JP2017100625A - Vehicle steering support apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately support a steering even if a factor other than lateral acceleration is exerted when a vehicle itself travels in a curve section.SOLUTION: A vehicle steering support apparatus 10 includes: a lateral acceleration sensor 38 for obtaining lateral acceleration of a vehicle itself; and an EPS system 16 for controlling so as to increase steering-support torque for reducing steering force of a driver proportionately as lateral acceleration G increases. The support apparatus 10 performs turning-support control for the vehicle itself using a brake system 20. The EPS system 16 changes the steering-support torque on the basis of the turning-support control performed by the brake system 20.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a vehicle steering assist device that assists a driver's steering when the host vehicle travels in a curved section.

  When the host vehicle travels on a curved section of the travel path, lateral acceleration acts in the direction opposite to the turning direction. Therefore, the driver must hold (steer) the steering wheel against the lateral acceleration. If the steering wheel steering is weakened, the steering angle of the steering wheel easily changes. In order to reduce such a driver's steering burden, for example, Patent Literature 1 discloses a steering support control device (vehicle steering support device) that applies a steering control torque (steering support torque) by an actuator in a curved section. ) Is disclosed.

  Further, as a so-called electric power steering system, the vehicle steering assist device further increases the driver's rotational operation force if a larger steering assist torque can be applied when the driver steers the steering wheel in a curved section. Can be reduced. That is, the vehicle steering assist device is desired to further reduce the driver's steering force (rotational operation force or steering force) in the steering assist of the curved section receiving the lateral acceleration.

JP-A-11-147473

  However, when the vehicle travels in a curved section, it receives various factors other than the lateral acceleration. Therefore, applying a large steering assist torque does not match the traveling state of the vehicle, and the driver feels uncomfortable with driving. There is a possibility to remember. Factors other than the lateral acceleration include control of the host vehicle itself, such as distributing braking force to the left and right wheels when the host vehicle is turning. For example, a preceding vehicle or an obstacle exists in front of the host vehicle. In addition, the vehicle is affected by the external environment such as the road surface being in a low friction state.

  The present invention has been made in order to solve the above-described problem. When the host vehicle travels in a curved section, the driver can perform appropriate steering assistance even when receiving a factor other than lateral acceleration. It is an object of the present invention to provide a vehicle steering assist device that can drive even better.

  In order to achieve the above object, the present invention reduces the steering force of the driver as the lateral acceleration acquired by the lateral acceleration acquiring means for acquiring the lateral acceleration of the host vehicle increases. And a second steering support unit that performs turning support of the host vehicle by a control different from the first steering support unit. And environment acquisition means for acquiring environment information of the host vehicle, wherein the first steering support means is the turning support by the second steering support means, or the environment acquisition means The steering assist amount is changed based on environmental information.

  According to the above, the first steering assistance means of the vehicle steering assistance device changes the steering assistance amount based on the turning assistance by the second steering assistance means or the environment information of the environment acquisition means, so that the driver can obtain the lateral acceleration. Even if it receives factors other than the above, it is possible to operate the curve section even better. That is, the first steering support means changes the steering support amount in response to a factor other than the lateral acceleration when performing control to reduce the steering force as the lateral acceleration is larger. The amount of support can be adjusted. Therefore, the vehicle steering assistance device can perform steering assistance commensurate with the traveling state of the host vehicle, and can reduce a sense of discomfort given to the driver and provide a comfortable operational feeling.

  In this case, the vehicle steering assistance device includes a steering angle acquisition unit that acquires the steering angle of the host vehicle, and the second steering assistance unit is based on the steering angle acquired by the steering angle acquisition unit as the turning support. The driving force or braking force of the left and right wheels of the host vehicle is distributed to generate the turning amount of the host vehicle, and the first steering support means acquires the turning amount generated by the second steering support means. It is preferable that the corrected lateral acceleration for reducing the lateral acceleration acquired by the lateral acceleration acquisition means is calculated as the turning amount increases, and the steering assist amount is set based on the corrected lateral acceleration.

  The second steering assistance means can turn the host vehicle with a faster response than the first steering assistance means by allocating the driving force or braking force of the left and right wheels based on the steering angle. Accordingly, since the lateral acceleration rises at the initial stage of entering the curved section, the steering assistance amount of the first steering assistance means becomes large and the steering becomes too light for the driver, but the first steering assistance means The steering assist amount is set based on the corrected lateral acceleration to reduce. Therefore, it is possible to prevent the steering from becoming lighter than necessary due to the steering assistance by the first steering assistance means, and it is possible to achieve both turning support with high responsiveness and appropriate steering assistance.

  In addition to the above configuration, the environment acquisition unit includes an obstacle acquisition unit that acquires an obstacle ahead in the traveling direction of the host vehicle, and a vehicle width direction between the obstacle detected by the obstacle acquisition unit and the host vehicle. An overlap amount acquisition means for acquiring an overlap amount of the first steering assisting means, wherein the first steering assisting means increases the inward amount of the overlap amount of the overlap amount acquisition means toward the inside in the turning direction. The correction amount of the lateral acceleration based on the turning amount of the steering assist means may be reduced.

  While traveling in a curved section, if the obstacle acquisition means detects the presence of an obstacle ahead of the traveling direction of the host vehicle and the host vehicle overlaps inside the turning direction, the host vehicle Inward is easier to avoid obstacles. Therefore, the first steering assistance means can increase the steering assistance amount inward in the turning direction by reducing the correction amount of the lateral acceleration based on the turning amount of the second steering assistance means, and the obstacle avoidance performance Can be improved.

  Further, the environment acquisition means includes road surface inclination acquisition means for acquiring a degree of inclination of the traveling road surface of the host vehicle in the width direction, and the first steering support means is configured to acquire the width of the traveling road surface by the road surface inclination acquisition means. The correction amount of the lateral acceleration based on the turning amount of the second steering support means may be reduced as the degree of inclination that decreases from the inner side to the outer side increases.

  When the traveling road surface becomes lower from the inner side in the width direction toward the outer side, the so-called cant road inclination degree increases, it is preferable to perform the steering assist toward the inner side in the turning direction. Therefore, the first steering assistance means can increase the steering assistance amount inward in the turning direction by reducing the correction amount of the lateral acceleration based on the turning amount of the second steering assistance means. Good steering can be carried out in step (b).

  Furthermore, the environment acquisition means includes lane detection means for detecting a lane of a travel path of the host vehicle, and obstacle acquisition means for acquiring an obstacle ahead of the traveling direction of the host vehicle, and the first steering The assisting means reduces or reduces the steering assist amount when the obstacle enters the traveling path of the host vehicle in front of the host vehicle by the lane detecting unit and the obstacle acquiring unit. Is preferred.

  When the steering assistance based on the lateral acceleration is performed by the first steering assistance, and there is a left-right difference or a feeling of sticking in the steering of the driver's steering wheel, an obstacle such as a preceding vehicle is located in front of the traveling path of the own vehicle. When invading, there is a possibility that the obstacle avoidance operation may be uncomfortable. Therefore, when another vehicle enters the travel path of the host vehicle, the discomfort in the avoidance operation can be reduced by reducing or reducing the steering assist amount to zero.

  Still further, it includes a rudder angle obtaining unit for obtaining a rudder angle of the host vehicle, and the environment obtaining unit obtains a normative yaw rate based on at least the rudder angle obtained by the rudder angle obtaining unit; Actual yaw rate acquisition means for acquiring an actual yaw rate actually generated in the host vehicle, and the first steering assist means, when the difference between the reference yaw rate and the actual yaw rate is equal to or greater than a predetermined value, It is preferable to reduce or reduce the steering assist amount.

