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Cyborg insect also referred as insect-machine hybrid robot, consists of a living insect platform and an electronic backpack mounted on. The small size and magnificent walking ability of the insect make this hybrid system a potential candidate for search and rescue missions. The great locomotory capability helps the insect to cope with the complex and unpredictable terrains, whereas the tiny dimension allows it to easily enter the debris of post-disaster sites. There is a necessity to establish more controllable mobility for cyborg insects to develop more efficient maneuver plans. Here, this study demonstrates the control of sideways and forward walking in a cyborg beetle by emulating the touch responses of mechanoreceptors on the insect’s elytra using the electrical stimulation. The beetle walked sideways leftward when the right elytron was stimulated, and vice versa. The forward control was attained by stimulating both elytra simultaneously. In addition, these elicited motions were found to be graded by tuning the stimulation frequency as increasing the frequency sped up the sideways walking and slowed down the forward velocity. Besides complementing the controllability of the cutting-edge cyborg insects, this graded response is essential for improving the navigation in cyborg insects for search and rescue missions. VIDEO LINK: https://youtu.be/FLNF9_nfOow
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Transactions on Medical Robotics and Bionics
TMRB-04-20-OA-0130 1
Abstract— Cyborg insect also referred as insect-machine hybrid
robot, consists of a living insect platform and an electronic
backpack mounted on. The small size and magnificent walking
ability of the insect make this hybrid system a potential candidate
for search and rescue missions. The great locomotory capability
helps the insect to cope with the complex and unpredictable
terrains, whereas the tiny dimension allows it to easily enter the
debris of post-disaster sites. There is a necessity to establish more
controllable mobility for cyborg insects to develop more efficient
maneuver plans. Here, this study demonstrates the control of
sideways and forward walking in a cyborg beetle by emulating the
touch responses of mechanoreceptors on the insect’s elytra using
the electrical stimulation. The beetle walked sideways leftward
when the right elytron was stimulated, and vice versa. The forward
control was attained by stimulating both elytra simultaneously. In
addition, these elicited motions were found to be graded by tuning
the stimulation frequency as increasing the frequency sped up the
sideways walking and slowed down the forward velocity. Besides
complementing the controllability of the cutting-edge cyborg
insects, this graded response is essential for improving the
navigation in cyborg insects for search and rescue missions.
Index Terms— Cyborg beetle, insect-machine hybrid robot,
Zophobas morio, elytra, electrical stimulation, graded response,
locomotion control, sideways walking
I. I
NTRODUCTION
YBORG insects are hybrid systems fused of living insect
platforms and miniature electronic devices [1-10]. They
are also referred as living robots, insect-machine hybrid robots,
or insect biobots. Such hybrid robots are potential candidates
for search and rescue missions in post-disaster situations owing
to their small size (2-7 cm), light weight (0.5-8 g) and especially
their superior locomotion ability compared to artificial robots
[11-14]. Taking advantage of the miniature dimension, the
living insects are able to traverse across rubble or penetrate into
tiny gaps to seek trapped victims without causing additional
collapses. Furthermore, these small creatures possess a natural
capability to effortlessly perform their locomotion in complex
and dynamic terrains such as the chaotic environment after
calamities. Compared to this simplicity in locomotory
manipulation, synthetic robots require much more complicated
control algorithms as well as sophisticated hardware
*Research supported by Singapore Ministry of Education
H.D. Nguyen is with School of Mechanical & Aerospace Engineering,
Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (e-
mail: nguyenhu005@e.ntu.edu.sg).
P.Z. Tan is with School of Mechanical & Aerospace Engineering, Nanyang
Technological University, 50 Nanyang Avenue, 639798 Singapore (e-mail:
pakzzzan@hotmail.com).
configurations to approximately meet the insect’s maneuverer
ability [11, 15, 35]. Besides, cyborg insects are more
sustainable since they consume less energy and the insects are
fully biodegradable. The main power consumption of cyborg
insects comes from the locomotion control which draws only
few hundreds µW from the electronic devices [8, 16]. On the
contrary, the energy consumed by artificial robots is much
higher due to not only the control system but also the actuators
as well [11, 15, 35]. In addition, the mass production of these
synthetic robots might be costly and less environmentally
friendly.
Locomotion control of the hybrid robots was achieved by
stimulating particular sensory, neural, or muscular organs of the
insects with suitable electrical pulse trains [7, 16-18]. While
neuromuscular stimulation enabled inflight steering, thrust
control [9, 19-21] as well as alternated walking gait [22-24] in
giant beetles (Mecynorrhina Torquata), the method is not yet
practical to fully manipulate the cyborg insect. There is not only
a probability of muscle impairment during implantation but also
a challenge to achieve walking control via a complex wiring for
all the leg muscles [6, 16]. Electrical stimulation of optic lobes
was employed to initiate and cease the giant beetles’ flight [25].
Although there was an attempt to stimulate the insect’s ganglion
for walking manipulation [7], locomotion of terrestrial cyborg
insects was controlled mainly by stimulating the
mechanosensory organs in antennae and cerci to induce turning,
speeding, and backward motions [1, 8, 26]. The ganglion
implantation requires the electrodes to be inserted deeply inside
the insect body which is difficult to precisely target the
stimulation sites without impairing other organs. Antennae and
cerci stimulations are more feasible and cause less damage as
the implantation sites are mostly insulated.
