AUV Attitude Stabilization for Underwater Laser Link Pointing
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Solution Overview
Problem
Current underwater remote operating vehicles (ROVs) face challenges with tethered connections that can twist, tangle, or fail under extreme pressure, limiting their ability to efficiently search and monitor large seabed areas, and autonomous underwater vehicles (AUVs) lack effective wireless communication, making deep sea exploration inefficient.
Innovation Solution
The design of a swarm of AUVs equipped with high-speed laser communication modules and advanced attitude control systems, including a Double Gimbal Control Moment Gyro (DGCMG) and reaction mass systems, enables wireless high-speed data communication and agile, accurate beam steering for optical data transmission, allowing vehicles to maintain communication and control without tethers, even in the presence of ocean currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tethered ROVs are used to search and monitor large seabed areas, then real-time control and communication are possible, but the connecting cable can twist, tangle, or become compromised under extreme pressure, posing serious risks and limiting operational efficiency
Solution Approach 1:
The patent removes the tether cable from the ROV system, transitioning from tethered to autonomous operation. The ROV operates independently without physical connection to the surface vessel, eliminating cable-related failures while maintaining real-time control through wireless communication systems.
Solution Approach 2:
The mechanical cable connection is replaced with wireless communication systems (acoustic modems, satellite communication, or electromagnetic waves). This substitution eliminates the physical constraints and failure modes of mechanical tethers while enabling data transmission and control commands between the surface vessel and autonomous vehicles.
2Area of stationary object
If multiple tethered ROVs are deployed to cover large areas, then comprehensive monitoring is achieved, but the cables can tangle with each other and require complex coordination, increasing system complexity and reducing ease of operation
Solution Approach 1:
The system divides the monitoring task into independent segments, with each ROV operating autonomously in its designated zone. Each vehicle makes independent decisions about navigation, data collection, and obstacle avoidance, eliminating the need for complex real-time coordination between multiple tethered vehicles while achieving comprehensive area coverage.
Solution Approach 2:
Each ROV is equipped with autonomous navigation and decision-making capabilities, allowing it to independently manage its own operations including obstacle avoidance, path planning, and data transmission scheduling. This self-service capability eliminates the need for complex external coordination mechanisms.
3Stability of the object's composition
If conventional ROV systems use thruster activations to counter external disturbances and maintain position, then position stability is achieved, but the response is relatively slow as it requires accelerating and pushing water around the vehicle body
Solution Approach 1:
The reaction mass system uses periodic ejection of water or gas in controlled pulses to generate corrective forces. By ejecting fluid in rapid periodic cycles, the system achieves both fast response to disturbances and stable position maintenance, overcoming the slow response limitation of continuous thruster operation.
Solution Approach 2:
The system employs hydraulic or pneumatic reaction masses that eject water or gas to generate rapid corrective forces. This approach uses the compressibility and flow characteristics of fluids to achieve faster response times compared to mechanical thrusters, while maintaining position stability through controlled ejection cycles.
4Ease of operation
If AUVs use thrusters for reorientation maneuvers, then positioning and orientation control is achieved, but a substantial amount of power is consumed to pump bulk fluid, reducing operational time
Solution Approach 1:
The reaction mass system uses periodic, pulsed ejection of fluid rather than continuous thruster operation. By ejecting water or gas in controlled intervals only when maneuvering is required, the system achieves necessary positioning and orientation control while dramatically reducing overall power consumption compared to continuous bulk fluid pumping.
Solution Approach 2:
The system discards small amounts of water or gas from onboard reservoirs to generate maneuvering forces. This approach trades minimal consumable resources for maneuvering capability, avoiding the high energy costs of continuous thruster operation while maintaining control authority.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables efficient and accurate underwater communication and control, allowing for real-time data transmission and vehicle coordination, reducing power consumption and operational time while minimizing the impact of external disturbances, thus enhancing the exploration and monitoring capabilities of AUVs.
Implementation Method 1
an active attitude stabilization system centered in the interior core of the body configured to rotate the body of the vehicle with respect to the center of the body
Implementation Method 2
a reaction mass inertial system disposed in the interior core of the body, the system configured to control and stabilize linear position of the vehicle
Implementation Method 3
high-speed laser communication modules and advanced attitude control systems, including a Double Gimbal Control Moment Gyro (DGCMG) and reaction mass systems, enables wireless high-speed data communication
Data Source
AI summary
Autonomous underwater vehicles and systems are provided with fast stabilization and fine attitude control with a constant and high rotational speed flying wheel to rotate the vehicle's body with respect to its core and optionally a combination of reaction masses used in three perpendicular axes. The gimbal and the reaction mass inertial systems are used for fast response to any angular or linear disturbance coming from the ocean current or waves. When equipped for optical communications, the vehicle has an optical receiver and transmitter and controller that provides three levels of attitude stabilization: gimbal and the reaction mass inertial systems; isolated movable platform and fine optical beam steering for targeting the laser beam from the transmitter. The ability to maintain precise positioning allows multiple vehicles to be optically linked.