JPH11105525A - Suspension control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension control device capable of providing favorable ride comfortableness even in traveling on a protruded road. SOLUTION: In traveling on a wavy road and a protruded road, vertical vibration, or vertical acceleration change ratio is different between both (that on the protruded road is larger than that on the wavy road). Based on this fact, it is determined if an absolute value (|J|) of a jerk J is less than a jerk reference value JBAND or not and when it is determined as YES in a step S32, it is determined that a vehicle is traveling on the wavy road (S33). When it is determined as NO, it is determined that the vehicle is traveling on the protruded road, a control gain K'/a dead zone A' for the protruded road is set (S36), and damping characteristics applying to the protruded road can be provided, and thereby favorable ride comfortableness can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a suspension control device.

[0002]

2. Description of the Related Art As an example of a conventional suspension control device, there is a suspension control device disclosed in Japanese Patent Laid-Open No. 7-232530. This suspension control device
A variable damping coefficient shock absorber interposed between a vehicle body and an axle, an actuator for adjusting the damping coefficient of the shock absorber, an acceleration sensor for detecting a vertical acceleration of the vehicle body, and a detection of the acceleration sensor An integration processing unit that integrates data to obtain speed data; a dead zone processing unit that performs dead zone processing when the speed data is equal to or less than a predetermined value; and an adjustment data by multiplying the speed data from the dead zone processing unit by a control gain. It is roughly composed of an amplifying section for obtaining the signal and a control signal generating section for obtaining a control signal for driving the actuator based on the adjustment data. Then, the actuator is driven based on the control signal to adjust the damping coefficient of the shock absorber to generate a desired damping force, thereby improving the riding comfort and the steering stability. The suspension control device further includes an amplitude count calculating unit that calculates the number of times that the vertical acceleration data detected by the acceleration sensor or the speed data calculated by the integration processing unit goes up and down a predetermined amplitude threshold within a predetermined time (amplitude number).
A parameter adjustment unit for adjusting the control gain / dead zone (control parameter) based on the number of times of the amplitude, and suppressing vertical vibration regardless of the road surface condition (good road, parallel road, undulating road, bad road). To improve ride comfort.

[0003]

In the above-mentioned prior art, the road surface condition is determined by the number of amplitudes based on the vertical acceleration data or the speed data, and the road surface shape (for example, the shape shown in FIG. 7) is determined. until sharp road R ₂ and gentle road R ₁ form), specific (sensitive) can not be (hereinafter, the sharp shapes road called projection path, also swell to a gentle road surface shape Road.). To that extent, good suppression of vertical vibration has been hindered.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a suspension control device capable of obtaining a good ride comfort even when traveling on a bumpy road.

[0005]

According to the present invention, there is provided a shock absorber interposed between a vehicle body and an axle, the damper having an adjustable damping force, an actuator for adjusting a damping force generated by the shock absorber, An acceleration sensor for detecting the vertical acceleration of the vehicle body, a dead zone processing unit for performing dead zone processing on the detection data of the acceleration sensor, and a control signal calculation for obtaining the control signal for driving the actuator based on the dead zone processing signal processed by the dead zone processing unit Means for calculating a rate of change of acceleration by differentiating the detection data of the acceleration sensor, and a rate of change of acceleration calculated by the means for calculating rate of change of acceleration is preset. Determining means for determining whether the acceleration change rate is greater than a reference value; and determining that the acceleration change rate is greater than the reference value. Case, characterized in that a dead band adjusting means to widen adjusting the width of the dead zone.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A suspension control device according to a first embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, a spring 3 and a shock absorber 4 capable of adjusting a damping force are interposed in parallel between a vehicle body 1 (above the spring) and wheels 2 (below the spring) constituting the vehicle. Supports 1.

When the damping force on the compression side is a small value, the shock absorber 4 makes the damping force on the extension side variable between a small value and a large value, and when the damping force on the extension side is a small value,
This is a so-called expansion / contraction inversion type in which the compression-side damping force exhibits a variable damping force characteristic between a small value and a large value. The shock absorber 4 is provided with an actuator 5 for adjusting a damping force of the shock absorber 4 by operating a damping force adjusting mechanism (not shown) provided in the shock absorber 4.

