Autonomous control of a parafoil recovery system for UAVs

Abstract

A parafoil system for autonomously controlling the gliding descent of a payload/UAV from a launch point to a predetermined recovery area and manipulating the parafoil to execute a soft landing in the recovery area, a sensing means associated with the system for determining wind speed and direction, as well as altitude, heading and position of the system, a means housed within the system for processing information received from the sensing means to determine the gliding flight path from the launch point to a predetermined recovery area and the execution of a flare maneuver to achieve a soft landing, control surface means on the parafoil canopy, mechanical means coupling the information processing means with the control surface means for adjusting the control surface means to accomplish the steering to the recovery area during gliding flight and the flare maneuver during landing, and a power source in the payload/UAV.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an apparatus for the parachute recovery of a payload. More particularly to an autonomous steering of a parafoil recovery system to a recovery area and the soft landing of the payload.

[0003] 2. Description of the Related Art

[0004] Current parachute recovery systems use an uncontrolled round (or ballistic) parachute. The parachute descends at a vertical speed depending on the relation of the size of the parachute to the weight of the payload. The system also has a horizontal speed and direction equal to that of the surface wind. The round parachute system drifts with the wind and impacts the ground at a random orientation. This ground impact usually results in damage to the payload due to the vertical descent rate and the horizontal speed which causes the payload to tumble and/or slam into rocks, trees, etc. In addition, since the round parachute is difficult to steer and drifts with the wind, the ground impact location is random.

[0005] Clearly there is a need for a parachute recovery system that can be steered to a precise recovery area and then execute a soft landing, all autonomously.

[0006] The related art teaches several parachute recovery systems for the controlled steering of the system to a predetermined recovery area, but none include the soft landing offered by the present invention. For example U.S. Pat. No. 5,201,482 to Ream, U.S. Pat. No. 5,620,153 to Ginsberg and U.S. Pat. No. 5,899,415 to Conway all use parafoils (or ram air parachutes) for controlling the glide path of the recovery system. These systems all rely on human piloting of the parafoil (i.e.; non-autonomous). U.S Pat. No. 6,122,572 to Yavnai, teaches an autonomous command and control unit for a powered airborne vehicle that uses a programmable decision unit capable of managing and controlling the execution of a mission by using subsystems and a data base capable of holding and manipulating data including prestored data and data acquired by and received from the various subsystems. U.S. Pat. No. 6,144,899 to Babb et al. discloses a recoverable airborne winged instrument platform for use in predicting and monitoring weather conditions. The platform is taken aloft by balloon mean, accurately determines its present position and uses the data to execute a predetermined flight plan and ultimately guide its descent to a predetermined landing site. This is achieved by installing the instrument package payload in the aerodynamic exterior housing of the recoverable airborne instrument platform.

[0007] Against this background of known technology, the applicant has developed a novel system of components for autonomously managing and controlling a parafoil recovery system to a preselected recovery area and then executing a soft landing.

OBJECTS AND SUMMARY OF THE INVENTION

[0008] It is therefore an object of the present invention to provide a novel system for the autonomous control of the gliding descent of a parafoil recovery system to steer to a predetermined recovery area, while overcoming many of the disadvantages and drawbacks of similar configurations known in the art.

[0009] Another object of the present invention is to autonomously manipulate the parafoil recovery system to execute a soft landing (i.e.; reduce the vertical and horizontal speeds at ground impact relative to an uncontrolled parafoil landing) at the recovery site.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a schematic diagram depicting the parafoil and the attached payload of the present invention;

[0011] FIG. 2 is a schematic diagram depicting the control hardware in the payload of the present invention;

[0012] FIG. 3 is a functional diagram of the control system contained in the payload of the present invention;

[0013] FIG. 4 is a block diagram showing the chronology of functions performed by the autonomous control embodied by the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventor of executing his invention. Various modifications, however will be readily apparent to those skilled in the art, since the generic principles of the present invention have been defined herein specifically to provide a control system for a parafoil that replicates a human operator as the payload, and which encompasses many long sought after features that make the present invention most desirable when used in the parachute recovery of payloads.