  In this way, when the difference between the standard yaw rate and the actual yaw rate is greater than or equal to a predetermined value, the first steering assist means performs steering to increase the running stability by the driver by reducing or reducing the steering assist amount. Can be made easier. For example, when the vehicle is oversteering or understeering on a low μ road surface such as a snowy road or freezing, it is possible to prevent steering assistance from being performed to the incision side, and to improve the running stability of the vehicle. Can do.

  According to the present invention, the vehicle steering assistance device allows the driver to drive more satisfactorily by performing appropriate steering assistance even when receiving a factor other than lateral acceleration when the host vehicle travels in a curved section. Can do.

1 is a block diagram illustrating an overall configuration of a vehicle steering assist device according to an embodiment of the present invention. FIG. 2A is a plan view schematically showing a state in which the host vehicle travels a curve, FIG. 2B is a graph showing the relationship between the steering angle and the steering force of the driver in the steering assist control, and FIG. It is a graph which shows the relationship between the lateral acceleration and steering assistance amount in steering assistance control. It is a block diagram which shows the structure of the vehicle steering assistance apparatus which concerns on 1st Embodiment. It is a top view explaining the turning assistance control in the vehicle steering assistance device of FIG. It is explanatory drawing explaining the flow at the time of implementing turning assistance control and steering assistance control in the vehicle steering assistance device of FIG. It is a flowchart which shows the processing flow of EPS_ECU in steering assistance control. FIG. 7A is a plan view illustrating an avoidance operation of a preceding other vehicle by the vehicle steering assist device according to the first application example, and FIG. 7B is an explanatory diagram illustrating an overlap amount between the host vehicle and the other vehicle. It is a block diagram which shows the structure of the vehicle steering assistance apparatus which concerns on a 1st application example. FIG. 9A is an explanatory diagram illustrating a traveling state of a cant road by the vehicle steering assist device according to the second application example, and FIG. 9B is a plan view illustrating an operation of the host vehicle when traveling on the cant road. It is a block diagram which shows the structure of the vehicle steering assistance apparatus which concerns on a 2nd application example. FIG. 11A is a plan view illustrating a state in which another vehicle interrupts during CC control by the vehicle steering assist device according to the second embodiment, and FIG. 11B illustrates an avoidance operation of the host vehicle when interrupting another vehicle is determined. It is a top view. It is a block diagram which shows the structure of the vehicle steering assistance apparatus which concerns on 2nd Embodiment. FIG. 13A is an explanatory diagram showing a state where the host vehicle equipped with the vehicle steering assist device according to the third embodiment is oversteered and the correspondence thereof, and FIG. 13B is an explanation showing a state where the host vehicle is understeered and the correspondence thereof. FIG. It is a block diagram which shows the structure of the vehicle steering assistance apparatus which concerns on 3rd Embodiment.

  Hereinafter, preferred embodiments (first to third embodiments) of a vehicle steering assistance device according to the present invention will be described in detail with reference to the accompanying drawings.

  A vehicle steering assist device 10 according to an embodiment of the present invention is mounted on a host vehicle 12 as shown in FIG. 1, and the host vehicle 12 has an inside of the host vehicle 12 when traveling on a curve (curved section) of a travel path. This is a device that assists the driving of the driver by performing various control processes. The vehicle steering assist device 10 is not limited to the application to the four-wheeled vehicle shown in FIG. 1, and can be applied to various vehicles by making appropriate modifications.

  In particular, the vehicle steering assist device 10 performs steering assist control that sufficiently reduces the steering of the driver's steering wheel 14 (hereinafter referred to as the steering wheel 14) when the host vehicle 12 travels along a curve of the travel path. Here, the term “steering” is used in the present specification to include steering in which the driver rotates the steering wheel 14 and steering in which the driver holds the steering wheel 14 and maintains the steering angle θ. The “steering support control” refers to control in which the vehicle 12 side provides mechanical and electrical support when the driver steers the steering wheel 14.

[Behavior of the vehicle 12 when driving on a curve]
As shown in FIG. 2A, when the host vehicle 12 travels on a curve, the host vehicle 12 centrifuges in the direction opposite to the direction in which the host vehicle 12 bends (inward in the turning direction) (specifically, the normal direction of the curve in the turning direction). Force, that is, lateral acceleration G is received. The lateral acceleration G changes depending on the vehicle speed V of the own vehicle amount 2, the radius of curvature of the curve, etc., and the greater the lateral acceleration G, the stronger the driving force required from the driver. Further, since the lateral acceleration G applies self-aligning torque to the host vehicle 12, when the driver weakens the steering of the handle 14, the steering angle θ of the host vehicle 12 is returned (guided to the outside in the turning direction).

  Then, as shown in FIG. 2B, the conventional general electric power steering system (hereinafter referred to as a conventional device) passively applies driving force according to the steering of the driver's handle 14 as steering assist control. By doing so, the burden on steering is moderately reduced. Therefore, although the driver is supported for turning by the conventional device on the curve, the driver needs a stronger steering force (steering force) as the steering angle θ of the handle 14 becomes larger (one-point difference line in FIG. 2B). See the ascending part). Further, when the steering of the handle 14 is stopped at an arbitrary steering angle θ (see the steering angle stop point St of the one-point difference line in FIG. 2B), the steering support from the conventional device is hardly supported. Therefore, the driver is required to have a steering force, and when the steering force is weakened, the steering angle θ easily returns.

[Outline of Steering Support Control According to the Present Invention]
The vehicle steering assistance device 10 according to the present invention actively performs steering assistance control (lateral acceleration assistance control: refer to the solid line in FIG. 2B) according to the lateral acceleration G received when the vehicle travels while following the steering assistance control of the conventional device. Do it. Therefore, in the steering assist control of the vehicle steering assist device 10, it is possible to apply a larger steering assist torque than that of the conventional device (to give a steering assist amount), and the driver steers the handle 14 with a weak steering force. (See the rising portion of the solid line in FIG. 2B). In addition, even when the steering of the handle 14 is stopped at an arbitrary steering angle θ (see the steering angle stop point St indicated by the solid line in FIG. 2B), the lateral acceleration G with respect to the host vehicle 12 is continued. Assistance is provided, and the steering angle θ is maintained to some extent even when the driver weakens the steering force.

  Further, as described above, as the lateral acceleration G increases, the driver is required to have a steering force. Therefore, the vehicle steering assist device 10 increases the steering assist amount as the lateral acceleration G increases as shown in FIG. 2C. (Steering assist torque) is increased, that is, the steering assist control is increased. Therefore, the driver can lightly steer the steering wheel 14 even when traveling on a sharp curve. Hereinafter, the vehicle steering assist device 10 will be specifically described.

[Overall Configuration of Vehicle Steering Support Device 10]
As shown in FIG. 1, the vehicle steering assist device 10 includes an electric power steering system 16 (first steering assist means: hereinafter referred to as an EPS system 16) and a sensor group that acquires various types of information for traveling of the host vehicle 12. 18. The vehicle steering assist device 10 includes a brake system 20 and a cruise control system 22 (hereinafter referred to as a CC system 22) that perform control using information from the sensor group 18, and cooperates with each other when steering assist control is performed. Thus, the entire traveling of the host vehicle 12 is controlled. Each configuration is connected to a communication line of an in-vehicle network 24 such as CAN or LIN provided in the host vehicle 12 and can communicate information with each other.

