JP5613727B2 - Suspension control device - Google Patents

Description

  The present invention relates to a vehicle suspension control apparatus including a damping force variable damper capable of adjusting a damping force according to an input signal.

  2. Description of the Related Art In recent years, various types of damping force variable type dampers that can variably control damping force stepwise or steplessly have been developed as dampers used in automobile suspensions. As a mechanism to change the damping force, in addition to a mechanical type that changes the area of the orifice provided in the piston by a rotary valve, a magnetic viscous fluid (Magneto-Rheological Fluid: hereinafter referred to as MRF) is used as the hydraulic oil. An MRF type in which the viscosity of the MRF is controlled by an installed magnetic fluid valve is known. In a vehicle equipped with such a variable damping force damper (hereinafter simply referred to as a damper), the damping force of the damper is variably controlled in accordance with the running state of the vehicle, thereby improving steering stability and ride comfort. Is possible.

  Skyhook control based on skyhook theory is known as one of the techniques for improving riding comfort. In skyhook control in which ride comfort control (vibration control) is performed, the target damping force is set so as to suppress the vertical movement on the spring, so it is necessary to detect the sprung speed. Further, as a characteristic of the damper, even if the area of the orifice and the viscosity of the MRF are constant, the damping force changes according to the stroke speed. It is also necessary to detect the relative displacement speed with the bottom.

  Conventionally, in suspension control devices that perform skyhook control, it has been necessary to mount a vertical G sensor and a stroke sensor for each wheel in order to detect the vertical speed and stroke speed on the spring. However, since the stroke sensor is attached in the wheel house or in the vicinity thereof, it is difficult to secure an arrangement space. Therefore, in order to solve this problem, the relative displacement speed between the sprung and unsprung mass is calculated from the fluctuation amount of the wheel speed without installing a stroke sensor, and the damping force of the damper is calculated based on the calculated relative displacement speed. A suspension control device has been proposed (see Patent Document 1).

JP-A-6-48139

  However, in the suspension device of Patent Document 1, when the wheel is displaced relative to the vehicle body in the vertical direction according to the suspension geometry, the wheel is also displaced relative to the vehicle body in the front-rear direction according to the caster angle. The relative displacement speed between the sprung and unsprung parts is calculated by utilizing the fact that the wheel speed fluctuates. Therefore, when there is no caster angle set for the suspension or when it is very small, the relative displacement speed cannot be calculated, or the calculation accuracy is lowered.

  The present invention has been devised to solve the problems included in the conventional technology, and the state quantity of the vehicle used for damping force control of the damper is controlled regardless of the caster angle set for the suspension. The first object is to provide a suspension control device that can calculate with high accuracy, and the second object is to calculate the state quantity of the vehicle with high accuracy even when the input offset to one side continues. And

In order to solve such a problem, according to one aspect of the present invention, suspension control of a vehicle (V) including a damping force variable damper (6) capable of adjusting a damping force according to an input signal (Vw). A device (20), a wheel speed sensor (9) for detecting a wheel speed (Vw) of each wheel (3), and a vehicle speed based on a wheel speed fluctuation (ΔVw) detected by the wheel speed sensor. The basic input amount calculation means (37) for calculating the input amount (u ₁ ), and the basic input amount and the damping force (u ₂ ) of the variable damping force damper are input to the vehicle model (38) representing the behavior of the vehicle. By doing so, state quantity calculation means (33) for calculating the state quantities (S ₂ , Ss) of the vehicle, and damper control means for controlling the damping force of the damping force variable damper based on the calculated state quantities ( 23, 25) and the vehicle model Hazuki least one and a position calculating means for calculating (43, 44) of the vehicle at least one of the sprung position and unsprung position of the sprung position of said vehicle (x ₂₎ and the unsprung position (x ₁₎ By providing feedback to the model, the sprung position and unsprung position of the vehicle model in the steady state are converged to initial values. Here, the basic input amount means an input amount received by the wheel from the outside such as the road surface regardless of the suspension geometry.

  According to this configuration, the basic input amount of the vehicle is calculated based on the detected wheel speed fluctuation, and this value is input to the vehicle model, so that the state quantity of the vehicle used for damping force control of the damping force variable damper is obtained. Can be calculated. Therefore, the state quantity of the vehicle can be calculated with high accuracy regardless of the caster angle of the suspension. In addition, when at least one of the calculated sprung position and unsprung position is fed back to the vehicle model and converged to the initial value, even when the input offset to one continues, the entire system is offset to reduce the damping force. It is possible to suppress the occurrence of an error in the state quantity used for control of the variable damper, and the vehicle state quantity can be calculated with high accuracy.

  As described above, according to the present invention, it is possible to provide a suspension control device capable of calculating the state quantity of the vehicle used for damping force control of the damper with high accuracy regardless of the caster angle set for the suspension. it can.

1 is a schematic configuration diagram of a vehicle to which a suspension control device according to a first embodiment is applied. Model diagram of suspension shown in Fig. 1 The block diagram which shows schematic structure of the suspension control apparatus shown in FIG. Block diagram of the state quantity estimation unit shown in FIG. Time chart showing the relationship between wheel speed and contact load in the unsprung load single wheel model shown in FIG. The graph which shows the correlation with the wheel speed fluctuation | variation in the unsprung load single wheel model shown in FIG. Block diagram of the unsprung load single wheel model calculation unit shown in FIG. Block diagram of the vehicle speed estimation unit shown in FIG. Main part control block diagram of the vehicle speed estimation unit shown in FIG. Block diagram of the steering correction amount calculation unit shown in FIG. (A) A time chart comparing the estimated value of the sprung speed with the single wheel model shown in FIG. 4 and the sensor value, and (B) a time chart comparing the estimated value of the stroke speed with the sensor value of the single wheel model shown in FIG. Block diagram of skyhook control calculation unit shown in FIG. Target current map used by the target current setting unit shown in FIG. Block diagram of the unsprung vibration suppression control calculation section shown in FIG. Frequency response diagram showing wheel speed versus unsprung acceleration Time chart showing unsprung acceleration and target current by peak hold / ramp down circuit shown in FIG. (A) Time chart of wheel speed fluctuation before and after low-pass filter processing when traveling on a flat road, (B) Time chart of wheel speed fluctuation before and after low-pass filter processing when traveling on a rough paved road Flow chart showing the procedure of damping force control by the suspension control device shown in FIG. The block diagram which shows schematic structure of the suspension control apparatus which concerns on 2nd Embodiment. FIG. 19 is a flowchart showing the procedure of damping force control by the suspension control device shown in FIG.