The first terrestrial cyborg insect was introduced by Holzer
et al. in 1997 [1]. The authors applied electrical pulse trains to
the right or left antenna of a living American cockroach
(Periplaneta Americana) to steer it toward the left and right
side, respectively. The animal was then navigated to follow a
straight path. This directional response of the cockroach to the
electrical stimulation of its antennae was found to be consistent
with the evasive response to the tactile stimulation: a sudden
touch to one antenna would result in a rapid turn toward the
H. Sato is with School of Mechanical & Aerospace Engineering, Nanyang
Technological University, 50 Nanyang Avenue, 639798 Singapore (phone:
(+65) 6790 5010; e-mail: hirosato@ntu.edu.sg).
T.T. Vo-Doan is with Institute of Biology I, University of Freiburg,
Hauptstrasse 1, 79104 Freiburg, Germany (phone: (+49) 761 - 203 - 2539; fax:
(+49) 761 - 203 - 2921; e-mail: vodoan@bio.uni-freiburg.de).
Sideways Walking Control of a Cyborg Beetle
Huu Duoc Nguyen, Student Member, IEEE, Pak Zan Tan, Hirotaka Sato, Member, IEEE, and T.
Thang Vo-Doan
C
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Transactions on Medical Robotics and Bionics
TMRB-04-20-OA-0130 2
opposite direction followed by a quick dash to escape [27, 28].
Such stimulation method was then replicated in other species
such as Madagascar hissing cockroaches (Gromphadorhina
Portentosa) [5], Discoid cockroaches (Blaberus discoidalis) [7]
and darkling beetles (Zophobas morio) [8]. The forward
acceleration was achieved by stimulating the cockroach’s cerci
to trigger its escape response [6, 29-31] while the backward
walking was induced by simultaneously stimulating both
antennae of the beetle [8]. In addition, the graded response of
the insect to the stimulation was also demonstrated as an
important input to establish a feedback control system for
navigating the cyborg insects [8].
There have been many remarkable results on the locomotion
control of cyborg insects reported since its first introduction,
especially on the four basic motions such as backward/forward
walking and left/right turning. However, the ultimate goal of
these hybrid systems, which is to operate on a complex, uneven,
dynamic and unpredictable post-disaster terrains, would require
a greater locomotive capability. Thus, there is a necessity to
introduce further controllable mobility that would incorporate
with the established motions to develop efficient maneuver
plans coping with the unpredictability and complexity of the
terrains.
Herein, this study presents the sideways walking control of a
cyborg beetle, which was inspired by the insect’s response to
the activation of its elytra’s mechanoreceptors, as a complement
to the current controllability. This hybrid robot consisted of a
darkling beetle (~0.5 g) Zophobas morio, and a wireless
electronic backpack (~0.45 g) powered by a micro lithium
battery (~0.2 g) (Fig. 1A). The electrical stimulation of left and
right elytron induced the rightward and leftward sideways
walking, respectively. In addition, stimulating both elytra
simultaneously drove the beetle forward. The sideways and
forward walking speed was graded by adjusting the stimulation
frequency. Furthermore, the energy consumption for the
locomotion control was as low as 150 µW per each stimulus.
These new controllable motions, complementing the
mobility of the cutting-edge terrestrial cyborg insects, enable
the establishment of sophisticated maneuver processes to deal
with the complexity of post-disaster terrains. In addition, the
graded response will contribute to the development of a
feedback system for the precise navigation of insect-machine
hybrid robots.
II. E
XPERIMENTAL
P
ROCEDURE
A. Living insect platform
Zophobas morio, also known as darkling beetle, was used as
the insect platform for this study. The relatively small size (~2–
2.5 cm) and light weight (~0.4–0.6 g) made this beetle an ideal
platform for developing the hybrid robot. A colony of this insect
was reared inside the laboratory environment. Temperature and
relative humidity were maintained at ~25°C and 60%,
respectively. Water and food were supplied to the territory
every two weeks.
B. Wireless backpack stimulator
The miniature wireless backpack was fabricated to enable the
electrical stimulation of the cyborg insect (Fig. 1C-D). This
backpack employed an Atmel Tiny 85 (20MHz, 8K RAM)
microcontroller as the main core providing up to two
independently controllable stimulation channels. The wireless
control was actualized with an infrared (IR) receiver (Vishay
TSOP37238) installed on the backpack. The stimulation
command issued by users through a remote control (Fig. 2A)
was wirelessly transmitted to the IR receiver where it was
Fig. 1. (A) Overview of a cyborg beetle. The hybrid robot consisted of a wireless stimulator backpack mounted on a living insect, Zophobas morio. The backpack
was powered by a lithium battery (1.5 V, 1.8 mA). Three electrodes connected with the backpack’s output terminals were implanted into the insect to actualize
the electrical stimulation. (B) X-Ray images of the implants. The common electrode was implanted into the middle region of the pronotum, whereas the two
working electrodes were inserted into each elytron through the vein of their leading edge. (C) Schematic of the backpack. (D) Top view (left) and bottom view
(right) of the stimulator. CE, common electrode; WE, working electrodes; MCU, microcontroller ATtiny85V.
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Transactions on Medical Robotics and Bionics
TMRB-04-20-OA-0130 3
subsequently sent to the microcontroller to execute and
generate corresponding electrical stimulus. The TSOP37238
receiver allowed a wireless transmission distance up to 24
meters line of sight. The backpack was powered by a micro
lithium battery (1.5 V, 8mAh). The fully assembled backpack
was mounted on the pronotum and elytra of the insect using
beeswax or double-sided tape (Fig. 1A).
C. Implantation
Prior to implantation, the insect was anesthetized using CO
2
for immobilization purpose. Three Teflon-coated silver wires
(70 µm diameter, bare; 100 µm diameter, coated; AM Systems)
were used as electrodes. The insulation layer at two ends of each
wire was removed using flame to enable electric conductivity.
