SPECIFICATION OF THE INVENTION

1. Title:
A novel system and method for computing the position of member Aircrafts in group air formation flying and providing the computed position of Aircrafts to Map Generator Module for overlay it on digital moving map during the flight and display the same on one of the Cockpit Display System.

2. Field of invention:
The present invention relates to Aircraft navigation, in particular about the computation of Aircrafts position during the flight and providing it to Map Generator Module for overlay on digital moving map during the group air formation flight.

3. Prior art and drawback backs of prior art:
During the formation flight, more than one Aircraft will be involved for accomplishing the mission. Each Aircraft will have predefined flight plan, waypoints and other parameters which will be created using mission planning system and loaded into each Aircraft before the commencement of flight. Hence each Aircraft will follow the flight plan for achieving the mission objectives. In the absence of Communication Link among the participating member Aircrafts, if any of the Pilot in formation wants to have the position of other Aircrafts during the flight, then he has to compute it manually. This increases the additional workload for the Pilot during flight.

4. Aim of Invention
The main objective of this invention is to compute the position of the member Aircrafts during Group Air formation flying. The other objective is to provide the computed position of Aircrafts to Map Generator Module for overlay on digital moving map and display the same on one of the Cockpit Display System.

5. Summary of the invention:
This invention provides system and method to compute the position of the member Aircrafts flying on their respective predetermined flight plans during formation flight and indicate the position of the Aircrafts on Digital Moving Map Display. The "Aircraft Position Computation System" (101) (Refer figure-1) comprises various processing modules such as Mission Plan Database Module (102), Flight Path and Position Computation Module (103) and Data Scheduling Module (104). for data transfer between the "Aircraft Position Computation System" and Cockpit Display System(CDS), Map Generator Module (MGM) & Navigation Sensors.
The Flight Path and Aircraft Position Computation Module (103) receives the own Aircraft position and velocities from onboard Inertial Navigation & Global Positioning System (INGPS), planned mission data (flight plans, Waypoints etc) from Mission Plan Database Module (102). Based on the Mission Plan Data Base and information received from INGPS sensor, it computes the position of own Aircraft and other Aircrafts on their respective flight plans and provides these data to Data Scheduling Module (104). Data Scheduling Module (104) schedules the computed data to Map Generator module periodically for overlay the computed Aircrafts position on digital moving map for display on Cockpit Display System.

6. Brief Description of the Drawings

Figure 1 is a block diagram of the "Aircraft Position Computation System" consists of various processing modules for computation of planned position of Aircrafts in their respective flight plans.

Figure 2 is a Flight path computation for the Waypoints 1,2,3.

Figure 3 is a view of displaying map along with flight plans, planned position of aircrafts and present position of the own Aircraft.

7. Brief description of the invention:
Refer: Figure-1 The "Aircraft Position Computation System" (101) for computing the Aircrafts position in their respective flight plans consists of Mission Plan Database Module (102), Flight Path and Aircraft Position Computation Module (103) and Data Scheduling Module (104). The detailed functionality of each functional block is detailed below. 7.1 Mission Plan Database Module (102) The mission plan data base for each Aircraft of the formation flight is prepared on-ground based on the mission requirement. The database consists of the flight plan for each Aircraft of the formation along with different waypoints and its attributes (Latitude, Longitude, Ground speed). This information is down loaded to non volatile memory of "Aircrafts Position Computation System" before the flight. 7.2 Flight Path and Aircraft Position Computation Module (103) The"Flight Path and Aircraft Position Computation Module"retrieves the flight plan and waypoint's information from the mission plan data base andcompute the flight path based on the geographical position of the waypoints. The figure-2 shows the Flight path in straight and curvature. The flow chart-1 below elaborates the steps involved in the computation of planned position (expected position) of the aircrafts during group air navigation. As per the flight plan for each aircraft, any route between two waypoints is either straight or curved.

As per flight plan described in figure -2, navigation from waypoint 1 to waypoint 2 achieved through straight path. At Step (200),the planned position and estimated time taken for aircrafts in group air navigation during the straight route is computed as mentioned below- T0 = Starting Time of Group Navigation Tc = Current Time of Group Navigation Te = Tc- T0
VCOS0!

Xp — Xt-\ n x Te

, V sin 0i _ I /^Where J

Aj = latitude of waypoint 1 as obtained from flight plan database

^i = longitude of waypoint 1 as obtained from flight plan database

V = Ground speed of aircraft as obtained from flight plan database

Te = Elapsed timeassuming that all the a/c commences their flight at the same time

R = Radius of Earth

61 — Track Angle w. r. t north

The distance between the WPIiA^u-L) and WP2(A2,^2)is computed for estimating the time taken to move from WP1 to WP2 as below-

AfJ = IJ2 - V1

X = cosX 1 sin A ?■ sinXiCosX 2 COSAIJ

Y = COSX2 sin Afj

Z = sin X1 sin X2 + COSAICOSA,2COSAIJ D12 = R*atan2 (tfX2 + Y2], Z)

T-|2est = D12/V

Where-

R = Radius of Earth

Ti2est= estimated time between WP1 and WP2

Again as per flight plan described in figure -2, navigation from waypoint 2 to waypoint 3 achieved through curved path. The planned position during the curved phase of aircrafts in group air navigation computed as mentioned below- At step (201) the turn radiusrturn is computed by the equation

V2 rturn- _gxtan0 Where-

0 = Bank angle

At step (202),distance D between the WP2 {X 2, V 2) and WP3 {X3, y3) is computed as below-

AfJ=fJ3-IJ2

X = cosX 2 sin X 3- sinX2 cosX 3 cos Ay

Y = cosX 3 sin Ay

Z = sin X2 sin X3 + C0SX2 cosX 3 cos Ay

y/=atan2(Y,X)

