Our endeavor represents part of the Robo-Mate project
[18], which aims to deliver a powerful, easy and intuitive
exoskeleton to command. The goal of Robo-Mate is to
develop a wearable powered device to substantially reduce
spinal loads during lifting activities.
This paper is structured as follows: Section II describes
the properties of common thin film force sensors and their
applications in exoskeleton-foot sensors. This section also,
introduces our developed simulator environment in which
virtual force sensors can be designed from its force/resistance
characteristics. The specific contribution of this paper is
presented in Section III, the design of the Exoshoes which
describes the concept and hardware prototype to be integrated
in the exoskeleton. Section IV describes the developed
simulation environment and the results from the simulation
with a virtual human operator wearing the exoskeleton and
exoshoes when walking and lifting/lowering a heavy weight.
Section V presents the experimental setting and experimental
results. Conclusions are proposed in Section VI, which also
points at some of the next steps and future challenges
expected in the future work.
Fig. 1: Virtual force sensor curves.
II. FORCE SENSORS
Initial attempts to have foot-force sensors to measure the
pressure applied in the front and rear parts of the foot (ball
and heel of foot) are described in [3]. Their proposed floor
reaction force (FRP) sensor detects air pressure changes
sensed when foot-pressure is applied to their customized
air-pressure force sensors. Up to today the electrical force
sensors instead of air pressure based sensors are widely
applied. For instance, thin film sensors such as flexiforce
(Tekscan
R ) or shunt force sensor (Sensitronics
R ) are ideal
for integration in footwear, as they have small thickness
of less than one millimeter to fit into the limited space
of the footwear. In addition, these types of force sensors
are an inexpensive and lightweight alternative to multi-axis
force/torque sensors.