This software implements a motion-planning module for a maritime autonomous surface vehicle (ASV). The module trails a given target while also avoiding static and dynamic surface hazards. When surface hazards are other moving boats, the motion planner must apply International Regulations for Avoiding Collisions at Sea (COLREGS). A key subset of these rules has been implemented in the software. In case contact with the target is lost, the software can receive and follow a “reacquisition route,” provided by a complementary system, until the target is reacquired. The programmatic intention is that the trailed target is a submarine, although any mobile naval platform could serve as the target.
The algorithmic approach to combining motion with a (possibly moving) goal location, while avoiding local hazards, may be applicable to robotic rovers, automated landing systems, and autonomous airships. The software operates in JPL’s CARACaS (Control Architecture for Robotic Agent Command and Sensing) software architecture and relies on other modules for environmental perception data and information on the predicted detectability of the target, as well as the low-level interface to the boat controls.
This work was done by Michael Wolf, Yoshiaki Kuwata, and Dimitri V. Zarzhitsky of Caltech for NASA’s Jet Propulsion Laboratory.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
Innovative Technology Assets Management
JPL
Mail Stop 321-123
4800 Oak Grove Drive
Pasadena, CA 91109-8099
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
NPO-48115
This Brief includes a Technical Support Package (TSP).
Target Trailing With Safe Navigation for Maritime Autonomous Surface Vehicles
(reference NPO-48115) is currently available for download from the TSP library.
Don't have an account?
Overview
The document titled "Target Trailing With Safe Navigation for Maritime Autonomous Surface Vehicles" outlines a motion planning software developed by NASA's Jet Propulsion Laboratory (JPL) aimed at enabling Autonomous Surface Vehicles (ASVs) to effectively trail designated targets while ensuring safe navigation in maritime environments. The software addresses several challenges inherent in this task, including the integration of track-and-trail behavior with safe navigation protocols, particularly the International Regulations for Avoiding Collisions at Sea (COLREGS).
Key challenges identified include:
-
Multiple Objectives: The software must balance competing objectives, such as maintaining contact with a target while adhering to safety regulations. This requires arbitration between behaviors or multi-objective optimization to find a suitable compromise.
-
Temporal Considerations: Unlike traditional waypoint navigation, trailing a target is time-sensitive, necessitating precise maneuvering to maintain target acquisition.
-
Dynamic Environment: The maritime environment is unpredictable, with other vessels and obstacles moving in unstructured ways, complicating navigation.
-
Uncertainty and Noise: The software must account for uncertainties in sensor data and environmental conditions, including the effects of sea motion on vehicle stability.
-
Resource Limitations: The software operates on a real-time embedded system with constraints on power and processing speed, necessitating efficient algorithm choices.
The software architecture is divided into two main components: a strategic planner and a local planner. The strategic planner interprets target detectability maps and reacquisition routes to generate a queue of waypoint goals for the ASV, which may include specific arrival times and headings. The local planner is responsible for safely achieving these waypoint goals while avoiding hazards and complying with COLREGS.
The input data for the software includes information about surrounding sensor contacts (e.g., other vessels, buoys), predicted detectability maps, reacquisition routes, and the ASV's own state information. The motion planning software aims to maintain contact with the target while avoiding collisions and following safe navigation rules. In scenarios where contact with the target is lost, the software utilizes reacquisition routes to regain contact.
Overall, this document highlights the innovative approach taken by JPL to enhance the capabilities of ASVs in maritime navigation, emphasizing the importance of safety, efficiency, and adaptability in dynamic environments.