D = R*atan2 (^X2 + Y2J, Z)

Where-

R = Radius of Earth

At step (203), compare distance 'D' with 2rturn.lf D is less than 2rturn, then perform step (204) assign D to X2 and no curved path can be performed. At step (205), if D>2rturn calculate bearing of the center of turn 'C If the turn is right the bearing of the center 'C is computed as below-Bc= 0! + 90 If the turn is left the bearing of the center 'C is computed as below-

Pc'= di ~ 90

At step (206), based on the radius of turn rturn,bearing Bc(right)and B'c(left), and the coordinates of WP2 (X 2, y 2), latitude and longitude of the center of the curvature(Ac,(ic)right, (Xc,fj!c)left is computed as below-

X = cosX2 cos (rturn /R) - sin X2 sin (rturn / R) cosfic

Y = sin (rturn / R) sinfic

Z = sin X2COS (rturn / R) +cosX2 sin (rturn / R) cosfic Xc = atan2[Z, V(X* + Y2) ] f*c = f*2 + atan2
(Y, X)

Note: For left turn only Bc(right) will change to B'c(left),rest all above computation will remain same. At step (207), bearing 93 (right) ,G'3 (left)and the range X3(right turn),X3'(left turn) of the waypoint WP3 from the center of the curvature 'C is computed for right and left turn as below -

X = cos A, c sin A 3- sin Ac cos A 3 cos Ay

Y = cos A 3 sin Ay

Z = sin Ac sin A3 + cosAc cosA3 cos Ay

03 = atan2 (Y, X)

X3 = R*atan2 (rfX2 + Y2], Z)

Where-

R = Radius of Earth

Note: For left turn onlyAc, \ic(right) will change to A'c, \i'c(left),rest all above computation will remain same. At step (208), X2 is computed, which is the distance between WP3 and end point T of the arc during right turn. For leftturn compute X2' which is the distance between WP3 and end point of the arc in left turn.

X2 = yjX'i — rturn

X2' = V*3'2 - rturn2

Where-

X3' = Distance when turn is left

X2' = Distance when turn is left

At step (209), check if X2 is less than X2', then,at step (210)compute 92 and the arc length for the right turn.

92 - tan x3 Straight leg distance = X2 Arc Angle = 03 + 92- 61 At step (211), if X2 is more than

X2' then compute 02, for left turn.

92 -tan n,

Straight leg distance = X2'

Arc Angle = 2n + 91 + 92 - 63 '

Total time on the straight path T to WP3 (ttp3) during = X2/K(Right turn) Note: For left turn X2 is replaced byX2' Total time on arc-path (tarc_path) = rturn x (Arc Angle) / V At step (212), compute the (AT) uT) from the center of turn C.where AT, uT is the Latitude and Longitude of the point where the arc ends.

Pturn = 90-0!

X = cosAccos (r / R) - sin Ac sin (r / R) cos/?turn

Y = sin (rturn IR) sin /?turn

Z = sin Accos (rturn / R) + cosAc sin (rturn / R) cos&urn AT = Ac +atan2 [ Z, V(X2 + Y2) ] uT= MC
+ atan2 (Y, X)

At step (213),ifTe is less than T12est, then at step 214compute the planned position as per the equation(1). At step (215),if Te is greater than Ti2est and less than sum of T12estand tarc_path,then at step (216), the planned position is on the curved path and is computed using the current arc distance covered as below-

Ppp=(90-B,)-((Tex\/)/rturri)

X = cosAccos (rturn / R) - sin Acsin (rturn / R) cos /?pp

Y = sin (rturn I R) sin /?pp

Z = sin Accos (rturn / R) + cosAc sin (rturn IR) cos /?pp

Ap = Ac +atan2 [ Z, V(X2 + Y2) ]

up = Mc + atan2 (Y, X)

At step (217),if Te is greater than sum of T12estand tarc_path ,then the planned position is on the straight path joining turning point(AT, uT) and WP3 and the position is calculated as below-
*P3=\Je — (T12est + tarcjpath))

X = cos A T sin A. 3- sinZjCOsA.3 cos Ay

Y = cosX 3 sin Ay

Z = sin AT sin A3 + cosXjCOsX 3 cosAfj

/?3 = atan2 (Y, X)

Kcos/? Ap — XT H - x TP3

V sin/? Where TP3=Elapsed time on the straight path joining turning point(AT, UT) and WP3.

The computation of planned position for all the Aircrafts in formation flying is computed and provided to Data Scheduling Module for sending it to Map Generator Module and Cockpit Display System for display. 7.3 Data Scheduling module (104): The present position of the own Aircraft is provided to Map generator module for generating 2 Dimensional Map and the same for displaying on Cockpit Display System. Subsequently the Flight plans information, Aircrafts position information are scheduled to Map Generator Module for generating the Aircrafts position overlay on the Map for displaying in CDS. The Aircrafts position over the map is displayed on CDS (Refer Figure-3).

CLAIMS

We claim

1. An improved system and method, referred as "Aircraft Position Computation System", comprises of "Mission Planning Database Module", "Flight Path and Aircraft Position Computation Module" and "Data Scheduling Module".

2. The "Flight Path and Aircraft Position Computation Module", as claimed in Claim 1 computes the planned position of all the Aircrafts during the flight based on the information received from the "Mission Plan Database Module" and from the Navigation sensors.

3. The "Data Scheduling Module", as claimed in Claim 1, receives the computed position of the member Aircrafts from "Flight Path and Aircraft Position Computation Module" and provide to Map Generator Module for its overlay on Digital moving map for display on Cockpit Display
System.