- K. Worms, C. Klamouris, F. Wegh, L. Meder, D. Volkmer, S. P. Philipps, S. K. Reichmuth, H. Helmers, A. Kunadt, J. Vourvoulakis, A. W. Bett, C. Koos, W. Freude, J. Leuthold, W. Stork
Reliable and lightning-safe monitoring of wind turbine rotor blades using optically powered sensors
In Wind Energy, 2016
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- T. Beuth, M. Fox, W. Stork
Influence of laser coherence on reference matched Laser Doppler Velocimetry
In Applied Optics, Band 55, S. 2104-2108, 2016
Zusammenfassung:
The probe length is investigated under the influence of the coherence length of Gaussian and Lorentzian spectra for the case that the focal point and the point of highest interference are matched in a strongly focused laser Doppler velocimetry setup (LDV). Isosurfaces of a −3 dB drop of the intensity maximum are estimated and suggested as an alternative, comprehensible way to define probe volumes. In the end, the equations are applied for an exemplary lidar setup to show the reduction of requirements for the coherence length of the laser source in comparison to unmatched cases.
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- T. Pozaic, U. Lindemann, A. K. Grebe, W. Stork
Sit-to-Stand Transition Reveals Acute Fall Risk in Activities of Daily Living
In IEEE Journal of Translational Engineering in Health and Medicine, Band 4, S. 1-11, 2016
Zusammenfassung:
The focus of this paper was on finding wrist sensor-derived features for detecting highly acute fall risk from the sit-to-stand transitions performed in a non-ambulatory environment. Furthermore, the influence of the dominant and non-dominant hand on these features was investigated. A cohort of 174 older subjects was monitored for seven consecutive days in their home setting by using inertial sensors attached at the wrist. Based on the reported falls during a one-month follow-up phase, two groups were defined. Twenty-one time and frequency domain features were implemented for the quantitative assessment of extracted sit-to-stand transitions. The statistical analysis yielded two features that could convincingly distinguish fallers from non-fallers for the dominant hand, and six for the non-dominant hand. A novel feature, energy of the applied support during standing up, showed statistically good performance independently of on which hand the sensor node was worn, as well as for the dominant and non-dominant hand (p <; 0.014, p <; 0.027, and p <; 0.020, respectively). This paper overcomes limitations of clinical tests and shows a reliable application of wrist-worn bands in terms of assessment of highly acute fall risk. In addition, it reveals the sit-to-stand transition as a potential assessment source for the wrist-worn devices in the elderly population. Early assessment of the risk of falling in a widely accepted and non-stigmatized manner has the ability to bring crucial changes in fall prevention strategies, reducing the number of falls and the fall rate.
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- C. Zimmermann, J. Zeilfelder, T. Bloecher, M. Diehl, S. Essig, W. Stork
Evaluation of a smart drink monitoring device
In 2017 IEEE Sensors Applications Symposium (SAS), S. 1-5, 2017
Zusammenfassung:
Liquid supply risk management done for inpatient care of the elderly or persons suffering from diseases is currently a time intensive procedure. The paper describes the design and evaluation of an automatic beverage monitoring system. An electronic device is presented, which is able to measure the fluid intake of the patient and provide an automated documentation and connection to existing software architecture. In a user-oriented study the functionality and acceptance were evaluated and the results show that drinking motivation can verifiably result in temporarily increased hydration.
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Zusammenfassung:
Liquid supply risk management done for inpatient care of the elderly or persons suffering from diseases is currently a time intensive procedure. The paper describes the design and evaluation of an automatic beverage monitoring system. An electronic device is presented, which is able to measure the fluid intake of the patient and provide an automated documentation and connection to existing software architecture. In a user-oriented study the functionality and acceptance were evaluated and the results show that drinking motivation can verifiably result in temporarily increased hydration.
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- J. Schneider, M. Schroth, M. Holzhey, T. Blöcher, W. Stork
An approach to improve impedance plethysmography on the wrist by using adaptive feedback control
In 2017 IEEE Sensors Applications Symposium (SAS), S. 1-6, 2017
Zusammenfassung:
The growing market of wearable devices made ambulant vital sign monitoring popular in recent years. Impedance plethysmography (IPG) provides a promising low power solution for detecting pulse waves and respiration by measuring the impedance of blood vessels at the wrist. However, the measurement principle makes high demands on the analog front end, due to low signal-to-noise ratio (SNR) and unknown measurement conditions. In this paper an approach to apply impedance plethysmography is presented. The proposed circuit is based on the impedance measurement IC AD5933 and an adaptive feedback control to regulate current injection and measuring amplification in order to adjust the optimal operating point. Experimental studies demonstrate the potential of the system as promising technology for continuous vital sign monitoring on the wrist.
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Zusammenfassung:
The growing market of wearable devices made ambulant vital sign monitoring popular in recent years. Impedance plethysmography (IPG) provides a promising low power solution for detecting pulse waves and respiration by measuring the impedance of blood vessels at the wrist. However, the measurement principle makes high demands on the analog front end, due to low signal-to-noise ratio (SNR) and unknown measurement conditions. In this paper an approach to apply impedance plethysmography is presented. The proposed circuit is based on the impedance measurement IC AD5933 and an adaptive feedback control to regulate current injection and measuring amplification in order to adjust the optimal operating point. Experimental studies demonstrate the potential of the system as promising technology for continuous vital sign monitoring on the wrist.
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- T. Blöcher, J. Schneider, M. Schinle, W. Stork
An online PPGI approach for camera based heart rate monitoring using beat-to-beat detection
In 2017 IEEE Sensors Applications Symposium (SAS), S. 1-6, 2017
Zusammenfassung:
In this work an online method for camera-based heart rate detection, also known as Photoplethysmography Imaging (PPGI), is presented. The pulse related signal is obtained from RGB videos of the human face, using an off the shelf camera under ambient light conditions. The algorithm for heart rate estimation is based on the beat-to-beat analysis of the PPGI signal, allowing the estimation of psychophysiological parameters like the heart rate variability. The system is tested indoors under laboratory conditions, and in field trials integrated in a car. Field tests are done as a step towards robust appraisal of psycho-physiological driver states. In measurements with eight subjects, a sensitivity of ~93% for pulse peak detection is reached under resting and constant light conditions. First test drives show good results for heart rate estimation while driving on highways outside of city traffic. The results indicate that PPGI can be a suitable solution for providing vital sign information of drivers in cars.
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Zusammenfassung:
In this work an online method for camera-based heart rate detection, also known as Photoplethysmography Imaging (PPGI), is presented. The pulse related signal is obtained from RGB videos of the human face, using an off the shelf camera under ambient light conditions. The algorithm for heart rate estimation is based on the beat-to-beat analysis of the PPGI signal, allowing the estimation of psychophysiological parameters like the heart rate variability. The system is tested indoors under laboratory conditions, and in field trials integrated in a car. Field tests are done as a step towards robust appraisal of psycho-physiological driver states. In measurements with eight subjects, a sensitivity of ~93% for pulse peak detection is reached under resting and constant light conditions. First test drives show good results for heart rate estimation while driving on highways outside of city traffic. The results indicate that PPGI can be a suitable solution for providing vital sign information of drivers in cars.
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