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Automatic Localization of an Ultrasound Probe with the Help of Magnetic Sensors

Current Directions in Biomedical Engineering 2022年第2期8卷 317-320页

作者： Bald, Christin Bergholz, Robert Schmidt, Gerhard Digital Signal Processing and System Theory Institute of Electrical Engineering and Information Technology Faculty of Engineering Christian-Albrechts-Universität zu Kiel Kaiserstraße 2 Kiel Germany Digital Signal Processing and System Theory Institute of Electrical Engineering and Information Technology Faculty of Engineering Christian-Albrechts-Universität zu Kiel Kiel Germany Pediatric Surgery Faculty of Medicine Christian-Albrechts-Universität zu Kiel Kiel Germany

Ultrasound measurements are a widely used instrument in clinical practice. For later traceability of the images, the position (and orientation) of the ultrasound probe must be recorded during the measurement. Until now this has to be done manually by the physician. An easier and more accurate approach would be the automatic tracking of the ultrasound probe. This contribution shows a first approach for automatically localizing the ultrasonic head during measurement. The proposed method is based on coils surrounding the patient bed and a 3D magnetic sensor placed on the ultrasound head. Besides some pre- and postprocessing steps, the proposed localization algorithm is based on trilateration followed by a least mean squares approach for refinement of the estimation. In a first proof-of-concept measurement with fixed positions and orientations of the ultrasound head a mean accuracy of 2.85 cm and 8.94 was achieved. Additionally, a measurement with a moving ultrasound head is presented to demonstrate the real-time capability of the system. Finally, future steps for improving the automatic measurement are discussed, including a graphical user interface for the physician and the use of magnetoelectric sensors for measurement. © 2022 The Author(s), published by De Gruyter.

关键词： Ultrasonics

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Model-based Tracking of Magnetic Sensor Gloves in Real Time

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Current Directions in Biomedical Engineering 2023年第1期9卷 85-88页

作者： Schmidt, Gerhard Boueke, Moritz Hoffmann, Johannes Schmidt, Tobias Bald, Christin Bergholz, Robert Digital Signal Processing and System Theory Department of Electrical and Information Engineering Faculty of Engineering Kiel University Kaiserstr. 2 Kiel 24143 Germany Department of Electrical and Information Engineering Faculty of Engineering Kiel University Kiel Germany Department of Pediatric Surgery Faculty of Medicine Kiel University Kiel Germany

While mechanical tracking is commonly seen in robot-Assisted surgery, contactless gesture control leads to a more intuitive approach. Magnetic localization systems might be able to provide an untethered access to the necessary hand movement data. A model-based system exploiting a priori knowledge to improve the accuracy and robustness can be beneficial in this context. We present a proof of concept, in which the index finger of a digital twin of a hand is tracked with three simulated sensors. Based on the physiological composition, the finger is modeled as a kinematic chain with rotational degrees of freedom between the segments according to the corresponding finger joints. We applied an extended Kalman filter using this description to enhance position and rotation estimates for the sensors on the finger segments. We achieved mean absolute errors © 2023 the author(s), published by Walter de Gruyter Berlin/Boston.

关键词： Degrees of freedom (mechanics)

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Mixed Analog-digital Speech Communication for Underwater Applications 14

Mixed Analog-digital Speech Communication for Underwater App...

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14th ITG Conference on Speech Communication

作者： Wisch, Tim Owe Schmidt, Gerhard Digital Signal Processing and System Theory CAU Kiel Kiel Germany

ISBN: (纸本)9783800756285

In some cases, a speech communication link is necessary in underwater environments. While in terms of data communication advanced techniques are investigated and employed, mostly traditional (analog) forms of speech transmission are used for speech communication (at least in commercial products). In this contribution we present a mixed analog-digital approach, that tackles this problem by combining digital and analog approaches. Both transmission paths rely on each other in order to lower the necessary bitrate for the digital part and enhance the signal properties of the analog part. The proposed transmission scheme uses linear predictive coding (LPC) filtering combined with a codebook to whiten the input speech. Afterwards, the resulting signal is power normalized and transmitted in the analog transmission part and the quantized normalization factor is transmitted together with the codebook index in the digital transmission part. This leads to an analog transmission signal which is strongly reduced in dynamics. © VDE VERLAG GMBH ∙ Berlin ∙ Offenbach.

