Sebastian J. F. Fudickar

KopAL – A Mobile Orientation System for Dementia Patients

In the aging sectors of societies in the western world, dementia and its characteristics such as disorientation and obliviousness are becoming a significant problem to an increasing number of people and health systems. In order to enable such dementia patients to regain a self-determined life, we have developed a mobile orientation system with a focus on minimal operational costs and a speech based human computer interface. This system assists dementia patients in everyday problems, such as remembering appointments and staying on track within their familiar surroundings as well as informing caretakers in critical situations.

Fall-detection simulator for accelerometers with in-hardware preprocessing

Mobile fall-detection systems that use accelerometers (as the ADXL 345) with data pre-processing capabilities, enable processors to remain longer in low power modes and therefore can achieve extended device lifetimes. Since fall-detection on these accelerometers is partially executed in hardware, the development and comparison of fall-detection algorithms requires direct evaluation on the hardware and increases complexity. We introduce a fall-detection simulator for the development and comparison of fall-detection algorithms for accelerometers with and without partial in-hardware pre-processing. In addition comprehensive records of fall-situations and daily living activities were generated for the simulator from recording movements. With the help of the simulator, the sensitivity of a given fall-detection algorithm could be improved from 33% to 93%.

An energy efficient mobile device for assisted living applications

Common problems of many elderly include falling accidents and getting lost while leaving their common surroundings unattended. We developed a mobile device that includes indoor localization based on the energy-efficiency Sub 1GHz wireless communication via radio signal strength (RSS) measurements and fall detection functionality. Power management is a critical part for the success of such a device. The authors suggest the use of Sub 1GHz transceivers (using the 433, 868 or 915 MHz frequency bands) with their optimized energy characteristics and increased transmission ranges for localization and emergency calls in case of a fall. Therefore, we present a hardware design of an energy efficient mobile device, the so-called EMU, that includes Sub 1GHz and Wi-Fi transceivers. An optimization of the Wi-Fi localization increased the uptime from 7 h to 9:25 hours. Further, the utilization of Sub 1GHz for localization has more than doubled the uptime to 21 hours, as shown in two benchmarks (measuring perchip power-consumption and system uptime while performing network communication), while achieving a comparable location accuracy.

On the comparability of indoor localization systems' accuracy

While indoor localization is gaining increased relevance, the comparability of the published accuracies for localization algorithms is rarely given since the metrics, node densities and the evaluation environments vary. To overcome this limitation, a simulator for indoor localization algorithms called simLoc is presented which uses prerecorded received signal strengths of two different buildings. simLoc simulates both, different path loss models and different localization algorithms. Therefore, the simulator can be used to compare different algorithms, but it can also be used to find optimal parameter settings. This was done to optimize a localization system for mobile devices equipped with a 868 MHz radio. As a result, the optimized algorithm achieves significantly lower error-distances, floor-errors, and localization-errors than the model-based RADAR system.

MANETSip - A Dependable SIP Overlay Network for MANET Including Presentity Service

This work presents a dependable SIP overlay network for the usage in mobile ad hoc wireless networks focusing the availability of registrar and location services in combination with a reduced message transmission overhead regarding amount and size. In addition we enable a SIP presentity service which offers subscriber presentity state information to others. We show the performance of our approach through measurements with a prototype in a testbed.

Technology Supported Geriatric Assessment

Healthy aging is a core societal aim especially regarding the demographic change. But with aging, functional decline can occur and this is a major challenge for health care systems. For the evaluation of the health of older adults and the identification of early changes associated with functional and cognitive decline, clinical geriatric assessments are a well-established approach. Ideally, the assessments should take place at home of the older adults or even in their daily life, to get an unbiased functional status. Therefore, we introduce a technology supported geriatric assessment as an intermediate step to a home-assessment or in future to sensor-based-assessments in daily life. Beside various ambient sensors, a sensor belt is used during the assessments and for 1 week in the participants’ daily life. We discuss the suitability of our measuring devices for an ambient home-assessment and evaluate the sensors in comparison to valid measurements. Thereby, we show that light barrier measurements achieve a high sensitivity and a good correlation to manual measurements through study nurses or physical therapists.

Threshold-based Fall Detection on Smart Phones

This paper evaluates threshold-based fall detection algorithms which use data from acceleration sensors that are part of the current smart phone technology. The evaluation was done with sampled fall records where young people simulate falls. To test the false positive rate of the algorithms, another record set with Activities of the Daily Living (ADLs) from elderlies was used. The results are very promising and show that smart phone sensors are suitable for fall detection. This will offer a new opportunity to assist elderlies in their daily living and extend their period of self-determined living.

Stair Climb Power Measurements via Inertial Measurement Units - Towards an Unsupervised Assessment of Strength in Domestic Environments.

In order to initiate interventions at an early stage of functional decline and thus, to extend independent living, the early detection of changes in functional ability is important. The Stair Climb Power Test (SCPT) is a standard test in geriatric assessments for strength as one of the essential components of functional ability. This test is also well suited for regular and frequent power measurements in daily life since the activity of climbing stairs is usually frequently performed. We introduce an automated assessment of the SCPT based on inertial measurement units (IMU) in a study of 83 participants aged 70-87 years. For power evaluations of the lower extremities, the activity of climbing stairs was automatically classified via machine learning and the power was calculated based on the test duration and covered height. Climbing stairs was correctly classified in 93% of the cases. We also achieved a good correlation of the power calculations with the conventional stop watch measurements with a mean deviation of 2.35%. The system’s sensitivity to detect the transition towards frailty has been confirmed. Furthermore, we discussed the general suitability of the automated stair climb power algorithm in unsupervised, standardized

Validation of the ambient TUG chair with light barriers and force sensors in a clinical trial

ABSTRACT To initiate appropriate interventions and avoid physical decline, comprehensive measurements are needed to detect functional changes in elderly people at the earliest possible stage. The established Timed Up&Go (TUG) test takes little time and, due to its standardized and easy procedure, can be conducted by elderly people in their own homes without clinical guidance. Therefore, cheap light barriers (LBs) and force sensors (FSs) are well suited ambient sensors that could easily be attached to existing (arm)chairs to measure and report TUG times in order to identify functional decline. We validated the sensitivity of these sensors in a clinical trial with 100 elderlies aged 58–92 years with a mean of 74 (±6.78) years by comparing the sensor-based results with standard TUG measurements using a stopwatch. We further evaluated the accuracy enhancement when calibrating the algorithm via a mixed linear model. With calibration, the LBs achieved a root mean square error (RMSE) of 0.83 s, compared to 1.90 s without, and the FSs achieved 0.90 s compared to 2.12 s without. The suitability of measuring accurate TUG times with each of the ambient sensors and of measuring TUG regularly in the homes of elderly people could be confirmed.

Understanding Jump Landing as an Oscillating System: A Model-based Approach of Balance and Strength Analyses.

Counter movement jumps (CMJ) are well-suited to measure the muscle power and balance. Since it has been clarified that well accepted CMJ amplification-based balance measures (such as TTS or CoP) are significantly influenced by algorithmic, and measurement settings and thus, measurement results have limited meaningfulness among force platforms, we introduce a new model-based approach measuring the postural stability. In this, during the landing and recovery phases after vertical jumps, the lower extremities can be represented by an oscillating system and the corresponding transfer function is described by a second-order delay (PT2)