  The EPS system 16 performs steering assist control indicated by a solid line in FIG. 2B when the driver steers. As shown in FIG. 1, the EPS system 16 connects the steering wheel 14, the steering wheel 14 and the wheel 26 (front wheel), and transmits the steering force of the driver's steering wheel 14 to the wheel 26. With. The EPS system 16 includes a steering angle sensor 30 and a torque sensor 32, and further includes an EPS electronic control device 34 (hereinafter referred to as EPS_ECU 34) that performs steering assist control processing based on signals from these sensors. The EPS system 16 may be configured to assist the steering of the rear wheels.

  The steering mechanism 28 includes an EPS motor 36 that tilts the drive shaft 28b by applying a driving force or a reaction force (steering assist torque) to a gear mechanism 28c that connects the steering shaft 28a and the drive shaft 28b. The EPS motor 36 generates an appropriate rotational torque (steering assist torque) based on the supply current control by the EPS_ECU 34.

  The steering angle sensor 30 is a steering angle acquisition means for detecting the steering angle θ of the steering mechanism 28, and outputs a detection signal to the EPS_ECU 34. The torque sensor 32 detects the torque Tr applied to the steering mechanism 28 and outputs a detection signal to the EPS_ECU 34. Since the steering angle sensor 30 and the torque sensor 32 acquire and provide information for the EPS system 16 to perform steering support, the steering angle sensor 30 and the torque sensor 32 can also be referred to as the sensor group 18 of the vehicle steering support device 10.

  The EPS_ECU 34 is configured as a computer (including a microcontroller) having an input / output unit, an arithmetic processing unit, and a storage unit (both not shown) as hardware. The EPS_ECU 34 performs steering assist control by causing the arithmetic processing unit to read out and execute a program (not shown) stored in the storage unit. Specific functional units of the EPS_ECU 34 that performs the steering assist control will be described in detail later for each embodiment.

  The sensor group 18 detects the state of the host vehicle 12 and outputs a detection signal to the in-vehicle network 24. Specifically, the sensor group 18 includes a lateral acceleration sensor 38, a vehicle speed sensor 40, a yaw rate sensor 42, a camera 44, and a radar 46. The vehicle steering assist device 10 includes an image processing ECU 48 that processes image information detected by the camera 44 and the radar 46, and outputs information processed by the image processing ECU 48 to the in-vehicle network 24. In other words, the camera 44, the radar 46, and the image processing ECU 48 constitute an imaging processing system 50 (environment acquisition unit) that acquires and processes environment information outside the vehicle. The environment acquisition means may include a navigation device 52 that can detect and provide the position of the host vehicle 12 together with the map information.

  The lateral acceleration sensor 38 is a lateral acceleration acquisition unit that detects a lateral acceleration G that is an acceleration generated in the vehicle width direction of the host vehicle 12, and outputs the detection signal to the in-vehicle network 24. The lateral acceleration sensor 38 is fixed to a predetermined position on the lower side of the host vehicle 12 (for example, the lower side of the seat, the center of the vehicle body, or the like). The lateral acceleration sensor 38 may be a triaxial acceleration sensor that detects not only the lateral acceleration G but also the longitudinal and vertical accelerations of the vehicle.

  The vehicle speed sensor 40 detects the vehicle speed V, which is the speed when the host vehicle 12 is traveling, and outputs it to the in-vehicle network 24. The vehicle speed sensor 40 is provided, for example, near the counter shaft of the wheel 26 or the transmission.

  The yaw rate sensor 42 detects a yaw rate (actual yaw rate Yr) that is a rotational angular velocity around the vertical axis of the host vehicle 12. That is, the yaw rate sensor 42 can be said to be a yaw rate acquisition unit (environment acquisition unit) that acquires environmental information that is the state of the host vehicle 12 during traveling. The yaw rate sensor 42 is provided near the center of gravity of the host vehicle 12, for example.

  As the camera 44, a CCD camera, a C-MOS camera, or the like that mainly captures visible light or infrared light is used. The radar 46 detects an object by transmitting an electromagnetic wave such as a laser beam or a millimeter wave, and receiving and processing a reflected wave from the object. For example, the camera 44 and the radar 46 are attached to the front nose of the host vehicle 12 in order to detect a situation in front of the host vehicle 12. Note that the imaging processing system 50 may be provided with only one of the camera 44 and the radar 46, or may be provided with a plurality of the same type as in a stereo type.

  The image processing ECU 48 performs image processing such as filtering and binarization on the image information acquired by the camera 44, and detects a travel path on which the host vehicle 12 travels, its lane, and a reflected object. Further, the image processing ECU 48 obtains the distance to the object and the two-dimensional information of the object using the phase difference of the image information (reflected wave) acquired by the radar 46. Then, the image processing ECU 48 integrates and processes the information of the camera 44 and the radar 46 so that the state of the road (lane position, etc.), the state of the object on the road (other vehicles, other obstacles) (Distance, motion, etc.) are output as environmental information.

  The navigation device 52 detects the current position of the host vehicle 12 by GPS (Global Positioning System), superimposes the current position on the map information held, and guides the route to the destination of the host vehicle 12. Then, the navigation device 52 outputs to the in-vehicle network 24 the current position of the host vehicle 12 and information on the travel path (curve position, etc.) according to the current position.

  The brake system 20 of the vehicle steering assist device 10 applies braking force to the four wheels 26 of the host vehicle 12 to decelerate or stop the host vehicle 12 when the vehicle is traveling. The brake system 20 controls a braking force of the brake mechanism 56 based on an operation signal (master pressure Mp) of the foot brake 54, which is an operation mechanism, a brake mechanism 56 that actually applies a braking force to the wheels 26, and an operation signal (master pressure Mp) of the foot brake 54. And a brake control ECU 58. The brake system 20 includes an ESC device 60 that performs the vehicle behavior stabilization control (ESC) by appropriately operating the brake mechanism 56.

  The brake mechanism 56 includes a motor cylinder device 58a (see FIG. 3) that supplies or discharges brake fluid under the control of the brake control ECU 58, and a wheel cylinder 58b that is provided on the wheel 26 and applies a braking force by supplying brake fluid. Including. The ESC device 60 is provided between the motor cylinder device 58a and the wheel cylinder 58b.

  The ESC device 60 includes a brake actuator 60a (see FIG. 3) that controls the flow of brake fluid between the motor cylinder device 58a and the wheel cylinder 58b, and an ESC_ECU 62 that is an electronic control device that controls the operation of the ESC device 60. Prepare.

  The ESC_ECU 62 appropriately includes an ABS (Antilock Braking System) function for preventing the wheel 26 from being locked during braking, a TCS (Traction Control System) function for preventing the wheel 26 from idling during acceleration, and a function for suppressing side slip during turning. To control. The brake actuator 60a distributes the braking force under the control of the ESC_ECU 62 during vehicle behavior stabilization control. Since this vehicle behavior stabilization control is known, a detailed description thereof will be omitted.

  Note that the ESC_ECU 62 includes a yaw rate calculation unit (not shown) that calculates a reference yaw rate Yc (see FIG. 14), which is a posture that the host vehicle 12 should face on a curve, for vehicle behavior stabilization control. The calculation method of the reference yaw rate Yc is not particularly limited, but may be set based on the steering angle θ of the steering angle sensor 30. For example, the ESC_ECU 62 can calculate the reference yaw rate Yc based on the steering angle θ and the vehicle speed V of the vehicle speed sensor 40. Then, the ESC_ECU 62 outputs the calculated standard yaw rate Yc to the in-vehicle network 24 in response to a request from another ECU. In that sense, the ESC_ECU 62 is also included in the environment acquisition unit.

