Yo Kato

Development of a nursing-care assistant robot RIBA that can lift a human in its arms

In aging societies, there is a strong demand for robotics to tackle problems caused by the aging population. Patient transfer, such as lifting and moving a bedridden patient from a bed to a wheelchair and back, is one of the most physically challenging tasks in nursing care, the burden of which should be reduced by the introduction of robot technologies. We have developed a new prototype robot named RIBA with human-type arms that is designed to perform heavy physical tasks requiring human contact, and we succeeded in transferring a human from a bed to a wheelchair and back. To use RIBA in changeable and realistic environments, cooperation between the caregiver and the robot is required. The caregiver takes responsibility for monitoring the environment and determining suitable actions, while the robot undertakes hard physical tasks. The instructions can be intuitively given by the caregiver to RIBA through tactile sensors using a newly proposed method named tactile guidance. In the present paper, we describe RIBAs design concept, its basic specifications, and the tactile guidance method. Experiments including the transfer of humans are also reported.

Temperature-dependent dynamic response enables the qualification and quantification of gases by a single sensor

We propose a new gas sensor which obtains information from a non-linear time-dependent response. We have measured the time-dependent conductance of a sensor element for various gases, such as methane, carbon monoxide, hydrogen and butane, under periodic pulse heating at 1 s intervals. Using a small ‘print type’ SnO2 sensor, we are able to observe rapid and ‘steady’ responses with high reproducibility under fixed conditions for the sample gas. With this technique, various gas species can be distinguished and quantified. We also describe an appropriate method for processing data from the time-dependent response accompanying the change of temperature.

Toward the realization of an intelligent gas sensing system utilizing a non-linear dynamic response

Abstract We report on a trial to construct an intelligent gas sensing system based on the information embedded in a non-linear dynamic response, an application that has possibilities for various kinds of practical usage. By applying a sinusoidal voltage to a heater attached to SnO 2 , a characteristic time-dependent trace of the sensor resistance is obtained as a response to environmental gases. In order to evaluate the characteristic response in a quantitative manner, Fast Fourier Transform (FFT) is performed for the dynamic response. Higher harmonics, obtained by performing the FFT, were processed using an Artificial Neural Network (ANN). It is shown that with these procedures one can simultaneously distinguish and quantify individual gas components. Actually, we show that eight different gases (methanol, ethanol, acetone, diethyl ether, benzene, iso -butane, ammonia and ethylene) as well as natural air can be identified with a single sensor, and can also be quantified with an accuracy of less than 30%. It has been confirmed that our system exhibits long-term reproducibility, and the ability for discrimination and quantification.

A Soft Human-Interactive Robot RI-MAN

Our goal is to create advanced engineering systems such as a soft human interactive robot. The robot developed here is named RI-MAN. RI-MAN exhibits the skill and ability to realize human care and welfare tasks. RI-MAN can search out a specific person in real time by fuing audio and visual information, and understand human speech based on a sound recognition function. In addition, RI-MANs body is coverd with soft touch sensors, and RI-MAN can react to the amplitude and location of external forces. Using all these sensor functions, RI-MAN can successfully follow human commands and hold up a dummy of the same size as an adult human. RI-MAN will become an invaluable partner robot.

Tactile Sensor without Wire and Sensing Element in the Tactile Region Based on EIT Method

We propose a novel soft areal tactile sensor made of pressure-sensitive conductive rubber, the principle of which is based on the inverse problem theory. The significant feature of this sensor is that it needs neither wire nor sensing element in the tactile region, because the distribution of applied pressure relating to the resistivity change in the tactile region can be estimated using electrical impedance tomography (EIT). This method enables us to make a very simple tactile sensor free from problems of wire breaks and electrodes peeling off from the rubber. The results of experiments with a have proved its effectiveness. We also discuss our computation technique to reconstruct stable pressure distribution by using the least squares method.

DYNAMIC INFORMATION PROCESSING IN NATURAL AND ARTIFICIAL OLFACTORY SYSTEMS

A new strategy for building artificial gas sensing systems is suggested based on knowledge of the dynamic response mechanism of the olfactory system. Difficulties with the processing of time-dependent inputs by neural networks are discussed.

