STATEMENT OF INVENTION:
The present investigation discloses the fabrication as well as navigation of an underwater
robot for operating depth of 25 m. This robot can perform missions such as underwater
exploration and also monitoring of aqua lives in shallow water.
BACKGROUND OF INVENTION:
Field of invention
The present invention relates to prototype fabrication of underwater mobile robot. In
particular it is related to fabrication of a neutrally buoyant, hydrostatically stable and
automated underwater mobile robot. Moreover, the robot can monitor underwater
environment of 25m depth during navigation.
Background of invention
Massive advances in technology as well as human attraction towards autonomous vehicle
results in easy access to risk prone areas of world (air, surface or underwater). Such
vehicles must be responsive, adaptable, robust and also multitasking by nature. Now-a-
days, growth in researches on unmanned autonomous underwater robots leads towards
imminent deployment of undersea circumstances for various commercial, scientific,
defense and academic applications like long term observations, exploration of mines from
seabed, surveillance of ice-covered areas of ocean, taking videos of rare views of sea
floor, retrieval of ship wreckages in deep ocean and security of aqua lives etc. Due to
high water level pressure, deeper immersion may be life-threatening for human being.
Design of autonomous underwater vehicles for executing assembly of underwater tasks,
may exceed the use of human divers and small human-driven submarines.
The variety of tasks may include collections of ocean samples for a long time period or 3-
D mapping of underwater unknown hollows. As per diverse usages in a wide range,
shapes as well as configurations of an underwater vehicle are distinctive. Modern A'UVs
are also highly cost-effective. Apart from that autonomous underwater vehicles have to
be efficient enough to cope up with nonlinearities of dynamic behaviour as well as
uncertainties in hydrodynamic coefficients due to high frequency oscillations during
motion through an unspecified underwater environment. In another way, communication
of robot with workstation during underwater motion cannot be stimulated in a regular
manner due to significant external disturbance, low bandwidth of sensory and actuating
systems. So, achievement of high degree of autonomy to react in unexpected situations is
another important objective of the present research. The present research focuses on the
fabrication of an underwater mobile robot for visual monitoring of aqua lives as well as
underwater environment while navigating in shallow water of 25m depth.

Prior Art
• U.S. Pat. No. 7296530 to inventor Charles et al. discloses an unmanned swimming
vehicle which is capable of doing assessment, recognition and/or deactivation
of immersed substances. To operate at the surface level of water, this automated vehicle
includes a mother controller, self-propulsion, navigational ability, wireless
communication, and electrical energy generation systems like as other robots. The
developed unmanned vehicle is tethered with another small submersible robot by
electro-mechanical means.
• U.S. Pat. No. 20120289103 Al to inventor Hudson et al. relates more particularly to
hybrid unmanned underwater vehicles that can perform a variety of behaviors that
increase endurance and mission capability. Body of the vehicle contains a controller; a
vector thruster for propelling the body; deployable wings to traverse in ascending and
descending motion; a center-of-mass shifter for shifting a center-of-mass of the vehicle
to pitch up and pitch down; and one of a multi-stage buoyancy control system has
configured to adjust an apparent displacement of the unmanned underwater vehicle.
• Published patent application US 8511247 to inventor Tomoya Inoue discloses
an underwater traveling vehicle that is used for sea floor exploration, sea floor cable
laying, or cleaning of sea floor or a tank bottom, etc., and travels on an endless track
means which is rotatable and mounted to the vehicle body and a thruster is also
provided in the vehicle body.
• U.S. Pat. No. 8701584 to inventor Kalwa discloses an unmanned underwater vehicle
having sensor unit that can be used to acquire sensor information about surroundings
of the underwater vehicle. The invention also relates to a method for operating an
unmanned underwater vehicle in order to sense structures and contours of objects
under water as quickly and accurately as possible.
• Published patent application US 20110282536 A1 to inventor James et al. introduces a
vessel hull robot navigation subsystem and method for driving the robot which is
configured to clean and/or inspect the hull of a vessel. The navigation processor
controls the drive subsystem to maneuver the robot on the hull based on the fix data.
• Published patent application EP2237395 A1 to inventor Shimamura et al. relates to a
submersible electric motor assembly for underwater use which can provide heat
dissipation ability higher than that of conventional electric motors and they are
accommodated in a casing to make the coils water proof. The increased coil capacity
improves the output power / volume ratio of the electric motor, so that the electric
motor can be reduced in size.
• Published patent application 8655022 to inventor Kobayashi et al. discloses a system
and method for detecting accurately the position of an underwater vehicle which is
designed to inspect theinternal structures of a nuclear reactor. The invention is
especially suitable for detection of an underwater object placed in an environment in
which the object cannot be inspected visually.