[0015] Referring to the schematic diagram of FIG. 1, the parafoil recovery system includes the rectangular shaped, ram-air filled parafoil canopy 12, leading edge 11, railing edge 22 and sides 18 and 18″ of said canopy, the main risers 13 that connect the canopy leading edge and sides to the payload, the brake line risers 14R and 14L that connect the outer portion (left and right) of the trailing edge to the brake reel motors 20R and 20L, the payload 10 (shown here as an unmanned aerial vehicle UAV), and the payload attitude lines 16R and 16L which control the attitude (nose up or nose down) of the payload during descent.

[0016] Referring to FIG. 2 (a schematic diagram of the hardware items in the payload), the parafoil main risers 13 are collected at the parafoil release mechanisms 15R and 15L (releases the payload from the parafoil upon ground impact so that the payload is not dragged across the ground by surface winds) which are connected to the payload attach points 21R and 21L, and the reel motors 20R and 20L which connect to brake line risers 14R and 14L and reel the brake line risers in or out to control the outer portion of the canopy trailing edge.

[0017] FIG. 3 shows a functional diagram of the control system which consists of the IVMC (integrated vehicle management computer) 30, the right and left reel motors 20R and 20L, the GPS antenna 34, the AGL (height above ground level) sensors 35, and the 28 vdc power supply 36. The IVMC contains the motor controller 31, the computer 32, the GPS receiver 33, and the heading indicator (compass) 37.

[0018] FIG. 4 schematically illustrates the step-by-step method by which the control system is executed. The parafoil is deployed from the payload and stabilized in an equilibrium glide in blocks 41 and 42. The main risers are rigged and reel motors are adjusted before launch so that all lines are of the proper length to give this equilibrium glide. In block 43 the location of the recovery system is determined using GPS and a flight plan developed to steer to the stored coordinates of the recovery area. This plan is continually updated to account for winds as the system glides to the recovery area.. When over the recovery area a signal is sent to one reel to adjust the parafoil trailing edge for a spiral flight path in block 44. The spiral flight path permits the computer to determine the wind speed and direction in block 45. The wind direction is needed since the parafoil recovery system always wants to land into the wind in order to reduce the horizontal speed and eliminate the possibility of a sideways or tail first ground impact. In block 46 the computer determines the last spiral and the appropriate time to come out of the spiral for landing into the wind. At 50 feet above ground level the recovery system is prepared for landing by reverting to a very accurate altimeter (±1 foot accuracy). At a TBD altitude AGL a signal is sent to both reel motors in block 50 to reel in the brake lines and apply partial brakes in order to flare the parafoil and reduce the vertical descent speed from ˜27 ft/sec to ˜5 ft/sec. In block 51 the computer determines the ground speed using GPS and determines the extent of the braking (from none to full) to reduce the horizontal speed to 5 ft/sec or less. The payload impacts the ground nose first and slides to a stop.

Claims

1. A system for autonomously controlling the glide path and flare landing of a parafoil recovery system for the recovery of an airborne payload from a launch point to a predetermined recovery area, comprising:

a parafoil canopy coupled to said payload, said parafoil canopy having a flexible leading edge and a flexible trailing edge, said trailing edge having a control surface;

sensing means associated with said system for determining wind speed and direction, as well as altitude, heading and position of said system,

means housed within said payload of the said recovery system for continuously processing information received from said sensing means to determine the glide flight path from the launch point to said recovery area and flare landing maneuver to enable a soft landing, control surface means on said trailing edge of the said recovery system;

mechanical means coupling said information processing means with said control surface means relative to the trailing edge of said parafoil recovery system power source means in said payload,

whereby adjustment of said control surface means is performed on a continuous basis throughout the gliding flight of said recovery system from launch to said recover area.

2. The gliding path and flare maneuver controlling system of claim 1, wherein said mechanical means comprises spool means on said payload and control lines wrapped about said spool means and attached at one end to said trailing edge control surfaces.

3. The gliding path and flare maneuver controlling means of claim 2, and further comprising motors functionally coupled with said processing means and said spool means, for driving said spools in one of a forward winding rotation or a rearward unwinding rotation, whereby as said flight path is determined, adjustments to said control surfaces are made on a continuing basis until the payload impacts the recovery area.

4. The gliding flight path and flare maneuver controlling means of claim 3, wherein said control surfaces comprise said flexible trailing edge of said parafoil canopy.