OUTLINE
Airliner equips two flight instrument for two pilots.
In addition, Standby instrument which called Integrated Standby Flight Display (ISFD) is installed for case of emergency such as loss of main electrical power.
The ISFD indicates Pitch, Roll, Heading, Altitude, Air speed, Vertical speed and Side slip by one display.
However, light weight aircraft usually equips only one instrument and doesn't have standby, so one instrument failure causes serious situation.
Therefore, iPhone based standby instrument called integrated Backup Flight Display (iBFD) is offered.
The iBFD indicates almost same information as ISFD to iPhone's display without additional equipment.
DISPLAY FORMAT
Fig-1 Display Format
PRINCIPLE
1. PITCH, ROLL and YAW ANGLE CALCULATION
(Black portion in Fig-2)
The iBFD calculates pitch, roll and yaw angles using 3 axes gyro sensors of iPhone.
This calculation is the same algorithm as Strapdown Inertial Reference System (IRS) which is installed in actual Airliner and Jet Fighter.
2. GYRO DRIFT ERROR ELIMINATION (Blue portion in Fig-2)
With the above calculation alone, the gyro error is integrated and Pitch and Roll angular error increases with time. This error is called gyro drift.
The IRS uses Schuler tuning with accelerometers to eliminate the gyro drift.
The iBFD uses similar but bit different technics based on this concept.
3. ACCURACY IMPROVEMENT BY GPS (Red portion in Fig-2)
Compared with the actual IRS, the iPhone's gyro sensor has poor accuracy, so even if using the above technic, Pitch and Roll angle accuracy is no sufficient.
Therefore, special technic with GPS data is used to improve Pitch and Roll angle accuracy.
Fig-2 Block Diagram of Calculation
NOTE
NOTE
1. Initial Roll and Pitch Angle
Initial Roll and Pitch angle are calculated by using acceleration at the time of alignment. (Same as actual IRS).
Therefore, if acceleration due to motion is applied during alignment, an angular error will occur.
However, such initial angular error will automatically decreases with time and disappears after within a few minutes in case of level flight.
2. Heading (MS : Magnetic Sensor mode)
The magnetic sensor of iPhone is susceptible to the influence of the surrounding magnetic field. Therefore, if there are magnets nearby, it may not show an accurate value.
3. Heading (GPS : GPS mode)
The initial value of Heading is the value of the magnetic sensor. Therefore, there is a possibility that an error in the initial value for the above reason.
However, if the iPhone moves and the GPS detects the orientation, the error will gradually decrease with time.
4. Engine vibration can affect accuracy of the iBFD, so special consideration must be given to mounting the iPhone to the cockpit instrument panel or glare shield.
5. The iBFD uses GPS in order to indicate velocity and altitude. In addition, GPS is also used to improve Attitude indication accuracy. Therefore, if GPS is not able to be used, the accuracy of Attitude indication will decrease and speed / altitude / vertical speed display will be impossible.
NOTICE
The iBFD doesn’t have enough reliability for use as Primary Flight instruments, and neither our software nor your iPhone have subjected to rigorous certification tests.
All information displayed on the iBFD is for reference only!
Therefore, we are not responsible for any death, injury or damage as a result of using the iBFD.
USE THIS DEVEICE AT YOUR OWN RISK!
integrated Backup Flight Display