On the vehicle body 1, an acceleration sensor 6 for detecting vertical acceleration (sprung acceleration) α with respect to the absolute coordinate system of the vehicle body 1 is mounted. The acceleration α detected by the acceleration sensor 6 is supplied to a controller (control means) 7. Although four shock absorbers 4 and four springs 3 are provided corresponding to the four wheels 2, only one of them is shown for convenience.

As shown in FIG. 2, a controller 7 integrates an acceleration α to obtain a vertical velocity V.
A dead band processing unit 9 for performing dead band processing when the speed V is equal to or lower than a predetermined value; and an amplifier circuit for obtaining adjustment data C by multiplying a dead band processing signal H from the dead band processing unit 9 by an adjustable control gain K. And a control signal generator (control signal calculating means) 11 for obtaining a control signal CS for driving the actuator 5 based on the adjustment data C. Further, the controller 7 differentiates the acceleration α to calculate an acceleration change rate (hereinafter, referred to as jerk) J, and a jerk J (acceleration change rate calculating means) 12.
(Determining means) 13 that determines the road surface condition based on the comparison result by comparing the dead zone A and the control gain K of the dead zone processing unit 9 based on the determination result by the determining unit 13. And a parameter adjusting unit (dead zone adjusting means) 14 for adjusting (control parameters).

The dead zone processing unit 9 receives the speed data V, and outputs a signal (in proportion to the speed data V) substantially over the entire negative (-) area (contracting side) and positive (+) area (extending side). Hereinafter, for the sake of convenience, the dead zone processing signal is output.) H is output, while the dead zone processing signal H is set to “0” in a region (dead zone) A where the absolute value of the speed data V is small. For the sake of convenience, the correspondence between the speed data V and the dead zone processing signal H is schematically shown in the block showing the dead zone processing section 9 in FIG. The control signal generator 11 outputs a control signal CS obtained based on the adjustment data C to the actuator 5 and drives the actuator 5 to send the control signal CS to the shock absorber 4, and thus the adjustment data C (speed data V, vertical direction). Is generated in accordance with the acceleration α).

The determination unit 13 determines the absolute value of the jerk J (| J
|) Is compared with the jerk reference value J _BAND and | J | is equal to or less than the jerk reference value J _BAND (that is, the change in the vertical acceleration α is small) (that is, the change in the vertical acceleration α is large).
If the following is determined (YES), the vehicle is considered to be traveling on a normal road, and if it is determined to be no (NO),
The vehicle is considered to be running on a bumpy road.

When it is determined that the vehicle is traveling on an ordinary road, the parameter adjustment unit 14 sets the control gain K / dead zone A for the ordinary road, and determines that the vehicle is traveling on a bumpy road. Then, the control gain K '/ dead zone A' for the projecting road is set. In this case, the control gain K '/ dead zone A' for the projecting road is smaller than the control gain K / dead zone A for the ordinary road, and the dead zone A 'is increased.

The operation of the suspension control device configured as described above will be described below together with the contents of the arithmetic processing of the controller 7. In FIG. 3, the controller 7
Receives the power supply from the main power supply (not shown), the control software of the controller 7 starts to be executed (step S1), and in the next step S2, an initial operation for driving the actuator 5 in step S4 described later is performed. Performs initialization (initialization) of operation values and the like. Subsequently, the control cycle t [m
s] It is determined whether or not the time has elapsed (step S3).

If NO is determined in step S3, it is determined again whether or not the control cycle t [ms] has elapsed. Steps
If YES is determined in S3, the control signal CS obtained in step S7 (previous control cycle) described later is output to the actuator 5 to drive the actuator 5 (step S4).
Subsequent to step S4, a signal is output to another member such as an LED to control each member (step S5).

Next, a detection signal from the acceleration sensor 6 is input (step S6). Subsequent to step S6, a road surface determination subroutine is executed (step S7), and a control signal CS obtained from the operation of the subroutine of step S7 is supplied to the actuator 5 to drive the actuator 5 so that a desired damping force is obtained. To control the damping force of the shock absorber 4 (step S8).

