System and method for navigating vehicle along set route of travel

• US 5,371,678 A
• Filed: 11/21/1991
• Issued: 12/06/1994
• Est. Priority Date: 11/22/1990
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Nomura, Takashi
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US07/795,592
• Time in Patent Office: 1,111 Days
• Field of Search: 364/449, 364/444, 364/436, 340/990, 340/995, 340/988
• US Class Current: 701/210
• CPC Class Codes: G01C 21/3492 employing speed data or traffic data, e.g. real-time or historical traffic control systems for road vehicles involving transmission of navigation instructions to the vehicle G08G1/0968
• CPC Class Codes: G08G 1/096827 where the route is computed onboard
• CPC Class Codes: G08G 1/096844 where the complete route is dynamically recomputed based on new data
• CPC Class Codes: G08G 1/096888 where input information is obtained using learning systems, e.g. history databases

Abstract

A system and method for navigating a vehicle along a route of travel are disclosed in which a plurality of routes present between a point of start of the vehicle and a destination are a plurality of road segments divided for respective branching points provided in midways through the plurality of routes of travel are stored in storage areas of a memory in a control unit together with information related to the plurality of road segments. The control unit of the guidance system calculates a predicted time at which the vehicle is to pass through each of the plurality of road segments on the basis of information stored in the storage areas. An optimum route of travel from the starting point to the destination is set according to the result of a calculation of the least predicted time. Hence, even if a traffic limitation time band is provided on the set route of travel due to various types of traffic passage limitations, such an external factor of disturbance is input and stored in the storage areas so that an appropriate route of travel can be searched from the information stored in the storage areas. During the vehicle run on the set route of travel, the appropriate searching for the set route of travel can be made in the midway through the set route of travel according to a presence in a temporary limitation or traffic jam.

Claims

1. A system for determining a route of vehicle travel, comprising:

a) first means having a storage area in which a plurality of routes along which the vehicle can travel from a point of start to a point of destination, said plurality of routes being divided into a plurality of road segments by respective nodes present on said plurality of routes and stored together with a plurality of data representing characteristics inherent to the respective road segments;

b) second means for calculating a predicted time at which the vehicle is to pass through each one of the road segments on a basis of said data on each one of the road segments stored in the first means;

c) third means for setting one of the routes of travel from the point of start to the point of destination according to the result of calculation carried out by said second means,

wherein the data stored in the first means includes coordinate data on positions related to intersections placed at midpoints through the plurality of routes, data related to connections of the intersections to adjacent intersections, distance data on links of road segments between adjacent intersections, data related to angles of the links connected to the intersections, data related to required time for the vehicle to run between the adjacent intersections, and road network including the plurality of links, these data including information on kinds of road segments;

fourth means having a second storage area in which various fixed limitation data including limitation data related to one way traffic area, limitation data related to keep off the traffic, and limitation data related to limited traffic passage are stored together with information on a time duration, hours, and day of a week during which the limitation of traffic passage is carried out and wherein and second means calculates the predicted time duration on the basis of information on each one of the road segments stored in the first means and information stored in the fourth means;

fifth means for inputting thereinto time-varying external data including a traffic limitation information, traffic jam information, traffic accident information, road segment information indicating that at least one of the road segments is under construction;

sixth means for combining the external data with the fixed road map data stored in the first means and/or the fixed limitation data stored in the fourth means, and wherein said second means calculates the predicted time duration on the basis of information on each one of the road segments stored in the first means, traffic limitation data stored in said fourth means, and external data derived from the sixth means;

seventh means having operation blocks through which data on the point of start and destination are input and through which a position of the vehicle is to be displayed and wherein said third means reads data on a region of road segments through which the vehicle is to pass from the point of start according to the data derived from said seventh means and searches the region for an optimum route of travel with the predicted time duration calculated by said second means taken into consideration;

eighth means having a third storage area in which data related to the predicted pass time at which the vehicle is to pass through one of the nodes which is placed on the set route of travel searched by said third means is stored;

ninth means having a geomagnetic sensor for detecting a vehicular direction with respect to a geomagnetic North and a distance sensor for detecting a distance by which the vehicle has run and for calculating an instantaneous position of the vehicle on a two-dimensional coordinate system;

tenth means having a control unit and calendar time and which receives a timer information from the calendar timer, data on the position of the vehicle derived from the ninth means, and data related to the predicted time duration for each node derived from said eighth means, stores data related to a time duration previously scheduled and required to reach to the destination, and detects a change in a running condition of the vehicle by comparing the date related to the time duration previously scheduled with the data related to the predicted time duration for each node stored in said eighth means and wherein said third means sets the optimum route of travel according to the detected change in the running condition of the vehicle of said tenth means; and

eleventh means having a fourth storage area in which changed history data including data related to a changed link, coded data related to a reason for the change and data related to the predicted time duration during which the vehicle is passed through the changed node is stored whenever the searched route of travel set by said third means is changed.

