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Autonomous Crane System for Payload Motion Control


OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy OBJECTIVE: Develop technology to eliminate or greatly reduce the need for tag line handlers when transferring boats, craft, and other cargo loads. DESCRIPTION: Crane lifting operations are inherently hazardous. Loads suspended from a single hook store substantial potential energy and are not easily controlled when the crane is attached to the deck of a ship that is moving in response to the wind and wave conditions at sea. In order to lift and maneuver large cumbersome loads aboard ships, tag line handlers are used to prevent unsafe pendulation and unwanted rotations. Tag line handlers are frequently exposed to hazards because the lines must be tended on a moving deck, which can be wet from sea spray or rain, and be in close proximity to the moving payload. The Navy seeks the development of a cargo stabilization system to accommodate different load types in a safe and timely manner without requiring assistance from tag line handlers. The desired solution will operate effectively without a load on the hook and up to the rated Safe Working Load (SWL) of the crane. Horizontal oriented loads such as boats as well as vertically oriented loads will be accommodated and stabilized. The system shall be capable of accommodating 6 degree of freedom ship motions on an Expeditionary Fast Transport (EPF) in sea state 3 (as defined by NATO STANAG 4194) and must be capable of performing a minimum of 5 lifts in less than an hour. Navy is seeking a system that can stabilize the load for the entire duration of the time it is suspended. The commercial industry approach to this challenge is to design special purpose lifting devices, which are often designed in conjunction with the platform from which they will operate, to incorporate mechanisms to isolate the lifting device from the platform motion. The solution sought by the Navy is more general purpose and must be applicable to existing crane installations and capable of lifting a variety of cargo types. The solution sought by the Navy differs from commercial off-the-shelf approaches in that it should be able to be implemented on existing cranes with reasonable modifications. If the crane is installed on a vessel that launches and recovers watercraft with personnel aboard, then the system must comply with the Personnel Lifting requirements listed in the ABS Guide for Certification of Lifting Appliances [Ref 3]. PHASE I: Develop a computer model concept for an autonomous cargo stabilization system. Navy is seeking a system that can stabilize the load for the entire duration of the time it is suspended. Feasibility shall be demonstrated by a combination of analysis, modeling, and simulation. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II. PHASE II: Develop and deliver a detailed design of a full-scale stabilization system. Fabricate a prototype scale working model of the stabilization system at no smaller than a 1/9th geometric scale. Demonstrate the stabilization on an appropriately scaled model of an ISO standard twenty-foot equivalent (TEU) container, while being subjected to motions representative of a fully developed high-end sea state 3 on an Expeditionary Fast Transport (EPF). PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning a full scale stabilization system to Navy use through testing and further development to facilitate the adaptation of the technology to Navy use in shipboard applications at sea state 3. The use of stabilization system technology being sought by the Navy to facilitate moving equipment and cargo using cranes aboard ships had its start in private industry to improve both worker safety and to reduce the time required operating cranes in order to construct multi story high rise buildings. Construction of offshore wind farms is another area where shipboard cranes and stabilization during lifting operations is required. This need is expected to grow significantly in the area of load management on land and on the sea. REFERENCES: 1. “NATO STANAG 4194, Standardized Wave and Wind Environments and Shipboard Reporting of Sea Conditions, 6 April 1983.” 2. “ASTM STP-SA-055, Guide to Mobile Crane Standards.” The American Society of Mechanical Engineers - work sponsored by ASME Safety Codes and Standards and the ASME Standards Technology, LLC (ASME ST-LLC), December 21, 2012. 3. “Guide for Certification of Lifting Appliances,” American Bureau of Shipping, December 2021. KEYWORDS: Dynamic Stabilization; Shipboard Cranes; Cargo Pendulation; Wave Induced Ship Motion; Sea State; Tag Line Handlers
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