Aim: Because of the increasing complexity of
industrial work processes, the use of so-called
virtual reality technical support is becoming
more common. Mobile augmented reality
(MAR) offers work assistance solutions for
complex manual production processes in a
variety of fields of application. In such processes,
appropriate information is projected
into the user’s field of vision, e.g. via headmounted
displays (HMD). The aim of the
present study was to estimate the strain reaction
of workers using two different HMDs:
Nomad and LitEye. The results were to indicate
whether one of the tested HMDs was to
be preferred for industrial processes.
Methods: 10 male volunteers (age 27.7 ± 3.2
years) were enrolled for this study. The psycho-
physiological strain of two hours work
in a reference workplace fulfilling selection
tasks with the two HMDs (Nomad vs. LitEye)
and the usual method with a paper list (PL)
was estimated. For strain evaluation, the
mental state scale of Zerssen & Koeller (1976),
the profile of mood state (or Eigenzustandskala)
of Nitsch (1976) and a complaints questionnaire
were applied for all participants before
and after work. The heart rate variability
(HRV) was recorded during the whole twohour
work phase using a digital long-time
ECG-recorder (Microvit MT-101, Schiller). In
addition, the number of tasks completed
and the number of errors were determined
as parameters of performance.
Results: The comparison of the two HMDs
did not reveal any differences in strain. Nor
did the HRV indices reveal any differences.
The number of tasks completed was significantly
lower with the paper list than with the
HMDs. With the Nomad-HMD, the number of
counting errors was less than with the LitEye-
HMD.
Conclusions: These results show that both
tested HMDs are suitable for continuous twohour
application in selection tasks. The use
of MAR does not result in a higher strain for
the user, independent of the HMD technology.
In order to decide which tested HMD is
more eligible for industrial manufacturing
further long-term investigations are necessary.
