On-vehicle control device

An on-vehicle control device includes: a control unit that controls an attitude of a vehicle based on a value of a behavior sensor that detects a behavior of the vehicle, and prohibits control based on the behavior sensor when the value of the behavior sensor exceeds a threshold; and a travel environment determination unit that determines a travel environment of the vehicle based on image information captured by a camera, and in which the control unit changes the threshold to a lower value based on the travel environment determined by the travel environment determination unit.

TECHNICAL FIELD

The present invention relates to an on-vehicle control device.

BACKGROUND ART

Behavior sensors such as a yaw rate sensor and an acceleration sensor that detect behaviors of a vehicle are mounted on the vehicle. Further, an attitude of the vehicle is controlled based on values of the behavior sensors, and the behavior sensors are made redundant, for example, duplicated for safety reasons.

For example, PTL 1 discloses a device which includes a magnetic sensor detecting magnetism of a magnetic marker embedded in a road and a camera recognizing a white line are provided and in which both the magnetic sensor and the camera output lateral displacement distances, and the equivalent function is replaced with the camera when the magnetic sensor is determined to be faulty.

The vehicle is under the influence of high temperature and vibration, and there is a case where the behavior sensor mounted on the vehicle inputs an incorrect value for a fixed period due to a temporary fault caused by noise or the like. If control intervention is performed based on this sensor value, there is a risk that control such as unintended brake may be performed. Thus, it is required not to perform the control intervention based on the incorrect value of the behavior sensor.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In the device of PTL 1, it is difficult to suppress the control intervention based on the incorrect value of the behavior sensor.

Solution to Problem

According to one aspect of the present invention, an on-vehicle control device includes: a control unit that controls an attitude of a vehicle based on a value of a behavior sensor that detects a behavior of the vehicle, and prohibits control based on the behavior sensor when the value of the behavior sensor exceeds a threshold; and a travel environment determination unit that determines a travel environment of the vehicle based on image information captured by a camera, in which the control unit changes the threshold to a lower value based on the travel environment by the travel environment determination unit.

Advantageous Effects of Invention

According to the present invention, it is possible to suppress control intervention based on an incorrect value of the behavior sensor.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of an on-vehicle control device according to the present invention will be described with reference to the drawings.

FIG.1is an overall configuration diagram illustrating an on-vehicle control device1and a vehicle30. The on-vehicle control device1includes a travel environment determination unit10and a control unit20. The on-vehicle control device1is mounted on the vehicle30.

The travel environment determination unit10includes a camera11, an image recognition unit12, and a travel environment information creation unit13. The camera11is, for example, a stereo camera that captures a front side of the vehicle30in a traveling direction. Image information captured by the camera11is input to the image recognition unit12. The image recognition unit12recognizes the image information, and recognizes how many meters of a straight road a front road where the vehicle is traveling corresponds to and how many meters ahead there is an obstacle on the front side (a vehicle or the like on the front side). In addition, the image recognition unit12obtains a friction coefficient of a road surface on which the vehicle is traveling based on the image information. The friction coefficient of the road surface is obtained, for example, by providing a deflection filter in the camera11, comparing image information of light passing through the deflection filter with a value, obtained by applying a filter such as Fourier transform on the image information of light not passing through the deflection filter, and referring to a dictionary in which a result of the comparison and a friction coefficient μ of the road surface have been recorded. As a result, it is recognized whether or not the road on which the vehicle is traveling is difficult to slip.

The information indicating the straight road, the information indicating the friction coefficient μ of the road surface, and the like, which have been recognized by the image recognition unit12, are input to the travel environment information creation unit13. Vehicle information such as a steering angle is also input from the vehicle30to the travel environment information creation unit13. The travel environment information creation unit13creates travel environment information, which will be described later, based on the input information. For example, if a straight road of a total length of 100 m has been recognized by the image recognition and the steering angle according to the vehicle information is zero, travel environment information indicating that the road is the straight road of 100 m with high reliability is created. The created travel environment information is input to the control unit20.

The control unit20includes a threshold calculation unit21and a control value calculation unit22. The threshold calculation unit21obtains and outputs a control threshold based on the travel environment information input from travel environment information creation unit13and sensor information input from a behavior sensor32of the vehicle30. The behavior sensor32is a yaw rate or a longitudinal G sensor of the vehicle. In general, the control unit20sets a default threshold to an output value of the behavior sensor32such that control intervention based on the behavior sensor32is not performed when a large sensor value exceeding the default threshold is output due to a fault of the behavior sensor32or the like. The default threshold is a default threshold set in advance. Further, in the present embodiment, for example, when the travel environment is favorable and sensor information of a value, equal to or less than the default threshold but is large, is output from the behavior sensor32, the control unit20regards the sensor information as an incorrect value. The incorrect value of the behavior sensor32is temporarily output due to the influence of high temperature, vibration, noise, or the like. In this case, in the present embodiment, the default threshold is changed to a control threshold having a lower value, and the control intervention by the control unit20is suppressed, thereby suppressing the control intervention based on the incorrect value of the behavior sensor32and promoting functional safety. Here, the control intervention is a concept that also includes execution of various types of control based on the sensor information.

