JP2010089692A - Steering support device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering support device for performing appropriate steering support according to the steering operation of a driver. <P>SOLUTION: This steering support device applies a steering torque on a steering mechanism so that a vehicle travels along a travelling passage based on the photographed image of the travelling passage ahead of the vehicle. It determines whether the operation of a steering wheel 2 by the driver of the vehicle is performed or not, and when it is determined that the operation of the steering wheel 2 is performed, the limit value of the percentage change of the steering torque is set to be smaller than that in a case without the operation of the steering wheel. This restrains the driver from feeling odd by the steering operation, and enable appropriate steering support. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a steering assistance device that provides steering assistance by applying a steering torque to a steering mechanism of a vehicle.

Conventionally, as an apparatus for assisting steering by applying a steering torque to a steering mechanism of a vehicle, as described in Japanese Patent Application Laid-Open No. 2005-343303, the vehicle speed is determined when it is determined that a running vehicle deviates from the lane. It is known to prevent a lane departure by adding a warning torque corresponding to the vehicle to the vehicle.
JP-A-2005-343303

  However, in such a device, the driver of the vehicle may feel uncomfortable. For example, when a warning torque is applied by steering control when the driver of the vehicle tries to guide the vehicle by steering operation in response to lane departure, the steering wheel operation feels heavy or the steering reaction force is lost. You will feel uncomfortable.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a steering assistance device that can perform appropriate steering assistance in accordance with a driver's steering wheel operation.

  That is, a steering assist device according to the present invention is a steering assist device that applies a steering torque to a steering mechanism so that the vehicle travels along a travel path based on an image of a travel path ahead of the vehicle. The steering control means is configured to set the limit value of the rate of change of the steering torque smaller when the driver performs the steering operation than when there is no steering operation and suppress the output of the steering torque. ing.

  According to the present invention, when the steering operation is performed by the driver, the limit value of the change rate of the steering torque of the steering control is set smaller than when the steering operation is not performed, and the output of the steering torque is suppressed. The steering operation can prevent the driver from feeling uncomfortable, and appropriate steering assistance can be performed.

  In the steering assist device according to the present invention, it is preferable that the steering assist device includes a steering operation determination unit that determines whether or not a steering operation has been performed by a driver of the vehicle.

  In the steering assist device according to the present invention, the steering control means may determine that the steering operation of the vehicle has been performed and the steering direction of the steering operation is the same as the steering direction of the steering torque. It is preferable to suppress the output of the steering torque by setting a limit value of the rate of change of the steering torque smaller than that in the case where there is no steering operation.

  According to the present invention, when the steering direction of the steering operation by the driver is the same as the steering direction of the steering torque by the steering control, the limit value of the change rate of the steering torque is made smaller than when the steering operation is not performed. By setting and suppressing the output of the steering torque, it is possible to suppress the driver from feeling uncomfortable by operating the steering wheel, and appropriate steering assistance can be performed.

  ADVANTAGE OF THE INVENTION According to this invention, when there is a driver | operator's steering wheel operation, the output of the steering torque by steering control can be reduced, and it can suppress that a driver | operator feels strange about steering wheel operation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic configuration diagram of a steering assist device according to an embodiment of the present invention.

  As shown in FIG. 1, a steering assist device 1 according to the present embodiment is a device that provides steering torque to a steering force transmission system of a vehicle to assist the driver of the vehicle. Used for lane keeping control that maintains the position of the vehicle at the center position. A vehicle steering force transmission system, that is, a steering mechanism, includes a steering shaft 3, a gear portion 4, and a tie rod 6 as main components. The steering shaft 3 is connected to the handle 2 and transmits the steering force of the handle 2 to the gear portion 4 and the tie rod 6.

  The gear unit 4 converts the steering torque transmitted from the steering shaft 3 into a horizontal force. As the gear part 4, a rack and pinion type, for example, is used. The gear portion 4 receives the assist force of the motor 5 and moves the tie rod 6 to steer the steered wheels 7.

