JP2022125573A - suspension controller - Google Patents

Abstract

[Problem] To provide a suspension control device that can correctly detect vertical behavior even during cornering and acceleration/deceleration. [Solution] A controller 12 controls an actuator 7 of a shock absorber 6 interposed between a vehicle body 1 and wheels 2 of a vehicle. A lateral acceleration sensor 10 detects the lateral acceleration of the vehicle. A longitudinal acceleration sensor 11 detects the longitudinal acceleration of the vehicle. The controller 12 has a lateral G correction unit 22 that determines a roll angle using the lateral acceleration detected by the lateral acceleration sensor 10, and a longitudinal G correction unit 23 that determines a pitch angle using the longitudinal acceleration detected by the longitudinal acceleration sensor. [Selected Figure] Figure 3

Description

TECHNICAL FIELD The present disclosure relates to a suspension control device that is mounted on a vehicle such as a four-wheeled vehicle and that is preferably used to damp vibrations of the vehicle.

In general, a vehicle such as an automobile is provided with a damping force adjustable shock absorber between the vehicle body and each axle, and a suspension control device configured to adjust the damping force characteristics of this shock absorber is mounted (for example, , see Patent Document 1). In this type of conventional suspension control system, the vertical vibration of the vehicle body is detected as sprung speed or sprung acceleration, and the shock absorber is controlled so as to generate a damping force corresponding to the detected speed or the like. rice field.

JP 2014-69759 A

By the way, in the suspension control device disclosed in Patent Document 1, the vertical acceleration sensor signal is integrated, sprung speed, unsprung speed, relative speed, etc. are calculated, and skyhook control and bilinear control are performed using the calculated values. Optimum control (BLQ control) is performed. Generally, this integration process is combined with a high-pass filter (HPF) to remove the effects of banks and gradients. However, when turning or decelerating, the detection axis of the acceleration sensor is tilted due to roll and pitch. Due to the inclination of the detection axis, the generated lateral and longitudinal accelerations are detected as vertical acceleration components (turning acceleration/deceleration effect vertical acceleration). During gentle turning and acceleration/deceleration, the HPF process reduces the estimation error due to the vertical acceleration due to the turning acceleration/deceleration. However, with large turning acceleration/deceleration and high-frequency input, the HPF processing cannot remove the vertical acceleration affected by turning acceleration/deceleration, resulting in errors in estimating sprung speed, relative speed, etc., resulting in reduced ride comfort. Resulting in. On the other hand, if you try to reduce the effect of turning acceleration/deceleration by changing the cut-off frequency of the HPF processing to a higher frequency, the frequency characteristics of the sprung speed in the control target area will deteriorate, and the performance will decrease even when driving straight. There's a problem.

SUMMARY OF THE INVENTION An object of an embodiment of the present invention is to provide a suspension control device capable of correctly detecting vertical behavior even during turning, acceleration and deceleration.

An embodiment of the present invention is a suspension control device for controlling an actuator interposed between a vehicle body and wheels of a vehicle, wherein a lateral acceleration detection value obtained by lateral acceleration detection means is used to detect a roll angle. and a pitch angle calculation unit for obtaining the pitch angle using the longitudinal acceleration detection value by the longitudinal acceleration detecting means for detecting the longitudinal acceleration.

According to one embodiment of the present invention, vertical behavior can be detected correctly even during turning and during acceleration/deceleration.

1 is a diagram schematically showing a suspension control device according to a first embodiment; FIG. 2 is a block diagram showing a controller in FIG. 1; FIG. 3 is a block diagram showing a lateral G corrector, a longitudinal G corrector, and a vertical acceleration corrector in FIG. 2; FIG. FIG. 3 is an explanatory diagram showing a damping force limiter in FIG. 2; FIG. 3 is an explanatory diagram showing a maximum damping coefficient map in FIG. 2; FIG. 3 is an explanatory diagram showing an attenuation coefficient map in FIG. 2; FIG. 4 is an explanatory diagram showing lateral acceleration, roll angle, and lateral acceleration vertical component; FIG. 4 is an explanatory diagram showing longitudinal acceleration, pitch angle, and vertical component of longitudinal acceleration; FIG. 4 is a characteristic diagram showing temporal changes in lateral acceleration, roll angle, vertical acceleration sensor value, and corrected vertical acceleration; FIG. 5 is a diagram schematically showing a suspension control device according to a second embodiment; FIG. 8 is a block diagram showing a lateral G corrector, a longitudinal G corrector, and a vertical acceleration corrector according to the second embodiment; FIG. FIG. 10 is a block diagram showing a roll angle calculator in FIG. 9; FIG. FIG. 10 is a block diagram showing a pitch angle calculator in FIG. 9; FIG. FIG. 4 is a block diagram showing a suspension displacement roll/pitch angle calculator; FIG. 4 is a block diagram showing a tire displacement roll/pitch angle calculator; 3 is a block diagram showing a tire displacement roll angle calculator and a tire displacement pitch angle calculator; FIG.

Hereinafter, a case where the suspension control device according to the embodiment is applied to, for example, a four-wheeled vehicle will be described in detail with reference to the accompanying drawings.

First, FIGS. 1 to 9 show a first embodiment of the invention. The vehicle body 1 constitutes the body of the vehicle. For example, left and right front wheels and left and right rear wheels (hereinafter collectively referred to as wheels 2 ) are provided on the lower side of the vehicle body 1 , and the wheels 2 include tires 3 . At this time, the tire 3 acts as a spring that absorbs fine irregularities on the road surface.