  Like the other ECUs, the brake control ECU 58 is configured as an electronic control device and controls the entire brake system 20. The brake control ECU 58 receives signals from the sensor group 18 (lateral acceleration sensor 38, rudder angle sensor 30, vehicle speed sensor 40) in addition to the master pressure Mp which is an operation signal of the foot brake 54, and the brake mechanism 56 together with the ESC_ECU 62. To work properly.

  On the other hand, the CC system 22 of the vehicle steering assist device 10 maintains the speed of the host vehicle 12 at a constant level or maintains the inter-vehicle distance with the preceding other vehicle in order to reduce the driver's fatigue during driving. Control (hereinafter referred to as CC control) is performed. Since the configuration of the CC system 22 is known, a detailed description thereof will be omitted.

  When the host vehicle 12 travels a curve, the vehicle steering assist device 10 performs appropriate steering assist control based on the above configuration to further improve the driver's steering comfort. Hereinafter, some examples of the control when the host vehicle 12 travels along a curve, the situation at the time of traveling, the environment of the curve, and the like will be described, and the configuration and operation contents related to the control will be described.

[Configuration of Vehicle Steering Assist Device 10 according to First Embodiment]
The vehicle steering assist device 10 according to the first embodiment is configured to improve the turning performance of the host vehicle 12 by the brake system 20 when traveling on a curve. That is, the brake system 20 increases the turning performance of the host vehicle 12 on the curve by allocating appropriate braking force to the four wheels 26 of the host vehicle 12 when the host vehicle 12 travels on the curve of the travel path. It is comprised as a 2nd steering assistance means which implements turning assistance control.

  Specifically, the brake control ECU 58 executes a turning support program (not shown) to construct a turning braking control unit 64 and an operation switching unit 66 as functional units as shown in FIG.

  The turning braking control unit 64 operates the brake mechanism 56 when the host vehicle 12 enters the curve, and the braking force is applied to the wheels 26 (one or both of the front wheels and the rear wheels) on the inner side in the turning direction as shown in FIG. Apply loosely. As a result, the host vehicle 12 is easily turned in the turning direction of the curve due to the yaw moment, and can travel while drawing a smooth curve as shown by the solid line in FIG. At the initial stage of the curve, the turning braking control unit 64 receives the master pressure Mp of the foot brake 54, the steering angle θ of the steering angle sensor 30, and the lateral acceleration G of the lateral acceleration sensor 38 (see also FIG. 3). The braking force applied to the wheel 26 on the inner side in the turning direction is calculated by the FF control. The braking force to be calculated may be different between the front and rear wheels 26 or the same.

  Further, the turning braking control unit 64 receives the actual yaw rate Yr from the yaw rate sensor 42 while the vehicle 12 is traveling on the curve, and further, the bending state of the vehicle 12 based on the master pressure Mp, the steering angle θ, and the lateral acceleration G. Is fed back and the braking force is readjusted by FB control. Thereby, the own vehicle 12 turns the curve more stably.

  The operation switching unit 66 of the brake control ECU 58 has a function of switching between the turning support control of the turning braking control unit 64 and the vehicle behavior stabilization control of the ESC_ECU 62. In other words, the turning support control increases the turning performance by applying a weak braking force. When the behavior of the host vehicle 12 is shaken during turning, the vehicle behavior stabilization control is performed to stabilize the running. Can be planned. When the behavior switching unit 66 monitors the behavior of the host vehicle 12 during turning support control and determines that the turning support control has exceeded the limit, the behavior switching unit 66 performs vehicle behavior stabilization control.

  On the other hand, the EPS system 16 includes a basic support unit 70, a lateral acceleration support unit 72, and an addition unit as functional units that perform steering support control when the host vehicle 12 travels a curve due to the execution of the program and the internal circuit structure. Build 74.

  The basic support unit 70 is a control unit that performs basic functions as the EPS system 16, and provides steering support (basic steering support) of a conventional apparatus that applies driving force to the steering mechanism 28 based on the operation of the driver's handle 14. Do. Specifically, the torque Tr detected by the torque sensor 32, the vehicle speed V detected by the vehicle speed sensor 40, and the steering angle θ detected by the steering angle sensor 30 are input to the basic support unit 70. The basic support unit 70 calculates the rotational torque (steering support torque) of the EPS motor 36 based on the torque Tr, the vehicle speed V, and the steering angle θ, sets a supply current amount corresponding to the rotational torque, and supplies the addition unit 74 with the supplied current amount. Output.

  On the other hand, the lateral acceleration support unit 72 performs lateral acceleration steering support that applies a driving force to the steering mechanism 28 based on the lateral acceleration G of the lateral acceleration sensor 38. Specifically, the lateral acceleration support unit 72 calculates a rotation torque (steering support torque) according to the magnitude of the lateral acceleration G, and outputs a supply current amount corresponding to the rotation torque to the addition unit 74. For example, as shown in FIG. 2C, the steering assist torque is set to increase linearly or substantially linearly as the lateral acceleration G increases. The lateral acceleration support unit 72 prepares a map that associates the lateral acceleration G with the steering support torque in advance and refers to the map when acquiring the lateral acceleration G, or applies a correlation function between the lateral acceleration G and the steering support torque. Steering assist torque may be set.

  The adding unit 74 of the EPS_ECU 34 adds the supply current amounts output from the basic support unit 70 and the lateral acceleration support unit 72. The EPS system 16 instructs a power adjustment unit that adjusts the power of the battery (not shown) to supply the amount of current supplied from the addition unit 74, and causes the EPS motor 36 to supply power corresponding to the supply current amount from the power adjustment unit. As a result, the EPS motor 36 operates with an appropriate rotational torque and applies a driving force to the steering mechanism 28.

  And the lateral acceleration assistance part 72 which concerns on 1st Embodiment performs the steering assistance which considered this turning assistance control with implementation of turning assistance control by the brake system 20 mentioned above. Therefore, as shown in FIG. 3, the lateral acceleration support unit 72 constructs a generated yaw moment estimation unit 76, a calculation unit 78, and a lateral acceleration support calculation unit 80 inside. Further, the lateral acceleration support unit 72 receives the signal of the brake system 20 and the vehicle speed V of the vehicle speed sensor 40 via the in-vehicle network 24.

  The generated yaw moment estimating unit 76 receives the braking force (the turning amount of the turning support control) from the turning braking control unit 64 and the vehicle speed V from the vehicle speed sensor 40 during the turning support control. The braking force output from the turning braking control unit 64 may be a physical quantity (a turning amount) such as an estimated lateral acceleration, an estimated yaw rate, or a hydraulic pressure of the brake fluid, and is necessary for calculation by the generated yaw moment estimating unit 76. It is good to convert it appropriately to any dimension.

  The generated yaw moment estimation unit 76 estimates the yaw moment required for turning in the turning support control. The yaw moment applied to the host vehicle 12 in the turning support control can be estimated based on the braking force applied to the wheels 26 on the inner side in the turning direction and the speed of the host vehicle 12. From this estimated yaw moment, the component applied to the lateral acceleration G is extracted and output to the calculation unit 78. The generated yaw moment estimation unit 76 may add various elements (for example, the weight of the host vehicle 12) in addition to the braking force (turning amount) and the vehicle speed V as parameters for estimating the yaw moment. Thereby, the yaw moment can be estimated with higher accuracy.