The control threshold from the threshold calculation unit21and the sensor value from the behavior sensor32are input to the control value calculation unit22. When no control threshold is input from the threshold calculation unit21, the control value calculation unit22controls the actuator31of the vehicle30based on the input sensor value if the sensor value input from the behavior sensor32is equal to or less than the default threshold. Incidentally, the actuator31is an actuator used for brake control, engine drive control, and the like. On the other hand, when the control threshold is input from the threshold calculation unit21, the control value calculation unit22changes the default threshold of the sensor to a lower control threshold, and as a result, control intervention due to the temporarily incorrect value of the behavior sensor32is suppressed.

The vehicle30includes the actuator31and the behavior sensor32. Further, the vehicle30includes a control system such as an electronic stability control device (not illustrated) controlled by an actuator31and an anti-block brake system (ABS).

FIG.2is a block diagram of the threshold calculation unit21.

The threshold calculation unit21includes a CAN decoder211, an arithmetic unit212, and a threshold table213. The CAN decoder211decodes travel environment information of a CAN data format, which has been input from the travel environment information creation unit13based on the sensor information input from behavior sensor32, and outputs the travel environment data obtained by decoding to the arithmetic unit212. In addition, the CAN decoder211outputs a sensor identifier to the threshold table213.

The arithmetic unit212converts the travel environment information into a format of a condition parameter including Condition 1 to Condition 3 and outputs the converted information to the threshold table213. The threshold table213is a table storing control thresholds associated with sensor identifiers and condition parameters, respectively, and outputs a control threshold that matches the input sensor identifier and condition parameter. Details of the threshold table213will be described later.

FIG.3is a time chart illustrating an output of a general yaw rate sensor and a default threshold, andFIG.4is a time chart illustrating the output of the yaw rate sensor and a threshold change according to the present embodiment. The horizontal axes inFIGS.3and4represent time, and the vertical axes represent an output value of the yaw rate sensor, andFIGS.3and4illustrate an example in which the vehicle has traveled on a curve until time ta, a straight road between time ta and time tb, and then, a curve.

As illustrated inFIG.3, a yaw rate sensor value along with the traveling of the vehicle30varies with time. In general, a default threshold is provided for the output value of the yaw rate sensor such that the output of the yaw rate sensor is prohibited when a large sensor value exceeding a default threshold s2is output due to a fault or the like of the yaw rate sensor. A threshold s1is the smallest value at which control intervention starts, and the control in accordance with the output value of the yaw rate sensor is performed in a range from the threshold s1to the default threshold s2. The control intervention is prohibited at a value exceeding the default threshold s2, which is handled as an obvious fault of the sensor. In general, when the sensor value is equal to or more than the threshold s1in a range of not exceeding the default threshold s2even in a case where the vehicle30is traveling on a straight road, the control intervention by the control system of the vehicle is performed.

In the present embodiment, the default threshold is changed to the control threshold when the vehicle30is traveling on the straight road as illustrated inFIG.4. That is, the default threshold s2is changed to a threshold s3between time ta and time tb. During this period, the control intervention is performed between the threshold s1and the threshold s3, and the control intervention is not performed when the sensor value exceeds the threshold s3. Incidentally, it is also possible to change the default threshold s2to the threshold s1, and in this case, the control intervention is not performed when the sensor value exceeds the threshold s1. In this manner, when the travel environment is favorable, it is possible to suppress the control intervention based on the incorrect value temporarily output from the behavior sensor32due to the influence of high temperature, vibration, noise, or the like.

FIG.5is a view for describing a fault-tolerant time interval (FTTI).

InFIG.5, the horizontal axis represents a lapse of time. A case where the vehicle30is normally operated and a fault has occurred at time t1is illustrated. After the fault at time t1, an abnormality occurs in the vehicle30at time t2. After diagnosis, a fault is detected at time t3. After fail safe, the state is shifted to a safe state. A time from the occurrence of the fault to transition to the safe state is called the fault-tolerant time interval FTTI. The fault-tolerant time interval FTTI can be expressed as the sum of a fault detection time F1from the diagnosis of the occurrence of the fault to the detection of the fault and a fault reaction time F2from the detection of the fault to the transition to the safe state.

