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Hydrodynamic Control of a Towed Vertical Array


TECHNOLOGY AREA(S): Sensors, Electronics, Battlespace 

OBJECTIVE: Develop a method and/or apparatus to ensure vertical posture (and potentially allow control of the same) of the vertical orientation of the array system while deployed by a surface ship. 

DESCRIPTION: The Navy is seeking a way to ensure the suspended array remains vertical while deployed in the water in order to ensure most effective use of the system. The Surveillance Towed Array Sensor System (SURTASS) is an array system that is deployed on surface ships with acoustic data collection capabilities. SURTASS includes a tethered vertical array that consists of small, lightweight acoustic transmitters suspended by cable beneath a surface ship. The vertical array comprises 19 individual bodies, of which the top one is a tow bar assembly and the other eighteen are identical projector assemblies. The distance from the tow bar to the top projector is 10 feet, and the projector assemblies are spaced 6 feet apart. The tow body assembly weighs approximately 2,400 lbs. in water and each of the projector assemblies weighs approximately 1,400 lbs. in water. Adding the suspension members, cabling, and miscellaneous parts results in a submerged array weight of 28,700 lbs. Each of the assemblies is 20 feet wide and 136 feet long. Below the tow bar and between the projector assemblies, there are two suspension members, one forward and one aft, 99 feet apart. The tow bar is supported from a single cable from the ship, which is 34 feet aft of the forward vertical support below and coincides with the center of gravity of the array so that the array hangs vertical with the tow bodies horizontal until hydrodynamic drag is applied. The ship maintains an average speed of approximately 6 kilometers per hour (3.2 knots) when operational. There is a need to ensure the suspended array remains vertical while deployed in the water in order to ensure effective use of the system. Currently, the vertical array demonstrates a constant “kite” angle at operational speeds. The innovation needed is an approach or mechanism that can be added to the vertical array or deployment system that both autonomously and dynamically ensures it remains in a vertical plane while deployed in the water, while not inducing turbulence or acoustic noise. The product for this effort is a method and/or apparatus to ensure vertical posture (and potentially allow control of the same) of the array system while deployed by a surface ship. 

PHASE I: During Phase I, derive the technical functional requirements to develop a concept for a dynamic vertical-angle control system for the tethered vertical array. Demonstrate feasibility for their concept design to implement autonomous, dynamic control of a vertical array, including mechanical, electronic, and software components by simulating or modeling a variety of potential ocean environments and ship movements as well as by analytical demonstration. (The Navy will provide data regarding relevant ocean environments and will provide sufficient technical details to enable accurate modeling of the ships’ movements within the range of required sea states and ship speed.) The Phase I Option, if awarded, will include the initial design specifications and capabilities description to build a prototype in Phase II. Develop a Phase II plan. 

PHASE II: Based on the Phase I results and the Phase II Statement of Work (SOW), design, develop, and deliver a prototype vertical angle control system. Develop and construct a working scale model of a surrogate vertical array; develop a test plan; identify a test facility; and develop required test fixtures needed to support laboratory or at-sea testing. Support the testing and performance analysis and validate that the prototype operates in accordance with the model in a laboratory or at-sea environment. Incorporate lessons learned from these tests into a full system design, develop the technical specifications, and interface documentation required for the control system to be integrated into the target array. Prepare a Phase III development plan to transition the technology for Navy and potential commercial use. 

PHASE III: Support the Navy in transitioning the technology to Navy use. Based upon prototype test results, design a production-ready control system to be integrated into a specific array design identified by the Navy or a commercial array manufacturer. Build a control system; and refine, fabricate, and implement the developed hardware to suit the operation of a vertical array. Support integration and testing in laboratory and ocean environments to meet requirements for functionality, environmental extremes, reliability, safety, and other requirements to certify the system for Navy use. This topic will enable SURTASS ships to perform missions in ocean environments that limit today’s acoustic performance. Other Navy platforms (ships and submarines), the oil exploration industry, and ocean scientists use similar acoustic arrays and have an equivalent unfulfilled requirement for improved depth control. Successful execution of the described capabilities would benefit all of these other users for similar reasons. 


1: Tseng, Yi-Hsiang, Chen, Chung-Cheng, Lin, Chung-Huo, Hwang, and Yuh-Shyan. "Tracking Controller Design for Diving Behavior of an Unmanned Underwater Vehicle." Hindawi Publishing Corporation, Mathematical Problems in Engineering, Volume 2013, Article ID 50454.

2:  Baviskar, Abhijit, Feemster, Matthew, Dawson, Darren, and Xian, Bin. "Tracking Control of An Underactuated Unmanned Underwater Vehicle." 2005 American Control Conference, June 8-10, 2005.

3:  Li, Haocheng, Olinger, David J., and Demetriou, Michael A. "Passivity based control of a Tethered Undersea Kite energy system." IEEE American Control Conference (ACC), 2016.

4:  Williams, Paul. "Optimal Wind Power Extraction with a Tethered Kite." AIAA Guidance, Navigation, and Control Conference and Exhibit, Guidance, Navigation, and Control and Co-located Conferences, 21-24 August 2006.

5:  Chung, Soon-Jo, and Miller, David W. "Propellant-Free Control of Tethered Formation Flight, Part 1: Linear Control and Experimentation." Journal of Guidance, Control and Dynamics, Vol. 31, No 3, May-Jun 2008.

KEYWORDS: Vertical Array; SURTASS; Acoustic Data Collection Capabilities; Streamed Array At Speed; Lightweight Acoustic Transmitters; Constant “Kite” Angle At Operational Speeds 


Mandeep Nehra 

(401) 832-9174 

Mr. Ray Cooke 

(619) 524-7032 

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