  Hereinafter, an embodiment in which the suspension control device 20 according to the present invention is applied to a four-wheeled vehicle will be described in detail with reference to the drawings. In the figure, for the four wheels 3 and the elements arranged with respect to them, that is, the damper 6 and the wheel speed Vw, etc., subscripts indicating front, rear, left and right are attached to the reference numerals, for example, wheels 3fl (front left), wheel 3fr (right front), wheel 3rl (left rear), and wheel 3rr (right rear) are described.

<< First Embodiment >>
≪Schematic configuration of car V≫
First, a schematic configuration of the automobile V according to the first embodiment will be described with reference to FIG. A vehicle body 1 of an automobile (vehicle) V has wheels 3 with tires 2 mounted on the front, rear, left and right thereof. These wheels 3 are each provided with a suspension arm 4, a spring 5, a variable damping force damper (hereinafter simply referred to as a damper). 6) and the like. The vehicle V includes an ECU (Electronic Control Unit) 8 used for various controls, a wheel speed sensor 9 that detects a wheel speed Vw of each wheel 3 installed for each wheel 3, and a lateral acceleration of the vehicle body 1. A lateral G sensor 10 that detects Gy, a yaw rate sensor 11 that detects the yaw rate γ of the vehicle body 1, a steering angle sensor 12 that detects the steering angle δf, and the like are installed at appropriate positions of the vehicle body 1.

  Although illustration is omitted, the vehicle V includes an ABS (Antilock Brake System) that prevents wheel lock during braking, a TCS (traction control system) that prevents wheel slipping during acceleration, or ABS and TCS. In addition, a brake device capable of VSA (Vehicle Stability Assist) control, which is known as a vehicle behavior stabilization control system having an automatic brake function for a yaw moment control during turning, a brake assist function, and the like, is mounted. These ABS, TCS and VSA determine the slip state when the detected value of the wheel speed sensor 9 deviates by a predetermined value or more from the wheel speed based on the estimated vehicle speed Vb, and optimal brake control according to the traveling state Alternatively, the vehicle behavior is stabilized by performing traction control control.

  In addition, a brake pressure sensor that detects the brake fluid pressure Pb of the brake device, a torque sensor that detects the drive torque Te, a gear position sensor that detects the gear position Pg of the transmission, and the like are set in place in the automobile V. Yes.

  The ECU 8 includes a microcomputer, a ROM, a RAM, a peripheral circuit, an input / output interface, various drivers, and the like, and a damper for each wheel 3 via a communication line (CAN 13 (Controller Area Network in this embodiment)). 6 and the sensors 9 to 12 and the like. The suspension control device 20 is configured by the ECU 8 and these sensors 9 to 12.

  Although the detailed illustration of the damper 6 of this embodiment is omitted, it is a monotube type (de carvone type) so that the piston rod can slide in the axial direction with respect to a cylindrical cylinder filled with MRF. The piston inserted and attached to the tip of the piston rod divides the inside of the cylinder into an upper oil chamber and a lower oil chamber, and is located inside the communication passage that connects the upper oil chamber and the lower oil chamber and inside this communication passage The MLV coil is of a known configuration provided on the piston.

In the damper 6, the lower end of the cylinder is connected to the upper surface of the suspension arm 4 that is a wheel side member, and the upper end of the piston rod is connected to a damper base (upper part of the wheel house) that is a vehicle body side member. 2 schematically, each damper 6 has a mass composed of an unsprung mass having a mass M ₁ (a movable part below the suspension spring including the wheel 3, knuckle, and suspension arm 4) and the vehicle body 1. The spring 5 having M ₂ is connected together with the spring 5.

  When a current is supplied from the ECU 8 to the MLV coil, a magnetic field is applied to the MRF flowing through the communication path, and the ferromagnetic fine particles form a chain cluster. As a result, the apparent viscosity (hereinafter simply referred to as viscosity) of the MRF passing through the communication path increases, and the damping force of the damper 6 increases.

≪ECU8≫
Next, a schematic configuration of the ECU 8 that controls the damper 6 among the components of the suspension control device 20 will be described with reference to FIG. The ECU 8 performs not only the control of the damper 6 but also the control of ABS, TCS, and VSA. However, the description of the vehicle behavior control unit that performs these controls is omitted here.

  The ECU 8 estimates the vehicle state quantity that estimates the state quantity of the automobile V from the input unit 21 connected to each of the sensors 9 to 12 and the vehicle behavior control unit described above via the CAN 13 and the detection signals of the sensors 9 to 12. From the various values calculated by the unit 22 and the vehicle state quantity estimation unit 22 and the detection signals of the sensors 9 to 12, various control targets of the dampers 6 are improved in order to improve the handling stability and riding comfort of the automobile V. Set by a control target current setting unit 23 for setting a current, a current fixing unit 24 for setting a current fixing signal Sfix to fix the drive current of the damper 6 according to a predetermined condition, and a control target current setting unit 23 The target current Atgt of each damper 6 is selected from the various control target currents generated, and the drive current to each damper 6 (MLV coil) is generated according to the current fixing signal Sfix to reduce the damper 6. And a damper control unit 25 for controlling the force is configured as a major component.

<Vehicle state quantity estimation unit 22>
The vehicle state quantity estimation unit 22 estimates the state quantity of the automobile V by utilizing the fact that the wheel speed fluctuation ΔVw has a fixed relationship with the ground load fluctuation of the wheel 3. Based on a state quantity calculation unit 31 that estimates various state quantities of the vehicle V for each wheel using a vehicle model, and a vehicle body speed Vb that is a wheel speed correction amount for the state quantity calculation unit 31 (inner wheel side vehicle body speed Vbi and outer wheel side). A vehicle body speed estimating unit 32 for calculating the vehicle body speed Vbo). The state quantity calculation unit 31 includes a one-wheel model calculation unit 33, a four-wheel model calculation unit 34, and a slip determination unit 50 (see FIG. 4) for the front, rear, left and right wheels. The vehicle body speed estimation unit 32 includes an acceleration / deceleration force calculation unit 51, a steering correction amount calculation unit 53 that calculates a correction amount by a steering operation, and the like. Below, each part of the vehicle state quantity estimation part 22 is demonstrated in detail, referring FIGS. 4-11.

