Waypoint navigation

• US 20040193334A1
• Filed: 11/25/2003
• Published: 09/30/2004
• Est. Priority Date: 03/27/2003
• Status: Active Grant

• Current Assignee: Saab AB
• Original Assignee: Saab AB
• Inventors: Adebjork, Peter, Carlsson, Carl-Olof
• Granted Patent: US 7,158,877 B2
• Time in Patent Office: Days
• US Class Current: 701/9
• CPC Class Codes: G05D 1/0022 characterised by the communication link data switching networks in general H04L12/00
• CPC Class Codes: G05D 1/0202 specially adapted to aircraft
• CPC Class Codes: G05D 1/105 specially adapted for unpowered flight, e.g. glider, parachuting, forced landing parachutes per se B64D17/00
• CPC Class Codes: G05D 1/106 Change initiated in response to external conditions, e.g. avoidance of elevated terrain or of no-fly zones

Abstract

The invention relates to remote control of an unmanned aerial vehicle, UAV, (100) from a control station (110) by means of a wireless command link (115). The UAV (100) may be controlled in an autonomous mode wherein it flies according to a primary route (R1, R1′) defined by a first set of predefined waypoints (WP1-WP8, IP). The UAV (100) may also be controlled in a manual mode wherein it flies according to an alternative primary route (R1′) defined in real-time by control commands received via the wireless command link (115). Flight control parameters are monitored in both modes, and in case a major alarm condition occurs, the UAV (100) is controlled to follow an emergency route (R2′) defined by a second set of predefined waypoints (HP1-HP7, TP1-TP9, IP). Particularly, a major alarm condition is activated if an engine failure is detected. Then, the emergency route (R2′) involves flying the UAV (100) to an air space above a termination waypoint (TP9) on the ground at which it is estimated that the vehicle'"'"'s (100) flight may be ended without injuring any personnel or causing uncontrolled material damages.

Claims

1. A method of controlling an unmanned aerial vehicle from a control station by means of a wireless command link, involving:

flight control in an autonomous mode wherein the vehicle flies according to a primary route defined by a first set of predefined waypoints,

flight control in a manual mode wherein the vehicle flies according to a primary route defined by control commands received via the wireless command link, and

functional monitoring of a set of flight control parameters in both the autonomous mode and the manual mode, wherein if, in any of the modes, at least one of the flight control parameters falls outside an acceptable range a major alarm condition is activated, the method involves flying the vehicle according to an emergency route defined by a second set of predefined waypoints, wherein the set of flight control parameters including at least one engine parameter, the method comprising;

activating a major alarm condition with respect to an engine failure in case at least one of the at least one engine parameter decreases below a threshold value, and in such case,

the emergency route involves flying the vehicle to an air space above a termination waypoint on the ground at which it is estimated that the vehicle'"'"'s flight may be ended without injuring any personnel or causing uncontrolled material damages.

2. The method according to claim 1, wherein the set of flight control parameters includes a command link parameter, the method comprising:

activating a minor alarm condition with respect to a command link failure in case the command link is interrupted during a first time interval, and in such case,

initiating a horizontal flight of the vehicle.

3. The method according to claim 2, wherein the method comprises:

activating a major alarm condition with respect to a command link failure in case the command link is interrupted during a second time interval exceeding said first time interval, and in such case,

the emergency route involves flying the vehicle towards a base location on the ground.

4. The method according to claim 3, wherein the vehicle is flown towards the base location involving elevating the vehicle to a predetermined altitude.

5. The method according to claim 2, further comprising:

clearing the minor alarm condition with respect to a command link failure in case the command link returns before expiry of the second time interval, and

returning the flight control of the vehicle to the mode in which the vehicle was controlled before the interruption in the command link.

6. A method according to claim 2, wherein in case of a major alarm condition with respect to a command link failure, the command link remains interrupted during a third time interval exceeding said second time interval, the emergency route involves flying the vehicle to an air space above a termination waypoint on the ground at which it is estimated that the vehicle'"'"'s flight may be ended without injuring any personnel or causing uncontrolled material damages.

7. The method according to claim 6, wherein in case of a major alarm condition with respect to a command link failure, the command link remains interrupted during a fourth time interval exceeding said third time interval, initiating an emergency landing of the vehicle at the termination waypoint.

