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The color Doppler method is widely used for velocity imaging, in particular in the medical application of circulatory blood flow visualization. However, the accuracy of medical systems and their observable velocity range are not always sufficient for other applications such as industry measurements. We developed a new velocity-imaging algorithm to overcome these shortcomings and confirmed the performance in airborne ultrasound. In this paper we describe the signal-processing algorithm and also refer to an experiment to acknowledge the performance. The simulation results showed that the proposed method could attain significant improvements in both accuracy and estimation range in comparison with the color Doppler method. In this paper we show the estimation results within a wide range of signal-to-noise ratios, as well as sector scan images obtained by color Doppler and the proposed method. The effects of changing the design parameters of the transmission signals are also discussed.

In airborne acoustic imaging the synthetic transmit aperture (STA) technology is widely used to improve the lateral resolution limited by the aperture of the microphone array. As for an STA system we use multiple speakers in combination as well as the receiver array, knowing the exact radiation pattern of a speaker is the key factor to properly operate the synthesis system. The ultrasonic signals from a transmitter always have uneven signal strength over the imaging space. Phase changes also occur depending on the distance and direction from a transmitter. As a consequence, a non-ideal radiation pattern of a transmitter used for identifying an imaging space degrades imaging results. We propose an effective measurement method for the transmitter's non-ideal radiation pattern based on new phase only imaging technology of wall-reflected sound wave. We utilize a deconvoluting Wiener filter for compensating the siderobes of receiver sensitivity pattern.

In an acoustic imaging system, ultrasonic transmitters always have uneven signal strength in the imaging space. Phase changes also occur depending on the distance and direction. In this paper, a new approach to decrease the effect of a transmitter's radiation pattern in acoustic imaging is proposed. We compensated for the transmitter's radiation pattern and reconstructed acoustic images using the Synthetic Transmit Aperture imaging technique. The compensation was based on the radiation pattern obtained from real measurements and using a Wiener filter. The purpose of the work was to compensate for a nonideal radiation pattern of the ultrasonic transmitter for both phase and amplitude aspects. An airborne imaging experiment was conducted using a two-dimensional (2D) receiver array and a 2D transmitter array to verify the effectiveness of our proposed method. The results showed an improvement in the vertical angular resolution of reconstructed three-dimensional images.

We propose a new technique for acoustic imaging that employs a back-projection algorithm to process signals from a static ultrasonic microphone array. To obtain the projection data for a target, we integrate the time distribution of received signal powers gained by pulse compression with the Radon transform of a sound field in polar coordinates. The proposed method is expected to improve angular resolution. In this paper, we describe the principle of this algorithm, explaining how it improves the resolution and performs better than conventional methods. Deconvolution is used to improve the quality of the images obtained. We have conducted computer simulations to verify the performance of the proposed algorithm. From these simulations, the angular resolution of the images achieved by the proposed technique was shown to be double that obtained by a conventional beamforming method. In our future work, we plan to conduct experiments with real environments and investigate the theoretical aspects of the proposed method more deeply.

We have developed an ultrasonic sound processing system for 3D imaging with 128 microelectromechanical systems (MEMS) microphones and a highly configurable field programmable gate array (FPGA). The system consists of a sensor array board, analog-to-digital converter (ADC) modules, and a processing board. The ultrasonic MEMS sensors are precisely aligned on a printed circuit board (PCB) to form a 16 × 8 planar grid with 112 ° × 50° viewing angles for wide-band signals with the center frequency at 40 KHz.

We describe a fast and accurate indoor localization technique using the multiple signal classification (MUSIC) algorithm. The MUSIC algorithm is known as a high-resolution method for estimating directions of arrival (DOAs) or propagation delays. A critical problem in using the MUSIC algorithm for localization is its computational complexity. Therefore, we devised a novel algorithm called Time Space additional Temporal-MUSIC, which can rapidly and simultaneously identify DOAs and delays of mul-ticarrier ultrasonic waves from transmitters. Computer simulations have proved that the computation time of the proposed algorithm is almost constant in spite of increasing numbers of incoming waves and is faster than that of existing methods based on the MUSIC algorithm. The robustness of the proposed algorithm is discussed through simulations. Experiments in real environments showed that the standard deviation of position estimations in 3D space is less than 10 mm, which is satisfactory for indoor localization.

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.