<State quantity calculation unit 31>
As shown in FIG. 4, in the state quantity calculation unit 31, the input wheel speed Vw (signal) is input to the subtractor 35 as an addition value. An inner wheel side vehicle speed Vbi or an outer wheel side vehicle body speed Vbo, which will be described later, is input to the subtracter 35 as a subtraction value, and the inner wheel side vehicle body speed Vbi or the outer wheel side vehicle body speed Vbo is obtained from each wheel speed Vw by the subtracter 35. By subtracting, the wheel speed Vw is corrected. The subtractor 35 also functions as a wheel speed fluctuation calculating means for calculating the wheel speed fluctuation ΔVw based on the wheel speed Vw.

  As will be described later, the inner wheel side vehicle speed Vbi or the outer wheel side vehicle speed Vbo input to the subtractor 35 is a wheel speed fluctuation component caused by a difference in trajectory length caused by a change in the vehicle speed of the vehicle V or a turning radius difference between the inner and outer wheels. It is calculated for removal. That is, the subtractor 35 subtracts the inner wheel side vehicle speed Vbi or the outer wheel side vehicle speed Vbo calculated by the vehicle body speed estimation unit 32 from each wheel speed Vw before being input to the band pass filter 36, thereby It functions as a correction means for performing a correction process for removing the vehicle body speed Vb component caused by the operation by the wheel speed Vw.

  The wheel speed Vw output from the subtracter 35 is input to the gain circuit 37 via the band pass filter 36. The bandpass filter 36 has a bandpass characteristic that allows a frequency component of 0.5 to 5 Hz to pass therethrough. In the present embodiment, the CAN 13 is used as the communication line, and the wheel speed Vw signal is input at an update period of about 10 to 20 msec. Therefore, the bandpass filter 36 blocks the high frequency component and the frequency component of the sprung resonance band. It has a low-pass characteristic that allows a band lower than about 5 Hz to pass through so that (a signal in a frequency range corresponding to sprung vibration) can be reliably extracted. On the other hand, when the wheel speed Vw signal is input at a shorter update period, a bandpass filter 36 having a low-pass characteristic of a higher band such as 20 Hz is used so that the frequency component of the unsprung resonance band can be extracted. Also good.

  The band-pass filter 36 has a high-pass characteristic that allows a band higher than about 0.5 Hz to pass through in order to remove a DC component from the continuously input wheel speed Vw signal. As a result, the vehicle body speed Vb component (vehicle body speed component due to braking / driving force) caused by an operation by the driver or the like can be removed from the low-frequency signal of 5 Hz or less corresponding to the sprung vibration. That is, the bandpass filter 36 functions as a wheel speed fluctuation extracting unit that extracts the wheel speed fluctuation ΔVw based on the wheel speed Vw. Since the DC component can be removed from the wheel speed Vw signal by the bandpass filter 36, it is possible to adopt a configuration in which the subtractor 35 for subtracting the vehicle body speed Vb from the wheel speed Vw is not provided.

The gain circuit 37 converts the wheel speed fluctuation ΔVw of each wheel into the unsprung load u ₁ by using the fact that the wheel speed fluctuation ΔVw and the unsprung load u ₁ (ground load fluctuation) have a certain correlation. . Hereinafter, the relationship between the wheel speed variation ΔVw used by the gain circuit 37 and the unsprung load u ₁ will be described.

For example, when the automobile V is traveling straight on a flat road at a constant speed, the ground contact load of the wheel 3 is constant and the wheel speed Vw is also constant. Here, in the wheel 3, the ground contact portion is deformed according to the ground load (unsprung mass M ₁ + sprung mass M ₂ ), and the dynamic load radius Rd of the tire 2 is smaller than that in the no-load state. ing. However, for example, when the ground load fluctuation amount increases or decreases as shown in FIG. 5B due to road surface unevenness during traveling at a speed of about 80 km / h, the wheel speed is caused by the change in the dynamic load radius Rd of the tire 2. The fluctuation amount is also increased or decreased as shown in FIG. 5A corresponding to the ground load fluctuation amount. Here, the wheel speed Vw also fluctuates at about 1 Hz, just as the ground load fluctuates at about 1 Hz due to road surface bounce. The wheel speed Vw and the ground load are both detected values by the sensor.

The wheel speed fluctuation ΔVw when the detection signals of both sensors at this time are obtained by bandpass processing (here, passing through a bandpass filter of 0.5 to 2 Hz) is plotted on the horizontal axis, and the ground load fluctuation is plotted on the vertical axis. The obtained graph is shown in FIG. As shown in FIG. 6, the wheel speed fluctuation ΔVw is proportional to the ground load fluctuation, and can be expressed as the following equation.
u ₁ = kΔVw
However, k is a proportionality constant.

Therefore, the gain circuit 37 of FIG. 4 calculates the unsprung load u ₁ of each wheel by multiplying the wheel speed fluctuation ΔVw by a proportional constant k. That is, the gain circuit 37 functions as a basic input amount calculation unit that calculates the unsprung load u ₁ that is the basic input amount of the automobile V based on the wheel speed fluctuation ΔVw detected by the wheel speed sensor 9.

In this way, by performing correction for removing the vehicle body speed Vb component from the wheel speed Vw from the wheel speed Vw signal, the wheel speed fluctuation ΔVw can be accurately calculated without being affected by the fluctuation of the vehicle speed. Further, by passing the wheel speed Vw signal to the band pass filter 36 corresponding to the sprung vibration, it is possible to calculate the unsprung load u ₁ with high accuracy based on the wheel speed variation Delta] Vw. Since the bandpass filter 36 cuts the frequency range corresponding to the unsprung vibration, it is not necessary to increase the detection system of the wheel speed sensor 9 and the measurement cycle / communication speed more than necessary. Also improves.

