Autonomous Underwater Vechicle by deepak and aatmaj
- 1. AUTONOMOUS UNDERWATER VEHICLES BAVGE DEEPAK RAJKUMAR NA22B031 AATMAJ KAUSHIK BHAYANI NA22B018
- 2. INTRODUCTION TO AUVS Autonomous Underwater Vehicles (AUVs) are unmanned, self-propelled vehicles designed to operate underwater without real-time human control. Perform missions such as data collection, mapping, and inspection autonomously. Pre-programmed missions, onboard sensors, decision- making algorithms.
- 3. AUVS VS ROVS Autonomous Underwater Vehicles (AUVs) • Operate independently based on pre-set instructions. • Do not require a tether; communicate via onboard systems. • Typically used for long-duration missions. Remotely Operated Vehicles (ROVs) • Controlled in real-time by operators on a surface vessel via a tether. • Require constant human supervision. • Often used for tasks requiring precision and real-time decision-making, such as maintenance or repair.
- 4. AUVs are built using corrosion-resistant materials like titanium, aluminum alloys, and lightweight carbon fiber composites for strength and buoyancy control. MATERIAL Sealing techniques for waterproofing sensors and electronics in AUVs include O-rings for mechanical seals, potting with waterproof resins, and pressure-rated housings to protect components from water ingress at various depths. SEALING TECHNIQUES CFD simulations optimize AUV design by minimizing drag and improving efficiency through refined hull shapes and smoother surfaces. HYDRODYNAMICS AUV propulsion systems use thrusters for movement and control surfaces for steering, with vectoring thrusters enabling precise control over pitch, roll, and yaw for full maneuverability. PROPULSION SYSTEM MECHANICAL DESIGN ASPECTS OF AUVS
- 5. PROPULSION SYSTEMS Presentations are communication tools that can be used as lectures, speeches, reports, and more. MULTIPLE THRUSTER GLIDER SINGLE THRUSTER • A single propeller combined with control surfaces such as rudders and fins. • The thrust from the propeller results in linear movement along the AUVs axis. • Directional yaw control is achieved by adjusting the angle of these control surfaces. • Ballast systems are used for controlling the heave motion and maintaining a consistent depth. • Multiple thrusters offer control by independently managing different degrees of motion. • Fore and aft thrusters handle forward/reverse movement, lateral thrusters enable side-to-side motion, and vertical thrusters control depth and pitch. • The AUV can maneuver in six degrees of freedom. • This configuration provides high maneuverability, making it ideal for tasks like underwater inspections and close-proximity operations. • Glider-type AUVs use buoyancy control instead of traditional thrusters for propulsion. • These AUVs adjust their buoyancy to move up or down through the water column by changing their internal ballast system. • As the glider sinks or rises, its wings generate lift, allowing it to move forward in a slow, gliding motion.
- 6. CONTROL AND COMMUNICATION ASPECTS OF AUV Choice of sensors is also essential so that the AUV is able to gain information of its surroundings. SENSORS The algorithms are the main blocks which will determine how your AUV manevers. ALGORITHMS Inner circuitry of the AUV which includes choice of microcomputers, microcontrollers and their seamless connection with sensors CIRCUIT DESIGN
- 7. Depth Sensor: Measures the water pressure to determine the depth of a submerged object, using the relationship between pressure and depth. IMU (Inertial Measurement Unit): Combines accelerometers and gyroscopes to track the object's acceleration and angular velocity, providing data on its position and orientation in space. DVL (Doppler Velocity Log): Uses the Doppler effect of sound waves reflected off the seafloor to calculate the velocity and direction of an underwater vehicle. Underwater GPS: Utilizes acoustic signals transmitted between surface buoys and submerged devices to triangulate positions underwater, similar to traditional GPS but adapted for water. Acoustic Modem: Converts digital data into acoustic signals for transmission underwater, enabling communication between devices using sound waves. SENSORS
- 8. INERTIAL MEASUREMENT UNIT (IMU) It typically consists of three primary components: GYROSCOPES MAGNETOMETER ACCELEROMETRER Working principle: Based on Newton's second law (F = ma), microscopic structures bend due to acceleration forces, and changes in their position are measured to derive acceleration. Working principle: Utilizes the Coriolis effect, where vibrating components detect angular velocity by experiencing a force proportional to rotational speed. • Measures angular velocity (rotation) around X, Y, and Z axes (roll, pitch, yaw). • Tracks changes in orientation over time. • Measures linear acceleration along X, Y, and Z axes. • Detects tilt and orientation relative to gravity. • Measures the magnetic field strength and direction (compass heading). • Corrects drift in gyroscope data and provides absolute orientation. Working principle: Uses the Hall Effect or magnetoresistance to sense magnetic fields and calculate heading relative to Earth's magnetic field.
