JPH08132841A - Road configuration detecting device - Google Patents

Abstract

PURPOSE: To accurately detect a road configuration by calculating or estimating the height and width of road configuration based on a calculating formula such as a regression equation based on the correlation of both values from vibration input values such as acceleration in the unspring upper and lower direction and the acceleration in the unspring front and rear direction inputted into a vehicle caused by the road configuration. CONSTITUTION: Unspring acceleration sensors 28FL, 28FR for detecting acceleration generating in a front wheel unspring are arranged in hub knuckle members 7FL, 7FR which are unspring members of front wheels 11FL, 11FR, and output signals from them are inputted into a control unit 30. Unspring upper and lower acceleration having high correlation with height and width of road projections generating in a front left and right wheel unspring is detected, a conversion signal of the difference between unspring vibration maximum value and the minimum value held as peak values of the maximum value and the minimum value immediately after vibration of the unspring acceleration value vibrating according to riding across the road projections is read in. From the maximum and minimum values, height and width of the road projections are calculated based on the multiple regression equation using car speed as a variable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road surface shape detecting device for detecting a road surface shape with unevenness, and in particular, obtains road surface information in front of a control wheel to be controlled, and controls on the basis of this road surface information. The present invention is suitable for use as a road surface information providing means for a suspension preview control device for preview controlling a suspension including an actuator such as a fluid pressure cylinder interposed between a wheel and a vehicle body.

[0002]

2. Description of the Related Art As such a road surface shape detecting device,
For example, JP-A-60-15110 previously proposed by the present applicant
Some are described in Japanese Patent Publication No. This road surface shape detecting device is, for example, specifically provided with a load sensor composed of a piezoelectric element or the like above a strut as a sensor for detecting a vibration input input to a vehicle due to the road surface shape. From the vibration input detection signal due to the road surface shape detected by the vibration input sensor, the frequency component corresponding to the unsprung resonance frequency existing in the high frequency band of about 12 to 13 Hz and the low frequency band of about 1 to 2 Hz. And the frequency component corresponding to the sprung resonance frequency existing in
Of these, the amplitude value of the frequency component corresponding to the unsprung resonance frequency is less than or equal to a preset predetermined amplitude value, and the amplitude value of the frequency component corresponding to the above-sprung resonance frequency is greater than or equal to a preset predetermined amplitude value. At this time, the road surface shape is determined to be a temporary unevenness. Further, in the road surface shape detection device, the road surface shape is, for example, flat from the energy ratio including the amplitude of the frequency component corresponding to the unsprung resonance frequency and the frequency component corresponding to the sprung resonance frequency. It is said that it is possible to judge whether it is a good road, a relatively flat gravel road, or an irregular road surface with large irregularities.

[0003]

However, in such a conventional road surface shape detecting device, it is possible to determine whether the road surface shape is a temporary unevenness or an irregular road surface having a large unevenness. However, there is a situation in which the height and width (here, the width in side view of the vehicle traveling direction) of the unevenness of the road surface shape cannot be detected.

Of course, in the suspension preview control device as described above, if there is accurate road surface information up to the height and width of the unevenness of the road surface shape, it is presumed that the information is input to the vehicle body via the control wheels. The more comfortable the estimated value of the vibration input from the road surface is, the more appropriate control force is applied to the control wheels, and the riding comfort will be improved. Therefore, conventionally, as a part of this type of road surface shape detecting device, there are many proposals using an ultrasonic sensor for detecting the uneven height of the road surface from the arrival time of the reflected wave from the road surface,
At least at present, due to problems such as noise, the road surface shape that can be detected by a traveling vehicle by the ultrasonic sensor is insufficient to be applied to the suspension preview control device.

The present invention was developed to solve these problems, and paying attention to the fact that the shape of road surface irregularities, which is a disturbance, acts as a vibration input to a vehicle with the vehicle speed as a parameter. An object of the present invention is to provide a road surface shape detecting device capable of detecting the height and width of a road surface shape.

[0006]

In order to achieve the above object, a road surface shape detecting device according to claim 1 of the present invention comprises:
As shown in the basic configuration diagram of FIG. 1, a road surface shape detecting device for detecting the road surface shape from a vibration input inputted to the vehicle due to the road surface shape, which is inputted to the vehicle due to the road surface shape. A vibration input detecting means for detecting a vibration input,
Based on at least one or both of the maximum value and the minimum value of the vibration input detection value caused by the road surface shape detected by the vibration input detection means, or the height of the road surface shape from a preset calculation formula and A road surface shape estimating means for estimating at least one or both of the widths is provided.

A road surface shape detecting device according to a second aspect of the present invention, as shown in the basic configuration diagram of FIG. 1, includes vehicle speed detecting means for detecting the vehicle speed in the front-rear direction, and the vibration input detecting means. Is an unsprung vibration input detection unit that detects an unsprung vibration input generated under the spring as a vibration input that is input to the vehicle due to the road surface shape, and the road surface shape calculation unit is the unsprung vibration input. Based on the unsprung vibration maximum-minimum difference between the maximum and minimum unsprung vibration input detection values due to the road surface shape detected by the detection means, the vehicle speed detection value detected by the vehicle speed detection means is calculated. It is characterized by comprising a road surface shape calculating means for calculating at least one or both of the height and width of the road surface shape from a regression equation set in advance as a variable.

