Unmanned aerial vehicle automatic landing system

• US 5,716,032 A
• Filed: 04/22/1996
• Issued: 02/10/1998
• Est. Priority Date: 04/22/1996
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Inventors: McIngvale, Pat H.
• Primary Examiner(s): GRANT, WILLIAM ALEXANDER
• Application Number:
  US08/641,133
• Time in Patent Office: 659 Days
• Field of Search: 244/183, 244/184, 244/185, 244/189, 244/190, 244/186, 244/187, 364/423.099, 364/424.012, 364/428, 342/33
• US Class Current: 244/185
• CPC Class Codes: B64U 2101/30 for imaging, photography or videography
• CPC Class Codes: B64U 2201/20 Remote controls
• CPC Class Codes: B64U 70/95 Means for guiding the landing UAV towards the platform, e.g. lighting means
• CPC Class Codes: G05D 1/0676 specially adapted for landing

Abstract

An automatic landing system for guiding an unmanned aerial vehicle along a predetermined path to a predetermined point on the ground. The system includes an image processing means resident in the motion compensation processor that computes aerial vehicle parameters. The computed parameters are altitude, changes in altitude, changes in pitch and yaw angles, roll angle and changes thereto, and changes in cross range and down range position. These computations are based on the movement of elements in the video of an imaging sensor onboard the aerial vehicle. The motion compensation processor also measures the distance (in pixels or picture elements) between two beacons placed a known distance apart on either side of the apparent touchdown point. A recovery control processor uses these parameters to compute both desired and actual altitude as a function of range from the vehicle to the apparent point of touchdown and to provide offset error in azimuth from the desired flight path to the landing area. The recovery control processor also computes commands for the automatic pilot on the unmanned aerial vehicle which corrects the aerial vehicle'"'"'s flight path. The recovery control processor will normally be located with the motion compensation processor, either on the ground or on the aerial vehicle. The video image can either be brought to the ground over a data link or the image processing can be performed onboard the aerial vehicle.

Claims

1. A landing system for directing a remotely piloted aerial vehicle to a predetermined point in a landing zone comprising:

an autopilot for controlling the flight path of a remotely piloted aerial vehicle;

a data terminal coupled to said autopilot for receiving and sending signals both to and from said autopilot, beacons disposed on the ground adjacent said predetermined point in said landing zone, said beacons consisting of first and second beacons, said first and second beacons being spaced a predetermined distance apart in a plane substantially normal to the plane of the line of sight path from an aerial vehicle imaging sensor when said vehicle is on a desired glide path, said first and second beacons and said predetermined point in the landing zone lying on a common line within said plane, and said first and second beacons generating signals aimed in the direction of said vehicle said imaging sensor being disposed in said aerial vehicle and aligned with the longitudinal axis of said vehicle for generating an image of the landing zone which contains said first and second beacons, said sensor receiving said signals generated by the first and second beacons and including the signals in said image of the landing zone;

a ground based motion compensation processor for calculating actual vehicle flight parameters and for generating output signals corresponding to said calculated parameters; and

a ground based recovery control processor coupled to receive said output signals generated by said motion compensation processor and for comparing said output signals corresponding to the calculated parameters to predetermined flight parameters necessary to land said vehicle at said predetermined point; and

said recovery control processor generating correction output signals for transmission to said autopilot data terminal for adjusting the actual vehicle flight parameters to bring said vehicle to a landing within said landing zone.

2. A landing system for directing a remotely piloted aerial vehicle to a predetermined point in a landing zone as set forth in claim 1, wherein said imaging sensor comprises a television camera and said signals generated by said beacons are detected by said television camera.

3. A landing system for directing a remotely piloted aerial vehicle to a predetermined point in a landing zone as set forth in claim 1, wherein said imaging sensor is an infrared sensor and said first and second beacons generate infrared signals, and said predetermined point in the landing zone is centered between said first and second beacons on said common line.

4. A landing system for directing a remotely piloted aerial vehicle to a predetermined point in a landing zone as set forth in claim 1, wherein said motion compensation processor for calculating actual aerial vehicle flight parameters, generates parameters for altitude, changes in altitude, changes in pitch and yaw angles, roll angle and changes in roll angle, and changes in cross range and down range position, said calculated parameters being based on the movement of elements in the video of said imaging sensor onboard the aerial vehicle, and wherein said autopilot adjusts the actual vehicle flight parameters by reducing engine speed to idle and raising the aerial vehicle nose to an attitude whereby the vehicle begins to stall and the actual altitude begins to decrease independently of any control movement by the autopilot, bringing said vehicle to a landing.

5. A landing system for directing a remotely piloted aerial vehicle to a predetermined point in a landing zone, comprising:

an autopilot for controlling the flight path of a remotely piloted aerial vehicle;

a data terminal coupled to said autopilot for receiving and sending signals both to and from said autopilot;

beacons disposed on the ground adjacent said predetermined point in said landing zone, said beacons consisting of first and second beacons defining a line therebetween, wherein said predetermined point is centered between said beacons on said line, said beacons being spaced a predetermined distance apart in a plane substantially normal to the plane of the line of sight path from an aerial vehicle imaging sensor when said vehicle is on a desired glide path, and said beacons generating signals aimed in the direction of said vehicle;

said imaging sensor being disposed in said aerial vehicle and aligned with the longitudinal axis of said vehicle for generating an image of the landing zone which contains said beacons, said sensor receiving said beacon generated signals and including the signals in said image of the landing zone;

a motion compensation processor for calculating actual vehicle flight parameters, and for generating output signals corresponding to said calculated parameters;

said motion compensation processor taking sequential video images from the imaging sensor, evaluating the movement of individual pixels, and calculating the overall movement of the imaging sensor during the elapsed time between the sequential video images; and

a recovery control processor coupled to receive said output signals generated by said motion compensation processor and for comparing said output signals corresponding to the calculated parameters to predetermined flight parameters necessary to land said vehicle at said predetermined point; and

said recovery control processor generating correction output signals for coupling to said autopilot for adjusting the actual vehicle flight parameters to bring said vehicle to a landing within said landing zone, and wherein said auto adjusts the actual vehicle flight parameters to bring said vehicle to a landing by reducing engine speed to an idle and by stalling the vehicle by raising the nose to an attitude whereby the vehicle altitude begins to decrease independently of any control movement by the autopilot.