Here, the road surface determination subroutine of step S7 will be described with reference to FIG. First, the jerk J is calculated by differentiating the acceleration α (step S11). In the following step S12, the absolute value of the jerk J becomes the jerk reference value J.
It is determined whether it is equal to or less than _BAND (| J | ≦ J _BAND ?). If YES is determined in the step S12, the vehicle is regarded as traveling on a normal road (step S13), the control gain K / dead zone A for the normal road is set (step S14), and the process returns to the main routine. If NO is determined in step S12,
It is assumed that the vehicle is traveling on a bumpy road (step S15
), The control gain K '/ dead zone A' for the projecting road is set (step S16), and the process returns to the main routine.

Then, in the state where the control gain K / dead zone A for the ordinary road or the control gain K '/ dead zone A' for the protruding road is set, the control signal generator 11 is set as described above.
Outputs a control signal CS to the actuator 5 to drive the actuator 5, and sends a control signal C to the shock absorber 4.
Then, a damping force having a magnitude corresponding to the acceleration α in the vertical direction is generated.

In this case, as described above, the control gain is
The reason for setting large on a normal road and small on a protruding road (control gain K> control gain K ′) is as follows.
When the vehicle is traveling on a bumpy road, the piston speed of the shock absorber 4 is higher than when traveling on a normal road, so that even if the control gain is small, a sufficient vibration damping effect can be obtained as in the case of traveling on a normal road. On the other hand, if the control gain is increased, the damping force (damping force) increases, leading to deterioration in ride comfort, and this is to prevent such a situation from occurring.

Further, as described above, the dead zone is set small on a normal road and large on a projecting road (dead zone A <dead zone A '). As a result, frequent vertical vibrations caused by running on a bad road can be appropriately controlled as in the case of running on a normal road, so that deterioration in ride comfort can be prevented.

When traveling on a normal road or a bumpy road, the vertical vibration, and thus the rate of change of the vertical acceleration,
Both are different (the protruding road is larger than the normal road), and it is possible to determine the normal road or the protruding road based on the rate of change of the acceleration. In the present embodiment, as described above, the normal road and the protruding road are determined based on whether or not the absolute value (| J |) of the jerk J is equal to or less than the jerk reference value J _BAND . For this reason, the control gain K '/ dead zone A' for the protruding road is set when the vehicle is running on a protruding road, and the riding comfort and the steering stability can be appropriately maintained even when the vehicle is running on a protruding road.

Next, a suspension control device according to a second embodiment of the present invention will be described with reference to FIGS. This suspension control device is different from the first embodiment in that the controller 7 has an amplitude count calculating unit 20 as shown in FIG. The difference is that the road surface determination is performed based on the jerk J and the road surface determination subroutine performs the calculation of FIG. 6 instead of FIG. In the following description, members and portions equivalent to those in the first embodiment will be appropriately omitted. The number-of-amplitude calculation unit 20 calculates an amplitude threshold α for comparison with the acceleration α from the acceleration sensor 6.
_BAND , and the number of times that the value of two temporally preceding and succeeding accelerations α changes from small to large and / or large to small compared to the amplitude threshold α _BAND during 1 s (1000 ms) is determined. The signal F is output to the determination unit 13.

The operation of the thus configured suspension control device will be described below together with the contents of the arithmetic processing of the controller 7. In this case, the controller 7 executes steps S1 to S6 and S8 of the flowchart of FIG. 3 similarly to the controller 7 of the first embodiment, but replaces the road surface determination subroutine of step S7 (FIG. 4) of FIG. FIG.
The road surface determination subroutine shown in FIG.

In this road surface determination subroutine, first, a jerk J is calculated based on the acceleration α (step S21).
In steps S22 to S27 following step S21, the number of times of frequency (frequency) of the acceleration signal α during the latest 1 second (1000 ms) is calculated. That is, the absolute value of the acceleration signal α (|
alpha |) Set the amplitude threshold alpha _BAND to be compared with the absolute value of the previous acceleration signal α _F (| α _F |) is smaller than the amplitude threshold alpha _BAND (determined NO in step S22), and and the current acceleration signal alpha
_When the absolute value of _P (| α _P |) is larger than the amplitude threshold α _BAND (determined as YES in step S23), the counter is set to “1”.
Increment (step S24).

