Description:UNDERWATER ROBOT FOR INSPECTION AND SALVAGE

PROBLEM DEFINITION
Underwater search operations are one of the most critical tasks conducted in India; similar to borewell accidents. The different scenarios and objectives of underwater search operations include surface-water rescue, deep-water rescue, recovery of bodies or objects, mapping of underwater terrain or structures, sampling of water or sediments, testing the structural conditions of ships and surveillance of underwater activities or threats. The statistics of waterborne disasters such as floods, cyclones, storms, and other disaster count in India are quite different in numbers. The table. 01 shows the number of disasters, deaths, and affected people for each type of disaster from 2000 to 2019, according to the United Nations Office for Disaster Risk Reduction.
Table. 01 – Disasters in India
Disaster Type No. of Disasters No. of Deaths No. of Affected People
Waterborne 113 26,798 1,509,000,000
Other 208 52,934 1,032,000,000
*(Ref: https://www.indiatoday.in/diu/story/300-disasters-80-000-deaths-100-crore-affected-india-s-two-decade-tryst-with-natural-calamities-1767202-2021-02-08 )
*(Ref: https://www.mapsofindia.com/top-ten/geography/india-flood.html )

The table shows that waterborne disasters accounted for more than one-third of the total disasters and affected more than half of the total population in India. However, other disasters, such as earthquakes, landslides, and heat waves, caused more deaths per disaster than waterborne disasters. But subsequently, waterborne disaster accounts for more than half of the other disasters. This shows there is a high demand for such equipment in India.
The National Disaster Response Force (NDRF) is responsible for such disaster management and to conduct search operations in different types of water bodies - rivers, lakes, seas, and oceans. These regions have varying characteristics and conditions, such as depth, temperature, salinity, turbidity, currents, tides, and waves. Manual rescue operations have many difficulties and risks in performing underwater search operations, such as limited visibility, communication, mobility, and endurance, exposure to hazards such as drowning, hypothermia, decompression sickness, and marine life attacks, and lack of adequate resources, training, and coordination. These factors affect the performance and safety of the rescue team and the victims. Therefore, NDRF team relies on the SONAR system to detect and locate objects or victims underwater, which uses sound waves to measure the distance and direction of the target by measuring the time and angle of the echo. However, the SONAR system has some disadvantages that limit its accuracy and efficiency in underwater search operations, they are
• It generates a lot of noise that can interfere with other acoustic devices.
• It is affected by sound velocity variations over depth, which cause the refraction of acoustic energy and distort the image or signal of the target.
• It is affected by environmental factors such as water temperature, salinity, turbidity, currents, tides, and waves, which can alter the propagation and reflection of sound waves and reduce the range and resolution of the SONAR system.
• It is affected by the shape, size, orientation, material, and movement of the target, which can influence the strength and quality of the echo and make it difficult to distinguish between different types of objects or victims.
• It requires a lot of power and bandwidth to operate and transmit data.

BRIEF DESCRIPTION OF THE DRAWINGS
Figure 01 - Visibility Underwater
Figure 02 - Ultra Short Base Line Technique
Figure 03 - Position overlaid on maps for Navigation
Figure 04 - SONAR Imaging
Figure 05 - Hydrodynamic Design
Figure 06 - Flow Process of the system
Figure 07 - User Interface of the system
Figure 08 - Hydrodynamic Design of Underwater Robot for Inspection and Salvage
Figure 09 - Design of Circuit box for Underwater Robot for Inspection and Salvage
Figure 10 - Threatening Cable attachment
Figure 11 - Dimensional drawing of Underwater Robot for Inspection and Salvage
Figure 12 - Clockwise and Counter Clockwise Propellers
Figure 13 - Propeller hub / Duct with 78 mm height
Figure 14 - Propeller hub / Duct with 58 mm height

IDEA / CONCEPT / SOLUTION TO ADDRESS THE PROBLEM
The concept at the heart of this innovative subaquatic Remotely Operated Vehicle (ROV) system is geared towards facilitating underwater inspections with unprecedented efficiency, safety, and precision. This visionary design encompasses a multitude of advanced features and technologies, each meticulously crafted to address the challenges faced in subaquatic search operations composing of below key features.
(i) Low-Frequency Sensors for Noise Reduction:
The ROV system is equipped with low-frequency sensors to minimize underwater noise generation. This is essential to prevent disturbing marine life and to ensure that the ROV operates covertly and without undue disruption.
(ii) High-Definition Camera for Clear Visibility:
To combat the challenges posed by murky waters as in Figure 01, a high-definition camera (9) is integrated into the system. This camera enhances underwater visibility, providing operators with crisp and detailed images of the submerged environment.
(iii) Ultra-Short Base Line (USBL) Underwater Positioning System:
Figure 02 graphically depicts the Ultra-Short Base Line (USBL) technique to perform the underwater positioning of the drone. This technology ensures accurate tracking and navigation by triangulating the ROV's position relative to a set of transducers deployed on the mother ship.