The suspension device 4 is interposed between the vehicle body 1 and the wheels 2 . The suspension device 4 includes a suspension spring 5 (hereinafter referred to as spring 5) and a damping force adjustable shock absorber (hereinafter referred to as shock absorber 6) provided between the vehicle body 1 and the wheel 2 in parallel with the spring 5. ) and In addition, in FIG. 1, the case where one set of suspension apparatuses 4 is provided between the vehicle body 1 and the wheel 2 is illustrated. However, the suspension device 4 is provided, for example, in total four sets independently between the four wheels 2 and the vehicle body 1, of which only one set is schematically shown in FIG. .

Here, the damper 6 of the suspension device 4 is a force generating mechanism, and is configured using a damping force adjustable hydraulic damper. The shock absorber 6 includes a damping force adjusting valve or the like in order to continuously adjust the characteristics of the generated damping force (damping force characteristics) from hard characteristics (hard characteristics) to soft characteristics (soft characteristics). An actuator 7 is attached. Note that the damping force adjustment valve may be capable of adjusting the damping force characteristics in two stages or in a plurality of stages instead of continuously. Also, the buffer 6 may be of the pressure control type or the flow rate control type.

A sprung acceleration sensor 8 is provided on the vehicle body 1 . The sprung acceleration sensor 8 constitutes vertical acceleration detection means for detecting vertical acceleration. Specifically, the sprung acceleration sensor 8 is attached to the vehicle body 1 at a position near the shock absorber 6, for example. The sprung acceleration sensor 8 detects vertical acceleration, which is vibration acceleration in the vertical direction, on the vehicle body 1 side, which is the so-called sprung side. The sprung acceleration sensor 8 outputs the sprung vertical acceleration sensor value to the controller 12 .

The unsprung acceleration sensor 9 is provided on the wheel 2 side of the vehicle. The unsprung acceleration sensor 9 detects vertical acceleration, which is vibration acceleration in the vertical direction, on the wheel 2 side, which is the so-called unsprung side. The unsprung acceleration sensor 9 outputs an unsprung vertical acceleration sensor value to the controller 12 .

At this time, the sprung acceleration sensor 8 and the unsprung acceleration sensor 9 constitute vertical motion detection means for detecting the state of the vertical motion of the vehicle. The vertical motion detecting means is not limited to the sprung acceleration sensor 8 and the unsprung acceleration sensor 9 provided near the shock absorber 6. For example, the sprung acceleration sensor 8 alone or the vehicle height sensor may be used. may be detected by providing one sprung acceleration sensor 8 on the vehicle body and estimating the vertical motion of each wheel based on other sensor information such as a wheel speed sensor.

Lateral acceleration sensor 10 and longitudinal acceleration sensor 11 are both provided on vehicle body 1 . The lateral acceleration sensor 10 detects lateral acceleration, which is lateral acceleration on the vehicle body 1 side. The lateral acceleration sensor 10 outputs a lateral acceleration sensor value as a lateral acceleration detection value to the controller 12 . The longitudinal acceleration sensor 11 detects longitudinal acceleration, which is longitudinal acceleration on the vehicle body 1 side. The longitudinal acceleration sensor 11 outputs a longitudinal acceleration sensor value as a longitudinal acceleration detection value to the controller 12 .

The controller 12 comprises, for example, a microcomputer or the like, and constitutes control means for controlling the damping force generated by the shock absorber 6 based on the detection results of the acceleration sensors 8 to 11 and the like. The input side of the controller 12 is connected to the acceleration sensors 8 to 11 and the like. The output side of the controller 12 is connected to the actuator 7 of the shock absorber 6 and the like. Further, the controller 12 has a storage section 12A composed of ROM, RAM and the like.

The storage unit 12A of the controller 12 stores a maximum damping coefficient map 19 for outputting a maximum damping coefficient Cmax based on the relative speed V2 shown in FIG. 5, a correction damping coefficient Ca shown in FIG. and a damping coefficient map 21 showing the relationship between .

As shown in FIG. 2, the controller 12 includes integrators 13 and 14, a subtractor 15, a target damping force calculator 16, a damping force limiter 17, a damping coefficient calculator 18, a maximum damping coefficient map 19, and a minimum value selector. 20, with a damping coefficient map 21;

In addition to this, the controller 12 includes a lateral acceleration component corrected vertical acceleration calculator 22 (hereinafter referred to as the lateral G corrector 22), a longitudinal acceleration component corrected vertical acceleration calculator 23 (hereinafter referred to as the longitudinal G corrector 23), a vertical acceleration A correction unit 24 is provided (see FIGS. 2 and 3).

The integrator 13 of the controller 12 receives the corrected vertical acceleration obtained by correcting the detection result (vertical acceleration sensor value) from the sprung acceleration sensor 8 by the lateral G correction unit 22, the longitudinal G correction unit 23, and the like. The integrator 13 of the controller 12 calculates the sprung velocity V1, which is the velocity of the vehicle body 1 in the vertical direction, by integrating the corrected vertical acceleration. For this reason, the sprung acceleration sensor 8 and the integrator 13 constitute vehicle-side vertical velocity detection means, and the integrator 13 outputs the sprung velocity V1, which is the vehicle-side vertical velocity.

On the other hand, the subtractor 15 subtracts the unsprung vertical acceleration detected by the unsprung acceleration sensor 9 from the sprung corrected vertical acceleration to calculate the difference between the sprung acceleration and the unsprung acceleration. This difference value then corresponds to the relative acceleration between the vehicle body 1 and the wheels 2 . Then, the integrator 14 integrates the relative acceleration output from the subtractor 15, and calculates the vertical relative velocity between the vehicle body 1 and the wheels 2 as the relative velocity between the sprung and unsprung parts of the shock absorber 6. Calculate the velocity V2. Therefore, the sprung acceleration sensor 8, the unsprung acceleration sensor 9, the subtractor 15 and the integrator 14 constitute relative velocity detection means, and the integrator 14 outputs the relative velocity V2.