  The gear unit 4 is provided with a torque sensor 8. The torque sensor 8 functions as a steering torque detection means for detecting the steering torque of the handle 2. As this torque sensor 8, for example, a torsion bar (not shown) is arranged between the steering shaft 3 and a pinion shaft (not shown), and the torsion bar is twisted according to the steering torque by two rotation sensors (not shown). What is detected by is used.

  The motor 5 is a motor that assists the steering force of the handle 2 and functions as a steering actuator. The motor 5 gives an assist force according to, for example, a steering torque to the steering force transmission system. In FIG. 1, the motor 5 is of a rack assist type that gives an assist force to the rack, but may be of a column assist type or the like.

  The steering assist device 1 is provided with an ECU (Electronic Control Unit) 20. The ECU 20 performs control processing for the entire apparatus, and includes, for example, a CPU, a ROM, a RAM, an input signal circuit, an output signal circuit, a power supply circuit, and the like. The steering assist device 1 is provided with a camera 11. The camera 11 functions as an imaging unit that images the front of the vehicle. For example, a CCD camera or the like is used. Image information captured by the camera 11 is input to the ECU 20.

  The ECU 20 functions as a vehicle position detection unit that detects the position of the vehicle with respect to the width direction of the travel path based on the image information. For example, the ECU 20 performs image processing on the captured image, recognizes a white line (lane marker) included in the image information, and detects the position of the vehicle with respect to the width direction of the travel path based on the recognized shape and position of the white line. . At that time, the positional deviation of the vehicle from the center position of the lane is referred to as an offset.

  Further, the ECU 20 functions as a handle operation determining means for determining whether or not a handle operation has been performed by the vehicle driver. For example, it is determined whether or not the driver has operated the steering wheel based on the detection signal of the torque sensor 8.

  In addition, the ECU 20 functions as a steering control unit that executes steering control. The basic operation of the steering control will be described later. When the ECU 20 determines that the driver has operated the steering wheel, the ECU 20 sets the limit value of the rate of change of the steering torque in the steering control to be smaller than that in the case where it is determined that there is no steering wheel operation, thereby suppressing the output of the steering torque. For example, when the vehicle deviates from the lane and the driver is trying to return the vehicle to the lane center side by a steering wheel operation, the output value of the steering torque is suppressed by setting the limit value of the change rate of the steering torque to be small, The driver is prevented from feeling uncomfortable with the steering wheel operation.

  The steering assist device 1 is provided with a vehicle speed sensor 12. The vehicle speed sensor 12 functions as a vehicle speed detection unit that detects the traveling speed of the vehicle.

  FIG. 2 is a schematic diagram of a basic control block of the steering assist control in the steering assist device 1 according to the present embodiment.

  As shown in FIG. 2, in the steering assist device 1, image information of the traveling road ahead of the vehicle imaged by the camera 11 is input to the ECU 20, and the curvature (R) of the traveling road, the vehicle position ( D) and the vehicle orientation (θ) relative to the white line are detected. The curvature of the traveling road is calculated based on, for example, the detection state of the white line on the traveling road. The vehicle position is a position with respect to the width direction of the travel path of the vehicle. This vehicle position is calculated based on, for example, a white line detection state. The direction of the vehicle with respect to the white line is calculated based on the detection state of the left and right white lines, for example.

  The curvature of the travel path, the vehicle position, and the vehicle direction are each multiplied by a predetermined gain (G) and then used for calculating the target lateral acceleration. The target lateral acceleration is a lateral acceleration necessary for returning the vehicle to the center of the lane. Then, by multiplying the target lateral acceleration by a predetermined coefficient, a steering torque (assist steering force) necessary for maintaining the lane is calculated. At this time, if the steering torque exceeds a preset change rate limit value, the change rate limit value is calculated as the steering torque value. This steering torque is applied to the steering mechanism.