[0008]

Therefore, in the road surface shape detecting apparatus according to claim 1 of the present invention, as shown in the basic configuration diagram of FIG. 1, the vibration input detecting means is input to the vehicle due to the road surface shape. The vibration input is detected as, for example, unsprung vertical acceleration or unsprung longitudinal acceleration, and the road surface shape estimating means detects unsprung vertical acceleration or unsprung longitudinal acceleration detected by the vibration input detecting means. As described above, based on at least one or both of the maximum value and the minimum value of the vibration input detection value due to the road surface shape, or at least one of the height and width of the road surface shape based on a preset calculation formula. Or estimate both. Here, for example, the road surface unevenness as described above is a vibration input that acts on the vehicle as a disturbance only when the vehicle is running, and as generally experienced,
For example, the larger the height of the road surface projection or the larger the width of the road surface projection, the larger the vibration input acting on the vehicle.
It is difficult to understand whether the width of the road surface projection is related to the magnitude of the vibration input acting on the vehicle from a microscopic point of view, but it is generally assumed that the vehicle speed is above a certain level. It can be seen that the time taken for the tire to pass through the possible road surface projection is much shorter than the vibration cycle at the unsprung resonance frequency, and therefore the width of the road surface projection is not a little involved in the vibration input to the vehicle. . And
If the road surface shape is at least a temporary road surface unevenness with an interval such that the tire does not continue to ride up or down continuously, the height or width of the road surface shape is It acts at least on the maximum or minimum of the vibration input detection values. That is, for example, the vibration input detection value such as the unsprung vertical acceleration or the unsprung longitudinal acceleration is not influenced by the damping coefficient of the shock absorber or the tire, the elastic coefficient of the suspension spring or the tire, the mass of the vehicle body, or the like. The maximum value and the minimum value immediately after the vibration input due to the road surface shape that has not been received are directly affected by the height and width of the road surface shape and have a high correlation coefficient, and as they increase. The maximum value of the vibration input detection value becomes larger and the minimum value becomes smaller. Therefore, the correlation between the height and width of the road surface shape and the maximum value and / or the minimum value of the vibration input is determined by, for example, the damping coefficient of the shock absorber or the tire, the elastic coefficient of the spring or the tire, the vehicle characteristics such as the mass of the vehicle body. And, in effect, the vehicle speed is also taken into consideration, and it is set in a calculation formula such as an empirical formula.
By substituting the maximum value and / or the minimum value of the vibration input detection value generated when the vehicle actually travels into the calculation formula such as the empirical formula, the height and / or width of the road surface shape can be accurately estimated. .

Further, in the road surface shape detecting device according to claim 2 of the present invention, as shown in the basic configuration diagram of FIG. 1, the unsprung vibration input detecting means provided in the vibration input detecting means is unsprung. It detects unsprung vibration input such as unsprung vertical acceleration or unsprung longitudinal acceleration that occurs in the. Such an unsprung vibration input detection value is less likely to be affected by the damping effect such as the damping coefficient of the shock absorber, the elastic coefficient of the suspension spring, or the mass of the vehicle body, and accordingly is input to the vehicle due to the road surface shape such as road surface unevenness. The vibration input will be relatively affected. On the other hand, the correlation between the maximum value and / or the minimum value of the unsprung vibration input detection value and the height or width of the road surface shape is, in other words, a high correlation coefficient with the vehicle speed as a variable as a problem of momentum. The unsprung vibration maximum-minimum difference between the maximum and minimum unsprung vibration input detection values can be regressed to the height and width of the road surface shape with a higher correlation coefficient. Therefore, based on the experimental values of the height and width of the road surface shape and the unsprung vibration maximum-minimum difference of the unsprung vibration input, a regression equation with the vehicle speed as a variable is set, and By substituting the unsprung vibration maximum-minimum value difference of the generated unsprung vibration input detection value into a regression equation according to the vehicle speed detection value detected by the vehicle speed detection means, the road surface provided in the road surface shape estimation means The shape calculation means can calculate the height and width of the road surface shape with higher accuracy.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the road surface shape detecting device of the present invention is applied to the suspension preview control device will be described below with reference to the drawings. FIG. 2 is a schematic configuration diagram of the suspension preview control device according to the present embodiment. The suspension preview control device 12 according to the present embodiment detects road surface irregularities on the front wheel side as shown in FIG. Actively predicting and controlling the suspension of the rear wheel based on the detected value, and a normal strut suspension is provided on the front wheel side. The specific configuration of the preview control device for this suspension is described in Japanese Patent Application No. 5-32 previously proposed by the present applicant.
Since it is similar or almost similar to that described in No. 8425, the same components are denoted by the same reference numerals and detailed description thereof will be omitted. In the figure, 10 is a vehicle body side member,
11FL and 11FR are front left and right wheels, 11RL and 11RR are rear left and right wheels, 12 is a preview control device, 14FL to 14RR are wheel side members, 15FL and 15FR are front and right wheel side conventional shock absorbers, 16 is a coil spring, 18RL and 18RR. Is the rear left / right wheel side hydraulic cylinder, 2
0RL and 20RR are pressure control valves, 21S is supply side piping,
21R is a return side pipe, 22 is a hydraulic pressure source, 24R is an accumulator, 26 is a vehicle speed sensor, 30 is a control unit, 32 is a throttle valve, 34 is an accumulator, and 36 is a coil spring.

