Comparison of 3D scanned human models for off-body communications using motion capture

Body area networks are complex to analyze as there are several channel mechanisms occurring simultaneously, i.e. environmental multipath together with body motion and close coupling between worn antennas and human tissue. Electromagnetic (EM) simulation is an important tool since not all studies can be done on a real human. In order to gain insight into off-body communication involving a worn antenna, this paper uses a 3D animated model obtained from a 3D surface scanner and a motion capture system for full wave simulation of channels at 2.45 and 5.5GHz. To evaluate if the model can represent body area radio channels in general, a comparison of S21 of the simulated model with measurements from 5 other models of similar height to the main test subject is presented

Conformal switched beam antenna

A cylindrical switched beam antenna making use of Kapton film and aperture-coupling is presented. The use of four elements controlled via a high frequency switching stage is proposed. Using very simple bias circuitry, switching can be achieved to provide four-way coverage at 0°, 90°, 180° and 270°. Elements consist of an aperture-coupled patch making use of thin film technology to provide an air substrate for increased efficiency and therefore gain. Four direction beam switching is performed using only three switches integrated into the structure. Simulated results of a single element are presented, followed by measured results of the fully fabricated structur

Investigation of a Switchable Textile Communication System on the Human Body

In this paper, a switchable textile communication system working at 2.45 GHz ISM band is presented and studied for different locations within a realistic on-body environment. A 3D laser scanner is used to generate a numerical phantom of the measured subject to improve the accuracy of the simulations which are carried out for different body postures. For the off-body communications, the system is acting as an aperture coupled microstrip patch antenna with a boresight gain of 1.48 dBi. On-body communication is achieved by using a textile stripline, which gives approximately 5 dB transmission loss over 600 mm distance. The system is switched between on and off-body modes by PIN diodes. Common issues, such as shape distortion and body detuning effects which the textile antenna may experience in realistic use are fully discussed. Robust antenna performance is noted in the on-body tests, and an additional 3 dB transmission coefficient deduction was noticed in the most severe shape distortion case

Impulse Radio-Ultra Wideband Communications for Localisation and Tracking of Human Body and Limbs Movement for Healthcare Applications

Accurate and precise motion tracking of limbs and human subjects has technological importance in various healthcare applications. The use of Impulse Radio Ultra Wideband (UWB) technology due its inherent properties is of recent interest for high accuracy localisation. This paper presents experimental investigations and analysis of indoor human body localisation and tracking of limb movements in 3D based on IR-UWB technology using compact and cost-effective body worn antennas. The body–centric wireless channel characterisation has been analysed in detail using parameters such as path loss magnitude, number of multipath components, RMS delay spread, signal amplitude and Kurtosis with the main focus to differentiate between line-of-sight (LOS) and non-line-of-sight (NLOS) situations. Fidelity of the received signal is also calculated for different activities and antenna positions to study the pulse preserving nature of the UWB antenna when it is placed on the human body. The results reported in this paper have high localisation accuracy with 90 % in the range of 0.5 to 2.5 cm using simple and cost-effective techniques which is comparable to the results obtained by the standard optical motion capture system

UWB Channel Characterization for Compact L-Shape Configurations for Body-Centric Positioning Applications

This paper presents an analysis on the body-centric channel parameters classification for various compact 3 base station L-Shape configurations utilizing only a 2D-plane for installation. Four different L-Shape configurations (x-z/y-z plane) are studied (facing-front/side/back) by varying the position of the base stations in an indoor environment. Results and analyses highlight the variation of the channel parameters with respect to the orientation of the base station configurations and presence of the human subject. Channel parameters values (peak power delay profile (PDP)/rms delay spread sigma/Kurtosis) are reported for (line of sight (LOS): -65 to -50 dB/0.5-5 nsec/40-60) and (non-line of sight (NLOS): -80 to -65 dB/ 10-25 nsec/ 5-25). The 3D localisation accuracy obtained is highest (1-3 cm) for the x-z plane L-Shape configuration facing-front which has maximum number of LOS links (70%).The accuracy decreases by 1-2 cm for the x-z plane L-Shape configuration facing-back due to increase in NLOS links (70%) between the wearable antennas and the base stations

A Study of Factors Affecting Wrist Channel Characteristics for Walking Postures using Motion Capture

The creation of a 3D animated human model (avatar) to be used in Electromagnetic (EM) simulation software is described for low-outage Body Area Network applications such as healthcare. Scanned surface data of a human model is combined with movement data from a Motion Capture system to simulate an on-body channel between two Dual Band Metallic Button Antennas (DBMBAs) mounted on the wrist & chest and the wrist & hip during walking. An investigation of how different factors such as human geometry parameters, arm swing and wrist twisting can affect the body-centric channel during walking action is presented together with the relative significance of each of these factors on predicting body-centric channel gain

Antennas and Propagation for Body-Centric Wireless Communications

Many phantom models with detailed external and internal features have been introduced in recent years by researchers and are now provided with commercial electromagnetic simulators. Phantoms vary in size, resolution, internal structure and posture. Although some phantoms can be posed, it is not straightforward to recreate the exact positions of test subjects for validation purposes. This section focuses on creating a moving human model with postures closely corresponding to those used in measurements to be used for validation in EM software

Body gain study for animated human model in a body worn antenna system

This paper presents the study of body gain in a Body worn antenna system using both measurement and simulation. The simulation has been done in XFdtd, EM (electromagnetic) simulation software, using a 3D-surface scan of a test person. The gesture of the body and positions of antennas on the 3D body surface in the simulation were extracted from data obtained by a motion capture system while the actual measurement was taking place using the dual band metallic button antennas. Additional simulation is done on a standard model available in XFdtd to compare the quality of created 3D model from this research

Localization of Wearable Ultra Wideband Antennas for Motion Capture Applications

This paper presents a study of human body localisation using Ultra Wideband (UWB) technology. Various base station configurations, time of arrival and first peak detection algorithms are used to estimate the position of body-worn antennas. Localisation error as small as 1-2 cm has been achieved using 8 base stations which is comparable to the measurement accuracy obtained by complex optical motion capture system to determine the absolute displacement error. The localisation error obtained is better by a third in comparison to common commercial system based on UWB technology. The results demonstrate that Cuboid-shape configuration with 4 base stations gives slightly low average percentage error (2 to 3%) in comparison to Y-shape (4%). However, the Y-shape configuration is more compact and provides setting up simplicity, which makes it convenient for various applications ranging from healthcare monitoring to entertainment technologies either laboratory based or in-home