Hydraulicspneumatics 1992 Cpi Slice

Innovative Ship Relies on Smart Cylinders

Feb. 1, 2003
Markets for the Sea SLICE include the government, commercial and military organizations. A novel linear displacement transducer extends the performance and capabilities of these vessels through closed-loop control.

Lockheed Martin’s SLICE technology is a patented ship design that enables Small Waterplane Area Twin Hull (SWATH) ships to operate at high speeds without sacrificing efficiency. The Sea SLICE prototype shown here is only 105-ft long and 52-ft wide, but is as stable in rough seas as a 350-ft conventional monohull ship.

Markets for the Sea SLICE include the government, commercial and military organizations. All vessel types require stability for both operation and passenger/crew comfort, and would benefit from getting passengers to their destinations quickly.

The key to the SWATH innovation is reduction of wave-making drag, which is accomplished by introducing four teardrop-shaped submerged hulls. Each hull houses a rudder control system, which relies on four smart cylinders from Control Products Inc. (CPI), East Hanover, N. J., to provide controlled motion in two axes. One pair of cylinders controls deflection, and the other controls rotation. The cylinders actuate rudders, which control both the direction and the ride height of the vessel.

Precise, reliable control of the rudders is a big advantage of Sea SLICE technology. Automated rudder control is used to optimize the performance of the ship, constantly modulating position based on feedback from several parameters, including the ship’s attitude and speed. Closed-loop feedback is also used for defining preset fin positions.

Early generation rudder systems used external position sensors coupled to mechanical linkages. These added complexity to the design and created problems with adjustment. The CPI smart cylinder eliminated these problems because its linear displacement transducer resides completely inside it. In fact, these cylinders are not discernable from standard hydraulic cylinders, except for the M12-style electrical connector on the side.

Smart cylinders used in the Sea SLICE use smart cylinders with internally mounted displacement transducers, shown at left, above. These feedback devices do not require center boring the piston rod, which makes installation more convenient and economical.

Mac Stuhler, vice president of CPI, says the smart cylinders use SL Series linear displacement transducers to provide electronic feedback of piston position. “This new, non-contacting, absolute sensor technology was developed to meet the needs of mobile equipment applications.

“Unlike conventional in-cylinder displacement transducers, no center drilling of the rod is required. This provides a huge reduction in installation cost because so little modification to the cylinder is needed. This means virtually any single-rod cylinder design can be converted into a CPI smart cylinder.”

For this application, a shielded cable — which carries supply and feedback signals — plugs into the cylinder via the M 12-style connector. Stuhler continues, “The transducer’s in-line signal conditioner accepts any voltage from 12- to 24- Vdc and provides the controller with a highly repeatable 0.5- to 4.5- Vdc analog output. Because it’s vehicle hardened to ASAE EP455, the transducer stands up to the rugged conditions of this and most other applications.”

Officials at Lockheed Martin see a strong market for a high-speed, fully operational vessel that offers quick response, unlimited operations, while remaining cost-effective. Combining increased speed capability with extraordinary stability in high seas, Sea SLICE technology represents an innovation that opens a new set of options to commercial and military customers. Innovations in electronics for fluid technology, such as CPI smart cylinders, help ensure the advancement of electrohydraulics not only for Lockheed Martin, but a wide range of mobile and industrial applications as well.

Click here to view a video of Lockheed Martin's Sea SLICE in action.

For more information, contact Mac Stuhler at [email protected] or visit www.cpi-nj.com.

Continue Reading

BOOK 2, CHAPTER 12: Fluid Motor Circuits

March 18, 2009
Table of Contents

Motor leakage variations

Oct. 18, 2006
affect low-speed performance

Sponsored Recommendations

7 Key Considerations for Selecting a Medical Pump

Feb. 6, 2024
Newcomers to medical device design may think pressure and flow rate are sufficient parameters whenselecting a pump. While this may be true in some industrial applications, medical...

How Variable Volume Pumps Work

Feb. 6, 2024
Variable volume pumps, also known as precision dispense pumps, are a positive displacement pump that operates by retracting a piston to aspirate a fluid and then extending the...

What is a Check Valve and How Does it Work?

Feb. 6, 2024
Acheck valve, a non-return or one-way valve, is a mechanical device that allows a gas or liquid to flow freely in one direction while preventing reverse flow in the opposite ...

The Difference Between Calibrated Orifices and Holes

Feb. 6, 2024
Engineers tasked with managing fluid flow talk about both holes and calibrated orifices, but they are two distinct entities. A hole can be any opening, but a calibrated orifice...