MOBILE TERMINAL, SYSTEM AND METHOD

• US 20130211709A1
• Filed: 11/28/2011
• Published: 08/15/2013
• Est. Priority Date: 12/02/2010
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Takahashi, Makoto
• Granted Patent: US 8,965,684 B2
• Time in Patent Office: Days
• US Class Current: 701/417
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01C 21/30 Map- or contour-matching
• CPC Class Codes: G01S 19/40 Correcting position, velocity or attitude
• CPC Class Codes: G08G 1/005 including pedestrian guidance indicator
• CPC Class Codes: G08G 1/096827 where the route is computed onboard

Abstract

The present invention pertains to a mobile terminal having an autonomous navigation function, said mobile terminal comprising: a map application which performs map matching on the current position of the mobile terminal on a route to a destination; a measurement unit which detects the movement of the mobile terminal, and which provides sensor information representing the number of steps and travel direction; a position calculation unit which determines the current position of the mobile terminal; a travel direction correction unit which, when it has been estimated that a user is walking straight by determining whether the amount of change of the user'"'"'s travel direction is within a prescribed range in a prescribed period, corrects the user'"'"'s travel direction according to the orientation of the straight parts when the user is walking straight on the route; and a current position correction unit which, on the basis of the corrected travel direction and the starting time and starting point when walking straight, recalculates the current position of the mobile terminal from the starting point, and corrects the current position of the mobile terminal according to the recalculated current position.

Claims

1. A mobile terminal having an autonomous navigation function, comprising:

a map application unit configured to perform map matching of a current position of the mobile terminal onto a route from a departure point to a destination point of a user of the mobile terminal in map information;

a measurement unit configured to detect movement of the mobile terminal and provide sensor information indicative of a number of steps and a travelling direction of the user;

a position calculation unit configured to determine the current position of the mobile terminal based on the number of steps and the travelling direction of the user in the sensor information;

a travelling direction correction unit configured to estimate whether the user is in a straight walking state by determining whether a change amount of the travelling direction of the user in the sensor information is within a predefined range for a predefined time period, if estimating that the user is in the straight walking state, the travelling direction correction unit correcting the travelling direction of the user with a direction of a straight portion of the route in the straight walking state; and

a current position correction unit configured to recalculate the current position of the mobile terminal from a start point based on the corrected travelling direction as well as a start time point and the start point of the straight walking state and correct the current position of the mobile terminal with the recalculated current position.

2. The mobile terminal as claimed in claim 1, wherein when the current position of the mobile terminal calculated by the position calculation unit deviates from the route by a predefined distance, the map application unit performs the map matching of the current position of the mobile terminal onto the route.

3. The mobile terminal as claimed in claim 2, wherein when it is estimated that the user is in the straight walking state, the travelling direction correction unit calculates a direction between two points map-matched previously onto the straight portion of the route and corrects the travelling direction of the user with the calculated direction.

4. The mobile terminal as claimed in claim 1, wherein the travelling direction correction unit estimates whether the user is in the straight walking state by determining whether a standard deviation of measurement values of the travelling direction of the user for the predefined time period is less than or equal to a predefined threshold.

5. The mobile terminal as claimed in claim 1, wherein the travelling direction correction unit estimates whether the user is in the straight walking state by determining whether a change amount of the travelling direction of the user in the sensor information is within a predefined range for a predefined time period as well as determining whether the user has walked by greater than or equal to a predefined distance for the predefined time period based on the number of steps of the user in the sensor information.

6. The mobile terminal as claimed in claim 1, wherein the current position correction unit recalculates the current position of the mobile terminal from the start point by calculating a movement amount of the mobile terminal from the start time point to a current time point based on the number of steps of the user from the start time point to the current time point and the corrected travelling direction and adding the calculated movement amount to the start point.

7. A system, comprising:

a mobile terminal having an autonomous navigation function; and

a server communicatively connected to the mobile terminal,

the server performing map matching of a current position of the mobile terminal onto a route from a departure point to a destination point of a user of the mobile terminal in map information and indicating the position map-matched onto the route to the mobile terminal,

the mobile terminal comprising;

a measurement unit configured to detect movement of the mobile terminal and provide sensor information indicative of a number of steps and a travelling direction of the user;

a position calculation unit configured to determine the current position of the mobile terminal based on the number of steps and the travelling direction of the user in the sensor information;

a travelling direction correction unit configured to estimate whether the user is in a straight walking state by determining whether a change amount of the travelling direction of the user in the sensor information is within a predefined range for a predefined time period, if estimating that the user is in the straight walking state, the travelling direction correction unit correcting the travelling direction of the user with a direction of a straight portion of the route in the straight walking state indicated from the server; and

a current position correction unit configured to recalculate the current position of the mobile terminal from a start point based on the corrected travelling direction as well as a start time point and the start point of the straight walking state and correct the current position of the mobile terminal with the recalculated current position.

8. A method for use in a mobile terminal having an autonomous navigation function, comprising:

performing map matching of a current position of the mobile terminal onto a route from a departure point to a destination point of a user of the mobile terminal in map information;

detecting movement of the mobile terminal and providing sensor information indicative of a number of steps and a travelling direction of the user;

determining the current position of the mobile terminal based on the number of steps and the travelling direction of the user in the sensor information;

estimating whether the user is in a straight walking state by determining whether a change amount of the travelling direction of the user in the sensor information is within a predefined range for a predefined time period, and if estimating that the user is in the straight walking state, correcting the travelling direction of the user with a direction of a straight portion of the route in the straight walking state; and

recalculating the current position of the mobile terminal from a start point based on the corrected travelling direction as well as a start time point and the start point of the straight walking state and correcting the current position of the mobile terminal with the recalculated current position.