A target damping force calculator 16 outputs a target damping force DF to be generated in the shock absorber 6 based on the sprung speed V1. This target damping force DF is obtained from, for example, Skyhook control theory. Specifically, as shown in Equation 1 below, the target damping force calculator 16 multiplies the skyhook damping coefficient Csky obtained from the skyhook control theory by the sprung velocity V1 to obtain the target damping force DF. Calculate Note that the target damping force calculator 16 may calculate the target damping force based on, for example, bilinear optimum control (BLQ control) instead of Skyhook control theory.

The damping force limiter 17 independently limits the maximum value of the target damping force DF with a positive value and a negative value. As shown in FIG. 4, when the sprung speed V1 is on the positive side and the target damping force DF is smaller than a predetermined positive threshold DFt (DF<DFt), the damping force limiter 17 When a limited target damping force DF _lim having the same value as the target damping force DF is output and the target damping force DF is greater than the threshold value DFt (DF≧DFt), the damping force limiter 17 outputs the same value as the threshold value DFt. Outputs the limit target damping force DF _lim .

Similarly, when the sprung velocity V1 is on the negative side and the target damping force DF is greater than a predetermined negative side threshold value (-DFt) (DF>-DFt), the damping force limiter 17 When a limited target damping force DF _lim having the same value as the target damping force DF is output and the target damping force DF is smaller than the threshold value (-DFt) (DF≤-DFt), the damping force limiter 17 outputs the threshold value. Output the limit target damping force DF _lim of the same value as the value (-DFt).

That is, when the absolute value of the target damping force DF is smaller than the absolute value of the threshold value DFt (|DF|<|DFt|), the damping force limiter 17 sets the limit target damping force equal to the target damping force DF. DF _lim is output, and when the absolute value of the target damping force DF exceeds the threshold DFt (|DF|≧|DFt|), the damping force limiter 17 outputs a value equal to the threshold (±DFt). Outputs the limit target damping force DF _lim . At this time, the threshold DFt is set to a value smaller than the damping force that can be generated by the damper 6 . Therefore, the damping force limiter 17 sets the limited target damping force DF _lim smaller than the damping force that can be generated by the shock absorber 6 .

The threshold value DFt may be set to the same value on the positive side and the negative side of the relative speed V2. You can set it to different values.

A damping coefficient calculator 18 calculates a target damping coefficient C based on the limited target damping force DF _lim and the relative speed V2. Specifically, the damping coefficient calculator 18 calculates the target damping coefficient C by dividing the relative velocity V2 from the limited target damping force DF _lim , as shown in the following equation (2).

In this case, the target damping force calculator 16, the damping force limiter 17, and the damping coefficient calculator 18 constitute target damping coefficient calculation means for calculating the target damping coefficient C based on the detection results of the acceleration sensors 8 and 9. .

The maximum damping coefficient map 19 has a characteristic line 19A showing the relationship between the relative speed V2 and the maximum damping coefficient Cmax, and outputs the maximum damping coefficient Cmax based on the relative speed V2. At this time, the maximum damping coefficient Cmax is set to a value within a range that does not exceed the maximum damping coefficient that can be generated by the buffer 6 . As shown in FIG. 5, the maximum damping coefficient Cmax is set to a small value when the relative speed V2 is lower than the predetermined threshold value Vt, and is set to a large value when the relative speed V2 is higher than the threshold value Vt. set.

Specifically, when the relative speed V2 is lower than the threshold value Vt (-Vt<V2<Vt), the maximum damping coefficient Cmax is set to the small low speed set value C1. On the other hand, when the elongation side (positive side) relative speed V2 is higher than the threshold value Vt (V2>Vt), the maximum damping coefficient Cmax is set to the high speed setting value C2 which is larger than the low speed setting value C1. set. Similarly, when the contraction side (negative side) relative velocity V2 is higher than the threshold value Vt (V2<-Vt), the maximum damping coefficient Cmax is set to the high speed set value larger than the low speed set value C1. Set to C3.

When the relative speed V2 is close to the threshold value Vt, the maximum damping coefficient Cmax may be set to a value between the low speed setting value C1 and the high speed setting value C2. Similarly, when the relative speed V2 is close to the threshold value (-Vt), the maximum damping coefficient Cmax may be set between the low speed setting value C1 and the high speed setting value C3.

The high speed setting values C2 and C3 are appropriately set in consideration of the structure, specifications, damping force characteristics, etc. of the shock absorber 6. FIG. Further, although the low speed set value C1 and the high speed set values C2 and C3 are all constant values, they may be changed according to the relative speed V2.

The threshold value Vt is obtained experimentally in consideration of the occurrence of jerk, for example, and is appropriately set according to the structure of the shock absorber 6, damping force characteristics, and the like. Also, the threshold value Vt may be set to the same value on the positive side and the negative side of the relative velocity V2, or may be set to different values on the positive side and the negative side of the relative velocity V2.

The minimum value selector 20 compares the target damping coefficient C output from the damping coefficient calculator 18 and the maximum damping coefficient Cmax output from the maximum damping coefficient map 19, and selects the smaller one of these coefficients C and Cmax. is selected and output as the corrected attenuation coefficient Ca. Therefore, the minimum value selector 20 and the maximum damping coefficient map 19 constitute correction means for calculating a corrected damping coefficient Ca by lowering the upper limit of the target damping coefficient C when the relative speed V2 is low.