Similarly, the absolute value of the front acceleration signal α _F (| α _F
Is greater than or equal to the amplitude threshold α _BAND (determined as YES in step S22) and the absolute value (| α _P |) of the current acceleration signal α _P is smaller than the amplitude threshold α _BAND (determined as YES in step S25), The counter is incremented by "1" (step S26).

After the process in step S24, after the process in step S26, when the determination in step S23 is NO, or when the determination in step S25 is NO,
Two acceleration signals chronologically successive α (α _F, α _P) absolute value of seek times (the amplitude of times) F ₁₀₀₀ which changes the small from large Oyobi large from the small than the amplitude threshold alpha _BAND (step
S27). Note that, here, both the number of times of change from small to large and large to small are obtained, but any one of numbers of change from small to large or large to small may be obtained.

[0026] determines whether the amplitude number F ₁₀₀₀ Following step S27 is in the low-side count reference value F _L to the high side count reference value F _H is set in advance (step S28). If YES is determined in the step S28, it is determined that the vehicle is traveling on a normal road (step S29), and the control gain K / dead zone A for the normal road is set (step S30).
), Prior to the acceleration signal alpha _F to the current acceleration signal alpha _P (step S31), and control returns to the main routine.

If NO is determined in the step S28, it is determined whether or not the absolute value (| J |) of the jerk J is equal to or less than the jerk reference value J _BAND (step S32). If "YES" is determined in the step S32, it is determined that the vehicle is traveling on the undulating road (step S33), and the control gain K "/ dead zone A" for the undulating road.
Is set (step S34), and the process proceeds to step S31.
If NO is determined in step S28, it is determined that the vehicle is traveling on a bumpy road (step S35), and the control gain K '/ dead zone A' for the bumpy road is set (step S36), and the flow proceeds to step S31. In this case, regarding the control gain / dead zone for the normal road, the undulating road, and the projecting road, in this order, the control gain is small (K> K ″> K ′) and the dead zone is large (A> A ″> A ′). Have been.

Then, with the control gain / dead zone set for the normal road, the undulating road, or the projecting road, the control signal generator 11 outputs the control signal CS to the actuator 5 as described above. The actuator 5 is driven to cause the shock absorber 4 to generate a damping force having a magnitude corresponding to the control signal CS and, consequently, the vertical acceleration α.

In this case, the control gain is
On the other hand, while the piston speed of the shock absorber 4 is increased in this order, while the piston speed of the shock absorber 4 is increased in the order of (K) for the normal road (K), for the undulating road (K ″), and for the projecting road (K ′), Road, it is possible to set the gain to obtain a sufficient damping effect according to the bumpy road,
As a result, it is possible to maintain a sufficient vibration damping effect and good riding comfort regardless of whether the road is a normal road, a undulating road, or a bumpy road.

Further, as described above, the dead zone is increased in the order of the normal road, the undulating road, and the protruding road. Therefore, as the change rate of the vertical vibration increases, the attenuation becomes larger than required. Excessive control due to the generation of force is suppressed, and frequent vertical vibrations caused by running on a bumpy road or undulating road can be appropriately controlled in the same manner as when driving on a normal road, so that deterioration in ride comfort can be prevented.

When traveling on a undulating road or a bumpy road, the vertical vibration, and hence the rate of change of the vertical acceleration,
The two are different (the protruding road is larger than the proving road), and it is possible to determine the proving road or the protruding road based on the rate of change in acceleration. In the present embodiment, as described above, the undulating road and the protruding road are determined based on whether or not the absolute value (| J |) of the jerk J is equal to or less than the jerk reference value J _BAND . For this reason, the control gain K ″ / dead zone A ″ for the undulating road is set during the undulating road, and the riding comfort and the steering stability can be appropriately maintained even during the undulating road.

