JP5416442B2 - Suspension control device - Google Patents

Description

  The present invention relates to a suspension control apparatus for controlling a suspension of a vehicle such as an automobile, and more particularly to an apparatus that improves ease of driving when entering a curved road.

A suspension device for an automobile includes a spring and a damper (shock absorber) provided between an upper side of a spring such as a vehicle body and a lower side of a spring such as a suspension arm and a hub bearing housing. The damper generally generates a damping force corresponding to the piston speed during the suspension stroke by using oil flow resistance.
As such a damper, a variable damping force type in which the damping force can be changed during traveling is known.

  For example, in Patent Document 1, a shock absorber that can change the orifice opening area through which damper oil passes by a valve driven by a stepping motor and the damping force characteristic can be changed is used. A vehicle suspension device is described in which the damping force is controlled so that the phase difference is within ¼ period.

JP 2007-313951 A

However, from the viewpoint of optimizing the response of the vehicle body to the driving operation when entering the curve, the responsiveness of the pitch to the driver's steering operation (steering operation) is more important than the phase difference between the roll and the pitch.
For example, in the case of a vehicle having a high center of gravity position such as a sports utility vehicle, the roll delay with respect to the steering operation is large, and even if the phase of the pitch is adjusted to this delayed roll, The pitch is delayed with respect to the steering operation, making it difficult for the driver to drive the vehicle.

On the other hand, it is known that the driver's line of sight shifts the line of sight to a target inside the curve such as a white line, for example, in accordance with the curve approach of the host vehicle. At this time, it is considered that the driver often moves the line of sight downward because the driver checks the lateral position in the lane of the vehicle using a target that is relatively close to the vehicle (for example, a white line in the vicinity of the vehicle). .
Therefore, it is considered that if the pitching that falls forward is generated in the vehicle body when entering the curve, the downward line-of-sight movement of the driver can be appropriately compensated, and the ease of driving the vehicle can be improved.
An object of the present invention is to provide a suspension control device that optimizes the responsiveness of pitching to a steering operation and improves the ease of driving.

The present invention solves the above-described problems by the following means.
The invention according to claim 1 is a suspension control device for controlling a suspension in accordance with a steering operation of a driver, a steering wheel angular velocity detecting means for detecting an angular velocity of a steering wheel angle, and a damping force control coefficient set based on the angular velocity. The damping force of at least the rebound side of the front wheel inner ring side damper and the damping force of at least the bump side of the rear wheel outer ring side damper are increased according to the increase in the front wheel inner ring side damper, and the damping force of the front wheel outer ring side damper and the rear wheel inner ring side damper is increased. Damper damping force setting means for maintaining or reducing the damping force , and the damper damping force setting means increases the damping force control coefficient in accordance with an increase in a value obtained by performing a phase advance process on the angular velocity. The suspension control device is characterized.
In the present specification, claims, and the like, the inner ring side and the outer ring side indicate the side closer to the turning center and the far side in the turning radius direction, respectively.

According to a second aspect of the present invention, there is provided traveling path recognition means for detecting a traveling path curvature in front of the host vehicle, and the damper damping force setting means increases the damping force control coefficient in accordance with an increase in the traveling path curvature. The suspension control device according to claim 1 .
According to a third aspect of the present invention, there is provided a suspension control device for controlling a suspension in accordance with a steering operation of a driver, a steering wheel angular velocity detecting means for detecting an angular velocity of a steering wheel angle, and a damping force control coefficient set based on the angular velocity. The damping force of at least the rebound side of the front wheel inner ring side damper and the damping force of at least the bump side of the rear wheel outer ring side damper are increased according to the increase in the front wheel inner ring side damper, and the damping force of the front wheel outer ring side damper and the rear wheel inner ring side damper is increased. A damper damping force setting means for maintaining or reducing the driving force, and a traveling path recognition means for detecting a traveling road curvature in front of the host vehicle, wherein the damper damping force setting means controls the damping force control according to an increase in the traveling road curvature. A suspension control apparatus characterized by increasing a coefficient .