关键词： Speech communication

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Impact of a Speaker Head Rotation on the Far-end Listening Situation 14

Impact of a Speaker Head Rotation on the Far-end Listening S...

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14th ITG Conference on Speech Communication

作者： Hübschen, Tobias Al-Mafrachi, Rasool Schmidt, Gerhard Digital Signal Processing and System Theory Kiel University Kiel Germany

ISBN: (纸本)9783800756285

Speech communication and dialog systems inside vehicles are usually optimized for a speaker in the driver’s seat who is permanently facing forward. However while driving, a speaker does repeatedly rotate his head left and right, which changes the properties of the signal picked up by the microphone. This work analyzes to what extent such a speaker head rotation impacts the signal in terms of frequency content, listening quality, and listening effort. By presenting a simple method for compensating the rotation effects and by combining this method with noise reduction and band limitation of the signals, an analysis of the far-end listening situation with and without speaker head rotation compensation is achieved. © VDE VERLAG GMBH ∙ Berlin ∙ Offenbach.

关键词： Speech communication

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Automatic Localization of an Ultrasound Probe with the Help of Magnetic Sensors

Automatic Localization of an Ultrasound Probe with the Help ...

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Ultrasound measurements are a widely used instrument in clinical practice. For later traceability of the images, the position (and orientation) of the ultrasound probe must be recorded during the measurement. Until now this has to be done manually by the physician. An easier and more accurate approach would be the automatic tracking of the ultrasound probe. This contribution shows a first approach for automatically localizing the ultrasonic head during measurement. The proposed method is based on coils surrounding the patient bed and a 3D magnetic sensor placed on the ultrasound head. Besides some pre- and postprocessing steps, the proposed localization algorithm is based on trilateration followed by a least mean squares approach for refinement of the estimation. In a first proof-of-concept measurement with fixed positions and orientations of the ultrasound head a mean accuracy of 2.85 cm and 8.94◦ was achieved. Additionally, a measurement with a moving ultrasound head is presented to demonstrate the real-time capability of the system. Finally, future steps for improving the automatic measurement are discussed, including a graphical user interface for the physician and the use of magnetoelectric sensors for measurement. © 2022 The Author(s), published by De Gruyter.

关键词： Ultrasonics

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Model-based Tracking of Magnetic Sensor Gloves in Real Time

Model-based Tracking of Magnetic Sensor Gloves in Real Time

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作者： Schmidt, Gerhard Boueke, Moritz Hoffmann, Johannes Schmidt, Tobias Bald, Christin Bergholz, Robert Digital Signal Processing and System Theory Department of Electrical and Information Engineering Faculty of Engineering Kiel University Kaiserstr. 2 Kiel24143 Germany Department of Electrical and Information Engineering Faculty of Engineering Kiel University Kiel Germany Department of Pediatric Surgery Faculty of Medicine Kiel University Kiel Germany

关键词： Degrees of freedom (mechanics)

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Robust and High Gain Acoustic Feedback Compensation in the Frequency Domain With a Simple Energy-decay Operator 14

Robust and High Gain Acoustic Feedback Compensation in the F...

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14th ITG Conference on Speech Communication

作者： Linhard, Klaus Bulling, Philipp Gimm, Marco Schmidt, Gerhard Digital Signal Processing and System Theory Kiel University Kiel Germany Cerence Ulm Germany

ISBN: (纸本)9783800756285

Acoustic feedback compensation in speech applications often suffers from an insufficient adaptation. As a result feedback whistling may be audible and the compensation gain and generally the speech quality is limited. In this work, we introduce the concept of an energy-decay operator and show how to use it for tap-selective step-size control of a multi-delay frequency-domain filter (MDF). Therefore, we derive a so-called "complex sign-sign algorithm" with an inherently included decay operator. Finally, we show robust simulation results with high amplification although the used algorithm shows very low complexity. Possible applications are in-car communication (ICC) systems or other sound reinforcement applications. © VDE VERLAG GMBH ∙ Berlin ∙ Offenbach.