• Published patent application 7778111 to inventor Hawkinson et al. discloses method
and system for underwater navigation which relates to methods for measuring position
and velocity while surveying underwater terrain that requires continuous and accurate
positioning and depth measurement information.
• U.S. Pat. No. 20060008137 A1 to inventor Magahdaripour et al. relates to the device
and its methodology for pictorial scrutiny of a configuration submerged in ocean for
example wreckages of ship hull. During navigation around the specific target location
or specified object, the built equipment is able to draw a three dimensional
fundamental map of targeted object in photo-mosaic form.
• U.S. Pat. No. 20120063262 A1 to inventor Imran discloses a self-propelled
buoy for monitoring and. communicating with divers and other underwater objects. The
buoy has capabilities to monitor a diver, obtain position information about the diver
and use that information to move itself to an effective range for continued monitoring.
The buoy can connect and communicate with a communication device attached to a
diver to communicate, position, biometric and other data. The system may comprise a
single or multiple buoys and can include an electrical storage .such as an electrical
battery.
• U.S. Pat. No. 20090216444 A1 to inventor Crowell describes the method and
apparatus to translate a positional fix of the float to an actual position of
an underwater vehicle. More particularly, one exemplary system provides a float
capable of receiving a position signal, such as a GPS signal, and translates the GPS fix
position offset of the underwater vehicle from the float so that the position of
the underwater vehicle is known. The underwater vehicle can also use sensors to
determine the positional offset of the vehicle from the float buoy.
• U.S. Pat. No. 5579285 to inventor Hubert unveils a specific tool and its methodology
for remote control as well as observation of semi-autonomous
underwater vehicles which are able to achieve one or more than one targeted
objectives, such as: to quantify physical or chemical parameters of the atmosphere or
for signaling the depth of the sea or more particularly for missions like surveillance
and exploration of sites on land or at sea located in the region of a predetermined
maritime zone, or else for missions of deception and counter-measures.

OBJECT OF THE INVENTION:
The present work is related to study and analysis of a fabricated automated underwater
mobile robot for operating depth of 25 m.
SUMMARY OF INVENTION:
The invention relates to prototype underwater mobile robot that can be used for
navigation as well as visual monitoring in shallow water. This robot associated with eight
thrusters is intended to achieve smooth translational motion at speed of ] .62 knots
(3km/hr.) (Forward-backward) and 0.54knots(1km/hr.) (Up-down) respectively and also
rotational speed of 1.57 rad/s at the surface of water and 1.3 rad/s under water. Motion
planning for multifunctional autonomous underwater robot up to 11m depth has been
approached here. The waterproofing of electronics and other sensitive elements for a
working system is also considered to be crucial. This robot prototype is a low cost one
and can be applied for academic research purpose.

Figure 1 shows the front view of the underwater mobile robot.
Figure 2 show the isometric view of the underwater mobile robot.
Figure 3 shows the rear view of the underwater mobile robot.
Figure 4 shows the side view of the underwater mobile robot.
Figure 5 shows the top view of the underwater mobile robot.
INDEX OF DRAWING REFERENCE NUMBER
1. Thrusters/Submersible Motors
2. Camera
3. Ultra bright LEDs
4. Control Module
5. Chassis
6. Perforated frame
7. Cable for Power Supply
DETAILED DESCRIPTION
The present invention provides a detailed methodology to construct a low cost
underwater mobile robot for operating in shallow water of 25m depth. The different
segments of the robot are as follows:
1. Thrusters
2. Motion (Translation and Rotation)
3. Control Module
4. Visual Sensor (Camera)
5. Frame with chassis
6. Communication with workstation
7. Cable Connection
8. Power Supply
9. Buoyancy Control
The detail description of the different parts of the underwater mobile robot is given
below:

