JPH07102767B2 - Damping force controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention uses the sprung mass absolute velocity estimated by an optimum filter constructed based on a dynamic model of a vehicle suspension state to provide optimum damping for the vehicle suspension state. The present invention relates to a damping force control device that realizes force and is effective in improving ride comfort.

[Prior Art] As a method of blocking the vertical road surface disturbance transmitted from the unsprung to the sprung and suppressing the absolute displacement in the vertical direction on the spring while the vehicle is traveling, the Skyhook principle has been conventionally used. Are known. Furthermore, based on the skyhook principle, the damping force of the shock absorber is minimized from the absolute velocity in the vertical direction on the vehicle spring and the relative velocity in the vertical direction on the spring to minimize the absolute displacement in the vertical direction on the spring. The Carnop theory, which controls semi-actively, was also proposed. As a technique for controlling the vertical displacement of a vehicle in accordance with such a theory, for example, "Suspension control device" (Shokai Sho
63-93203) and the like have been proposed. In other words, from the absolute velocity in the vertical direction on the spring and the relative velocity in the vertical direction on the spring, the damping force of the shock absorber is increased when they are in phase, while the damping force is controlled to be low when they are in the opposite phase. It suppresses the road surface disturbance transmission to the spring.

[Problems to be Solved by the Invention] By the way, in order to control the damping force by applying the Skyhook principle or the Karnop theory, the absolute velocity in the vertical direction on the spring and the relative velocity in the vertical direction on the spring are detected. There is a need. Therefore, in the prior art, the detection signal of an acceleration sensor, which is arranged on the floor of the vehicle body and detects the vertical acceleration of the vehicle body, is time-integrated to calculate the absolute velocity in the vertical direction on the spring and the relative displacement sensor. The relative speed on the sprung was detected by. However, two types of sensors, an acceleration sensor and a relative displacement sensor, are required. Moreover, neither the detection accuracy of the detection signal of the acceleration sensor nor the calculation accuracy of the time integration calculation is sufficient, so that the sprung absolute speed cannot be accurately measured. There was a problem that it could not be detected.

Therefore, since the sprung mass absolute speed with sufficient accuracy cannot be obtained, the control accuracy of the damping force control based on this also decreases,
There is also a problem that it is extremely difficult to realize appropriate damping force control that effectively applies the Skyhook principle and the Karnop theory.

The present invention accurately provides the vertical sprung mass absolute velocity of a vehicle, which is extremely difficult to detect, based on the dynamic model of the vertical motion of the vehicle, by only providing one type of detector capable of measuring the damping force. It is an object of the present invention to provide a damping force control device that can estimate and apply the Skyhook's principle and the Karnop theory appropriately by using the estimated absolute sprung velocity.

[Means for Solving the Problems] The present invention made to achieve the above object is, as illustrated in FIG. 1, interposed between a sprung portion and an unsprung portion of a wheel portion of a vehicle, Damping force changing means M1 for changing the damping force acting between the sprung portion and the unsprung portion in accordance with a command from the outside, and damping force detecting means M2 for detecting the damping force equivalent amount of the wheel portion.
A sprung relative speed calculating means M3 for calculating a relative speed with respect to a road surface on a spring according to the damping force detected by the damping force detecting means M2, and a parameter determined based on a dynamic model of the vertical movement of the vehicle. Using the sprung mass absolute speed estimating means M4 for estimating the sprung mass absolute speed of the vehicle according to the damping force detected by the damping force detecting means M2, and the spring estimated by the sprung mass absolute speed estimating means M4. The target damping force of the wheel portion of the vehicle is determined based on the upper absolute velocity and the sprung relative velocity calculated by the sprung relative velocity calculating means M3, and the damping force of the wheel portion of the vehicle is changed to the target damping force. Control means M5 for outputting a command to the damping force changing means M1
The gist of the present invention is a damping force control device characterized by including:

[Operation] The damping force control device of the present invention, as illustrated in FIG.
The damping force detection means M2 detects the damping force of the wheel portion of the vehicle. In accordance with this damping force, the sprung relative speed calculation M3 calculates the relative speed with respect to the road surface on the spring. Here, the sprung mass absolute velocity estimating means M4 uses a parameter determined based on a dynamic model of the vertical movement of the vehicle, and the sprung mass of the vehicle according to the damping force detected by the damping force detecting means M2. Estimate absolute velocity. The target damping force of the wheel portion of the vehicle is determined based on the estimated absolute sprung velocity and the sprung relative velocity calculated by the sprung relative velocity calculating means, and the damping force of the wheel portion of the vehicle is reduced to the target damping force. The control means M5 outputs a command to change to force to the damping force changing means M1.
In accordance with this command, the damping force changing means M1 provided between the sprung portion and the unsprung portion of the wheel portion of the vehicle works to change the damping force acting between the sprung portion and the unsprung portion.

