Citation: Pascher, M.; Kronhardt, K.;
Franzen, T.; Gruenefeld, U.;
Schneegass, S.; Gerken, J. My
Caregiver the Cobot: Comparing
Visualization Techniques to
Effectively Communicate Cobot
Perception to People with Physical
Impairments. Sensors 2022, 22, 755.
https://doi.org/10.3390/s22030755
Academic Editors: Abolfazl Zaraki
and Hamed Rahimi Nohooji
Received: 30 December 2021
Accepted: 15 January 2022
Published: 19 January 2022
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Article
My Caregiver the Cobot: Comparing Visualization Techniques
to Effectively Communicate Cobot Perception to People with
Physical Impairments
Max Pascher
1,2,
* , Kirill Kronhardt
1
, Til Franzen
1
, Uwe Gruenefeld
2
, Stefan Schneegass
2
and Jens Gerken
1
1
Human-Computer Interaction Group, Department of Media Informatics and Communication,
Westphalian University of Applied Sciences, 45897 Gelsenkirchen, Germany;
kirill.kronhardt@studmail.w-hs.de (K.K.); til.franzen@studmail.w-hs.de (T.F.); jens.gerken@w-hs.de (J.G.)
2
Human-Computer Interaction Group, Paluno—The Ruhr Institute for Software Technology,
Faculty of Business Administration and Economics, University of Duisburg-Essen, 45127 Essen, Germany;
uwe.gruenefeld@uni-due.de (U.G.); stefan.schneegass@uni-due.de (S.S.)
* Correspondence: max.pascher@w-hs.de
Abstract:
Nowadays, robots are found in a growing number of areas where they collaborate
closely with humans. Enabled by lightweight materials and safety sensors, these cobots are gaining
increasing popularity in domestic care, where they support people with physical impairments in
their everyday lives. However, when cobots perform actions autonomously, it remains challenging
for human collaborators to understand and predict their behavior, which is crucial for achieving
trust and user acceptance. One significant aspect of predicting cobot behavior is understanding their
perception and comprehending how they “see” the world. To tackle this challenge, we compared
three different visualization techniques for Spatial Augmented Reality. All of these communicate
cobot perception by visually indicating which objects in the cobot’s surrounding have been identified
by their sensors. We compared the well-established visualizations Wedge and Halo against our
proposed visualization Line in a remote user experiment with participants suffering from physical
impairments. In a second remote experiment, we validated these findings with a broader non-specific
user base. Our findings show that Line, a lower complexity visualization, results in significantly faster
reaction times compared to Halo, and lower task load compared to both Wedge and Halo. Overall,
users prefer Line as a more straightforward visualization. In Spatial Augmented Reality, with its
known disadvantage of limited projection area size, established off-screen visualizations are not
effective in communicating cobot perception and Line presents an easy-to-understand alternative.
Keywords: cobot; human–robot collaboration; visualization techniques; projection; virtual reality
1. Introduction
While robots were previously taught to perform simple repetitive tasks, they have
started to evolve into collaborators in our professional and personal lives [
1
,
2
]. As a result,
these so-called cobots support humans in various ways that were unimaginable just a
few years ago. One area that has seen drastic advances in human–robot collaboration is
domestic care, with cobots supporting people with physical impairments [
3
]. These assist
people in various ways [
4
], from activities of daily living (ADLs), including basic tasks such
as drinking, eating, and grooming, to leisure-time activities [
5
,
6
]. In domestic care, cobots
reduce the need for the constant presence of caregivers, empowering people previously
reliant on others for help to regain their independence. Our previous research on the needs
of people with physical impairments showed a strong desire for privacy and alone time,
which can undoubtedly be achieved with reliable robotic support [7].
However, new challenges arise when cobots are tasked with autonomous or semi-
autonomous actions, resulting in additional stress for end-users [
8
]. Close proximity
Sensors 2022, 22, 755. https://doi.org/10.3390/s22030755 https://www.mdpi.com/journal/sensors