One of these ends was then connected to the backpack’s
terminals, whereas the other was implanted into the insect. To
perform the insertion of the electrodes, an insect pin (No. 00,
Indigo Instruments) was used to pierce three tiny holes on the
insect body: one at middle region of the pronotum and two at
the leading edge’s vein of each elytron (Fig. 1B). The common
electrode (GND) was then implanted into the pronotum,
whereas the two working electrodes were inserted into the
elytra. All the implants were retained at ~2 mm depth and
secured with beeswax. The insect was then let to fully recovery
(~1 hour) before the experiment.
D. Electrical stimulation and the 3D motion tracking system
to study locomotion of the untethered insect
Pulse-wave signal was applied to study the insect’s response
to the electrical stimulation of its elytra. The stimulus
parameters were varied by users through an IR remote control
(Fig. 2A). The stimulation command was wirelessly transferred
to the backpack to issue the corresponding stimulus. Amplitude,
pulse width, and duration of the stimulating pulse train were
fixed as 1.5 V, 5 ms, and 1 s, respectively. These parameters
were observed as the threshold to obtain clear responses from
the beetle. The impact of the stimulation on the insect’s
locomotion was investigated with the variation of the
stimulation side and frequency that either individual elytron or
both elytra was stimulated, and the pulse train frequency was
adjusted from 10 Hz to 60 Hz. The sequence of this variation
was randomized to avoid bias and prevent the insect from
adaptation. A period of free walk was allowed prior to each
stimulus and a minimum of 1 s interval was kept between trials.
To record the insect’s trajectory, a three-dimensional (3D)
motion capture system was employed (Fig. 2A). The system
comprised four IR cameras (Bonita VICON®, 1 Megapixel
resolution) operating at 100 frames per second. The position
captured by these cameras was streamed to a computer and
logged for post-experimental analysis. The position of the
insect was synchronized with the stimulation command using a
customized software written in MATLAB®. To enable the four
IR cameras to track and capture the insect’s movement, a light
carbon fiber frame carrying three retroreflective markers (~20
mg, 3M Scotchlite 7610) representing the insect’s location and
orientation, was attached onto the backpack using beeswax
(Fig. 2B).
E. Tactile stimulation and the motion-tracking system to
study locomotion of the tethered insect
An insect treadmill [1, 6, 8] and a tactile stimulator were
assembled to investigate the tactile response of the beetle in the
tethered walking condition (Fig. 3). The system consisted of
four main components: (1) a treadmill structure carrying a
Styrofoam ball, (2) a mini axial fan to create an air cushion that
supported the ball and allowed free motion of the beetle, (3) two
ADNS-9800 laser-optic motion sensors set up perpendicular to
each other to measure the motion of the ball, and (4) one
Arduino Uno board that acquired the sensors’ reading and fed
Fig. 2. Experimental setup for the electrical stimulation of the elytra. (A)
The
experiment was conducted on a Styrofoam sheet (0.6x1.2 m
2
) placed inside
the viewable region of four IR
cameras (Bonita VICON®). The beetle was
wirelessly stimulated using an IR remote control. (B)
A Carbon fiber structure
carrying three reflective markers was mounted on the insect’s back to
represent its body. Cartesian coordinates of the three markers captured by the
IR cameras were transferred to and stored in a computer for post-
experimental
analysis. (C)
The tracked coordinates were displayed on the interface of the
software Vicon Tracker®.
Fig. 3. Overview of the experimental setup for the tactile stimulation. (A) –
(B)
The insect was placed on the top of a Styrofoam ball (radius of 3.5 cm)
using a tiny rod which was joined to its pronotum. Two laser-
optic sensors
were set up perpendicular to each other to read the posit
ional data of the ball.
A commercial Mighty Zap linear actuator equipped with a short needle and a
piezo sensor was employed as the tactile stimulator. The needle was used to
enhance the stimulus, whereas the piezo sensor was applied to distinct between
the stimulated and free walking data. (C)
The relative position between the
insect and the stimulator was manually adjusted to focus the stimulus on the
elytra region (red and green dots indicate right and left elytron, respectively).
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Transactions on Medical Robotics and Bionics
TMRB-04-20-OA-0130 4
them to a computer for further analysis. A customized program
was written in MATLAB® to extract and analyze the insect’s
movement.
To mechanically stimulate the insect’s elytra, a linear
actuator (D12-6PT-3) with a piezoelectric sensor (Minisense
100) mounted at its tip was implemented (Fig. S3). The
actuator’s amplitude and frequency were respectively set to 1
cm and 7 Hz which was the threshold for the insect’s apparent
responses. The stimulation of each elytron consisted of three
periods: the first period lasted 3 s in which the insect was
allowed to walk freely on the ball; the actuator was then
launched in 5 s to create the tactile stimulus; after which 3 s of
another free walking duration was recorded. The positional data
of the Styrofoam ball was sampled at 125 Hz and synchronized
with the touch event owing to the piezoelectric sensor’s
reading. The stimulated side was switched after ten consecutive
trials.
F. Data analysis and statistics
The beetle trajectories were extracted to contain 1 s of data
points during the electrical stimulation and 0.25 s before and
after the stimulus. The data was then smoothed using 0.5-
second moving average prior to the velocity calculation. The
velocities were projected on the beetle longitudinal axis for
forward (or longitudinal) speed and lateral axis for sideways (or
lateral) speed. The heading angle was calculated based on the
positions of the head and tail markers of the marker set attached
on the beetle (Fig. 2B). The induced speed was obtained by
subtracting the speed by the onset value of each trial. While the
amplitude, duration and pulse width of the stimulation pulse
train were fixed, the stimulation frequency was altered
randomly to have the fair effect of each frequency on the
beetle’s response as well as to avoid habituation.