That is, only the damping force is measured and derived using the sprung absolute velocity estimated from the damping force and the sprung relative velocity calculated from the damping force using parameters determined based on the dynamic model of the vertical movement of the vehicle. The control is performed so as to realize the optimum target damping force.

Therefore, the damping force control device according to the present invention is based on the sprung relative speed and the dynamic model of the vehicle, and has the sprung force accurately estimated according to the measured damping force by only one type of detecting means capable of measuring the damping force. From the absolute speed, it works to exert the optimum damping force for the suspended state of the vehicle.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 shows a system configuration of a shock absorber control device which is an embodiment of the present invention.

As shown in the figure, the shock absorber control device 1 is
It is composed of damping force variable type shock absorbers 2, 3, 4, 5 arranged for each of the four wheels, and an absorber control computer 6 for controlling these.

The damping force variable type shock absorbers 2, 3, 4, and 5 have the same structure, so the damping force variable type shock absorber 2
Will be described as an example. The damping force type shock absorber 2 is interposed between the lower arm 2a of the left front wheel and the vehicle body 7, and the shock absorber 2b and the shock absorber 2b are capable of continuously changing the damping coefficient by adjusting the flow passage area of the absorber oil. An absorber control actuator 2d for changing the damping coefficient of the coil spring 2c and the shock absorber 2b, which are installed together with the shock absorber 2b, under the control of the absorber control computer 6 is provided.

The shock absorber control device 1 includes a damping force sensor 1 as a detector, which is composed of a piezoelectric element incorporated in the vertical acting force transmitting portion of each damping force type shock absorber 2, 3, 4, or 5.
Equipped with 1,12,13,14.

Absorber control computer 6 is CPU6a, ROM6
b, RAM 6c, and backup RAM 6d are mainly configured as a logical operation circuit, which is connected to an input / output unit 6f via a common bus 6e to perform input / output with the outside. The detection signal of each sensor is input to the CPU 6a via the input / output unit 6f, while the CPU 6a outputs a control signal to the absorber control actuators 2d, 3d, 4d, 5d via the input / output unit 6f.

Next, from the damping force y detected by the damping force sensors 11, 12, 13, and 14, the optimum estimated value of the sprung absolute velocity is obtained. And the optimal estimate of this sprung absolute velocity A control system for obtaining the target damping coefficient C ^* based on the above will be described based on the block diagram of FIG. Note that FIG. 3 is a diagram showing a control system and does not show a hardware configuration. The control system shown in FIG. 3 is actually realized as a discrete time system by executing the series of programs shown in the flowcharts of FIGS. 5 (1) and 5 (2).

As shown in FIG. 3, the signal generator P1 receives a signal under the influence of system disturbance (road disturbance) v, which is a random variable. Shows the process that changes with the passage of time. here,
signal It is a signal that takes a two-dimensional vector value, and has the sprung absolute displacement x and the sprung absolute velocity as its elements.

This direct undetectable signal The observation noise W, which is a random variable, is added through the observation unit P2, and the damping force y that can be directly detected is obtained.

The Kalman filter P3 receives this damping force y, Is a linear system whose output is.

The damping force y output from the observation unit P2 is the relative velocity calculation unit P4.
Then, it is divided by the damping coefficient C at that time and converted into the sprung relative velocity (-0).

This sprung relative speed (-0) is calculated by the relative displacement calculation unit P5.
Are integrated and converted into a sprung relative displacement (x−x0).

In addition, the constant calculation unit P6 determines the damping at that time from the sprung relative speed (-0) calculated by the relative speed calculation unit P4 and the sprung relative displacement (x-x0) calculated by the relative displacement calculation unit P5. Both limit values of coefficient C (CH1P, CH1N, CH2P, CH2N, CL
P, CL1N, CL2N) and the spring constant K are calculated, and these values are output in order to update the coefficient matrix of the Kalman filter P3 as needed.

