System and method for route planning under multiple constraints

• US 5,850,617 A
• Filed: 12/30/1996
• Issued: 12/15/1998
• Est. Priority Date: 12/30/1996
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Libby, Vibeke
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US08/777,523
• Time in Patent Office: 715 Days
• Field of Search: 701/200, 701/201, 701/202, 701/209, 701/23, 701/25, 701/117, 701/24, 701/208, 701/120, 701/207, 342/52, 342/55, 342/64, 342/458, 342/451, 342/462, 342/63, 342/29, 342/36, 342/39, 342/455, 340/988-989, 340/990-992, 340/995, 73/178 R
• US Class Current: 701/202
• CPC Class Codes: B64G 1/244 Spacecraft control systems
• CPC Class Codes: B64G 1/36 using sensors, e.g. sun-sensors, horizon sensors

Abstract

A route planning mechanism receives a target set denoting a set of available targets, a set of target parameter thresholds for binning target parameters, a set of mission objectives and a corresponding set of mission thresholds for binning the mission parameters. The route planning mechanism may also receive an avoidance set denoting obstacles to be avoided. The mission objectives define a number of distinct target parameter priority orderings, each associated with a respective mission status. Successive best next targets are selected and added to a selected target sequence list until a mission completion criteria is satisfied. Each best next target is selected by determining a mission status in accordance with the previously selected targets, and a corresponding target parameter priority ordering. The target parameters of each available target are mapped into respective bin values in accordance with their respective target thresholds, and a cost function value is computed for each available target in accordance with the bin values. A subset of the available targets having a best cost function value is selected. That subset is successively narrowed until the subset contains only one target, and then that one target is selected as the best next target. The subset narrowing is performed using the bin values of the target parameters, applied in the target parameter priority ordering that is based on the current mission status. The resulting sequence of selected targets is then passed to a route utilization system, such as a satellite control system.

Claims

1. A route planning method, comprising steps of:

receiving target information concerning a set of available targets, the target information providing a set of target parameters for each of the available targets;

receiving sets of target thresholds, including a set of one or more threshold values for each of at least a subset of the target parameters;

receiving a set of mission objectives defining a plurality of distinct target parameter priority orderings, each target parameter priority ordering being associated with a respective mission status;

selecting a target sequence by repeatedly selecting a best next target and adding the best next target to a selected target sequence list until a mission completion criteria has been satisfied; and

communicating a route, comprising the target sequence, to a route utilization system;

wherein

at a plurality of times while selecting the target sequence, the method includes determining a mission status in accordance with previously selected targets, if any, and determining a target parameter priority ordering in accordance with the determined mission status;

the step of selecting a best next target includes;

for each of at least a first subset of the available targets, mapping a plurality of the target parameters into respective bin values in accordance with respective ones of the sets of target thresholds, and computing a cost function value in accordance with the bin values;

selecting from the first subset of the available targets a second subset having a best cost function value;

if the second subset includes only one target, selecting the one target as the best next target; and

if the second subset includes more than one target, successively narrowing the second subset by removing from the second subset, for successive ones of the target parameters in accordance with the determined target parameter priority ordering, all targets in the second subset except targets having a best bin value for each of the successive target parameters until the second subset contains only one target, and selecting the one target as the best next target.

2. The method of claim 1, further including:

receiving an avoidance set denoting objects that block the route utilization system from visiting various ones of the targets;

the step of selecting a best next target further including;

after selecting the one target, applying the avoidance set to determine if the route utilization system would be prevented from visiting the selected one target, and when the determination is positive, deselecting the one target such that deselected one target is not added to the selected target sequence list.

3. The method of claim 2, the deselecting step including preventing future selection of the deselected one target at least until a best next target has been selected and added to the selected target sequence list.

4. The method of claim 1,

the received set of mission objectives further defining a set of mission resources and corresponding mission resource thresholds for the set of mission resources;

and

the step of determining a mission status including;

determining values for the defined mission resources in accordance with all previously selected targets, if any; and

mapping the mission resources into respective mission resource bin values in accordance with respective ones of the mission resource thresholds, and determining a mission status in accordance with the mission resource bin values.