(Single wheel model calculation unit 33)
The unsprung load u ₁ output from the gain circuit 37 is input to a single wheel model 38 included in the single wheel model calculation unit 33. The one-wheel model calculation unit 33 inputs the unsprung load u ₁ to the one-wheel model 38, and thereby the vehicle V of the vehicle V such as the sprung speed S ₂ and the stroke speed Ss of the suspension 7 used for the calculation in the skyhook control unit 90. Calculate and output state quantities. That is, the one-wheel model 38 serves as state quantity calculation means for calculating various state quantities of the automobile V by treating the wheel speed fluctuation ΔVw as an external force.

ここで、Ｍ_１：ばね下質量、Ｍ_２：ばね上質量、ｘ_１：ばね下の上下方向位置、ｘ_２：ばね上の上下方向位置、であり、ｄ^２ｘ_１／ｄｔ^２は、ばね下の上下方向加速度、ｄ^２ｘ_２／ｄｔ^２は、ばね上の上下方向加速度である。 Here, an example of the one-wheel model 38 will be described in detail. As described above, each wheel 3 of the automobile V can be expressed as shown in FIG. 2, and the following equation is obtained using the unsprung load u ₁ of the wheel 3 as an input u. It can be represented by (1). In the formulas and drawings of the present specification, the first order differential value (dx / dt) and the second order differential value (d ² x / dt ² ) are displayed as follows.

Here, M ₁ : unsprung mass, M ₂ : sprung mass, x ₁ : vertical position under the spring, x ₂ : vertical position over the spring, and d ² x ₁ / dt ² is the spring The lower vertical acceleration, d ² x ₂ / dt ^2, is the vertical acceleration on the spring.

Here, the unsprung mass M ₁ and sprung mass M ₂ are known. On the other hand, the input u, the other unsprung load u _1, although the damper 6 includes damping force u ₂ of the damper 6 from being a damping force variable, the damping force u ₂ of the damper 6 is the one wheel model 38 it can be determined based on the unsprung load u ₁ at. Therefore, if calculated on the basis of the spring under load u ₁ is the wheel speed Vw, the damping force u ₂ of the damper 6, which is calculated based on the unsprung load u ₁ and which as input u, the spring constant between the sprung and unsprung By using a system matrix that takes into account K (spring constant of the spring 5), unsprung mass M ₁ , and unsprung mass M ₂ , the unsprung and unsprung vertical accelerations d ² x ₁ / dt ² , d ² x ₂ / dt ² , unsprung position x ₁ , unsprung speed dx / dt, and the like can be obtained. Incidentally, the stroke speed Ss _is represented by _{dx 2 / dt-dx 1 /} dt.

ただし、ｕ_１：ばね下荷重、ｕ_２：ダンパ６の減衰力、Ｋ：ばね定数、である。 Specifically, M ₁ · d ² x ₁ / dt ² and M ₂ · d ² x ₂ / dt ² in the above equation (1) are expressed as the following equations (2) and (3), respectively. Can do.

However, _{u 1:} under spring load, _{u 2:} damping force of the damper 6, K: a spring constant.

ただし、ｘ：状態変数ベクトル、Ａ，Ｂ：システム行列、である。
上式（２）〜（５）から、上式（４）は下式（６）として表される。

Therefore, in the single wheel model 38, the state equation of the following equation (4) is used as a model, and the state variable x of the following equation (5) is calculated from the input vector u.

Where x: state variable vector, A, B: system matrix.
From the above formulas (2) to (5), the above formula (4) is expressed as the following formula (6).

As shown in FIG. 7, the one-wheel model 38 using such a state equation inputs an input u to a calculator 39 using a system matrix B, and integrates an output from the calculator 39 via an adder 40. The output from the integrator 41 is input to the calculator 42 using the system matrix A and returned to the adder 40. By obtaining outputs of the first to fourth observation matrices 43 to 46 from the _single wheel model 38, the unsprung position x ₁ , the sprung position x ₂ , the sprung speed S ₂ (d ² x ₂ / dt ² ), and The stroke speed Ss (d ² x ₂ / dt ² −d ² x ₁ / dt ² ) can be calculated. The first observation matrix 43 is an unsprung position observation matrix and is [1 0 0 0]. The second observation matrix 44 is a sprung position observation matrix and is [0 1 0 0]. The third observation matrix 45 is a sprung speed observation matrix and is [0 0 0 1]. The fourth observation matrix 46 is a stroke speed observation matrix and is [0 0 −1 1]. That is, the first to fourth observation matrices 43 to 46 in the single-wheel model 38 are each based on the wheel speed fluctuation ΔVw and the unsprung position x ₁ , the sprung position x ₂ , the sprung speed S ₂ and the stroke speed Ss. Is a means for calculating.

In this way, by inputting the unsprung load u ₁ calculated based on the wheel speed Vw to the one-wheel model 38, the sprung speed S ₂ and the stroke are determined regardless of whether or not the caster angle is set for the suspension 7. The speed Ss can be calculated. Since the sprung speed S ₂ and the stroke speed Ss can be calculated from the unsprung load u _1, it is not necessary to provide the vertical G sensor and the stroke sensor in the automobile V, and the cost of the suspension control device 20 can be reduced.

Returning again to FIG. 4, one wheel model calculation unit 33 includes a PID circuit 47 as a feedback means for feeding back the unsprung position x ₁ and the sprung position x ₂ calculated by the one-wheel model 38. As a result, the one-wheel model calculation unit 33 calculates the unsprung position x ₁ and the sprung position x ₂ calculated by the one-wheel model 38 and the unsprung reference position x ₁ o (= 0) or the sprung reference position x ₂ o ( = 0) based on a deviation between are corrected unsprung position x ₁ and the sprung position x ₂ is calculated in one-wheel model calculation unit 33, the one wheel model 38 in the steady state such as constant-speed straight running flat road sprung position x ₂ and unsprung position x ₁ is made to converge to the reference position (initial value).