Further, the vehicle body side member 10 and the rear wheel side member 1
Hydraulic cylinder 18 interposed between 4RL and 14RR
The actions of RL and 18RR are similar or almost the same as those described in the above-mentioned specification of the application, and therefore detailed description thereof will be omitted. Also, the hydraulic cylinder 18R
The basic operation of the pressure control valves 20RL and 20RR, which are actuators for driving the L and 18RR, is the same as or substantially the same as that described in the specification of the application, but in the present embodiment, the pressure control is performed. Valve 20RL, 2
0RR is composed of a so-called duty valve, and each pressure control valve 2
Drive signal C consisting of duty ratio to 0RL, 20RR
By controlling S, the hydraulic cylinders 18RL, 18
Control the control pressure P _C to the RR. Specifically, as shown in FIG. 4, when the duty ratio of the drive signal CS supplied to each pressure control valve 20RL, 20RR is a preset minimum duty ratio CS _MIN , each pressure control valve 20RL,
If the control pressure P _C supplied from the 20 RR to the hydraulic cylinders 18RL, 18RR becomes the minimum control pressure P _MIN , and if the duty ratio of the drive signal CS can be linearly increased from this state, it is proportional to the increase of the duty ratio. Control pressure P _C
Linearly increases, and when the duty ratio of the drive signal CS supplied to the pressure control valves 20RL, 20RR is a preset maximum duty ratio CS _MAX , the pressure control valves 20RL, 20RR move from the hydraulic cylinders 18RL to the hydraulic cylinders 18RL. , 18R
The control pressure P _C supplied to R becomes the maximum control pressure P _MAX .
Note that CS _N in FIG. 4 neutral duty ratio, is P _CN is neutral control pressure.

On the other hand, the unsprung members of the front wheels 11FL and 11FR, specifically, the hub knuckle member 27F shown in FIG.
L and 27FR are provided with unsprung acceleration sensors 28FL and 28FR for individually detecting accelerations (hereinafter, simply referred to as G) generated under the front wheel unsprungs. These unsprung acceleration sensors 28FL and 28FR mainly detect the vertical acceleration generated in the unsprung portion. However, in order to facilitate understanding of the explanation in the subsequent stage, the unsprung acceleration sensors 28FL and 28FR are combined in the front-rear direction. It is assumed that the acceleration can also be detected. Each of the unsprung acceleration sensors 28FL, 28FL has a zero voltage when the unsprung vertical acceleration is zero, and a positive analog voltage corresponding to the acceleration value when an upward acceleration is detected. , When the downward acceleration is detected, the unsprung vertical acceleration detection value (hereinafter also simply referred to as unsprung vertical acceleration) which is a negative analog voltage according to the acceleration value Z _GFL ,
When Z _GFR is output, zero voltage is detected when the unsprung longitudinal acceleration is zero, and when a forward acceleration is detected, a positive analog voltage corresponding to the acceleration value and a backward acceleration are detected. At this time, it is configured to output unsprung longitudinal acceleration detected values (hereinafter, simply referred to as unsprung longitudinal acceleration) X _GFL and X _GFR which are negative analog voltages according to the acceleration value.

As shown in FIG. 5, the control unit 30 includes an unsprung acceleration sensor 28i (i = FLorF).
R) unsprung vertical acceleration detection value Z output from R)
_From the unsprung acceleration conversion circuit 50 that converts an output signal of _Gi (or unsprung longitudinal acceleration detection value X _Gi ) into an unsprung acceleration unsprung vibration maximum-minimum value difference signal S _PP , and from this unsprung acceleration conversion circuit 50 The unsprung acceleration unsprung vibration maximum-minimum value difference signal S _PP output and the vehicle speed detection value V output from the vehicle speed sensor 26 are input and the control valve 20RL,
A microcomputer 44 that outputs a control amount U _i consisting of a duty ratio to 20 RR as a control signal, and the control amount control signal U _{i that} is D / A converted and output from the microcomputer 44 are supplied to these. A drive circuit 46i for converting the duty ratio drive signal CS _i for the pressure control valves 20RL and 20RR. It should be noted that there are substantially two unsprung acceleration sensors 28FL, 28FR, and for example, each unsprung acceleration sensor 28FL, 28FR is
Unsprung vertical acceleration detection values Z _GFL , Z from 8FR
_{When only the GFR} or the unsprung longitudinal acceleration detection values X _GFL and X _GFR are subjected to the arithmetic processing of FIG. 8 described later,
At least two unsprung acceleration conversion circuits 50 composed of analog hardware circuits are required in parallel, and further unsprung vertical acceleration detection values Z _GFL , Z _GFR and unsprung acceleration from each unsprung acceleration sensor 28FL, 28FR. When performing the calculation process of FIG. 8 to be described later on all of the longitudinal acceleration detection values X _GFL and X _GFR , four unsprung acceleration conversion circuits 50 are required in parallel, but here are representative thereof. Only one of these will be described in detail.

Here, the microcomputer 44 includes an input side interface circuit 44a having at least an F / V conversion function and an A / D conversion function, an output side interface circuit 44b having a D / A conversion function, and a microprocessor unit MPU. Processing unit (CPU) 44c including
And a storage device 44d including a RAM and a ROM. The input interface circuit 44a includes a vehicle speed detection value V from the vehicle speed sensor 26 and an unsprung acceleration conversion circuit 5.
The unsprung acceleration unsprung vibration maximum-minimum value difference conversion signal S _{PP from 0} is input, and the output side interface circuit 44b.
Outputs a control command value U _i for each pressure control valve 20 _i .

