Hi! My name is Andrii Matviienko and I'm from Technical University of Darmstadt, Germany.
On behalf of my co-authors I'm going to present to you our work titled "Reducing Virtual Reality
Sickness for Cyclists in VR Bicycle Simulators". Bicycle simulators are increasingly useful in many
application areas, such as health entertainment and research. As you can see on the slide
most of these bicycle simulators are placed on stationary platforms and employ virtual reality
technology to present a virtual world to users through immersive 3D experience and resulting
high sense of presence. However, due to a mismatch between visual feedback provided by simulation
and physical movement in space while cycling users often experience virtual reality sickness
which leads to the decreased cycling performance and even dropouts from experiments.
Although we cannot avoid mismatch between visual perception and physical movement in VR simulators,
we can influence factors that can reduce VR sickness. These factors include: (1) hardware,
which determines the quality of VR, (2) VR content responsible for degree of VR fidelity
and sickness, and finally (3) human factors, such as age, gender and prior VR experience. We explore
the aspects related to human perception from the second category related to VR fidelity and
sickness. In case of VR simulators these factors are typically influenced by: (1)
rotational movement, e.g., steering that increases mismatch between the visual and vestibular system
and (2) the effect of optical flow when moving through space along different axis.
In the first experiment, we investigated three bicycle steering
methods and in the second one, we explored an air flow and dynamic restriction of view
to reduce the VR sickness under three types of movement through space: (1) cycling on a straight
line, (2) with turns, (3) and with slopes. In the first study, we evaluated three steering methods
based on the head mounted display, handlebar, and upper body. The HMD method allows steering by
turning one's head left and right. The handlebar -- by turning the handlebar, and upper body by
leaning left and right. Therefore, for this experiment we had the following research question:
Which steering method is the most suitable for VR bicycle simulators in terms of VR sickness and
cycling performance? While the handlebar is the conventional method for many bicycle simulators
and leaning of the upper body is the way to steer a bicycle in the real world, we included a
promising method based on the previous research for steering in cars using the head rotation.
With these methods, we aim not only to explore existing steering methods in bicycle simulators,
but also to access level of control with different parts of body, such as hands for handlebar,
head for HMD, and upper body for leaning. To investigate the accuracy of the steering methods,
we placed coins equidistant from each other along a predefined path and instructed participants to
collect as many coins as possible. Every steering method was randomly assigned to
a cycling route and participants' task was to cycle this route by following arrow indications
presented in the simulation and collect the coins placed on the road along the predefined
trajectory. We conducted the experiment in the developed virtual reality bicycle simulator,
which consisted of the bicycle placed on the fixed platform with lateral suspension. As for
the handle bar steering method, we placed one VR tracker on the front wheel to measure the rotation
angle. The HMD steering method was implemented using the orientation of the Vive headset to
capture the head's yaw rotation. Finally, the upper body steering was enabled by the tilting
of the bicycle platform left and right sides similar to cycling on a bicycle in the real world.
For our study we measured the following dependent variables: first of all virtual reality sickness
using SSQ and FMS scales ,cycling accuracy -- we counted the percentage of coins participants
collected on the road, usability of steering methods using the SUS scale,
task completion time, number of collisions they experienced with the virtual objects,
and subjective pleasantness and accuracy. We found that handlebar steering methods
leads to the lowest VR sickness and the lowest number of collisions. Moreover,
it has the highest usability and steering accuracy compared to HMD and upper body steering methods.
However in terms of task completion time, HMD method outperformed the handlebar. Therefore,
we decided to use the handlebar steering for the follow-up experiment as the method with the lower
VR sickness, higher usability and control, accuracy, speed, and highest ranking based
on the subjective feedback. As previous work has shown, airflow and vibration are very commonly
used methods to reduce motion sickness. For example, D'Amour et al. have shown that
continuous airflow at a fixed speed placed in front of participants significantly reduced
cyber sickness compared to vibration in the chair. As for the head mounted vibration,
Peng et al. explored this area to reduce VR sickness while working in VR using vibration.
Moreover, while static a field of view restriction (as shown in the middle
introduced by Fernandez and Finer) is efficient to reduce the VR sickness,
we explored the dynamic field restriction, which is applied on demand in situation that might cause
VR sickness. Therefore, in this paper we explore the methods from the previous works,
such as airflow, dynamic field of view restriction, and head mounted vibration
feedback. To reduce VR sickness in bicycle simulators, airflow creates a wind flow sensation,
field of view dynamically restricts the peripheral vision of cyclists by blacking
out the field of view, and vibration conveys a simultaneous sensation on both sides of the head.
As for the type of movement, we considered cycling on a straight line (movement along one axis),
cycling with turns (movement along two axis), and cycling with slopes (movement along three axis).
With this, we aimed to instigate VR sickness related to different types of locomotion and
investigate, which countermeasure is the most suitable. We conducted the experiment in the
developed a virtual reality simulator as in the first experiment. The only difference in the setup
was the stationary platform, which limits tilting left and right movement. As for the measurements,
we measured again virtual reality sickness using SSQ, FMS, and MSSQ scales. We measured cycling
performance, perceived presence, simulation realism using Likert scale. We found that airflow
is the most efficient method to reduce VR sickness based on the subjective feedback and found that
cycling along the higher number of axis and leads to the higher VR sickness. We also discovered
that three investigated countermeasures become comparably efficient for reducing VR sickness. In
general, VR sickness in bicycle simulators can be addressed by design and external countermeasures.
By adjustments through design we refer to essential components of bicycle simulator,
such as steering, turning cycling platforms, and pedaling, and by external measures we name
non-essential additional components, for example, airflow, on-head vibration, reference frames.
So, to summarize our work, in this paper we investigated methods to reduce VR sickness
in bicycle simulators. We conducted two control experiments focused on the steering and movement
through space. We found that handlebar steering method leads to the lowest VR sickness and has
the highest usability. Moreover, we have shown that VR thickness depends on the type
of movement in VR simulation and increases when VR landscape provides turns and slopes.
Lastly, airflow suggests to be the most promising methods to reduce VR sickness for all three types
of trajectories. With this I would like to end my talk and thank you for your attention.