Drone rider: Enhanced feelings of flying using a vibratory andpassively inclining foot plate
Kazuya Shimatoh1 , Yuta Goto1 and Shogo Okamoto1
Abstract— This study investigated the effects of two techniques to improve the sense of immersion and flying for flight
simulators in immersive virtual reality environments. To test
their effects, we used a drone simulator, with an operator
standing on a drone and controlling it over a natural landscapeby inclining his/her body toward the travelling direction. The
first technique involved vibratory feedback through a foot platethat delivered the simulated vibration and sounds of the left andright propellers of the drone. The second technique involved
the passive roll and pitch rotation of the foot plate when
the operator actively shifted the center of his/her body mass.
In a user experiment involving 12 participants, the passive
inclination of the stage was found to enhance immersive feelings,
while the vibratory feedback to the soles were found to enhanceboth feelings of flying and immersion. This study helps develop
a drone and other flying simulators using immersive virtualreality settings.

I. I NTRODUCTION
Body levitation in immersive virtual reality (VR) environments allows us to enjoy extraordinary experiences. Further,e-sports requiring moderate exercises could help maintainfitness. We have been developing Drone Rider, which is a
VR experience where a human rides on a drone and flies
over spectacular landscapes or races with other riders throughcity buildings. A key technique for such VR applications isdetermining how to effectively induce a sense of levitationby using haptic or non-visual stimuli.
Earlier studies demonstrated that the combination of vection and haptic stimuli effectively induced the sense of selfmotion [1], [2], [3]. For example, in a study by Nilsson etal. [2], vibratory stimuli to soles were found to influence
the feelings of horizontal travel in a VR setting. Soundstimuli can be also effective in enhancing the sense of selfmotion [4]. Based on these studies, we hypothesize that
audible vibrations to soles along with flight images improve
the sense of levitation and immersion in the drone simulator.
As far as we know, thus far, the effects of vibrotactile
stimulation to the soles on the sense of flying have notbeen investigated for flight simulators in VR environments.
Further, the introduction of passive rotation of the foot plate
would be efficient because it matches the postures of the virtual fuselage and operator. This study experimentally tested
the effects of sole vibration and passive stage inclination on
the sense of levitation and immersion.
1 The authors are with Department of computer science, Tokyo
Metropolitan University, Tokyo, Japan. {shimatou-kazuya,goto-yuta}@ed.tmu.ac.jp, okamotos@tmu.ac.jp

Fig. 1. Experimental setting of VR drone rider. The user wears a virtualreality head set on a vibrotactile foot plate that passively rotates around rolland pitch axes.

II. M ETHODS
A. Apparatus
The apparatus mainly comprised a VR head set (MetaQuest 2, Meta Platforms, Inc., CA), trampoline (Honei,China), and vibrotactile foot plate, as shown in Fig. 1. The
footplate was laid on the trampoline and had two voice-coilmotors (Vp7, Acouve Laboratory Inc., Japan) installed on
its surface for left and right feet. Each motor was placedat the forepart of each foot. They were connected to an
audio amplifier (FX-AUDIO-FX-2020A+, North Flat Japan,Japan). An operator, that is, the rider, stands on the footplate with each foot on the respective voice-coil motor while
holding a safety handle. According to the voluntary shift ofthe center of body mass, the foot plate passively inclines
toward the roll and pitch directions. This design allowed us
to match the body posture and that of a drone in the virtualenvironment, with the aim of improving the feelings of flyingand immersion.
B. Software system and VR field
Unity (2021.3.21f1) was used to develop the drone simulator. The tilt of the VR head set was converted linearly
to the drone’s velocity. The forward/backward speed of thedrone was determined by the pitch angle of the head set.
In addition, the tilt around the roll determined the drone’s
yawing velocity. In the VR environment, the operator flew
over a natural field on a drone. The drone did not movevertically to change its altitude; it moved only over a
horizontal plane without obstacles.