Further, the arithmetic processing unit 44c executes an arithmetic processing (not shown), and at every predetermined sampling time ΔT (for example, 5 msec.), The vehicle speed V from the vehicle speed sensor 26 and the spring according to the arithmetic processing of FIG. An unsprung acceleration unsprung vibration from the lower acceleration conversion circuit 50 calculates a projection height X ₁ and a projection width X ₂ of a road surface shape on each of the front left and right wheel loci according to the maximum-minimum value difference conversion signal S _PP. As a rear-wheel vibration input estimation value that will be input to each of the rear left and right wheels from the differential value of the road surface shape, etc., a differential value of the road surface displacement on each of the front left and right wheel loci is calculated, and this differential value of the road surface displacement is calculated. A predictive control amount is calculated based on the vehicle speed detection value, a delay time between the front and rear wheels is calculated based on the vehicle speed detection value, and the rear wheel side pressure control valves 20R, 20 are calculated based on the predictive control amount when the delay time becomes zero.
The control amount U _i to the RR is calculated, and this control amount U _i is output as a control signal to the rear wheel side pressure control valves 20R and 20RR.

Further, the storage device 44d stores in advance maps, regression equations, programs and the like required for the arithmetic processing of the arithmetic processing device 44c, and the preview control amount calculated at each predetermined sampling time ΔT. A shift register area for storing a predetermined number while sequentially shifting with the delay time is formed, and a calculation result required in the calculation process of the calculation processing device 44c is sequentially stored.

Before explaining the unsprung acceleration conversion circuit 50, the principle of calculating the height and width of the road surface shape in this embodiment will be described. First, the front wheel with pneumatic tires 1 having a conventional conventional suspension
When 1FL and 11FR pass over a road surface protrusion having a height X ₁ and a width X ₂ in a side view as shown in FIG. 6a, the unsprung vertical acceleration Z _Gi and / or the unsprung acceleration accompanying the unsprung vibration as shown in FIG. 6b. Unsprung longitudinal acceleration X _Gi (Unit is g (gravit
y, gravitational acceleration)) occurs. The unsprung vertical acceleration Z _Gi and / or the unsprung longitudinal acceleration X _Gi associated with this unsprung vibration is a transient vibration of the road surface protrusions, so that unsprung resonance of around 11 to 12 Hz occurs. It is considered to correspond to the frequency, however, the shock absorbers 15FL and 15FR, the damping coefficient of the tire, the elastic coefficient of the coil spring 16 and the tire, the damping force due to the sprung mass, and the like are damped with the passage of time and converge. To do.

By the way, for overcoming such a road surface protrusion
Accompanying unsprung vertical acceleration Z_GiAnd / or unsprung front and rear
Directional acceleration X_GiThe initial value of is the shock absorber 15
Damping coefficient of FL, 15FR and bullet of coil spring 16
Less susceptible to damping effects such as sex factor or body mass,
Therefore, the height X of the road protrusion shown in FIG. ₁
Or width X₂In the vibration input input to the vehicle according to
However, the impact will be relatively straightforward. here
Therefore, for example, the road surface protrusions as described above are
It is a vibration input that acts on the vehicle as a disturbance,
As you will see, for example, the height X of the road protrusion₁Is large
Or the width X of the road protrusion₂The larger the
The vibration input that acts is also large. Width X of road protrusion₂But the vehicle
It is slightly related to the magnitude of the vibration input that acts on
It is difficult to understand visually, but the vehicle speed is above a certain level
Then, macroscopically, the tires continuously ride on the road surface protrusion.
Thinking about not continuing or getting on and off
The time it takes for a tire to pass through a certain road surface protrusion is
It is much shorter than the vibration period at the unsprung resonance frequency.
Therefore, the width of the road protrusion is also small for vibration input to the vehicle.
It turns out that they are involved.

On the other hand, the maximum and / or minimum value of the unsprung vertical acceleration Z _Gi and / or the unsprung longitudinal acceleration X _Gi which are the unsprung vibration input detection values due to such transient passage of the road protrusion. Is the value immediately after the unsprung vibration input due to the road surface projection is input. Therefore, for example, the damping coefficient of the shock absorber or the tire, the elastic coefficient of the suspension spring or the tire, the damping factor of the vehicle body mass, etc. No or not so much, and accordingly, the maximum and / or minimum values of the unsprung vertical acceleration Z _Gi and / or the unsprung longitudinal acceleration X _Gi and the height X ₁ and width X _{2 of the} road surface shape. It can be said that is a problem of momentum in which the vehicle speed V detected by the vehicle speed sensor 26 is a variable. Therefore, the absolute value of the difference between the maximum value and the minimum value of the unsprung vertical acceleration Z _Gi is defined as the unsprung vibration maximum-minimum value difference A _PP, and the height X ₁ and the width X _{2 of the} road surface protrusion are set. With various changes, run the same vehicle at a predetermined vehicle speed V,
FIG. 7 is a plot of the maximum-minimum value difference A _PP of unsprung vibration when the vehicle passes over the road surface projection and the road surface projection height X ₁ . Of these, Figure 7a shows the same vehicle at 30 mi / h.
FIG. 7b shows the same vehicle running at 50 mile / hr per hour.
As is clear from the figure, the unsprung vibration maximum-minimum value difference A _PP and the road surface projection height X ₁ and width X ₂ have a high correlation coefficient (contribution rate), which is called statistical analysis. It can be seen that there is a strong positive correlation. Further, according to the experiment, when the absolute value of the difference between the maximum value and the minimum value of the unsprung longitudinal acceleration X _Gi is the unsprung vibration maximum-minimum difference B _PP , or the unsprung vertical acceleration Z _Gi or unsprung longitudinal acceleration X _Gi
When the absolute value of the difference between the maximum value and the zero value is the unsprung vibration maximum-zero value difference A _P-0 , B _P-0 , or the unsprung vertical acceleration Z _Gi or unsprung longitudinal acceleration X. The absolute value of the difference between the zero value and the minimum value of _Gi is the unsprung vibration zero-minimum value difference A _0-P , B _0-P
In the case of, the same correlation was exhibited, and the high contribution rate R ² was exhibited in each case. Therefore, it is shown in Table 1 below together with the multiple regression equation.

