Kazuya Matsuo, Toshiharu Mukai, Yo Kato, Atsuki Shimizu, Shijie Guo
View Full Paper
 Statistics Bureau, Ministry of Internal Af-fairs and Communications, Japan: “The 2010Population Census of Japan,” Available from(Last Checked: 7 Mar.,2014).
 National Institute of Population and Social Se-curity Research: “Population Projections forJapan (January 2012) -2011 to 2060-,” Availablefrom (LastChecked: 7 Mar., 2014).
 Ministry of Health, Labour and Welfare, Japan:“General Welfare and Labour,” Available from(LastChecked: 7 Mar., 2014).
 Ministry of Economy, Trade and Industry and Min-istry of Health, Labor and Welfare, Japan: “Pri-ority Areas to Which Robot Technology Is toBe Introduced in Nursing Care of the Elderly,”Available from (Last Checked: 7 Mar., 2014).
 A. Rechtschaﬀen and A. Kales: “A Manual of Stan-dardized Terminology, Techniques and Scoring Sys-tem for Sleep Stages of Human Subjects,” Bethesda,Md.: U.S. Dept. of Health, Education, and Wel-fare, Public Health Services-National Institutes ofHealth, National Institute of Neurological Diseasesand Blindness, Neurological Information Network,1968.
 Y. Kurihara and K. Watanabe: “Sleep-Stage DecisionAlgorithm by Using Heartbeat and Body-MovementSignals,” IEEE Trans. on Systems, Man, and Cyber-netics, Part A, Vol. 42, No. 6, pp. 1450–1459, 2012.62on his back on his stomach on his sideFigure 7. Frequency spectrums of the three postures by applying the FFT to the body pressure for measuring respiration. Thethree postures are lying on his back, on his stomach, and on his side. The horizontal axes represent the frequency range from 0to 2 [Hz]. The vertical axes represent the amplitude spectrum.on his back on his stomach on his sideFigure 8. Measurement results of respiration of the three postures. The blue lines indicate the respiratory waveform obtainedby our method. The red lines indicate the output value of the respiratory sensor.
 Y. Kambayashi and H. Hagiwara: “Estimating SleepCycle Using Body Movement Density,” Proc. of the2012 5th Int’l Conf. on Biomedical Engineering andInformatics, pp. 1029–1033, 2012.
 S. Okada, Y. Ohno, Goyahan, K. Kato-Nishimura,I. Mohri, and M. Taniike: “Examination of Non-Restrictive and Non-Invasive Sleep Evaluation Tech-nique for Children Using Diﬀerence Images,” Proc.of the 30th Annual Int’l Conf. of the IEEE Engineer-ing in Medicine and Biology Society, pp. 2483–2487,2008.
 R. M. Harper, V. L. Schechtman, and K. A. Kluge:“Machine Classiﬁcation of Infant Sleep State Us-ing Cardiorespiratory Measures,” Electroencephalog-raphy and Clinical Neurophysiology, Vol. 67, No. 4,pp. 379–387, 1987.
 Y. Kurihara and K. Watanabe: “Development ofUnconstrained Heartbeat and Respiration Measure-ment System with Pneumatic Flow,” IEEE Trans. onBiomedical Circuits and Systems, Vol. 6, No. 6, pp.596–604, 2012.
 J. Alihanka, K. Vaahtoranta, and I. Saarikivi: “A NewMethod for Long-term Monitoring of the Ballisto-cardiogram, Heart Rate, and Respiration,” AmericanJournal of Physiology - Regulatory, Integrative andComparative Physiology, Vol. 240, No. 5, R384–392,1981.
 Z. T. Beattie, C. C. Hagen, and T. L. Hayes: “Clas-siﬁcation of Lying Position Using Load Cells Underthe Bed,” Proc. of the 33rd Annual Int’l Conf. of theIEEE Engineering in Medicine and Biology Society,pp. 474–477, 2011.
 Y. Nishida, M. Takeda, T. Mori, H. Mizoguchi, andT. Sato: “Unrestrained and Non-invasive Monitor-ing of Human’s Respiration and Posture in Sleep Us-ing Pressure Sensors,” Journal of the Robotics Soci-ety of Japan, Vol. 16, No. 5, pp. 705–711, 1998 (inJapanese).
 J. W. Cooley and J. W. Tukey: “An Algorithm forthe Machine Calculation of Complex Fourier Series,”Mathematics of Computation, Vol. 19, No. 90, pp.297–301, 1965.
 C. F. Gauss: “Nachlass: Theoria Interpolatio-nis Methodo Nova Tractata,” Carl Friedrich GaussWerke, Band 3, Koniglichen Gesellschaft der Wis-senschaften, Gottingen, pp. 265–327, 1866.
 S. Guo, Y. Kato, H. Ito, and T. Mukai: “Devel-opment of Rubber-Based Flexible Sensor Sheet forCare-Related Apparatus,” Sumitomo Electric Indus-tries Technical Review, No. 75, pp. 125–131, 2012.
 R. Cork: “XSENSOR Technology: a Pressure Imag-ing Overview,” Sensor Review, Vol. 27, No. 1, pp. 24–28, 2007.