Tripping and slipping are serious health concerns
for the elderly because they result in life threatening injuries i.e.,
fractures and high medical costs. Our recent work in detection
of tripping gait patterns has demonstrated that minimum
toe clearance (MTC) is a sensitive falls risk predictor. MTC
measurement has previously been done in gait laboratories
and on treadmills which potentially imposes controlled walking
conditions. In this paper, we describe a prototype design
of a wireless device for monitoring vertical toe clearance.
The sensors consists of a tri-axis accelerometer and dual-axis
gyroscope connected to Crossbow sensor motes for wireless
data transmission. Sensor data are transmitted to a laptop and
displayed on a Matlab graphic user interface (GUI). We have
performed zero base and treadmill experiments to investigate
sensor performance to environmental variations and compared
the calculated toe clearance against measurements made by
an Optotrak motion system. It was found that device outputs
were approximately independent of small ambient temperature
variations, had a reliable range of 20m indoors and 50m
outdoors and a maximum transmission rate of 20 packets/s.
Toe clearance measurements were found to follow the Optotrak
measurement trend but could be improved further by dealing
with double integration errors and improving data transmission
rates.