According to the present invention, the following effects can be obtained.
(1) The damping force on at least the rebound side of the front wheel inner ring side damper and the damping force on at least the bump side of the rear wheel outer ring side damper are increased according to an increase in the damping force control coefficient set based on the angular velocity of the steering wheel angle. By increasing this, when rolls are generated due to lateral acceleration during turning, the front wheel inner wheel side suspension is restrained from being stretched, and the front wheel outer wheel side suspension is contracted to lower the vehicle body forward. Therefore, the vehicle body can be raised rearward by the expansion of the rear wheel inner ring side suspension. As a result, pitching in the direction in which the vehicle body is nose dive can be generated simultaneously with the occurrence of lateral acceleration, which compensates for the downward movement of the driver's line of sight and facilitates the visual recognition of lateral targets such as white lines. Ease of driving can be improved.
(2) By increasing the damping force control coefficient in accordance with an increase in the value obtained by performing the phase advance processing on the steering wheel angular velocity, the above-described pitch moment delay in the nose dive direction with respect to the steering wheel angular velocity is compensated, and the vehicle It is possible to further improve the ease of driving. As a process for advancing the phase, for example, a known high-pass filter process can be performed.
(3) By increasing the damping force control coefficient in accordance with an increase in the travel path curvature, it is possible to obtain an appropriate pitching amount according to the magnitude of the curvature. In the case of a straight road with substantially zero curvature, the vehicle body posture can be stabilized by not generating pitching.

1 is a diagram showing a system configuration of a vehicle including an embodiment of a suspension control device to which the present invention is applied. It is a figure which shows the structure of the damper damping force adjustment mechanism in the vehicle of FIG. It is a flowchart which shows the damper damping force control in the vehicle of FIG. 2 is a graph showing a correlation between a steering angular velocity advance processing value and a damping force control coefficient in the vehicle of FIG. 1. It is a graph which shows the damping-force characteristic of the damper in the vehicle of FIG.

  An object of the present invention is to provide a suspension control device that optimizes the responsiveness of pitching with respect to steering operation and improves the ease of driving. The problem was solved by increasing the damping force of the rear-wheel outer-wheel damper and generating pitching that descends simultaneously with lateral acceleration.

Embodiments of a suspension control apparatus to which the present invention is applied will be described below.
The suspension control device according to the embodiment is provided in, for example, a four-wheeled vehicle such as a passenger car that steers the two front wheels.
FIG. 1 is a diagram illustrating a system configuration of a vehicle including a suspension control device according to an embodiment. This suspension control device changes the damping force of each damper according to the steering operation of the driver.

  The vehicle includes a steering mechanism 10, an electric power steering (EPS) control unit 20, a steering control unit 30, an engine control unit 40, a transmission control unit 50, a travel path recognition unit 60, a vehicle integration unit 70, a damper control unit 100, a damper. FL120, damper FR130, damper RL140, damper RR150, etc. are provided.

The steering mechanism 10 performs steering by rotating the housing H that supports the front wheels FW about a predetermined steering axis.
The steering mechanism 10 includes a steering wheel 11, a steering shaft 12, a steering gear box 13, a tie rod 14, and the like.
The steering wheel 11 is an annular operation member through which a driver inputs a steering operation.
The steering shaft 12 is a rotating shaft that transmits the rotation of the steering wheel 11 to the steering gear box 13.
The steering gear box 13 includes a rack and pinion mechanism that converts the rotational movement of the steering shaft 12 into a straight movement in the vehicle width direction.
The tie rod 14 is a shaft-like member having one end connected to the rack of the steering gear box 13 and the other end connected to the knuckle arm of the housing H. The tie rod 14 steers by rotating the housing H by pushing and pulling the knuckle arm of the housing H.

The EPS control unit 20 comprehensively controls an electric power steering device that generates a steering assist force in accordance with a driver's steering operation. The EPS control unit 20 is connected to an electric actuator (ACT) 21, a torque sensor 22, and the like.
The electric actuator (ACT) 21 is, for example, an electric motor that is provided in the middle of the steering shaft 12 and applies a steering torque (steering force) to the steering mechanism 10 via a speed reduction mechanism.
The torque sensor 22 is inserted into the steering shaft 12 between the electric actuator (ACT) 21 and the steering wheel 11 and detects torque acting on the steering shaft 12. Normally, the torque detected by the torque sensor 22 is substantially equal to the steering torque input to the steering wheel 11 by the driver.