[0020]

[Table 1]

In this embodiment, the unsprung vibration maximum-minimum value difference A _PP and / or the unsprung front-rear acceleration X of the unsprung vertical acceleration Z _Gi having a particularly high contribution rate among the unsprung vibration difference values. _Although the height X ₁ and the width X ₂ of the road surface projection are calculated and set using the unsprung vibration zero-minimum value difference B _PP of _Gi, the map shown in FIG. 7 is selected according to the vehicle speed detection value V. A microcomputer is used to set and extract the multiple regression equation shown in Table 1 by interpolation or the like, or to calculate and set the height X ₁ and the width X ₂ of the road protrusion according to the multiple regression equation. However, on the contrary, the analog hardware circuit is not realistic because the configuration becomes too complicated. However, since the unsprung vertical acceleration Z _Gi and / or the unsprung forward / backward acceleration X _Gi due to the unsprung vibration input accompanying the overcoming of the road protrusion is a continuous value including the maximum value and the minimum value thereof, it is a discrete value. In a microcomputer capable of performing only arithmetic processing, there is a possibility that the detection or calculation of the unsprung vibration maximum-minimum value difference A _PP , B _PP becomes inaccurate. Therefore, in this embodiment, the height X ₁ and the width X _{2 of the} road surface projection are determined by a microcomputer.
In order to make the calculation setting of the above-mentioned more accurate, it is possible to output the unsprung vibration maximum-minimum value difference A _PP , B _PP read by the microcomputer by an analog hardware circuit. The acceleration conversion circuit 50.

This unsprung acceleration conversion circuit 50 is
With each unsprung acceleration sensor 28i of the wheels 11FL and 11FR
Unsprung vertical acceleration Z detected_GiAnd / or unsprung
Longitudinal acceleration X_GiEnter noise such as white noise
The unsprung resonance frequency
A bandpass composed of frequency components corresponding to
Unsprung acceleration signal S_BPGOutput bandpass filter
Filter 51 and the band pass unsprung acceleration signal S_BPGof
Positive value unsprung acceleration signal S by rectifying a negative value signal_{+ H}Out
Force half-wave rectifier 52a and the positive-value unsprung acceleration signal
S_{+ H}Holds the maximum value (peak value) of positive acceleration
Degree maximum value signal S_{+ P}And a reset signal from the outside
S_RESETBy the unsprung acceleration maximum value signal S_{+ P}Lyce
Adjustable peak hold circuit 54a and band pass
Unsprung acceleration signal S_BPGRectifies the positive value signal of
Unsprung acceleration signal S_-HHalf-wave rectifier 52a that outputs
And the negative unsprung acceleration signal S_-HThe negative of the sign of
Value unsprung acceleration inversion signal S_{-H R}Inverter 53 for outputting
And the negative unsprung acceleration inversion signal S_-HRMaximum of (actual
Qualitatively, negative unsprung acceleration Z_Gi, X_GiIs the minimum of
Peak value) and hold negative negative unsprung acceleration minimum value signal S
_-PAnd a reset signal S from the outside_RESETBy
The unsprung acceleration minimum value signal S_-PResettable peak
Hold circuit 54a and the maximum positive unsprung acceleration value
Signal S_{+ P}And negative unsprung acceleration minimum value signal S _-PAnd add
The unsprung acceleration unsprung vibration maximum-minimum value difference conversion signal
No. S_PPAnd an adder 55 that outputs