The significance of the induced speed and heading angle was
validated using one sample t-test with significant level of 0.05
for each stimulation condition (Supplementary Table. S1-S5).
The graded response of the insect to the electrical stimulation
frequency was examined using Spearman’s correlation test
(0.05 significant level). The data of 50 Hz and 60 Hz was
excluded from the statistic test due to abnormal behavior of the
beetle in these conditions.
III. R
ESULTS AND
D
ISCUSSION
A. Sideway walking under the tactile stimulation of the
elytra
The tactile stimulation of an elytron induced the beetle to
move contralaterally to the side of contact. The beetle moved to
the left when the right elytron was stimulated, and vice versa
(Fig. 4A, N = 5 beetles, n = 46 trials). In addition, the change in
heading angle of the beetle during the stimulation was
insignificant, which was 7.23 ± 37.59 degrees and 4.10 ± 28.92
degrees for right and left stimulation, respectively (Fig. 4B, t-
test, P > 0.3, df = 22, Supplementary Table. S2). This response
implied that the insect performed a sideways walking motion
under the tactile stimulation. Such reaction might be a form of
an escape or avoidance behavior underlain with the activation
of mechanoreceptors [36-39], which was caused by the
mechanical forces of the stimulus, distributed on the insect’s
elytra.
The beetle increased its sideways (lateral) speed during the
stimulation (Fig. 4C, t-test, P < 0.001, df = 22, Supplementary
Table. S1). The maximum sideways speed in both cases reached
around 10 mm/s after ~2 s from the initiation of the tactile
Fig. 4
. Response of the beetle to the tactile stimulation of its elytra (N = 5
beetles, n = 46 trials). (A)
The trajectories of the beetle induced by the
stimulation. The beetle walked to the contralateral side when an elytron was
touched by the stimulator. The
red and green curves denote the trajectory
induced by the right and left elytron, respectively. (B)
The change of heading
direction of the beetle caused by the stimulus. The beetle generally kept
its
orientation during the stimulation. The black lines and fan-
shaped curves
represent the mean and histogram of the heading angle change, respectively.
(C) – (D)
The insect’s sideways and forward walking speeds. The beetle
increased both sideways and forward velocities during the tactile stimulus.
The black lines denote the none-
stimulation period while the red and green
lines indicate the right and left stimulation duration, respectively. The shaded
regions show the standard deviation of the speed.
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Transactions on Medical Robotics and Bionics
TMRB-04-20-OA-0130 5
stimulus. The induced velocity then gradually dropped down to
~4 mm/s for both elytra. Like several insects, this would be
referred to as a pre-programmed evasive tactic [32, 33]. In this
particular case of the elytra stimulation, the escaping strategy
might be a rapid acceleration followed by a constant run. The
latency of the response would indicate that the beetle needed
around 1 s to notice the thread from the tactile stimulus. Also,
the beetle increased the forward (longitudinal) speed with a
peak of around 10 mm/s when either elytron was stimulated
(Fig. 4D).
This tactile response of the beetle suggested a potential of
achieving sideways walking control via electrical stimulation,
which can activate mechanoreceptors on the elytra. Similar
approaches were already performed to obtain on-demand
steering in cockroaches and beetle where electrical pulses were
transmitted to the insects’ antennae [5, 6, 8, 17]. Such
attainment of sideways walking control would expand the
mobility of the cutting-edge ambulatory cyborg beetles.
B. Sideways and forward walking control using the electrical
stimulation of the elytra
The response of the beetle to the electrical stimulation of its
elytra was in agreement with that caused by the tactile stimulus
(Fig.5, N = 4 beetles, n = 186 trials). The beetle exhibited the
contralateral move when an elytron was stimulated (Fig. 5A).
In addition, there was insignificant change in the insect’s
heading angle caused by the stimulus (t-test, P > 0.05, df > 12,
Supplementary Table. S4). For example, the heading angle
change at 20 Hz was -2.67 ± 15.11 degrees and 4.83 ± 11.27
degrees for the left and right elytron stimulation, respectively
(Fig. 5B, Supplementary Fig. S1-S2, Supplementary Table. S2).
This reaction signified a sideways walking motion elicited by
the electrical stimulation of the insect’s individual elytron
(Supplementary movie). While the beetle kept its heading angle
when the stimulation frequency was in the range of 10 Hz to 40
Hz, it tended to perform ipsilateral turns when the frequency
was above 50 Hz (Supplementary Fig. S1-S2).
The beetle increased the sideways speed towards the walking
direction spontaneously once the stimulus was applied (Fig. 5C
and Supplementary Fig. S3-S4). This tendency was maintained
when the elytron was stimulated at the frequencies from 10 Hz
to 40 Hz (t-test, P < 0.02, df > 12, Supplementary Table. S3).
When the stimulation frequencies were within 50 Hz and 60 Hz,
the beetle only increased the sideways speed in 0.5 s, then
recovered and even moved to toward the ipsilateral side
(Supplementary Fig. S3-S4). The sideways speed was graded
from ~40 mm/s to ~60 mm/s when the stimulation frequency
was tuned from 10 Hz to 40 Hz (Fig. 5D, Spearman’s
correlation test, ρ > 0.3, P < 0.01, df > 55, Supplementary Table.
S5). However, such incremental tendency was disrupted when
the stimulation frequencies were above 40 Hz (Supplementary
Fig. S3-S4). The abnormal change in the sideways speed and
heading angle of the beetle at these high frequencies might
imply a strong response of the beetle from its sense of being
endangered in which the beetle often fell on the side and turned
as moving too fast for escaping.