The control amount calculation unit P7 includes the sprung relative speed (−0) calculated by the relative speed calculation unit P4, Optimum value of absolute sprung velocity, which is a factor of When 1 time before the target damping coefficient C ^* in sequence, to calculate the target damping coefficient of the current processing time of C ^*, the signal generating unit P1, the observation unit
Output to P2 and relative speed calculator P4.

The hardware configuration of the shock absorber control device 1 and the control system realized by executing the damping force control process described later have been described above. Therefore, next, the construction of a dynamic physical model of the vertical vibration of the vehicle, Kalman filter P3
The configuration of will be described.

First, a dynamic physical model of the vertical vibration of the vehicle is constructed. Focusing on any one of the four wheels of the vehicle and regarding the vertical vibration as one-degree-of-freedom vibration as shown in FIG. 4, its equation of motion can be expressed as the following equation (1).

m (−0) + C (−0) + K (x−x0) = 0 (1) where m: sprung mass applied to the wheel, x: sprung vertical absolute displacement, x0: road vertical vertical absolute displacement , C: shock absorber damping coefficient, K: coil spring spring constant.

Here, when variables (1) are transformed by variable conversion as in the following formulas (2) and (3), the following formula (4) is obtained.

x1 = x (2) x2 = (3) 2 =-(K / m) x1- (C / m) x2 + (C / m) 0+ (K / m) x0 (4) where 1 = It is X2.

Further, the observable damping force y can be described by the following equation (5).

y = C (x2-0) (5) Here, the road surface disturbance v which is the system disturbance is expressed by the following equation (6),
Observing the observation noise w of the damping force y as in the following equation (7),
By transforming equations (4) and (5), the following equations (8) and (9) are obtained.

v = (C / m) 0+ (K / m) x0 (6) w = -C0 (7) 2 =-(K / m) x1- (C / m) x2 + v (8) y = Cx2 + w ... (9) Therefore, the state equation and the output equation are given by the following equation (10),
It can be described as (11).

In this way, the dynamic physical model of this embodiment is expressed by the equation (10),
Obtained as in (11).

Where the irregular vector signal Is generated by equation (10), which is observed by equation (11). In this case, in equations (10) and (11), which are linear systems, the observable damping force y is used to generate an irregular vector signal. Estimate of Optimal estimate that minimizes the mean square of the estimation error with It is given by the following equation (12).

Where the gain matrix Is an estimation error when it is assumed that the system disturbance v and the observation noise w are white Gaussian noises that are independent of each other. The covariance matrix of If is defined as the following expression (13), it can be described as the following expression (14).

Here, the intensity W is described by the following equation (15).

^{Ε [w (t) w T} (τ)] = W (t) δ (t-τ) ...
(15) However, covariance matrix Satisfies the relationship shown in the following equation (16).

Here, the intensity V is described by the following equation (17).

^{Ε [v (t) v T} (τ)] = V (t) δ (t-τ) ...
(17) In this case, the gain matrix Is calculated by the following equation (18).

On the other hand, the following equation (19) is established between the system disturbance v and the observation noise w.
Assuming there is a correlation as shown in, the gain matrix It can be described as the following expression (20).

However, the covariance matrix Satisfies the relationship shown in the following equation (21).

In this case, the gain matrix Is calculated by the following equation (22).

In the present embodiment, the gain matrix when it is assumed that the system disturbance (road disturbance) v and the observed noise w have a correlation as shown in equation (19). To use. The construction of the dynamic physical model of the vertical vibration of the vehicle and the configuration of the Kalman filter P3 have been described above.

Next, the damping force control process will be described with reference to the flowcharts shown in FIGS. This damping force control processing is executed when the absorber control computer 6 is started.

First, at step 100, an initialization process is performed to clear registers inside the CPU 6a and set initial values of various variables such as the target damping coefficient C ^* . In the following step 110, a process of reading the damping force y is performed. Next, the routine proceeds to step 120, where the current damping coefficient C is initialized or the target damping coefficient C ^* calculated in the previous processing is set. In the following step 130, a process for calculating the sprung vertical relative velocity from the damping force y and the damping coefficient C as in the following equation (23) is performed.

−0 = y × 1 / C (23) The processing of this step 130 functions as the relative speed calculation unit P4.