关键词： Feedback

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A Concept for Myocardial Current Density Estimation with Magnetoelectric Sensors

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Current Directions in Biomedical Engineering 2023年第1期9卷 89-92页

作者： Schmidt, Gerhard Engelhardt, Erik Elzenheimer, Eric Hoffman, Johannes Schmidt, Tobias Zaman, Adrian Frey, Norbert Digital Signal Processing and System Theory Institute of Electrical Engineering and Information Technology Faculty of Engineering Kiel University Kaiserstr. 2 Kiel 24143 Germany Medical Department III Specialised in Cardiology and Angiology University Medical Center Schleswig-Holstein Arnold-Heller-Str. 3 / House K3 Kiel 24105 Germany Internal Medicine III: Heart Vascular and Lung University Medical Center Heidelberg Im Neuenheimer Feld 410 Heidelberg 69120 Germany

In this paper we present a novel noninvasive approach to estimate current densities in the heart from magnetocardiography. The proposed algorithm uses nested optimization to model current densities in equally-sized voxels of myocardial tissue. First-order Thiran all-pass filters are used to describe the propagation between *** demonstrate feasibility of the algorithm for a noise-free single-layer simulation. However, challenges remain, such as addressing measurement noise and optimizing propagation velocity. Overall, this approach has the potential to complement or replace invasive catheter-based electrophysiological studies for localization of arrhythmogenic tissue. © 2023 the author(s), published by Walter de Gruyter Berlin/Boston.

关键词： Magnetocardiography

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A Concept for Myocardial Current Density Estimation with Magnetoelectric Sensors

A Concept for Myocardial Current Density Estimation with Mag...

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作者： Schmidt, Gerhard Engelhardt, Erik Elzenheimer, Eric Hoffman, Johannes Schmidt, Tobias Zaman, Adrian Frey, Norbert Digital Signal Processing and System Theory Institute of Electrical Engineering and Information Technology Faculty of Engineering Kiel University Kaiserstr. 2 Kiel24143 Germany Medical Department III Specialised in Cardiology and Angiology University Medical Center Schleswig-Holstein Arnold-Heller-Str. 3 / House K3 Kiel24105 Germany Internal Medicine III: Heart Vascular and Lung University Medical Center Heidelberg Im Neuenheimer Feld 410 Heidelberg69120 Germany

关键词： Magnetocardiography

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Observations from a simple vocal-tract-model's behaviour for pd-dysarthric speech: Applicability 13

Observations from a simple vocal-tract-model's behaviour for...

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13th ITG Conference on Speech Communication

作者： Heute, Ulrich Schmidt, Gerhard Dig. Signal Processing and System Theory Faculty of Engineering CAU KielD-24143 Germany

ISBN: (纸本)9783800747672

The uniform-element tube model of a speaker's vocal tract is a by-product from LPC speech analysis. It is used here to observe a speaker's articulation. The aim is an insight into possible articulatory weaknesses of PD (Parkinson-Disease) patients who suffer from dysarthria, i.e., speaking problems. Approved auditive methods exist for evaluation of the patients' speech handicaps, applying also instrumental signal features. But a direct view on vocal-tract movements can be an additional diagnostic aid. Due to its real-time potential, the simple estimation of vocal-tract areas from LPC analysis is regarded here, despite its known impreciseness. In a first measurement set, it is checked with fluent speech of healthy persons, whether any reaction appears on articulatory changes between clear and intentionally mumbled speech. Then, with sustained vowels of healthy and slightly as well as strongly handicapped speakers, the potential of the approach to display such differences is examined. © VDE VERLAG GMBH ∙ Berlin ∙ Offenbach

关键词： Speech

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