Inertial Navigation System Integration for Dynamic Positioning Drift Correction
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Solution Overview
Problem
Dynamic positioning systems for marine vessels face challenges in deep water due to long ping cycle times in hydro-acoustic positioning systems, leading to increased thruster usage, mechanical fatigue, and noise, while satellite navigation systems suffer from GPS failures and position jumps, affecting accuracy and fuel efficiency.
Innovation Solution
Integration of an inertial navigation system (INS) with dynamic positioning systems to reduce ping cycle times, correct drift, and enhance position accuracy, using a switch array and controller to automatically select the best PME data for optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hydro-acoustic positioning systems are used in deep water, then position measurement capability is provided, but ping cycle times become long leading to increased thruster usage and mechanical fatigue
Solution Approach 1:
The patent combines multiple positioning systems (hydro-acoustic positioning system and satellite navigation system) with an inertial navigation system into a unified DP system. The INS receives position measurements from both external systems to correct drift, creating a hybrid system that leverages the strengths of each subsystem to achieve accurate positioning with shorter effective ping cycle times.
Solution Approach 2:
The inertial navigation system acts as an intermediary between the hydro-acoustic positioning system and the DP controller. The INS fills the gaps between long hydro-acoustic ping cycles by providing continuous position estimates based on inertial measurements, effectively reducing the impact of long ping cycle times on thruster usage and mechanical fatigue.
2Duration of action of stationary object
If hydro-acoustic positioning systems operate with long ping cycle times, then battery life is extended, but position measurement updates are reduced affecting DP control accuracy
Solution Approach 1:
The inertial navigation system provides self-service by generating continuous position estimates without requiring frequent updates from external positioning systems. The INS uses its own inertial measurements to maintain accurate position tracking between hydro-acoustic pings, eliminating the need to increase ping frequency for maintaining control accuracy.
Solution Approach 2:
The system performs preliminary action by having the INS continuously estimate position based on inertial measurements before external positioning updates are received. This preliminary estimation allows the DP system to maintain accurate control throughout the entire ping cycle, not just at update moments.
3Measurement precision
If satellite navigation systems are used, then position measurements are provided, but GPS failures and position jumps occur affecting accuracy
Solution Approach 1:
The system implements beforehand cushioning by using the inertial navigation system as a backup that can immediately take over when satellite navigation experiences failures or position jumps. The INS provides a cushion against the adverse effects of satellite navigation faults, maintaining system integrity and continuous accurate positioning.
Solution Approach 2:
The DP system uses feedback from multiple sources including the INS and satellite navigation system to detect and correct position jumps or failures. The Kalman filter continuously processes measurements from all sources, using feedback to identify and reject erroneous satellite navigation data while maintaining accurate position estimates through the INS.
4Reliability
If multiple position measuring equipment are integrated, then measurement redundancy is improved, but system complexity increases
Solution Approach 1:
The inertial navigation system serves multiple functions simultaneously: it provides continuous position estimates for DP control, corrects drift from both hydro-acoustic and satellite navigation systems, and acts as a backup during external system failures. This multi-functionality reduces the need for separate dedicated systems for each function.
Solution Approach 2:
The system changes parameters by dynamically adjusting which positioning source the INS uses for drift correction based on availability and quality. The switch array controller can select between hydro-acoustic and satellite navigation data, allowing the system to optimize performance while managing complexity through adaptive parameter selection rather than fixed architecture.
Data Source
AI summary
The present invention provides an improved architecture for integrating an inertial navigation system (INS) into a dynamic positioning (DP) system for a vessel. The architecture includes an INS unit and a DP system having a Kalman filter or other algorithm for combining data supplied by a plurality of position measuring equipment (PME) and the INS unit to derive an estimate of the position or speed of the vessel. A switch array and a switch array controller are also provided. These may optionally form a part of the DP system. The switch array is operable under the control of the switch array controller to supply data supplied by one or more of the plurality of position measuring equipment to the INS unit for the purposes of correcting drift. The selection of which of the one or more PME is/are to be combined with the INS unit is made automatically, in real time, to dynamically optimise the DP system.