As a result, the unsprung load u ₁ is adjusted with reference to the reference position, and therefore, even when the input offset to one side continues, the entire system is offset to cause an error in the sprung speed S ₂ and the stroke speed Ss. Is suppressed from occurring. In addition, data can be used on other control systems.

As described above, the one-wheel model calculation unit 33 receives the unsprung load u ₁ and the damping force u ₂ of the damper 6 as inputs, and obtains the outputs of the first observation matrix 43 and the second observation matrix 44 from the single-wheel model 38. It functions as position calculation means for calculating the lower position x ₁ and the sprung position x ₂ . Incidentally, the one wheel model calculation unit 33 here, although a form to feed back both the PID circuit 47 spring under the position x ₁ and the sprung position x _2, at least the unsprung position x ₁ and the sprung position x ₂ one was the feedback may be in the form to correct the unsprung position x ₁ and the sprung position x _2. Sprung velocity S ₂ and the stroke speed Ss calculated in one-wheel model calculation unit 33, as shown in FIG. 3, is input to the skyhook control unit 90.

(Four wheel model calculation unit 34)
As shown in FIG. 4, the four-wheel model calculation unit 34 included in the state quantity calculation unit 31 includes a pitch angular velocity calculation unit 48 and a roll angular velocity calculation unit 49. The unsprung load u ₁ output from the gain circuit 37 is input to the pitch angular velocity calculation unit 48. The pitch angular velocity calculation unit 48 calculates the acceleration / deceleration (longitudinal acceleration Gx) of the vehicle V based on the input unsprung load u ₁ of each wheel (based on the wheel speed Vw), and calculates the calculated acceleration / deceleration and suspension. characteristics, determine the pitch angular velocity ωp based on such sprung mass M _2. On the other hand, the lateral acceleration Gy detected by the lateral G sensor 10 is input to the roll angular velocity calculation unit 49. Roll angular velocity calculating unit 49, and the lateral acceleration Gy inputted, the suspension characteristics, obtaining the roll angular velocity ωr based on such sprung mass M _2. As shown in FIG. 3, the pitch angular velocity ωp is input to the pitch control unit 91, and the roll angular velocity ωr is input to the roll control unit 92.

(Slip determination unit 50)
The slip determination unit 50 receives the wheel speed Vw output from the subtractor 35, that is, the deviation between the wheel speed Vw of each wheel and the estimated vehicle body speed Vb. The slip determination unit 50 determines whether or not the absolute value of the input wheel speed Vw (deviation) is greater than or equal to a predetermined value, that is, the wheel speed Vw detected by the wheel speed sensor 9 deviates from the vehicle body speed Vb by a predetermined value or more. If it is equal to or greater than a predetermined value, it is determined that the corresponding wheel 3 is in a slip state, and a slip signal SS is output. The output slip signal SS is input to a vehicle behavior control unit (not shown) that controls the ABS, TCS, and VSA. Note that when the slip signal SS is input and the ABS, TCS, or VSA is operated, the vehicle behavior control unit causes the input unit 21 to input an operation signal indicating these operations.

<Car body speed estimation unit 32>
As shown in FIG. 8, the vehicle speed estimation unit 32 in FIG. 3 includes an acceleration / deceleration force calculation unit 51 that calculates an acceleration / deceleration force F (Fe, Fs, Fd) of the vehicle V, and an acceleration / deceleration force calculation unit 51. A vehicle body speed calculation unit 52 that calculates the vehicle body speed Vb based on the speed, a steering correction amount calculation unit 53 that calculates a correction amount (an inner wheel vehicle body speed ratio Rvi and an outer wheel vehicle body speed ratio Rvo described later) by a steering operation, and a steering correction A vehicle body speed correction unit 54 that corrects the vehicle body speed Vb based on the correction amount calculated by the amount calculation unit 53 is provided.

  The acceleration / deceleration force calculation unit 51 includes an acceleration force calculation unit 55 that calculates a driving force Fe (acceleration force) of the vehicle V based on the output of a prime mover such as an engine or a motor, and a road surface gradient that calculates a deceleration force Fs of the vehicle V based on a road surface gradient. A deceleration force calculation unit 56 and a deceleration force calculation unit 57 that calculates the deceleration force Fd of the automobile V caused by factors other than the road surface gradient are included.

  The acceleration force calculation unit 55 receives the driving torque Te detected by the torque sensor and the gear position Pg as input, and calculates the driving force Fe of the vehicle V based on the prime mover output.

  The road surface gradient deceleration force calculation unit 56 detects, for example, the detection detected by the front and rear G sensors from the acceleration / deceleration force obtained by subtracting the deceleration force Fd calculated by the deceleration force calculation unit 57 from the driving force Fe calculated by the acceleration force calculation unit 55. By reducing the acceleration / deceleration force obtained by multiplying the longitudinal acceleration Gxd by the vehicle body weight M, the deceleration force Fs due to the road surface gradient is calculated.

  The deceleration force calculation unit 57 receives the brake fluid pressure Pb of the brake device as an input, a brake deceleration force calculation unit 58 that calculates the deceleration force of the automobile V applied to a brake operation that increases in proportion to the brake fluid pressure Pb, and a wheel speed. By using the average value of Vw as the approximate vehicle speed, a travel resistance calculation unit 59 that calculates a deceleration force applied to the travel resistance caused by the vehicle body shape and the approximate vehicle speed, and a feedback resistor that calculates a travel resistance force by wheel speed feedback A force calculating unit 60, and adding the calculation results of the brake deceleration force calculating unit 58, the running resistance calculating unit 59, and the feedback resistance force calculating unit 60 to reduce the deceleration force of the vehicle V caused by factors other than the road surface gradient. Fd is calculated.

  The vehicle body speed calculation unit 52 subtracts the deceleration force Fs calculated by the road surface gradient deceleration force calculation unit 56 from the driving force Fe calculated by the acceleration force calculation unit 55 and the deceleration force calculated by the deceleration force calculation unit 57. After the acceleration / deceleration force F of the vehicle body 1 is calculated by subtracting Fd, the acceleration / deceleration force F is divided by the vehicle body weight M to obtain an acceleration, and the vehicle speed Vb is calculated by integrating the acceleration. The calculated vehicle body speed Vb is input to the vehicle body speed correction unit 54.

