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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

Modeling Helicopter UAV

Carl Thibault

June 30, 2010

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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

Common formulation for helicoptersCommon Assumptions for helicoptersState Formulation

Helicopter Autonomy

The State Space Model

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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

Common Assumptions for Helicopters

1. The earth is at, stationary and therefore an approximateinertial reference frame.

2. The atmosphere is at rest relative to the ground (zero wind)

3. The Rotor head RPM is constant4. The model is only valid in near hover conditions5. The model can not be derived like previous models and must

be identied using experiments.

6. Change in mass during ight is negligible.7. The Yaw rate gyro is still in place as a very fast rate controlon Yaw and there for changes in torque because of controlinput are neglected

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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

State FormulationUsed in AUVs and UAVs the following state space representationis very conventThe UAVs position is expresses relative to an inertial reference.

1 =x

y

z 2 =

= 12 =

x

y

z

Also the vector holds the linear and angular velocity

1 =u

v

w

2 =p

q

r

= 1 2

=

u v

w

p

q

r

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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

Tour of a helicopter

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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

The Rotor head

The Rotor head of helicopterswill usually fall into twocategories the Rigid or Hingedrotor head design full scale

helicopters must use hingedsince the structural strength of the blades is too low to supportits only moment about therotor head.

l f l f h l l h d l

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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

The Coning Angle

As a result of the hinged rotor head or the inherent exibility of theblades the rotating disk will have an angle called the coning angle.This angle acts a little like the dihedral angle in led wing planes

O tli C f l ti f h li t H li t A t Th St t S M d l

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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

The Flapping Angle

The other two signicant angles are the longitudinal and lateralapping angles. The are the result of control input from the swashplate and actuators. The angle tilts the rotor disk and changes thethrust vector relative to the center of gravity allowing translational

motion.

Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

The Swash Plate

The swash plate is what transferscontrol input from the non rotatingbody to the rotating rotor head andybar.

the lower part is actuated by theactuators and is free to move in heightroll and pitch but not yaw as thatwould effect the phase angle where therotor head is actuated.

Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

The Flybar

The ybar is used to dampen the control inputs for model controlsince model scale helicopters have smaller rotor inertial in the manrotor disk this type of aerodynamic gearing allows of unassistedhuman control.

Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

The Full CCPM Rotor Head and Swash Palate

Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

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Outline Common formulation for helicopters Helicopter Autonomy The State Space Model

The Parameterized State-space model

Identied model from the MIT paper used for the assignment

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