The damping coefficient map 21 constitutes control signal output means and outputs a command current value I as a control signal corresponding to the corrected damping coefficient Ca. As shown in FIG. 6, the damping coefficient map 21 variably sets the relationship between the corrected damping coefficient Ca and the command current value I according to the relative speed V2, and is created based on test data by the inventors. is. The damping coefficient map 21 sets the command current value I for adjusting the damping force characteristic of the buffer 6 based on the corrected damping coefficient Ca from the minimum value selector 20 and the relative velocity V2 from the integrator 14. Then, this command current value I is output to the actuator 7 of the damper 6 .

The damping coefficient map 21 also outputs a control signal (command current value I) for controlling the damper 6 so that the damping force adjustable damper conforms to the Skyhook theory. This attenuation coefficient map 21 has a hard side characteristic line 21A indicated by a solid line in FIG. 6 and a soft side characteristic line 21B indicated by a broken line in FIG. At this time, the hardware-side characteristic line 21A is arranged in a range in which the corrected attenuation coefficient Ca is larger than the software-side characteristic line 21B.

Then, when the relative speed V2 and the corrected damping coefficient Ca are inputted, the intersection of the corrected damping coefficient Ca and the relative speed V2 in the damping coefficient map 21 is obtained. When this intersection is located in a range where the correction damping coefficient Ca is larger than the hard side characteristic line 21A, the command current value I is increased to set the damping force characteristic to a hard characteristic. On the other hand, when the intersection point is located in a range where the correction damping coefficient Ca is smaller than the characteristic line 21B on the soft side, the command current value I is decreased to set the damping force characteristic to a soft characteristic. Further, when the intersection point is located in the range between the characteristic line 21A on the hard side and the characteristic line 21B on the soft side, the command current value I is adjusted according to the correction damping coefficient Ca, and the damping force characteristics of the hard and the soft are adjusted. Set to medium characteristics.

As described above, the damping force generated by the shock absorber 6 is adjusted continuously between hard and soft according to the command current value I supplied to the actuator 7, or variably adjusted in a plurality of stages.

Next, the configuration of a correction processing portion for correcting the detection result (vertical acceleration sensor value) of the sprung acceleration sensor 8 by the lateral G correction section 22, the longitudinal G correction section 23, etc. will be described with reference to FIG.

The lateral G correction section 22 has a roll angle calculation section. Here, the lateral acceleration vertical component can be obtained by the following equation (3).

When the roll angle is a sufficiently small value, an approximation of a sine function (sin(φ)≈φ) holds. Therefore, sin(|roll angle [rad]|)≈|roll angle [rad]|. As a result, the vertical component of lateral acceleration can be expressed by the following equation (4).

Therefore, the lateral G correction unit 22 calculates the lateral acceleration vertical component based on the formula (4). At this time, the lateral G correction unit 22 includes a squaring unit 22A, a conversion coefficient multiplier 22B, and a gravitational acceleration divider 22C. The square calculator 22A calculates the square of the lateral acceleration. The transform coefficient multiplier 22B multiplies the output value (square value of the lateral acceleration) from the squaring unit 22A by the coefficient KAy2Roll. At this time, the coefficient KAy2Roll is a value obtained by multiplying the lateral acceleration roll angle conversion coefficient by (π/180). The gravitational acceleration divider 22C multiplies the output value from the conversion coefficient multiplier 22B by (-1) and divides the gravitational acceleration g. The roll angle calculator is composed of a part that multiplies the lateral acceleration by the coefficient KAy2Roll and divides the gravitational acceleration g.

The longitudinal G correction section 23 has a pitch angle calculation section. Here, the longitudinal acceleration vertical component can be obtained by the following equation (5).

When the pitch angle is a sufficiently small value, an approximation of a sine function (sin(θ)≈θ) holds. Therefore, sin(|pitch angle [rad]|)≈|pitch angle [rad]|. As a result, the longitudinal acceleration vertical component can be expressed by the following equation (6).

Therefore, the longitudinal G correction unit 23 calculates the vertical component of the lateral acceleration based on the equation (6). At this time, the front/rear G correction unit 23 includes a squaring unit 23A, a conversion coefficient multiplier 23B, and a gravitational acceleration divider 23C. The square calculator 23A calculates the square of the longitudinal acceleration. The conversion coefficient multiplier 23B multiplies the output value (the square value of the longitudinal acceleration) from the square operator 23A by the coefficient KAx2Pitch. At this time, the coefficient KAx2Pitch is a value obtained by multiplying the longitudinal acceleration pitch angle conversion coefficient by (π/180). The gravitational acceleration divider 23C multiplies the output value from the conversion coefficient multiplier 23B by (-1) and divides the gravitational acceleration g. The pitch angle calculator is composed of a part that multiplies the lateral acceleration by the coefficient KAx2Pitch and divides the gravitational acceleration g.

The vertical acceleration correction unit 24 converts the vertical acceleration detection value (vertical acceleration sensor value) from the sprung acceleration sensor 8, the roll angle obtained by the lateral G correction unit 22, and the pitch angle obtained by the longitudinal G correction unit 23. is used to correct the vertical acceleration detection value. The vertical acceleration corrector 24 includes an adder 24A and a subtractor 24B. Note that the vertical acceleration correction section 24 may be configured by a single calculator having both the addition function of the adder 24A and the subtraction function of the subtractor 24B.

The adder 24A adds the lateral acceleration vertical component and the longitudinal acceleration vertical component. The subtractor 24B subtracts the sum of the vertical component of the lateral acceleration and the vertical component of the longitudinal acceleration from the vertical acceleration detected by the sprung acceleration sensor 8 . Thereby, the subtractor 24B outputs a corrected vertical acceleration obtained by correcting the vertical acceleration detected by the sprung acceleration sensor 8 according to the lateral acceleration and the longitudinal acceleration.