  The calculation unit 78 calculates the corrected lateral acceleration Cg by inputting the lateral acceleration G of the lateral acceleration sensor 38 and the yaw moment of the generated yaw moment estimation unit 76. Specifically, the lateral acceleration G is corrected to be reduced by subtracting the estimated yaw moment that is the correction amount from the lateral acceleration G acquired by the lateral acceleration sensor 38. The computing unit 78 outputs the calculated corrected lateral acceleration Cg to the lateral acceleration support calculating unit 80.

  The lateral acceleration support calculation unit 80 basically has a function of calculating a steering support torque (amount of supplied current) according to the lateral acceleration G described above. In the first embodiment, the steering assist torque is calculated based on the corrected lateral acceleration Cg acquired from the calculation unit 78. Since the corrected lateral acceleration Cg is a value obtained by correcting the lateral acceleration G to be small, the lateral acceleration support calculating unit 80 calculates the supply current amount corrected to be small. Then, the lateral acceleration support calculation unit 80 outputs the calculated supply current amount to the addition unit 74.

  As a result, the EPS system 16 instructs the supply current amount according to the turning support control of the brake system 20, and gives the rotational torque by the EPS motor 36. Therefore, the host vehicle 12 can effectively receive steering assistance (basic steering assistance, lateral acceleration steering assistance) by the EPS system 16 while receiving turning assistance by the brake system 20 in a curve. The vehicle steering assist device 10 according to the present embodiment is basically configured as described above, and the operation and effect thereof will be described below.

[Operation and Effect of Vehicle Steering Assist Device 10 according to First Embodiment]
The vehicle steering assist device 10 is in a standby state in which the EPS system 16 and the brake system 20 are operated when the host vehicle 12 is traveling, and the curve traveling of the host vehicle 12 can be supported. In addition, the torque sensor 32, the vehicle speed sensor 40, the steering angle sensor 30, the lateral acceleration sensor 38, the foot brake 54, and the yaw rate sensor 42 are provided with a torque Tr, a vehicle speed V, a steering angle at regular intervals (or according to an instruction from the ECU). θ, lateral acceleration G, master pressure Mp, and actual yaw rate Yr are detected.

  And the vehicle steering assistance device 10 implements steering assistance control and turning assistance control when the own vehicle 12 enters the curve. In the turning support control, the turning braking control unit 64 of the brake control ECU 58 automatically applies the wheel 26 on the inner side in the turning direction based on the steering angle θ, the lateral acceleration G, and the master pressure Mp as shown in FIG. Apply braking force. Then, the host vehicle 12 positively leans inward in the turning direction and detects the lateral acceleration G as shown in FIG. 5B with the start (fast response) of the turning support control of the brake system 20. .

  Here, if the vehicle steering assist device 10 performs the steering assist control as shown by the solid line in FIG. 2B on the basis of the lateral acceleration G of the turning assist control described above, the steering of the driver's handle 14 is greatly increased. It will be lighter. In this case, as shown in FIG. 5 (C ′), the driver feels a large hesitation in the curve degree of the currently viewed curve and the steering of the handle 14 when entering the curve (in other words, the host vehicle 12 Is likely to be bent too much inward in the turning direction). That is, a comfortable operational feeling cannot be obtained for turning the handle 14.

  On the other hand, the EPS_ECU 34 according to the present embodiment controls the steering wheel 14 so as not to be turned too lightly when the turning support control is performed. Specifically, as shown in FIG. 6, the lateral acceleration support unit 72 acquires the lateral acceleration G from the lateral acceleration sensor 38, and acquires the vehicle speed V from the vehicle speed sensor 40 (step S1). When the host vehicle 12 enters the curve, the braking force applied to the wheel 26 on the inner side in the turning direction is acquired from the turning braking control unit 64 of the brake system 20 (step S2).

  The generated yaw moment estimation unit 76 of the lateral acceleration support unit 72 calculates the estimated yaw moment of the host vehicle 12 applied when entering the curve based on the acquired braking force and the vehicle speed V, and outputs the calculated estimated yaw moment to the calculation unit 78. (Step S3). The computing unit 78 subtracts the estimated yaw moment from the lateral acceleration G of the lateral acceleration sensor 38 to calculate a corrected lateral acceleration Cg, and outputs the corrected lateral acceleration Cg to the lateral acceleration support calculating unit 80 (step S40). S4). That is, the lateral acceleration G of the lateral acceleration sensor 38 is reduced and input to the lateral acceleration support calculation unit 80 than when the EPS_ECU 34 receives the lateral acceleration G.

  The lateral acceleration support calculation unit 80 calculates the steering support torque (the amount of current supplied to the EPS motor 36) based on the input corrected lateral acceleration Cg, and outputs it to the addition unit 74 (step S5). Then, the EPS_ECU 34 outputs the amount of current supplied from the adding unit 74 to the EPS motor 36, rotates the EPS motor 36, and applies driving force to the steering mechanism 28 (step S6). Assist the rudder.

  By repeating the above steps, the EPS_ECU 34 can appropriately perform the driver's steering assistance when the vehicle 12 enters the curve. That is, when turning support is provided by the brake system 20, as shown in FIG. 5C, the corrected lateral acceleration Cg obtained by reducing the normal lateral acceleration G is used as the steering mechanism in the steering support control. 28 driving force can be suppressed. As a result, the steering of the steering wheel 14 does not become too light at the time of entering the curve, and the driver can travel along the curve with a comfortable operation feeling corresponding to the degree of curve curvature.

  As described above, according to the EPS system 16 of the vehicle steering assist device 10 according to the first embodiment, it is possible to travel a curve more satisfactorily. That is, when the EPS system 16 receives a factor other than the lateral acceleration G when performing the steering support control for reducing the steering force of the driver as the lateral acceleration G is increased by the lateral acceleration support unit 72, the EPS system 16 reduces the steering support amount. change. Therefore, at the time of turning support based on factors other than the lateral acceleration G, it is possible to perform appropriate steering support by adjusting the excess or deficiency of the steering support amount.

  In addition, the brake system 20 according to the first embodiment distributes the braking force of the left and right wheels 26 based on the steering angle θ, thereby turning the host vehicle 12 with faster responsiveness than the EPS system 16. At this time, the EPS system 16 can suppress the steering from becoming lighter than necessary by setting the steering assist amount based on the corrected lateral acceleration Cg in which the lateral acceleration G has decreased, and can turn with high responsiveness. It is possible to achieve both support and appropriate steering support.

  It should be noted that the configuration of the vehicle steering assist device 10 is not limited to the above configuration, and various modifications and application examples can be taken. For example, as described above, the vehicle steering assistance device 10 not only reduces the steering assistance amount (steering assistance torque) in the turning assistance control of the brake system 20, but also responds to various turning assistances by the host vehicle 12 during turning. The steering assist amount can be changed.

  As a modification, if the host vehicle 12 has a structure in which the left and right wheels 26 are driven by different power sources (a two-motor mechanism of a right motor and a left motor), the driving force distribution of the left and right power sources in the curve is different. By making it, turning property can be improved. Even when this driving force distribution is performed, the vehicle steering assist device 10 can change the steering assist amount by estimating the yaw moment and correcting the lateral acceleration G. As a result, the driver's steering force can be appropriately reduced to provide a comfortable operational feeling.