5. The method of claim 1, further including:

prior to the steps of repeatedly selecting a best next target, determining whether the set of available targets includes a number of available targets that exceeds a predefined maximum number of visitable targets by a predefined margin, and when the determination is positive, deselecting a subset of the available targets that do not meet a predefined high value target criteria so as to prevent consideration and processing of the deselected targets by subsequent steps of the method.

6. The method of claim 1, wherein the mission status determining step updates the determined mission status at predefined intervals, such that the mission status determination is updated less often than a best next target is selected.

7. A route planning method, comprising steps of:

uploading a data set from a control station to a semi-autonomous vehicle, the uploaded data set including;

an initial set of target information, the initial set of uploaded target information providing a set of target parameters for each of the available targets;

sets of target thresholds, including a set of one or more threshold values for each of at least a subset of the target parameters;

a set of mission objectives defining a plurality of distinct target parameter priority orderings, each target parameter priority ordering being associated with a respective mission status;

at the semi-autonomous vehicle, determining a target sequence by repeatedly selecting a best next target and adding the best next target to the selected target sequence list until a mission completion criteria has been satisfied; and

at the control station, independently determining a second, identical target sequence by repeatedly selecting a best next target and adding the best next target to a second selected target sequence list until the mission completion criteria has been satisfied;

uploading updates to the data set from the control station to the semi-autonomous vehicle so as to supplement and/or revise specified portions of the uploaded data set; and

after the updates uploading step;

at the semi-autonomous vehicle, redetermining the target sequence by repeatedly selecting a best next target and adding the best next target to the selected target sequence list until a mission completion criteria has been satisfied; and

at the control station, independently redetermining the second, identical target sequence by repeatedly selecting a best next target and adding the best next target to the second selected target sequence list until the mission completion criteria has been satisfied;

whereby identical target sequences are independently determined by the semi-autonomous vehicle and the control station, and the data set uploaded to the semi-autonomous vehicle is revised without re-uploading the entire updated data set from the control station to the semi-autonomous vehicle.

8. The method of claim 7, each of the target sequence determining steps and each of the target sequence redetermining steps including:

at a plurality of times while selecting the target sequence, determining a mission status in accordance with previously selected targets, if any, and determining a target parameter priority ordering in accordance with the determined mission status;

the step of selecting a best next target including;

for each of at least a first subset of the available targets, mapping a plurality of the target parameters into respective bin values in accordance with respective ones of the sets of target thresholds, and computing a cost function value in accordance with the bin values;

selecting from the first subset of the available targets a second subset having a best cost function value;

if the second subset includes only one target, selecting the one target as the best next target; and

if the second subset includes more than one target, successively narrowing the second subset by removing from the second subset, for successive ones of the target parameters in accordance with the determined target parameter priority ordering, all targets in the second subset except targets having a best bin value for each of the successive target parameters until the second subset contains only one target, and selecting the one target as the best next target.

9. The method of claim 8,

the data set uploading step including uploading from the control station to the semi-autonomous vehicle an avoidance set denoting objects that block a route utilization system from visiting various ones of the targets;

the step of selecting a best next target further including;

after selecting the one target, applying the avoidance set to determine if the route utilization system would be prevented from visiting the selected one target, and when the determination is positive, deselecting the one target such that deselected one target is not added to the selected target sequence list.

10. The method of claim 9, the deselecting step including preventing future selection of the deselected one target at least until a best next target has been selected and added to the selected target sequence list.

11. The method of claim 8,

the set of mission objectives further defining a set of mission resources and corresponding mission resource thresholds for the set of mission resources;

and

the step of determining a mission status including;

determining values for the defined mission resources in accordance with all previously selected targets, if any; and

mapping the mission resources into respective mission resource bin values in accordance with respective ones of the mission resource thresholds, and determining a mission status in accordance with the mission resource bin values.