FIG.6is a view illustrating a general travel model of the vehicle30based on the yaw rate sensor, andFIG.7is a view illustrating a travel model of the vehicle30based on the yaw rate sensor according to the present embodiment. InFIGS.6and7, a travel path of the vehicle30is the same, andFIGS.6and7illustrate an example in which the vehicle30has traveled on a straight road until time t4, and then, a curve.

As illustrated inFIG.6, a time between time t1and time t4corresponds to the fault-tolerant time interval FTTI. It is assumed that an incorrect value of the yaw rate sensor is generated counterclockwise in the vehicle30at time t1. The incorrect yaw rate sensor value is transmitted to the control unit. In order to return a position of the vehicle30based on the incorrect value after a certain period of time, the electronic stability control device, which is not originally required, is activated, and the vehicle30is controlled to rotate clockwise. Diagnosis is performed between time t2and time t3, and as a result of the diagnosis, it is detected that the yaw rate sensor is faulty, fail safe is performed between time t3and time t4, and control intervention using the yaw rate sensor is prohibited after time t4.

In the present embodiment, as illustrated inFIG.7, an incorrect value of the yaw rate sensor is generated counterclockwise in the vehicle30at time t1, and the incorrect yaw rate sensor value is transmitted to the control unit. Meanwhile, when determining that the vehicle30is traveling on the straight road, the control unit prohibits the control intervention based on the incorrect yaw rate sensor value at time t2′. Further, diagnosis is performed, and as a result of the diagnosis, it is detected that the yaw rate sensor is faulty, fail safe is performed between time t3and time t4, and control intervention using the yaw rate sensor is prohibited after time t4.

FIG.8is a view illustrating a general travel model of the vehicle30based on a longitudinal G sensor, andFIG.9is a view illustrating a travel model of the vehicle30based on the longitudinal G sensor according to the present embodiment. InFIGS.8and9, a travel path of the vehicle30is the same, there is no obstacle on the travel path, and the friction coefficient μ of the road is set to a friction coefficient that does not hinder travel.

As illustrated inFIG.8, a time between time t1and time t4corresponds to the fault-tolerant time interval FTTI. It is assumed that a driver lightly depresses a foot brake at time t1. At this time, if assuming that an incorrect longitudinal G sensor value has been generated, this value is transmitted to the control unit, for example, it is determined as sudden brake, and the ABS, which is not originally required, is activated so as not to lock tires. Diagnosis is performed between time t2to time t3, and as a result of diagnosis, it is detected that the longitudinal G sensor is faulty, fail safe is performed between time t3and time t4, and control intervention using the longitudinal G sensor is prohibited after time t4.

In the present embodiment, it is assumed that the driver lightly depresses the foot brake at time t1as illustrated inFIG.9. At this time, if assuming that an incorrect longitudinal G sensor value is generated, this value is transmitted to the control unit. Meanwhile, the control unit determines that the vehicle30is traveling on a road having no obstacle and having a friction coefficient that does not hinder travel, and prohibits the control intervention based on the incorrect longitudinal G sensor value at time t2′ Then, diagnosis is performed, and as a result of diagnosis, it is detected that the longitudinal G sensor is faulty, fail safe is performed between time t3and time t4, and control intervention using the longitudinal G sensor is prohibited after time t4.

FIG.10is a view illustrating an example of travel environment information created by the travel environment information creation unit13. The travel environment information creation unit13creates the travel environment information illustrated inFIG.10based on information indicating a straight road and information indicating the friction coefficient μ of a road surface, which have been recognized by the image recognition unit12, and vehicle information such as a steering angle from the vehicle30.

Travel environment information C1on the first row ofFIG.10indicates an example of travel environment data including a CAN ID and Data1to Data3. The travel environment information C1indicates that Data1is a straight road, Data2is 100 m, and Data3is the reliability of 90%. That is, the image recognition unit12recognizes that the front side of the vehicle30is the 100 m straight road, and indicates that the reliability of recognition is 90%. Incidentally, the determination on whether the road is a straight road may also be made additionally considering the steering angle of the vehicle information.

Travel environment information C2indicates that there is an obstacle (such as a preceding vehicle) at a distance of 80 m on the front side, and the reliability is 99%. Travel environment information C3indicates that the friction coefficient μ of the road surface on the front side is 0.60 and the reliability is 70%. Here, the reliability represents the reliability of recognition based on a time when an obstacle and a lane are continuously recognized. For example, there is a higher possibility of noise as the recognition time is shorter, and the reliability is lower. Conversely, the recognition is more stable as the recognition time is longer, and the reliability is higher. In addition, for example, if the 100 m straight road is recognized based on the image and the steering angle according to the vehicle information is zero, the reliability is increased.