(iv) Intelligent Navigation and Return to Home Function:
Data analytics, derived from SONAR imaging and the USBL positioning system, empower the ROV with intelligent navigation capabilities. Operators can rely on a "Return to Home" function, which allows the ROV to autonomously return to a predefined location, ensuring a safe and efficient retrieval.
(v) SONAR-Based Relative Position Mapping:
The ROV's operations are further enhanced by utilizing SONAR data and the USBL technique. By employing a set of transducers on the mother ship immersed in the water, the ROV's relative position is accurately detected as depicted in Figure 04. This information is overlaid on maps, providing real-time navigational guidance and precise mapping of the underwater environment. Figure 03 illustrate the model of relative position map. A separate webpage is designed for the visualizing the real time data for sonar images USBL position and camera feed as shown in Figure 7.
(vi) Hydrodynamic Design for Reduced Drag:
Figure 05 reveals the optimized hydrodynamic design (1) of the ROV. The design is optimized by effectively reducing drag and allowing for swift, efficient movement through water. This feature ensures that the ROV can manoeuvre smoothly and rapidly, responding promptly to mission demands.
(vii) Six-Degrees of Freedom (DOF) Manoeuvrability:
The ROV boasts an impressive Six-Degrees of Freedom (DOF) manoeuvrability. This level of freedom allows for agile movement in all directions, including forward and backward, up and down (heave, sway and surge), and rotation along three axes (roll, pitch and yaw). Such flexibility enables the ROV to navigate through complex underwater terrains with precision. These six degrees of freedom is achieved by optimized arrangement of six BLDC motors with two different performance levels. The motors are placed on the axis of the propeller ducts (either (3) or (4)) to provide more thrust force. Each motor is covered with the custom propeller of two different thrust directions ((5) and (6)) for the proper angular momentum balancing.
(viii) Temperature and Pressure Sensors:
To address the challenges posed by varying sound velocity in underwater environments, temperature and pressure sensors are integrated into the system in the circuit box (2). These sensors provide essential data for accurate sound velocity corrections, enhancing the precision of distance measurements. The proposed subaquatic ROV system is a comprehensive solution to the challenges encountered in underwater inspections. By combining cutting-edge technologies, intelligent navigation, and high-quality sensors, it empowers the underwater inspection teams to conduct missions with unprecedented effectiveness, safety, and precision. This innovative system not only mitigates the challenges but also sets a new standard for underwater operations, emphasizing the importance of minimal noise disturbance, clear visibility, and precise positioning.

PROJECT DESCRIPTION AND HIGH-LEVEL DESIGN
• Hydrodynamic Design by Biomimicking:
The core innovation of this ROV prototype lies in its hydrodynamic design (1), which draws inspiration from the biomechanics of sea turtles. This design emulates the streamlined shape and efficient swimming patterns of these marine creatures. The design is composed with precisely calculated dimensions (as shown in Figure 11), to accommodate the electronics as well as for the manoeuvrability of the drone. The ROV is of an altered ellipsoid structure to reduce the hydrodynamic drag coefficient of the drone.
By doing so, the ROV can navigate underwater with improved efficiency, reduced resistance, and enhanced manoeuvrability. The key features of the hydrodynamic design include a smooth, low-drag body shape, fin-like extensions for stability and control, and specialized contours for minimizing water turbulence. This bio-mimicked design is a testament to the ingenuity of adapting nature's solutions for engineering challenges.
• Kevlar Material for Structural Integrity:
The structural body (1) of the ROV is constructed from Kevlar, a lightweight yet exceptionally strong synthetic fiber. Kevlar is renowned for its durability and ability to withstand high pressures, making it an ideal choice for subaquatic operations. By utilizing Kevlar, the ROV can safely operate at depths of up to 150 meters, offering a wide operational range while maintaining structural integrity under varying hydrostatic pressures.
• Low-Frequency Ultrasonic Sensors for Noise Reduction:
One of the pivotal aspects of the ROV's sensor array is the integration of low-frequency ultrasonic sensors. This choice is deliberate, as low-frequency sensors are known for producing significantly less noise compared to their high-frequency counterparts. This not only prevents undue disturbance to marine life but also ensures that the ROV operates discreetly and without causing unintended disruption to the underwater environment. The preference for low-frequency sensors aligns with the goal of minimizing the impact on the ecosystem.
• High-Definition Camera with High Lumens Flash:
To enhance the ROV's underwater visibility, a high-definition camera (9) with a high lumens flash is integrated into the system. This camera is designed to capture clear, detailed images and videos in challenging underwater conditions, including low light or murky waters. The high lumens flash provides powerful illumination, enabling operators to observe and document the submerged environment with exceptional clarity. This feature is crucial for mission success and data collection in less-than-ideal visibility conditions. Also, a pair of LASERs (8) were incorporated alongside the camera so that the dust particles are absorbed by the LASER light providing the camera a better view.
• SONAR Sensors for Precise Underwater Positioning:
The ROV employs a set of SONAR sensors for its underwater positioning system. These sensors play a critical role in the ROV's ability to navigate and map its surroundings accurately. By utilizing SONAR technology, the ROV can generate a detailed understanding of the underwater terrain, including obstacles and features. The data collected by these sensors is then used to overlay the ROV's precise position on navigational maps, providing real-time guidance for operators. This advanced navigational capability ensures that the ROV can operate with precision, even in complex underwater environments. Due to its stability various end effectors can be attached with the ROV for the particular requirements, such as sample collection, Corrosion testing of ships, small object gripping, etc. One of such end effecters was now attached with the ROV as (7) which was driven by a servo motor. The entire system was driven by wired mode in which the power signals were transmitted through the (10) threatening cable connecter.