The steering control unit 30 performs vehicle steering control and ABS control for individually controlling the braking force of each wheel brake. In vehicle stability control, when understeer or oversteer occurs, the braking force on the turning inner wheel side and the outer wheel side is made different to generate a yaw moment in the restoring direction. ABS control (anti-lock brake control) is for reducing and recovering the braking force of a wheel when the tendency of the wheel to lock is detected.
The steering control unit 30 is connected to a hydraulic control unit (HCU) 31, a vehicle speed sensor 32, a yaw rate sensor 33, a lateral acceleration (lateral G) sensor 34, and the like.

The HCU 31 is a device that individually controls the brake fluid hydraulic pressure applied to the hydraulic service brake of each wheel. The HCU 31 includes a motor pump that pressurizes the brake fluid, a solenoid valve that adjusts the pressure applied to the caliper cylinder of each wheel, and the like.
The vehicle speed sensor 32 is provided in a housing that holds the hub bearing of each wheel, and outputs a vehicle speed pulse signal corresponding to the wheel speed. The vehicle speed pulse signal is subjected to predetermined processing, whereby the traveling speed of the vehicle can be obtained.
The yaw rate sensor 33 and the lateral G sensor 34 include a MEMS sensor that detects a rotational speed around the vertical axis of the vehicle body and a lateral acceleration, respectively.

The engine control unit 40 controls the engine, which is a driving power source for the vehicle, and its auxiliary equipment.
The transmission control unit 50 controls the automatic transmission that shifts the output of the engine and transmits it to the front and rear differentials.

The travel path recognition unit 60 recognizes the curve curvature of the travel path ahead of the host vehicle. The travel path recognition unit 60 includes a stereo camera (CAM) 61, an image processing unit 62, a travel path recognition means 63, and the like.
The stereo camera (CAM) 61 includes, for example, a pair of main cameras and sub cameras provided in the vicinity of a room mirror base at the upper end of the front window of the vehicle. Each of the main camera and the sub camera has a CCD camera. The main camera and the sub camera are installed apart from each other in the vehicle width direction. The main camera and the sub camera capture a reference image and a comparative image, respectively, and output image data related to these images to the image processing unit 62.

  The image processing unit 62 performs A / D conversion on the image data of the reference image and the comparison image output from the stereo camera (CAM) 61, performs predetermined image processing, and outputs the result to the travel path recognition unit 63. This image processing includes, for example, correction of an attachment position error of each camera, noise removal, gradation optimization, and the like. The digitized image has, for example, a plurality of pixels arranged in a matrix in the vertical direction and the horizontal direction. Each of these pixels has a luminance value corresponding to the brightness of the subject.

  The travel path recognition unit 63 detects parallax of a pixel group that is a block composed of an arbitrary pixel or a plurality of pixels on the reference image based on the data of the reference image and the comparison image. This parallax is the amount of deviation between the position on the reference image and the position on the comparison image of a certain pixel or pixel group. Using this parallax, the distance from the vehicle to the subject corresponding to the pixel can be calculated based on the principle of triangulation.

Moreover, the travel path recognition means 63 recognizes the shape of the white line etc. which are arrange | positioned at the lane both ends ahead of the own vehicle.
The travel path recognition unit 63 detects a pixel group of the white line portion based on the luminance data of the pixel from the reference image data. The orientation of the pixel group of the white line portion with respect to the host vehicle is detected based on the pixel position on the image data. Specifically, an area corresponding to a pixel position in the vertical direction on the road surface is scanned in the horizontal direction, and a portion where the luminance value changes suddenly is recognized as a lane outline. Then, the position of the white line is detected by calculating the distance of the pixel group in the white line portion.
The travel path recognition means 63 continuously detects the position of the white line to set a plurality of lane candidate points in the traveling direction of the vehicle, ignores the lane candidate points that cannot be matched, and sets the lane candidate points. The area that could not be recognized is recognized as a lane shape ahead of the host vehicle by performing a predetermined complement process. The lane shape recognized here includes the presence or absence of a curve and the curvature of the curve.

  The vehicle integration unit 70 controls the electrical components of the vehicle other than those related to each unit.

