Navigation Device And Current-Position-Calculation Method

A navigation device for a motor vehicle that calculates a current position, the navigation device comprising:

• a map-data-storage unit storing map data defining a map including a road by using at least one link which is a line;
• a vehicle-speed-measuring unit to measure a speed of the motor vehicle;
• an angular-velocity-measuring unit to measure an angular velocity of a change in a travel azimuth of the motor vehicle;
• and
• a current-position-calculation unit to calculate the current position of the motor vehicle,
• wherein the current-position-calculation unit includes:
• a curvature-estimation unit to estimate a road curvature at a first point on a road, the first point corresponding to a second point on the link, as a corresponding curvature of the second point on the link on the basis of the map data stored in the map-data-storage unit, where the corresponding curvature is estimated for each of a plurality of the second points on the link indicating a road on which the motor vehicle is traveling, the road including the current position that was previously calculated;
• an end-point-corresponding-position-calculation unit to calculate a third point that is on the link and that corresponds to an end point of the road-curve section where the orientation of the actual road changes as a curve-section-end-point-corresponding position, on the basis of the estimated corresponding curvature of each of the plurality of second points on the link;
• and
• a current-position-estimation unit to detect that the motor vehicle leaves the road-curve section when a first change occurs in a curvature of a travel locus of the motor vehicle, the travel locus being calculated on the basis of a progress of the measured vehicle speed and angular velocity, where the first change matches with a second change in the corresponding curvature, the second change being caused when the motor vehicle travels on the link from a first section that is on the link and that corresponds to the road-curve section, passes the curve-section-end-point-corresponding position, and leaves the first section, and that is configured to estimate the calculated curve-section-end-point-corresponding position as the current position when it is detected that the motor vehicle leaves the road-curve section.

A navigation device for a motor vehicle that calculates a current position, the navigation device comprising:

• a map-data-storage unit storing map data defining a map including a road by using at least one link which is a line;
• an angular-velocity-measuring unit to measure an angular velocity of a change in a travel azimuth of the motor vehicle;
• and
• a current-position-calculation unit to calculate the current position of the motor vehicle,
• wherein the current-position-calculation unit includes:
• a corresponding-azimuth-angle-estimation unit configured to estimate an azimuth angle of a road orientation at a first point on a road, the first point corresponding to a second point on the link as a corresponding-azimuth angle of the second point on the link, on the basis of the stored map data, where the corresponding-azimuth angle is estimated for each of the plurality of second points on the link indicating the road on which the motor vehicle is traveling, the road including the current position that was previously calculated;
• and
• a current-position-estimation unit configured to calculate an azimuth angle in a travel direction of the motor vehicle as a travel-azimuth angle, on the basis of a progress of the measured angular velocity, and estimate a third point on the link as the current position, where the estimated corresponding azimuth angle agrees with the calculated travel-azimuth angle at the third point.

A current-position-calculation method to calculate a current position by using a navigation device storing map data defining a map including a road by using at least one link which is a line, the current-position-calculation method comprising:

• measuring a speed of the motor vehicle and an angular velocity of a change in a travel azimuth of the motor vehicle;
• estimating a road curvature at a first point on a road, the first point corresponding to a second point on the link, as a corresponding curvature of the second point on the link on the basis of the map data, where the corresponding curvature is estimated for each of a plurality of the second points on the link indicating a road on which the motor vehicle is traveling, the road including the current position that was previously calculated;
• calculating the second point corresponding to a start point of a road-curve section where an orientation of the road changes, as a curve-section-start-point-corresponding position, on the basis of the estimated corresponding curvature of each of the plurality of second points on the link;
• and
• detecting that the motor vehicle enters the road-curve section when a first change occurs in a curvature of a travel locus of the motor vehicle, the travel locus being calculated on the basis of a progress of the measured vehicle speed and angular velocity, where the first change matches with a second change in the corresponding curvature, the second change being caused when the motor vehicle travels on the link from outside a first section that is on the link and that corresponds to the road-curve section, passes the curve-section-start-point-corresponding position, and enters the first section, and calculating the curve-section-start-point-corresponding position as the current position, when it is detected that the motor vehicle enters the road-curve section.

A current-position-calculation method to calculate a current position by using a navigation device storing map data defining a map including a road by using at least one link which is a line, the current-position-calculation method comprising:

• measuring a speed of the motor vehicle and an angular velocity of a change in a travel azimuth of the motor vehicle;
• estimating a road curvature at a first point on a road, the first point corresponding to a second point on the link, as a corresponding curvature of the second point on the link on the basis of the map data, where the corresponding curvature is estimated for each of a plurality of the second points on the link indicating a road on which the motor vehicle is traveling, the road including the current position that was previously calculated;
• calculating a third point that is on the link and that corresponds to an end point of a road-curve section where an orientation of the road changes as a curve-section-end-point-corresponding position, on the basis of the estimated corresponding curvature of each of the plurality of second points on the link,
• detecting that the motor vehicle leaves the road-curve section when a first change occurs in a curvature of a travel locus of the motor vehicle, the travel locus being calculated on the basis of a progress of the measured vehicle speed and angular velocity, where the first change matches with a second change in the corresponding curvature, the second change being caused when the motor vehicle travels on the link from a first section that is on the link and that corresponds to the road-curve section, passes the curve-section-end-point-corresponding position, and leaves the first section, and calculating the curve-section-end-point-corresponding position as the current position when it is detected that the motor vehicle leaves the road-curve section.

