Hiromichi Hashizume

Caretta : a system for supporting face-to-face collaboration by integrating personal and shared spaces

In this paper, a system called Caretta that integrates personal and shared spaces to support face-to-face collaboration is described. We use PDAs and a multiple-input sensing board for personal and shared spaces, respectively. Users of Caretta can discuss and negotiate with each other in the shared space by manipulating physical objects, while they individually examine their ideas in their own personal spaces. Caretta allows users to participate in group activities interchangeably and seamlessly using both these spaces. Caretta is applicable to various collaborative tasks. In this paper, it supports users in urban planning tasks. User studies of Caretta demonstrated that it allowed users to collaborate in a flexible fashion: users could work individually in their personal spaces at their own pace, cooperatively work together in the shared space, and smoothly transition between both of the spaces.

Toss-it: intuitive information transfer techniques for mobile devices

In recent years, mobile devices have rapidly penetrated into our daily lives. However, several drawbacks of mobile devices have been mentioned so far. The proposed system called Toss-It provides intuitive information transfer techniques for mobile devices, by fully utilizing their mobility. A user of Toss-It can send information from the users PDA to other electronic devices with a toss or swing action, as the user would toss a ball or deal cards to others. This paper describes the current implementation of Toss-It and its user studies.

Fast and Accurate Positioning Technique Using Ultrasonic Phase Accordance Method

An innovative measurement technique for use by positioning systems using ultrasonic signals was developed. The advantage of this technique is that it can accurately identify the relative distance and orientation between devices by using an one-time ultrasonic packet. It is therefore especially useful for ubiquitous computing applications where people with mobile devices continuously change their positions in indoor environments. The technique, which is named phase accordance method, uses two or more carriers in ultrasonic communication. A special ultrasonic burst signal, called sync pattern in the header part of the communication packet gives the base point of the time measurement. The whole time difference calculation is then carried out using this base point. An experiment based on the proposed method proved that the technique attains remarkable performance, namely, errors of less than plusmn 1 mm in three meter distance measurements and less than 0.5 degree errors in the zero, ten, twenty, and thirty degree measurements.

A system for supporting group learning that enhances interactions

In this paper, we describe and evaluate a system for supporting group learning that enhances interactions among learners. To date we have constructed several systems for supporting collaborative learning. One of the aims of CSCL is to promote mutual learning through interactions and discussions among learners. Our previous experiments, however, have shown that these systems may not be so effective for supporting interactions and discussions at times. In order to enhance interactions further, a system should support externalization of each learner in an easily recognizable manner. Through such externalization, learners can actively collaborate or conflict with each other through discussions.The proposed system integrates a board game and a computer simulation, and is used for studying urban planning and environmental problems. Each learner externalizes and represents his/her own ideas on a board game, which allows him/her to actively participate in a learning situation and to share the representations with other learners. The computer simulation helps the learners to understand the status of the town constructed on the board game.Several experiments were carried out in a public elementary school. The results show that our system is effective for enhancing interactions, discussions and learner engagement.

Design of an interactive system for group learning support

In this paper we describe our project to design a system that can be used as a teaching aid to support group learning in elementary school education. The system enhances the learning outcome for pupils who have studied environmental problems using a textbook, by allowing them to construct a town in a physical space and to assess the construction through computer simulations. The system was designed in collaboration with teachers and their pupils in elementary schools. Lessons learned from the collaborative design processes are described.

Smart phone localization method using dual-carrier acoustic waves

We describe an indoor localization technique for smart phones. Our new method, called the Frequency Division Multiplexing Phase Accordance Method (FDM-PAM), uses a beat called a sync pattern composed of a pair of sinusoidal waves with slightly different frequencies, which is similar to our original ultrasound ranging technique called the Phase Accordance Method (PAM). By generating multiple sync patterns with different central frequencies and transmitting them from different speakers, FDM-PAM conducts time-difference-of-arrival (TDOA) multilateration for localizing smart phones. In the current implementation of FDM-PAM, the 2D indoor position of a smart phone can be estimated. Three sync patterns are generated by using two out of six sinusoidal waves with frequencies ranging from 14.75 kHz to 17.25 kHz. The transmission of the sync pattern from the speakers lasts 4 ms. Through experiments, we have confirmed that FDM-PAM achieves accuracy of around 10 cm using only a short burst transmission, which indicates that the localization technique is sufficiently rapid and accurate.

Design and implementation of a robust and real-time ultrasonic motion-capture system

In this paper, we propose an innovative motion-capture system using ultrasonic communications. Compared with existing commercial motion-capture systems that use optical or magnetic sensing, the proposed system can provide a cost-effective solution for industrial and entertainment applications. To design and implement the system, a distance-estimation method called the Extended Phase Accordance Method (EPAM), which can measure the distance to a moving object with a standard deviation of less than 1 mm, was devised. To improve the capture rate of the proposed system, the EPAM algorithm was implemented in a field-programmable gate array (FPGA). The current version of the system conducts motion capture using five markers attached to a user. It can work at around 10 frames per second (fps), with an error of less than 55 mm and a standard deviation of 42 mm. This demonstrates a moderate level of accuracy, which will be useful for several applications.

An accurate technique for simultaneous measurement of 3D position and velocity of a moving object using a single ultrasonic receiver unit

An ultrasonic localization system is described in the paper. To the best of our knowledge, this is the first system that can simultaneously identify not only the 3D position [1], but also the velocity of a moving object. The proposed system uses an original and innovative method called Extended Phase Accordance Method (EPAM) that can precisely identify the distance between an ultrasonic microphone and a moving transmitter by rapidly estimating the frequency shift of the transmitted signal. One remarkable feature of the proposed system is the use of a single compact receiver unit, which will reduce deployment labor and costs. Experiments demonstrate that the proposed system shows the 3D position and velocity estimation with sufficient accuracy.

A scalable tracking system using ultrasonic communication

Recently a new method of indoor ultrasonic localisation was introduced. It is called the phase accordance method and the authors claim that with this technology they could measure the 2D coordinates of the transmitter by a single receiver and a single transmission of ultrasound. Also this method is reported to be able to locate static objects more accurately than conventional methods. In this paper we evaluated the ability of the method to locate moving objects. Experiments with a prototype system and a moving robot were conducted, which showed satisfying results. Issues to be investigated in the future work are described.

An accurate and compact 3D tracking system using a single camera and ultrasound

We propose a novel technique for 3D tracking that integrates a single camera and ultrasound. We use ultrasound with the Extended Phase Accordance Method to measure the distance accurately to a moving target and the camera for identifying the 2D position of the target on the image plane. A prototype system consists of a target unit mounting one ultrasound transmitter and three infrared LEDs surrounding it, and a receiver unit with one inexpensive camera and one ultrasound receiver. We implemented these units in a lightweight and compact way (receiver unit size: 55 mm × 44 mm) to make the system robust to non-line-of-sight problems that frequently occur in trilateration or multicamera-based systems. To improve the ranging performance, we applied phase characteristic compensation of the ultrasound transducers by interpolating with a B-spline function and creating a compensated curved surface. Experimental results show that root-mean-square errors of the proposed system are 1.20 mm and 1.66 mm for static and mobile (target velocity: 1.0 m/s) settings, respectively. Thus, the performance of the system is comparable with that of high-end systems. Limitations of the proposed system and its possible applications are also discussed.