Hybrid Solver for Underwater Vehicle Towing Simulations
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Solution Overview
Problem
Current simulators for underwater vehicle maneuvering and control, such as DCAB and OrcaFlex, are unable to handle discontinuous dynamics like cable release or capture due to their reliance on implicit methods, which break down under impulse loads, limiting their ability to simulate complex scenarios effectively.
Innovation Solution
The Maneuvering and Control Simulator for Underwater Vehicles (MACSUV) uses a hybrid explicit/implicit numerical solver and a graphical programming environment to simulate towing-related operations, including underwater vehicle interactions with tow cables, allowing for the representation of discontinuous dynamics and environmental influences like waves and currents, with a fully functional UUV controller block and autocode generation for real UUV microcontrollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If implicit solution methods are used to solve for states of underwater vehicles and cables, then numerical convergence is achieved over continuous loads, but the solver breaks down when impulse loads are applied such as cable release or capture
Solution Approach 1:
The patent applies dynamics by making the numerical solution method adaptive rather than static. The solver dynamically switches between implicit and explicit methods based on the current simulation state and detected events. When continuous loading conditions prevail, implicit methods maintain numerical convergence. When discontinuous events like cable release or capture occur, the solver transitions to explicit methods to handle impulse loads, thereby resolving the contradiction between solver reliability and adaptability to discontinuous dynamics
Solution Approach 2:
The patent changes the parameter of numerical solution method from a fixed implicit approach to a variable approach that selects between implicit and explicit methods. This parameter change allows the system to optimize solver performance based on loading conditions, achieving both numerical convergence during continuous operation and proper handling of discontinuous events through method switching
2Reliability
If model testing is used to observe underwater vehicle maneuverability, then effective performance verification is achieved, but the process takes months or years to prepare and is the most expensive approach
Solution Approach 1:
The patent creates a virtual copy of the physical model testing environment through computer simulation. The simulator replicates underwater vehicle dynamics, cable behavior, and environmental conditions, allowing performance verification without physical prototypes. This copying approach maintains the reliability of performance assessment while eliminating the months or years of preparation time and high costs associated with building and testing physical models
Solution Approach 2:
The patent substitutes the mechanical physical testing system with a computational simulation system. Instead of physically constructing models and conducting water tank or field tests, the system uses numerical algorithms to simulate vehicle dynamics, cable mechanics, and hydro environmental interactions, replacing the mechanical testing infrastructure with software-based virtual experimentation
3Productivity
If implicit methods are used in simulators like DCAB and OrcaFlex, then effective simulation in most scenarios is achieved, but the simulators cannot handle discontinuous dynamics such as cable release or capture
Solution Approach 1:
The patent implements multi-functionality by enabling the simulator to perform both implicit and explicit solution methods within a single unified framework. This universal approach allows the same simulation platform to effectively handle both continuous loading scenarios (using implicit methods) and discontinuous events like cable release or capture (using explicit methods), thereby increasing both productivity across scenarios and adaptability to diverse operational conditions
Data Source
AI summary
The main components of an exemplary inventive simulation are a towing platform (such as a ship), a towed body, an underwater vehicle (such as a UUV), and a tow cable connecting the towing platform and the towed body. An objective of the dynamic arrangement of the components is to perform a “line capture” of the moving vehicle by the cable. Respective motions and positions of the towing platform and the towed body affect the cable. Waves and currents in the water, as well as changes in catenary and tension of the cable, affect the tow body. Advantageously, the invention more accurately accounts not only for continuities, but also for discontinuities, characterizing the dynamic interrelationships between and among the components. Among the invention's features is its ability to “trigger” consideration of certain dynamic manifestations relating to the vehicle, depending on whether or not the vehicle is in a captured state.