  On the other hand, an actuator (motor 5) of an electric power steering (EPS) applies an assist force in accordance with the steering force of the driver of the vehicle. A steering wheel steering force and an assisting force are applied to the steering mechanism from the actuator of the electric power steering.

  The steering mechanism is provided with steering force, steering assist force, and assist steering force for maintaining the lane as steering force. In response to the steering force, the traveling direction of the vehicle changes.

  3 and 4 are flowcharts showing a steering direction determination process in the steering assist device 1 according to the present embodiment.

  This steering direction determination process is a process for determining the steering direction by the steering operation of the driver of the vehicle. A series of control processes in FIGS. 3 and 4 are repeatedly executed by the ECU 20 at a predetermined cycle, for example.

  First, as shown in S10 of FIG. 3, it is determined whether or not the previous value of the right steering flag is OFF. The right steering flag is a flag indicating whether or not the driver of the vehicle is steering in the right direction. When the right steering flag is on, the driver is steering in the right direction. When the right steering flag is off, the driver is not steering in the right direction.

  When it is determined in S10 that the previous value of the right steering flag is not OFF, it is determined whether or not the steering input torque is smaller than the set value MT2 (S12). As the steering input torque, for example, a torque value output from a steering torque sensor is used. The set value MT2 is a set value set in advance in the ECU 20, and is set to a positive value. The steering input torque is represented as-for left steering and + for right steering.

  If it is determined in S12 that the steering input torque is not smaller than the set value MT2, the process proceeds to S24. On the other hand, when it is determined in S12 that the steering input torque is smaller than the set value MT2, the right steering flag is set to OFF (S14).

  When it is determined in S10 that the previous value of the right steering flag is OFF, it is determined whether or not the steering input torque is greater than the set value MT1 (S16). The set value MT1 is a set value set in advance in the ECU 20, and is set to a positive value larger than the set value MT2. If it is determined in S16 that the steering input torque is not greater than the set value MT1, the right steering timer is reset (S18). On the other hand, if it is determined in S16 that the steering input torque is greater than the set value MT1, the right steering timer is incremented (S20).

  Then, the process proceeds to S22, where it is determined whether or not the right steering timer has exceeded a predetermined time T3. The time T3 is a set time set in the ECU 20 in advance. If it is determined in S22 that the right steering timer has not exceeded the predetermined time T3, the right steering flag is set to OFF (S14). On the other hand, if it is determined in S22 that the right steering timer has exceeded the predetermined time T3, the right steering flag is set to ON (S24). Then, the process proceeds to S26, where the current value of the right steering flag is set as the previous value of the right steering flag.

  Then, the process proceeds to S28 in FIG. 4, and it is determined whether or not the previous value of the left steering flag is OFF. The left steering flag is a flag indicating whether or not the driver of the vehicle is steering leftward. When the left steering flag is on, the driver is steering leftward, and when the left steering flag is off, it indicates that the driver is not steering leftward.

  When it is determined in S28 that the previous value of the left steering flag is not OFF, it is determined whether or not the steering input torque is larger than the set value −MT2 (S30). If it is determined in S30 that the steering input torque is not greater than the set value −MT2, the process proceeds to S32. On the other hand, if it is determined in S30 that the steering input torque is greater than the set value −MT2, the left steering flag is set to OFF (S32).

  When it is determined in S28 that the previous value of the left steering flag is OFF, it is determined whether or not the steering input torque is smaller than the set value −MT1 (S34). If it is determined in S34 that the steering input torque is not smaller than the set value -MT1, the left steering timer is reset (S36). On the other hand, if it is determined in S34 that the steering input torque is smaller than the set value −MT1, the left steering timer is incremented (S38).

