Spelling suggestions: "subject:"helicopter control systems""
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Open Platform for Limit Protection with Carefree Maneuver ApplicationsJeram, Geoffrey James Joseph 24 November 2004 (has links)
This Open Platform for Limit Protection guides the open design of maneuver limit protection systems in general, and manned, rotorcraft, aerospace applications in particular. The platform uses three stages of limit protection modules: limit cue creation, limit cue arbitration, and control system interface. A common set of limit cue modules provides commands that can include constraints, alerts, transfer functions, and friction. An arbitration module selects the best limit protection cues and distributes them to the most appropriate control path interface. This platform adopts a holistic approach to limit protection whereby it considers all potential interface points, including the pilots visual, aural, and tactile displays; and automatic command restraint shaping for autonomous limit protection.
For each functional module, this thesis guides the control system designer through the design choices and information interfaces among the modules. Limit cue module design choices include type of prediction, prediction mechanism, method of critical control calculation, and type of limit cue. Special consideration is given to the nature of the limit, particularly the level of knowledge about it, and the ramifications for limit protection design, especially with respect to intelligent control methods such as fuzzy inference systems and neural networks.
The Open Platform for Limit Protection reduces the effort required for initial limit protection design by defining a practical structure that still allows considerable design freedom. The platform reduces lifecycle effort through its open engineering systems approach of decoupled, modular design and standardized information interfaces.
Using the Open Platform for Limit Protection, a carefree maneuver system is designed that addresses: main rotor blade stall as a steady-state limit; hub moment as a transient structural limit; and pilot induced oscillation as a controllability limit. The limit cue modules in this system make use of static neural networks, adaptive neural networks, and fuzzy inference systems to predict these limits. Visual (heads up display) and tactile (force-feedback) limit cues are employed. The carefree maneuver system is demonstrated in manned simulation using a General Helicopter (GENHEL) math model of the UH-60 Black Hawk, a projected, 53 degree field of view for the pilot, and a two-axis, active sidestick for cyclic control.
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Rotorcraft trim by a neural model-predictive auto-pilotRiviello, Luca 14 April 2005 (has links)
In this work we investigate the use of state-of-the-art tools for
the regulation of complex, non-linear systems to improve the
methodologies currently applied to trim comprehensive virtual
prototypes of rotors and rotorcrafts.
Among the several methods that have been proposed in the
literature, the auto-pilot approach has the potential to solve
trim problems efficiently even for the large and complex vehicle
models of modern comprehensive finite element-based analysis
codes. In this approach, the trim condition is obtained by
adjusting the controls so as to virtually ``fly' the system to
the final steady (periodic) flight condition. Published
proportional auto-pilots show to work well in many practical
instances. However, they cannot guarantee good performance and
stability in all flight conditions of interest. Limit-cycle
oscillations in control time histories are often observed in
practice because of the non-linear nature of the problem and the
difficulties in enforcing the constant-in-time condition for the
controls.
To address all the above areas of concern, in this research we
propose a new auto-pilot, based on non-linear model-predictive
control (NMPC). The formulation uses a non-linear reference model
of the system augmented with an adaptive neural element, which
identifies and corrects the mismatch between reduced model and
controlled system.
The methodology is tested on the wind-tunnel trim of a rotor
multibody model and compared to an existing implementation of a
classic auto-pilot. The proposed controller shows good performance
without the need of a potentially very expensive tuning phase,
which is required in classical auto-pilots. Moreover,
model-predictive control provides a framework for guaranteeing
stability of the non-linear closed-loop system, so it seems to be
a viable approach for trimming complete rotorcraft comprehensive
models in free-flight.
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Monocular vision assisted autonomous landing of a helicopter on a moving deckSwart, Andre Dewald 03 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The landing phase of any helicopter is the most critical part of the whole flight envelope,
particularly on a moving flight deck. The flight deck is usually located at the stern of the ship,
translating to large heave motions. This thesis focuses on the three fundamental components
required for a successful landing: accurate, relative state-estimation between the helicopter
and the flight deck; a prediction horizon to forecast suitable landing opportunities; and
excellent control to safely unite the helicopter with the flight deck.
A monocular-vision sensor node was developed to provide accurate, relative position and
attitude information of the flight deck. The flight deck is identified by a distinct, geometric
pattern. The relative states are combined with the onboard, kinematic state-estimates of
the helicopter to provide an inertial estimate of the flight deck states. Onboard motion
prediction is executed to forecast a possible safe landing time which is conveyed to the
landing controller.
