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IVC RAISE 2020 IOP Publishing
IOP Conf. Series: Materials Science and Engineering 1055 (2021) 012001 doi:10.1088/1757-899X/1055/1/012001

Snake Robots for Rescue Operation

V Arun Kumar1*, Adithya B2, P T Bijoy Antony2

1
Assistant Professor, Department of Mechatronics Engineering, Kongu Engineering
College, Perundurai, Erode, India.
2
UG Scholar, Department of Mechatronics Engineering, Kongu Engineering College,
Perundurai, Erode, India.
*E-mail: arunkumar@kongu.ac.in

Abstract.The motivation for snake robots originates from natural snakes. Snakes show better
versatility abilities and can move over basically any kind of landscape, including limited and
restricted spaces. Like a snake, robot has an exceptionally expressed robot controller arm with
the capacity of giving its own drive. Wheel-less, limbless secluded Snake-like robot (Snake
robot) has superior capacities in flexibility and adoptability to nature in examination with the
most haggled vehicles. Some helpful highlights of snake-like robots incorporate smaller size of
the cross-sectional regions, steadiness, capacity to work in troublesome landscape, great
footing, high redundancy and complete fixing of the inside systems. Our model consists of
multiple links joined together to create propulsion on its own in a spatial environment. The first
link (head) can have various configurations like camera, gripper, etc. This makes the snake
robot ideal for search and rescue operation.

Keywords: Snake robot, bio-inspired robotics, rescue, serpentine robot

1. Introduction and background study

Wheel is the mother of all invention, wheeled mechanism is the key to most of the ground-based
transportation of today’s date. Comparatively in smooth surfaces, such mechanisms are performing
well with high speeds and have sensible steering ability. Rougher terrain makes it tougher, if not
possible, for wheeled mechanisms to maneuver. Snake is one amongst the creatures in nature that
exhibit glorious quality in numerous terrains. It can move through slender passages and jump on rough
ground. This unique mobility quality property is recreated in robots that look and move like snakes.
These snake robots most frequently have a high variety of degrees of freedom (DOF) and they can
move in the absence of active wheels or legs. At some point of time, snake robots might play a vital
role in search and rescue operations, fire-fighting, examination and maintenance. The extremely
articulated body permits the snake robot to traverse tough terrains like folded buildings or the chaotic
situation caused by an automobile collision in tunnels. The snake robot could move through the
intervals between collapsed buildings looking for people whereas at the same time transferal
installation in conjunction with little amounts of food and water to anyone treed by the shattered
building. Moreover, the snake robots will be used for examination and maintenance of complicated
and probably risky areas of business plants like nuclear facilities. In urban areas, it might examine the
sewage works searching for leaks or aid fighters.
The snake mechanism is a lot of sturdy to mechanical failures thanks to high redundancy and
modularity. The drawback is its restricted payload capability, poor power potency and a really sizable
amount of degrees of freedom that have to be compelled to be controlled. This desk work which
manages dynamic and kinematic demonstrating of a wheel-less snake robot was proposed utilizing

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IVC RAISE 2020 IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1055 (2021) 012001 doi:10.1088/1757-899X/1055/1/012001