Fast and Accurate Tactile Sensor System for a Human-Interactive Robot

With the advent of the aging society, the demand for nursing care for the elderly is becoming much larger. The application of robotics to helping on-site caregivers is consequently one of the most important new areas of robotics research. Such humaninteractive robots, which share humans’ environments and interact with them, should be covered with soft areal tactile sensors for safety, communication, and dextrous manipulation. Tactile sensors have interested many researchers and various types of tactile sensors have been proposed so far. Many tactile sensors have been developed on the basis of microelectro-mechanical system (MEMS) technology (for example, (Suzuki, 1993; Souza & Wise, 1997)). They have a high-density and narrow covering area realized by applying MEMS technology, and as a result, are not suitable for covering a large area of a robot’s surface. Some tactile sensors suitable for use on robot fingers or grippers have also been developed (Nakamura & Shinoda, 2001; Yamada et al., 2002; Shimojo et al., 2004). Many of them have the ability to detect tangential stress and can be used in grasping force control. Their main target is robot fingers, and consequently they were not designed to cover a large area. There are also commercially available tactile sensors such as those offered by Tekscan (Tekscan, 2008) based on pressure-sensitive ink or rubber, and KINOTEXTM tactile sensors (Reimer & Danisch, 1999) utilizing the change in the intensity of light scattered by the covering urethane foam when deformed. However, they are not sufficiently accurate because of strong hysteresis and creep characteristics. The idea of covering a large area of a robot’s surface with soft tactile skinlike sensors is attracting researchers (Lumelsky et al., 2001). Some human-interactive robots for which a large area of their surface is covered with soft tactile sensors have actually been developed (Inaba et al. 1996; Tajima et al. 2002; Kanda et al. 2002; Mitsunaga et al. 2006; Ohmura et al., 2006; Ohmura & Kuniyoshi, 2007). However, the tactile sensors are not suitable for humaninteractive robots, particularly when physical labor using tactile sensation is required. For example, one tactile sensor in (Tajima et al. 2002) has only 3 values as its output, and another tactile sensor in (Tajima et al. 2002) is gel-type and cannot be used over a long period because of the evaporation of the contained water. The tactile sensor in (Mitsunaga et al. 2006) has only 56 elements in total. Flexible fabric-based tactile sensors using an electrically conductive fabric have also been proposed for covering a robot (Inaba et al. 1996), but the O pe n A cc es s D at ab as e w w w .in te ch w eb .o rg

Tactile Sensor Without Wire and Sensing Element in the Tactile Region Using New Rubber Material

Recently the idea of covering a robots surface with a ‘skin’ of soft tactile sensors has attracted the attention of researchers, and some human-interactive robots covered with such sensors have actually been made (Tajima et al., 2002; Kanda et al., 2002). However, most conventional tactile sensors need a large number of sensing elements and wires because every detection point needs one sensing element and wiring to an A/D converter. There are some studies aiming to overcome this wiring problem by using 2D surface communication or wireless communication (Shinoda & Oasa, 2000; Ohmura et al., 2006), but these are very complicated and expensive solutions. We have developed a soft areal tactile sensor made of pressure-sensitive conductive rubber without any wire or sensing element in the tactile region. The distribution of applied pressure, relating to the resistivity change of the pressure-sensitive rubber, can be estimated by using inverse problem theory. We employed electrical impedance tomography (EIT) to reconstruct the resistivity distribution from information obtained by electrodes placed around the region. EIT is an established method in medical and industrial applications (Holder, 2005), but it has not been applied to tactile sensors until recently. Nagakubo and Alirezaei proposed a tactile sensor using an EIT algorithm operating with commonly used EIT software and commercially available pressure-sensitive rubber (Nagakubo & Kuniyoshi, 2006; Alirezaei et al., 2006). Their method is based on the same principle as ours, but their pressure-sensitive conductive rubber is not suitable for this method. We have newly developed special pressure-sensitive conductive rubber for this sensor, and adopted a new computation technique suitable for this rubber. We have also developed a prototype sensor system that can measure pressure distribution in real-time. In this paper, we describe basic structure and computation technique of our sensor system, as well as experimental results obtained using our prototype sensor system.

Determination of locations on a tactile sensor suitable for respiration and heartbeat measurement of a person on a bed.

Sleep monitoring systems that can be used in daily life for the assessment of personal health and early detection of diseases are needed. To this end, we are developing a system for unconstrained measurement of the lying posture, respiration and heartbeat of a person on a soft rubber-based tactile sensor sheet. The respiration and heartbeat signals can be detected from only particular locations on the tactile sensor, and the locations depend on the lying location and posture of the measured person. In this paper, we describe how to determine the measurement locations on the sensor. We also report a realtime program that detects the respiration rate and the heart rate by using this method.

MEASUREMENT OF RESPIRATION AND HEARTBEAT USING A FLEXIBLE TACTILE SENSOR SHEET ON A BED

We describe a measurement method of respiration and heartbeat using a Smart Rubber sensor, a rubber-based flexible tactile sensor sheet that we developed. This method is useful for unconstrained recording of a person sleeping soundly, sleeping lightly, lying down, sitting on a bed, and so on. Our goal is to monitor those who require nursing care. The proposed method measures respiration and heartbeat as follows. First, we measure body pressure by using the Smart Rubber sensor placed on a bed. Then, the method applies a frequency analysis to the time series data of body pressure. Finally, respiration and heartbeat are obtained by extracting suitable frequency bands. In the experiments, we show that respiration and heartbeat are successfully measured.