STABILIZATION OF HELICOPTER SLING
LOADS
Vefa Narli
1
Introduction
•
•
•
•
High Rise Rescue
Fire Fighting
Offshore
Construction
• Hover
• Vertical Take-off
and Land
2
Transportation Modes of Helicopters
23000
lbs
40000
lbs
5000
lbs
3
Helicopter Sling Loading Capacities
Reference
Helicopter
Helicopter
Weight
External Load
Weight
Load Mass
Ratio
Cable Length
NA
NA
NA
0.33
NA
NA
NA
39800 lbs (max)
NA
12-16 ft
3
( Handling Qualities
Requirements for Military
Rotorcraft, Aeronautical Design
Standard)
4 (Requirements for the
Certification of Sling
Loaded Military
Equipment for External
Transportation by
Department of Defense
Helicopters )
7
UH-60A
14600 lbs
1130-6384 lbs
0.07-0.30
23 ft (single)
15.83 ft (4-legged)
7
NA
NA
40000 lbs
NA
3-140 ft
11
UH-60
16000 lbs
1102-4409 lbs
0.06-0.22
9.84-26.2 ft
Kaman
K-1200
12000 lbs
6000 lbs
0.33
NA
Superior
Helicopter
4
Helicopter Sling Loading
• Load is suspended beneath
the helicopter
• Free to rotate in all 3 axis
• Long cable lines are used
• Requires pilot effort
5
Literature Survey
•
•
•
•
•
•
•
•
•
•
Dukes, T. A., “Maneuvering Heavy Sling Loads Near Hover, Part I: Damping the
Pendulous Motion,” Journal of the American Helicopter Society, Vol. 18, (2), Apr.
1973.
Dukes, T. A., “Maneuvering Heavy Sling Loads Near Hover, Part II: Some Elementary
Maneuvers,” Journal of the American Helicopter Society, Vol. 18, (3), July 1973.
Poli, C., and Cromack, D., “Dynamics of Slung Bodies Using a Single-Point
Suspension System,” Journal of Aircraft, Vol. 10, (2), Feb. 1973.
Cliff, E. M., and Bailey, D. B., “Dynamic Stability of a Translating Vehicle with a
Simple Sling Load,” Journal of Aircraft, Vol. 12, (10), Oct. 1975.
Nagabhushan, B. L., “Low-Speed Stability Characteristics of a Helicopter With a
Sling Load,” Vertica, Vol. 9, 1985.
Sheldon, D. F., “An Appreciation of the Dynamic Problems Associated with the
External Transportation of Loads from a Helicopter—State of the Art,” Vertica, Vol. 1,
1977.
Prabhakar, A., “Stability of a Helicopter Carrying an Underslung Load,” Vertica, Vol.
2, 1978.
Cicolani, L. S., Kanning, G., and Synnestvedt, R., “Simulation of the Dynamics of
Helicopter Slung Load Systems,” Journal of the American Helicopter Society, Vol. 40,
(4), Oct. 1995.
Gabel, R., and Wilson, G. J., “Test Approaches to External Sling Load Instabilities,”
Journal of the American Helicopter Society, Vol. 13, (3), July 1968.
6
HSL Flight Tests
[7]
7
Stability of HSL - I
[7]
8
Stability of HSL - II
[7]
9
Stability of HSL - III
Level 1 – Load maintains directional
stability throughout the maneuvers.
Minimal oscillation. Requires minimal
concentration by the flight crew
[ 11]
Level 2 – Load may oscillate, rotate.
Directional orientation is not stable. Does
10
not pose a threat to the aircraft. ost
maneuvers. Moderate oscillation.
Safety - I
Manwaring, J. C., Conway, G. A., Garrett, L. C., “Epidemiology and Prevention
of Helicopter External Load Accidents,” Journal of Safety Research, Vol. 29,
No. 2, pp. 107-121, 1998.
11
Safety - II
• …The helicopter departed with a 150-foot long-line
attached and no external load on the hook… After liftoff, the long-line tangled in the trees, causing the
helicopter to crash…
• …An Aerospatiale 316B was moving equipment in
mountainous terrain with a 100-foot long cable… the
cargo hook snagged on an equipment trailer adjacent
to the take-off area. As the tension on the line
increased, the hook broke free of the trailer and the
cable recoiled into the main rotor blades, rendering the
helicopter uncontrollable…
• …During the flight to reposition the helicopter that was
transporting seismic equipment with a 100-foot long
line, the load caught on a nearby fence…
12
Literature Survey
• Lucassen, L. R., and Sterk, F. J., “Dynamic
Stability Analysis of a Hovering Helicopter With
A Sling Load,” Journal of the American
Helicopter Society, Vol. 10, (2), Apr. 1965.