MATLAB/Simulink. This model can possibly adjust with nature. Also, the connection between the
quantity of connections and the forward speed is examined in this investigation. The snake robot can
move quicker in conditions where the erosion is huge and this can be proved from the re-enactment
results. The outcome additionally shows that the forward speed is proportionately corresponding to the
quantity of connections[1].
A snake robot which consists of enclosed actuators and has a modular architecture was designed
[2]. It has a high torque output module and efficient usage of available power. It also has bi-stable
brake to hold the robot in its position without drawing power. A series elastic actuated (SEA) snake
robot which consists of 1-DOF modules in a series chain was developed. In this, each module allows a
full 180 degree rotation [3]. Snake robots can be used to navigate through pipe networks which cannot
be achieved using wheeled robots. Hence a snake robot which automatically adapts to the shape of its
environment such as changes in pipe diameter and junctions was developed. A closed loop control is
used in order to achieve high level robot behaviour. This provides a better result while traversing
through pipes [4].
A method which deals with modelling the rolling motion of snake robot was proposed [5]. The
rolling motion was represented by adopting Bellows model. A rolling hump gait was designed using
the concept of composing shapes which enables the snake robot to climb over obstacles and move on
bumpy terrains. A design was created for the gait of snake robot which is useful to move in
complicated environment [6]. Two strides were created in this work, one for moving over a rib on a
line and another step called crawler walk which can move across harsh territory. A technique which
permits the snake robot to ascend stepping stools was proposed [7]. The snake robot has a smooth
surface shape which is created through development of pectinate - shaped pieces of the connections.
The climbing movement is produced by mix of move control and hanging movement. The experiments
proved that the robot can climb both straight and inclined ladders.
The dynamic and kinematics modelling of a planar, underwater snake robot was developed [8]. A
simulation model of serpentine and eel-like motion pattern was presented which is modelled by
considering the combinations of forces acting on the snake robot. The simulation is independent of
number of robot links. A waterproof snake robot named Mamba was proposed [9]. It can quantify the
natural contact powers acting along its body. This is accomplished by utilizing strain check based
power/force sensors which are introduced in each joint module of the robot. A method in which a
snake robot possess both snake-like and bipedal motion was modelled [10]. This reconfigurable robot
can transform between snake and multiple walking configurations without any attachment or
detachment of its modules. The goal is to achieve efficient walking along the rough and uneven
terrains.
A control framework for snake robot which uses extend sensor information to stay away from
crashes was proposed [11,12]. The administrator gives the ideal speed of the initial connection through
a regulator, and at that point, the regulator naturally ascertains the impact shirking between ensuing
connections and obstructions. A sound-based confinement technique which appraises the robot area
and pipeline map with an IMU was created [14]. This technique finds beneficial as the GPS and other
odometry-based confinement strategies are denied in a pipeline because of its exactness. The proposed
strategy utilizes time of flight (ToF) of sound waves to gauge the separation. This technique at the
same time gauges the area of the robot and pipeline map by consolidating the separation acquired by
the ToF and direction assessed by the IMU.
Most of the snake robots described here are wheeled snake robots. Wheels cannot move between
rubbles and rocky terrains. So, they cannot be used in rugged and uneven terrains. These robots have
circular or cylindrical gaits which have higher possibilities to roll over in highly inclined surfaces. In
addition to this, these robots do not have grippers to carry the necessary payloads.
During disasters like earthquake people struck in the rubbles lose their lives mainly due to
suffocation and thirst. The rescue department needs to clear the rubbles to get the people out within a
short period of time to save their lives. Due to this the rescue department has to take drastic measures
to save them and even though they do their best service some people lose their liver due to suffocation.
To avoid this the rescue department sends hose to the struck person to supply air and water. This is not
possible if the path to reach the struck person is complex. In this case mobile robots can be employed
to take the hose to the target through the gaps in the rubbles. Most of the mobile robot move by using
wheels or legs. However, the wheels cannot roll in uneven terrains and legged robots with a

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IVC RAISE 2020 IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1055 (2021) 012001 doi:10.1088/1757-899X/1055/1/012001

considerable payload are difficult to design in small size. Hence it is possible for a snake robot with a
robust design and a gripper to carry the hose to the people who are struck between the rubbles.

2. Proposed method

2.1. Proposed solution

The objective of this project is to assist the rescue department in its operations. The snake robot can
crawl through most of the small gaps in the rubbles. This ability will let it be more useful to the rescue
operation than other mobile robots. The snake robot can have a camera and a gripper in its first link,
this will allow the snake robot to search and find whether people are struck inside the rubbles or not.
The gripper will allow this robot to take a hose to the target for air and water through the gaps in the
rubbles if necessary. The robot can be wired as well as wireless. The robot can be shielded from
external environment by adding a cover or shield around its body. This will allow to bot to be operated
in swamps or slurry environment. The robot can be operated or controlled wirelessly by using
Bluetooth. The communication system can be changed to operate by using Wi-Fi or RF signals or
ZigBee [13]. All components in this robot allow modularity. The robot is made of multiple links and
joints controlled individually by separate servo motors. The movement of the robot is achieved by
self-propulsion due to the movements of individual links in a specific method. The servo motors can
be changed to more powerful motors to accommodate the user’s needs. The length of the robot can be
changed on the spot in a short time based on the need of the rescue operation. The figure 1 shows the
flow chart of the work.