Next, in step 140, the relative sprung vertical displacement is
From the sprung vertical direction relative speed, a process of calculating as in the following expression (24) is performed.

x−x0 = ∫ (−0) dt (24) The processing of this step 140 functions as the relative displacement calculator P5.

In the following step 150, it is determined whether or not the sprung relative velocity (−0) calculated in step 130 is positive, and if the determination is affirmative, the routine proceeds to step 152, while if the determination is negative, the routine proceeds to step 170, respectively. move on. In step 152, step 13
It is determined whether the sprung vertical relative speed (−0) calculated in 0 is equal to or higher than the sprung vertical relative speed threshold VREF, and if the affirmative judgment is made, the step 160 is carried out, while if the negative judgment is made, the step is carried out. Proceed to 162, respectively. The sprung vertical relative speed (−0) is the sprung vertical relative speed threshold VREF
When the above is done, in step 160, the ROM is previously
According to the map shown in FIG. 6 stored in 6b, the lowest damping coefficient CLP is calculated when the sprung vertical relative speed (−0) is equal to or higher than the sprung vertical relative speed threshold VREF, and this damping coefficient is calculated. Perform processing to set CLP to minimum damping coefficient CL. In addition, the sprung vertical relative speed (-
0) is equal to or greater than the sprung vertical relative velocity threshold VREF, the highest damping coefficient CH2P is calculated, and the damping coefficient CH2P is set to the maximum damping coefficient CH. Here, the damping coefficient CH2P is a straight line connecting the point corresponding to the sprung vertical relative velocity (−0) calculated in step 130 on the polygonal line indicated by the two-dot chain line in FIG. 6 and the origin of the figure. Is calculated by calculating the slope of.

On the other hand, in step 162 which is executed when the sprung vertical relative speed (−0) is less than the sprung vertical relative speed threshold VREF, the sprung is read according to the map shown in FIG. 6 stored in advance in the ROM 6b. Vertical relative velocity (-0)
Is the less than the sprung vertical relative velocity threshold VREF, the highest damping coefficient CH1P and the lowest damping coefficient CLP are calculated, and this damping coefficient CH1P is the maximum damping coefficient CH, while the damping coefficient CLP is the minimum damping coefficient CL. Then, after performing the setting processing, respectively, the process proceeds to step 200.

On the other hand, in step 170, which is executed when the sprung vertical relative speed (−0) is not positive, the sprung vertical relative speed (−0) calculated in step 130 is equal to or lower than the sprung vertical relative speed threshold −VREF. If it is affirmative, the process proceeds to step 180, and if it is negative, the process proceeds to step 190. In step 180, which is executed when the sprung vertical relative speed (−0) is equal to or lower than the sprung vertical relative speed threshold −VREF, the sprung vertical direction is determined according to the map shown in FIG. 6 stored in advance in the ROM 6b. The lowest damping coefficient CL2N is calculated when the directional relative speed (-0) is equal to or lower than the sprung vertical relative speed threshold -VREF, and the damping coefficient CL2N is set to the minimum damping coefficient CL. In addition, the sprung vertical relative speed (-0)
Is the sprung vertical direction relative velocity threshold-calculates the highest damping coefficient CH2N when it is less than or equal to VREF, and after performing the process of setting this damping coefficient CH2N to the maximum damping coefficient CH,
Proceed to 200. Here, the damping coefficients CL2N and CH2N are shown in FIG.
It can be obtained by calculating the slope of a straight line connecting the point on the broken line indicated by the dotted line corresponding to the sprung vertical relative velocity (-0) calculated in step 130 and the origin of the figure. On the other hand, in step 190, which is executed when the sprung vertical relative speed (−0) exceeds the sprung vertical relative speed threshold −VREF, the sprung is spun according to the map shown in FIG. 6 stored in advance in the ROM 6b. The highest damping coefficient CH1N and the lowest damping coefficient CL1N when the vertical relative speed (-0) exceeds the sprung vertical relative speed threshold -VREF are calculated, and this damping coefficient CH1N is set to the maximum damping coefficient CH, while After performing the process of setting the damping coefficient CL1N to the minimum damping coefficient CL,
Go to step 200. In step 200, it is determined whether or not the sprung vertical relative displacement (x−x0) calculated in step 140 is negative. If the determination is affirmative, the process proceeds to step 220. On the other hand, if the determination is negative, the process proceeds to step 210. , Each proceed. In step 210 which is executed when the sprung vertical relative displacement (x-x0) is not negative, the seventh stored in the ROM 6b in advance.
According to the map shown in the figure, the sprung vertical relative displacement (x-
x0) is a non-negative spring constant KN, and after performing the process of setting this spring constant KN to the spring constant K,
Continue to 242. On the other hand, sprung vertical relative displacement (x-x0)
In step 220 executed when is negative, it is determined whether the sprung vertical relative displacement (x-x0) calculated in step 140 is less than the sprung vertical relative displacement threshold LREF, and a positive determination is made. If so, the process proceeds to step 230. On the other hand, if the determination is negative, the process proceeds to step 240. The sprung vertical relative displacement (x-x0) is the sprung vertical relative displacement threshold LREF
In step 230, which is performed when
According to the map shown in FIG. 7 stored in 6b, the spring constant K2P is calculated when the sprung vertical relative displacement (x−x0) is less than the sprung vertical relative displacement threshold LREF, and this spring constant K2P is calculated. Is set to the spring constant K, the routine proceeds to step 242. Here, the spring constant K2P is the seventh
A point on the broken line indicated by the one-dot chain line in the figure, corresponding to the sprung vertical relative displacement (x-x0) calculated in step 140,
It is obtained by calculating the slope of the straight line connecting the origin of the figure.
On the other hand, in step 240, which is executed when the sprung vertical relative displacement (x−x0) is greater than or equal to the sprung vertical relative displacement threshold LREF, the spring is loaded in accordance with the map shown in FIG. After the process of setting the spring constant K1P when the upper and lower relative displacement (x−x0) is equal to or greater than the sprung vertical relative displacement threshold LREF and setting the spring constant K1P to the spring constant K, step 242 Proceed to. These steps 150 to 240 function as the constant calculation unit P6.
Each such process is performed by the shock absorbers 2b, 3b, 4b, 5b.
The damping coefficient C of is the relative speed in the vertical direction on the spring (-0)
Depending on, the spring constant K of the coil springs 2c, 3c, 4c, 5c
Is nonlinearly changed in the regions shown in the maps of FIGS. 6 and 7 in accordance with the sprung vertical relative velocity (x-x0), and this is performed to correct this.

