III. SYSTEM DESCRIPTION
A typical Systems Design approach considers the known
system the system-as-is, that is, the legacy system from
where we take knowledge to carry out the design. As
represented by Fig.2, the proposed device - the modular
exoskeleton Mod-Exo on the right side of the figure - is
treated as the system-to-be. We consider the EXO-C [21]
prototype as the legacy system.
In [6]], a mechanical structure of an exoskeleton, including
motor and reduction, was built. This prototype can be divided
into modules and it’s refered here as Mod-Exo. Modularity
is a property that can also be applied to both software
and hardware and KAOS is expected to help this integrated
design.
The Mod-Exo actuation is provided by a Maxon Motor
EC90, 90 Watt with a 100:1 harmonic reduction and by the
EPOS2 24/5 driver. The interaction force between the arm
and the exoskeleton is obtained by measuring the deflection
of a serial torsion spring. The deflection is provided by the
Fig. 2. The underlying idea of applying Goal Oriented Requirement
Engineering (GORE), a software design tool borrowed from software
engineering, for the integrated hardware and software design of a modular
exoskeleton.
arm position, measured by an absolute encoder and the motor
displacement, measured by the maxon encoder.