The vehicle suspension control system according to the first embodiment has the configuration described above. Next, the process of variably controlling the damping force characteristic of the shock absorber 6 using the controller 12 will be described.

The controller 12 receives the detection result (vertical acceleration sensor value) of the vertical vibration acceleration of the sprung (vehicle 1) side from the sprung acceleration sensor 8 while the vehicle is running, and A detection result (vertical acceleration sensor value) of vertical vibration acceleration on the lower (wheel 2) side is input.

At this time, the controller 12 performs ride comfort control processing based on the obtained information, and calculates the target damping coefficient C and the relative speed V2. The maximum damping coefficient map 19 of the controller 12 outputs the maximum damping coefficient Cmax corresponding to the relative velocity V2. The minimum value selector 20 of the controller 12 selects the smaller value between the target damping coefficient C and the maximum damping coefficient Cmax and outputs it as the corrected damping coefficient Ca. The damping coefficient map 21 calculates the command current value I according to the corrected damping coefficient Ca and the relative speed V2. The command current value I is input to the actuator 7 of the damper 6 to control the driving of the actuator 7 . Thereby, the damping force characteristic of the shock absorber 6 becomes variable between a hard characteristic (hard characteristic) and a soft characteristic (soft characteristic) and is controlled continuously.

In the first embodiment, the target damping coefficient C is calculated based on the target damping force DF and the relative speed V2, and the target damping coefficient C is corrected according to the relative speed V2 to calculate the corrected damping coefficient Ca. The corrected damping coefficient Ca lowers the upper limit of the target damping coefficient C in a region where the relative speed V2 is low. A command current value I is calculated corresponding to this corrected attenuation coefficient Ca.

As a result, the command current value I rises smoothly in the first embodiment, compared to the case where the shock absorber 6 is controlled based on the target damping force DF without correction based on the relative speed V2. Therefore, it is possible to suppress a sudden change in the damping force, so that jerk can be reduced.

By the way, the detection axis of the sprung acceleration sensor 8 is tilted due to roll and pitch during turning and acceleration/deceleration. Due to the inclination of the detection axis, lateral acceleration and longitudinal acceleration may be detected as vertical acceleration components, degrading vibration damping performance.

For example, as shown in FIG. 7, when the vehicle turns, lateral acceleration acts on the vehicle body 1 according to the turning. The roll angle of the vehicle body 1 changes according to this lateral acceleration. Therefore, the sensor value of the vertical acceleration sensor (sprung acceleration sensor 8) is superimposed with the lateral acceleration component according to the roll angle, and an error occurs in the vertical acceleration (see FIG. 9). Similarly, when the vehicle accelerates or decelerates, longitudinal acceleration corresponding to acceleration or deceleration acts on the vehicle body 1 (see FIG. 8). Therefore, the pitch angle of the vehicle body 1 changes according to this longitudinal acceleration, and an error occurs in the vertical acceleration.

On the other hand, the suspension control system according to the first embodiment utilizes the fact that the lateral acceleration is proportional to the roll angle and the longitudinal acceleration is proportional to the pitch angle. Calculate the error detected as a component. The suspension control system according to the first embodiment calculates a corrected vertical acceleration by removing this error from the sensor value of the vertical acceleration sensor (sprung acceleration sensor 8) (see FIG. 9). As a result, in the first embodiment, it is possible to improve the accuracy of estimating the sprung velocity V1 and the relative velocity V2 during turning and acceleration/deceleration. As a result, in the first embodiment, the correct vertical behavior can be detected even during turning or acceleration/deceleration, so that damping performance can be improved.

Thus, the suspension control system according to the first embodiment includes a lateral G correction section 22 (roll angle calculation section) that calculates a roll angle using a lateral acceleration detection value from the lateral acceleration sensor 10 that detects lateral acceleration, and a longitudinal acceleration. and a longitudinal G corrector 23 (pitch angle calculator) that obtains the pitch angle using the longitudinal acceleration detected by the longitudinal acceleration sensor 11 . Therefore, in the first embodiment, even when turning or accelerating or decelerating, it is possible to suppress the influence of lateral acceleration and longitudinal acceleration and detect correct vertical behavior. As a result, the suspension device 4 can be controlled based on correct vertical behavior, and vibration damping performance can be improved.

The suspension control device according to the first embodiment uses a vertical acceleration detection value, a roll angle, and a pitch angle by a sprung acceleration sensor 8 (vertical acceleration detection means) that is attached to the vehicle body 1 and detects vertical acceleration. and a vertical acceleration correction unit 24 for correcting the vertical acceleration detection value. Therefore, in the first embodiment, even if an error occurs in the vertical acceleration detection value due to lateral acceleration or longitudinal acceleration, such an error can be reduced by the vertical acceleration corrector 24, so that the correct vertical behavior can be detected. can do.

Next, FIGS. 10 to 16 show a second embodiment of the present invention, which is characterized by estimating roll angle and pitch angle and using these values, lateral acceleration, and longitudinal acceleration. The object is to calculate a corrected vertical acceleration. In addition, in 2nd Embodiment, the same code|symbol shall be attached|subjected to the component same as 1st Embodiment, and the description shall be abbreviate|omitted.

As shown in FIG. 10, four-wheel vehicle height sensors 32FL, 32FR, 32RL, and 32RR are connected to the controller 31 according to the second embodiment. The vehicle height sensor 32FL outputs the vehicle height of the left front wheel. The vehicle height sensor 32FR outputs the vehicle height of the right front wheel. The vehicle height sensor 32RL outputs the vehicle height of the left rear wheel. The vehicle height sensor 32RR outputs the vehicle height of the right rear wheel.