In the following step 242, it is determined whether or not the damping coefficient C is set to the maximum damping coefficient CH at the time of the previous processing based on whether or not the maximum damping coefficient flag FCH is set to the value 1, and a positive determination is made. Proceeding to step 246, the damping coefficient C is updated to the maximum damping coefficient CH calculated in steps 160, 162, 180, 190 at the time of this processing, and then the processing proceeds to step 250.
On the other hand, if a negative decision is made, the operation proceeds to step 244. Step two
At 44, in the previous process, it is determined whether the damping coefficient C is set to the minimum damping coefficient CL based on whether the maximum damping coefficient flag FCL is set to the value 1, and if a positive determination is made, step 248 Proceed to step 16 when processing this time.
After updating the damping coefficient C to the maximum damping coefficient CH calculated in 0, 162, 180, 190, the process proceeds to step 250. On the other hand, if a negative determination is made, the process directly proceeds to step 250.

In the following step 250, step 120, steps 160, 162,
The coefficient matrix of the Kalman filter is calculated using the damping coefficient C and the spring constant K determined by the processing of 180, 190, or steps 210, 230, 240. The process of setting as in the following equations (25), (26), (27) is performed.

Next, the optimal estimate of the vertical sprung absolute velocity Is the coefficient matrix set in step 250 Is used to perform a calculation by the Kalman filter represented by the following equation (28).

However, the gain matrix The above equation (19) between the system disturbance v and the observation noise w
It is a value calculated assuming that there is a correlation as shown in.
Each processing of these steps 250 and 260 is performed by the Kalman filter P.
Functions as 3.

In the following step 270, the optimal estimated value of the sprung vertical absolute velocity calculated in step 260 And the relative speed on the sprung vertical direction calculated in step 130 (
It is determined whether or not the ratio with respect to (0) is positive, and if the determination is affirmative, the process proceeds to step 280, and if the determination is negative, the process proceeds to step 290.

Optimal estimate of vertical sprung absolute velocity In step 280, which is executed when it is determined that the above and the sprung vertical relative velocity (−0) are in phase, the target damping coefficient C ^* is set to the optimal sprung vertical absolute velocity based on the Karnop theory. Estimated value After the processing of calculating the following equation (29) from the ratio of the relative velocity of the sprung body in the vertical direction (-0) and the current damping coefficient C, the process proceeds to step 282.