Besides the sideways walking induced by the stimulation of
individual elytron, the beetle was found to perform a forward
acceleration when both of its elytra were stimulated
simultaneously (Fig. 6A, N = 4 beetles, n = 85 trials, t-test, P <
0.02, df > 12, Supplementary Table. S3). The beetle also
maintained its orientation throughout the stimulation (Fig. 6B,
Fig. 5
. Response of the beetle to the electrical stimulation of its individual
elytron (N = 4 beetles, n = 186 trials). (A)
The trajectories of the beetle induced
by the electrical stimulation. The beetle moved sideways contralaterally to the
side of stimulus. The gray curves denote the section of none-
stimulation
period, whereas the red and green curves show the trajectories elicited by the
right and left elytron stimulation, respectively. (B)
The representative change
in heading angle of the beetle under the e
lectrical stimulation at 20 Hz. The
beetle generally maintained its orientation throughout the stimulus. (C)
The
representative sideways speed of the beetle at 30 Hz. The sideways speed of
the beetle increased and maintained at its maximal level during th
e
stimulation. (D) The graded response of the sideways velocity. The
induced
sideways walking speed was in proportion to the stimulation frequencies from
10 Hz to 40 Hz. The red and green lines represent the stimulation of the right
and left elytron, respe
ctively. The error bars denote the standard deviation of
the induced speed. The pulse train was set as 1.5 V, 5 ms pulse-
width, and 1 s
duration.
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Transactions on Medical Robotics and Bionics
TMRB-04-20-OA-0130 6
P > 0.40, df > 12, Supplementary Table. S4). The heading
change at 30 Hz, for example, was as low as -1.03 ± 12.11
degree (Fig. 6B, Supplementary Fig. S5). The forward speed of
the insect rapidly increased once the stimulus was triggered
(Fig. 6C and Supplementary Fig. S6). Like the sideways
walking, the graded control of this forward motion was
achieved by varying the stimulation frequency (Spearman’s
correlation test, ρ = -0.41, P < 0.01, df = 55, Supplementary
Table. S5). The relationship between the two factors however
was an inverse proportion in that the induced speed decreased
when the frequency was elevated (Fig. 6D). The frequency
increasing from 10 Hz to 40 Hz, for instance, reduced the
elicited forward velocity from 50.55 ± 9.48 mm/s to 37.41 ±
10.96 mm/s.
Achieving the sideways and forward walking through the
electrical stimulation of the insect’s elytra would complement
the controllability of the state-of-the-art cyborg beetles.
Furthermore, the graded control of these movements together
with that of the established turning and backward walking
would contribute to the development of a closed-loop system to
precisely navigate cyborg beetles.
C. Power consumption
The electrical stimulation of the elytra had remarkably low
power consumption. Each stimulus drew around 150 µW from
the power supply (Fig. 7). The energy saved from such a low
energy consumption could be utilized by the electronic
backpack to implement other tasks such as wireless
communication or environmental data collection.
IV. C
ONCLUSION
The paper presented the approach of using the electrical
stimulation of the insect’s elytra to initiate the sideways and
forward walking to complement the controllability of cyborg
beetles. The velocity of the two elicited movements was found
to have graded control using the stimulation frequency.
Moreover, the power consumption for this elytra stimulation
was remarkably low. These capabilities along with a suitable
miniature backpack equipped with position and environmental
Fig. 6
= 4 beetles, n = 85 trials). (A)
stimulated simultaneously. (B)
orientation unchanged throughout the stimulus. (C)
forward speed of the beetle at 30 Hz. Once the electrical stim
to both elytra, the beetle accelerated its forward velocity. (D)
black lines indica
was set as 1.5 V, 5 ms pulse-width, and 1 s duration.
Fig. 7. Power consumption of the elytra stimulation. (Top)
The stimulation
pulse train. The amplitude, pulse width and frequency of the stimulus was 1.5
V, 5 ms and 20 Hz, respectively. (Bottom)
The profile of the current driven by
the stimulus. The energy consumed by the elytra stimulation was around 150
µW for an 1s long during of the stated stimulus.
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Transactions on Medical Robotics and Bionics
TMRB-04-20-OA-0130 7
sensors would aid the future development of autonomous
ambulatory cyborg beetles that can search for lives.
A
CKNOWLEDGMENT
This work has been supported by the Singapore Ministry of
Education (MOE2017-T2-2-067). T.T. Vo-Doan is currently
supported by Human Frontier Science Program Cross-
disciplinary Fellowship. The authors offer their appreciation to
Dr. Poon Kee Chun for proofreading the paper, Mr. Chew Hock
See, Ms. Kerh Geok Hong, Mr. Tan Kiat Seng, Ms. Chia Hwee
Lang, Mr. Roger Tan Kay Chia at School of MAE, NTU, and
Prof. Andrew D. Straw at University of Freiburg for their
continuous support in setting up and maintaining the research
facilities.
R
EFERENCES
[1] R. Holzer, and I. Shimoyama, “Locomotion control of a bio-robotic
system via electric stimulation,” International Conference on Intelligent
Robots and Systems, vol. 3, pp. 1514-1519, 7-11 Sep 1997, 1997.
[2] T. E. Moore, S. B. Crary, D. E. Koditschek, and T. A. Conklin, “Directed
locomotion in cockroaches: biobots,” Acta entomologica slovenica, vol.
6, no. 2, pp. 71-78, 1998.
