Path planning in an uncertain environment
First Claim
1. Apparatus for controlling an object of known position to follow a path, the apparatus comprisingmeans for storing a representation of a current or future environment of the object, the representation including a configuration space including a plurality of states, each state including a cost to goal value, at least one cost to goal value being based on a probability of a condition occurring in that environment, wherein the existence of the condition is not known with certainty;
- means for planning the path based on the representation; and
means for controlling the object to follow the path.
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Accused Products
Abstract
Configuration spaces, representing alternate possibilities for an environment in which an object is to move, are combined to create a probabilistic representation of all of the alternate possibilities. The probabilistic representation is used to plan optimal motion, with uncertainties being resolved at sensing points.
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Citations
23 Claims
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1. Apparatus for controlling an object of known position to follow a path, the apparatus comprising
means for storing a representation of a current or future environment of the object, the representation including a configuration space including a plurality of states, each state including a cost to goal value, at least one cost to goal value being based on a probability of a condition occurring in that environment, wherein the existence of the condition is not known with certainty; -
means for planning the path based on the representation; and means for controlling the object to follow the path. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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11. The apparatus of claim 10 wherein p is a function of time.
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12. The apparatus of claim 10 wherein p is a function of location.
- 13. The apparatus of claim 9 wherein the combining means, in order to effect the insertion, comprises means for calculating the average value according to the equation
- space="preserve" listing-type="equation">CG(at sensing point);
=CG(pathtail1)·
p(uncertainty present)+CG(pathtail2)·
p(uncertainty absent)+C
where CG is a function calculating cost to goal values;
pathtail1 is a variable representing the path from the sensing point to the goal in the presence of that which causes the uncertainty;
pathtail2 is a variable representing the path from the sensing point to the goal in the absence of that which causes the uncertainty;
p is a function calculating the probability of occurrence of its argument; and
C is a variable representing the cost of sensing presence or absence of the uncertainty. - space="preserve" listing-type="equation">CG(at sensing point);
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14. The apparatus of claim 13 wherein p is a function of time.
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15. The apparatus of claim 13 wherein p is a function of location.
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16. The apparatus of claim 13 wherein C is a function of time.
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17. The apparatus of claim 13 wherein C is a function of location.
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18. The apparatus of claim 1 wherein the means for planning comprises
means for following direction arrow values in the configuration space representation to a state which is either a goal or a sensing point where a corresponding uncertainty can be resolved; -
means for determining whether the point is a goal; means for, if a result of the determining step is negative, sensing presence or absence of that which causes the corresponding uncertainty; and means for replacing the configuration space with a configuration space reflecting current knowledge.
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19. The apparatus of claim 18 further comprising iterating until a goal is reached.
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20. Apparatus for controlling an object of known position to follow a path, the apparatus comprising
means for storing a representation of a current or future environment of the object, in which environment the position of the object is taken as known, which representation includes values based on probabilities of conditions occurring in that environment, wherein the existence of said conditions is not known with certainty; -
means for planning the path based on the representation; and means for controlling the object to follow the path. - View Dependent Claims (21, 22, 23)
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Specification