The damper control unit 100 is a suspension control device according to the present invention, and controls the damping force of the dampers 120 to 150 of the suspension of each wheel according to the steering operation of the driver.
In addition, each unit mentioned above including the damper control unit 100 is connected by vehicle-mounted LAN, such as a CAN communication system, for example, and communication is possible.
The damper control unit 100 includes a steering angle calculation unit 101, an angular velocity calculation unit 102, a high-pass filter (HPF) 103, a damper damping force setting unit 104, a damper damping force control unit 105, and the like.

The steering angle calculation means 101 calculates a steering wheel angle (steer angle) of the steering mechanism 10 by a driver's steering operation. A steering angle sensor 101 a is connected to the steering angle calculation means 101.
The steering angle sensor 101a includes an encoder that is provided on the steering shaft 12 and detects an angular position thereof (substantially equal to the angular position of the steering wheel 11). The steering angle calculation means 101 calculates the steering wheel angle based on the output of the steering angle sensor 101a.

The angular velocity calculating means 102 is for differentiating the steering wheel angle calculated by the steering angle calculating means 101 to calculate the angular velocity of the steering wheel angle (hereinafter referred to as “steering wheel angular velocity”).
The angular velocity calculation means 102 functions as the steering wheel angular velocity detection means according to the present invention in cooperation with the steering angle calculation means 101 described above.

The high-pass filter 103 performs high-pass filter processing shown in the following equation 1 on the steering wheel angular velocity calculated by the angular velocity calculating means 102, and calculates a steering angular velocity advance processing value.

The damper damping force setting means 104 sets a damping force control coefficient K based on the steering angular velocity advance processing value output from the high pass filter 103, and a target damping force based on the damping force control coefficient K and a predetermined reference damping force. Is set.
The damper damping force control means 105 controls the damping force of the damper FL120, the damper FR130, the damper RL140, and the damper RR150 based on the target damping force set by the damper damping force setting means 104.
The setting of the damping force control coefficient K, the target damping force and the damping force control of each damper described above will be described in detail later.

  The damper FL120, the damper FR130, the damper RL140, and the damper RR150 are variable damping force type shock absorbers provided on the suspension of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, respectively. Each damper has a tube and a piston that are relatively displaced according to the stroke of the suspension, and generates a damping force according to the piston speed using the flow resistance of the oil enclosed in the tube.

FIG. 2 is a diagram illustrating a configuration of a damping force adjusting mechanism provided in the damper FR120. Other dampers are also provided with substantially the same damping force adjusting mechanism.
The damper FR 120 is provided in parallel with the spring S between the vehicle body B and the wheels W.
The damper FR 120 includes an actuator 121 and a drive circuit 122.
The actuator 121 is an actuator such as a stepping motor that drives an oil passage switching valve provided in the damper FR 120 and changes the damping force characteristic of the damper FR 120.
The drive circuit 122 supplies electric power to the actuator 121 in accordance with a control signal from the damper damping force control means 105 of the damper control unit 100 to change the damping force characteristic.

FIG. 3 is a flowchart showing the damping force control in this embodiment. Hereinafter, the steps will be described step by step.
<Step S01: Handle angle calculation>
The steering angle calculation means 101 calculates the current steering wheel angle (the angular positions of the steering wheel 11 and the steering shaft 12) based on the output of the steering angle sensor 101a.
Thereafter, the process proceeds to step S02.

<Step S02: Steering wheel angular velocity calculation>
The angular velocity calculating means 102 calculates the steering wheel angular velocity by differentiating the steering wheel angle output from the steering angle calculating means 101 with respect to time.
Thereafter, the process proceeds to step S03.

<Step S03: Steering wheel angular velocity HPF process>
The high-pass filter 103 performs the high-pass filter processing according to the above-described equation 1 on the steering wheel angular velocity output from the angular velocity calculating unit 102, and calculates the steering angular velocity advance processing value.
Thereafter, the process proceeds to step S04.