FIG.11is a view illustrating an example of the threshold table213of the threshold calculation unit21.

The travel environment information is converted into the format of the condition parameter including Conditions 1 to 3 by the arithmetic unit212, and is input to the threshold table213. In addition, the sensor identifier is input from the CAN decoder211to the threshold table213. The threshold table213stores the control threshold to be output in accordance with the input sensor identifier and condition parameter. When the sensor identifier is the yaw rate sensor and the condition parameter is a straight road of 100 m or longer, information D1in the first row ofFIG.11indicates that the control threshold of the yaw rate sensor is 30%. Incidentally, this case corresponds to the favorable travel environment, and the control threshold may be set to 0% regarding that, even if there is an output of the yaw rate sensor, the output is an incorrect output value.

In information D2to information D3, a linear distance is shorter than 100 m, and the control threshold is increased accordingly. Information D4indicates that the control threshold of the longitudinal G sensor is set to 50% when the sensor identifier is the longitudinal G sensor and there is an obstacle on the front side 30 m or farther ahead. In information D5to information D6, when there is an obstacle on the front side within 30 m, the control threshold is increased in accordance with the friction coefficient of the road surface.

Incidentally, the reliability (Data3) of the travel environment data illustrated inFIG.10is not used in the threshold table213illustrated inFIG.11, but may be used. For example, the control threshold to be output is multiplied by % indicating the reliability, and the resultant is output as the control threshold. Specifically, when the control threshold of the yaw rate sensor is 30% and the reliability is 90%, the control threshold of the yaw rate sensor×30%×90% is output as the control threshold.

FIG.12is a flowchart illustrating processing of the travel environment determination unit10.

In Step S40ofFIG.12, image information captured by the camera11is acquired. In Step S41, the image recognition unit12recognizes the image information, and recognizes how many meters the straight road where the vehicle is traveling and how many meters ahead there is an obstacle on the front side. In addition, a friction coefficient of the road is obtained based on the image information of a road surface.

In Step S42, the travel environment information creation unit13creates the travel environment information described inFIG.10based on the recognized image information and the input vehicle information. Further, the created travel environment information is output to the control unit20in the data format of CAN in Step S43. Thereafter, the processing returns to Step S40to repeat the process. As a result, the recognized straight road, the front obstacle, the friction coefficient of road surface, and the like are quantified as the travel environment information, and are output to the control unit20at a constantly set cycle.

FIG.13is a flowchart illustrating processing of the control unit20.

In Step S50ofFIG.13, the travel environment information input from the travel environment information creation unit13and the sensor information of the behavior sensor32input from the vehicle30are acquired. In Step S51, the threshold table213illustrated inFIG.11is referred to based on the sensor identifier and the condition parameter based on the travel environment information. In Step S52, it is determined whether there is an input of a condition parameter matching the threshold table213, and the processing proceeds to Step S53when there is the input of the matching condition parameter, that is, when the threshold is to be changed. In Step S53, the control threshold with the matching condition parameter and sensor identifier is read from the threshold table213and output. Further, the default threshold of the sensor is changed to the control threshold in Step S54, and the processing proceeds to Step S55. The processing also proceeds to Step S55when there is no input of the condition parameter matching the threshold table213in Step S52. Although the actuator31is controlled based on the sensor value output from the behavior sensor32in Step S55, no control intervention is performed when the sensor value exceeds the control threshold when the default threshold of the sensor has been changed to the control threshold.

For example, when it is output that the control threshold of the yaw rate sensor is set to 30% in the case of the straight road of 100 m or longer according to the information D1of the threshold table213illustrated inFIG.11, the control threshold is changed to a value of 30% of the default threshold in Step S54. Further, the control intervention is not performed when the value of the yaw rate sensor exceeds the control threshold in Step S55. In addition, for example, when it is output that the control threshold of the longitudinal G sensor is set to 50% in a case where there is an obstacle on the front side 30 m or farther ahead according to the information D4of the threshold table213illustrated inFIG.11, the control threshold is changed to a value of 50% of the default threshold in Step S54. Further, the control intervention is not performed when the value of the longitudinal G sensor exceeds the control threshold in Step S55.

FIG.14is a view illustrating an operation sequence of the on-vehicle control device.

