TITLE OF THE INVENTION
A low cost Autonomous Underwater Vehicle having five degrees of freedom and minimum of two thrusters.
BACKGROUND OF THE INVENTION
Underwater Vehicle (UV) travels underwater with or without input from an operator/pilot. Underwater Vehicles (UVs) have the potential to revolutionize our access to the oceans to address critical problems such as underwater search and mapping, climate change assessment, marine habitat monitoring, and shallow water mine countermeasures. They can measure physical characteristics of water such as temperature, salinity, dissolved oxygen and can detect chlorophyll from microscopic marine algae. It can measure concentrations of small particles in water, map the seafloor, and collect the images of the seafloor and the mid water. They have the potential to become ubiquitous tool for ocean exploration and sampling. Underwater vehicles are grouped into two main categories - (i) Manned Underwater Vehicles (MUVs) and (ii) Unmanned Underwater Vehicles (UUVs). While MUVs are able to operate underwater with a human occupant (such as submarine), UUVs are able to operate without a human occupant.
The use of remotely operated underwater vehicles is widespread, and their tasking are going more complex in deeper waters, there is a need to free the vehicle from the power and signal tether to increase (i) the level of control autonomy and (ii) the manoeuvring precision of these underwater robots. These needs are fulfilled by the development of Autonomous Underwater Vehicles (AUVs). This level of control achieved in AUVs, under most environmental conditions, permits the vehicle to follow precise pre programmed trajectories wherever and whenever required. AUVs are increasingly becoming viable for commercial ventures such as seabed surveys, oceanographic data collection, and offshore oil and gas operations.
The generic design of an AUV consists of a propeller thruster combined with control fins to propel and steer the vehicle. In order to achieve an AUV with Remotely Operated Underwater Vehicle (ROV) capabilities, a propulsion method that provides thrust at low velocities is needed, as well as a sensing system that works efficiently in

cluttered environments. For high efficiency, these sensing and actuation technologies need to be well integrated with the typical manoeuvres the vehicle needs to make. Manoeuvring control forces are generated by fluid flow over control surfaces, and the torpedo- shaped body is optimized for low drag during forward motion. These vehicles also use powerful SONARs to sense their surroundings. At cruising speeds, and for relatively uncluttered spaces, this combination of mechanical design and long-range sensing is extremely efficient and effective.
Programming is done for vehicle to stop thrusting and float passively at a specific depth or density layer in the sea, or to actively loiter near a desired location. AUVs may also be programmed to swim at a constant pressure or altitude or to vary their depth and/or heading as they move through the water, so that undulating sea-saw survey patterns covering both vertical and/or horizontal swaths may be formed. They also provide a highly productive means of performing seafloor surveys using acoustic or optical imaging systems. AUVs are programmed at the surface and then navigate through the water their own, collection data as they go. For the data gathered by an AUV to be of value, the location from which the data has been acquired must be accurately known.
INVENTION SUMMARY
This is a low cost Autonomous Underwater Vehicle (AUV) with 2 thrusters, 4 buoyant and a robotic arm, which can go underwater to places human cannot reach and pick samples from deep sea for research, navy, ocean surveillance and other purposes.
DETAILED DESCRIPTIONS OF INVENTION
This is a unique idea of a low cost Autonomous Underwater Vehicle (AUV) with 2 thrusters, 4 buoys and a robotic arm, which can go underwater to places human cannot reach and pick samples from deep sea for research, navy, surveillance and other purposes.
The design emphasis on the use of two thrusters reduce the cost of the vehicle and along with the use of two thrusters provides five degrees of freedom to AUV. The vehicle uses two cameras one at front and one at bottom for underwater imaging and also

processes those images to avoid obstacles to transverse it desired path and also picking samples using the robotic arm. The vehicle uses sensors which are IMU (Inertial Measurement Unit), temperature sensor, pressure sensor and flow meter controlled by 2 Arduinos in serial communication with each other. The whole system is controlled by an onboard motherboard. The motherboard continuously processes the image from the cameras and command the Arduino to move the vehicle accordingly. The pressure sensor is used for depth measurement and FMU is used for maintaining the stability of the vehicle. Flow meter measures the velocity of the vehicle and hence distance is calculated to avoid any obstacle. The buoys are used for heave motion and rolling, whereas for pitching, traverse mass mechanism is employed and thrusters are for surge and yawing motion.
DESCRIPTION OF DRAWINGS
Figure 1: Top and Bottom View of AUV
Figure 1 shows the top and bottom view of the AUV. This figure indicate the relative arrangement of the thrusters and the buoyants and also the cameras, electronic circuit, traverse mass can be seen. The thrusters are mounted at the sway axis of the AUV which passes through the centre of gravity. If the thrusters are mounted up or below the sway axis, a moment will act on the AUV which will cause the unnecessary pitching. Also to maintain the balancing, the buoyants are mounted symmetrically.

Figure 2: Isometric View of AUV
In the figure 2, which represents the isometric view of the AUV, shows the flange, one of the thruster, dome, buoys and the electronics circuit tray. A large number of holes for nut and bolts are provided in the flange for the proper waterproofing of the AUV.
Figure 3: Front and rear view of AUV
Figure 3 represents the front and rear view of the AUV, here in this figure the position of the gripper can be observed and also that of frame. This view also represents the symmetricity of AUV as the components are arranged in such a fashion that no any disbalancing came into existence because of the mass distribution i.e. the vehicle is hydrostatically stable.