<Step S04: Each damper target damping force setting>
The damper damping force setting means 104 is based on the steering wheel angular velocity advance processing value output by the HPF and the curve curvature of the traveling road ahead of the host vehicle output by the traveling path recognition unit 60. Set the target damping force.
First, the damper damping force setting means 104 sets the damping force control coefficient K based on the steering angular velocity advance processing value. The damping force control coefficient K is a coefficient indicating the ratio of the target damping force to a predetermined reference damping force, and the target damping force increases with respect to the reference damping amount as the damping force control coefficient K increases.

  FIG. 4 is a graph showing the correlation between the steering angular velocity advance processing value and the damping force control coefficient. In FIG. 4, the horizontal axis indicates the steering wheel angular velocity advance processing value (CCW). The right side of the origin is the area where the handle is cut to the left (counterclockwise), the left is the handle on the right (clockwise) ). The vertical axis indicates the damping force control coefficient.

As shown in FIG. 4, when the steering angular velocity advance processing value is zero, the damping force control coefficient K is 1 for each damper, and the target damping force of the damper matches the reference damping force.
In the region where the steering wheel is cut to the left, the damping force control coefficient K for the left front wheel on the turning inner wheel side and the right rear wheel on the turning outer wheel side increases in proportion to the steering angular velocity advance processing value (absolute value). The rate of increase is set higher for the right rear wheel than for the left front wheel. In this region, the damping force control coefficient K of the other two wheels (the right front wheel and the left rear wheel) remains constant at 1.
On the other hand, in the region where the handle is cut to the right, the damping force control coefficient K for the right front wheel on the turning inner wheel side and the left rear wheel on the turning outer wheel side is proportional to the steering angular velocity advance processing value (absolute value). The rate of increase is set greater for the left rear wheel than for the right front wheel. Further, in this region, the damping force control coefficient K of the other two wheels (the left front wheel and the right rear wheel) remains constant at 1.

  Further, the increase rate of the damping force control coefficient K (the slope of the graph in FIG. 4) with respect to the steering angular velocity advance processing value described above is set to increase in accordance with the increase in the curvature of the curve ahead of the host vehicle. Further, when the traveling road ahead of the host vehicle is a straight line, the damping force control coefficient K is set to 1.

Next, the target damping force of each damper is set according to the damping force control coefficient K described above.
FIG. 5 is a graph showing an example of the damping force characteristic of the damper, where the horizontal axis shows the piston speed and the vertical axis shows the damping force. In FIG. 5, the reference damping force when the damping force control coefficient K is 1 is indicated by a broken line, and an example of the target damping force when the damping force control coefficient K is greater than 1 is indicated by a solid line. This target damping force is set so that the damping force at the same piston speed becomes larger than the reference damping force. That is, target damping force = reference damping force × damping force control coefficient K.
Thereafter, the process proceeds to step S05.

<Step S05: Damping damping force control for each damper>
The damper damping force control means 105 outputs a control signal to the actuator drive circuit of each of the dampers 120 to 150 based on the target damping force set by the damper damping force setting means 104, and the damping force of each of the dampers 120 to 150 is output. Control.
Thereafter, the series of processing is terminated (returned).

According to the embodiment described above, by increasing the damper damping force on the turning inner wheel side on the front wheel side in accordance with the advance processing value of the steering wheel angular velocity, the extension amount of the turning outer wheel side damper with respect to the contraction amount of the turning outer wheel side damper is increased. The vehicle height at the front of the vehicle body can be reduced. Further, by increasing the damper damping force on the turning outer wheel side on the rear wheel side, the amount of shrinkage of the turning outer wheel side damper with respect to the extension amount of the turning inner wheel side damper can be reduced, and the vehicle height at the rear of the vehicle body can be increased. As a result, a pitching moment in the nose dive direction can be applied to the vehicle body simultaneously with the occurrence of the lateral acceleration.
Thereby, the downward line-of-sight movement of the driver at the time of entering the curve can be compensated, and it is easy to visually recognize the target close to the host vehicle, thereby improving the ease of driving the vehicle.