The applicant of the present invention is directed to the second embodiment (in which the undulating road and the projecting road are discriminated by using the jerk J) and the conventional technology that does not use the jerk J. We investigated whether the road could be identified. The contents of this investigation will be described with reference to FIG. In this investigation, as shown in FIG. 7, the vehicle is divided into a normal road (flat road) R ₀ , a swell road (gently shaped road surface) R ₁ , and a projecting road (sharp road surface) R _2.
As an example, the vehicle travels in the order of swelling road R ₁ , projection road R
₂ is the amplitude threshold α
_Shall exceed _BAND .

At this time, the waveform of the acceleration α in the vertical direction on the undulating road R ₁ and the protruding road R ₂ is steeper on the protruding road R ₂ . Then, along with this, the undulating road R ₁ , the projection road R
Jerk J in _2, the amplitude value is steep towards the projection path R ₂ is increased, for example, undulating road jerk in R ₁ J (| J |) whereas fall within jerk reference value J _BAND,
Jerk J in projection path R ₂ (| J |) will exceed jerk reference value J _BAND.

In the prior art that does not use the jerk J, the vertical acceleration α exceeds the amplitude threshold α _BAND , as shown in the column of “road surface determination result (no jerk)” in FIG. corresponding portions will be determined to be undulating road, which leads to erroneous determination result in the undulating road even when the projection path R _2.

On the other hand, in the second embodiment,
Jerk J (| J |) by is falls within jerk reference value J _BAND, as shown in the column "road determination result (Yes jerk)" in FIG. 7, undulating road the corresponding portion (undulating road R ₁ ), And since the jerk J (| J |) exceeds the jerk reference value J _BAND , it is possible to determine that the corresponding portion is a protruding road (protruding road R ₂ ), thereby improving the determination accuracy. be able to.

[0036]

Since the present invention is a suspension control device configured as described above, when traveling on a normal road, a undulating road, or a bumpy road, the vertical vibration, and consequently, the rate of change of the vertical acceleration, Both are different (the protruding road is larger than the normal road and the undulating road), and it is possible to determine the normal road (undulating road) and the protruding road based on the rate of change in acceleration. By discriminating between a normal road (undulating road) and a protruding road based on the rate of change in acceleration, it is possible to adjust control parameters including a dead zone of a size corresponding to the normal road, the undulating road, and the protruding road. As a result, it is possible to appropriately improve the riding comfort and maintain the steering stability even when traveling on a normal road, a undulating road, or a bumpy road.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing the controller of FIG. 1;

FIG. 3 is a flowchart showing control contents of a controller of FIG. 2;

FIG. 4 is a flowchart showing a road surface determination subroutine of FIG. 3;

FIG. 5 is a block diagram showing a controller used in a second embodiment of the present invention.

FIG. 6 is a flowchart illustrating a road surface determination subroutine of the controller of FIG. 5;

FIG. 7 is a signal waveform diagram for explaining an operation of the second exemplary embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 4 Shock absorber 5 Actuator 6 Acceleration sensor 7 Controller 12 Differentiator circuit (Acceleration change rate calculating means) 14 Parameter adjusting section (Dead zone adjusting means)

Claims (1)

[Claims] 1. A shock absorber interposed between a vehicle body of a vehicle and an axle and capable of adjusting a damping force, an actuator for adjusting a damping force generated by the shock absorber, and an acceleration for detecting a vertical acceleration of the vehicle body A suspension control unit comprising: a sensor; a dead zone processing unit that performs dead zone processing on data detected by the acceleration sensor; and a control signal calculation unit that obtains a control signal for driving the actuator based on the dead zone processing signal processed by the dead zone processing unit. In the device, an acceleration change rate calculating means for differentiating the detection data of the acceleration sensor to calculate an acceleration change rate, and whether or not the acceleration change rate calculated by the acceleration change rate calculating means is larger than a preset reference value Determining means for determining the width of the dead zone when the determining means determines that the acceleration change rate is greater than a reference value. Suspension control device characterized by comprising a dead band adjusting means to widen adjusted.