Waypoint navigation using exclusion zones

• US 5,646,855 A
• Filed: 07/19/1995
• Issued: 07/08/1997
• Est. Priority Date: 07/19/1995
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Shaw, Christopher, Hills, Stacy J., Jones, Gregory B.
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): WALDER, STEPHEN JOSEPH
• Application Number:
  US08/504,374
• Time in Patent Office: 720 Days
• Field of Search: 364/448, 364/449.1, 364/449.4, 364/449.3, 364/449.2, 364/460, 364/452, 364/462, 364/444.1, 364/444.2, 364/447
• US Class Current: 701/206
• CPC Class Codes: G05D 1/0206 specially adapted to water vehicles

Abstract

A method is provided for navigating a vehicle. Waypoint exclusion zones areefined as circles whose centers are known-position waypoints. The vehicle is steered along a path that is tangential to the "current" waypoint exclusion zone. This path that is maintained until a relative bearing between the vehicle and a center of the current waypoint exclusion zone is at least 90° if the path is left of the center of the current waypoint exclusion zone, and at most -90° if the path is right of the center of the current waypoint exclusion zone. When either of these conditions is met, the vehicle is located along the circle of the current waypoint exclusion zone. The vehicle is then advanced along the circle of the current waypoint exclusion zone until a heading of the vehicle matches a heading of a path that: is tangential to the "next" waypoint exclusion zone. When the heading of the vehicle matches the heading of the path that is tangential to the next waypoint exclusion zone, the next waypoint exclusion zone becomes the current waypoint exclusion zone for carrying out the steering, maintaining and advancing of the vehicle.

Claims

1. A method of navigating a vehicle, comprising the steps of:

providing a plurality of waypoint exclusion zones, each of said plurality of waypoint exclusion zones defined as a circle having a center and a radius, each said center being a known-position waypoint;

providing a predetermined travel plan for the vehicle that identifies an ordered sequence of travel amongst said plurality of waypoint exclusion zones;

determining a turn direction about each of said plurality of waypoint exclusion zones based on said ordered sequence of travel and relative positions between centers of said plurality of waypoint exclusion zones;

steering the vehicle along a path that is tangential to an i-th waypoint exclusion zone of said ordered sequence of travel, said path that is tangential to said i-th waypoint exclusion zone being a path calculated to one of two possible tangents points of said i-th waypoint exclusion zone based on a turn direction determined for said i-th waypoint exclusion zone;

maintaining said path that is tangential to said i-th waypoint exclusion zone until said vehicle is at least at said calculated tangent point of said i-th waypoint exclusion zone, wherein the vehicle is located along said circle of said i-th waypoint exclusion zone; and

advancing the vehicle along said circle of said i-th waypoint exclusion zone until a heading of the vehicle matches a heading of a path that is tangential to an (i+1)-th waypoint exclusion zone in said ordered sequence of travel, said path being tangential to one of two possible tangent points on said (i+1)-th waypoint exclusion zone based on a turn direction calculated for said (i+1)-th waypoint exclusion zone wherein, when said heading of the vehicle matches said heading of said path that is tangential to said (i+1)-th waypoint exclusion zone, said (i+1)-th waypoint exclusion zone becomes said i-th waypoint exclusion zone for carrying out said steps of steering, maintaining and advancing.

2. A method according to claim 1 wherein none of said plurality of waypoint exclusion zones overlap.

3. A method according to claim 1 wherein said step of determining said turn direction about each of said plurality of waypoint exclusion zones comprises the steps of:

providing an absolute coordinate system; and

calculating, for each said i-th waypoint exclusion zone, an angular difference between a bearing from a center of an (i-1)-th waypoint exclusion zone to said center of said (i+1)-th waypoint exclusion zone and said bearing from said center of said (i-1)-th waypoint exclusion zone to said center of said i-th waypoint exclusion zone in terms of said absolute coordinate system, wherein said angular difference is indicative of one of a clockwise or counterclockwise turn direction.

4. A method according to claim 3 wherein said step of steering includes the step of determining said path that is tangential to said i-th waypoint exclusion zone in accordance with the eguation

5. A method according to claim 3 wherein said heading of said path that is tangential to said (i+1)-th waypoint exclusion zone is determined in accordance with the equation

6. A method of navigating a vehicle, comprising the steps of:

providing a plurality of waypoint exclusion zones, each of said plurality of waypoint exclusion zones defined as a circle having a center and a radius, each said center being a known-position waypoint;

providing a predetermined travel plan for the vehicle that identifies an ordered sequence of travel amongst said plurality of waypoint exclusion zones, wherein a current waypoint exclusion zone in said ordered sequence of travel identifies one of said plurality of waypoint exclusion zones to which the vehicle is currently headed, and wherein a next waypoint exclusion zone in said ordered sequence of travel identifies one of said plurality of waypoint exclusion zones to which the vehicle is headed after said current waypoint exclusion zone;

steering the vehicle along a path that is tangential to said current waypoint exclusion zone;

maintaining said path that is tangential to said current waypoint exclusion zone until a relative bearing between the vehicle and a center of said current waypoint exclusion zone is at least 90°

if said path that is tangential to said current waypoint exclusion zone is left of said center of said current waypoint exclusion zone, and at most -90°

if said path that is tangential to said current waypoint exclusion zone is right of said center of said current waypoint exclusion zone, wherein the vehicle is located along said circle of said current waypoint exclusion zone; and

advancing the vehicle along said circle of said current waypoint exclusion zone until a heading of the vehicle matches a heading of a path that is tangential to said next waypoint exclusion zone wherein, when said heading of the vehicle matches said heading of said path that is tangential to said next waypoint exclusion zone, said next waypoint exclusion zone becomes said current waypoint exclusion zone for carrying out said steps of steering, maintaining and advancing.

7. A method according to claim 6 wherein none of said plurality of waypoint exclusion zones overlap.

8. A method according to claim 6 wherein said path that is tangential to said current waypoint exclusion zone is determined in accordance with the equation