Furthermore, the damping force control of the damper is performed based on the advance processing value obtained by applying high-pass filter processing to the steering wheel angular velocity, thereby compensating for the phase delay compared to the case where the steering wheel angular velocity itself is used and suppressing the generation delay of the pitch moment. Thus, the ease of driving of the vehicle can be further improved.
Further, by changing the damping force control coefficient K in accordance with the curve curvature in front of the host vehicle, an appropriate pitching amount according to the curve curvature can be obtained. For example, when the curvature is large, the pitching amount can be increased to make it easier for the driver to visually recognize a nearby target.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) In the embodiment, the damper damping force is set based on the advance processing value obtained by applying the high-pass filter processing to the steering wheel angular velocity. However, the steering wheel angular velocity is set to a value obtained by advancing the phase by another method or the steering wheel angular velocity. The damper damping force may be set based on this.
(2) The method of adjusting the damper damping force is not limited to the configuration of the above-described embodiment, and can be changed as appropriate. Also, when the damping force on the expansion side (rebound side) and the contraction side (bump side) of the damper can be adjusted independently, only the expansion side damping force is increased on the front wheel inner ring side, and on the rear wheel outer ring side. Only the compression side damping force may be increased. In the embodiment, the damping force of the other two wheels is fixed, but the damping force of the other two wheels may be changed at the same time. For example, the damping force of the front wheel inner wheel side and rear wheel outer wheel side dampers may be increased, and the damping force of the other two-wheel dampers may be decreased.
(3) In the embodiment, the curve curvature in front of the host vehicle is detected by image processing using a stereo camera, but the present invention is not limited to this, and the curve curvature may be detected by other methods. For example, you may use the car navigation apparatus which has the map data accumulate | stored previously, and the own vehicle position positioning means, such as GPS.
(4) Although the steering wheel angular velocity is calculated by differentiating the steering wheel angle in the embodiment, an angular velocity sensor that directly detects the steering wheel angular velocity may be used.

DESCRIPTION OF SYMBOLS 10 Steering mechanism 11 Steering wheel 12 Steering shaft 13 Steering gear box 14 Tie rod H Housing FW Front wheel 20 Electric power steering control unit 21 Electric actuator (ACT)
22 Torque Sensor 30 Operation Control Unit 31 Hydraulic Control Unit 32 Vehicle Speed Sensor 33 Yaw Rate Sensor 34 Lateral Acceleration Sensor 40 Engine Control Unit 50 Transmission Control Unit 60 Traveling Path Recognition Unit 61 Stereo Camera (CAM)
62 Image processing unit 63 Traveling path recognition means 70 Vehicle integration unit 100 Damper control unit 101 Rudder angle calculation means 101a Rudder angle sensor 102 Angular speed calculation means 103 High pass filter 104 Damper damping force setting means 105 Damper damping force control means 120 Damper FL 130 Damper FR
140 Damper RL 150 Damper RR
B Body W Wheel S Spring

Claims (3)

A suspension control device that controls a suspension according to a steering operation of a driver,
Steering wheel angular velocity detection means for detecting the angular velocity of the steering wheel angle;
According to the increase of the damping force control coefficient set based on the angular velocity, the damping force on at least the rebound side of the front wheel inner ring side damper and the damping force on at least the bump side of the rear wheel outer ring side damper are increased, and the front wheel Damper damping force setting means for maintaining or reducing the damping force of the outer ring side damper and the rear wheel inner ring side damper ,
The damper damping force setting means increases the damping force control coefficient in accordance with an increase in a value obtained by performing a phase advance process on the angular velocity.
Suspension control device characterized by this.   A travel path recognition means for detecting a travel path curvature in front of the host vehicle;
  The damper damping force setting means increases the damping force control coefficient in accordance with an increase in the travel path curvature.
  The suspension control device according to claim 1.   A suspension control device that controls a suspension according to a steering operation of a driver,
  Steering wheel angular velocity detection means for detecting the angular velocity of the steering wheel angle;
  According to the increase of the damping force control coefficient set based on the angular velocity, the damping force on at least the rebound side of the front wheel inner ring side damper and the damping force on at least the bump side of the rear wheel outer ring side damper are increased, and the front wheel Damper damping force setting means for maintaining or reducing the damping force of the outer ring side damper and the rear wheel inner ring side damper;
  A travel path recognition means for detecting a travel path curvature in front of the host vehicle;
  The damper damping force setting means increases the damping force control coefficient in accordance with an increase in the travel path curvature.
  Suspension control device characterized by this.

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