  Then, the process proceeds to S40, where it is determined whether or not the left steering timer has exceeded a predetermined time T3. If it is determined in S40 that the left steering timer has not exceeded the predetermined time T3, the left steering flag is set to OFF (S32). On the other hand, if it is determined in S40 that the left steering timer has exceeded the predetermined time T3, the left steering flag is set to ON (S42). Then, the process proceeds to S44, where the current value of the left steering flag is set as the previous value of the left steering flag. Then, when the process of S44 is completed, a series of the steering direction determination process is ended.

  According to such steering direction determination processing, it is possible to determine the steering direction of the vehicle according to the steering input by the driver's steering operation.

  In the steering assist device according to the present embodiment, the vehicle steering direction may be determined by a process or method other than the steering direction determination process shown in FIGS. 3 and 4 as long as the vehicle steering direction can be determined. .

  FIG. 5 is a flowchart showing a lane departure determination process in the steering assist device 1 according to the present embodiment.

  This lane departure determination process is a process for determining whether or not the vehicle has deviated from the lane. A series of control processes in FIG. 5 are repeatedly executed by the ECU 20 at a predetermined cycle, for example.

  First, as shown in S50 of FIG. 5, it is determined whether or not the previous value of the lane departure determination flag is OFF. The lane departure determination flag is a flag indicating whether or not the vehicle has deviated from the lane. When this lane departure determination flag is off, it is recognized that the vehicle has not deviated from the lane, and when the lane departure determination flag is left, it is recognized that the vehicle has deviated from the lane to the left, and the lane departure determination flag is In the case of the right, it is recognized that the vehicle deviates from the lane to the right.

  If the previous value of the lane departure determination flag is OFF in S50, it is determined whether or not the offset is larger than the set value L1 (S52). The offset is a lane offset value that indicates the amount of deviation of the vehicle from the center position of the lane to the left and right, and is a positive value when the vehicle position is shifted to the left side from the center position of the lane. When it is shifted to the right, it is calculated to be a negative value. The calculation of the offset is performed according to the detection state of the white line based on the captured image of the camera 11. The set value L1 is a threshold value for determining lane departure, and is set in advance in the ECU 20 as a positive value.

  If it is determined in S52 that the offset is larger than the set value L1, the left is set in the lane departure determination flag (S54). On the other hand, when it is determined in S52 that the offset is not larger than the set value L1, it is determined whether or not the offset is smaller than the set value -L1 (S56). If it is determined in S56 that the offset is smaller than the set value -L1, the right is set in the lane departure determination flag (S58). On the other hand, if it is determined in S56 that the offset is not smaller than the set value -L1, the lane departure determination flag is set to OFF (S62).

  Incidentally, if the previous value of the lane departure determination flag is not OFF in S50, it is determined whether or not the absolute value of the offset is smaller than the set value L2 (S60). The set value L2 is a threshold value for determining lane departure, and is set in the ECU 20 in advance as a positive value. The set value L2 is set to a value smaller than the set value L1.

  If it is determined in S60 that the absolute value of the offset is smaller than the set value L2, the lane departure determination flag is set to OFF (S62). On the other hand, if it is determined in S60 that the absolute value of the offset is not smaller than the set value L2, the previous value is set in the lane departure determination flag (S64).

  Then, the process proceeds to S66, where the value of the lane departure determination flag is set as the previous value of the lane departure determination flag. Then, a series of the lane departure determination process is completed.

  According to this lane departure determination process, it can be determined whether or not the vehicle has deviated from the lane according to the offset value of the vehicle. In the steering assist device 1 according to the present embodiment, such lane departure determination processing is an example of a method for determining lane departure, and lane departure determination may be performed using other methods.

  6 and 7 are flowcharts showing a torque change rate limit value setting process in the steering assist device 1 according to the present embodiment.

