A Full-Body Wireless Wearable UWB-Based Human Motion Capture and Gait Analysis System - E-Healthcare Systems and Wireless Communications - page 437

INTRODUCTION as a promising candidate for real-time human

locomotion tracking with specific application to
clinical gait analysis. In this chapter, we introduce
and investigate a full-body wireless wearable
human locomotion tracking and gait analysis
system using UWB radios that is capable of pro-
viding high ranging and localization accuracies.
In particular, we design the primary components
of the proposed system with specific application
to clinical gait analysis.
The key design challenges that will be ad-
dressed in this chapter are organized as follows.
Initially, the target ranging accuracy, required
signal-to-noise-ratio (SNR), and target sampling
rate will be specified. Based on these requirements,
the calculation of the achievable SNR is necessary
for determining the feasibility of the system under
investigation. Then, the possible receiver struc-
tures will be exploited. Furthermore, the choice
of the appropriate receiver structure as well as the
selection of the corresponding design parameters
that enable for the achievement of the target rang-
ing accuracy will be presented. Moreover, the
arrangement of transceivers (nodes), number of
nodes and their locations are important factors that
will studied, since these factors directly affect the
motion capture data. Then, the determination of
the relative positions of nodes during movement
based on the acquired ranging data and dynamics
of human movement is a challenging task that will
be tackled, where all-nodes are mobile. Finally,
sensor-fusion, system performance, and battery
lifetime will be studied.
The organization of this chapter is as follows.
First, we give a brief background on gait analysis
and highlight the advantage of the application of
UWB to healthcare applications including the
available receiver structures, power consump-
tion requirements of wireless body area networks
(WBANs), and time-of -arrival (TOA) lower
bounds. Then, we give an overview of our pro-
posed system followed by the link budget design
parameters. The ranging stage is then presented
with the corresponding receiver structure and

Observational gait analysis, the standard method of
evaluating gait, refers to the visual assessment of a
patient's gait. Gait analysis by observer assessment
does not use any specialized equipment, and is
simply used to observe abnormalities in gait. Clini-
cal gait analysis, also termed as quantitative gait
analysis, provides a detailed clinical introduction
to understanding and treating walking disorders
(Gross, Fetto et al. 2002; Menz, Latt et al. 2004).
The identification of gait disorders is commonly
assessed by the measurement of the spatial and
temporal parameters of gait 1 . However, it is worth
noting that the techniques and technologies that
work well for measuring normal gait often fail
when applied to abnormal gait (Kiss, Kocsis et
al. 2004; Cappozzo, Della Croce et al. 2005).
Moreover, the criteria valid for clinical research
are not necessarily the same as those valid for
clinical testing (MacWilliams and and D'Astous
2002; Menz, Latt et al. 2004). Accurate measuring
systems, optical tracking systems, are available,
but they require that the test subject move inside a
dedicated laboratory with multiple charge-coupled
device (CCD) cameras and complex settings
(Gross, Fetto et al. 2002; Di Renzo, Buehrer et al.
2007). Subtle abnormalities are not evident when
examined indoors, as when walking is performed
in a laboratory with the patients concentrating on
what they are doing, since this does not necessarily
represent their normal walking (Gross, Fetto et
al. 2002). On the other hand, body-fixed-sensors
do not require such complex settings or highly
skilled operators. Yet, these systems also have
their limitations. A possible solution for overcom-
ing these limitations is to use multiple sensors,
or what is known as sensor-fusion (Cappozzo,
Della Croce et al. 2005; Corrales, Candelas et al.
2008). However, the overall power consumption
and system cost remain as two limiting factors,
where sensory systems are commonly expensive.
The work of this chapter is motivated by the
properties of ultra wideband (UWB) technology