PROJECT BENEFITS
? Enhanced Safety and Timely Response:
The project significantly enhances safety by facilitating deep-water rescue operations with the subaquatic ROV. Its ability to navigate challenging underwater terrains and perform precise, real-time investigations allows for a quicker and more efficient response to emergencies. Lives can be saved in a timely manner, reducing the risk of further harm or loss.
? Effective Fatal Victim Recovery:
One of the critical benefits of this project is its capability to conduct underwater inspections and search for fatal victims. The ROV's advanced sensory and imaging technology aids in locating and recovering victims with a high degree of precision. This not only provides closure to families but also supports the forensic investigation process.
? Efficient Use of Resources:
The project optimizes resource utilization by reducing the time and manpower required for underwater missions. The ROV's ability to perform deep-water rescue and investigation, along with SONAR imaging, minimizes the need for divers in dangerous conditions.
? Data-Driven Decision Making:
Underwater SONAR imaging is a game-changer in this project. It provides detailed insights into underwater terrains, helping operators make informed decisions. Whether for search and rescue or forensic investigations, the precise data collected ensures that actions are based on real-time information, increasing the likelihood of mission success.
? Minimal Environmental Disruption:
The ROV's low-frequency sensors, hydrodynamic design, and discreet operation with low noise levels reduce environmental disruption. This benefits marine ecosystems by minimizing disturbances during operations. Preserving underwater ecosystems aligns with ecological responsibility and ensures a sustainable approach to underwater missions.

? Versatility and Adaptability:
The project's multifaceted approach caters to a range of missions, including deep-water rescue, investigations, and inspections. Its adaptability is a significant advantage, as it can be deployed across various underwater environments, from lakes and rivers to oceans, ensuring that the ROV prepared for a wide spectrum of scenarios.
? Clear Underwater Visibility:
The high-definition camera and high lumens flash ensure clear visibility in murky waters. This feature is invaluable for search and rescue missions and underwater investigations. It aids in locating victims, evidence, or obstacles, allowing operators to work with precision in conditions where traditional visibility is limited.
? Improved Navigation and Mapping:
The project's underwater positioning system with SONAR imaging enhances navigation and mapping. Real-time overlay of the ROV's position on navigational maps provides operators with a comprehensive understanding of the underwater environment. This capability is instrumental in avoiding obstacles, navigating complex terrains, and ensuring mission success.
? Structural Durability and Depth Capability:
The ROV's Kevlar body construction ensures structural integrity at depths of up to 100 meters. This depth capability is crucial for responding to emergencies in deeper waters, where conventional methods may be limited. The ROV's ability to withstand higher pressures expands the scope of missions.
POTENTIAL APPLICATIONS
Apart from NDRF-rescue applications the ROV is also suitable for the applications like Water sample collection, object finding, pearl hunting, corrosion testing for ships, leakage inspection and structural life testing of underwater pipes, etc. The ROV design is also capable of carrying the external detachable payloads like grippers, sample collectors, testing tools as shown in Figure 11 for the particular inspection purposes to carry out the above-mentioned tasks.
, Claims:We Claim:
Claim 1: An underwater rover that composed of the hydrodynamic design (1), Camera module (9), Motor Stability Controller (2), LASERs (8), Grippers (7), Clockwise (5) and contraclockwise propellers (6), Propeller Duct/Hub to produce thrust ((3) and (4)) and Threatening Cable connecter (10), which capable of attaining six degrees of freedom with 2m/s average speed.
Claim 2: The rover mentioned in the Claim 1 has the optimized ellipsoid hydrodynamic structure with hermetically impermeable body.
Claim 3: The robot depicted used in Claim 1 uses the USBL technique for positioning.
Claim 4: The underwater robot in Claim 1 uses SONAR imaging and image processing to identify objects and victims.
Claim 5: The underwater rover in Claim 1 has various detachable end effectors.