[First application example]
The vehicle steering assist device 10A according to the first application example is configured to perform appropriate steering assist control even when avoiding the preceding other vehicle 100 (obstacle) when traveling on a curve as shown in FIG. 7A. Has been. Note that the vehicle steering assist device 10 </ b> A can directly perform the steering assist control of the EPS system 16 and the turning assist control of the brake system 20 according to the first embodiment when traveling on a curve.

  As shown in FIG. 8, the EPS system 16 </ b> A of the vehicle steering assist device 10 </ b> A includes information on the imaging processing system 50 and information on the navigation device 52 in addition to the detection signals of the torque sensor 32, the vehicle speed sensor 40, and the steering angle sensor 30. It is configured to receive and process. The image processing ECU 48 of the imaging processing system 50 includes an obstacle extraction unit 82 (obstacle acquisition unit) and an overlap as a functional unit that processes image information in front of the traveling direction of the host vehicle 12 captured by the camera 44 and the radar 46. An amount calculation unit 84 (overlap amount acquisition means).

  The obstacle extracting unit 82 extracts the other vehicle 100 traveling on the traveling road from the image information acquired by the camera 44 and the radar 46. This extraction method is not particularly limited, and a known process for detecting an obstacle from image information may be used as it is in order to avoid a collision between the host vehicle 12 and the obstacle. The obstacles extracted by the obstacle extraction unit 82 include various objects such as people and animals in addition to the other vehicle 100.

  The overlap amount calculation unit 84 calculates the overlap amount OL between the other vehicle 100 extracted by the obstacle extraction unit 82 and the host vehicle 12. As shown in FIG. 7B, the overlap amount OL means the axle A that virtually extends linearly in the traveling direction of the host vehicle 12 from the center in the width direction of the host vehicle 12 and the center in the width direction of the rear portion of the other vehicle 100. Difference in the width direction with respect to the portion (deviation amount). Therefore, for example, when the overlap amount OL is large outside the turning direction of the host vehicle 12 in a curve, it can be considered that the other vehicle 100 preceding the own vehicle 12 is traveling closer to the outside in the turning direction. The overlap amount calculation unit 84 outputs the calculated overlap amount OL to the EPS system 16.

  As shown in FIG. 8, the lateral acceleration support unit 72A of the EPS system 16A includes a curve determination unit 86, a corrected lateral acceleration adjustment, in addition to the generated yaw moment estimation unit 76, the addition unit 74, and the lateral acceleration support calculation unit 80. Part 88 is provided.

  The curve discriminating unit 86 discriminates that the host vehicle 12 travels a curve based on the detection signal of the sensor group 18. For example, the curve determination unit 86 acquires the current position of the host vehicle 12 and the map information of the travel route from the navigation device 52, and determines that the current position or the front of the host vehicle 12 is located on the curve. . Note that various methods can be used as a method of determining the curve of the traveling road by the curve determining unit 86, for example, a traveling road including a lane from image information acquired by the imaging processing system 50, or a preceding other vehicle. 100 may be detected, and the curve may be determined from the degree of the curve. Alternatively, the curve determination unit 86 may be configured to determine a curve based on the lateral acceleration G, the steering angle θ, the vehicle speed V, the actual yaw rate Yr, and the like.

  The corrected lateral acceleration adjustment unit 88 adjusts the corrected lateral acceleration Cg based on the overlap amount OL calculated by the overlap amount calculation unit 84 of the imaging processing system 50. Specifically, the corrected lateral acceleration adjustment unit 88 decreases the correction amount of the corrected lateral acceleration Cg as the overlap amount OL increases toward the inside in the turning direction. That is, the corrected lateral acceleration Cg obtained by reducing the lateral acceleration G of the lateral acceleration sensor 38 is increased moderately in proportion to the overlap amount OL. Then, the corrected lateral acceleration adjustment unit 88 outputs the increased lateral acceleration Cg after correction (the correction amount is reduced) to the lateral acceleration support calculation unit 80. The corrected lateral acceleration adjusting unit 88 is provided between the generated yaw moment estimating unit 76 and the adding unit 74, and may be adjusted to reduce the estimated yaw moment output from the generated yaw moment estimating unit 76. .

  The lateral acceleration support calculation unit 80 calculates a steering support torque (amount of current supplied to the EPS motor 36) based on the corrected lateral acceleration Cg having a small correction amount. The EPS system 16A assists the driver's turning when traveling on a curve by applying a driving force based on the calculation of the EPS_ECU 34A to the steering mechanism 28.

  That is, when the vehicle travels on a curve, the other vehicle 100 is closer to the inner side of the travel path as the overlap amount OL between the host vehicle 12 and the other vehicle 100 increases toward the inside in the turning direction. Therefore, as shown in FIG. 7A, by assisting to reduce the turning of the own vehicle 12 to the inside in the turning direction, the own vehicle 12 can be easily directed to the inner traveling path (see FIG. 7A). 7A), the other vehicle 100 can be smoothly avoided. Note that the vehicle steering assist device 10A stops the operation of the corrected lateral acceleration adjustment unit 88 when the imaging processing system 50 or the navigation device 52 detects that there is no travel path inside the turning direction of the host vehicle 12. May be. Thereby, the corrected lateral acceleration Cg is sent as it is to the lateral acceleration assist calculation unit 80, and the steering of the steering wheel 14 in a direction where there is no traveling path remains heavy, so that the host vehicle 12 travels well on the curve. Can do.

  As described above, in the vehicle steering assist device 10A according to the first application example, when the own vehicle 12 overlaps the other vehicle 100 on the inner side in the turning direction, it is based on the braking force of the turning support control of the brake system 20. The correction amount of the lateral acceleration G is reduced. Therefore, it is possible to increase the steering assist amount to the inside in the turning direction that is easy to avoid the other vehicle 100 during the curve traveling, and to improve the avoidance performance of the other vehicle 100. When the overlap amount OL between the host vehicle 12 and the other vehicle 100 increases toward the inside in the turning direction, the vehicle steering assist device 10A determines that the host vehicle 12 as shown by the two-dot chain line arrow in FIG. 7B. In order to avoid this, the steering assist control by the lateral acceleration G may be stopped or reduced.

[Second application example]
As shown in FIGS. 9A and 9B, the vehicle steering assist device 10B according to the second application example is suitable even when traveling on a cant road Ca where the traveling road surface of the curve becomes lower from the inside in the turning direction toward the outside. It is comprised so that steering assistance control may be implemented.

  As shown in FIG. 10, the vehicle steering assist device 10 </ b> B includes a road surface inclination calculation unit 90 (road surface inclination acquisition means, environment acquisition means) that calculates the degree of inclination of the traveling road surface. The application target of the road surface inclination calculation unit 90 is not particularly limited, and can be provided in, for example, a vehicle control ECU (not shown), an ESC device 60 that detects and controls the behavior of the vehicle, and the like. Alternatively, the road surface inclination calculating unit 90 may be constructed in the EPS_ECU 34B.

  The road surface inclination calculation unit 90 calculates the inclination degree of the cant road Ca based on the steering angle θ of the steering angle sensor 30. For example, when the host vehicle 12 travels on the cant road Ca, as shown in FIG. 9A, the host vehicle 12 is guided to the outside in the turning direction in which the host vehicle 12 flows unilaterally. It is assumed that the steering is repeatedly performed by turning the handle 14 inward in the turning direction. For this reason, the road surface inclination calculation part 90 can discriminate | determine the driving | running | working of cant road Ca based on the waveform change of steering angle (theta). Further, when the inclination of the cant road Ca is large, the amplitude of the steering angle θ is increased, and therefore, the inclination degree of the cant road Ca can be calculated according to the amplitude.

