FOLLOW-THE-LEADER STATIONKEEPER SYSTEM

• US 3,573,818 A
• Filed: 08/15/1968
• Issued: 04/06/1971
• Est. Priority Date: 08/15/1968
• Status: Expired due to Term

• Current Assignee: Johnson Allen Burdell, Lennon William Tobin Jr, Michnik Lewis
• Original Assignee: Johnson Allen Burdell, Lennon William Tobin Jr, Michnik Lewis
• Inventors: LENNON WILLIAM TOBIN JR, JOHNSON ALLEN BURDELL, MICHNIK LEWIS
• Application Number:
  US04/752,854
• Time in Patent Office: 964 Days
• US Class Current: 342/29
• CPC Class Codes: G01S 11/08 using synchronised clocks
• CPC Class Codes: G05D 1/104 involving a plurality of aircrafts, e.g. formation flying traffic control systems for aircraft G08G5/00

Abstract

A stationkeeping system for maintaining the positions of aircraft operating in a follower mode with respect to other nearby aircraft which may be designated to operate in a leader mode, all aircraft having accurately synchronized time clocks, and the aircraft transmitting pulse groups during their own time slots, marking their positions and also telemetering other encoded data such as altitude and intended maneuvers. Each follower aircraft receives all such transmissions during time slots in which they were transmitted by other aircraft, and selects a particular slot belonging to an aircraft which it chooses to follow. It processes the received data and displays it by a cluster of instruments showing spacing relative to the selected aircraft both in the direction of flight, and transversely thereof, as well as differential altitude and intended maneuvers, such instruments including means for entering offsets defining relative positions which it is desirable for the follower to maintain.

Claims

1. A stationkeeping system for maintaining the positions of aircraft operating in a follower mode with respect to aircraft operating in a leader mode wherein the various aircraft include synchronized clock means establishing time slots occupied thereby, comprising:

a. time slot determining means in each aircraft, including means for selecting its own time slot and means for selecting the time slot of another aircraft chosen as a leader;

b. means in each aircraft for transmitting within its own time slot a ranging signal for marking its own position, and including means for measuring and transmitting an indication of its own altitude;

c. means in a each aircraft for receiving ranging signals and indications of altitudes transmitted by other aircraft;

d. means in each aircraft, when operating in a follower mode and controlled by said means for selecting a leader'"'"''"'"'s time slot, for actuating the receiving means for receiving the leader'"'"''"'"'s altitude indication thereduring, for measuring range and relative bearing to the leader aircraft using the latter'"'"''"'"'s position-marking signal, and for resolving the measured range and bearing into separation components respectively in the direction of flight and transversely thereof; and

e. instrument display means operative in the follower mode to separately display the separation components in the direction of flight and the components transversely thereof with respect to the leader aircraft and indications of the latter'"'"''"'"'s altitude.

2. In a system as set forth in claim 1, said time slot determining means all having means for marking predetermined instants in each time slot, the transmitting aircraft transmitting its ranging signal at one of said instants and transmitting an altitude signal after another of said instants, the time after said another instant indicating altitude;

and the receiving aircraft having a counter having an output for indicating range and altitude of the transmitting aircraft, the system including means to commence the counter counting at said one instant and to cease the counting upon receipt of the ranging signal to provide an output range indication, and having means to commence the counter counting again at a moment which is delayed beyond said another instant by the amount of the range count and to cease the counting upon receipt of said altitude signal to provide an indication of altitude.

3. In a system as set forth in claim 2, means in each receiving aircraft for differencing the altitude indication of the transmitting aircraft from its own measured altitude to provide a differential altitude, and for delivering the latter to said display means.

4. In a system as set fortH in claim 2, means in each transmitting aircraft for commencing its counter counting at said another predetermined instant and for counting it up to a level proportional to the locally measured altitude, and for actuating the local transmitting means upon attainment of said level.

5. In a system as set forth in claim 2, the counter in each transmitting aircraft having a total count and the altitude measuring means delivering a count less than said total, the system including means for presetting the difference therebetween into the counter at said another instant and for then counting the counter back up to full count, and means responsive to said full count for actuating the local transmitting means upon attainment thereof.

6. In a system as set forth in claim 1, said instrument display means comprising analog indicating meters for respectively indicating a separation component along the flight path as measured to a leader aircraft occupying a selected time slot, for indicating a separation component as measured transversely of the flight path to the same aircraft, and for indicating altitude separation with respect to said leader, and said display means including offset means connected to each of said analog means and adjustable to represent desired separations whereby the meters will read center-scale when the desired separations exist.

7. In a system as set forth in claim 6, means for eliminating said offsets whenever a leader slot is selected which is different from the slot for which the offsets are preadjusted.

8. In a system as set forth in claim 1, means in each leader aircraft for indicating intended maneuvers to follower aircraft including means selectable to indicate intended changes in direction and speed and further including means for telemetering a pulse signal whose pulse delay after a fixed instant in a time slot signifies the intention;

and means in each follower aircraft for receiving said signal, for compensating for propagation delay due to the measured range, and for representing in the receiving aircraft a similar pulse delay after a similar fixed instant, and further including means to decode the latter pulse delay and to display the maneuver represented by the delay of the received signal after said similar fixed instant.

9. A stationkeeping system for maintaining the positions of follower aircraft with respect to leader aircraft, comprising:

a. means for measuring range and azimuth from a follower to a leader aircraft;

b. means for resolving measured range and azimuth into relative spacings respectively in the direction of flight and transversely thereof;

c. means for measuring altitudes in the various aircraft, and for telemetering the same therebetween; and

d. means in the follower aircraft for separately displaying said relative spacings in the direction of flight and said relative spacings transversely thereof with respect to the leader aircraft and for displaying altitude relative thereto.

10. In a system as set forth in claim 9, means in the leader aircraft for selecting, encoding and telemetering to the follower aircraft intended maneuvers with regard to direction and speed;

and means in the follower aircraft to receive, decode and display said indicated maneuvers.