In step 282, it is determined whether or not the absolute value of the target damping coefficient C ^* calculated in step 280 exceeds the absolute value of the maximum damping coefficient CH calculated in any of steps 160, 162, 180, 190, and if a negative determination is made, step 286 On the other hand, when the determination is affirmative, in step 284, after performing the guard processing of limiting the target damping coefficient C ^* to the maximum damping coefficient CH and the processing of setting the maximum damping coefficient flag FCH to the value 1, step 3
Proceed to 00. On the other hand, the absolute value of the target damping coefficient C ^* is the maximum damping coefficient CH calculated in any of steps 160, 162, 180, 190.
In step 286, which is executed when it is determined that the absolute value of the target damping coefficient C ^* is less than the absolute value of
It is determined whether or not it is less than the absolute value of the minimum damping coefficient CL calculated by any of 60, 162, 180, 190, and if a negative determination is made, the routine proceeds to step 288, where both the maximum damping coefficient flag FCH and the minimum damping coefficient flag FCL are set to the value 0. After performing the resetting process, the process proceeds to step 300. On the other hand, if an affirmative decision is made, in step 290, the guard process for limiting the target damping coefficient C ^* to the minimum damping coefficient CL and the maximum damping coefficient flag FCH are set to the value 1. After performing the process, proceed to step 300.

On the other hand, the optimum estimated value of the vertical sprung absolute velocity At step 290, which is executed when it is determined that the above and the sprung vertical direction relative velocity (−0) are in opposite phases, the Carnop theory which is established on the premise of the semi-active control is supplemented and the actual vehicle travels. In order to apply, the target damping coefficient C ^* is set to the minimum damping coefficient CL set in any one of the processing of steps 160, 162, 180 and 190, and the minimum damping coefficient flag FCL is set to the value 1, and then the step 300 is executed. Proceed to. In step 300, control for driving the absorber control actuators 2d, 3d, 4d, 5d is performed in order to realize the target damping coefficient C ^* calculated in the process of step 280 or limited by any of the processes of steps 284, 290. A process of calculating a signal is performed. Continued Step 310
Then, after performing the processing of outputting the control signal calculated in step 300 to the absorber control actuators 2d, 3d, 4d, 5d, the process returns to step 110. These steps 270 to 310 function as the controlled variable computing unit P7.
After that, the damping force control process is executed by repeating the above steps 110 to 310.

In the present embodiment, the damping force type shock absorbers 2, 3, 4, 5 are provided in the damping force changing means M1 and the damping force sensors 11, 12, 1
3, 14 correspond to the damping force detecting means M2, respectively. Further, in the absorber control computer 6 and the process executed by the absorber control computer 6, step (130) is the sprung relative velocity calculating means M3, and step (250 to 260) is the sprung absolute velocity estimating means M4.
The steps (270 to 310) each function as the control means M5.

As described above, according to the present embodiment, the damping coefficient C of the shock absorbers 2b, 3b, 4b, 5b is set to the damping force sensor 11, 12, 1.
Relative sprung velocity (3,14 detected from damping force y)
-0) and the absolute sprung velocity, which is the optimum estimated value calculated by the Kalman filter Since the target damping coefficient C ^* calculated according to the ratio with the above is controlled, the road surface disturbance v can be blocked and the sprung mass absolute value can be cut off by only providing one type of damping force sensor 11, 12, 13, 14. The displacement x can be suppressed to the minimum and the riding comfort can be improved.

In addition, a damping coefficient C that changes non-linearly according to the sprung relative speed (-0) and the sprung relative displacement (x-x0) of the vehicle,
The spring constant K is calculated from the sprung relative speed (−0) and the sprung relative displacement (x−x0) each time the damping force control processing is executed,
Kalman filter coefficient matrix To update the optimal estimate of absolute sprung velocity Is calculated. Therefore, the damping coefficient C is Since it is adjusted to the target damping coefficient C ^* determined from the above, the shock absorbers 2b, 3b, 4b, 5b and the coil springs 2c, 3 of the vehicle are adjusted.
It is possible to realize ideal damping force control that fully considers the characteristics of c, 4c, and 5c.

Further, since the damping force control is executed independently for the four wheels, it is possible to sufficiently cope with the interference between the four wheels.

