Patent Application
20180362001
This international application is based on and claims the benefit of priority from earlier Japanese Patent Application No. 2015-237545 filed Dec. 4, 2015, the description of which is incorporated herein by reference.
The present disclosure relates to a technique of controlling vehicle speed of an own vehicle.
As a technique of controlling traveling of a vehicle, various techniques are known such as a technique of auxiliary supporting a driving force, braking force, a steering angle, or the like, with respect to driving manipulation of a driver, and a technique of automatically performing all traveling control on behalf of a driver.
In the technique disclosed in PTL 1, a curve starting point on a curved road is detected as a deceleration point at which the speed should be reduced to a target speed. Then, in the technique disclosed in PTL 1, the target speed at the curve starting point on the curved road is set using any one of an allowable lateral acceleration and a road surface friction coefficient, set in advance, and a turning radius of an own vehicle in order that the vehicle safely passes through the curved road.
If the own vehicle continues to decelerate when the own vehicle enters the curved road, because a passenger feels both force of inertia and centrifugal force by deceleration, there is a case where the passenger feels discomfort.
In contrast, according to the technique of PTL 1, because the own vehicle enters the curved road after the own vehicle decelerates to the target speed, it is possible to prevent a passenger from feeling the force of inertia due to deceleration when the own vehicle enters the curved road.
However, as a result of detailed study by the inventors, a problem has been found that, if acceleration of a vehicle is started before the vehicle exits a curved road in order that acceleration of the vehicle is immediately completed when the vehicle exits the curved road, because a passenger of the vehicle feels both force of inertia and centrifugal force by the acceleration, there is a case where the passenger feels discomfort.
One aspect of the present disclosure provides a technique of suppressing discomfort which is felt by the passenger of the vehicle when the vehicle enters the curved road and when the vehicle exits the curved road.
A traveling control apparatus according to one aspect of the present disclosure includes a shape acquiring unit and a vehicle speed control unit.
The shape acquiring unit acquires a shape of a road on which the own vehicle is to travel. The vehicle speed control unit sets a deceleration start position at which the own vehicle is caused to start deceleration so that the own vehicle enters a curved road at a constant speed at a time when the own vehicle enters the curved road in the case where the shape of the road acquired by the shape acquiring unit changes from a straight road to the curved road, and sets an acceleration start position at which the own vehicle is caused to start acceleration from a time when the own vehicle exits the curved road in the case where the shape of the road acquired by the shape acquiring unit changes from the curved road to the straight road.
According to this configuration, because the own vehicle enters the curved road at constant speed after the vehicle speed is reduced before the own vehicle enters the curved road, a passenger of the own vehicle does not feel the force of inertia caused by deceleration when the own vehicle enters the curved road.
Further, because the own vehicle accelerates after the own vehicle exits the curved road, the passenger of the own vehicle does not feel the force of inertial due to acceleration when the own vehicle exits the curved road, nor the centrifugal force when the own vehicle exits the curved road and accelerates.
Therefore, in one aspect of the present disclosure, when the own vehicle enters the curved road, and when the own vehicle exits the curved road, it is possible to suppress discomfort which is felt by the passenger of the own vehicle.
Note that reference numerals in parentheses recited in the claims indicate correspondence relationship with specific means described in an embodiment which will be described later as one aspect and do not limit the technical scope of the present disclosure.
An embodiment to which the present disclosure is applied will be described below on the basis of the drawings.
A traveling control system 2 illustrated in
The traveling control apparatus 10 in which a computer including a CPU, a RAM, a ROM, a flash memory, an I/O interface, or the like, is mounted, includes a shape acquiring unit 12, a vehicle speed setting unit 14 and a vehicle speed control unit 16. The traveling control apparatus 10 executes a traveling control function corresponding to a program by executing the program recorded in a non-transitory recording medium such as a ROM or a flash memory.
The shape acquiring unit 12 acquires a shape of a road 200 on which the own vehicle 100 travels from image data ahead of the own vehicle 100 captured by the camera 20, map information of a map DB provided at the navigation apparatus 22, or the like.
The vehicle speed setting unit 14 sets a target speed of the own vehicle 100 on the basis of the shape of a road ahead of the own vehicle 100, acquired by the shape acquiring unit 12. As illustrated in
In the case where the own vehicle 100X) travels on the curved road 204, the vehicle speed setting unit 14, for example, sets an upper limit speed which prevents the own vehicle 100 from skidding off outside the curved road 204 as the target speed.
The vehicle speed control unit 16 controls the powertrain system 30 and the brake system 32 so that the vehicle speed of the own vehicle 100 becomes the target speed set by the vehicle speed setting unit 14. The camera 20, which is attached, for example, near the center of a mirror of a window shield within a vehicle interior of the own vehicle, captures an image ahead of the own vehicle 100 to output image data.
The navigation apparatus 22 guides a driver through a route to a destination on the basis of a current location of the own vehicle 100 and the destination of the own vehicle 100 input from a touch panel, or the like. The navigation apparatus 22 receives a positioning signal from a positioning satellite such as a GPS satellite and maps a location of the own vehicle on the basis of the map information stored in the map DB. In the map information stored in the map DB, a type of the road, a speed limit of the road, a radius of a curvature of the road, a gradient of the road, or the like, are stored.