- 9. ACOUSTIC MODEM DOPPLER VELOCITY LOGGER A DVL works by using the Doppler effect, which is the change in frequency of a wave due to the relative motion between the source of the wave and the observer. DVLs transmit a series of sound waves towards the sea bottom and then measure the frequency shift of the reflected echoes. The Doppler shift is directly proportional to the relative velocity between the vehicle and sea bottom. Typically, a DVL has 4 transducers which emit sound beams in 4 different directions, by comparing the Doppler shift echoes from each transducer, the DVL can calculate the vehicle’s speed and direction of travel. It enables data transmission underwater using sound waves, as radio waves (used in traditional wireless communication) are highly attenuated in water. Here's how it works: Working Principles: • The modem takes digital data and converts it into an analog signal. • This analog signal is modulated into sound waves (acoustic signals) suitable for underwater transmission. • The modem uses a transducer to generate acoustic signals in the form of pressure waves in the water. These sound waves propagate through the water over long distances (depending on water conditions and frequency used).
- 10. SLAM ALGORITHM Key Components of SLAM: 1.Localization: This is typically done using various sensors that provide information about the surroundings. It can be achieved through techniques such as filtering (e.g., Kalman filters, particle filters) to fuse sensor data and estimate the robot's pose (position and orientation). 2.Mapping: The creation of a map that represents the environment. This could be a 2D grid map, a 3D point cloud, or a topological representation. The map is built by collecting data from the sensors as the robot explores the environment, identifying features or landmarks that can be used for both navigation and reference. How SLAM Works: 3.Sensor Data Collection: The robot moves through the environment, collecting data from its sensors 4.Feature Extraction: Key features or landmarks in the environment are detected from the sensor data. These features can be points, edges, or more complex structures. 5.State Estimation: Using the collected data, the robot estimates its current position and orientation, often employing algorithms like the Extended Kalman Filter (EKF) or particle filters to account for uncertainty and noise. 6.Map Update:As new data is gathered, the map is continuously updated to reflect the robot's exploration and the features identified. 7.Loop Closure: When the robot revisits a previously mapped area, it recognizes landmarks and corrects any drift in the localization, refining both the map and the estimated trajectory. This process is critical for ensuring accuracy over time.nown environments, such as disaster sites or underwater areas, while mapping and localizing simultaneously.
- 11. KALMAN FILTERS In general, the state at time xt is generated stochastically. Thus, it makes sense to specify the probability distribution from which xt is generated. The Kalman filter is a mathematical algorithm used for estimating the state of a dynamic system from a series of noisy measurements. Multivariate Gaussian Distribution Kalman filters represent the belief bel(xt) at time t by the mean µt and the covariance Σt. The input of the Kalman f ilter is the belief at time t 1, represented by µt 1 and Σt 1. To update these parameters, − − − Kalman filters require the control ut and the measurement zt. The output is the belief at time t, represented by µt and Σt Advance filters like EKF etc can be developed further................
- 12. Control algorithms are essential for the effective operation of Autonomous Underwater Vehicles (AUVs), allowing them to maintain stability, navigate, and perform tasks autonomously. Here’s a detailed look at various control algorithms commonly used in AUVs, their principles, and applications: CONTROL ALGORITHM Description: A widely used feedback control algorithm that calculates an error value as the difference between a desired setpoint and a measured process variable. It then applies a correction based on proportional, integral, and derivative terms. ⚬ Proportional (P): Produces an output value that is proportional to the current error value. ⚬ Integral (I): Integrates the error over time, addressing accumulated past errors. ⚬ Derivative (D): Predicts future error based on its rate of change. • Applications: Used for maintaining depth, heading, and speed of the AUV. Adjusts control surfaces or thrusters to minimize deviation from desired states. PID Control (Proportional-Integral-Derivative) Components
- 13. AUVS have a wide range of applications in the industrial field due to their ability to operate in challenging underwater environments. 1. Oil and gas exploration - AUVs are used for seafloor mapping, pipeline inspection and monitoring offshore oil rigs They can inspect underwater infrastructure for cracks or leaks without human intervention. 2. Telecommunication cables - AUVs are involved in inspecting and maintaining the vast network of submarine telecommunication cables. 3. Environmental monitoring - AUVs are deployed to monitor water quality, pollution levels, and the impact of industrial activities on marine ecosystems. They collect different data like temperature salinity etc Applications of AUVs
- 14. Industrial AUVs It has a mission endurance of nearly 70 hours with speeds up to 5 knots at depths up to 600 meters. With its increased payload it has a range of 286 nautical miles. • Very stable and low noise hydrodynamic platform for payload sensors • High maneuverability providing terrain following and turning radius of 15 meters • Operating depths of 3000, 4500, and 6000 meters REMUS600 HUGIN AUV
- 15. REFERENCES TEXTBOOKS 1.Probabilistic robotics - THRUN, BURGARD and FOX LINKS 1.REMUS AUV - https://www2.whoi.edu/site/osl/vehicles/remus-600/ 2. HUGIN AUV - https://www.kongsberg.com/discovery/autonomous-and-uncrewed-solutions/auv/hugin/ 3. https://www.youngwonks.com/blog/What-is-a-Gyroscope-and-How-Does-It-Work 4.https://en.wikipedia.org/wiki/Inertial_measurement_unit 5.https://waterlinked.com/dvl 1.Springer Handbook of Ocean Engineering - Dhanak and Xiros
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