Dynamics of a helicopter with a sling load

Ronen, Tuvia; Bryson, Arthur E.; Hindson, William S.

doi:10.2514/6.1986-2288

Cited by 16 publications

(13 citation statements)

References 5 publications

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“…• conventional dynamic derivatives (15) , • transfer function fits to frequency-dependent derivatives (16,17) . The current situation for modelling rectangular box static and dynamic aerodynamics is highly unsatisfactory.…”

Section: Nomenclaturementioning

confidence: 99%

Modelling of static aerodynamics of helicopter underslung loads

Greenwell

2011

Aeronaut. j.

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The complex aerodynamics of rectangular underslung helicopter loads can lead to severe stability problems, but are difficult to represent in flight dynamics models. Current models for box aerodynamics are highly unsatisfactory, being entirely empirical and requiring large amounts of experimental data to generate. This paper presents a new modelling approach, which takes account of the bluff-body nature of the flow, where loads are dominated by normal pressure forces. Existing experimental data is recast in body-axes form, with α and β replaced by velocity components perpendicular and parallel to the box faces. Force and moment data for a wide range of boxes then collapse onto a set of simple generic characteristics, with features that can be related directly to the underlying flow physics. Modelling of container aerodynamics is greatly simplified, and allowance for effects of turbulence, Reynolds Number, wind tunnel interference and geometry modifications becomes possible.

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Section: Nomenclaturementioning

confidence: 99%

Modelling of static aerodynamics of helicopter underslung loads

Greenwell

2011

Aeronaut. j.

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“…The coupling of the fuselage and load characteristics can induce unstable oscillations in both hover/low-speed and forward flight (Refs. 1,2). Studies have also shown that the presence of large external loads degrades handling qualities during precision maneuvering at low speed (Ref.…”

Section: Introductionmentioning

confidence: 98%

Helicopter Slung Load Control Using Lagged Cable Angle Feedback

Krishnamurthi¹,

Horn²

2015

j am helicopter soc

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A control design method to address stability and handling qualities issues associated with helicopter slung load operations in hover and low speed is presented. A low-order model is developed using first principle physics, with application of basic control techniques. Subsequently, a nonlinear slung load model is developed and integrated with the GENHEL-PSU simulation of the UH-60. Linear model frequency responses are verified against Aeroflightdynamics Directorate (AFDD) OVERCAST models and flight data, showing good correlation in the relevant frequency ranges. A control architecture based on dynamic inversion is developed, combining fuselage and load state feedback. Slung load states are added in feedback linearization, and lagged cable angle feedback is introduced. The controller is shown to reduce load oscillations with trade-offs in pilot response. A controller that uses only lagged cable angle feedback (and no cable state feedback)is also investigated and found to provide good load stabilization without the use of noisy cable angle and rate sensor signals. Sensitivity to parameter variations and optimization methodologies are considered in aiding the design process. Nonlinear batch and real-time simulations are conducted to evaluate performance of the controller.

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“…There is therefore, from helicopter pilots and from the aerospace industry in general, a large interest in technologies that can reduce the challenge in operating helicopter slung loads. Almost all research in this area has been focused on modeling and stability analysis 2,3 . The design of an autonomous Unmanned Aerial Vehicle (UAV) carrying slung loads is rarely seen in the literature.…”

Section: Introductionmentioning

confidence: 99%

Swing Damping for Helicopter Slung Load Systems Using Delayed Feedback

Bisgaard

Cour-Harbo

Bendtsen

2009

AIAA Guidance, Navigation, and Control Conference

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This paper presents the design and verification of a swing reducing controller for helicopter slung load systems using intentional delayed feedback. It is intended for augmenting a trajectory tracking helicopter controller and thereby improving the slung load handing capabilities for autonomous helicopters. The delayed feedback controller is added to actively reduce oscillations of the slung load by improving the damping of the slung load pendulum modes. Furthermore, it is intended for integration with a feedforward control scheme based on input shaping for concurrent avoidance and dampening of swing. The design of the delayed feedback controller is presented as an optimization problem which gives the possibility of an automated design process. Simulations and flight test verifications of the control system on two different autonomous helicopters are presented and it is shown how a significant improvement of oscillation damping can be achieved.

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Dynamics of a helicopter with a sling load

Cited by 16 publications

References 5 publications

Modelling of static aerodynamics of helicopter underslung loads

Modelling of static aerodynamics of helicopter underslung loads

Helicopter Slung Load Control Using Lagged Cable Angle Feedback

Swing Damping for Helicopter Slung Load Systems Using Delayed Feedback

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