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 comprises: eliminating position possibilities with a heading outside of an expected heading range, the expected heading range including the heading of the roadway on which the position possibility is located plus an angular error region; and eliminating all position possibilities on the same roadway except the position possibility closest to a dead-reckoned position.

Claim 5

The method according to claim 1 further comprising, where no ON ROUTE position possibilities exist, selecting as said current position the OFF ROUTE position possibility most likely to correspond with vehicle position according to criteria selected from the group consisting of proximity to the dead-reckoned position and correspondence of heading at said position possibility with heading of the roadway on which a dead-reckoned position lies.

Claim 6

The method according to claim 4 further comprising assigning the route state of the current position to an OFF ROAD state if no current position has been selected, said OFF ROAD state indicating that no position possibilities corresponding to roadways on said map were received.

Claim 7

The method according to claim 4 wherein the step of determining a route status of said vehicle comprises: comparing the route state of the current position with a stored distance-based route state; increasing a stored distance filter value where the route state of the current position is different than the stored distance-based route state; decreasing the stored distance filter value where the route state of the current position is the same as the stored distance-based route state; comparing the stored distance filter value to a pre-defined threshold value after said increasing or decreasing; setting the stored distance-based route state to the route state of the current position if the stored distance filter value exceeds the threshold value; and assigning the route status the value of the stored distance-based route state.

Claim 8

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 9

The method according to claim 7 further comprising communicating the required maneuver to a user.

Claim 10

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

Claim 11

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

Claim 12

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 13

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; means for filtering the set of position possibilities to remove those least likely to correspond to actual position of the vehicle; means for comparing the position possibilities to positions on said route; means for classifying each position possibility by route state, the route state being selected from the group consisting of ON ROUTE and OFF ROUTE, ON ROUTE being position possibilities corresponding to positions on the route, and OFF ROUTE being position possibilities corresponding to positions not on the route; means for calculating the distance from a first location on said route to each ON ROUTE position possibility; means for selecting a current position, the current position being the ON ROUTE position possibility furthest along the route toward the destination; and means for determining a route status of the vehicle based on said current position.

Claim 14

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; means for filtering the set of position possibilities to remove those least likely to correspond to actual position of the vehicle; means for comparing the position possibilities to positions on said route; means for classifying each position possibility by route state, the route state being selected from the group consisting of ON ROUTE and OFF ROUTE, ON ROUTE being position possibilities corresponding to positions on the route, and OFF ROUTE being position possibilities corresponding to positions not on the route; means for calculating the distance from a first location on said route to each ON ROUTE position possibility; means for selecting a current position, the current position being the ON ROUTE position possibility furthest along the route toward the destination; and means for determining a route status of the vehicle based on said current position.

Claim 15

The route guidance module according to claim 12 wherein said means for verifying comprises means for determining whether said position possibilities are within a selected range of values.

Claim 16

The route guidance module according to claim 12 wherein said means for filtering comprises: means for eliminating position possibilities with a heading outside of an expected heading range, the expected heading range including the heading of the roadway on which the position possibility is located plus an angular error region; and means for eliminating all position possibilities on the same roadway except the position possibility closest to a dead-reckoned position.

Claim 17

The route guidance module according to claim 12 further comprising, where no ON ROUTE position possibilities exist, means for selecting as said current position the OFF ROUTE position possibility most likely to correspond with vehicle position according to criteria selected from the group consisting of proximity to the dead-reckoned position and correspondence of heading at said position possibility with heading of the roadway on which a dead-reckoned position lies.

Claim 18

The route guidance module according to claim 15 further comprising means for assigning the route state of the current position to an OFF ROAD state where no current position has been selected, said OFF ROAD state indicating that no position possibilities corresponding to roadways on said map were received.

Claim 19

The route guidance module according to claim 15 wherein said means for determining a route status of said vehicle comprises: means for comparing the route state of the current position with a stored distance-based route state; means for increasing a stored distance filter value where the route state of the current position is different than the stored distance-based route state; means for decreasing the stored distance filter value where the route state of the current position is the same as the stored distance-based route state; means for comparing the stored distance filter value to a pre-defined threshold value after said increasing or decreasing; means for setting the stored distance-based route state to the route state of the current position if the stored distance filter value exceeds the threshold value; and means for assigning the route status the value of the stored distance-based route state.

Claim 20

The route guidance module according to claim 12 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 21

The route guidance module according to claim 18 further comprising means for communicating the required maneuver to a driver of said vehicle.

Claim 22

The route guidance module according to claim 12 further comprising means for comparing the current position to an intended destination to determine whether arrival has occurred.

Claim 23

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

Claim 24

The route guidance module according to claim 12 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 25

The route guidance module according to claim 12 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.