The operation of the unsprung acceleration conversion circuit 50 will be briefly described. The unsprung vertical acceleration Z _Gi and / or the unsprung forward / backward acceleration X _Gi until reaching the road surface projection as described above is zero or substantially zero. At the same time when the road surface projection is overcome, the unsprung vertical acceleration Z _Gi and / or the unsprung longitudinal acceleration X _Gi increases in the positive region, and eventually decreases in the positive region and then decreases in the negative region. Then, the phenomenon of increasing in the positive region and then increasing in the positive region is repeated, but the unsprung vertical acceleration Z _Gi and / or the unsprung longitudinal acceleration X _Gi is the normal damping shown in FIG. 6b. It is assumed that the curve gradually attenuates and converges according to the curve. Therefore, the band-pass unsprung acceleration signal S _{BPG that} has become a frequency band corresponding to or substantially corresponding to the unsprung resonance frequency by the bandpass filter 51 is the positive unsprung acceleration signal S ₊ by the one half-wave rectifier 52a. _H , and the other half-wave rectifier 52b produces a negative unsprung acceleration signal S _-H . This negative unsprung acceleration signal S _-H becomes
The negative unsprung acceleration inversion signal S- _HR is inverted by the inversion device 53. Here, since the unsprung vertical acceleration Z _Gi and / or the unsprung longitudinal acceleration X _Gi due to riding over the road surface protrusion first increases in the positive region, the positive unsprung acceleration signal S _{+ H} is The negative unsprung acceleration signal S _-H
Alternatively, it can be said that the phase is advanced from the negative unsprung acceleration inversion signal S- _HR . Therefore, the positive unsprung acceleration maximum value signal S output from the one peak hold circuit 54a.
_{+ P} rises before the negative unsprung acceleration minimum value signal S _-P output from the other peak hold circuit 54b, and the unsprung vertical acceleration Z _Gi and / or the unsprung longitudinal acceleration is increased. The value is held at a certain peak value corresponding to the maximum value of X _{Gi, and} the negative unsprung acceleration minimum value signal S _-P rises after that, and the unsprung vertical acceleration Z _Gi and / or unsprung forward and backward directions It is held at a certain peak value corresponding to the minimum value of the acceleration X _Gi . Therefore, the unsprung vibration maximum-minimum value difference conversion signal S _PP output from the adder 55 increases in two steps with the passage of time as shown in FIG. The minimum value difference conversion signal S _{P- P} becomes the unsprung vibration maximum-minimum value difference A _PP , B _PP .

Next, using the vehicle speed V from the vehicle speed sensor 26 and the unsprung vibration maximum-minimum value difference conversion signal S _PP from the unsprung acceleration conversion circuit 50, the arithmetic processing unit 44c of the microcomputer 44 uses it. The principle of the arithmetic processing to be executed for detecting the road surface shape will be described. In the microcomputer 44, the unsprung vibration maximum-minimum value difference (hereinafter, also simply referred to as p-p value) A as described above.
After detecting the _PP and selecting the control map from the vehicle speed V, the relevant regression equation is extracted and the height X ₁ and width X _{2 of the} road protrusion are extracted.
And calculate. At this time, the problem is that the pp value A
_These are the _PP detection timing and the peak hold reset timing of the unsprung vibration maximum-minimum value difference conversion signal S _PP . First, as described above, the unsprung vibration maximum-minimum value difference conversion signal S _PP should increase in the positive direction when overcoming the road protrusion, and the unsprung vertical acceleration Z _Gi and / or
Alternatively, the unsprung longitudinal acceleration X _Gi should vibrate at a cycle corresponding to or substantially corresponding to the unsprung resonance frequency of the vehicle, so that a cycle corresponding to this unsprung resonance frequency is defined as an unsprung resonance cycle T. After the unsprung vibration maximum-minimum value difference conversion signal S _PP starts to rise in the positive direction, the unsprung vibration maximum-minimum value is approximately 3/4 times (3/4) T of the unsprung resonance period. The increase in the second stage of the difference conversion signal S _PP should be completed. Therefore, the unsprung vibration maximum-minimum value difference conversion signal S _PP is a positive dead zone threshold value S.
_{When P-P0} is _exceeded , the counter CNT starts incrementing, and this counter CNT becomes 3 / of the unsprung resonance period.
Predetermined count value CN that becomes larger than quadruple value (3/4) T
When the unsprung resonance period T is substantially equal to or greater than T ₀ , the unsprung vibration maximum-minimum value difference conversion signal S _{PP is changed} to the pp value A.
Set to _PP . When the unsprung vibration maximum-minimum value difference conversion signal S _PP does not exceed the positive dead-zone threshold value S _P-P0 , a reset signal S _RESET is output to the peak hold circuits 54a and 54b, and the Avoid setting the peak hold value, which decreases in the negative direction due to the influence, so that the road surface shape that is not the road surface projection is not misjudged.

As described above, the unsprung vibration caused by overcoming the road surface protrusion is, for example, when the unsprung vibration occurs over the next road surface projection after the unsprung vibration occurs over the previous road surface projection overrun. Occurrence or unpredictable,
Also, the time required to get over the road protrusion at normal vehicle speed is
Since it is much shorter than the unsprung resonance period, the unsprung vibration maximum-minimum value difference conversion signal S _{PP is} converted to the pp value A.
_{When PP} is set and the height X ₁ and width X ₂ of the road surface projection are calculated, the unsprung vibration maximum-minimum value difference conversion signal S _PP , that is, the positive unsprung acceleration signal S _{+ H} and the negative value, is calculated as quickly as possible. I want to reset the hold of the unsprung acceleration signal S _-H to prepare for the next unsprung vibration that occurs when the road surface projection is passed over. However, as described above, the unsprung resonance period T
Unsprung vibration maximum-minimum value difference conversion signal S _PP is p
When the hold of the positive unsprung acceleration signal S _{+ H} and the negative unsprung acceleration signal S _-H is reset after setting -p value A _PP , the next unsprung resonance period T that is normally damped is reset. Since the unsprung vertical acceleration Z _Gi and / or the unsprung longitudinal acceleration X _{Gi of the above} will be peak-held as it is, the existence of the unsprung vibration maximum-minimum value difference conversion signal S _PP is output. There is a possibility to calculate the height X ₁ and the width X ₂ of the road protrusion. Therefore, in the present embodiment, the damping coefficient appearing in the normal damping curve shown in FIG. 6b is f based on the damping coefficient C of the shock absorber, the elastic coefficient K of the coil spring, the elapsed time t, and the like.
Set with (C, K, t), and set this to the previous value A of the pp value.
The estimated current value A _{PP (n) OB} of the _PP value is calculated and set by multiplying _{PP (n-1)} , and the detected current value A of the _PP value is set.
_{When PP (n)} is less than or equal to this estimated current value A _{PP (n) OB} , the height X ₁ and the width X ₂ of the road surface projection are not calculated.