  In addition, calculation of the inclination degree of cant road Ca by the road surface inclination calculation part 90 is not limited to the said method, A various method can be taken. For example, the road surface inclination calculation unit 90 may correct the degree of inclination of the cant road Ca based on the actual yaw rate Yr of the host vehicle 12. Further, for example, the vehicle steering assist device 10 may mount the inclination sensor 92 on the host vehicle 12 and calculate the degree of inclination of the cant road Ca from the detection value of the inclination sensor 92. The tilt sensor 92 may be configured integrally with the lateral acceleration sensor 38 as a three-axis acceleration sensor. Further, when the information on the cant road Ca exists in the navigation device 52, the road surface inclination calculation unit 90 may obtain information from the navigation device 52.

  On the other hand, the lateral acceleration support unit 72B of the EPS_ECU 34B includes a generated yaw moment estimation unit 76, a calculation unit 78, a lateral acceleration support calculation unit 80, a curve determination unit 86, and a corrected lateral acceleration adjustment unit 88, as in the first application example. I have. The inclination degree of the cant road Ca calculated by the road surface inclination calculation unit 90 is input to the corrected lateral acceleration adjustment unit 88.

  The corrected lateral acceleration adjustment unit 88 increases the correction amount of the corrected lateral acceleration Cg as the inclination degree of the cant road Ca increases (in other words, the cant road Ca becomes lower from the inner side to the outer side in the width direction). Make it smaller. That is, the corrected lateral acceleration Cg that decreases the lateral acceleration G of the lateral acceleration sensor 38 is increased in proportion to the degree of inclination. Then, the corrected lateral acceleration adjusting unit 88 outputs the adjusted corrected lateral acceleration Cg to the lateral acceleration support calculating unit 80.

  As a result, the lateral acceleration support calculation unit 80 calculates the steering support torque based on the corrected lateral acceleration Cg with a small correction amount, and the EPS system 16B applies the driving force according to the calculation result to obtain the curve. Assists the driver to steer when driving. Therefore, as shown by the solid line arrow in FIG. 9B, the vehicle steering assist device 10B performs control to lighten the turning to the inside in the turning direction by the driver, and the driver holds the vehicle 12 inside. Can easily be directed to the driving path.

  As described above, the EPS system 16B of the vehicle steering assistance device 10B according to the second application example determines the correction amount of the lateral acceleration G based on the braking force of the turning assistance of the brake system 20 according to the degree of inclination of the cant road Ca. Make it smaller. That is, when the inclination of the cant road Ca increases, steering assistance is required toward the inside of the turning direction. Therefore, the vehicle steering assistance device 10B increases the steering assistance amount toward the inside of the turning direction, thereby Good steering can be performed even during traveling.

[Second Embodiment]
As shown in FIGS. 11A and 11B, the vehicle steering assist device 10C according to the second embodiment has another vehicle (obstacle) between the preceding other vehicle and the host vehicle 12 during the CC control. Even if it is interrupted, it is configured to perform appropriate steering support control. Hereinafter, the other vehicle that precedes the travel path is referred to as a first other vehicle 102, and the other vehicle that enters the travel path is referred to as a second other vehicle 104.

  In the CC control, the vehicle steering assist device 10C follows the first other vehicle 102 and travels on the traveling road as indicated by a one-point difference line in FIG. 11A. When the vehicle travels on a curve, the driver steers the steering mechanism 28 inward in the turning direction, and the EPS system 16C maintains the steering angle θ as steering assist control (that is, the steering angle shown in FIG. 2B). The state is the stop point St).

  At this time, as shown in FIG. 12, the vehicle steering assist device 10 </ b> C has a lane detection unit 94 (lane detection unit) and an obstacle extraction unit 82 (obstacle acquisition unit) built in the image processing ECU 48. The lane detection unit 94 detects the lane of the traveling road based on the image information acquired by the camera 44 and the radar 46. The obstacle extraction unit 82 has the same configuration as that of the first application example, and detects a plurality of other vehicles (first and second other vehicles 102 and 104) traveling in front of the traveling path based on the image information.

  The EPS system 16C adjusts (steers) the steering angle θ of the steering mechanism 28 so that the host vehicle 12 follows the first other vehicle 102 detected by the imaging processing system 50. When the second other vehicle 104 has interrupted during the CC control, the driver performs a response to move the host vehicle 12 to another travel path in order to avoid proximity to the second other vehicle 104 in addition to decelerating. There is a possibility to try.

  For this reason, the EPS system 16C includes an obstacle interrupt determination unit 96 in the EPS_ECU 34C. The obstacle interruption determination unit 96 determines whether or not the second other vehicle 104 has entered the travel path on which the host vehicle 12 is traveling. The determination method by the obstacle interrupt determination unit 96 is not particularly limited. For example, the second other vehicle 104 is continuously detected from the obstacle extraction unit 82 and the movement vector of the second other vehicle 104 is calculated. Then, it is determined that the second other vehicle 104 interrupts the travel path of the host vehicle 12. The determination result of the obstacle interrupt determination unit 96 is output to the lateral acceleration support unit 72.

  When the lateral acceleration support unit 72 obtains the interrupt determination result of the second other vehicle 104 from the obstacle interrupt determination unit 96, the lateral acceleration support unit 72 gradually decreases the steering support torque (steering force of the steering mechanism 28). That is, when turning for avoiding based on the interruption of the second other vehicle 104 while driving on the curve, the steering mechanism 28 is held by the steering assist control. There is a possibility that a feeling of left-right difference or a feeling of sticking may be felt. Therefore, the vehicle steering assist device 10C gradually reduces the steering assist torque of the steering mechanism 28 when the second other vehicle 104 is determined to be interrupted, in other words, fades out the steering assist control, thereby making the driver feel uncomfortable. No operation can be realized.

  As shown in FIG. 11B, when the second other vehicle 104 has entered the travel path of the host vehicle 12 during the CC control, the steering of the steering mechanism 28 by the EPS system 16C is reduced. Accordingly, the steering wheel 14 is in a free state, and the driver can easily steer the steering wheel 14 to avoid the second other vehicle 104 so as to move the host vehicle 12 to the traveling path on the inner side in the turning direction, for example. it can. Note that the steering assist torque of the basic support unit 70 is received when the steering wheel 14 is steered.

  As described above, the EPS system 16 </ b> C of the vehicle steering assist device 10 </ b> C according to the second embodiment has a steering assist amount (of the steering mechanism 28) when the second other vehicle 104 enters the travel path of the host vehicle 12. By reducing the (steering force), it is possible to reduce the uncomfortable feeling of the avoidance operation. That is, by performing the steering assist control based on the lateral acceleration G while driving on a curve, there is a possibility that the driver's steering of the steering wheel 14 may give a sense of incongruity such as a left / right difference or a feeling of sticking. By reducing the number, the uncomfortable feeling of the avoidance operation can be reduced.

  Note that the vehicle steering assist device 10C may adjust the reduction amount of the steering assist control according to the overlap of the second other vehicle 104, like the vehicle steering assist device 10A according to the first application example.

  Further, the EPS system 16C may change the steering assistance torque (steering assistance amount) when determining the interruption of the second other vehicle 104, and may perform control other than the fade-out of the steering assistance control. For example, in order to improve the avoidance operation of the host vehicle 12, the steering assist torque may be increased so as to lighten the steering of the handle 14 inward in the turning direction by the driver. Alternatively, the EPS system 16 </ b> C may not only gradually decrease the steering assist control but also immediately stop when determining the interruption of the second other vehicle 104.