CLAIMS
Claim 1: AUV Structure
• The AUV is provided with a leak proof pressure hull of cylindrical shape stainless-steel cage to provide the strength at high pressure environment. The stainless-steel cage structure surrounding the hull facilitates various components like two thrusters at the port and starboard sides of the vehicle, four buoys at each corner of the top face, a robotic gripper, two cameras, a sample collector and a traverse mass mechanism are also attached to the AUV. The degree of freedom of the vehicle is five i.e. Surge, Heave, Pitching, Rolling and Yawing.
• The AUV of claim 1 above also consist of three perforated aluminium plates to attach various electronic components that are not allowed to come in direct contact with any liquid. Leak-proofing is done with the aid of the O-rings, gaskets and leak-proof threaded fittings.
• The AUV of the claim 1, comprises of two cameras with LED light to perform effectively in the low light environment. Cameras help in navigation of the vehicle through image processing.
• The AUV of the claim 1, further comprising the two Arduino with serial communication between them and also comprising of the pressure sensor, temperature sensor, IMU sensor, flowmeter for the safety and the controlling of the vehicle.
Claim 2: AUV Functioning and other System
• The AUV of the claim 4, provided with the inward and outward linear motion of the perforated plates.
• The method of claim 5, further comprising the circular disc which is joined with the perforated plates to allow the sliding inward and outward motion of these plates and also helps in leak proofing of the vehicle.
• The AUV buoyancy system consists of four buoys to control the buoyancy of the vehicle. The buoy includes a threaded shaft on which a piston slides in clockwise and counter clockwise manner. The piston is housed in a cylindrical

system, by the upward and downward motion of the piston the buoyancy of the vehicle altered.
• The AUV of above claims further comprises of a stepper motor as actuator for the accurate motion for the piston by rotating the threaded shaft.
• The AUV of above claims further comprises of a robotic arm and a sample collector bore to grasp the solid objects and to collect the liquid samples.
• The AUV of above claims further comprises of the two high grade cameras so that the proper investigation of the marine environment as well as motion control using feedback mechanism can be achieved.
• The AUV of above claims, further comprises of a traverse mass mechanism to control the pitching of the vehicle i.e. if the vehicle needs to be tilt at some angle about the sway axis, with the help of this mechanism the vehicle can be tilted at the required angle.
• The AUV of above claims, further comprises of a shaft on which the battery tray attached, acts as the dead weight slides in the fore and aft direction. The displacement to be made by the battery tray is predetermined for various angles. The centre of gravity of the vehicle is slightly downward towards the base of the vehicle and at the centre in the fore and aft direction and port-starboard direction when the vehicle is in equilibrium. The position of centre of gravity of the vehicle gets altered as the battery tray of traverse mass displaces.
• The AUV of preceding claims, wherein the orientation of the thrusters is not fixed and hence the thrust force generated by them can be altered by altering the orientation of the thrusters.
• The propulsion system of the AUV comprises of two thrusters attached at the port and starboard side of the vehicle. These thrusters can rotate about the sway axis of the vehicle so that the thrust can be obtained in all directions along the vertical plane. Thrusters are mounted on servo-motor to facilitate the rotary motion to the thrusters. Thrusters are also supported with a mechanism so that the vertical pressure load does not act on the axis of the shaft and hence work load of servo motors are minimized and the performance of these servos are enhanced.

Claim 3: AUV Movement
• The AUV of preceding claims, wherein the degree of freedom of the vehicle is five i.e. Surge, Heave, Pitching, Rolling and Yawing.
• The AUV of Claim 15, wherein the Surge (fore and aft motion) of the vehicle is obtained by the thrust force generated by the thrusters attached at the port and starboard side of the vehicle and keeping them in the straight position. The thrust force generated by the thrusters during this motion is in the fore and aft direction. The direction of the vehicle is reversed by reversing the direction of the thrust force keeping the thrusters at the same position.
• The AUV of above claims, wherein the Heave (Upward-downward motion) of the vehicle is obtained with the help of the buoys by changing the buoyancy of the vehicle and with the help of the thrusters too.
• The method of claim 15, wherein the heave motion achieved by making the AUV negatively and positively buoyant for downward and upward motion respectively using the four buoys. For the slow heave motion only the buoys are used but when the rapid upward or downward motion is mandatory, the position of the thrusters is arranged in such a manner so that the thrust force generated by the thrusters is in the upward and downward direction depending on the type of motion required.
• The method of claim 15, wherein the pitching of the vehicle is controlled with the help of the traverse mass mechanism and if necessary in some case, the buoys can also be used and the rolling of the vehicle is obtained with the help of the buoys by changing the buoyancy on any of the port or starboard side of the vehicle.
• The method of claim 15, wherein the yawing of the vehicle is obtained by the differential force of the thrusters keeping the orientation of the thrusters fixed. The thrust force of any one of the thrusters is changed with respect to the other and hence a differential force is obtained to get yawing motion.