N112-137 TITLE: Active Motion-Compensation Technology for Roll-On/Roll-Off Cargo Vessel Discharge to Floating Platforms

TECHNOLOGY AREAS: Ground/Sea Vehicles, Battlespace

ACQUISITION PROGRAM: PMS 385, CAPT Sutton

OBJECTIVE: The goal of this topic is to develop an innovative approach and the associated technologies to permit deployment and vehicle transfer across a commercial Roll-on/Roll-off (Ro/Ro) ship stern ramp to a floating platform in up to a sea state 5 environment. Proposed concept(s) should not require modifications to the ramp structure, but rather rely on a separate, active system driven by sensed motions to isolate the ramp from the environment.

DESCRIPTION: The military transportation system includes the use of commercial Ro/Ro ships for cargo and vehicle stowage as well as transport and delivery � particularly when participating in disaster relief or humanitarian assistance operations. Ramps are currently used as a means to bridge the gap between an independently floating vessel and a floating platform or barge to facilitate the transfer of cargo. Commercial Ro/Ro ship ramps are designed for operations in calm water environments, no greater than sea state 3. If a protected harbor is not accessible, the Ro/Ro ship may have to discharge cargo over its ramp to a floating platform in an open water environment which would increase the probability of encountering sea states of 3 or more. Additionally, both the vessel and the platform will have pitch, heave and roll characteristics that will likely be different from each other creating relative motions between the two ends of the ramp. The motions will also impart accelerations to the vehicle driving across the ramp. In order to successfully discharge the ship�s cargo, a vehicle operator must be able to safely drive a vehicle out of the Ro/Ro ship, across its stern cargo ramp, and onto the platform. With the Ro/Ro ship and the platform exposed to waves, the relative motion will cause the ramp to heave and torque in a more extreme manner than would typically be seen in a protected harbor environment. Use of the current state-of-the-art would severely restrict cargo movement operations in order to comply with the requirement for use in lower sea-states. Use of the state-of-the art in higher sea-states would likely cause damage to the ramp structure and its attachment to the ship as well as create unsafe conditions for personnel transiting the ramp in vehicles.

This topic seeks an innovative approach and associated technologies to develop a ramp interface or a coupling mechanism concept that uses an active system approach to compensate for the induced motions (linear and rotational) and forces while vehicles are being transferred from a vessel to a platform during in up to sea state 5 conditions. Implementation of the proposed concept (s) should not require modifications to either ship or ramp structures and should employ open architecture design principles to maximize adaptability and flexibility of use. An anticipated technical challenge will be in the ability to employ a motion sensing and structural monitoring coupled to an actuation concept to isolate the ramp from the motion environment and assure operating loads are within allowable limits. The emphasis should be on sensing and actuation systems architecture and development of algorithms for determining the safe operating load on the structure in the dynamic environment and in relation to its rated capacity. For purposes of focusing proposals in this topic area, the Large Medium Speed Roll-on/roll-off (LMSR) and its existing stern ramp for will be the baseline. Detailed information about the LMSR can be found in Ref (4). The ramp on the LMSR is 100 feet long with a clear driveway that is 16 feet wide. It has a truss structure along its two long sides to provide vertical plane bending stiffness. The ramp has a design load of 80 tons and is rated for operations in up to sea state 3. The weight of the ramp itself is 100 tons. It is hinged at the ship end to allow the ramp to pitch and slew relative to the stern of the vessel. With other vessels, such as commercial Ro/Ro ships the height of the ramp at the transom could vary over a range from 8 feet to 16 feet above the waterline. The ramp applies significant vertical loads on the platform deck and point loads get very large at the ramp corners when the vessels have significantly different motions induced by the seaway. The maximum weight supported by the foot is half the ramp weight plus the maximum gross vehicle weight. Proposed concepts should allow for the torsion associated with the relative motions between the ends of the ramp while also providing adequate strength and stiffness.

PHASE I: Develop an innovative approach and associated technologies for a ramp interface concept that will compensate for motions (linear and rotational) and forces while vehicles are being transferred from a vessel to a waiting platform during in up to sea state 5 conditions. Assess feasibility and establish performance goals. As part of this task the contractor should estimate the size of all major components that make up the conceptual design along with an explanation of how the system operates. As practicable, modeling and simulation to include animations of the dynamic aspects of the concept are encouraged. Provide a Phase II development approach and schedule that contains discrete milestones for product development.

PHASE II: Develop, fabricate and demonstrate a proof-of-concept system as identified in Phase I. In a laboratory environment, demonstrate that the system concept can meet the performance goals established during Phase I. As applicable, provide a preliminary detailed design package including supporting calculations, a plan for software and/or hardware certification, validation, and method of implementation into a future ship test and/or design environment. Prepare cost estimates, and interface documents for use in both forward fit and retrofit ship programs.

PHASE III: If the Phase II effort is deemed appropriate for demonstration, the contractor will be tasked to prepare a detail design and build, install and demonstrate a full scale system that would permit transfer of vehicles from a Government provided Ro/Ro ship to a Government provided platform in up to sea state 5 conditions.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Commercial Ro/Ro ships can utilize this technology to broaden their ability to offload in port locations marginally protected from the sea.

REFERENCES:
1. http://en.wikipedia.org/wiki/Roll-on/roll-off

2. "Guide for Certification of Stern, Bow and Sideport Ramps and Moveable Platforms (Decks)," ABS Guide for Certification of Lifting Appliances, Chapter 6.

3. http://www.globalsecurity.org/military/systems/ship/inls.htm

4. http://www.msc.navy.mil/factsheet/lmsr.asp

KEYWORDS: Dynamic interface; Vehicle transfer; Relative ship motions; Ramp structures; Ro/Ro; RRDF

** TOPIC AUTHOR (TPOC) **

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