  This torque change rate limit value setting process is a process of setting a steering torque change rate limit value in the steering control of the steering assist device 1. The rate-of-change limit value is a value that limits a sudden change in the steering torque, and whether or not the steering operation is performed by the driver of the vehicle, and whether or not the steering direction of the steering wheel is the same direction as the steering torque, Set to a different value. When the steering torque change rate limit value is set to a small value, a large change in the steering torque is suppressed. A series of control processes in FIGS. 6 and 7 are repeatedly executed by the ECU 20 at a predetermined cycle, for example.

  First, as shown in S70 of FIG. 6, it is determined whether or not the vehicle has deviated from the lane and the driver has not steered the steering wheel. That is, it is determined whether or not the previous value of the lane departure determination flag is off, the right steering flag is off, and the left steering flag is off.

  If it is determined in S70 that the vehicle has not deviated from the lane and the driver has not steered the steering wheel, the set value k1 is set to the steering torque change rate limit value (S72). The set value k1 is a default value, and is set as a value larger than the set values k2 and k3 set when the steering wheel is operated. By setting the set value k1 as the change rate limit value, it is possible to quickly guide a vehicle that has deviated from the lane to the lane center side in the steering control of the vehicle.

  On the other hand, if it is determined in S70 that the vehicle has deviated from the lane or the driver is steering the steering wheel, the vehicle has not deviated from the lane and the driver has steered the steering wheel. It is determined whether or not there is (S74). For example, it is determined whether the lane departure determination flag is off and whether the right steering flag or the left steering flag is on.

  If it is determined in S74 that the vehicle has not deviated from the lane and the driver is steering the steering wheel, it is determined whether the steering direction and the direction of the steering torque are the same (S76). ). For example, it is determined whether the right steering flag is on and the steering torque for steering control is greater than the previous value, or the left steering flag is on and the steering torque for steering control is smaller than the previous value. In this case, the steering torque is calculated as positive in the case of right steering and negative in the case of left steering.

  When it is determined in S76 that the steering wheel and the steering torque are not in the same direction, the set value k2 is set as the steering torque change rate limit value (S80). On the other hand, if it is determined in S76 that the steering direction and the steering torque direction are the same, the set value k3 is set as the steering torque change rate limit value (S78).

  The set values k2 and k3 are set values set in advance in the ECU 20, and are set as values smaller than the set value k1 set when the steering wheel is not operated. The set value k3 set when the steering wheel steering and the steering torque are the same is set to a value smaller than the setting value k2 set when the steering wheel and the steering torque are not the same.

  By setting these set values k2 and k3 as change rate limit values, in the steering control of the vehicle, when the driver's steering operation is performed, it is suppressed that the steering torque due to the steering control changes greatly. Can be suppressed from feeling uncomfortable with the steering wheel operation. Further, by suppressing a large change in the steering torque when the steering direction of the steering wheel and the direction of the steering torque are the same, it is possible to suppress a sense of discomfort that causes the steering reaction force to be lost. Then, when the processes of S78 and S80 are finished, a series of control processes of the torque change rate limit value setting process is finished.

  By the way, if it is determined in S74 that the vehicle has deviated from the lane or the driver has not steered the steering wheel, the process proceeds to S82 in FIG. It is determined whether or not the operation is left steering. For example, it is determined whether the lane departure determination flag is right and the left steering flag is on.

  If the lane departure direction is the right side and the steering operation is left steering in S82, it is determined that the steering operation is performed to return to the center side of the lane, and the set value k4 is set as the steering torque change rate limit value. Is set (S84). On the other hand, if it is determined in S82 that the lane departure direction is not the right side or the steering operation is not left steering, it is determined whether the lane departure direction is the left side and the steering operation is right steering. (S86). For example, it is determined whether the lane departure determination flag is on the left and the right steering flag is on.

  If the lane departure direction is the left side and the steering operation is right steering in S86, it is determined that the steering operation is performed to return to the lane center side, and the set value k4 is set as the steering torque change rate limit value. Is set (S84). On the other hand, if it is determined in S86 that the lane departure direction is not the left side or the steering operation is not right steering, it is determined that the steering operation for returning to the lane center side is not performed, and the rate of change in the steering torque The set value k5 is set as the limit value (S88).