We describe a fast and accurate indoor localization technique using the multiple signal classification (MUSIC) algorithm. This algorithm is known as a high-resolution method for estimating directions of arrival (DOAs) or propagation delays. A critical problem in using the MUSIC algorithm for localization is its computational complexity. Therefore, we devised a novel algorithm called Time Space additional Temporal MUSIC (TSaT-MUSIC), which can rapidly and simultaneously identify DOAs and delays of multicarrier ultrasonic waves from transmitters. Computer simulations have proved that the computation time of the proposed algorithm is almost constant in spite of increasing numbers of incoming waves, and is faster than that of existing methods based on the MUSIC algorithm. Experiments in real environments showed that the standard deviation of position estimations in 3D space is less than 10 mm, which is satisfactory for indoor localization.

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.

We propose an acoustic imaging method that can achieve high resolution and high image quality. Our imaging method is based on a combination of pulse compression and the synthetic transmit aperture (STA). Conventionally, these methods have often used signals modulated with M-sequences because of their relatively good orthogonality. However, the image quality is degraded by noise in the correlations between such signals. Our proposed method addresses this issue by intentionally synthesizing signals with suppressed correlations. We devised a new method for signal synthesis, in which the sub-carrier parameters of multi-carrier signals were optimized by a genetic algorithm. The simulation results showed that the optimized signals reduced the correlation noise by 7.8dB compared to the conventional M-sequence signals. The improvement in image quality was also verified by the simulation.

We present a system that can identify positions of objects in three-dimensional space using ultrasonic communications. The proposed system uses the time of flight of ultrasonic waves to calculate the distance between a transmitter and a microphone. An innovative method called the Phase Accordance Method is used for accurate detection of the arrival time of the ultrasonic signal for distance measurements. The main benefit of the proposed system is that it can locate positions of static and moving objects in a three-dimensional space by using only one compact receiver unit mounting three ultrasonic microphones; this will reduce the users' deployment tasks. Experimental results prove that the system possesses sufficient accuracy levels and stable performance of position measurements in static and dynamic situations, even though the beacon geometry of the system is poor.

We introduce a localization system using ultrasonic signals. Our system adopts the Phase Accordance Method, which we proposed previously for accurate distance measurement [1, 2]. Unlike other ultrasonic-based systems, our system can locate ultrasonic transmitters with only one receiver, thanks to the high accuracy of the Phase Accordance Method. Thus our system can cover wider areas with fewer beacons than conventional systems, improving the scalability of the system. To evaluate the scalability and accuracy of our system, we developed a robot-tracking system and conducted an experiment with a moving robot. During the experiment, localization was executed both by our proposed method and by a conventional method based on trilateration. The experiment was repeated with different densities of receivers so that we could compare the accuracy and the scalability of our proposed method with those of the conventional method. We found that the position error of our method was degraded from 6.1 cm to 14.6 cm compared with the conventional method. However, our method improved the success rate of localization from 31% to 95%. We also conducted some localization experiments in which the robot stood still. This was because we wanted to investigate why the accuracy was degraded in the dynamic tracking. The results showed that the degradation of accuracy might be because of a systematic error in localization that is dependent on the geometric relationship between the transmitter and the receiver.

Too narrow, the productivity-oriented vision guiding ubiquitous computing should be replaced or enriched with humanistic aspects. We discuss the role of Maslow's hierarchy of needs in the creation and adoption of smart spaces, robots and wearable computers worldwide to provide elements for alternative visions of ubiquity. We show that current ubiquitous systems are stratified at the lowest levels of the hierarchy. Based on interviews, questionnaires and experiments, we highlight a positive correlation between the hierarchy of needs and the general public's perception and possible adoption of services. Finally, we discuss implications of these results, and notably the importance of creating humanistic frameworks, services and environments.

Ubiquitous computing can significantly improve the general public's quality of life worldwide from birth to old age because it allows monitoring, awareness and support in many environments thanks to sensors, actuators, remote connections, and dedicated knowledge bases. However, ageing influences its usefulness and appropriateness due to growth and decline as well as changes in activities and uses of technology. We discuss potential dedicated services with smart spaces and wearable computers based on the cognitive, physical, physiological, and sensory characteristics of young people and older adults. Our main contribution is to show that existing services support few age-specific needs, and that designs miss age-appropriate techniques, taking into account the whole life span with personal, public and shared systems.

Older adults have specific needs and abilities reflected by their decline, activities and use of technology. First, we present their cognitive, physical, physiological, and sensory characteristics, and their impact on fundamental needs. Then, we suggest and discuss dedicated systems exploiting intelligent environments to support physical and mental health, prevent falls and alert, multiply social contacts, and ensure self-esteem. Besides, proper design of arbitrary services must incorporate safety, integration, variability, senses, acceptance, and memory. Our most significant contribution is to provide the first overview of older adults' specific needs in intelligent environments.