The travel environment determination unit10acquires vehicle information such as a steering angle from the vehicle and image information from the camera11. Further, the image information is recognized, and travel environment information of the vehicle30is created with reference to the vehicle information and is output to the threshold calculation unit21. The threshold calculation unit21outputs the control threshold with reference to the threshold table213based on the travel environment information and the sensor information from the vehicle30. When no control threshold is input from the threshold calculation unit21, the control value calculation unit22controls the actuator31of the vehicle30based on the input sensor value. In addition, when the control threshold is input from the threshold calculation unit21, the control value calculation unit22changes the default threshold of the sensor to a lower control threshold, and as a result, control intervention due to the temporarily incorrect value of the behavior sensor32is suppressed.

According to the present embodiment, the image information of the camera typically mounted on the vehicle is recognized to suppress the control intervention when the travel environment of the vehicle is favorable, and thus, it is possible to suppress the control intervention based on the temporarily incorrect value of the sensor without multiplexing sensors to be mounted.

According to the above-described embodiment, the following operational effects are obtained.

(1) The on-vehicle control device1includes: the control unit20that controls an attitude of the vehicle30based on a value of the behavior sensor32that detects a behavior of the vehicle30, and prohibits control based on the behavior sensor32when the value of the behavior sensor32exceeds a threshold; and the travel environment determination unit10that determines a travel environment of the vehicle30based on image information captured by the camera11, and in which the control unit20changes the threshold to a lower value based on the travel environment by the travel environment determination unit10. As a result, the control intervention based on the incorrect value of the behavior sensor32can be suppressed.

(2) The control unit20changes the threshold to a lower value when the travel environment is a predetermined travel environment. As a result, the control intervention based on the incorrect value of behavior sensor32can be suppressed in accordance with the predetermined travel environment.

(3) The behavior sensor32is the yaw rate sensor that detects a yaw rate of the vehicle30, and the control unit20changes the threshold of the yaw rate sensor to a lower value when the travel environment determination unit10determines that the vehicle30is traveling on a straight road. As a result, it is possible to suppress the control intervention based on the incorrect value of the yaw rate sensor while the vehicle30is traveling on the straight road.

(4) The travel environment determination unit10acquires information on a steering angle from the vehicle30in addition to the image information captured by the camera11, and determines that the vehicle30is traveling on a straight road. As a result, it is possible to more reliably determine that the vehicle30is traveling on the straight road.

(5) The behavior sensor32is an acceleration sensor that detects a longitudinal acceleration of the vehicle30, and the control unit20changes the threshold of the acceleration sensor to a lower value when the travel environment determination unit10determines that a distance between the vehicle30and the obstacle ahead is equal to or longer than a predetermined distance. As a result, it is possible to suppress the control intervention based on the incorrect value of the acceleration sensor while the vehicle30is traveling on a road having no obstacle on the front side.

(6) The travel environment determination unit10determines a friction coefficient of a road on which the vehicle30is traveling based on the image information captured by the camera11, and the control unit20changes the threshold of the acceleration sensor to a lower value in accordance with the friction coefficient of the road. As a result, it is possible to suppress the control intervention based on the incorrect value of the acceleration sensor during travel on a road having a high friction coefficient.

(7) The threshold table213is further provided to store the travel environment determined by the travel environment determination unit10in association with the threshold, which needs to be changed to a lower value, of the behavior sensor32, and the control unit20reads the threshold, which needs to be changed to a lower value in accordance with the travel environment, from the threshold table213and changes the threshold. As a result, the threshold can be changed in accordance with the travel environment.

Modified Example

The present invention can be implemented by modifying the above-described embodiment as follows.

(1) The description has been given with the example in which the on-vehicle control device1includes the travel environment determination unit10and the control unit20and performs the processing illustrated in the flowcharts ofFIGS.12and13. However, programs illustrated in these flowcharts may be realized by execution using a computer that includes a CPU, a memory, and the like. Further, these programs may be supplied as various forms of computer-readable computer program products such as a recording medium and a data signal (carrier wave).

(2) The description has been given regarding the configuration in which the travel environment determination unit10includes the camera11, the image recognition unit12, and the travel environment information creation unit13. However, the camera11may be configured as a lens of a camera, and a portion corresponding to the travel environment determination unit10having the functions of the image recognition unit12and the travel environment information creation unit13may be configured as a camera or a stereo camera.

The present invention is not limited to the above-described embodiments, and other modes, which are conceivable inside a scope of a technical idea of the present invention, are also included in a scope of the present invention as long as characteristics of the present invention are not impaired. In addition, the invention may be configured by combining the embodiments and modified examples.

The disclosed content of the following priority application is incorporated herein as the citation.

REFERENCE SIGNS LIST