Figure 1. Flow Chart of the snake robot design

2.2. Working principle

The snake robot consists of number of links and joints. Each link consists of a multipurpose servo
bracket, short U-shaped clamp, L-shaped interlink and a servo motor. The brackets, clamps and
interlinks are used for joining the multiple servo motors into a single robot. The servo motors are
controlled individually to produce a self-propelling motion. The servo motors rotation must be
perfectly coordinated in a specific pattern to create a self-propelling motion. Each motor of the robot is
individually controlled by using the controller (ATmega 328p). Servo motors angle of rotation must be
unique for each link. This is achieved by multitasking algorithm program.


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IVC RAISE 2020 IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1055 (2021) 012001 doi:10.1088/1757-899X/1055/1/012001

2.2.1. Inch worm motion. This motion uses the movement of a worm as a model for the snake robots
motion. A worm moves by moving its back end of its flexible body to create an arc and propagate that
arc to its front end of its body. This allows the worm to move through tight gaps and move easily. The
same concept is used in snake robots, First the last link is moved forward by rotating the send servo
motor from the end while the two adjacent motors rotate to keep the stability. Next step the third motor
from the end propagates the arch created by the previous motor while the last motor provides friction
by aligning itself to the ground or base surface. This process is repeated until the created arch reaches
the front link. The robot moves forward due to the friction created by the remaining links by aligning
themselves to the base or surface. To move the robot in reverse direction the process is done in reverse
order starting by creating an arch in the front end.

2.2.2. Sideway Motion. This model is derived from the actual motion of the snake. Snakes use their
flexible spine to create motion mainly based on the friction between its body and surface. Sequence of
the motion of the snake is as follows, First the snake creates an arch in the horizontal plane and lifts its
front end and straightens its body. But an actual snake can create these multiple arches throughout its
whole body. This allows it to move in a rapid motion. Snake robot can be programmed to move in this
model as well. This movement is really a blend of the serpentine and rectilinear movements depicted
previously. To accomplish this movement, the robot must be reconfigured. A side section interfacing
one fragment to the C-section of the following portion is unscrewed and turned 90 degrees. This is
done along the whole length of the snake. Hence servos 1, 3, 5 will be situated concerning serpentine
movement and servos 2, 4, 6 will be situated with respect to rectilinear movement. Side winding
movement is accomplished by sending a flat cosine wave down the odd numbered servos and a
vertical cosine wave (balance from the level wave by 90 degrees) down the even numbered servos.
Thus, the sideways movement is accomplished. The figure 2 shows the side way motion of a
snake[16].

Figure 2. Side Way Motion

3. Components used and modelling

3.1. Arduino UNO (ATmega328p)

The Arduino UNO is a microcontroller board upheld with the chip ATmega328P microcontroller and
created by Arduino.cc. The board is provided with sets of advanced and simple information/yield (I/O)
pins which will be interfaced to change the broadening sheets (shields) and elective circuits. The board
has six simple pins, fourteen advanced pins and programmable with the Arduino IDE (Integrated
Development Environment) by means of a sort B USB link. It will be battery-fueled by a USB link or
by an outer 9V battery, regardless of its acceptance of voltages somewhere in the range of seven and
twenty volts. Furthermore, it is equivalent to the Arduino Nano and Leonardo.

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IVC RAISE 2020 IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1055 (2021) 012001 doi:10.1088/1757-899X/1055/1/012001

The prearranged ATmega328 goes ahead the Arduino Uno with a boot loader that empowers
transferring new code thereto while not the work of an outer equipment engineer. The correspondence
is encouraged with the first STK500 convention.

