Route guidance on/off-route state filter

Claim 3

The method according to claim 1 wherein said step of verifying comprises determining whether said position possibilities are within a selected range of values.

Claim 4

The method according to claim 1 wherein said step of filtering the first subset comprises: eliminating each position possibility having a heading outside of an expected heading range, the expected heading range including a measured heading of the vehicle plus an angular error region; and eliminating all position possibilities on a first roadway except a closest position possibility, the closest position possibility being closest to a dead-reckoned position.

Claim 5

The method according to claim 1 further comprising the step of determining whether a maneuver of the vehicle is required, the maneuver being selected from the group consisting of left turn, right turn, U-turn, hard left, hard right, easy left, easy right, and combinations thereof.

Claim 6

The method according to claim 4 further comprising communicating the required maneuver to a user.

Claim 7

The method according to claim 1 further comprising comparing the current position to an intended destination to determine whether arrival has occurred.

Claim 8

The method according to claim 1 further comprising communicating the route status to a user.

Claim 9

The method according to claim 1 further comprising: reading a heading sensor and a distance sensor; calculating a dead-reckoned position using heading and distance readings; comparing said dead-reckoned position to said map of roadways; and deriving said position possibilities, wherein said position possibilities comprise positions on said roadways within an error region having said dead-reckoned position as its center.

Claim 10

A route guidance module in a vehicle navigation system for determining whether a vehicle is following a predetermined route on a map of roadways, said route comprising a selected portion of said roadways, said navigation system calculating a dead-reckoned position of said vehicle and further generating a set of position possibilities of said vehicle on said roadways, said route guidance module comprising: means for receiving said set of position possibilities; means for verifying that each of said position possibilities is a valid possibility, thereby generating a first subset of position possibilities; means for filtering the first subset of position possibilities without reference to said predetermined route to remove those least likely to correspond to an actual position of the vehicle, thereby generating a second subset of position possibilities; means for filtering the second subset of position possibilities with reference to said predetermined route, thereby generating a set of remaining position possibilities; means for selecting a current position from the remaining position possibilities; and means for determining a route status of the vehicle based on said current position and said predetermined route.

Claim 11

A route guidance module in a vehicle navigation system for determining whether a vehicle is following a predetermined route on a map of roadways, said route comprising a selected portion of said roadways, said navigation system calculating a dead-reckoned position of said vehicle and further generating a set of position possibilities of said vehicle on said roadways, said route guidance module comprising: means for receiving said set of position possibilities; means for verifying that each of said position possibilities is a valid possibility, thereby generating a first subset of position possibilities; means for filtering the first subset of position possibilities without reference to said predetermined route to remove those least likely to correspond to an actual position of the vehicle, thereby generating a second subset of position possibilities; means for filtering the second subset of position possibilities with reference to said predetermined route, thereby generating a set of remaining position possibilities; means for selecting a current position from the remaining position possibilities; and means for determining a route status of the vehicle based on said current position and said predetermined route.

Claim 12

The route guidance module according to claim 9 wherein said means for verifying comprises means for determining whether said position possibilities are within a selected range of values.

Claim 13

The route guidance module according to claim 9 wherein said means for filtering the first subset comprises: means for eliminating each position possibility having a heading outside of an expected heading range, the expected heading range including a measured heading of the vehicle plus an angular error region; and means for eliminating all position possibilities on a first roadway except a closest position possibility, the closest position possibility being closest to a dead-reckoned position.

Claim 14

The route guidance module according to claim 9 further comprising means for determining whether a maneuver of the vehicle is required, the maneuver being selected from the group consisting of left turn, right turn, U-turn, hard left, hard right, easy left, easy right, and combinations thereof.

Claim 15

The route guidance module according to claim 12 further comprising means for communicating the required maneuver to a driver of said vehicle.

Claim 16

The route guidance module according to claim 9 further comprising means for comparing the current position to an intended destination to determine whether arrival has occurred.

Claim 17

The route guidance module according to claim 9 further comprising means for communicating the route status to a driver of said vehicle.

Claim 18

The route guidance module according to claim 9 wherein said navigation system includes means for switching between at least a first ON ROUTE mode and a second OFF ROUTE mode according to said route status, the route guidance module further comprising means for communicating said route status to said switching means.

Claim 19

The route guidance module according to claim 9 wherein said navigation system comprises: means for reading a heading sensor and a distance sensor; means for calculating said dead-reckoned position using heading and distance readings; means for comparing said dead-reckoned position to said map of roadways; and means for deriving said position possibilities, wherein said position possibilities comprise positions on said roadways within an error region having said dead-reckoned position as its center.

Claim 20

A route guidance system for determining whether a vehicle is following a predetermined route on a map of roadways, said route guidance system comprising: means for storing said map of roadways; means for reading a heading sensor and a distance sensor; means for calculating a dead-reckoned position using heading and distance readings; means for comparing said dead-reckoned position to said map of roadways; means for deriving a set of position possibilities, said position possibilities comprising positions on said roadways within an error region having said dead-reckoned position as its center; means for verifying that each of said position possibilities is a valid possibility, thereby generating a first subset of position possibilities; means for filtering the first subset of position possibilities without reference to said predetermined route to remove those least likely to correspond to actual position of the vehicle, thereby generating a second subset of position possibilities means for filtering the second subset of position possibilities with reference to said predetermined route, thereby generating a set of remaining position possibilities; means for selecting a current position from the remaining position possibilities; means for comparing said current position to said predetermined route to determine a route status of the vehicle, said route status comprising an ON ROUTE status or an OFF ROUTE status; and means for communicating said route status to a user of the route guidance system.

Claim 21

A route guidance system for determining whether a vehicle is following a predetermined route on a map of roadways, said route guidance system comprising: means for storing said map of roadways; means for reading a heading sensor and a distance sensor; means for calculating a dead-reckoned position using heading and distance readings; means for comparing said dead-reckoned position to said map of roadways; means for deriving a set of position possibilities, said position possibilities comprising positions on said roadways within an error region having said dead-reckoned position as its center; means for verifying that each of said position possibilities is a valid possibility, thereby generating a first subset of position possibilities; means for filtering the first subset of position possibilities without reference to said predetermined route to remove those least likely to correspond to actual position of the vehicle, thereby generating a second subset of position possibilities means for filtering the second subset of position possibilities with reference to said predetermined route, thereby generating a set of remaining position possibilities; means for selecting a current position from the remaining position possibilities; means for comparing said current position to said predetermined route to determine a route status of the vehicle, said route status comprising an ON ROUTE status or an OFF ROUTE status; and means for communicating said route status to a user of the route guidance system.