DMU380SA Series
User’s Manual
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Doc# 7430-0026 Rev.01
Page 43
Rotorcraft
5.3
Rotorcraft is a category of heavier-than-air flying machines that use lift generated by
rotors. They may also include the use of static lifting surfaces, but the primary
distinguishing feature being lift provided by rotating lift structures. Rotorcraft includes
helicopters, autogyros, gyrodynes and tiltrotors.
The rotor blade dynamics itself is much faster than that of the fixed wing aircraft and
contains high frequency components. At the same time, however, it may cause severe
vibrations on the airframe. Also, the overall dynamics (translational and rotational
motion) of the rotor craft is much slower than the fixed wing aircraft due to a mechanical
mechanism of rotors generating the aerodynamic forces and moments. Table 17 provides
the recommended advanced settings for two different dynamic conditions.
Table 17.
Recommended Advanced Settings for Rotorcraft
Recommended Product
AHRS380SA or INS380SA
Recommended Settings
Dynamic Condition
Normal Dynamics
High Dynamics
(with uncoordinated tail motion)
UseMags
ON
ON
UseGPS
ON
ON (< 4g)
FreelyIntegrate
OFF
OFF (< 2g)
Stationary Yaw Lock
OFF
OFF
Restart Over Range
OFF
ON
Dynamic Motion
ON
ON
Turn Switch Threshold
1.0 deg/s §
30.0 deg/s §
XY Filter Accel
5 Hz*
5 Hz
Z Filter Accel
5 Hz*
5 Hz
Filter Rate Sensor
20 Hz*
20 Hz
§The helicopter can change its heading angle rapidly unlike the aircraft
which requires banking. A turn switch threshold that is too low may cause
turn switch activation with high duty cycle causing random walk in roll and
pitch angles due to low feedback gains.
*A cutoff frequency must be far away from major frequency components
caused by the rotor vibration.
Land Vehicle
5.4
Some examples of land vehicles are: Automobiles, trucks, heavy equipment, trains,
snowmobiles, and other tracked vehicles. Table 18 provides the recommended advanced
settings for two different types of application.