3.2. Servo motor (MG995)

A servo engine is an electrical gadget which can push or pivot an item with accuracy. A servo engine is
normally used if an object needs to be turned to a particular edge, or to be rotated. We can get an
exceptionally high force servo engine in a little and light weight bundles. The number of servo motors
is divided into 2 parts. Here, totally six servo motors are used, in which 3 of them are used to provide
vertical movement and other 3 provide horizontal movement. These motors are controlled individually
by Arduino. Based upon the commands given by Arduino to the servo, appropriate motion of the snake
robot is achieved.

3.3. HC-05
HC - 05 is the Bluetooth module and complies as a MASTER/SLAVE module. Of course, the works
setting is SLAVE. The Role of the module (Master or Slave) will be sorted out exclusively by AT
COMMANDS. The slave modules can't start an alliance to an alternate Bluetooth gadget, anyway will
make due with associations. Ace module will start a connection to elective gadgets. The client will
utilize it simply for a port substitution to find out alliance between MCU and GPS, PC to an installed
framework, and so forth.

3.4. Camera
Remote cameras will be cameras that communicate a video and sound sign to a remote collector
through a radio band. Remote cameras require in any event one link or wire for power. Video can be
taken to PC through Video catch/TV tuner for picture handling as well. The camera can be connected
to any surface by utilizing fastener and nut or screws.

3.5. Multipurpose servo brackets

Multipurpose servo brackets are specially designed components made of aluminum or plastic to hold servo
motors. Due to its design the servo motor gets a full support while it operates. This bracket is used for
connecting the servo motor to the L shaped interconnect servo bracket. These brackets are made up of
aluminum to reduce the weight of the snake robot’s mechanical structure. These brackets contain drilled
holes to connect with the other components by using screws. The bracket is provided with large number of
extra holes to provide modularity and allows the user to change its configuration easily.

3.6. Short U-shaped servo bracket

This section is utilized for associating one servo section to another. It is explicitly intended to append
to a servo engine's pole. The short U-formed servo section is connected to the servo engine's pole by
utilizing screws. This section is associated with the L formed interconnect servo section. This section
is made of aluminum to lessen the heaviness of the robot.

3.7. L-shaped interconnect servo bracket

Interconnect servo sections are uniquely designed in aluminum to interface servo sections to short U-
shaped servo sections. This section is utilized for associating the servo engine to short U-formed servo
section. The L-formed interconnect servo section is appended to the multipurpose servo sections by
utilizing screws. This section is made of aluminum to reduce the heaviness of the robot.

3.8. Parallel jaw gripper

Parallel Jaw Robotic Gripper gives the best grasp on load. It is adaptable with RKI-1204 and RKI-
1211 servos [15]. Gripper is made of Aluminum Alloy having high elasticity with a general opening
range of 55 mm.

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IVC RAISE 2020 IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1055 (2021) 012001 doi:10.1088/1757-899X/1055/1/012001

3.9. Bolts and nuts

It is regular to utilize fasteners and nuts in numerous applications with an expectation to hold segments
or things together tightly. Here and there the screw isn't utilized along with a nut, yet the nut is
generally utilized alongside a fastener. Stray pieces fill in as the principal segments in a few
development ventures as they give solid bonds that don't earn back the original investment under
incredible measures of weight. Screws and nuts can have a few unique styles and types, each fit to
coordinate the necessities of a specific application or the requirements of the activity.

3.10. Kinematic modelling

The snake robot comprises of N unbending connections of length 2l interconnected by N – 1
mechanized joints. The width of each connection isn't considered in the model. All N joins have a
similar mass m and snapshot of idleness J. The total mass of the snake robot is thus Nm. Uniform
dispersion of weight is guaranteed in each connection so that the connection CM (Center of Mass) is
arranged at its middle point (One length l ahead from the joint at each side). The figure 3 shows the
kinematic model for snake robot’s movement. The figure 3 shows the kinematic model for snake robot’s
motion.

