Speaker
Description
Precise position control is essential for the safe operation and automatic berthing/unberthing of autonomous ships. Although studies on automatic berth/unberthing and close passing have been conducted in ports or narrow waterways, there are not many studies determining potential contact between objects in the process. This is because a sophisticated model that can accurately represent the shape of a ship must be used to determine the contact at a close distance. There are not many examples of implementing this by applying it in the current simulator and it is difficult to develop a technique that can reflect the influence of contact by applying path planning and control algorithms while considering various fluid forces in a narrow sea area. The starting point is to accurately determine the contact situation between ship and ship or between ships and quay walls.
In this study, we present a basic approach to detect ship-to-ship or ship to quay contact in a narrow sea area using collision detection techniques widely used in the game engines. In general, collision processing consists of a collision detection step in which objects collide with each other and a response to the collision. For several geometric models that require collision analysis, a response is made through a collision detection algorithm.
After subdividing the ship CAD model using Blender, the V-HACD technique was applied to each bounding volume. In this way, after specifying the collision point, it can be utilized to make a reaction to the contact considering hydrodynamics using specialized simulators. Compared to the original mesh model consisting of about 240,000 vertices and 120,000 triangles, the time required for the calculation can be reduced by significantly reducing the number of bounding volumes required for collision detection. It is possible to configure a fast collision calculation using the tree structure of the convex hulls.
References
Montanari, M., Petrinic, N. and Barbieri, E., 2017. Improving the GJK algorithm for faster and more reliable distance queries between convex objects. ACM Transactions on Graphics, 36(3), pp.1-17.
Approximate convex decomposition and transfer for animated meshes. ACM Transaction on Graphics, 37(6), pp.1-10
| Keywords | autonomous ships, collision detection, bounding volume hierarchy, |
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