Camera pose-estimation tests and hardware-in-the-loop simulations proved the system
developed in this thesis viable for flight tests. The practical flight tests confirmed the success
of the monocular-vision sensor node. / AFRIKAANSE OPSOMMING: Die mees kritiese deel van die hele vlug-duurte van ’n helikopter is die landings-fase, veral
op ’n bewegende vlugdek. Die vlugdek is gewoonlik geleë aan die agterstewe-kant van die
skip wat groot afgee bewegings mee bring. Hierdie tesis ondersoek die drie fundamentele
komponente van ’n suksesvolle landing: akkurate, relatiewe toestand-beraming tussen die
helikopter en die vlugdek; ’n vooruitskatting horison om geskikte landings geleenthede te
voorspel; en uitstekended beheer om die helikopter en vlugdek veilig te verenig.
’n Monokulêre-visie sensor-nodus was ontwikkel om akkurate, relatiewe-posisie en oriëntasie
informasie van die vlugdek te verwerf. Die vlugdek is geidentifiseer deur ’n kenmerkende,
geometriese patroon. Die relatiewe toestande word met die aan-boord kinematiese toestandafskatter
van die helikopter gekombineer, om ’n beraming van die inertiale vlugdek-toestande
te verskaf. Aan-boord beweging-vooruitskatting is uitgevoer om moontlike, veilige landingstyd
te voorspel en word teruggevoer na die landingsbeheerder.
Kamera-orientasie afskat-toetse en hardeware-in-die-lus simulasies het die ontwikkelde sisteem
van hierdie tesis lewensvatbaar vir vlug-toetse bewys. Praktiese vlug-toetse het die sukses
van die monokulêre-visie sensor-nodus bevestig.
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Prediction of operational envelope maneuverability effects on rotorcraft designJohnson, Kevin Lee 08 April 2013 (has links)
Military helicopter operations require precise maneuverability characteristics for performance to be determined for the entire helicopter flight envelope. Historically, these maneuverability analyses are combinatorial in nature and involve human-interaction, which hinders their integration into conceptual design. A model formulation that includes the necessary quantitative measures and captures the impact of changing requirements real-time is presented. The formulation is shown to offer a more conservative estimate of maneuverability than traditional energy-based formulations through quantitative analysis of a typical pop-up maneuver. Although the control system design is not directly integrated, two control constraint measures are deemed essential in this work: control deflection rate and trajectory divergence rate. Both of these measures are general enough to be applied to any control architecture, while at the same time enable quantitative trades that relate overall vehicle maneuverability to control system requirements. The dimensionality issues stemming from the immense maneuver space are mitigated through systematic development of a maneuver taxonomy that enables the operational envelope to be decomposed into a minimal set of fundamental maneuvers. The taxonomy approach is applied to a helicopter canonical example that requires maneuverability and design to be assessed simultaneously. The end result is a methodology that enables the impact of design choices on maneuverability to be assessed for the entire helicopter operational envelope, while enabling constraints from control system design to be assessed real-time.
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Adaptive Envelope Protection Methods for AircraftUnnikrishnan, Suraj 19 May 2006 (has links)
Carefree handling refers to the ability of a pilot to operate an aircraft without the need to continuously monitor aircraft operating limits. At the heart of all carefree handling or maneuvering systems, also referred to as envelope protection systems, are algorithms and methods for predicting future limit violations. Recently, envelope protection methods that have gained more acceptance, translate limit proximity information to its equivalent in the control channel. Envelope protection algorithms either use very small prediction horizon or are static methods with no capability to adapt to changes in system configurations. Adaptive approaches maximizing prediction horizon such as dynamic trim, are only applicable to steady-state-response critical limit parameters. In this thesis, a new adaptive envelope protection method is developed that is applicable to steady-state and transient response critical limit parameters. The approach is based upon devising the most aggressive optimal control profile to the limit boundary and using it to compute control limits. Pilot-in-the-loop evaluations of the proposed approach are conducted at the Georgia Tech Carefree Maneuver lab for transient longitudinal hub moment limit protection. Carefree maneuvering is the dual of carefree handling in the realm of autonomous Uninhabited Aerial Vehicles (UAVs). Designing a flight control system to fully and effectively utilize the operational flight envelope is very difficult. With the increasing role and demands for extreme maneuverability there is a need for developing envelope protection methods for autonomous UAVs. In this thesis, a full-authority automatic envelope protection method is proposed for limit protection in UAVs. The approach uses adaptive estimate of limit parameter dynamics and finite-time horizon predictions to detect impending limit boundary violations. Limit violations are prevented by treating the limit boundary as an obstacle and by correcting nominal control/command inputs to track a limit parameter safe-response profile near the limit boundary. The method is evaluated using software-in-the-loop and flight evaluations on the Georgia Tech unmanned rotorcraft platform- GTMax. The thesis also develops and evaluates an extension for calculating control margins based on restricting limit parameter response aggressiveness near the limit boundary.
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