US 5,276,618 AGranted

Doorway transit navigational referencing system

AssigneeThe United States of America as represented by the Secretary of the Navy

InventorHobart R. Everett, Jr.

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Abstract

A system of navigational referencing for a robot moving within a defined space is provided. A database contains x-y coordinate positional information on a plurality of doorway openings in terms of an x-y coordinate system. A mobile robot is provided that has the capability to access the database, define its location in terms of an approximate position within the defined space, and sense the presence of one of the plurality of doorway openings. The robot is positioned and moved along a path that traverses the one doorway opening at a known speed. The doorway opening's top door frame is detected from first and second sensor positions on the robot. The first and second sensor positions are separated by a known distance along a line orthogonal to the path that traverses the one doorway opening. An angular orientation of the robot is based on a time difference between when the first and second sensor positions detect the top door frame, the known speed of the robot and the known separation distance between the first and second sensor positions. A y-coordinate position of the robot is based on the positional information from the database when the first or second sensing position detects the top door frame. A lateral position of the robot is determined during a portion of the time between when the first and second sensor positions detect the top door frame. The lateral position is compared with the positional information from the database in order to determine an x-coordinate of the robot.

Claims11

Dependent claims

A method of navigational referencing for a robot which moves within a defined space comprising the steps of:

providing the robot with positional information on the defined space in terms of plurality of doorway openings, each doorway opening having left, right and top door frames defining first and second imaginary vertical planes at the beginning and ending, respectively, of each doorway opening, the first and second imaginary vertical planes further being orthogonal to the floor of the defined space, wherein the first and second imaginary vertical planes for each of the plurality of doorway openings are defined in terms of an x-y coordinate system;
finding one of the plurality of doorway openings;
positioning the robot on a heading to traverse said one doorway opening;
moving the robot along a path defined by the heading in order to traverse said one doorway opening at a known speed;
detecting the top door frame from a first sensor position on the robot when the first sensor position enters the first imaginary vertical plane;
detecting the top door frame from a second sensor position on the robot when the second sensor position enters the first imaginary vertical plane, wherein the first and second sensor positions are separated by a known distance along a line orthogonal to the path defined by the robot's heading;
measuring a time difference between when the first and second sensor positions break the first imaginary vertical plane, wherein an angular orientation .alpha. of the robot within the x-y coordinate system is based on the measured time difference, the known speed of the robot and the known separation distance between the first and second sensor positions, and a y-coordinate position of the robot within the x-y coordinate system is based on the provided positional information on the first imaginary vertical plane when the first or second sensing position enters said first imaginary vertical plane;
and
determining a lateral position of the robot with respect to said one doorway opening during a portion of the time between the first sensor position entering the first imaginary vertical plane and the second sensor position entering the second imaginary vertical plane, wherein the lateral position is compared with the provided positional information of said one doorway opening in order to determine an x-coordinate of the robot within the x-y coordinate system.

6 more elements

A system of navigational referencing within a defined space comprising:

a database containing positional information on the defined space in terms of a plurality of doorway openings, each doorway opening having left, right and top door frames defining first and second imaginary vertical planes at the beginning and ending, respectively, of each doorway opening, the first and second imaginary vertical planes further being orthogonal to the floor of the defined space, wherein the first and second imaginary vertical planes for each of the plurality of doorway openings are defined in terms of an x-y coordinate system;
a mobile robot having the capability to access said database, define its location in terms of an approximate position within said x-y coordinate system, and sense the presence of one of said plurality of doorway openings;
means for positioning and moving the robot along a path that traverses said one doorway opening at a known speed;
means for detecting the top door frame from a first and second sensor position on the robot when the first and second sensor positions break the first imaginary vertical plane, wherein the first and second sensor positions are separated by a known distance along a line orthogonal to the path that traverses the one doorway opening, wherein an angular orientation .alpha. of the robot within the x-y coordinate system is based on a time difference between when the first and second sensor positions break the first imaginary vertical plane, the known speed of the robot and the known separation distance between the first and second sensor positions, and a y-coordinate position of the robot within the x-y coordinate system is based on the positional information available from said database on the first imaginary vertical plane when the first or second sensing position enters said first imaginary vertical plane;
and
means for determining a lateral position of the robot with respect to the one doorway opening during a portion of the time between the first sensor position entering the first imaginary vertical plane and the second sensor position entering the second imaginary vertical plane, wherein the lateral position is compared with the positional information from said database on said one doorway opening in order to determine an x-coordinate of the robot within the x-y coordinate system.

3 more elements

Dependencies are inferred from the claim text.