Here, with reference to FIG. 9, the process in the acceleration force calculation part 55 and the deceleration force calculation part 57 is demonstrated in detail. The driving torque Te is input to the multiplier 61. The gear position Pg is input to the gear position / transmission gear ratio conversion circuit 62. The gear position-transmission gear ratio conversion circuit 62 obtains the transmission gear ratio Rg by referring to the table based on the gear position Pg and inputs the output transmission gear ratio Rg to the multiplier 61. Note that the multiplier 61 is also input the first wheel speed gain G ₁ of the first wheel speed gain setting circuit 63 to be described later.

First wheel speed gain G _1, in the first wheel speed gain setting circuit 63, that each wheel speed sensor 9 on the basis of the average wheel speed Vwav a wheel speed average value of the wheel 3 detected, referring to the reference table Is set by The first wheel speed gain G ₁ in this example is the average wheel speed Vwav of minute regions 0, the average wheel speed Vwav is substantially constant is larger than a predetermined threshold value. At the multiplier 61, the drive torque Te, the transmission gear ratio Rg and the first wheel speed gain G ₁ is multiplied is in wheel torque Tw which is the output of the driving wheels is calculated, the wheel torque Tw is torque - drive It is input to the force conversion circuit 64 and is divided by the dynamic load radius Rd of the tire 2 to be converted into the driving force Fe of the automobile V, and the output is input to the subtractor 66 through the gain circuit 65 as an added value. .

  In addition to the driving force Fe output from the gain circuit 65, the subtractor 66 receives a braking force Fb, a running resistance force Fr, and a feedback resistance force Ffb described later.

The brake fluid pressure Pb is input to the multiplier 67. The multiplier 67 also receives the second wheel speed gain G ₂ from the second wheel speed gain setting circuit 68. Second wheel speed gain G ₂ is, in the second wheel speed gain setting circuit 68, is set by referring to the reference table based on the average wheel speed Vwav. Note that the second wheel speed gain G ₂ is in this example, the average wheel speed Vwav of minute regions 0, the average wheel speed Vwav is substantially constant is larger than a predetermined threshold value. The braking force Fb is calculated from the multiplier 67 by being multiplied by the brake fluid pressure Pb and the second wheel speed gain G ₂ corresponds to the braking force by the brake device, the braking force Fb indicating a positive value, The value is input to the subtracter 66 as a subtraction value.

  The average wheel speed Vwav is input to the running resistance setting circuit 69. The running resistance force setting circuit 69 sets the running resistance force Fr depending on the vehicle speed (average wheel speed Vwav) by referring to the reference table based on the input average wheel speed Vwav. The traveling resistance force Fr indicating a positive value calculated by the traveling resistance setting circuit 69 is input to the subtractor 66 as a subtraction value.

  Further, the average rear wheel speed Vwavr, which is the average wheel speed of the rear wheel 3 r that is the driven wheel, is input to the feedback resistance calculating unit 60. The feedback resistance force calculation unit 60 sets a running resistance force based on a proportional gain based on a deviation ΔV obtained by subtracting the average rear wheel speed Vwavr from the vehicle body speed Vb input to the subtractor 71, and An integration circuit 73 that sets the running resistance force based on the integral gain and a differentiation circuit 74 that sets the running resistance force based on the differential gain are provided. The outputs of the proportional circuit 72, the integrating circuit 73, and the differentiating circuit 74 are input to the adder 75 and added to output a feedback resistance force Ffb that is a correction value by feedback of the vehicle body speed Vb. The output feedback resistance force Ffb is input to the subtractor 66 as a subtraction value.

  The subtractor 66 subtracts the braking force Fb, the traveling resistance force Fr, and the feedback resistance force Ffb from the driving force Fe, the deceleration force Fs due to the road gradient in FIG. 8 (not shown), and the output acceleration / deceleration force F is obtained. The acceleration / deceleration force-acceleration / deceleration conversion circuit 76 inputs the acceleration / deceleration force F by the vehicle body weight M to convert it into the acceleration / deceleration (longitudinal acceleration Gx) of the automobile V. The acceleration / deceleration of the automobile V is input to the accumulator 78 via the gain circuit 77 and accumulated, and is output as the vehicle body speed Vb.

  Thus, the vehicle speed Vb for correcting the wheel speed Vw is obtained by calculating the vehicle speed Vb of the vehicle V based on the driving force Fe, the braking force Fb, the travel resistance force Fr, and the feedback resistance force Ffb. Can do.

  Returning to FIG. 8, the steering correction amount calculation unit 53 includes a turning radius calculation unit 79 that calculates the turning radius TR of the vehicle V based on each wheel speed Vw and the yaw rate γ, and the tread T of the vehicle V and the calculated turning radius. Based on TR, a turning state amount as a correction amount, that is, an inner ring vehicle body speed ratio Rvi and an outer ring vehicle body speed ratio Rvo, which are ratios to the vehicle body speed Vb of each vehicle body part corresponding to the inner wheel and the outer wheel, are calculated. A ratio calculation unit 80.

  The processing in the steering correction amount calculation unit 53 will be described in detail with reference to FIG. The average wheel speed Vwav of the wheel speed Vw detected by each wheel speed sensor 9 is input to the divider 81 as a dividend (numerator). The divider 81 also receives the yaw rate γ detected by the yaw rate sensor 11 as a divisor (denominator). The divider 81 divides the average wheel speed Vwav of each wheel by the yaw rate γ, thereby dividing the vehicle V. A turning radius TR is calculated. When the yaw rate γ becomes 0 during division, the value is regulated by a known method such as replacement with a constant. The calculated turning radius TR is input to the subtracter 83 and the adder 85 as an added value. The subtractor 83 and the adder 85 respectively calculate the inner ring turning radius TRi and the outer ring turning radius TRo by subtracting or adding 1/2 of the tread T stored in the memory 82 to the inputted turning radius TR. . Outputs from the subtracter 83 and the adder 85 are input to the dividers 84 and 86 as dividends, respectively. The dividers 84 and 86 receive the turning radius TR of the vehicle V calculated by the divider 81 as a divisor, and each divider 84 and 86 turns the turning radius TRi or the outer wheel turning radius TRo of the turning of the vehicle V. By dividing by the radius TR, the inner wheel body speed ratio Rvi and the outer wheel body speed ratio Rvo are calculated.