The controller 31 is composed of, for example, a microcomputer or the like, and constitutes control means for controlling the damping force generated by the shock absorber 6 based on the detection results of the acceleration sensors 8 to 11 and the vehicle height sensors 32FL, 32FR, 32RL, 32RR. ing. The controller 31 has a storage unit 31A made up of ROM, RAM and the like.

The controller 31 is configured similarly to the controller 12 according to the first embodiment. Therefore, the controller 31 includes integrators 13 and 14, a subtractor 15, a target damping force calculator 16, a damping force limiter 17, a damping coefficient calculator 18, a maximum damping coefficient map 19, a minimum value selector 20, a damping coefficient A map 21 is provided.

In addition, the controller 31 includes a lateral acceleration component corrected vertical acceleration calculator 33 (hereinafter referred to as the lateral G corrector 33), a longitudinal acceleration component corrected vertical acceleration calculator 39 (hereinafter referred to as the longitudinal G corrector 39), a vertical acceleration A correction unit 24 is provided (see FIG. 11). The vertical acceleration correction unit 24 calculates the vertical acceleration detection value (vertical acceleration sensor value) by the sprung acceleration sensor 8, the roll angle obtained by the roll angle calculation unit 34 of the lateral G correction unit 33, and the pitch of the longitudinal G correction unit 39. The vertical acceleration detection value is corrected using the pitch angle obtained by the angle calculator 40 . Specifically, the vertical acceleration correction unit 24 subtracts the sum of the vertical component of the lateral acceleration and the vertical component of the longitudinal acceleration from the vertical acceleration detected by the sprung acceleration sensor 8 . Thereby, the vertical acceleration correction unit 24 outputs a corrected vertical acceleration obtained by correcting the vertical acceleration detected by the sprung acceleration sensor 8 according to the lateral acceleration and the longitudinal acceleration.

The lateral G correction unit 33 calculates the lateral acceleration vertical component based on the equation (3). As shown in FIG. 11, the lateral G correction section 33 includes a roll angle calculation section 34, an absolute value calculation section 35, a sine calculation section 36, a multiplier 37, and a sign inversion calculation section . The roll angle calculator 34 calculates the roll angle of the vehicle body 1 based on the vehicle height, lateral acceleration, and longitudinal acceleration of the four wheels. The absolute value calculator 35 calculates the absolute value of the roll angle. A sine calculator 36 obtains the value of the sine function for the absolute value of the roll angle. A multiplier 37 multiplies the value output from the sin calculator 36 by the lateral acceleration sensor value. The sign inversion calculator 38 inverts the sign of the value output from the multiplier 37 .

As shown in FIG. 12 , the roll angle calculator 34 includes an adder 34A that adds the roll angle based on the displacement of the suspension device 4 and the roll angle based on the displacement of the tires 3 . The roll angle calculator 34 adds the roll angles based on these two displacements to obtain the total roll angle.

The longitudinal G correction unit 39 calculates the longitudinal acceleration vertical component based on the equation (5). As shown in FIG. 11 , the front/rear G correction section 39 includes a pitch angle calculation section 40 , an absolute value calculation section 41 , a sine calculation section 42 , a multiplier 43 and a sign inversion calculation section 44 . The pitch angle calculator 40 calculates the pitch angle of the vehicle body 1 based on the vehicle height, lateral acceleration, and longitudinal acceleration of the four wheels. The absolute value calculator 41 calculates the absolute value of the pitch angle. The sine calculator 42 obtains the value of the sine function for the absolute value of the pitch angle. The multiplier 43 multiplies the value output from the sin calculator 42 by the longitudinal acceleration sensor value. The sign inversion calculator 44 inverts the sign of the value output from the multiplier 43 .

As shown in FIG. 13 , the pitch angle calculator 40 includes an adder 40A that adds the pitch angle based on the displacement of the suspension device 4 and the pitch angle based on the displacement of the tires 3 . The pitch angle calculator 40 adds the pitch angles based on these two displacements to obtain the total pitch angle.

The suspension displacement roll/pitch angle calculator 45 is connected to vehicle height sensors 32FL, 32FR, 32RL, and 32RR for four wheels. The vehicle heights of the four wheels (FL vehicle height, FR vehicle height, RL vehicle height, and RR vehicle height) are input to the suspension displacement roll/pitch angle calculator 45 . As shown in FIG. 14 , the suspension displacement roll/pitch angle calculator 45 includes a suspension displacement roll angle calculator 46 and a suspension displacement pitch angle calculator 47 . A suspension displacement roll angle calculator 46 calculates a roll angle based on the displacement of the suspension device 4 . The suspension displacement pitch angle calculator 47 calculates a pitch angle based on the displacement of the suspension device 4 .

The suspension displacement roll angle calculator 46 includes subtractors 46A and 46B, an adder 46C, an average value calculator 46D, and a tread divider 46E. A subtractor 46A subtracts the vehicle height of the right front wheel (FR vehicle height) from the vehicle height of the left front wheel (FL vehicle height) to determine the vehicle height difference between the left and right wheels on the front wheel side. A subtractor 46B subtracts the vehicle height of the right rear wheel (RR vehicle height) from the vehicle height of the left rear wheel (RL vehicle height) to obtain the vehicle height difference between the left and right wheels on the rear wheel side. The adder 46C adds the left and right vehicle height difference on the front wheel side and the left and right vehicle height difference on the rear wheel side. The average value calculation unit 46D halves the left and right vehicle height difference output from the adder 46C, and obtains an average value of the left and right vehicle height difference on the front wheel side and the left and right vehicle height difference on the rear wheel side. That is, the average value calculator 46D obtains the vehicle height difference between the left and right sides of the vehicle body 1 . The tread division unit 46E divides the left-right vehicle height difference of the vehicle body 1 output from the average value calculation unit 46D by the tread Wtrd, which is the distance between the left wheel and the right wheel. As a result, the suspension displacement roll angle calculator 46 approximately obtains roll angles based on the displacements of the four suspension devices 4 .

