design, stability & control, and docking in support of maat project

7/21/2019 Design, Stability & Control, And Docking in Support of MAAT Project

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MAAT – Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1

Design, Stability & Control,and Docking in Support of

MAAT ProjecteDL University of BolognaPier Marzocca Alessandro CerutiCasey Stockbridge

Giorgio Gaviraghi

01.10.2012




2General Descrip t ion

• An MS-Excel tool useful in preliminary design of unconventional airships has been developed by UniBOin collaboration with eDL, iteratively provides design evaluations based on input/output relations

• Inputs: configuration, payload, altitude, cruise speed, guess value for volume• Outputs: volume, subsystems weight, power system features, surface of solar panels needed• The tool embeds data useful to dimension 15 different configurations of unconventional airships;

• Cd and CL obtained by CFD: flow is turbulent, a small change in Cd and Cl due to geometry are expected. Weightand power plant sizing are selected by bibliographical analysis.

• The tools provides useful accurate data for preliminary design considerations, for trade-off design and

sensitivity analysis, and for configurations comparisons.

• One archival publication about this design methodology, under review.

Airship preliminary design and physicalmodeling Tool

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Have been working with several other design and analysis software packages insupport of the MAAT project including Digital DATCOM and an aircraft control toolboxfrom Princeton Satellite Systems.

DATCOM

Supplies information for aerodynamic coefficients, stability derivatives, and dynamic derivatives based ongeometric input and flight conditions.Very flexible for different configurations

PPS Aircraft Control Toolbox

Optimized for traditional ellipsoidal airship geometriesProvides a variety of tools for solar power generation, stability analysis, flight simulations, design,control, etc.

Design and Analysis Tools

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MAAT – Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 01.10.2012

Zeppelin NT

DATCOM



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PPS Aircraft Control Toolbox



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Simulator

AerodynamicData

Wind TunnelExperiments

ControlLaw

FlowVisualization

DockingOperations Mechanism

RapidPrototyping




7General Descrip t ion

• Flight simulator developed by UniBo and eDL – Clarkson University

• The aim of this tool is to provide initial informations about the modelling and dynamics ofthe docking/undocking: informations gathered will be useful for comprehensive analysis ofdocking operation conditions and mechanism design

• Within WP3 UniBO addressed the mathematical model of the airship, while eDL/Clarkson isdeveloping the flight control algorithms for airships approach and docking.

• A simple virtual environment has been implemented to visually evaluate airshipdocking/undocking.

• Currently under testing and initial data will be provided to partners as soon as the simulatorwill be operational for the selected airship model provided by UniMoRe

• Additionals details will be provided in the presentation of eDL-UniBo-Clarkson

Flight Simulator for preliminary designand docking studies

01.10.2012




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Mathemat ical Model

• This is a 6 DOF flight simulator taking into account added masses. Two airships can besimulated simultaneously.

• The model is parametric: the model parameters required for simulations are listed in aninitialization text file, values can be easily edited.

• Based on a series of look-up tables, propulsion or aerodynamics characteristics can bemodified rapidly.

• Implements control surfaces (horizontal, vertical, etc), motors (defined by position, pitch,and thrust).

• Data required: geometry, masses distribution, added masses, aerodynamics, propulsion


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Constants and required data :

• CD look-up table (variable with angle-of-attack (AOA) and sideslip)• CL look-up table (variable with AOA)• Cm look up table (variable with AOA)• Mass distribution of main items (car, envelope, engines, payload)• Position and power of the electric motors

Input :• Throttle, elevator, rudder, propeller pitch, position of the airships (GPS Lat, Long, Alt) both

for cruiser (airship 1) and feeder (airship 2).Outpu t :

• For airship 1 & 2: attitude (pitch, roll, yaw), Lat, Long, Alt, Air Speed, GPS speed, GPScourse, distance between airships


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Simulink Model



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State Extraction

Forces & Moments

Airship Dynamics



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Flight Simulator Virtual Environment




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Control model creates a linearized model from the airship dynamics and uses a state space controlapproach to create a closed loop system.Working with linear-quadratic regulators for feedback control and to optimize the controllers using thecruiser parameters as inputs for the feeder.Control work is currently based on flight simulator model but future work will lead to a robust controlsystem that is not only robust to modeling but also to the physical uncertainties due to flow field loadingor to geometrical and structural parameters.

