Topography-aided guidance system and process

• US 6,279,851 B1
• Filed: 11/22/1989
• Issued: 08/28/2001
• Est. Priority Date: 11/22/1989
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Huss, Ronald E., Vitali, Robert E.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US07/440,969
• Time in Patent Office: 4,297 Days
• Field of Search: 364/424.01, 364/434, 364/436, 364/444, 364/447, 364/462, 364/423, 364/424.02, 342/455, 342/25, 342/26, 342/27, 342/33, 342/36, 342/41, 342/61-65, 342/70, 342/175, 342/189, 342/195, 244/3.15, 244/3.14, 244/3.16-3.19, 356/152-4, 701/301
• US Class Current: 244/3.15
• CPC Class Codes: F41G 7/22 Homing guidance systems

Abstract

In missile guidance systems, knowledge of the target'"'"'s flight policy and doctrine, along with an analysis of local topographic features, are used in a minimum commitment guidance policy. By assuming certain objectives of the target, paths may be defined by evaluating the degree of detection avoidance provided by the terrain adjacent to the various paths. To maximize the probability of intercept, a missile may be guided in a direction covering the most likely of these paths for periods while the target is hidden. The paths are then reevaluated each time the target is detected. For highly maneuverable targets that are capable of executing violent changes in direction and speed, the topography-aided guidance system maximizes the probability that the target can escape the missile intercept envelope. The present invention relates to a topographay-aided missile guidance system that minimzes the probability that an airborne target can escape the missile'"'"'s intercept envelope, where the minimization is over substantially all of the potential actions that the target may take.

Claims

1. A guidance method, comprising the steps of:

determining a plurality of feasible paths, said feasible paths connecting at least one point to at least one destination, said paths being selected based upon the topography adjacent to said paths;

evaluating said feasible paths in relation to desired constraints, said constraints including constraints relating to the topography adjacent to said feasible paths; and

selecting desired responses based upon said evaluation wherein selecting said desired responses comprises the steps of

comparing a present location of an intercept device with at least one target, said target having a variable velocity,

evaluating the probabilities of said intercept device intercepting said target for a plurality of average velocities of said target, along said plurality of feasible paths said target may follow, said evaluations to be applied in a plurality of directions of travel for said intercept device, and

directing said intercept device in a desired direction based upon said evaluations.

2. The method of claim 1 in which evaluating said feasible paths comprises the steps of:

assigning costs to said plurality of paths, said costs relating to the degree by which each path fits;

within said constraints; and

identifying optimal paths between said points and said destinations by comparing said assigned costs of said plurality of paths to identify said optimal paths, said optimal paths comprising at least one path with desired assigned costs.

3. The method of claim 2 in which assigning the costs to a plurality of paths comprises the steps of:

projecting a grid over an area substantially encompassing said point and said plurality of destinations, said grid defining a plurality of potential path segments, said path segments being defined by two endpoints, said endpoints being defined by a pair of nodes on said grid;

calculating said costs related to said constraints for a plurality of path segments in a plurality of directions, said directions being defined by path segments connecting a first node of said pair of nodes to a second node of said pair of nodes; and

storing information relating to said directions and associated costs for said plurality of path segments.

4. The method of claim 3 in which identifying said optimal paths comprises the steps of:

constructing a plurality of paths between said points and said destinations, said paths being defined by a plurality of said path segments;

determining costs for said paths, said costs being the sum of said path segment costs along said path; and

comparing said costs for said paths to identify said optimal paths.

5. The method of claim 1 in which evaluating the probabilities of said intercept device intercepting said target comprises the steps of:

considering a plurality of candidate directions for which said intercept device may travel;

projecting a candidate position for said intercept device for each candidate direction, said candidate position being the projected position of said intercept device having traveled in said candidate direction for a desired time interval;

assigning values based on the likelihood of said intercept device intercepting said target for said target traveling at a plurality of average velocities along a plurality of said feasible paths; and

comparing the values assigned for said plurality of candidate positions to determine said candidate position with the desired value, said candidate position defining a desired direction of travel from said plurality of directions.

6. The method of claim 5 in which assigning values comprises the steps of:

calculating a plurality of range excess values for a candidate position, said range excess values being defined as the difference between the maximum remaining range of the intercept device and the distance to intercept, said range excess values being determined for a plurality of average velocities of said target, presuming said target to travel along one of said plurality of feasible paths;

multiplying said range excess values for said path by desired weight factors relating to the probabilities of said target traveling at each of said average velocities to determine weighted range excess values;

summing said weighted range excess values for said plurality of average velocities to determine a composite range excess value for a desired feasible path for said candidate position;

calculating composite range excess values for each of said feasible paths for said candidate position;

multiplying said composite range excess values by desired weight factors relating to the probabilities of said target traveling along said feasible paths; and

summing said weighted composite range excess values for said plurality of paths to determine a figure of merit to be assigned to said candidate position.