In accordance with the above basic principle, the arithmetic processing for calculating the road surface shape executed by the microcomputer 44 of the control unit 30 will be described with reference to the flowchart of FIG. The calculation process of FIG. 8 is executed as a timer interrupt process for each preset predetermined sampling time (for example, 5 msec.) ΔT, for example, as a minor program of a calculation process for preview control of the rear wheel suspension. . For this arithmetic processing, a large amount of control maps and regression equations based on vehicle experimental values as shown in FIG. 7 are stored in the storage device 44d.
In the arithmetic processing of No., a step for communication is not provided, but a control map and a regression equation which are required at any time in response to a call from the arithmetic processing unit 44c are communicated to a buffer or the like of the arithmetic processing unit 44c. It is assumed that the calculation result and each detection data in the device 44c are sequentially updated and stored in the storage device 44d.

In the arithmetic processing of FIG. 8, first, step S
In step 1, the unsprung vibration maximum-minimum value difference conversion signal (hereinafter, also simply referred to as p-p signal) S _PP from the unsprung acceleration conversion circuit 50 is read. Next, the process proceeds to step S2, and it is determined whether or not the p-p signal S _{P- P} read in the step S1 is equal to or more than the preset positive dead zone threshold value S _P-P0 , The pp signal S _PP is a dead zone threshold S _P-P0.
When it is above, it transfers to step S3, and when that is not right, it transfers to step S4.

In step S3, the counter CNT is incremented and then the process proceeds to step S5. In step S5, the count value of the counter CNT is determined whether the at preset predetermined count value CNT ₀ or more, step if the count value of the counter CNT is a predetermined count value CNT ₀ or more The process proceeds to S6, and if not, the process returns to the main program.

In the step S6, the step S1
The pp signal S _PP read in is set to the current value A of the pp value.
_After setting to _{PP (n)} , the process proceeds to step S7. In step S7, the damping ratio f is set to the previous value A _{PP (n-1)} of the pp value updated and stored in the storage device 44d.
Multiplying by (C, K, t), the estimated current value A of the pp value A
_After calculating _{PP (n) OB} , the process proceeds to step S8.

In the step S8, the step S6
The current value A _{P- P (n)} of the p-p value set in step S7 is calculated and the estimated current value A _{PP (n) OB of} the p-p value set in the step S7.
It is determined whether or not the above, and the current value A of the pp value concerned.
_{If PP (n)} is equal to or greater than the estimated current value A _{PP (n) OB of the} pp value, the process proceeds to step S9, and if not, the process proceeds to step S10.

In step S9, the vehicle speed sensor 2
After reading the vehicle speed V detected in step 6, step S11
Move to In step S11, a control map corresponding to the vehicle speed V read in step S9 is selected according to a minor program (not shown), and then the process proceeds to step S12.

In step S12, a regression equation corresponding to the current value A _{PP (n)} of the pp value is extracted from the control map selected in step S11 according to a minor program (not shown ₎ , and then in step S13. Transition. In the step S13, since the calculated present value A _{PP (n)} road surface projection height X ₁ and road surface projection width X ₂ that satisfies the p-p value according regression equation which is extracted in the step S12, the Control goes to step S10.

In step S10, the pp value is
This time value A_{PP (n)}Is the last value A of p-p _{PP (n-1)}Remember as
After updating and storing in the device 44d, the process proceeds to step S4.
To go. In step S4, the peak hold
Reset signal S on paths 54a and 54b_RESETOr output
Then, the process proceeds to step S14.

In step S14, the counter CNT
After clearing, return to the main program. According to this arithmetic processing, after the unsprung vibration occurs due to the road protrusion of each of the front left and right wheels, the height X ₁ and the width X ₂ of the road protrusion are increased after the unsprung resonance period T. Since it can be detected with accuracy, if the road surface projection shape is used to perform the preview control of the rear wheel suspension (not shown), the control amount of the rear wheel suspension is optimally controlled to further improve the riding comfort. can do.

From the above, it is considered that the above embodiment is an implementation of the road surface shape detecting device according to claims 1 and 2 of the present invention, and the unsprung acceleration sensor 28F shown in FIGS. 2 and 5.
L, 28FR, the unsprung acceleration conversion circuit 50 of FIG. 5, and step S1 of the calculation processing of FIG. 8 correspond to the unsprung vibration input detection means and the vibration input detection means of the road surface shape detection device of the present invention. The vehicle speed sensor 26 of FIGS. 2 and 5 and step S9 of the arithmetic processing of FIG. 8 correspond to the vehicle speed detecting means, and the regression equation shown in Table 1, the control map shown in FIG. 7, and the steps S11 to S11 of the arithmetic processing of FIG. S13 corresponds to the road surface shape calculation means, and the whole calculation process of FIG. 8 and FIG.
The control unit corresponds to the road surface shape estimating means.

