

This paper presents a novel sensing method for navigation of Autonomous Underwater Vehicles, AUVs, through pipelines to conduct autonomous internal inspection. Unlike remotely operated pipe inspection robots, AUVs do not have an umbilical cable and so they can easily maneuver through bent sections of pipelines and the distance they can cover is not restricted by the length of the cable. Presently pipe inspection robots come in contact with the walls of the pipe during their operation. However old and aged pipelines may have loose corroded materials or biological growth which may get detached and pollute the fluid or further damage pipe interior when the pipe inspections robots touch the walls. AUVs can operate without coming in contact with the pipe wall and so this technique is a non-contact measurement and inspection technique. The proposed navigation sensor makes use of computer vision techniques to estimate the relative position and orientation of the vehicle inside the pipe with 4 degrees of freedom, which will enable the AUV to swim through the center of the pipe. A conical laser is projected on the pipe wall and the image of the laser is acquired by a camera. The features of the image are extracted and matched with a feature database prepared apriori. The position and orientation of the matching feature record in the database gives the estimated position and orientation of the vehicle. Experiments were conducted in dry experimental pipelines to verify the performance of the proposed sensor and results are presented. Control Simulations were performed to verify the ability of the sensor to navigate an AUV. The results of these controls simulated are also presented in this paper.

Multi-sensor based AUV with distributed vehicle management architecture

The authors introduce a project to build a multisensor-based autonomous underwater vehicle (AUV) named the Twin-Burger, which is the newest vehicle of the Institute of Industrial Science, the University of Tokyo. The Twin-Burger is being designed as a versatile testbed on which the techniques as represented by software architectures can be implemented and tested. The first in-water experiment is expected in 1992. The distributed vehicle management architecture is proposed as a software architecture for the Twin-Burger. The architecture is being developed to approach the most critical problem in the distributed system, that is, how to manage heterogeneous software modules in a homogeneous structure. Performance of the software developed for this management system will be tested using a multipurpose environment simulator.<<ETX>>

Expanded interferometry and synthetic aperture applied to a side scanning sonar for seafloor bathymetry mapping

A new designed Autonomous Underwater Vehicle r2D4 for operation to 4,000 meters was built for the purpose of seafloor mapping on the oceanic ridge having hydrothermal activity in July 2003. An expanded interferometry sonar with operating frequencies of 100 kHz was installed on the AUV for high resolve bathymetry mapping, not to mention the backscatter imaging. In effect, the interferometry sonar is simply composed of three hydrophones, which are arranged at intervals of three and thirteen wavelengths in the L-shape at each side, in addition, to a side scanning sonar Klein System 2000 with operating frequencies of 100 kHZ and 500 kHz. It explains features of low cost and low power consumption. An initial survey test of the AUV was carried out up to 500 meters deep off Ryotsu port of Sado Island in July 2003. In advance of the sea test of the AUV, a test of the interferometry sonar with the barge had been carried out. L-shape array of hydrophones enables us to make a phase difference measurement successfully with high resolution. It follows that a detailed swath bathymetry was brought about. Consequently, a seafloor mapping was carried out to reveal the detail topography on the top of Kuroshima knoll in the vicinity of Okinawa islands in December 2003. The AUV is installed with the PHotonic Inertial Navigation System (PHINS), which provides inertial navigation and motion measurements of the AUV. Furthermore, since the AUV is able to move underwater very stably along planed courses, it is a proper platform in materializing the synthetic aperture of the side scanning transducers. We have been devoting ourselves to process the observation data. As a result, the synthetic aperture technique was very useful for the improvement of the seafloor bathymetry mapping as expected.

Terrain Based Localization Method for Wreck Observation AUV

In this paper, we propose a wreck observation system using an AUV (Autonomous underwater vehicle) and introduce an AUV that we are developing for this system. Furthermore, we propose a terrain based localization method for the positioning of the AUV, which does not depend on external and costly help such as transponder based positioning systems. The proposed method is robust against altitude offset compared to conventional terrain based methods. The results of the simulation, performed using the data collected during a sea experiment, demonstrate the efficiency of the proposed method

Combined energy storage and three-axis attitude control of a gyroscopically actuated AUV

This research develops a system to combine energy storage and attitude control functions in control moment gyros (CMGs) for application onboard autonomous underwater vehicles (AUVs). This is proposed as part of a hybrid energy storage system to allow AUVs to perform their missions with no chemical battery at all. A geometric study of the interactions between the kinetic energy and angular momentum stored in a CMG pyramid is performed. This forms the basis of a control algorithm that allows the energy mechanically stored in the rotation of the CMG flywheels to power the electronics of the robot, whilst simultaneously controlling its three-axis attitude. The proposed system is implemented onboard the CMG actuated AUV dasiaIKURApsila and underwater experiments are performed to demonstrate combined energy storage and three-axis attitude control.

Autonomous underwater sampling using a manipulator and stereovisual servoing

We propose a system, composed of a manipulator and a stereovision module mounted on the autonomous underwater vehicle Twin-Burger 2 to sample underwater jellyfish-like small animals. Visual servoing of the robot is performed with the data from the stereovision module. A moving target and a LED fixed on the manipulators end are tracked in real time. The manipulator is designed to avoid any motion perpendicular to the main axes of its elements that would generate drag forces and perturb the vehicles position. An experiment in which the robot tracks and catches a submersed ball with the manipulator is presented.

Passive tracking of multiple diving sperm whales using single hydrophones at two mobile locations

A simple method using only two hydrophones, each loosely deployed from separate mobile platforms, has been developed to simultaneously track several vocalizing sperm whales. The separation distance of several hundred meters between the hydrophones implies that a particular whale could present vastly different beam orientations towards them, thus precluding use of any specific relationship between the click signal levels at the two locations for the purpose of whale localization. This method utilizes time‐of‐arrival of the direct clicks and their surface reflections and matches them at the two hydrophone locations. Whales are segregated on the basis of the set of observed time delays. Click parameters such as interpulse interval and average click frequency are proposed to be used as secondary data for the purpose of track refinement. Depth profile of the whales is obtained independent of the separation distance between the two hydrophones. However, knowledge of the separation distance between the hydrophon...

Semi-autonomous touching of underwater object by unmanned untethered vehicle

To investigate an underwater object in detail, it is essential for underwater vehicles to touch the object. However, for the Unmanned Untethered Vehicle (UUV) touching an underwater object is not an easy task because those robots are not apt to be operated remotely via acoustic link which is slow in communication rate and results in a long time-lag. In this paper, on the basis of time-lag compensation by stored video images, ranging technique by image processing and station keeping by visual feedback, a semi-autonomous system is proposed that enables the UUV to touch an underwater object by its hand from any direction. The proposed system is demonstrated experimentally through tank tests using testbed robot Tri-Dog 1 to which a two-degree-of-freedom robot hand is fitted.