The suspension displacement pitch angle calculator 47 includes subtractors 47A and 47B, an adder 47C, an average value calculator 47D, and a wheelbase divider 47E. The subtractor 47A subtracts the vehicle height of the left rear wheel (RL vehicle height) from the vehicle height of the left front wheel (FL vehicle height) to obtain the vehicle height difference between the front and rear wheels on the left side. The subtractor 47B subtracts the vehicle height of the right rear wheel (RR vehicle height) from the vehicle height of the right front wheel (FR vehicle height) to obtain the vehicle height difference between the front and rear wheels on the right side. The adder 47C adds the left front-rear vehicle height difference and the right front-rear vehicle height difference. The average value calculator 47D halves the front-rear vehicle height difference output from the adder 47C, and obtains an average value of the left front-rear vehicle height difference and the right front-rear vehicle height difference. That is, the average value calculator 47D obtains the vehicle height difference between the front and rear sides of the vehicle body 1 . The wheelbase dividing unit 47E divides the front-to-rear vehicle height difference of the vehicle body 1 output from the average value calculating unit 47D by the wheelbase Lwbs, which is the distance between the front wheel 2 and the rear wheel 2 . As a result, the suspension displacement roll angle calculator 46 approximately obtains the pitch angles based on the displacements of the four suspension devices 4 .

The lateral acceleration sensor 10 and the longitudinal acceleration sensor 11 are connected to the tire displacement roll/pitch angle calculator 48 . The lateral acceleration sensor value and the longitudinal acceleration sensor value are input to the tire displacement roll/pitch angle calculator 48 . As shown in FIG. 15 , the tire displacement roll/pitch angle calculator 48 includes a load transfer amount calculator 49 , a tire displacement calculator 50 , a tire displacement roll angle calculator 51 , and a tire displacement pitch angle calculator 52 . have.

The load movement amount calculator 49 calculates the movement amount of the load acting on the vehicle based on the lateral acceleration and the longitudinal acceleration. At this time, the load movement amount calculator 49 obtains the load acting on each of the four wheels of the vehicle. The tire displacement calculator 50 calculates the amount of displacement that occurs in each of the four tires 3 . As a result, the tire displacement calculator 50 calculates the left front tire displacement (FL tire displacement), the right front tire displacement (FR tire displacement), the left rear tire displacement (RL tire displacement), the right rear tire displacement (RR tire displacement). ).

The tire displacement roll angle calculator 51 calculates roll angles based on the tire displacements of the four wheels. The tire displacement pitch angle calculator 52 calculates the pitch angle based on the tire displacement of the four wheels.

As shown in FIG. 16, the tire displacement roll angle calculator 51 includes subtractors 51A and 51B, an adder 51C, an average value calculator 51D, and a tread divider 51E. The subtractor 51A subtracts the right front tire displacement (FR tire displacement) from the left front tire displacement (FL tire displacement) to obtain the vehicle height difference between the left and right front wheels. The subtractor 51B subtracts the right rear tire displacement (RR tire displacement) from the left rear tire displacement (RL tire displacement) to obtain the left and right vehicle height difference on the rear wheel side. The adder 51C adds the left and right vehicle height difference on the front wheel side and the left and right vehicle height difference on the rear wheel side. The average value calculation unit 51D halves the left and right vehicle height difference output from the adder 51C, and obtains an average value of the left and right vehicle height difference on the front wheel side and the left and right vehicle height difference on the rear wheel side. That is, the average value calculator 51D obtains the vehicle height difference between the left and right sides of the vehicle body 1 . The tread division unit 51E divides the left-right vehicle height difference of the vehicle body 1 output from the average value calculation unit 51D by the tread Wtrd, which is the distance between the left wheel and the right wheel. As a result, the tire displacement roll angle calculator 51 approximately obtains the roll angles based on the tire displacements of the four wheels.

The tire displacement pitch angle calculator 52 includes subtractors 52A and 52B, an adder 52C, an average value calculator 52D, and a wheelbase divider 52E. The subtractor 52A subtracts the left rear tire displacement (RL tire displacement) from the left front tire displacement (FL tire displacement) to obtain the front and rear vehicle height difference on the left side. The subtractor 52B subtracts the right rear tire displacement (RR tire displacement) from the right front tire displacement (FR tire displacement) to obtain the front and rear vehicle height difference on the right side. The adder 52C adds the left front-rear vehicle height difference and the right front-rear vehicle height difference. The average value calculation unit 52D halves the front and rear vehicle height difference output from the adder 52C, and obtains an average value of the left and right front and rear vehicle height differences. That is, the average value calculator 52D obtains the vehicle height difference between the front and rear sides of the vehicle body 1 . The wheelbase dividing unit 52E divides the front-to-rear vehicle height difference of the vehicle body 1 output from the average value calculating unit 52D by the wheelbase Lwbs, which is the distance between the front wheel 2 and the rear wheel 2 . Thereby, the tire displacement pitch angle calculator 52 approximately obtains the pitch angles based on the tire displacements of the four wheels.

Thus, even in the second embodiment configured in this way, substantially the same effects as those of the first embodiment can be obtained. Further, in the second embodiment, the roll angle and pitch angle are obtained based on the vehicle height of the four wheels in addition to the lateral acceleration and longitudinal acceleration. Therefore, it is possible to improve the estimation accuracy of the roll angle and the pitch angle, and to detect the correct vertical behavior.

