COLREGs- Compliant ASV Path Planning in River
By: Mei Jian Hong (PhD Student)
The COLREGs consists of five parts and 38 rules. ‘Part A: General’ is the regulations of the application and responsibility. ‘Part B: Steering and sailing’ regulates the rules of marine crafts navigation. ‘Part C: Lights and shapes’ regulates the use of lighting signals. ‘Part D’ is Sound and light signals and ‘Part E’ is Exemption.
Rules 13 to 15 in Part B regulate three scenarios, i.e. overtaking, head-on and crossing, which are as follows.
Rule 13. Overtaking:
An overtaking vessel must keep out of the way of the vessel being overtaken.
Rule 14. Head-on situations:
When two power-driven vessels are meeting head-on both must alter course to starboard so that they pass on the port side of the other.
Rule 15. Crossing situations:
When two power-driven vessels are crossing, the vessel which has the other on the starboard side must give way and avoid crossing ahead of her.
Besides, Rule 9 regulates the narrow channel waterway, such as riverine environment.
Rule 9. Narrow channels:
A vessel proceeding along a narrow channel must keep to starboard.
Small vessels or sailing vessels must not impede (larger) vessels which can navigate only within a narrow channel.
Ships must not cross a channel if to do so would impede another vessel which can navigate only within that channel.
In summary, the ASV has to make an evasive manoeuvre and avoid the encountered obstacles from starboard side.
2.COLREGs-Compliant ASV Path Planning in River
(b) head on
Figure 1. Simulation of overtaking and head-on scenarios
Figure 1 shows the simulation results of the COLREGs-compliant path planning in overtaking and head-on scenarios. The ASV is forced to bypass the static and dynamic obstacles from starboard side, which is compliant with COLREGs.