Vehicle cruise control system and road condition estimating system

Abstract

An object of the invention is to provide a vehicle automatic running control system, according to which the vehicle automatic control operation is carried out as long as possible, even when the vehicle is running on a punishing road. For that purpose, the system of the invention determines a degree of concavity and convexity of a road surface and prohibits the automatic running control operation when the degree of concavity and convexity of the road surface is larger than a predetermined value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

FIG. 1 is a schematic diagram showing a system structure of a vehicle cruise control system according to a first embodiment of the present invention;

FIG. 2 is a flow chart showing a routine for determining a vehicle automatic running operation;

FIG. 3 is a flow chart showing a routine for the vehicle automatic running operation;

FIGS. 4A to 4C are examples of maps for respectively calculating P gain “Kp”, I gain “Ki”, and D gain “Kd”;

FIG. 5 is a time chart for explaining the vehicle automatic running operation;

FIG. 6 is a schematic diagram showing a system structure of a vehicle cruise control system (a road condition estimating system) according to a second embodiment of the present invention;

FIG. 7 is a flow chart showing a routine for estimating the degree of the concavity and convexity of the road surface;

FIG. 8 is a flowchart showing a routine for renewing a movement model of a vehicle body; and

FIGS. 9A and 9B are time charts for respectively showing an example for a waveform of an input “u” to the movement model of the vehicle body and an example of an output “y” of the movement model of the vehicle body.

Claims

1. A vehicle automatic running control system comprising: a control portion for carrying out an automatic running control, in which a vehicle speed is automatically controlled, when a running mode is set to an automatic running control mode;a determining portion for determining a degree of concavity and convexity of a road surface, on which the vehicle is running; anda prohibiting portion for prohibiting the automatic running control when the degree of concavity and convexity of the road surface is larger than a predetermined value.

2. A vehicle automatic running control system according to claim 1, further comprising: a vehicle speed sensor for detecting a vehicle speed,wherein the prohibiting portion does not prohibit the automatic running control even when the degree of concavity and convexity of the road surface is larger than the predetermined value, if the vehicle speed detected by the vehicle speed sensor is lower than a predetermined value.

3. A vehicle automatic running control system according to claim 1, further comprising: a steering angle sensor for detecting a steering angle,wherein the prohibiting portion does not prohibit the automatic running control even when the degree of concavity and convexity of the road surface is larger than the predetermined value, if the steering angle detected by the steering angle sensor is lower than a predetermined value.

4. A vehicle automatic running control system according to claim 1, further comprising: a control gain varying portion for changing control gains for the automatic running control depending on the degree of the concavity and convexity of the road surface.

5. A vehicle automatic running control system comprising: a control portion for carrying out an automatic running control, in which a vehicle speed is automatically controlled, when a running mode is set to an automatic running control mode;a determining portion for determining a degree of concavity and convexity of a road surface, on which the vehicle is running; anda gain varying portion for changing control gains for the automatic running control depending on the degree of the concavity and convexity of the road surface determined by the determining portion.

6. A vehicle automatic running control system according to claim 1, wherein the determining portion for determining the degree of concavity and convexity of the road surface comprises;a means for detecting a relative displacement between a vehicle wheel and a vehicle body or any other information related to the relative displacement;a means for estimating a vertical movement of the vehicle body by a movement model of the vehicle body, which simulates the vertical movement of the vehicle body depending on a vehicle running condition, and in which information for the vehicle running condition is inputted; anda means for estimating the degree of concavity and convexity of the road surface, based on a detected relative displacement between the vehicle wheel and the vehicle body and an estimated vertical movement of the vehicle body.

7. A vehicle automatic running control system according to claim 5, wherein the determining portion for determining the degree of concavity and convexity of the road surface comprises;a means for detecting a relative displacement between a vehicle wheel and a vehicle body or any other information related to the relative displacement;a means for estimating a vertical movement of the vehicle body by a movement model of the vehicle body, which simulates the vertical movement of the vehicle body depending on a vehicle running condition, and in which information for the vehicle running condition is inputted; anda means for estimating the degree of concavity and convexity of the road surface, based on a detected relative displacement between the vehicle wheel and the vehicle body and an estimated vertical movement of the vehicle body.

8. A road condition estimating system for a vehicle comprising: a means for detecting a relative displacement between a vehicle wheel and a vehicle body or any other information related to the relative displacement;a means for estimating a vertical movement of the vehicle body by a movement model of the vehicle body, which simulates the vertical movement of the vehicle body depending on a vehicle running condition, and in which information for the vehicle running condition is inputted; anda means for estimating a degree of concavity and convexity of a road surface, based on a detected relative displacement between the vehicle wheel and the vehicle body and an estimated vertical movement of the vehicle body.

9. A road condition estimating system according to claim 8, wherein information of engine torque is inputted to the movement model of the vehicle body as one of the information for the vehicle running condition, andthe movement model of the vehicle body outputs an estimated amount of the vertical movement of the vehicle body, which is caused by the vehicle running condition identified by the inputted information.

10. A road condition estimating system according to claim 8, wherein information of a steering angle is inputted to the movement model of the vehicle body as one of the information for the vehicle running condition, andthe movement model of the vehicle body outputs an estimated amount of the vertical movement of the vehicle body, which is caused by the vehicle running condition identified by the inputted information.

11. A road condition estimating system according to claim 9, wherein the degree of concavity and convexity of the road surface is estimated based on a difference between the detected relative displacement between the vehicle wheel and the vehicle body and the estimated amount of the vertical movement of the vehicle body.

12. A road condition estimating system according to claim 8, further comprising: a means for storing data for input and output of the movement model of the vehicle body in a re-writable and non-volatile memory, during a time period in which it is determined from the estimation for the degree of the concavity and convexity of the road surface that the vehicle is running on a flat road, anda means for renewing the parameters for the movement model of the vehicle body based on the stored data.