crease the amount of noise in the training as well as
application data and may therefore impair the detec-
tion accuracy.
A further problem exists, if the amount of training
data is small. It might not be possible to acquire a
large amount of training examples in complex appli-
cation scenarios. This is a general problem, since the
detection accuracy of data-dependent signal process-
ing and classification methods depends on the amount
of available training data. Hence, approaches that can
handle a reduced amount of training examples must
be developed and applied.
One approach is to transfer a classifier between
classes, i.e., to perform a classifier transfer (Pan and
Yang, 2010). It could be shown that classifier transfer
for the detection of patterns in the EEG performs well
for a transfer of classifier between tasks in which the
same event related activity has to be detected (Itur-
rate et al., 2013) or between similar types of event
related potentials (ERPs) like different types of error
potentials (Kim and Kirchner, 2013). In a recent work
we showed that the transfer of classifier is also pos-
sible between classes that ”miss” a pronounced pat-
tern, i.e., the P300 (Kirchner et al., 2013). Hence,
the data processing methods (classifiers and spatial
filters) need not to be trained and tested on examples
that are evoked by the same brain processes, like same
or similar error detection processes, but by brain pro-
cesses that evoke brain pattern, which are similar in
shape and characteristics, i.e., miss a prominent ERP
or pattern of ERPs.
By now, our investigations have been conducted
in controlled experimental setups in an offline fash-
ion. In this paper, we investigate the ability to detect
the P300 ERP in a demanding dual task application
scenario that combines an oddball paradigm with a
second task. We show that the detection of P300 re-
lated target recognition processes and even more im-
portant the missing of target recognition processes can
be performed online while a subject is performing a
demanding and realistic interaction task that occupies
the operators attention. This task consists of the tele-
operation of a real robotic arm through a labyrinth via
a virtual immersion scenario.
The paper makes the following contributions: 1)
we demonstrate that the online, single trial detection
of the P300 potential is possible in an application
scenario that is affected by a high number of noise
sources and artifacts and requires dual task perfor-
mance from the subject (Kirchner and Kim, 2012),
i.e., distracts the subject from the perception of task
relevant stimuli; 2) we show that the few number of
examples of training data of a specific class can be
compensated to a certain degree by classifier transfer.
2 APPLICATION SCENARIO
In the proposed application scenario, we investigate
whether it is possible to reliably detect target recogni-
tion processes as well as the missing of target recog-
nition processes while a subject is performing a de-
manding teleoperation task.
Precisely, the experimental setup was as follows
(see Fig. 1): The subjects were wearing an exoskele-
ton that covered their back and right arm (Folgheraiter
et al., 2012), and a smart glove on their hand that were
used as input devices for the teleoperation task.
In addition, participants were equipped with a
head mounted display (HMD) on which the teleopera-
tion site (including surroundings, labyrinth and robot)
could be seen in 3D. Additionally to the 3D environ-
ment, information from the control system, a camera
picture of the real scene and tools like a gyroscope de-
picting the orientation of the end-effector were at any
time in the operators field of view. Head and hand
movements of the operator were tracked (InterSense,
Billerica, USA) and used to update the HMD.
The subjects had two main tasks that had to be
performed at the same time: a) to control a robotic
arm (teleoperation task) using the exoskeleton, and
b) to respond to specific messages (oddball task).
2.1 The Teleoperation Task
In the teleoperation task, the end-effector of a robotic
arm had to be steered through a labyrinth (see
Fig. 1 C). This task is similar to a wire loop game,
i.e., a certain path has to be followed and touching
the labyrinth had to be avoided. The movements of
the robotic arm were controlled via the exoskeleton
by mapping the state and relative position of the ex-
oskeleton components to a Mitubishi PA-10 robotic
arm (see Fig. 1 A in the lower right corner) via a vir-
tual model (see Fig. 1 A in the upper right corner)
thereof (depending on the concrete type of investiga-
tion, see Sec. 3).
The teleoperation task is difficult and demanding
for the subject, and therefore forces the subject to con-
centrate on it. Further, the subject was requested to
rest from time to time. In each run 24± 8 rest periods
had to be performed (Seeland et al., 2013). During
rest the active exoskeleton kept the operators arm in
position. While this was the case the operator was not
allowed to respond to any warning (infrequent task
relevant stimuli, see below) that were presented to
him in an oddball fashion throughout the run.
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