1. Thrusters: Eight waterproof motors (230V AC, 50/60Hz, 45 W) are fastened with
designed frame. (Four Horizontal: Two for forward and other Two for backward
motion and Four Vertical: Two for up and other Two for down motion).
2. Motion (Translation and Rotation): This prototype underwater mobile robot has
forward-backward motion with a maximum translational speed of 1.62 knots
(3km/hr.) and 0.54 knots (1km/hr.) for motion in up-down direction. It has a
rotational speed of 1.57 rad/s at the surface of water and 1.3 rad/s under water.
3. Control Module: Control action has been used for moving robot forward-
backward and up-down, turning left- right, adjusting thruster's speed and the
LED's brightness.
4. Visual Sensor (Camera): Pinhole Audio Video Camera (Effective Pixel: PAL:628
x 582, NTSC:510 x 492 , Horizontal Definition: 480 Lines, Focus: Manual
adjustable from 30 mm to Infinity, Horizontal Viewing Angle: 50 Degree,
Camera Range : Audio and video up to 200ft (60m), Voltage: 12V DC, Weight:
50g, Camera Dimensions: 2.0 x 2.0 x 2.5cm) has been used for visual monitoring
at the front part of the robot.
5. Frame with chassis: We have designed and developed chassis with perforated
frame made of thin aluminum sheet for the underwater robot to make it compact
in size, corrosion-free and light in weight. Shape of chassis along with frame is
appropriate for providing required buoyancy.force against robot's weight.
6. Cable Connection: Cable is polyvinyl chloride shielded and negatively buoyant.
The robot is connected to the operator's module through this cable. It provides
power supply to the motors, camera and LEDs. Cable reel with a shaft allows
reeling in or out the cable during operation.
7. Communication with workstation: Moreover the same power cable is also used as
a means of communication with workstation by transmitting operation commands
and video signals.
8. Power Supply: Power supply unit has the short circuit protection. Controller and
power supply unit are integrated in one module.
9. Buoyancy Control. The underwater robot is neutrally buoyant and hydrostatically
stable in the water due to its weight distribution.

EXAMPLE 1
The prototype underwater robot has been tested in realworld underwater environment of
maximum 25m depth. Using upward thrust force, robot can easily move downwards
within water. It has been observed that robot can able to go from surface of water upto
14m depth within water for 51.18 seconds approximately.
EXAMPLE 2
Upward motion of prototype underwater robot within water has also been tested. A
downward thrust can be observed here. Underwater robot requires 61.06 seconds
approximately to rise from 16m depth upto surface level of water.
EXAMPLE 3
A reasonably good speed for linear motion of underwater robot has been achieved by
actuating four horizontal thrusters simultaneously. During forward motion underwater
robot can travel a distance of 460 cm within 5.52 seconds while floating at the surface
level of water.

CLAIMS
We claim
1. The prototype underwater mobile robot operates upto 25m of depth for
underwater monitoring of aqualives.
2. According to claim 1, the chassis of underwater robot is made of thin aluminum
sheet to make it compact in size, light in weight and corrosion-free.
3. According to claim 1, Eight numbers of waterproof motors (45Watts) are installed
for upward-downward, forward-backward and clockwise-anticlockwise motion.
4. According to claim 1, in forward-backward motion, a maximum translational
speed of 1.62 knots (3km/hr.) at water surface level and 1.295 knots (2.4km/hr.)
underwater have been measured for motion in up down direction, maximum

speed of 0.54 knots (1km/hr.) has also been assesed. It has a rotational speed of
1.57 rad/s at the surface of water and 1.3 rad/s under water.
5. According to claim 1, Pinhole Audio Video Camera (Effective Pixel:628 x 582)
has been installed at the front part of the underwater robot along with the LED
lights for visual monitoring of underwater environment and aqua lives.
6. According to claim 1, Power is supplied to the motors, camera and LEDs through
polyvinyl chloride shielded negatively buoyant cable.
7. According to claim 1, Cable connection is made between underwater robot and
workstation for transmitting the control signals and getting the video sensory data.
8. According to claim 1, The prototype underwater robot is neutrally buoyant and
hydrostatically stable due to throughout distribution of its weight symmetrically.