Toshio Hori

Sensor network for supporting elderly care home

The paper presents an ultrasonic sensor network system that can be utilized in elderly care homes. One of the problems of an aging society is the shortage of carers in homes for the aged; the shortage imposes an increasing workload on carers and leads to a deterioration of the quality of care for the elderly. The authors developed an ultrasonic sensor network system to reduce the workload on carers. The system monitors the elderly people in a nursing room continuously and remotely, and, when it detects accident-prone events or accidents of the elderly, it notifies carers about the occurrence of such events. The system was installed in a nursing home in Tokyo and has been running for several months. The paper describes the background of the research, the system overview, and results obtained during its real operation.

Minimally privacy-violative system for locating human by ultrasonic radar embedded on ceiling

Violating the privacy of individuals with systems that measure daily human activities is unacceptable in our society. In this paper, the authors propose a system using ultrasonic radar embedded in the ceiling of a room to locate human individuals with a minimum violation of privacy. It is expected that this system is used in the prevention of accidents among aged persons suffering from Alzheimers disease. The proposed system determines the three-dimensional position of a persons head by assuming that the human head is an object that will move at a relatively high vertical position within a living area. In this study, the method used to locate the human head is analyzed theoretically from the perspective of acoustics. The feasibility of the proposed system is confirmed by experimental results using a system constructed by the authors.

Minimally privacy-violative human location sensor by ultrasonic radar embedded on ceiling

A system observing human daily activities that may violate privacy is unacceptable in our society. This paper proposes a minimally privacy-violative system for locating a person using ultrasonic radar embedded in the ceiling of a room. One of the presumable applications is a system for preventing aged people suffering from Alzheimers disease from accidents. The proposed system can determine the 3D position of a persons head by assuming that the human head is an object that will move at a relatively high vertical position in a living area. The system does not input unnecessarily rich information such as images using a camera so that it can reduce the possibility for violating privacy. The authors constructed an experimental system that consists of 18 ultrasonic transmitters and 32 receivers which are embedded in the ceiling of a room. Experimental results confirmed the feasibility of the proposed system.

Pervasive sensor system for evidence-based nursing care support

A remote keyboard-display terminal system has buffer transfer and character generator hardware, by which it accesses the central memory directly without significantly interfering with the central processing unit, organizes coded data by linked list, and presents visual data without one-to-one correspondence between display screen position and central memory location.This paper introduces a pervasive sensor system for nursing homes, where daily activities of elderly persons are monitored by pervasive sensors all the time. Deterioration in the quality of nursing care for the elderly has become one of the biggest problems in the aging society and the authors have been challenging the problem by sensors embedded in a nursing room. The sensors accumulate position information of a subject person and his wheelchair, then it is utilized for prompt assists for the subject and also used for obtaining his life log. In our experiments, we obtained position data of an elderly person for a month and a half and analyzed his sleeping hours and the number of times of going to a restroom. This paper presents the concept of the system, overview of the current system and experimental results obtained

Quick realization of function for detecting human activity events by ultrasonic 3D tag and stereo vision

This paper proposes a system for quickly realizing a function for robustly detecting daily human activity events in handling objects in the real world. The system has three functions: 1) robustly measuring 3D positions of the objects; 2) quickly calibrating a system for measuring 3D positions of the objects; 3) quickly registering target activity events; and 4) robustly detecting the registered events in real time. As for 1), the system realizes robust measurement of 3D positions of the objects using an ultrasonic 3D tag system, which is a kind of a location sensor, and robust estimation algorithm known as random sample consensus (RANSAC). The paper evaluates the robustness by comparing RANSAC with a least-squares optimization method. As for 2), the system realizes quick calibration by a calibrating device having three or more ultrasonic transmitters. Quick calibration enables the system to be portable. As for 3), quick registration of target activity events is realized by a stereoscopic camera with ultrasonic 3D tags and interactive software for creating 3D shape model, creating virtual sensors based on the 3D shape model, and associating the virtual sensors with the target events. The system makes it possible to quickly create object-shaped sensors to which a new function for detecting activity events are added while maintaining the original functions of the objects.

Improvement of position estimation of the ultrasonic 3D tag system

This paper presents an improvement of position estimation of the ultrasonic 3D tag system developed by the authors. We are involved in a joint project of developing an omnidirectional autonomous mobile robot system and our ultrasonic 3D tag system was employed as an indoor GPS system to the robot. However, the position estimation error of current system is not enough to support the mobile robot, that is, position estimation error of the system is about 50 mm by using the currently implemented robust estimation methods. By employing a new estimator based on a nonparametric filter, the estimation error was reduced to less than 20 mm on average. Moreover, the new method is much robuster than the previous methods. This paper introduces an overview of the system and experimental results of simulations.

Delivery task by a humanoid robot in the sensorized environment

We propose a human support system by a humanoid robot in the living environment. For supporting humans, the robot has to follow a human in order that he/she can give commands to the robot at any time, anywhere. In this paper our target is to develop a system in which a human can command the robot to pick up daily objects and to deliver the objects to him/her. Using the sensorized living environment, where a lot of ultrasonic sensors are distributed on the walls and the ceiling, the robot can obtain the 3-dimensional positions of human and the targets. The robot performs these tasks using the information and other information obtained from devices that are equipped with the robot.

Design and implementation of reconfigurable middleware for sensorized environments

This paper describes a middleware which the authors developed to implement distributed sensor networks. The authors have been developing sensorized environments which have hundreds of sensors and can monitor human daily activities in real time. All sensors in the environment should be connected and organized into a sensor network because no single sensor can cover the whole environment. The middleware developed by the authors supports easy implementation of such sensor network. The design and implementation of the middleware, especially the generic programming and pattern-oriented approach for I/O device handlers, are presented in this paper.

Distributed sensor network for a home for the aged

This paper introduces an embedded distributed sensor network for a home for the aged which monitors positions of elderly people in a nursing room. The system employs about one hundred ultrasonic sensors and attaches an ultrasonic emitter to a wheel chair which an elderly person uses. The system tracks the emitters position continuously and notifies caregivers when the wheel chair enters one of preset regions where accidents are likely to occur. This paper describes the background of the development and system configuration with a preliminary experimental result.

Improving sampling rate with multiplexed ultrasonic emitters

This paper presents a position estimation method for multiple ultrasonic emitters which are activated simultaneously. Locations of ultrasonic emitters are generally calculated from distance data obtained at receivers, but the emitters must be activated one after another to avoid crosstalk. Thus, the sampling rate for each emitter decreases as the number of emitters increases. The authors solved this problem by activating multiple emitters simultaneously and applying a newly developed position estimation algorithm. This paper presents the theoretical analysis and the results of simulations and experiments.