Helmut Beikirch

A wearable multi-sensor system for mobile acquisition of emotion-related physiological data

Interest in emotion detection is increasing significantly. For research and development in the field of Affective Computing and emotion-aware interaction techniques, reliable and robust technology is needed for detecting emotional signs in users under everyday conditions. In this paper, a novel wearable system for measuring emotion-related physiological parameters is presented. Currently heart rate, skin conductivity, and skin temperature are taken; further sensors can easily be added. The system is very easy to use, robust, and suitable for mobile and long-time logging of data. It has an open architecture and can easily be integrated into other systems or applications. The system is designed for use in emotion research as well as in everyday affective applications.

RSSI-based indoor positioning using diversity and Inertial Navigation

A substantial criterion with the use of wireless communication is the missing location information of the mobile participants. The RSSI (Received Signal Strength Indicator)-based localization technique is an easy and well known method to predict the position of an unknown node in indoor environments whereas additional measures are required for a sufficient accuracy. The distance-pending path loss is affected by strong variations, especially appearing as frequency specific signal dropouts. A diversity concept with redundant data transmission in different frequency bands can reduce the dropout probability. Not only the availability of the communication and the positioning, but also the accuracy of the localization can be increased by the diversity concept. Another improvement can be reached by a sensor fusion of the RSSI-based position data with an Inertial Navigation System. First experimental results with miniaturized transceiver prototypes show that a good performance for precision and availability can also be reached with low infrastructural costs.

Analysis of RSS-based location estimation techniques in fading environments

Distance estimation techniques based on RSS (received signal strength) measurements put low demand on the hardware and software complexity of the infrastructure components. Based on several distance calculations a location estimation algorithm is used to compute the position of an unknown node. The algorithms differ in their complexity, expressed by the need of computation time, and in the achievable accuracy of the position estimation. Experimental results in a real life indoor scenario with 2.4 GHz RF transceivers and multipath fading channels show that an approximative location estimation algorithm like an extended centroid localization method can reach a higher accuracy than an exact mathematic least squares approach, even though the resource-aware centroid localization method has a significant lower complexity than the least squares approach.

RSSI-based indoor localization using antenna diversity and plausibility filter

Distance estimation by the evaluation of RSSI measurements is an easy method to predict the position of an unknown node. Therefore common and proven systems can be used for the infrastructure. For indoor environments the distance-pending path loss is affected by strong variations, especially appearing as frequency specific signal dropouts. A diversity concept with redundant data transmission in different frequency bands can reduce the dropout probability. When also space diversity and plausibility filtering are used, the Location Estimation Error can be reduced significantly. The investigations show that a good performance for precision and availability can also be reached with low infrastructural costs.

Recording electric potentials from single adherent cells with 3D microelectrode arrays after local electroporation

This short communication reports on the innovative method of the local micro-invasive needle electroporation (LOMINE) of single adherent cells. The investigation of cellular reactions in living cell cultures represents a fundamental method, e.g. for drug development and environmental monitoring. Existing classical methods for intracellular measurements using, e.g. patch clamp techniques are time-consuming and complex. Present patch-on-chip systems are limited to the investigation of single cells in suspension. Nevertheless, the most part of the cells of the human body is adherently growing. Therefore, we develop a new chip system for the growth of adherent cells with 64 micro-structured needle electrodes as well as 128 dielectrophoretic electrodes, located within a measuring area of 1 mm(2). With this analytical chip, the intracellular investigation of electro-chemical changes and processes in adherently growing cells will become possible in the near future. Here, we present first intracellular measurements with this chip system.

Redundancy approach to increase the availability and reliability of radio communication in industrial automation

By the use of radio communication in industrial environments the influence of multi-path propagation is a fundamental problem especially for safety-related applications. The prevailing locally variation of field strength is hardly predictable and continuously changing. A conception with a wireless redundant data transmission was developed as an approach to reduce the problematic influences. A lot of preliminary investigations in real test environments with different ISM-Radio bands are necessary for this concept. A combination of space and frequency diversity was indicated as a most suitable solution. With this multiple radio channel concept a remarkable improvement of the availability of the radio link can be achieved.

Hybrid indoor tracking with Bayesian sensor fusion of RF localization and inertial navigation

The reliable tracking of humans and materials in indoor scenarios is an ongoing research issue. For example, the monitoring of humans in partially hazardous environments — like the surroundings of an underground longwall mining infrastructure — is crucial to save human lives. A centroid location estimation technique based on received signal strength (RSS) readings offers a well known and low-cost tracking solution in such a rough environment where many other systems with optical, magnetical or ultrasound sensors fail. Due to signal fading the RSS values alone can not ensure a precise tracking. The sensor fusion of the RSS-based localization with an inertial navigation system (INS) leads to a more precise tracking. The longterm stability of the RSS-based localization and the good short-term accuracy of the INS are combined using a Kalman filter. The experimental results on a motion test track show that a tracking of humans in multipath environments is possible with low infrastructural costs.

Powerline communications interface in CSMA/CA-networks

The utilization of existing powerlines for communication purposes opens many possibilities, which can be advantageous for a wide range of field bus applications. Known home automation solutions have low transmission speeds (e.g. EIB, LON) or works with other packet-oriented communication techniques (OFDM- or TDMA-based technologies). Networks with CSMA/CA access (e.g. SCAN) requires minimized signal delay times because this delay limits the possible transmission speed. CAN systems can be used for real-time applications and are especially time-critical. They work with bit-oriented arbitration mechanisms and are composed of protocol frames (acknowledge-flag set from other bus nodes in the same frame). Therefore, the maximum delay time on the transmission and receive path must be smaller than a half bit time. This hard timing requirement causes big problems during the realization of CAN powerline transceivers. Another requirement beside the global goal of real-time capability is the development of cost- and expenditure-minimized transceivers.

Physiological Sensing for Affective Computing

Sensing affective states is a challenging undertaking and a variety of approaches exist. One of the oldest but yet often neglected way is to observe physiological processes related to sympathetic activity of the autonomic nervous system. A reason for physiological measurements not being used in emotion-related HCI research or affective applications is the lack of appropriate sensing devices. Existing systems often don’t live up to the high requirements of the real life in which such applications are to be used. This chapter starts with a short overview of the physiological processes affective applications rely on today, and commonly used techniques to access them. After this, requirements of affective applications for physiological sensors are worked out. A design concept meeting the requirements is drawn and exemplary implementations including evaluation results are described.

Device-free localization using redundant 2.4 GHz radio signal strength readings

Radio-based device-free localization (DFL) for indoor environments are based on signal anomalies due to obstacles on the line-of-sight (LOS) between previously applied reference nodes. They take use of radio signal strength (RSS) attenuation (radio tomographic imaging, RTI) or variations caused by shadowing and small-scale fading effects. An advanced methodology using redundant RSS information for each pair of reference nodes is proposed. The method uses a moving RSS variance estimator and antenna diversity with four uncorrelated 2.4 GHz radio channels to predict the users position. With the redundant RSS values the accuracy of user detection is increased by more than 50 % while the number of false positives is reduced to zero. Tracking results in a hallway test bed illustrate the behavior and improvements of the applied redundant sensor technique.