• - 2001 (Dynamics and Stability)
• Stiles et al, (2004, [22],) mention sling load
active stabilization as a future direction of
research in his review of Helicopter AFCS.
13
Statement of the Problem
• Keep the oscillations of
the payload under a
critical angle, or
deviation
• The effect of the load on
the helicopter dynamics
should not exceed more
than 10% of the static
weight of the load.
• System should be
adjustable to different
line length and load
weight and should be
robust to 10% changes
of the nominal values.
14
Approach - I
• Modified AFCS that stabilizes the slung
load
• Stand-alone stabilizing system
– Cartesian mechanism
– Spherical mechanism
15
Approach - II
[2]
Cho, S.-K., Lee, H. H., “An Anti-Swing Control of a 3-Dimensional
Overhead Crane,” Proceedings of the American Control Conference, Chicago, Illinois,
pp. 1037-1041, 2000.
16
Future Work
•
•
•
•
Anti-sway control of shipboard boom cranes
Simulations of a quadrotor suspended mass
Update the statement of the problem
Stabilization of a 3D suspended pendulum with
a cartesian mechanism
• Stabilization of a 3D suspended pendulum with
a spherical mechanism
• UH-60 helicopter MatLAB model
• Simulations of 3D suspended pendulum
attached to UH-60
17
References
1. Abdel-Rahman, E. M., Nayfeh, A. H., Masoud, Z. N., “Dynamics and Control of Cranes: A
Review”, Journal of Vibration and Control, 9, pp. 863-908, 2003, cited by 15.
2. Alleyne, A., Hedrick, J. K., “Nonlinear Adaptive Control of Active Suspensions,” IEEE
Transactions on Control Systems Technology, Vol. 3, No. 1, pp. 94-101, 1995, cited by 123.
3. Anonymous, “Handling Qualities Requirements for Military Rotorcraft, Aeronautical Design
Standard,” ADS-33E-PRF, 2000.
4. Anonymous, “Requirements for the Certification of Sling Loaded Military Equipment for External
Transportation by Department of Defense Helicopters”, MIL-STD-913A, 1997.
5. Balachandran B., Li, Y.-Y., Fang, C.-C., “A Mechanical Filter Concept For Control of Non-linear
Crane-Load Oscillations”, Journal of Sound and Vibration, 228, pp. 651-682, 1999, cited by 12.
6. Bartolini, G., Pisano, A., Usai, E., “Second-order Sliding-Mode Control of Container Cranes”,
Automatica 38 pp. 1783-1790, 2002, cited by 11.
7. Cicolani, L. S., Sahai, R., Tucker, G. E., McCoy, A. H., Tyson, P. H., Tischler, M. B., Rosen, A.,
“Flight Test Identification and Simulation of a UH-60A Helicopter and Slung Load”, NASA/TM2001-209619, USAAMCOM-TR-01-A-001, 2001.
8. Corriga, G., Giua, A., Usai, G, “An Implicit Gain-Scheduling Controller for Cranes”, IEEE
Transactions on Control Systems Technology, Vol. 6, No. 1, pp. 15-20, 1998, cited by 36.
9. Fang, Y, Dixon, W. E., Dawson, D. M., Zergeroglu, E., “Nonlinear Coupling Control Laws For An
Underactuated Overhead Crane System”, IEEE/ASME Transactions on Mechatronics, Vol. 8,
No. 3, pp. 418-423, 2003.
10. Fliess, M., Levine, J., Rouchon, P., “A Simplified Approach of Crane Control Via A Generalized
State-Space Model”, Proceedings of the 30th Conference on Decision and Control, England,
pp. 736-741, 1991, cted by 29.
11. Fusato, D., Guglieri, G., Celi, R., “Flight Dynamics of an Articulated Rotor Helicopter with an
18 by
External Slung Load,” AHS International Annual Forum, 55th, Montreal, Canada, 1999, cited
8.