[3] M. M. Maharbiz, and H. Sato, “Cyborg beetles,” Scientific American,
vol. 303, no. 6, pp. 94-99, 2010.
[4] V. Karthik, and B. G. Yogesh, “Locomotion response of airborne,
ambulatory and aquatic insects to thermal stimulation using
piezoceramic microheaters,” Journal of Micromechanics and
Microengineering, vol. 21, no. 12, pp. 125002, 2011.
[5] T. Latif, and A. Bozkurt, “Line following terrestrial insect biobots,” 2012
Annual International Conference of the IEEE Engineering in Medicine
and Biology Society, pp. 972-975, 2012.
[6] J. C. Erickson, M. Herrera, M. Bustamante, A. Shingiro, and T. Bowen,
“Effective stimulus parameters for directed locomotion in Madagascar
hissing cockroach biobot,” PloS one, vol. 10, no. 8, pp. e0134348, 2015.
[7] C. J. Sanchez, C.-W. Chiu, Y. Zhou, J. M. González, S. B. Vinson, and
H. Liang, “Locomotion control of hybrid cockroach robots,” Journal of
the Royal Society Interface, vol. 12, no. 105, pp. 20141363, 2015.
[8] T. T. Vo Doan, M. Y. Tan, X. H. Bui, and H. Sato, “An Ultralightweight
and Living Legged Robot,” Soft Robotics, 2017.
[9] H. Sato, Tat T. Vo Doan, S. Kolev, Ngoc A. Huynh, C. Zhang, Travis L.
Massey, J. van Kleef, K. Ikeda, P. Abbeel, and Michel M. Maharbiz,
“Deciphering the Role of a Coleopteran Steering Muscle via Free Flight
Stimulation,” Current Biology, vol. 25, no. 6, pp. 798-803, 2015.
[10] K. Mann, T. L. Massey, S. Guha, J. Van Kleef, and M. M. Maharbiz, "A
wearable wireless platform for visually stimulating small flying insects."
pp. 1654-1657.
[11] F. Tedeschi, and G. Carbone, “Design issues for hexapod walking
robots,” Robotics, vol. 3, no. 2, pp. 181-206, 2014.
[12] A. Bozkurt, E. Lobaton, and M. Sichitiu, “A Biobotic Distributed Sensor
Network for Under-Rubble Search and Rescue,” Computer, vol. 49, no.
5, pp. 38-46, 2016.
[13] B. Blaesing, and H. Cruse, “Stick insect locomotion in a complex
environment: climbing over large gaps,” Journal of Experimental
Biology, vol. 207, no. 8, pp. 1273-1286, 2004.
[14] R. E. Ritzmann, R. D. Quinn, and M. S. Fischer, “Convergent evolution
and locomotion through complex terrain by insects, vertebrates and
robots,” Arthropod Structure & Development, vol. 33, no. 3, pp. 361-
379, 2004.
[15] F. Sanfilippo, J. Azpiazu, G. Marafioti, A. A. Transeth, Ø. Stavdahl, and
P. Liljebäck, “Perception-driven obstacle-aided locomotion for snake
robots: the state of the art, challenges and possibilities,” Applied
Sciences, vol. 7, no. 4, pp. 336, 2017.
[16] F. Cao, C. Zhang, T. T. Vo Doan, Y. Li, D. H. Sangi, J. S. Koh, N. A.
Huynh, M. F. B. Aziz, H. Y. Choo, K. Ikeda, P. Abbeel, M. M. Maharbiz,
and H. Sato, “A Biological Micro Actuator: Graded and Closed-Loop
Control of Insect Leg Motion by Electrical Stimulation of Muscles,”
PLOS ONE, vol. 9, no. 8, pp. e105389, 2014.
[17] E. Whitmire, T. Latif, and A. Bozkurt, “Kinect-based system for
automated control of terrestrial insect biobots,” 35th Annual
International Conference of the IEEE Engineering in Medicine and
Biology Society (EMBC), pp. 1470-1473, 2013.
[18] T. T. V. Doan, Y. Li, F. Cao, and H. Sato, "Cyborg beetle: Thrust control
of free flying beetle via a miniature wireless neuromuscular stimulator."
pp. 1048-1050.
[19] T. T. V. Doan, and H. Sato, “Insect-machine hybrid system: remote radio
control of a freely flying beetle (Mercynorrhina torquata),” JoVE
(Journal of Visualized Experiments), no. 115, pp. e54260, 2016.
[20] L. Yao, C. Feng, D. Tat Thang Vo, and S. Hirotaka, “Controlled banked
turns in coleopteran flight measured by a miniature wireless inertial
measurement unit,” Bioinspiration & Biomimetics, vol. 11, no. 5, pp.
056018, 2016.
[21] Y. Li, J. Wu, and H. Sato, “Feedback Control-Based Navigation of a
Flying Insect-Machine Hybrid Robot,” Soft robotics, 2018.
[22] F. Cao, C. Zhang, H. Y. Choo, and H. Sato, “Insect–computer hybrid
legged robot with user-adjustable speed, step length and walking gait,”
Journal of The Royal Society Interface, vol. 13, no. 116, 2016.
[23] F. Cao, and H. Sato, “Insect–Computer Hybrid Robot Achieves a
Walking Gait Rarely Seen in Nature by Replacing the Anisotropic
Natural Leg Spines with Isotropic Artificial Leg Spines,” IEEE
Transactions on Robotics, 2019.
[24] D. L. Le, Ferdinandus, C. K. Tnee, T. T. Vo Doan, S. Arai, M. Suzuki,
K. Sou, and H. Sato, “Neurotransmitter-Loaded Nanocapsule Triggers
On-Demand Muscle Relaxation in Living Organism,” ACS Applied
Materials & Interfaces, vol. 10, no. 44, pp. 37812-37819, 2018/11/07,
2018.