Moreover, since the load distribution of the four wheels can be detected by the damping force sensors 11, 12, 13, and 14, for example, even if the vehicle speed sensor, the stop lamp switch, the throttle position sensor, the neutral start switch, etc. are not provided,
It is possible to implement control of sudden vehicle position change suppression such as anti-roll, anti-squat, and anti-shift squat.

In the present embodiment, a dynamic physical model is constructed from the equation of motion of the vertical vibration of the vehicle, and the Kalman filter coefficient matrix is constructed. Configured to determine. However, for example, a dynamic mathematical model is constructed by a method such as system identification, and the coefficient matrix of the Kalman filter is May be determined.

Further, in the present embodiment, the optimum estimated value of the sprung absolute velocity is calculated by the Kalman filter. It is configured to calculate. However, for example, a so-called optimum filter such as a Wiener filter or an observer, which is capable of calculating the least-squares estimated amount of the sprung mass absolute speed, may be applied.

Further, in the present embodiment, the optimal estimated value of the sprung vertical absolute velocity is And it is determined that the sprung vertical direction relative velocity (−0) is in phase, the target damping coefficient C ^* is set to the optimum estimated value of the sprung vertical direction absolute velocity based on the Karnop theory. It is configured to be calculated from the current damping coefficient C and the ratio of the sprung vertical relative speed (−0). However, for example, in this case, the target damping coefficient C ^{* is set} to the maximum damping coefficient CH
It is also possible to carry out control to switch to two stages or multiple stages by setting to.

It is also possible to omit the steps 150 to 240 of the damping force control processing and use predetermined constants as the minimum damping coefficient CL, the maximum damping coefficient, and the spring constant K.

[Advantages of the Invention] As described in detail above, the damping force control device of the present invention measures only the damping force and estimates the damping force from the damping force using the parameters determined based on the dynamic model of the vertical motion of the vehicle. The control is performed so as to achieve the optimum target damping force derived using the sprung relative velocity calculated from the upper absolute velocity and the damping force. Therefore, the damping force can be gradually changed to the optimum damping force that can suppress the vertical sprung displacement of the vehicle to the minimum, so the adverse effect of road surface disturbance input can be blocked by measuring only the damping force. It has an excellent effect that it can be dramatically improved.

Further, the optimum estimated value of the sprung mass absolute speed can be estimated extremely accurately only by providing one type of detection means for detecting the damping force, and the optimum damping force can be determined based on this optimum estimated value. Therefore, by adjusting the damping force to a target damping force determined from this optimum estimated value, an ideal configuration that matches one of the vehicle suspension states is provided with a simple configuration having one type of detection means capable of measuring the damping force. Damping force control can be realized.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram conceptually illustrating the content of the present invention, FIG. 2 is a system configuration diagram of an embodiment of the present invention, FIG. 3 is the same control system diagram, and FIG. 4 is the same control. Explanatory drawing showing the target model, FIGS. 5 (1) and 5 (2) are flowcharts showing the same control, and FIGS. 6 and 7 are graphs showing the map. M1 …… Damping force changing means, M2 …… Damping force detecting means, M3 ……
Sprung relative speed calculation means, M4 ... sprung absolute speed estimation means, M5 ... Control means 1 ... Shock absorber control device, 2, 3, 4, 5 ... Damping force variable shock absorber, 11, 12, 13,14 ... Damping force sensor, 6 ... Absorber control computer,
6a ... CPU

Claims (1)

[Claims] 1. A damping force change, which is interposed between a sprung portion and an unsprung portion of a wheel portion of a vehicle and changes a damping force acting between the sprung portion and the unsprung portion in accordance with a command from the outside. Means, damping force detecting means for detecting the damping force equivalent amount of the wheel portion, and sprung relative speed calculating means for calculating a relative speed with respect to the road surface on the spring in accordance with the damping force detected by the damping force detecting means. A sprung absolute velocity estimating means for estimating a sprung absolute velocity of the vehicle according to the damping force detected by the damping force detecting means, using a parameter determined based on a dynamic model of the vertical movement of the vehicle And a target damping force of the wheel portion of the vehicle is determined based on the sprung absolute speed estimated by the sprung absolute speed estimating means and the sprung relative speed calculated by the sprung relative speed calculating means. Reduce the damping force of the wheel to the target A damping force control device comprising: a control unit that outputs a command for changing to a damping force to the damping force changing unit.