A current-position-calculation method to calculate a current position by using a navigation device storing map data defining a map including a road by using at least one link which is a line, the current-position-calculation method comprising:

• a first step of measuring an angular velocity of a change in a travel azimuth of the motor vehicle;
• a second step of estimating an azimuth angle of a road orientation at a first point on a road, the first point corresponding to a second point on the link, as a corresponding-azimuth angle of the second point on the link on the basis of the map data, where the corresponding-azimuth angle is estimated for each of a plurality of the second points on the link indicating a road on which the motor vehicle is traveling, the road including the current position that was previously calculated;
• and
• a third step of calculating an azimuth angle in a travel direction of the motor vehicle as a travel-azimuth angle on the basis of a progress of the measured angular velocity, and calculating a third point on the link as the current position, where the estimated corresponding-azimuth angle agrees with the calculated travel-azimuth angle at the third point.

A computer program which is read and executed by an electronic calculator mounted on a motor vehicle, the computer program making the electronic calculator perform the steps of:

• measuring a speed of the motor vehicle and an angular velocity of a change in a travel azimuth of the motor vehicle;
• estimating a road curvature at a first point on a road, the first point corresponding to a second point on at least one link which is a line, as a corresponding curvature of the second point on the link on the basis of map data defining a map including a road by using the link, where the corresponding curvature is estimated for each of a plurality of the second points on the link indicating a road on which the motor vehicle is traveling, the road including the current position that was previously calculated;
• calculating the second point corresponding to a start point of a road-curve section where an orientation of the actual road changes as a curve-section-start-point-corresponding position, on the basis of the estimated corresponding curvature of each of the plurality of second points on the link;
• and
• detecting that the motor vehicle enters the road-curve section when a first change occurs in a curvature of a travel locus of the motor vehicle, the travel locus being calculated on the basis of a progress of the measured vehicle speed and angular velocity, where the first change matches with a second change in the corresponding curvature, the second change being caused when the motor vehicle travels on the link from outside a first section that is on the link and that corresponds to the road-curve section, passes the curve-section-start-point-corresponding position, and enters the first section, and calculating the curve-section-start-point-corresponding position as the current position when it is detected that the motor vehicle enters the road-curve section.

A computer program which is read and executed by an electronic calculator mounted on a motor vehicle, the computer program making the electronic calculator perform the steps of:

• acquiring a speed of the motor vehicle and an angular velocity of a change in a travel azimuth of the motor vehicle;
• estimating a road curvature at a first point on a road, the first point corresponding to a second point on at least one link which is a line, as a corresponding curvature of the second point on the link on the basis of map data defining a map including a road by using the link, where the corresponding curvature is estimated for each of a plurality of the second points on the link indicating a road on which the motor vehicle is traveling, the road including the current position that was previously calculated;
• calculating a third point that is on the link and that corresponds to an end point of a road-curve section where an orientation of the road changes as a curve-section-end-point-corresponding position on the basis of the estimated corresponding curvature of each of the plurality of second points on the link,
• detecting that the motor vehicle leaves the road-curve section when a first change occurs in a curvature of a travel locus of the motor vehicle, the travel locus being calculated on the basis of a progress of the acquired vehicle speed and angular velocity, where the first change matches with a second change in the corresponding curvature, the second change being caused when the motor vehicle travels on the link from a first section that is on the link and that corresponds to the road-curve section, passes the curve-section-end-point-corresponding position, and leaves the first section, and calculating the curve-section-end-point-corresponding position as the current position when it is detected that the motor vehicle leaves the road-curve section.

A computer program which is read and executed by an electronic calculator mounted on a motor vehicle, the computer program making the electronic calculator perform:

• a first step of acquiring an angular velocity of a change in a travel azimuth of the motor vehicle;
• a second step of estimating an azimuth angle of a road orientation at a first point on a road, the first point corresponding to a second point on at least one link which is a line, as a corresponding-azimuth angle of the second point on the link, on the basis of map data defining a map including a road by using the link, where the corresponding-azimuth angle is estimated for each of a plurality of the second points on the link indicating a road on which the motor vehicle is traveling, the road including the current position that was previously calculated;
• and
• a third step of calculating an azimuth angle in a travel direction of the motor vehicle as a travel-azimuth angle on the basis of a progress of the acquired angular velocity, and calculating a third point on the link as the current position where the estimated corresponding-azimuth angle agrees with the calculated travel-azimuth angle at the third point.