  The inner ring vehicle body speed ratio Rvi and the outer wheel vehicle body speed ratio Rvo calculated by the respective dividers 84 and 86 are input to the vehicle body speed correction unit 54 as shown in FIG. By multiplying the inner ring vehicle body speed ratio Rvi and the outer ring vehicle body speed ratio Rvo, respectively, the inner wheel side vehicle body speed Vbi, which is the vehicle body speed Vb of the vehicle body part corresponding to the inner ring, and the outer wheel, which is the vehicle body speed Vb of the vehicle body part corresponding to the outer wheel. A side vehicle body speed Vbo is calculated. That is, the vehicle body speed correction unit 54 is a correction unit that corrects the vehicle body speed Vb based on the inner ring vehicle body speed ratio Rvi and the outer ring vehicle body speed ratio Rvo.

  In this way, by correcting the vehicle body speed Vb according to the turning state of the vehicle V, the vehicle speed Vb (Vbi · Vbo) on the inner wheel side and the outer wheel side that changes according to the steering operation of the driver is accurately calculated. Is done.

  The inner wheel side vehicle speed Vbi and the outer wheel side vehicle speed Vbo are input as subtraction values to the state quantity calculation unit 31 as shown in FIG. 4, more specifically, to the subtractor 35 provided on the upstream side of the band pass filter 36, It is used for calculation of wheel speed fluctuation ΔVw based on the wheel speed Vw, and for removal of wheel speed fluctuation components due to the difference in trajectory length caused by the vehicle V speed fluctuation component and the turning radius difference between the inner and outer wheels. .

As described above, the inner wheel side vehicle speed Vbi or the outer wheel side vehicle body speed Vbo is subtracted from each wheel speed Vw input in the state quantity calculation unit 31, thereby eliminating the influence of the braking / driving force of the vehicle V from the wheel speed Vw. because the state quantity of the motor vehicle V (sprung speed S ₂ and the stroke speed Ss) is calculated with higher accuracy. Further, the vehicle body speed correction unit 54 corrects the vehicle body speed Vb based on the inner wheel vehicle body speed ratio Rvi and the outer wheel vehicle body speed ratio Rvo, so that the vehicle body speed Vb corresponding to each wheel is calculated with high accuracy. Since the influence on the wheel speed Vw due to the turning of the vehicle V is eliminated, the state quantity of the automobile V is calculated with higher accuracy.

11 (A) is a time chart showing the sprung speed detected by using a sensor, and a state quantity calculation unit 31 sprung speed S ₂ calculated by by broken lines and respectively solid line, FIG. 11 (B ) Is a time chart in which the stroke speed detected using the sensor and the stroke speed Ss calculated by the state quantity calculation unit 31 are indicated by a broken line and a solid line, respectively. As shown in FIG. 11, the stroke speed Ss and sprung speed S ₂ calculated, the sensor value substantially to have matched, the state quantity calculation unit 31 the stroke speed based on the wheel speed Vw Ss and sprung speed S ₂ can be calculated with high accuracy. Further, in the present embodiment calculates the unsprung load u _1, based on the wheel speed Vw, to the unsprung load u ₁ to the input of the vehicle model, whether or caster angle to a suspension 7 is set not, it is possible to calculate the sprung speed S ₂ and the stroke speed Ss.

<Control target current setting unit 23>
As shown in FIG. 3, the control target current setting unit 23 performs skyhook control, performs a skyhook control unit 90 that sets the skyhook control target current Ash, and performs pitch control based on the pitch angular velocity ωp, thereby performing a pitch control target. Pitch control unit 91 for setting current Ap, roll control based on roll angular velocity ωr, roll control unit 92 for setting roll control target current Ar, roll control based on steering steering angle δf, and steering angle proportional control target current The steering angle proportional control unit 93 for setting Asa, the unsprung vibration control of the automobile V, the unsprung vibration control unit 95 for setting the unsprung vibration control target current Au, and the minimum damping force depending on the vehicle speed. A minimum target current control unit 96 for setting a minimum target current Amin for generation is provided.

  The skyhook control unit 90 performs ride comfort control (vibration suppression control) that suppresses vehicle shake when overcoming road surface irregularities and enhances ride comfort. The pitch control unit 91 performs body posture control that optimizes the posture of the vehicle body 1 by suppressing pitching during rapid acceleration or sudden deceleration of the vehicle V. A roll posture control unit 94 including a roll control unit 92 and a steering angle proportional control unit 93 performs vehicle body posture control that suppresses rolling during turning of the vehicle V and optimizes the posture of the vehicle body 1. The unsprung vibration suppression control unit 95 suppresses vibrations in the unsprung resonance region and improves the grounding property and riding comfort of the wheel 3.

<Skyhook control unit 90>
Next, processing in the skyhook control unit 90 will be described in detail with reference to FIGS. 12 and 13. In the skyhook control unit 90, the sprung speed S ₂ calculated by the state quantity calculation unit 31 in FIG. 3 is input to the damping force base value calculation unit 97. Damping force base value calculation section 97, based on the sprung speed S ₂ inputted, the spring - calculating a damping force base value Dsb by referring to damping force map. The calculated damping force base value Dsb is input to the gain circuit 98. In the gain circuit 98, the skyhook target damping force Dsht is calculated by multiplying the damping force base value Dsb by the skyhook gain Gsh, and the calculated target damping force Dsht is input to the target current setting circuit 99. The target current setting circuit 99 also receives a stroke speed Ss. The target current setting circuit 99 refers to the current map shown in FIG. 13 based on the skyhook target damping force Dsht and the stroke speed Ss. The skyhook control target current Ash for the damper 6 is set, and the skyhook control target current Ash is output.