12. A route planning and utilization system, comprising:

memory for storing a data set, including;

target information, the target information providing a set of target parameters for a set of available targets;

sets of target thresholds, including a set of one or more threshold values for each of at least a subset of the target parameters; and

a set of mission objectives defining a plurality of distinct target parameter priority orderings, each target parameter priority ordering being associated with a respective mission status;

a route planning engine that repeatedly selects a best next target and adds the best next target to a selected target sequence list until a mission completion criteria has been satisfied; and

a route utilization system coupled to the route planning engine, that visits, in order, the targets in the selected target sequence list;

the route planning engine including a data processing unit, and instructions to be executed by the data processing unit, including instructions for;

determining, at a plurality of times while selecting the targets to be added to the selected target sequence list, a mission status in accordance with previously selected targets, if any, and determining a target parameter priority ordering in accordance with the determined mission status;

selecting the best next target by;

for each of at least a first subset of the available targets, mapping a plurality of the target parameters into respective bin values in accordance with respective ones of the sets of target thresholds, and computing a cost function value in accordance with the bin values;

selecting from the first subset of the available targets a second subset having a best cost function value;

if the second subset includes only one target, selecting the one target as the best next target; and

if the second subset includes more than one target, successively narrowing the second subset by removing from the second subset, for successive ones of the target parameters in accordance with the determined target parameter priority ordering, all targets in the second subset except targets having a best bin value for each of the successive target parameters until the second subset contains only one target, and selecting the one target as the best next target.

13. The route planning and utilization system of claim 12,

the data set stored in the memory further including an avoidance set denoting objects that block the route utilization system from visiting various ones of the targets;

the route planning engine including instructions that;

after selecting the one target, apply the avoidance set to determine if the route utilization system would be prevented from visiting the selected one target, and when the determination is positive, deselect the one target such that deselected one target is not added to the selected target sequence list.

14. The route planning and utilization system of claim 13, the route planning engine including instructions that

prevent future selection of the deselected one target at least until a best next target has been selected and added to the selected target sequence list.

15. The route planning and utilization system of claim 12,

the set of mission objectives further defining a set of mission resources and corresponding mission resource thresholds for the set of mission resources;

and

the instructions for determining a mission status including instructions for;

determining values for the defined mission resources in accordance with all previously selected targets, if any; and

mapping the mission resources into respective mission resource bin values in accordance with respective ones of the mission resource thresholds, and determining a mission status in accordance with the mission resource bin values.

16. The route planning and utilization system of claim 12, the route planning engine including instructions for determining, prior to selecting any targets, whether the set of available targets includes a number of available targets that exceeds a predefined maximum number of visitable targets by a predefined margin, and when the determination is positive, deselecting a subset of the available targets that do not meet a predefined high value target criteria so as to prevent consideration and processing of the deselected targets by subsequent steps of the method.

17. The route planning and utilization system of claim 12, wherein the instructions for determining the mission status are executed at predefined intervals, such that the mission status determination is updated less often than a best next target is selected.

18. A route planning and utilization system, comprising:

a semi-autonomous vehicle, including a first wireless communication mechanism;

a control station, including a second wireless communication mechanism that coacts with the first wireless communications mechanism to upload a data set from the control station to the semi-autonomous vehicle, the data set including;

target information, the target information providing a set of target parameters for a set of available targets;

sets of target thresholds, including a set of one or more threshold values for each of at least a subset of the target parameters; and

a set of mission objectives defining a plurality of distinct target parameter priority orderings, each target parameter priority ordering being associated with a respective mission status;

the semi-autonomous vehicle including a first route planning engine that determines a target sequence by repeatedly selecting a best next target and adding the best next target to the selected target sequence list until a mission completion criteria has been satisfied; and

the control station including a second route planning engine that independently determines a second, identical target sequence by repeatedly selecting a best next target and adding the best next target to the second selected target sequence list until the mission completion criteria has been satisfied;

the control station including control mechanisms that, in conjunction with the first and second wireless communication mechanisms, upload updates to the data set from the control station to the semi-autonomous vehicle so as to supplement and/or revise specified portions of the uploaded data set;

the second route planning engine including logic for redetermining the target sequence using the updated data set;

the first route planning engine including logic for redetermining the target sequence, after the updates to the data set have been uploaded to the semi-autonomous vehicle;

whereby identical target sequences are independently determined by the semi-autonomous vehicle and the control station, and the data set uploaded to the semi-autonomous vehicle is revised without re-uploading the entire updated data set from the control station to the semi-autonomous vehicle.