2. A system for determining a route of vehicle travel as set forth in claim 1, which further includes twelfth means having a display unit and which controls the display of the data related to the set route of travel derived from said third means through the display unit, the display unit displaying the set route of travel, the road map related to the region, and vehicular position of the displayed road map.

3. A method for determining a route of vehicle travel, comprising the steps of:

a) setting a point of start of the vehicle and a destination on a regional road map;

b) searching a plurality of routes through which the vehicle is to pass from the point of start to the destination from a storage area in which the plurality of routes and a plurality of road segments created by dividing said plurality of routes by respective nodes present on the plurality of routes are stored together with a plurality of data representing characteristics inherent to the respective road segments;

c) calculating a predicted time at which the vehicle is to pass from one node to another node through each one of the road segments on the basis of said data stored in the storage area;

d) setting an optimum route of travel from the point of start to the destination according to the result of calculation in the step c);

e) determining whether a limitation link on the set route of travel is present, the limitation link providing a limitation data of passage of a traffic;

f) determining whether an external data related to a traffic jam information is input;

g) calculating an actual passage time at which the vehicle is passing through one of the nodes on the midpoint through the set route of travel;

h) deriving an error between the actual passage time and a predicted passage time at which the vehicle is to pass through the corresponding node calculated on the basis of the predicted time duration in the step b) when the limitation link is present;

i) determining whether the error falls in a permissible range;

j) modifying the set route of travel in the step c) when the error does not fall in the permissible range and/or when the external data is input;

k) setting a start intersection toward which the vehicle is first to run from the point of start and setting a time at which the vehicle is passed through the start intersection;

l) initializing a distance from the vehicle start intersection to a plurality of intersections adjacent to the start intersection;

m) calculating distances from the start intersection to the respective adjacent intersections and times required for the vehicle to run from the start intersection to the respective adjacent intersections on the basis of the information related to the adjacent intersections;

n) calculating the predicted time at which the vehicle is to pass through a center intersection, the center intersection being one of the intersections through which the vehicle is to pass along the set route of travel;

o) determining whether the link on which a traffic passage limitation is provided is present at the midpoint from the center intersection to each one of the intersections adjacent to the center intersection;

p) determining whether a predicted time at which the vehicle is to pass through the link on which the traffic passage limitation is provided falls in a time range during which the traffic passage limitation is carried out on the link;

q) determining whether the following inequality is satisfied when determining that the link on which the traffic passage limitation is carried out is not present and/or determining that the predicted time in the step o) does not fall in the time range, L1+L2<

L3, wherein L1 denotes a total distance from the start intersection to the center intersection in a shortest course of route from the start intersection, L2 denotes a distance from the center intersection to each one of the adjacent intersections, and L3 denotes a total distance from the start intersection to each one of the intersections adjacent to the center intersection in the shortest course of route from the start intersection;

r) moving the center intersection to another adjacent intersection through which the vehicle is to pass when determining that the following inequality is not satisfied;

L1+L2<

L3 and/or when determining that the predicted time at which the vehicle is to pass through the link falls in the time range during which the traffic passage limitation is carried out; and

s) repeating the steps from said step o) to the step r) until the center intersection is moved to a final intersection through which the vehicle is finally pass toward the destination.

4. A method for determining a route of vehicle travel as set forth in claim 3, wherein the step m) comprises the steps of:

t) calculating a predicted time at which one of the links through which the vehicle is to pass referring to an average time required for the vehicle to pass through the link on the basis of the fixed road map and fixed limitation data stored in the step b);

u) determining whether the external data related to the traffic jam information is input;

v) converting the time required for the vehicle to pass through the link when determining that the external data related to the traffic jam information is input;

w) modifying the predicted time calculated in the step s) according to a result of conversion in the step u);

x) calculating a time error rate related to a time series and/or to a total distance from the start intersection to the present position; and

y) calculating the predicted time at which the vehicle is to pass through the center intersection.

5. A method for determining a route of vehicle travel as set forth in claim 4, wherein the step o) comprises the steps of:

aa) determining whether the external data through a beacon receiver is input;

bb) converting the external data into an internally processible format of data;

cc) referring to the fixed limitation data stored in the storage area;

dd) referring to the external data added to the fixed limitation data; and

ee) verifying a limitation interval of distance in a direction toward each of the intersections adjacent to the center intersection through which the vehicle is to pass.