  The set values k4 and k5 are set values that are set in the ECU 20 in advance. The set value k4 is set to a value smaller than the set value k5. As a result, when the driver is operating the steering wheel to return to the lane center side, the steering torque of the steering control is prevented from changing greatly, and the driver may feel uncomfortable such as steering wheel reaction force loss. It is suppressed.

  The set value k5 is set so that the steering torque functions as a warning torque. That is, when the driver deviates from the lane and does not avoid it, the set value k5 is set so as to experience the lane departure, and the steering torque functions as a warning torque. Then, when the processes of S84 and S88 are finished, a series of control processes of the torque change rate limit value setting process is finished.

  As described above, according to the steering assist device 1 according to the present embodiment, the limit value of the rate of change in the steering torque of the steering control is set smaller when the steering operation is performed by the driver than when the steering operation is not performed. Thus, the output of the steering torque is suppressed. As a result, the driver can be prevented from feeling uncomfortable due to the steering operation, and appropriate steering assistance can be performed.

  Further, in the steering assist device 1 according to the present embodiment, when the steering direction of the driver's steering wheel operation is the same as the steering direction of the steering torque by the steering control, compared to the case where it is determined that there is no steering wheel operation. The limit value of the rate of change in steering torque is set to a small value to suppress the output of steering torque. As a result, the driver can be prevented from feeling uncomfortable due to the steering operation, and appropriate steering assistance can be performed.

  For example, as shown in FIG. 8, when the vehicle M deviates from the lane and the driver does not operate the steering wheel, the steering torque change rate limit value is set to a large value and a warning torque is added to the vehicle. (FIG. 8 (b) solid line). On the other hand, when the driver is operating the steering wheel to return to the center of the lane, the change rate limit value of the steering torque is set to be small and the steering torque is suppressed from increasing (FIG. 8B). Dashed line). This suppresses the driver from feeling uncomfortable due to the steering operation.

  In addition, embodiment mentioned above shows an example of the steering assistance apparatus which concerns on this invention. The steering assist device according to the present invention is not limited to such a configuration. For example, the steering assist device according to the embodiment is modified so as not to change the gist described in the claims, or applied to other devices. It may be what you did.

1 is a schematic configuration diagram of a steering assist device according to an embodiment of the present invention. It is a block schematic diagram of the steering assistance control in the steering assistance apparatus of FIG. It is a flowchart which shows the steering direction determination process in the steering assistance apparatus of FIG. It is a flowchart which shows the steering direction determination process in the steering assistance apparatus of FIG. It is a flowchart which shows the lane departure determination process in the steering assistance apparatus of FIG. It is a flowchart which shows the torque change rate limitation value setting process in the steering assistance apparatus of FIG. It is a flowchart which shows the torque change rate limitation value setting process in the steering assistance apparatus of FIG. It is explanatory drawing of the steering control in the steering assistance apparatus of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering assistance apparatus, 2 ... Handle, 11 ... Camera, 12 ... Vehicle speed sensor, 20 ... ECU.

Claims (3)

In a steering assist device that applies a steering torque to a steering mechanism so that the vehicle travels along a travel path based on an image of a travel path ahead of the vehicle,
Steering control means for setting the limit value of the change rate of the steering torque to be smaller when the steering operation of the vehicle is performed than when the steering operation is not performed, and suppressing the output of the steering torque;
A steering assist device characterized by the above.   The steering assist device according to claim 1, further comprising a handle operation determination unit that determines whether or not a handle operation has been performed by a driver of the vehicle. When the steering operation of the vehicle is performed and the steering direction of the steering operation is the same as the steering direction of the steering torque, the steering control means is compared with the case where the steering operation is not performed. Setting the torque change rate limit value small to suppress the output of the steering torque,
The steering assist device according to claim 1 or 2.

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