  Further, the fade-out of the steering assist control by the vehicle steering assist device 10C according to the second embodiment is not limited to the time when the CC control is performed. For example, even if the CC control is not performed, if the EPS system 16C keeps the rudder angle θ when traveling on a curve, the steering assist control is faded out when the second other vehicle 104 is determined to be interrupted. The traveling direction of the host vehicle 12 can be easily changed.

[Third Embodiment]
As shown in FIGS. 13A and 13B, the vehicle steering assist device 10D according to the third embodiment performs appropriate steering even when the host vehicle 12 generates oversteer that is too curved or understeer that cannot bend the curve. It is configured to perform support control. For example, when the road surface is a low μ road surface (low friction road surface) due to a snow road or freezing, the grip of the wheel 26 easily reaches the limit on the road surface, and oversteer or understeer occurs. . When oversteer or understeer occurs, the driver takes measures such as countersteering and steering wheel return.

  Therefore, the EPS system 16D of the vehicle steering assistance device 10D is configured to stop or reduce the steering assistance control so that countersteering and steering wheel return are not hindered when oversteering or understeering occurs. As shown in FIG. 14, the EPS_ECU 34D constructs the own vehicle state determination unit 98, receives the actual yaw rate Yr from the yaw rate sensor 42 (actual yaw rate acquisition means), and receives the reference yaw rate Yc from the ESC_ECU 62 (reference yaw rate acquisition means). Receive. As described above, the standard yaw rate Yc is appropriately calculated based on the steering angle θ and the vehicle speed V.

  Based on the acquired actual yaw rate Yr and the reference yaw rate Yc, the host vehicle state determination unit 98 determines neutral steer in which the host vehicle 12 is in a normal state and oversteer or understeer in an abnormal state. That is, when the difference between the actual yaw rate Yr and the reference yaw rate Yc is larger or smaller than a predetermined value, it can be said that the vehicle is in an oversteer or understeer state. The determination result of the own vehicle state determination unit 98 is output to the lateral acceleration support unit 72.

  When the lateral acceleration support unit 72 receives the determination result of oversteer or understeer from the own vehicle state determination unit 98, the lateral acceleration support unit 72 stops the steering support torque (the steering holding force of the steering mechanism 28). That is, the driver can smoothly perform a steering operation such as counter-steering or steering wheel return by stopping the steering assist control when oversteering or understeering occurs while the vehicle is traveling on a curve. Thereby, the behavior of the own vehicle 12 can be stabilized at an early stage.

  As described above, the EPS system 16D of the vehicle steering assist device 10D according to the third embodiment stops the steering assist control when the difference between the standard yaw rate Yc and the actual yaw rate Yr is equal to or larger than a predetermined value (to 0). To do). Therefore, when the host vehicle 12 is oversteered or understeered on a low μ road surface such as a snowy road or a freezing road, it is possible to prevent the steering assist control from being performed to the incision side, and the traveling stability of the host vehicle 12 can be prevented. Can be increased. Note that the vehicle steering assist device 10D makes it easier for the driver to steer even when the difference between the standard yaw rate Yc and the actual yaw rate Yr is greater than or equal to a predetermined value, even if the steering assist control is reduced from the normal state. Can do.

  The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10, 10A-10D ... Vehicle steering assistance apparatus 12 ... Own vehicle 16, 16A-16D ... Electric power steering system (EPS system)
DESCRIPTION OF SYMBOLS 20 ... Brake system 30 ... Steering angle sensor 34, 34A-34D ... EPS electronic control unit (EPS_ECU)
36 ... EPS motor 38 ... Lateral acceleration sensor 42 ... Yaw rate sensor 50 ... Imaging processing system 62 ... ESC_ECU 72, 72A, 72B ... Lateral acceleration support unit 76 ... Generated yaw moment estimation unit 78 ... Calculation unit 80 ... Lateral acceleration support calculation unit 82 ... obstacle extraction unit 84 ... overlap amount calculation unit 88 ... corrected lateral acceleration adjustment unit 90 ... road surface inclination calculation unit 94 ... lane detection unit Cg ... corrected lateral acceleration G ... lateral acceleration Yc ... standard yaw rate Yr ... actual yaw rate θ: Rudder angle

Claims (6)

Lateral acceleration acquisition means for acquiring the lateral acceleration of the host vehicle;
A vehicle steering assist device comprising: a first steering assist unit that performs control to increase a steering assist amount that reduces a driver's steering force as the lateral acceleration acquired by the lateral acceleration acquisition unit increases.
Having at least one of second steering support means for supporting turning of the host vehicle by control different from the first steering support means, and environment acquisition means for acquiring environment information of the host vehicle;
The vehicle steering support device, wherein the first steering support means changes the steering support amount based on the turning support by the second steering support means or the environment information of the environment acquisition means. The vehicle steering assist device according to claim 1, wherein
Rudder angle obtaining means for obtaining the rudder angle of the host vehicle,
The second steering support means generates a turning amount of the host vehicle by allocating driving force or braking force of the left and right wheels of the host vehicle based on the steering angle acquired by the steering angle acquiring unit as the turning support. Let
The first steering support means acquires the turning amount generated by the second steering support means, and the corrected lateral acceleration that decreases the lateral acceleration acquired by the lateral acceleration acquisition means as the turning amount increases. And the steering assistance amount is set based on the corrected lateral acceleration. The vehicle steering assist device according to claim 2, wherein
The environment acquisition means includes
Obstacle acquisition means for acquiring an obstacle ahead of the traveling direction of the host vehicle;
An overlap amount acquisition means for acquiring an overlap amount in the vehicle width direction between the obstacle detected by the obstacle acquisition means and the host vehicle,
The first steering assist means decreases the correction amount of the lateral acceleration based on the turning amount of the second steering assist means as the overlap amount of the overlap amount acquisition means increases inward in the turning direction. A vehicle steering assist device. In the vehicle steering assistance device according to claim 2 or 3,
The environment acquisition means includes road surface inclination acquisition means for acquiring the degree of inclination in the width direction of the traveling road surface of the host vehicle,
The lateral acceleration based on the turning amount of the second steering assist means increases as the degree of inclination of the first steering assist means decreases from the inner side to the outer side in the width direction of the traveling road surface by the road surface inclination acquisition means. A vehicle steering assist device characterized in that the correction amount of the vehicle is reduced. The vehicle steering assist device according to claim 1, wherein
The environment acquisition means includes
Lane detection means for detecting the lane of the traveling path of the host vehicle;
Obstacle acquisition means for acquiring an obstacle ahead of the traveling direction of the host vehicle,
The first steering assistance means reduces the steering assistance amount when the obstacle enters the traveling path of the host vehicle in front of the host vehicle by the lane detection unit and the obstacle acquisition unit. A vehicle steering assist device characterized in that it is set to zero. The vehicle steering assist device according to claim 1, wherein
Rudder angle obtaining means for obtaining the rudder angle of the host vehicle,
The environment acquisition means includes
Normative yaw rate acquisition means for acquiring a reference yaw rate based on at least the rudder angle acquired by the rudder angle acquisition means;
An actual yaw rate acquisition means for acquiring an actual yaw rate actually generated in the host vehicle,
The vehicle steering assist device, wherein the first steering assist means reduces or reduces the steering assist amount when a difference between the reference yaw rate and the actual yaw rate becomes a predetermined value or more.

Images