8. The method according to claim 1, wherein in case the command link returns at any instance in time, a link status message is transmitted from the vehicle to the control station, the link status message indicating a functioning condition for the command link.

9. The method according to claim 8, wherein after transmission of the link status message, the method further comprises:

enabling the vehicle to receive overriding commands from the control station via the command link,

discontinuing a flight according to the emergency route in case overriding commands are received, and in such case

enabling a flight control according to the manual mode.

10. The method according to claim 1, wherein the autonomous flight control mode includes transmission of the control commands to the vehicle in the form of a number of commands constituting an alternative set of waypoints.

11. The method according to claim 1, wherein the manual flight control mode includes transmission of the control commands to the vehicle in the form of real-time commands.

12. The method according to claim 1, further comprising:

selecting points from the first set of predefined waypoints from an indexed table by means of a stepwise procedure, and

selecting points from the second set of predefined waypoints by means of jumping from a first line in the indexed table to a second line in the indexed table, the second line being specified on said first line.

13. A computer program directly loadable into the internal memory of a digital computer, comprising software for accomplishing the steps of claim 1 when said program is run on a computer.

14. A computer readable medium, having a program recorded thereon, where the program is to make a computer accomplish the steps of claim 1.

15. An unmanned aerial vehicle controllable from a control station by means of a wireless command link comprising

an on-board flight control system including:

an autonomous control sub-system adapted to control the vehicle to fly according to a primary route defined by a first set of predefined waypoints, and

a manual control sub-system adapted to receive commands from the control station via the wireless command link, and control the vehicle to fly according to a primary route defined by the commands from the control station, and

a functional monitoring system adapted to monitor a set of flight control parameters, and in case at least one of the flight control parameters falls outside an acceptable range, set a major alarm condition and initiate a flight of the vehicle according to an emergency route defined by a second set of predefined waypoints, wherein the set of flight control parameters includes at least one engine parameter, and the functional monitoring system is adapted to, in case at least one of the at least one engine parameter decreases below a threshold value, set an alarm condition with respect to an engine failure, and fly the vehicle according to the emergency route to an air space above a termination waypoint on the ground at which it is estimated that the vehicle'"'"'s flight may be ended without injuring any personnel or causing uncontrolled material damages.

16. The unmanned aerial vehicle according to claim 15, wherein the functional monitoring system is adapted to monitor the wireless command link, and in case the command link is interrupted during a first time interval:

activate an alarm condition with respect to a minor command link failure, and

initiate a horizontal flight of the vehicle.

17. The unmanned aerial vehicle according to claim 16, wherein the functional monitoring system is adapted to, in case the command link is interrupted during a second time interval exceeding said first time interval:

activate a major alarm condition with respect to a command link failure, and

fly the vehicle towards a base location on the ground.

18. The unmanned aerial vehicle according to claim 16, wherein the functional monitoring system is adapted to, in case the command link returns before expiry of the second time interval:

clear the alarm condition with respect to the minor command link failure, and

return the flight control of the vehicle to the control sub-system which controlled the vehicle before the interruption in the command link.

19. The unmanned aerial vehicle according to claim 17, wherein the functional monitoring system is adapted to, in case of a major alarm condition with respect to a command link failure, the command link remains interrupted during a third time interval exceeding said second time interval, fly the vehicle to an air space above a termination waypoint on the ground at which it is estimated that the vehicle'"'"'s flight may be ended without injuring any personnel or causing uncontrolled material damages.

20. The unmanned aerial vehicle according to claim 17, wherein the functional monitoring system is adapted to initiate a landing of the vehicle at the termination waypoint, if at the expiry of a fourth time interval after that the command link failure occurred, the command link failure remains;

the fourth time interval exceeding said third time interval.

21. The unmanned aerial vehicle according to claim 16, wherein the functional monitoring system is adapted to, in case the command link returns at any instance in time, generate a link status message indicating a functioning condition for the command link.

22. The unmanned aerial vehicle according to claim 21, characterized in that the functional monitoring system is adapted to, after that the link status message has been transmitted to the control station:

enable the vehicle to receive overriding commands from the control station via the command link,

discontinue a flight according to the emergency route in case overriding commands are received, and in such case

enable activation of the manual control sub-system.