The navigation apparatus 22 acquires a speed limit of the road 200 on which the own vehicle 100 is traveling and acquires a radius of a curvature if the road is a curve, from the map information of the map DB and the location of the own vehicle detected by the navigation apparatus 22 receiving the positioning signal from the positioning satellite such as a GPS satellite.
The vehicle speed sensor 24 detects the vehicle speed of the own vehicle 100.
The powertrain system 30 controls opening and a fuel injection amount of a throttle apparatus in the case where an internal combustion is mounted as a drive source in accordance with drive output commanded from the vehicle speed control unit 16, and controls power to be supplied to a motor in the case where the motor is mounted as the drive source.
The brake system 32 controls an actuator provided at a hydraulic circuit of a hydraulic brake in accordance with braking force commanded from the vehicle speed control unit 16. In the case where a motor is mounted on the own vehicle 100 as the drive source, the brake system 32 may control power to be supplied to the motor to generate braking force by a regenerative brake in accordance with the braking force commanded from the vehicle speed control unit 16.
Traveling control processing to be executed by the traveling control apparatus 10 will be described below on the basis of the flowchart in
In S400, the shape acquiring unit 12 acquires a shape of the road 200 ahead on which the own vehicle 100 travels on the basis of at least one of the image data ahead of the own vehicle 100 captured by the camera 20 and the map information stored in the map DB provided at the navigation apparatus 22.
For example, as illustrated in
Further, the shape acquiring unit 12 may acquire a shape of the road 200 ahead from the map information stored in the map DB and the location of the own vehicle detected from the positioning signal of the positioning satellite.
In S402, the vehicle speed control unit 16 determines whether the road ahead is a curved road 204 on the basis of the shape of the road 200 ahead acquired by the shape acquiring unit 12.
In the case where the determination in S402 is No. and the road ahead is not a curved road 204 but a straight road 202, the processing shifts to S410.
In the case where the determination in S402 is Yes, and the road 200 ahead is a curved to road 204, in S404, the vehicle speed setting unit 14 calculates an upper limit speed which prevents the own vehicle 100 from skidding off outside the curved road 204 when the own vehicle 100 travels on the curved road 204. To prevent the own vehicle 100 from skidding, it is necessary that the friction force Ft between a tire and the road surface applied to the own vehicle 100 in a direction opposite to centrifugal force Fv is larger than the centrifugal force Fv applied to the own vehicle 100.
Here, when acceleration of gravity is g, mass of the own vehicle 100 is M, the vehicle speed of the own vehicle 100) is v, a radius of a curvature of the curved road 204 is r, and a friction coefficient between the own vehicle 100 and the road surface on which the own vehicle 100 is to travel is p, the centrifugal force Fv can be expressed with the following equation (1), and the friction force Ft can be expressed with the following equation (2). The friction coefficient μ is set, for example, assuming a case where the own vehicle travels on a wet road surface to minimize occurrence of skidding of the own vehicle 100.
Fv=Mv
2
/r (1)
Ft=μMg (2)
Further, from relationship of the following equation (3), in a speed range which satisfies the following equation (4), it is possible to prevent the own vehicle 100 from skidding off toward outside of the curved road 204.
Fv=Mv
2
r<Ft=μMg (3)
v
2
/r<μg (4)
In S404, the vehicle speed setting unit 14 sets an upper limit obtained by subtracting a detection error of a sensor, or the like, and a deceleration amount set appropriately on the basis of a road surface state and the vehicle speed of the own vehicle 100 from the speed v calculated using the equation (4) as an equality, as an upper limit speed of the own vehicle 100 within a range 10o satisfying the equation (4). The vehicle speed setting unit 14 sets the upper limit speed as a target speed when the own vehicle 100 travels on the curved road 204.
In S406, the vehicle speed control unit 16 determines whether the own vehicle 100 is located at a deceleration start position 220 at which the own vehicle 100 starts deceleration so that the own vehicle 100 enters the curved road 204 at constant speed at a time point when the own vehicle 100 enters the curved road 204.
Whether the own vehicle 100 is located at the deceleration start position 220 is determined in accordance with whether a position where the own vehicle 100 is located is a distance of Li [m] or time of ti [sec] illustrated in
In the case where, in a state where there is the curved road 204 ahead of the own vehicle 100, the determination in S406 is No, and a position of the own vehicle 100 is not the deceleration start position 220 which is located Li [m] or ti [sec] on this side of the entry of the curved road 204, it is considered that the own vehicle 100 is traveling on the curved road 204.
In this case, the vehicle speed control unit 16 judges that processing of decelerating the own vehicle 100 from the deceleration start position 220 to the entry of the curved road 204 is finished in processing in S408 which will be described later, and the process shifts to S422.
