Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
2000-08-04
2001-10-02
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S079000, C701S208000, C340S995190
Reexamination Certificate
active
06298296
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a curve approach control apparatus which controls a vehicle to make it travel a curved road at an appropriate speed.
2. Description of the Related Art
Many curve approach control apparatus have been proposed which use road map data in a navigation device to detect an overspeed state of a vehicle with respect to a curve in front and activate an alarm or deceleration control. For example, Japanese Patent Unexamined Publication No. Hei. 4-236699 (JP-A-4-236699) discloses a technology which determines an appropriate approach speed at which to enter the curve based on a radius of curvature of a curve in an optimum travel path (guided path) set in the navigation device and on detected road surface conditions and, when an actual vehicle(car) speed is higher than the calculated value of the appropriate approach speed, issues a warning to alert the driver to the need for reducing the vehicle speed, or automatically activates a vehicle speed reduction means in combination with the warning.
A method of determining a curve's radius of curvature by using road map data in the navigation device is disclosed, for example, in Japanese Patent Unexamined Publication No. Hei. 11-2528(JP-A-11-2528) filed by the applicant of this invention which describes a technology for determining the curve's radius of curvature from nodes on the road map data of the navigation device.
As shown in
FIGS. 10A and 10B
, it is often the case that in expressways or wide highways (hereinafter referred to as “main roads”) there is a large space at a branch point or merge point leading to an entrance road or exit road to and from the main road. Hence, when a driver moves into or out of the main road, he or she generally utilizes the wide space near the branch or merge point to perform as small a cornering operation as possible.
Nodes on a road map in a navigation device are simply plotted near the center of the road, so that a locus of the nodes plotted on the entrance/exit road to/from the main road apparently represents a significantly tighter curve than the actual locus of the vehicle moving into or out of the main road.
Hence, when the vehicle(car) moves into or out of the main road, if a radius of curvature of the curve is determined based on the node data supplied from the navigation device and, based on the curve's radius of curvature, the alarm control and the deceleration control are performed, these controls may become excessive because they are intended for an apparently sharp curve.
SUMMARY OF THE INVENTION
The present invention has been accomplished under these circumstances and provides a curve approach control apparatus which can reduce unwanted alarms and decelerations that will make the driver feel incongruous when the driver moves into or out of expressways and wide highways.
To solve the problem described above, a curve approach control apparatus according to a first aspect of the present invention comprises: a front road attribute calculation/storage means to set a variety of road attribute information for each node on the basis of at least node information representing a road of vehicle travel path and supplied from a navigation device; an allowable approach speed setting means to determine a curve of the travel path based on at least the road attribute information and set an allowable approach speed for the curve that a vehicle can tolerate; and a decision output means to compare the allowable approach speed with a vehicle speed in a predetermined manner and permit an alarm control or a deceleration control for the curve to be executed; wherein a control execution decision means is provided which inhibits the alarm control and the deceleration control when the curve is on an exit/entrance road connecting to a main road.
A curve approach control apparatus according to a second aspect of the present invention comprises: a front road attribute calculation/storage means to set a variety of road attribute information for each node on the basis of at least node information representing a road of vehicle travel path and supplied from a navigation device; an allowable approach speed setting means to determine a curve of the travel path based on at least the road attribute information and set an allowable approach speed for the curve that a vehicle can tolerate; and a decision output means to compare the allowable approach speed with a vehicle speed in a predetermined manner and permit an alarm control or a deceleration control for the curve to be executed; wherein when the node represents an exit/entrance road connecting to a main road, the allowable approach speed for the node is set higher than allowable approach speeds for other nodes.
In a curve approach control apparatus of a third aspect of the present invention according to the first or second aspect, the n ode information supplied from the navigation device has at least road kind information and road width information on the road made up of nodes and intersection information indicating whether an intersection exists at each node position, and the front road attribute calculation/storage means judges whether the road represented by the node is the main road based on the road kind information and the road width information and, if so, judges whether an intersection exists on the main road based on the intersection information, and, when an intersection exists on the main road and node intervals for the nodes following the intersection are and continue to be less than a predetermined multiple of the road width of the main road, the front road attribute calculation/storage means sets a road segment following the intersection as an exit road from the main road.
In a curve approach control apparatus of a fourth aspect of the present invention according to the first or second aspect, the node information supplied from the navigation device has at least road kind information and road width information on the road made up of nodes and intersection information indicating whether an intersection exists at each node position; and the front road attribute calculation/storage means judges whether the road represented by the node is the main road based on the road kind information and the road width information and, if so, judges whether an intersection exists on the main road based on the intersection information, and, when an intersection exists on the main road and road widths at the nodes following the intersection are and continue to be less than a road width of a node immediately preceding the intersection, the front road attribute calculation/storage means sets a road segment following the intersection as an exit road from the main road.
In a curve approach control apparatus of a fifth aspect of the present invention according to the first or second aspect, the node information supplied from the navigation device has at least road kind information and road width information on the road made up of nodes and intersection information indicating whether an intersection exists at each node position; and the front road attribute calculation/storage means judges whether an intersection exists at the node position based on the intersection information and judges whether a road following the node where it is decided that an intersection exists is a main road based on the road kind information and the road width information, and, when the judge finds that the main road exists following the intersection and that node intervals preceding the intersection are and continue to be less than a predetermined multiple of the road widths at nodes following the intersection, the front road attribute calculation/storage means sets the road segment preceding the intersection as an entrance road to the main road.
In a curve approach control apparatus of a sixth aspect of the present invention according to the first or second aspect, the node information supplied from the navigation device has at least road kind information and road width information on the road made up of nodes
Fuji Jukogyo Kabushiki Kaisha
Nguyen Tan
Smith , Gambrell & Russell, LLP
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