[25] H. Sato, C. Berry, Y. Peeri, E. Baghoomian, B. Casey, G. Lavella, J.
VandenBrooks, J. Harrison, and M. Maharbiz, “Remote radio control of
insect flight,” Frontiers in Integrative Neuroscience, vol. 3, no. 24, 2009-
October-05, 2009.
[26] J. Cole, F. Mohammadzadeh, C. Bollinger, T. Latif, A. Bozkurt, and E.
Lobaton, "A study on motion mode identification for cyborg roaches."
pp. 2652-2656.
[27] C. M. Comer, L. Parks, M. B. Halvorsen, and A. Breese-Terteling, “The
antennal system and cockroach evasive behavior. II. Stimulus
identification and localization are separable antennal functions,” Journal
of Comparative Physiology A, vol. 189, no. 2, pp. 97-103, 2003.
[28] S. Ye, V. Leung, A. Khan, Y. Baba, and C. M. Comer, “The antennal
system and cockroach evasive behavior. I. Roles for visual and
mechanosensory cues in the response,” Journal of Comparative
Physiology A, vol. 189, no. 2, pp. 89-96, 2003.
[29] A. Dirafzoon, T. Latif, F. Gong, M. Sichitiu, A. Bozkurt, and E. Lobaton,
“Biobotic motion and behavior analysis in response to directional
neurostimulation,” IEEE International Conference on Acoustics, Speech
and Signal Processing (ICASSP), pp. 2457-2461, 5-9 March 2017, 2017.
[30] J. M. Camhi, and W. Tom, “The escape behavior of the cockroach
Periplaneta americana. I. Turning Response to Wind Puffs,” Journal of
comparative physiology, vol. 128, no. 3, pp. 193-201, 1978.
[31] J. M. Camhi, W. Tom, and S. Volman, “The escape behavior of the
cockroach Periplaneta americana. II. Detection of Natural Predators by
Air Displacement,” Journal of comparative physiology, vol. 128, no. 3,
pp. 203-212, 1978.
[32] P. Domenici, D. Booth, J. M. Blagburn, and J. P. Bacon, “Cockroaches
Keep Predators Guessing by Using Preferred Escape Trajectories,”
Current Biology, vol. 18, no. 22, pp. 1792-1796, 2008/11/25/, 2008.
[33] P. Domenici, D. Booth, J. M. Blagburn, and J. P. Bacon, “Escaping away
from and towards a threat: The cockroach’s strategy for staying alive,”
Communicative & Integrative Biology, vol. 2, no. 6, pp. 497-500, 2009.
[34] J. Okada, and Y. Toh, “Antennal system in cockroaches: a biological
model of active tactile sensing,” International Congress Series, vol.
1269, pp. 57-60, 8//, 2004
[35] J. Hwangbo, J. Lee, A. Dosovitskiy, D. Bellicoso, V. Tsounis, V. Koltun,
and M. Hutter, “Learning agile and dynamic motor skills for legged
robots,” Science Robotics, vol. 4, no. 26, pp. eaau5872, 2019.
[36] P. Ramdya, P. Lichocki, S. Cruchet, L. Frisch, W. Tse, D. Floreano, and
R. Benton, “Mechanosensory interactions drive collective behaviour in
Drosophila,” Nature, vol. 519, no. 7542, pp. 233-236, 2015.
[37] John C. Tuthill, and Rachel I. Wilson, “Mechanosensation and Adaptive
Motor Control in Insects,” Current Biology, vol. 26, no. 20, pp. R1022-
R1038, 2016/10/24/, 2016.
[38] John C. Tuthill, and Rachel I. Wilson, “Parallel Transformation of
Tactile Signals in Central Circuits of Drosophila,” Cell, vol. 164, no. 5,
pp. 1046-1059, 2016/02/25/, 2016.
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Transactions on Medical Robotics and Bionics
TMRB-04-20-OA-0130 8
[39] B. D. DeAngelis, J. A. Zavatone-Veth, A. D. Gonzalez-Suarez, and D.
A. Clark, “Spatiotemporally precise optogenetic activation of sensory
neurons in freely walking Drosophila,” eLife, vol. 9, pp. e54183, 2020.
Authorized licensed use limited to: UNIVERSITAET FREIBURG. Downloaded on June 26,2020 at 06:12:09 UTC from IEEE Xplore. Restrictions apply.

Supplementary resource (1)

... More specifically, with a simple add-on electronic circuit, these systems can retain the outstanding locomotory skills of the insect platform to favor the complex and unpredictable post-calamity terrains . At the same time, they can still provide various controllability with low power consumption (i.e., a few 100 µW) (Cao et al. 2014;Nguyen et al. 2020;Vo Doan et al. 2017). Moreover, insect-machine hybrid systems are environmentally friendly, have a low production cost, and allow a sustainable supply since most insect bodies are biodegradable and the insects are naturally reproducible. ...
... Besides, the well-established stimulation methods, which are greatly diverse in both regulated movements and insect species, provide flexible choices to cope with the desired locomotion control from the diverse insect kingdom. For example, a variety of motions (e.g., directional turns, forward/backward/sideways walks) in darkling beetles (Zophobas morio) and cockroaches (Periplaneta americana, Gromphadorhina portentosa) can be induced by stimulating their sensory systems like antennae, elytra, and cerci (Dirafzoon et al. 2017;Latif and Bozkurt 2012;Nguyen et al. 2020;Tran-Ngoc et al. 2021;Vo Doan et al. 2017). These induced motions were discussed as reassembling the insects' behavioral responses when the same sensory organs were naturally evoked (Camhi and Tom 1978;Ye et al. 2003). ...
