Tethered vehicle control and tracking system
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsDavid D. North, Mark J. Aull
Life of this patent
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Abstract
A kite system includes a kite and a ground station. The ground station includes a sensor that can be utilized to determine an angular position and velocity of the kite relative to the ground station. A controller utilizes a fuzzy logic control system to autonomously fly the kite. The system may include a ground station having powered winding units that generate power as the lines to the kite are unreeled. The control system may be configured to fly the kite in a crosswind trajectory to increase line tension for power generation. The sensors for determining the position of the kite are preferably ground-based.
Claims12
An autonomously controlled kite system comprising:
- at least one kite that turns based on control. inputs;
- at least one line connected to the at least one kite;
- a base including a line control. mechanism connected to the at least one line, wherein the line control mechanism selectively takes in and lets out the at least one line;
- a sensor configured to determine at least one of a position and a velocity of the at least one kite relative to the base;
- and
- a fuzzy logic control system that categorizes the at least one of the position and the velocity of the at least one kite into at least two sets,
- wherein a degree of membership of the position and/or velocity is given a numerical value signifying membership ranging from no membership to full membership, the control system utilizing one or more rules to generate control inputs that selectively turn the kite to avoid the ground,
- wherein the controller causes the kite to fly in a series of crosswind trajectories and lets out the at least one line while the kite is flying in a crosswind trajectory, and
- wherein the line control mechanism includes a generator that generates power as the at least one line is let out.
A method of autonomously controlling a kite, the method comprising:
- providing at least one steerable kite;
- connecting the kite to a base utilizing at least one line;
- utilizing a camera on the ground to generate images of the at least one kite;
- utilizing the images to determine at least one numerical input value relating to at least one of a position. and a velocity of the at least one kite;
- determining allowable flight positions for the at least one kite;
- and
- utilizing the one numerical input value in a feedback control to produce control outputs that cause the at least one kite to turn and remain within the allowable flight positions,
- wherein the feedback control comprises a fuzzy logic control method that categorizes the numerical input value into at least one fuzzy set,
- wherein a degree of membership in the fuzzy set has a value falling within a predefined numerical range, the value signifying a membership in the fuzzy set ranging from no membership to full membership, and
- wherein the fuzzy logic control method applies rules to the fuzzy set to produce control outputs that cause the kite to turn and remain within ranges of allowable horizontal and vertical positions.
An autonomously controlled kite system comprising:
- at least one kite that turns based on control inputs;
- at least one line connected to the at least one kite;
- a base including a line control mechanism connected to the at least one line, wherein the line control mechanism selectively takes in and lets out the at least one line;
- a sensor configured to determine at least one of a position and a velocity of the at least one kite relative to the base;
- and
- a fuzzy logic control system that categorizes the at least one of the position and the velocity of the at least one kite into at least two sets,
- wherein a degree of membership of the position and/or velocity is given a numerical value signifying membership ranging from no membership to full membership, the control system utilizing one or more rules to generate control inputs that selectively turn the kite to avoid the ground,
- wherein the kite is connected to the line control mechanism by first and second lines, and wherein the line control mechanism includes at least one powered actuator whereby the first and second lines can be selectively taken in under power, and wherein the control inputs comprise shortening one of the first and second lines relative to the other of the first and second lines.
Dependencies are inferred from the claim text.