Flight Control

01.10.2012

InputControls

Feeder Airship

Dynamics

VirtualEnvironment

ControllerCruiser Airship

DynamicsSimplified flow diagram for control loop model




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Design Methodology*

01.10.2012

FEM analysis of the RPmodel under test loads +stinger balance constrain

Wind tunnel testingSTM model structuraldimensioning andmanufacturing

RP model externaldimensions evalutation(wind tunnel blockage,Reynold similarity)

Evaluation of aerodynamicloads on RP model

Evaluation of C L, C D. C Y, C m ,C l, C r for flight simulation

*Being pub l i shed on the Jou rna l o f Rap id P ro to typ ing

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64 5




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Wind Tunnel Testing

Wind tunnel testing to be

performed on the final UniMoRecruiser and feeder models atClarkson University’s wind tunneltest facility.Currently designing and sizing

the test models to minimizeeffects of wall interference andblockage and to optimize testcapabilities.

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The wind tunnel experimental setup will consist of both the cruiser and feeder models.The models can be suspended and subjected to gust loads ahead of them todetermine the best docking approach for the feeder whether it be from the front orrear of the cruiser.The models can also be suspended by spring systems to evaluate the vibrationcharacteristics due to vortex shedding.Flow visualization techniques can be applied to visually identify flow and sheddingover the models using smoke test or special flow visualization paint blends.When the direction of docking and docking operations are identified, aerodynamiccharacteristics of the feeder can be determined where the feeder is to be mounted onthe tunnel’s force balance stinger and the cruiser is mounted on a rail system toadjust the distance between the models either in front or behind.

The forces and moments will be measured on the feeder assuming that interaction betweenthe two models is going to have a greater affect on the feeder due to the significantly largersize of the cruiser and assuming that the cruiser is to remain stable during feeder/cruiserinteraction.

Experimental Setup

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Wind tunnel data will be acquired using a 6 degree of freedom forcebalanceData to be collected in the wind tunnel includes:

Drag, Lift, and Lateral forcesRoll, Yaw, and Pitching momentsMeasurements at various angle of attacks and sideslip angles

Measured data can be used to examine stability coefficientsData collected in wind tunnel can be used in support of use of thesimulator to help construct various data in lookup tables such as the liftand drag coefficients.Wind tunnel testing to be performed during late October, early November

Wind Tunnel Data Acquisition

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6 Component Balance

01.10.2012

Sting Diameter& Designation

NormalForce

SideForce

AxialForce

PitchingMoment

YawingMoment

RollingMoment

(INCHES) (LBS) (LBS) (LBS) (IN LBS) (IN LBS) (IN LBS)1/2 A 40 30 12 70 60 60

1/2 B 60 36 15 120 70 805/8 A 100 75 25 200 156 1505/8 B 150 100 25 250 180 200




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Rapid Prototyping

Wind tunnel prototypes to be built

using rapid prototypingtechnologies at UniBo (left)Rapid prototyping allows for thefabrication of objects directly fromthe CAD models by using

materials such as polymers forconstructionModels are scheduled to be builtduring Sept. 21 – Oct. 3

01.10.2012




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Rapid Prototyping

Similar capabilities for model

construction are available atClarkson University using the testfacility’s stereolithographymachine (right)

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Benefits and Advantages of RP:CostTimeGeometrical ComplexityWeight

Accuracy

Surface FinishSmall Parts and Details Addition of pressure portsMoveable parts

Rapid Prototyping

01.10.2012

Example of aircraft model producedusing rapid prototyping methods andtechnologies




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Docking is a delicate procedure that needs to be performed while thecruiser and feeder are flying in formation.Some considerations for docking:

Pressure equalization between cruiser and feeder connectionsForces and moments applied to docking structures in flightSize of mechanism to ensure passenger comfort and ease of payload transfer

Wind tunnel testing can help define the best approach for dockingprocedures which can be further supported by the simulator.Currently reviewing docking mechanisms which may be adapted ormodified suitable for the requirements of MAAT

Docking

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Docking Mechanisms

01.10.2012

NASA Docking System (NDS)Low impact (in development)

Common Berthing MechanismUsed to connect non-Russian modules on ISS




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With selection of a final configuration rapid prototyping and wind tunneltesting can begin.The empirical and visual results from wind tunnel testing will helpdetermine the best approach to take for docking.Wind tunnel data and the development of a control law can be used tofurther study docking operations

With a final configuration and docking approach a docking mechanismcan be developed.

Conclusions

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Casey StockbridgeGraduate StudentClarkson University, Potsdam, NY, 13699

[email protected]

01.10.2012

Pier Marzocca Associate ProfessorClarkson University, Potsdam, NY, 13699

[email protected]

Alessandro Ceruti Assistant Professor

University of Bologna, [email protected]

Giorgio GaviraghieDL, Montevideo, [email protected]

mailto:[email protected]








design, stability & control, and docking in support of maat project

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