Figure 3. Kinematic Model for Snake Robot

In the above equation, the robot’s global frame position i.e. p of the CM (Center of mass) is displayed
by equation(1)

(1)

The heading (direction) of the snake robot is characterized as the normal of the connection edges
which is given in the condition (2)

(2)

Every connection link in the system is fixed in the CM of the connection with x (divergent) and y
(normal) axes and the same are aligned in such a way with the worldwide x and y axis when the
connecting angle becomes zero. The rotation matrix from the worldwide edge to the casing of
connection is given in the equation (3)

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IVC RAISE 2020 IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1055 (2021) 012001 doi:10.1088/1757-899X/1055/1/012001

(3)

3.11. CAD modelling

The snake robot’s entire functionality depends on the design of its links and joints. These links must be
interchangeable and must be able to connect with each other to form a complete structure. The figure 4
shows the design of individual links. The figure 5 shows the complete design of the snake robot.

Figure 4. CAD Model of Links of the Snake Robot.

Figure 5. CAD Model of Snake Robot.

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IVC RAISE 2020 IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1055 (2021) 012001 doi:10.1088/1757-899X/1055/1/012001

3.12. Assembly
The snake robot consists of multiple links and joints which must be joined to form a whole robot. The
links are joined to each other by using fasteners (bolts and nuts) for modularity purposes. If there is
any need to extend the size of the robot, then the links can be easily added by attaching extra links by
using bolts and nuts. If there is any need to reduce the number of links in the robot, then links can be
easily removed by disengaging the bolts and nuts holding them. The snake robot is modular because of
its ability to integrate with many peripherals like gripper, camera, etc., to its links via bolt and nut. The
figure 6 shows the snake robot when a gripper is attached to its first link. These peripherals can be
controlled by using Arduino with appropriate program.

Figure 6. Complete Assembly of Snake Robot.

4. Feasibility study

4.1. Economic feasibility

The value of human life is more than any other things. Our government mobilizes large funds when
disasters like building collapse, earthquake or a child falling inside a bore well accidentally. Even then
sometimes the rescue team cannot save all lives because they don’t know where a person is struck and the
person dies due to suffocation. Compared to the lives of people the cost of this project is too small to even
bother with.

4.2. Operational feasibility

Any rescue bot must be very flexible, adaptable and must be able to move in any terrain through
obstacles. Since the proposed project is flexible, adaptable, modular, self-propelling, the snake robot is
the most suitable for rescue operation than any other robots ever designed. The robot is controlled
wirelessly so this allows the robot to enter an environment where it is dangerous for living beings.

4.3. Technical feasibility

The robot consists of multiple links and joints which can be controlled individually by using a servo motor.
The power supply for the robot can be used as wired as well as wireless. To control the motors Arduino uno
is used so the robot’s program can be edited very easily. The robot can be attached with any wireless
communication device for controlling the motion and to get the camera feeds.

5. Conclusion
The snake robot can assist the rescue department in rescue and surveillance operations because of its
adaptability, flexibility and modularity. The aid of the snake robot will greatly increase the possibility
of rescue of a being during disasters and the rescue department can use this robot in any environment.
The snake robots design can be improved if a single link can provide 3D actuation (pitch yaw and
roll). However, these links must be fabricated specifically for the snake robot. If that is done, snake
robot will be more versatile and will be more useful. This robot cannot be used for underwater

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IVC RAISE 2020 IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1055 (2021) 012001 doi:10.1088/1757-899X/1055/1/012001

applications but this can be achieved by providing sufficient casing for the gaits.Also it cannot carry
heavy loads with it. The additional peripherals can be designed specifically for snake robot and any
functionality can be achieved via snake robot. The snake robot can be used as an industrial
manipulator that can hold objects without any specific shape or size. These robots due to their higher
flexibility and adaptability can be used for inspection purposes in industries and pipelines. It can also
be used for surveillance in forest and military purposes.

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[10] Thakker R, Kamat A, Bharambe S, Chiddarwar S and Bhurchandi K M2014ReBiS -
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Automation(Anchorage, AK : IEEE) pp 691-696

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