Inertial Navigation for Scuba Diving Using Accelerometer and Magnetometer
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Solution Overview
Problem
Current underwater navigation methods face challenges such as limited visibility, concurrent task management, equipment limitations, and safety concerns, particularly with ultrasound-based systems that rely on line-of-sight and are affected by seawater properties, leading to reduced reliability and accuracy.
Innovation Solution
A system using inertial sensors, including accelerometers and magnetometers, to calculate propulsion power and velocity by recognizing swimming kick types and compensating for sea currents, providing accurate navigation information through a user device integrated with scuba diving equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasound-based navigation systems are used, then direction and distance calculations can be performed, but reliability is compromised due to seawater properties affecting sound propagation
Solution Approach 1:
The patent replaces the ultrasound-based acoustic navigation system with an inertial navigation system using accelerometers and magnetometers. This substitution eliminates the harmful effects of sound propagation in seawater (affected by temperature, salinity, pressure) while maintaining the capability to calculate position, direction, and distance through mechanical sensing of motion and magnetic field orientation.
2Loss of information
If manual navigation using compass and kick-cycle counting is used, then navigation information can be obtained, but a great deal of uninterrupted attention is required
Solution Approach 1:
The inertial navigation system automatically calculates position, direction, and distance information by processing data from accelerometers and magnetometers without requiring diver intervention. The system performs self-service navigation functions including automatic integration of acceleration data to derive velocity and position, eliminating the need for manual kick-cycle counting and continuous compass monitoring.
Solution Approach 2:
The patent applies computational algorithms that rapidly process and integrate sensor data in real-time, accelerating the navigation information generation process. The microprocessor continuously integrates accelerometer data to calculate velocity and position changes, providing updated navigation information at high frequency without requiring diver attention or manual calculations.
3Loss of information
If ultrasound based devices are used, then navigation information can be provided, but they are bulky and power hungry
Solution Approach 1:
The patent employs compact, low-power inertial sensors (accelerometers and magnetometers) that are significantly smaller and lighter than ultrasound transducers and processing equipment. These miniaturized sensors provide sufficient navigation information for diving applications without the bulk and power consumption of acoustic systems, representing a more efficient, short-lived solution optimized for the specific application.
4Loss of information
If underwater cable communication is used, then location information can be obtained, but there is a risk of entanglement
Solution Approach 1:
The patent extracts the navigation information processing capability from the surface and places it entirely on the diver's wrist unit. The inertial sensors and microprocessor on the diver independently calculate position, direction, and distance without requiring any connection to surface equipment. This extraction eliminates the underwater cable entirely, removing the entanglement hazard while maintaining continuous location information availability.
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
The system enhances navigation accuracy and reliability by calculating velocity and heading, mitigating the effects of sea currents and providing precise distance information, while being safer and more efficient than existing methods.
Implementation Method 1
at least an accelerator sensor and a magnetometer are arranged in the sensor unit
Implementation Method 2
at least an accelerator sensor and a magnetometer are arranged in the sensor unit
Data Source
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Figure 5
AI summary
The invention relates to a method for generating underwater navigational information. In the method input data is received from a user, inertial data is obtained from inertial sensors, an estimation of a propulsion power produced by the user at a predetermined points of time is calculated at least partly based on the obtained inertial data, a hydrodynamic coefficient is calculated for the user at least partly based on the input data by the user, a velocity of the user is calculated at least partly on a basis of the estimated propulsion power and the determined hydrodynamic coefficient, heading information of the user at the predetermined points of time is calculated from the obtained inertial data, the calculated velocity information is combined with the calculated heading information at corresponding points of time and navigational information is generated. The invention also relates to an apparatus and to a system.