In each of the above embodiments, the controllers 12 and 31 calculate the corrected damping coefficient Ca by lowering the upper limit of the target damping coefficient C when the relative speed V2 is low, and the command current value corresponding to the corrected damping coefficient Ca is calculated. It is configured to output I to the buffer 6 . The present invention is not limited to this, and when the roll vibration exceeds a predetermined level, the correction amount of the target damping coefficient may be decreased.

In each of the embodiments described above, the controllers 12 and 31 are configured to output the command current value I corresponding to the corrected damping coefficient Ca to the buffer 6 . The present invention is not limited to this, and the controller may calculate a corrected damping force by reducing the target damping force when the relative speed is low, and output a control signal corresponding to this corrected damping force to the shock absorber. . The controller may output a control signal corresponding to the target damping coefficient and target damping force to the shock absorber without correcting the target damping coefficient and target damping force.

In each of the above embodiments, the lateral acceleration sensor 10 detects lateral acceleration, and the longitudinal acceleration sensor 11 detects longitudinal acceleration. The present invention is not limited to this. For example, when estimating the lateral acceleration from the steering angle and the vehicle speed, the lateral acceleration detection means may include a steering angle sensor and a vehicle speed sensor (wheel speed sensor). When estimating the lateral acceleration from the yaw rate and vehicle speed, the lateral acceleration detection means may include a yaw rate sensor and a vehicle speed sensor.

When estimating the longitudinal acceleration by differentiating the vehicle speed, the longitudinal acceleration detection means may include a vehicle speed sensor. When the longitudinal acceleration is calculated using the brake hydraulic pressure, the generated torque of the power train, or an estimated value, the longitudinal acceleration detection means may include a hydraulic pressure sensor or the like.

Here, the acceleration component due to the vertical movement other than the turning influence is superimposed on the lateral acceleration sensor value and the longitudinal acceleration sensor value. Therefore, at low frequencies, sensor values detected by a lateral acceleration sensor or a longitudinal acceleration sensor are used. On the other hand, as the high-frequency lateral acceleration, the lateral acceleration estimated from the steering angle and vehicle speed or the lateral acceleration estimated from the yaw rate and vehicle speed is used. Furthermore, for the high-frequency longitudinal acceleration, an estimated value calculated using the brake fluid pressure, the generated torque of the power train, and the estimated value is used. As a result, since the acceleration can be calculated correctly, it is possible to improve the accuracy of the correction when the vertical acceleration is corrected according to the present invention. Also, the roll angle and the pitch angle may be measured by a gyro or the like.

In each of the above-described embodiments, a case where the controllers 12 and 31 that control the shock absorber 6 of the suspension device 4 based on the skyhook theory has been described as an example. The configuration may be applied to a controller that performs control, H∞ control, and the like.

In each of the above-described embodiments, the case where the force generating mechanism is the shock absorber 6 made up of a semi-active damper has been described as an example. The present invention is not limited to this, and the force generating mechanism may be an active damper (either an electric actuator or a hydraulic actuator). In each of the above-described embodiments, the case where the force generating mechanism that generates an adjustable force between the vehicle body 1 side and the wheel 2 side is configured by the damping force adjustable hydraulic shock absorber 6 has been described as an example. The present invention is not limited to this, and for example, the force generating mechanism may be configured by an air suspension, a stabilizer (Kinesus), an electromagnetic suspension, etc., in addition to the hydraulic shock absorber.

In each of the above-described embodiments, the vehicle behavior device used for a four-wheeled vehicle has been described as an example. However, the present invention is not limited to this, and can be applied to, for example, a two-wheeled or three-wheeled vehicle, a work vehicle, a truck, a bus, or the like, which is a transport vehicle.

Each of the above embodiments is an example, and partial replacement or combination of configurations shown in different embodiments is possible.

As a suspension control system based on the embodiments described above, for example, the following modes are conceivable.

A first aspect is a suspension control device for controlling an actuator interposed between a vehicle body and wheels of a vehicle. and a pitch angle calculation unit for obtaining the pitch angle using the longitudinal acceleration detection value by the longitudinal acceleration detecting means for detecting the longitudinal acceleration.

As a second aspect, in the first aspect, the vertical acceleration detection value, the roll angle, and the pitch angle are used to detect the vertical acceleration detected by vertical acceleration detection means attached to the vehicle body and detecting the vertical acceleration. It has a vertical acceleration corrector for correcting the detected acceleration value.

1 vehicle body 2 wheels 4 suspension device 5 spring 6 damping force adjustable shock absorber (shock absorber)
7 actuator 8 sprung acceleration sensor (vertical acceleration detection means)
9 unsprung acceleration sensor 10 lateral acceleration sensor (lateral acceleration detection means)
11 longitudinal acceleration sensor (longitudinal acceleration detection means)
12, 31 Controller 22, 33 Lateral Acceleration Correction Vertical Acceleration Calculation Section (Lateral G Correction Section)
23, 39 Vertical acceleration calculation section corrected for longitudinal acceleration (longitudinal G correction section)
34 roll angle calculator 40 pitch angle calculator 24 vertical acceleration corrector

Claims (2)

A suspension control device that controls an actuator interposed between a vehicle body and wheels,
a roll angle calculator for obtaining a roll angle using a lateral acceleration detection value by lateral acceleration detection means for detecting lateral acceleration;
A suspension control device, comprising: a pitch angle calculator that calculates a pitch angle using a longitudinal acceleration detection value obtained by longitudinal acceleration detection means that detects longitudinal acceleration. a vertical acceleration detection value obtained by a vertical acceleration detection means attached to the vehicle body for detecting vertical acceleration;
2. The suspension control device according to claim 1, further comprising a vertical acceleration correction section that corrects the detected vertical acceleration value using the roll angle and the pitch angle.

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