In the case where, in a state where there is the curved road 204 ahead of the own vehicle 100, the determination in S406 is Yes, and the own vehicle 100 is located at the deceleration start position 220, in S408, as illustrated in
In S410, the vehicle speed control unit 16 determines whether the own vehicle 100 is exiting a curved road 204 in a state where the road 200 ahead of the own vehicle 100 is not a curved road 204, but a straight road 202. In the case where the determination in S410 is No, and the own vehicle 100 is not leaving the curved road 204, it is considered that the own vehicle 100 is traveling at a straight portion of the road 200. In this case, the processing shifts to S420.
In the case where the determination in S410 is Yes, and the own vehicle 100 exits the curved road 204, in S412, the vehicle speed control unit 16 determines whether the own vehicle 100 is located at an acceleration start position 230 at which the own vehicle 100 starts acceleration from a time point when the own vehicle 100 exits the curved road 204. In the case where the determination in S412 is No, the processing shifts to S420.
The vehicle speed control unit 16 may set as the acceleration start position 230 a fixed value which corresponding to an exit of the curved road 204 as illustrated in
In the case where the determination in S412 is Yes, in S414, the vehicle speed setting unit 14 sets a target speed when the own vehicle 100 travels on the straight road 202 after the own vehicle 100 exits the curved road 204 and finishes acceleration. For example, the vehicle speed setting unit 14 sets a speed limit specified on a road sign as the target speed.
In S416, the vehicle speed control unit 16 accelerates the own vehicle 100 until the determination in S418 becomes Yes and the own vehicle 100 reaches an acceleration completion position 232. The vehicle speed control unit 16 issues a control amount of the driving force and the braking force to the powertrain system 30 and the brake system 32 to increase the vehicle speed of the own vehicle 100.
As illustrated in
The vehicle speed control unit 16 may set a fixed value at the acceleration completion position 232 indicated by Lo [m] or to [sec], or may set the acceleration completion position 232 in accordance with the difference between the target speed when the own vehicle 100 travels on the curved road 204 and the target speed when the own vehicle 100 passes through the curved road 204 and travels on the straight road 202.
Further, because acceleration through accelerator operation requires a longer time period than deceleration through brake operation, Lo [m] may be set longer than Li [m], and to [sec] may be set longer than ti [sec].
In S420, the vehicle speed setting unit 14 sets the target speed when the own vehicle 100 travels on the straight road 202. As described above, the vehicle speed setting unit 14 sets, for example, a speed limit specified on a road sign as the target speed.
In S422, the vehicle speed control unit 16 issues a control amount of the driving force and the braking force to the powertrain system 30 and the brake system 32 so that the actual vehicle speed reaches the target speed, on the basis of the difference between the target speed set in S404 or S420 and the actual vehicle speed detected by the vehicle speed sensor 24.
In the above-described embodiment described above, the own vehicle 100 decelerates from the deceleration start position 220 so that the own vehicle 100 enters the curved road 204 at constant speed at a time point when the own vehicle 100 enters the curved road 204. Further, the own vehicle 100 accelerates from the acceleration start position 230 at which the own vehicle 100 starts acceleration to the acceleration completion position 232 from a time point when the own vehicle 100 exits the curved road 204. That is, acceleration and deceleration of the own vehicle 100 are not performed while the own vehicle 100 is traveling on the curved road 204.
By this means, because the passenger does not feel the force of inertia due to acceleration and deceleration while the own vehicle 100 is traveling on the curved road 204, it is possible to suppress discomfort to be felt by the passenger due to both centrifugal force and the force of inertia due to acceleration and deceleration while the own vehicle 100 is traveling on the curved road 204.
(1) The friction coefficient to be used for calculating friction force acting in a direction opposite to the centrifugal force may be set as appropriate in accordance with the road surface state. For example, the friction coefficient may be set on the basis of weather information acquired from outside through communication, or the driver may input the friction coefficient in the traveling control apparatus 10 on the basis of weather. Further, the friction coefficient for the case where the friction force acting in a direction opposite to the centrifugal force is calculated, may be set on the basis of a slip ratio calculated from the vehicle speed and rotation speed of a tire.
(2) In the above-described embodiment, functions to be executed by the traveling control apparatus 10 are implemented with software by a program, recorded in a non-transitory recording medium such as a ROM and a flash memory, being executed. In contrast, part or all of the functions to be executed by the traveling control apparatus 10 may be configured with hardware using one or more ICs, or the like.
In the case where part or all of the functions of the traveling control apparatus 10 is configured with electronic circuits which is hardware, the functions can be provided using a digital circuit including a number of logic circuits or an analog circuit.
(3) It is also possible to distribute functions of one component in the above-described embodiment as a plurality of components or integrate functions of a plurality of components in one component. Further, part of the components of the above-described embodiment may be omitted. Still further, at least part of the components of the above-described embodiment may be added to or replaced with the components of the above-described other embodiments. Note that any aspect included in technical idea specified only by words recited in the claims is an embodiment of the present disclosure.
(4) Other than the above-described traveling control apparatus 10, the present disclosure can be realized in various forms such as a traveling control system 2 including the traveling control apparatus 10 as a component, a traveling control program for causing a computer to function as the traveling control apparatus 10, a recording medium in which the traveling control program is recorded, and a traveling control method.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-237545 | Dec 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/085969 | 12/2/2016 | WO | 00 |