We consider the design of a ubiquitous system that aims to strengthen affective bonds with, and to allow support for, family members, especially for distant relationships. It is based on wearable computers that evaluate emotions, health and activities, then transmit the information to authorized persons, and enable interactions. Our most significant contribution is to provide the design for an everyday life system that focuses on emotions, health and activities, and takes into account age specificities as well as emotional design.

Infants, children and adolescents have specific needs reflected by their growth, activities and use of technology. We present their cognitive, emotional, physical, physiological, sensory, and social characteristics. Based on impacts on fundamental needs, we discuss dedicated systems exploiting wearable computers and the proper design of such systems. Our most significant contribution is to provide the first overview of young people's specific needs in wearable computing.

We consider the design of a ubiquitous system whose objective is to strengthen affective bonding and allow affective support, especially for distant relationships with the family and friends. It is based on wearable computers that evaluate emotions, transmit information to authorized persons, and enable interactions. Our most significant contribution is the provision of the design for a complete system usable in everyday life, based on emotional design and on multi-cultural feedback.

We discuss the privacy issues related to the design of systems that disclose information about emotions to remote acquaintances, without simultaneous communication: users do not chat, see or hear each other. We consider the acquisition of information, storage, processing, multi-modal rendering, and interactions. We illustrate our points with the system we designed for affective bonding and support with family and friends. Our most significant contribution is the provision of a first overview of the whole process for everyday life uses.

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.

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 user's 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.

This paper examines the perception of wearable computers for everyday life by the general public, in order to foster the adoption of this technology. We present a social study that focuses on sensors, actuators, autonomy, uses, and privacy. Carried out in 2005, it considers gender and cultural disparities in two dissimilar groups: French (115 males, 59 females) and Japanese (61 males, 54 females) citizens. Acknowledging that exposition to wearables can alter perception about them, we designed a garment-shaped prototype to check our results, estimate shifts of perception, and define guidelines for equipment and services. We describe our prototype, and future experiments dealing with face-to-face contacts, community awareness, and relaxing environments.

In this paper, we describe an interactive guide system for kids in museums. The system uses a sensing board which can rapidly recognize types and locations of multiple objects, and creates an immersive environment by giving users visual and auditory feedback to their manipulations on the board. The purpose of the system is to attract users' interests in a real exhibition by allowing them to interact with the corresponding virtual exhibition on the board, and providing them with its information. We have evaluated the system in a museum. From the interviews and questionnaires, we have confirmed that it is easy for kids to use the system and it can raise their motivation for visiting real exhibitions.

This paper describes an electronically enhanced board called E 2board. The motivation of our work comes from a traditional board game, which groups of players enjoy in a face-to-face situation by manipulating pieces on a physical board. In order to enhance users’ excitement and immersiveness, a physical board and a virtual world created by a computer are linked together with E 2board. An important function of E 2board is the rapid recognition of massive numbers of different objects. The authors have developed several applications using E 2board: not only games, but also systems for supporting group activities. Some of these applications are shown.

Since most control systems software is hardware-related, real-time-oriented and complex, adaptable OSs which help program productivity and maintainability improvement are in strong demand.We are developing an adaptable and extensible OS based on micro-kernel and multi-server scheme: each server runs in a protected mode interacting only via messages, and could be added/extended/deleted easily. Since this OS is highly modularized, inter-process messaging overhead is a concern. Our implementation proved good efficiency and maintainability.

Airborne acoustic imaging has the capability of obtaining distance information of an object in a scene, the capability of distinguishing objects from the background or a texture and it can also estimate the velocity of objects. However, the nonideal radiation pattern of a transmitter used for insonifying an imaging space can degrade imaging results. In this work, radiation patterns have been investigated, and a new approach to decrease the effect of a transmitter’s radiation pattern in acoustic imaging is proposed. The novelty of our proposed method is that we used the measurement-based transmitter’s radiation compensation. The compensation can be accomplished without knowing anything about the model and characteristics of the transmitter, the receiver and the medium. We compensated for the transmitter’s radiation pattern and reconstructed acoustic images using the synthetic transmit aperture imaging technique. The compensation was based on the radiation pattern obtained from real measurements using a Wiener filter. The Wiener filter was used to compensate for the nonideal radiation pattern of the ultrasonic transmitter for both the phase and amplitude aspects simultaneously. To verify the proposed method, an indoor airborne acoustic imaging experiment was conducted using a two-dimensional (2D) receiver array and a 2D transmitter array. The results show an obvious improvement in the vertical angular resolution of the reconstructed three-dimensional images as well as a satisfactory horizontal angular resolution.