Coastal Water Profiler Hover Control for Seabed Altitude Tracking
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Solution Overview
Problem
Existing profilers for coastal waters lack altitude control, leading to overshooting of desired depths, inability to hover, slow sensor response times, and limited dynamic mission changes, which restrict their ability to effectively track water column properties and seabed topography.
Innovation Solution
Incorporating an altitude and hover control system using acoustic modems and a Linear Quadratic Regulator (LQR) controller, combined with a complementary filter, to maintain a constant altitude above the seabed and adjust depth, along with additional features like a digital camera and echo-sounder for enhanced data collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a profiler uses buoyancy pumps or free-falling gravity types to measure vertical structure, then it can operate in coastal waters, but it cannot maintain precise altitude control or hover at desired depths
Solution Approach 1:
The patent implements a feedback control system using an echo-sounder to continuously measure the distance between the profiler and the seabed. The microcontroller processes this feedback signal and adjusts the thruster output accordingly to maintain the desired altitude above the seabed, resolving the contradiction between measurement precision and operational capability.
Solution Approach 2:
The patent replaces traditional mechanical depth control mechanisms (buoyancy pumps, drop weights) with an acoustic-based control system. The echo-sounder uses acoustic waves to measure depth, and the microcontroller dynamically adjusts thruster propulsion to achieve precise altitude control, eliminating the need for complex mechanical depth positioning systems.
2Productivity
If a profiler moves continuously to collect data, then it covers more area, but sensor response time is insufficient to accurately sample water layer properties
Solution Approach 1:
The patent implements periodic hovering behavior where the profiler alternates between moving to new locations and pausing at discrete depths. During hover phases, the profiler remains stationary for sufficient time to allow slow-response sensors to accurately measure water layer properties, while maintaining overall productivity through systematic coverage patterns.
3Speed
If a profiler uses a thruster for depth control, then it can reach programmed depths, but it overshoots the desired depth due to momentum and low moment of inertia
Solution Approach 1:
The patent uses real-time feedback from the echo-sounder to monitor the profiler's distance from the seabed and dynamically adjusts thruster output. The microcontroller processes the feedback signal and modulates thruster power to prevent overshooting, maintaining both speed and precision by reducing thrust as the target altitude is approached.
Solution Approach 2:
The patent applies preliminary anti-action by reducing thruster power before the profiler reaches the target altitude. The control system anticipates the approach to the desired depth and preemptively reduces thrust to counteract the momentum that would cause overshooting, ensuring accurate depth positioning.
4Weight of moving object
If a profiler is designed for routine profiling work in shallow coastal waters, then it should be lightweight and compact, but existing devices like ASIP require special purpose ships with winch systems
Solution Approach 1:
The patent replaces heavy mechanical deployment systems (winches, A-frames) with an acoustic-based depth control system. The echo-sounder provides real-time feedback on distance from the seabed, enabling the lightweight profiler to self-regulate its depth and hover capability without requiring complex mechanical deployment infrastructure.
Solution Approach 2:
The patent enables the profiler to be self-sufficient in depth control through onboard acoustic sensing and processing. The microcontroller autonomously processes echo-sounder feedback signals and adjusts thruster output without external intervention, allowing deployment from simple platforms rather than requiring specialized ships with winch systems.
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
Enables precise altitude control above the seabed, allows for stationary data collection, reduces sensor response time errors, and facilitates dynamic mission changes, enhancing the profiler's capability to track phytoplankton interactions and seabed topography.
Implementation Method 1
an echo-sounder mounted on one of rear fins and used to measure surface wave profiles in hover mode
Implementation Method 2
an acoustic modem mounted on another rear fin and used to communicate with a profiler from a surface craft
Implementation Method 3
a thruster whose thrust neutralizes upwardly directed buoyant force so as to achieve altitude control
Implementation Method 4
a depth sensor mounted on the nose cone of the profiler
Data Source
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AI summary
The present invention relates to an altitude Controlled Profiler for Coastal waters is a versatile altitude controller that maintains the device at a fixed altitude above the seabed. With a small modification in the control logic the same device can be made to hover below the sea surface. Altitude control will enable properties of the water column to be tracked at discrete depths. The invention opens up a host of new applications in seabed photography, terrain profiling of the seabed, and time tracking of surface phytoplankton blooms.