SBIR-STTR Award

ATR has proposed an interface system concept, Compensated Ramp Interface System (CRIS), comprised of a landing platform and a transfer platform. The landing platform provides continuous support to the ramp, and the transfer platform provides a transition interface for a vehicle to cross from the landing platform onto the floating platform deck. A monitoring and situation awareness system will be used to monitor wave environment and assure operating loads are within allowable limits. The CRIS concept eliminates undesired sliding between the ramp foot and floating platform as currently happens during a Roll-on/Roll-off vehicle transfer between vessels in stream. This proposed approach takes advantage of recent developments in robotics, mechanism design, and sensing and control technology. The system will be designed with open architecture principles to maximize adaptability and flexibility of use.

Benefit:
Existing stern ramps of commercial Roll-on/Roll-off (Ro/Ro) ships are restricted to be used in calm water conditions, no greater than sea state 3. The proposed Compensated Ramp Interface System (CRIS) will provide an actively motion compensated interface which will isolate the ramp from the environment. As a result, a sea state 3 capable ramp can be safely deployed for Ro/Ro vehicle transfer operations in up to sea state 5 conditions. The system will not require any modifications to the ramp structure. It is equipped with advanced sensing technologies for wave and current environment, ramp and ship motions, and ramp dynamical loads. The interface will be enhanced with a monitoring and situation awareness system for safe operations. Such an interface technology will enable the US Navy and TRANSCOM to safely use the existing commercial Ro/Ro ship stern ramps for vehicle transfer in up to sea state 5. The technology also has a good potential to be adopted by commercial sectors around the world.

Keywords:
Stern Ramp, Stern Ramp, Vehicle transfer, motion platform, motion compensation, Floating Platform, Active control, roll-on/roll-off

The overall goal of this Phase II project is to develop a motion compensating platform (MCP) technology for the 32MJ Electromagnetic (EM) railgun aboard the Joint High Speed Vessel (JHSV). Ship motion for the catamaran is significantly different from a monohull such as the DDG 51. Both its peak linear and peak angular accelerations will be higher than those for a monohull in high sea conditions. Because the current turret train and elevating actuators of the railgun are not designed to accommodate the higher accelerations and higher frequency contents in the ship motions of the JHSV, the Navy has desired to mount the railgun on an MCP so that the turret train and elevating actuators can function as designed. Specific design objective of the MCP includes reducing the linear accelerations by at least 50%. The MCP will also reduce the higher frequency contents to make them similar to those of an uncompensated monohull. A technology demonstrator of the MCP will be developed and tested using a fire control radar as its payload aboard the JHSV in the summer of 2016. The developed MCP technology is scalable for much larger payload should a requirement for supplemental railgun stabilization emerge.

Benefit:
This SBIR Phase II effort is designed to address needs of both the railgun program and PEO Ships, which is providing the JHSV test vessel for FY16 and FY18 railgun demonstrations. The objective technology will reduce risks and facilitate testing of the railgun system at sea, particularly in the more challenging conditions planned for the FY18 demonstrations. Since the railgun and its turret will be designed for deployment on large deepwater vessels, the high acceleration and higher frequency contents environment of the JHSV could present considerable difficulties for the railgun system. The Motion Compensation Platform Demonstrator delivered for the FY16 tests is intended to be scalable for much larger payloads, should a requirement for supplemental railgun stabilization emerge. The MCP may play other roles as well. For example, it may be utilized on land to emulate motions of JHSV or other smaller vessels so that various payloads can be tested economically. Furthermore, the MCP may serve as a stabilizing and buffering interface for a range of other motion-sensitive payloads that may have utility aboard JHSV and other small vessels with similar or even more challenging ship motion characteristics.

Keywords:
Sea State, motion platform, Degrees of Freedom, motion compensation, Joint High Speed Vessel, Ship Motion, stabilization, Electromagnetic Railgun