... In tandem with these insect-centric approaches, researchers are also looking for solutions from engineering perspectives, for example, the control algorithm for insect-machine hybrid systems. Many insect species reportedly exhibited graded locomotion responses driven by electrical stimulation (Cao et al. 2014;Latif et al. 2016;Nguyen et al. 2020;Vo Doan et al. 2017). Such graded reactions suggest a potential solution to overcome the demand for an optimal stimulus by utilizing a feedback control system in which the controllers can finetune the insects' desired responses (Cao et al. 2014;Liu et al. 2022). ...
Article
While bio-inspired and biomimetic systems draw inspiration from living materials, biohybrid systems incorporate them with synthetic devices, allowing the exploitation of both organic and artificial advantages inside a single entity. In the challenging development of centimeter-scaled mobile robots serving unstructured territory navigations, biohybrid systems appear as a potential solution in the forms of terrestrial insect-machine hybrid systems, which are the fusion of living ambulatory insects and miniature electronic devices. Although their maneuver can be deliberately controlled via artificial electrical stimulation, these hybrid systems still inherit the insects’ outstanding locomotory skills, orchestrated by a sophisticated central nervous system and various sensory organs, favoring their maneuvers in complex terrains. However, efficient autonomous navigation of these hybrid systems is challenging. The struggle to optimize the stimulation parameters for individual insects limits the reliability and accuracy of navigation control. This study overcomes this problem by implementing a feedback control system with an insight view of tunable navigation control for an insect-machine hybrid system based on a living darkling beetle. Via a thrust controller for acceleration and a proportional controller for turning, the system regulates the stimulation parameters based on the instantaneous status of the hybrid robot. While the system can provide an overall success rate of ~71% for path-following navigations, fine-tuning its control parameters could further improve the outcome’s reliability and precision to up to ~94% success rate and ~1/2 body length accuracy, respectively. Such tunable performance of the feedback control system provides flexibility to navigation applications of insect-machine hybrid systems.
... More specifically, with a simple add-on electronic circuit, these systems can retain the outstanding locomotory skills of the insect platform to favor the complex and unpredictable post-calamity terrains [15]. At the same time, they still can provide various controllability with low power consumption (i.e., a few 100 µW [16][17][18]). Moreover, due to the biodegradable characteristic and the natural reproduction ability, cyborg insects are environmentally friendly, have a lowcost assembly, and guarantee a sustainable supply. ...
... Besides, the well-established stimulation methods, which are greatly diverse in both regulated movements and insect species, provide flexible choices to cope with the desired locomotion control from the diverse insect kingdom. For example, a variety of motions (e.g., directional turns, forward/backward/sideways walks) in darkling beetles (Zophobas morio) and cockroaches (Periplaneta americana, Gromphadorhina portentosa) can be induced by stimulating their sensory systems like antennae, elytra, and cerci [17,18,21,25,27]. These induced motions were discussed as reassembling the insects' behavioral responses when the same sensory organs were naturally evoked [28,29]. ...
... In tandem with these insect-centric approaches, researchers are also looking for solutions under engineering perspectives, for example, the control algorithm for cyborg insects. Many insect species reportedly exhibited various graded locomotion responses driven by electrical stimulation [16][17][18]35]. Such graded reactions suggest a potential solution to overcome the demand of an optimal stimulus by utilizing a feedback control system, in which the controllers can fine-tune the insects' desired responses [16,36,37]. ...
Preprint
Full-text available
Terrestrial cyborg insects were long discussed as potential complements for insect-scale mobile robots. These cyborgs inherit the insects' outstanding locomotory skills, orchestrated by a sophisticated central nervous system and various sensory organs, favoring their maneuvers in complex terrains. However, the autonomous navigation of these cyborgs was not yet comprehensively studied. The struggle to select optimal stimuli for individual insects hinders reliable and accurate navigations. This study overcomes this problem and provides a detailed look at the terrestrial navigation of cyborg insects (darkling beetle) by implementing a feedback control system. Via a thrust controller for acceleration and a proportional controller for turning, the system regulates the stimulation parameters depending on the beetle's instantaneous status. Adjusting the system's control parameters allows reliable and precise path-following navigations (i.e., up to ~94% success rate, ~1/2 body length accuracy). Also, the system's performance can be tuned, providing flexibility to navigation applications of terrestrial cyborg insects. Video: https://youtu.be/p00mfxFo7VY
... During the pandemic, the teleoperation system is used for various applications such as industrial robot control [17], medical-surgical operation [18], and mobile robot control for multiple applications [19]. Previously, different cyborg insects were used to search and rescue operations, but most cyborg insects control systems based on a local area network (LAN) such as Bluetooth, Wi-Fi, and Radiofrequency (RF) [20,21]. However, no study has found to control the cyborg insect using a teleoperation system from one country to another country. ...
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... The motor actions of the insect can be controlled by sending the electrical stimulus directly from the backpack terminals to the muscles or neural clusters through implanted electrodes. Precise walking gaits in beetles were achieved by stimulating the leg muscles [30,31] while turning, backward, forward, and sideways walking were driven by stimulating the mechanosensory organs (e.g., antennae, cercus, and elytra) and ganglion in beetles [32,33] and cockroaches [34][35][36]. Flight initiation and cessation of the beetles were achieved by stimulating optic lobes [27] and indirect flight muscles [37] while stimulating direct flight muscles enable steering control in flight [25,27,28]. ...
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