In the arithmetic processing of FIG. 8, only the case where the height X ₁ and the width X ₂ of the road surface projection are calculated and set based on the pp value A _PP obtained from the unsprung vertical acceleration Z _Gi will be described. However, if sufficient calculation accuracy of the height X ₁ and the width X ₂ of the road surface protrusion cannot be obtained from only this one-direction acceleration signal, another acceleration signal, that is, the unsprung longitudinal acceleration X _Gi It is also possible to obtain the height X ₁ and the width X ₂ of the road surface projections on the basis of the pp value A _PP obtained from the above and to match them to improve their detection accuracy.

Further, in the above embodiment, the arithmetic processing and the processing of FIG.
And the control unit in Fig. 5 is accompanied by unsprung vibration.
Acceleration Z_Gi, X_GiMaximum-minimum value difference (pp value)
A_PP, B _PPBased on the height of the road protrusion X₁And width X
₂Although only the case of calculating
In the surface shape detection device, as described above, for example, unsprung vibration
Acceleration Z associated with_Gi, X_GiMaximum value-zero difference (p-0 value) A
_P-0, B_P-0Or zero-minimum value difference (0-p value) A_0-P, B
_0-PBased on the height of the road protrusion X₁And width X₂And calculate
In any case, those regression equations have a high correlation coefficient.
To have a calculated road surface projection height X₁And width
X₂Is also highly accurate.

In the above embodiment, the case where the control unit 30 is composed of a microcomputer has been described, but the present invention is not limited to this.
It goes without saying that electronic circuits such as shift registers and arithmetic circuits may be combined. Further, in the above embodiment, the case where the working oil is applied as the working fluid has been described, but the working fluid is not limited to this, and any working fluid may be applied as long as the fluid has a low compression rate.

In the above embodiment, the rear wheel suspension is actively foreseen and controlled, but the present invention is
It is also applied to semi-active preview control with a variable damping force shock absorber. Further, in the above-mentioned embodiment, only the case where the height or width of the detected road surface shape is applied to the preview control of the rear wheel suspension is described in detail, but the height or width of the road surface shape detected by the road surface shape detection device of the present invention is Width,
It can be applied to all vehicle motion control devices.

[0040]

As described above, according to the road surface shape detecting device of the present invention, a vehicle having a high correlation coefficient with the height and width of the road surface shape and having the vehicle speed as a variable is caused by the road surface shape. A configuration for calculating or estimating the height or width of the road surface shape from a vibration input detection value such as unsprung vertical acceleration or unsprung longitudinal acceleration that is input in accordance with a calculation formula such as a regression formula based on a correlation between the two. Therefore, the height and width of the road surface shape can be calculated or estimated with high accuracy.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing a schematic configuration of a road surface shape detection device of the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment in which the road surface shape detecting device of the present invention is applied to a preview control device for a rear wheel suspension.

FIG. 3 is a schematic diagram showing a preview control concept of the preview control device for the rear wheel suspension shown in FIG.

FIG. 4 is a characteristic diagram showing a relationship between a drive signal and control pressure of the pressure control valve shown in FIG.

5 is a block diagram showing an example of a control unit shown in FIG.

FIG. 6 is a diagram illustrating the principle of the road surface shape detecting device of the present invention.

FIG. 7 is an explanatory diagram of a regression equation used in the road surface shape detecting device of the present invention.

8 is a flowchart showing a calculation process for detecting a road surface shape, which is executed by a microcomputer of the control unit shown in FIG.

[Explanation of symbols]

 10 is a member on the vehicle body side. 11FL to 11RR are wheels. 12 is a suspension preview control device. 18RL and 18RR are hydraulic cylinders. 20RL and 20RR are pressure control valves. 22 is a hydraulic pressure source. 26 is a vehicle speed sensor. 28FL and 28FR is an unsprung acceleration sensor. 30 is a control unit. Is a microcomputer 50 is an unsprung acceleration conversion circuit

Claims (2)

[Claims] 1. A road surface shape detecting device for detecting a road surface shape from a vibration input inputted to a vehicle due to a road surface shape, wherein the vibration input inputted to the vehicle due to the road surface shape is detected. Vibration input detection means, based on at least one or both of the maximum value and the minimum value of the vibration input detection value due to the road surface shape detected by the vibration input detection means, from the preset calculation formula A road surface shape detecting device comprising: a road surface shape estimating means for estimating at least one or both of a height and a width of the road surface shape. 2. An unsprung vibration input generated under the spring as a vibration input to the vehicle due to the road surface shape, comprising vehicle speed detection means for detecting a vehicle speed in the front-rear direction of the vehicle. An unsprung vibration input detection means for detecting, the road surface shape calculation means, between the maximum value and the minimum value of the unsprung vibration input detection value resulting from the road surface shape detected by the unsprung vibration input detection means. Based on the unsprung vibration maximum-minimum value difference, at least one or both of the height and width of the road surface shape from a preset regression equation with the vehicle speed detection value detected by the vehicle speed detection means as a variable. The road surface shape detecting device according to claim 1, further comprising a road surface shape calculating means for calculating the road surface shape.