C. Vibratory stimuli to soles
The sound was reproduced by a voice coil motor in contact
with the operator’s soles so that the drone’s propeller soundcould be picked up via the sole as vibrations. When the drone
turned to the left, the rotation speed of the right side propeller
increased, and when it turned to the right, the rotation speedof the left side propeller increased. The vibration amplitudeof the voice coil motor on the opposite side of the turning
direction was increased to represent the increase in volume ofpropeller sound with increasing rotation speed. The voltage
inputs to the voice coil motors were linearly changed withthe angular velocity of the drone.
D. Participants
Twelve university students (four females) in their 20s participated in the experiment after providing written informed
consent. They could freely abandon the experiment if they
suffered from severe motion sickness. The protocol of thestudy was approved by Institutional Review Board, Hino
Campus, Tokyo Metropolitan University (H23-9).
E. Procedures
Before the main experiment, the participant acclimatedto the manipulation of the drone simulator. This session
typically lasted 1–2 min. After the 3-min break, the main
experiment began.
In the main experiment, the participant operated the drone
freely for each of the four conditions (with/without vibration
× with/without passive stage rotation) that were presented in
randomized order. The participant was encouraged to steer
the drone around yaw axis unless motion sickness was felt.
The flight experience lasted 40 s for each condition. In thecondition without passive stage inclination, participants stoodon a wooden board placed on a trampoline frame. In the novibration condition, the experiment was conducted by having
participants stand on a foot plate without a voice coil motor.
The vibratory foot plate was used merely to produce thepropeller sounds.
After the experience, participants immediately answeredeach of the following questions using a 9-point scale (1:little and 9: very much). Questionnaire items were Q1 (Didyou feel like you were flying?) and Q2 (Was the experience
immersive?). After completing the questionnaire, participants
rested on a chair for 3 min before the next trial.
F. Data analysis
For each question item, the reported scores were standardized (z-score) for each participant. The standardized scoresof Q1 (sense of flying) and Q2 (sense of immersion) werethen analyzed using the two-way analysis of variance withthe trampoline and vibratory stimuli conditions being twofactors.
III. R ESULTS
Tables I and II summarize the results of the analysis ofvariance for Q1 and Q2, respectively. As depicted in Table I,
the vibration to soles was effective for the sense of flying;

TABLE IS UMMARY TABLE OF ANALYSIS OF VARIANCE FOR Q1 (S ENSE OFFLYING )FactorPassive inclination
Sole vibration
Interaction
Error
Total

Sum of squares
0.31
4.35
0.16
22.19
27.0d.f.
1114447

F -value
0.61
8.62
0.32

p-value
0.440.0053
0.57

TABLE II
S UMMARY TABLE OF ANALYSIS OF VARIANCE FOR Q2 (S ENSE OFIMMERSION )FactorPassive inclination
Sole vibration
Interaction
Error
Total

Sum of squares
2.95
3.56
0.11
29.38
36

d.f.
1114447

F -value
4.42
5.33
0.16

p-value
0.041
0.026
0.69

however, the passive rotation of the stage was not. Further,as depicted in Table II, both the vibration and passive stage
were effective for the sense of immersion.
IV. D ISCUSSION AND C ONCLUSION
We evaluated the effects of passive inclination of the footplate and vibratory stimuli to soles, representing propellers,on the sense of flying and immersion in a VR setting where ahuman rides on a drone and enjoys flying over a natural park.
A user study revealed that sole vibrations increased subjective scores for feelings of flying and immersion. Further, thepassive foot plate motion led to an increase in the immersion
score. A few participants reported moderate levels of motion
sickness, which should be alleviated in the future.
Contrary to our expectations, passive rotation of the stage
on the trampoline did not improve operators’ feeling oflevitation. This may be because the inclination of the drone’s
CG imperfectly matched that of the operator’s body in oursetup. The posture of the drone was determined by that of thehead set and, thus, did not directly refer to the inclination of
the foot stage. This issue will be resolved in the future andwe will further explore the effect of passive stage rotation.
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