<Unsprung vibration suppression control unit 95>
Next, the unsprung vibration suppression control unit 95 of FIG. 3 will be described in detail with reference to FIGS. As shown in FIG. 14, in the unsprung vibration suppression control unit 95, the input wheel speeds Vw are input to the bandpass filter 101. The band-pass filter 101 has a band-pass characteristic of 8 to 18 Hz in order to pass the wheel speed Vw signal in the unsprung resonance region. Therefore, the band pass filter 101 extracts a signal in a frequency range higher than the frequency range of 0.5 to 5 Hz of the band pass filter 36 (FIG. 4) for skyhook control. The cut frequency on the high frequency side of the band pass filter 36 for skyhook control is 5 Hz, the cut frequency on the low frequency side of the band pass filter 101 for unsprung vibration suppression control is 8 Hz, and both bandpass Since the band gap is provided between the filters 36 and 101, mutual interference due to skyhook control and unsprung vibration suppression control is prevented.

  The wheel speed Vw signal input from the CAN 13 includes signals other than the unsprung resonance region. For example, the wheel speed Vw signal having a frequency characteristic shown in FIG. The wheel speed Vw signal in the unsprung resonance region as shown in FIG. 15B is included. Therefore, by passing the wheel speed Vw signal through the bandpass filter 101 corresponding to the unsprung resonance region, the wheel speed Vw signal including the unsprung signal component is extracted, and the DC component is removed from the wheel speed Vw signal. be able to. That is, the bandpass filter 101 functions as a wheel speed fluctuation extracting unit that extracts the wheel speed fluctuation ΔVw based on the wheel speed Vw signal.

The wheel speed fluctuation ΔVw that has passed through the bandpass filter 101 is input to the absolute value calculation circuit 102 and converted into an absolute value of the wheel speed fluctuation ΔVw. Wheel speed variation ΔVw is proportional to the unsprung load u ₁ as described above, the vertical acceleration of the unsprung which is obtained by dividing the unsprung load u ₁ in unsprung mass M ₁ also corresponds to the wheel speed variation ΔVw value It becomes. Therefore, unsprung vibration can be suppressed by generating a damping force corresponding to the absolute value of the vertical acceleration.

The wheel speed fluctuation ΔVw output from the absolute value calculation circuit 102 is input to the gain circuit 103 and multiplied by the gain, whereby the magnitude (absolute value) of the unsprung acceleration Gz ₁ that is the basic input amount of the automobile V is obtained. Calculated. Specifically, the gain circuit 103 multiplies the wheel speed variation ΔVw a value proportional constant k described in connection divided by the unsprung mass M ₁ in FIG. 6 as the gain.

The unsprung acceleration Gz ₁ output from the gain circuit 103 is input to the target current setting circuit 104. The target current setting circuit 104, calculates current is calculated corresponding to the unsprung acceleration Gz _1, unsprung vibration suppression control target current Au by the peak hold ramp down control based on the calculated current is set.

The target current setting circuit 104 responds to the input of the unsprung acceleration Gz _{1 having} the characteristics shown in FIG. 16A based on the calculated current indicated by the broken line in FIG. 16B and the solid line in FIG. The unsprung vibration suppression control target current Au as shown is set. Specifically, the target current setting circuit 104 holds the maximum value of the input calculated current as the unsprung vibration suppression control target current Au for a predetermined time, and after the predetermined time has elapsed since the input of the maximum value. Then, the value of the unsprung vibration suppression control target current Au is decreased with a predetermined gradient. That is, when the unsprung acceleration Gz ₁ is increased in accordance with the unsprung acceleration Gz ₁ (fast) while setting the value of the unsprung vibration suppression control target current Au to respond, the unsprung acceleration Gz ₁ In the case of reduction, the response is set slower than in the case of increase. As a result, the unsprung vibration is attenuated more effectively and stably than when the calculated current as shown by the broken line is set to the unsprung vibration suppression control target current Au.

  Returning to FIG. 14, the unsprung vibration suppression control target current Au output from the target current setting circuit 104 is input to the limiting circuit 105. The limit circuit 105 limits the upper limit of the unsprung vibration suppression control target current Au to the upper limit value Aumax and outputs the unsprung vibration suppression control target current Au. That is, the limit circuit 105 sets the upper limit value Aumax to the unsprung vibration suppression control target current Au when the input unsprung vibration suppression control target current Au exceeds the upper limit value Aumax. Thereby, the unsprung vibration suppression control target current Au set according to the magnitude of the wheel speed fluctuation ΔVw exceeds the upper limit value Aumax set in consideration of the power supply capacity of the vehicle V and the damping force characteristics of the damper 6. Setting is prevented.

  The wheel speed fluctuation ΔVw output from the absolute value calculation circuit 102 is input not only to the gain circuit 103 but also to the low-pass filter 106. Here, the low-pass filter 106 has a low-pass characteristic that allows a band lower than 1 Hz to pass. Upper limit setting circuit 107 sets upper limit value Aumax in accordance with the absolute value of wheel speed fluctuation ΔVw that has passed through low-pass filter 106, and causes upper limit value Aumax to be input to limit circuit 105. Specifically, the upper limit setting circuit 107 sets the upper limit value Aumax so that when the absolute value of the wheel speed fluctuation ΔVw exceeds a predetermined value, the wheel speed fluctuation ΔVw increases as the wheel speed fluctuation ΔVw increases.

  The limit circuit 105 changes the upper limit of the unsprung vibration suppression control target current Au according to the input upper limit value Aumax, that is, the upper limit value Aumax decreases as the absolute value of the wheel speed fluctuation ΔVw that has passed through the low-pass filter 106 increases. Change as follows. The effect will be described below.

  On a relatively flat pavement, the wheel speed fluctuation ΔVw (absolute value) after passing through the low-pass filter 106 indicated by a solid line in FIG. 17A is smaller than the wheel speed fluctuation ΔVw before passing through the low-pass filter 106 indicated by a thin line. And the average value is also small. On the other hand, in rough pavement, as shown in FIG. 17B, not only the wheel speed fluctuation ΔVw before passing through the low-pass filter 106 shown by the thin line is larger than the flat road of (A), but also by the solid line. The wheel speed fluctuation ΔVw after passing through the low-pass filter 106 shown in FIG. Therefore, when the absolute value of the wheel speed fluctuation ΔVw that has passed through the low-pass filter 106 is large, it is assumed that the road surface is rough, and the limiting circuit 105 reduces the unsprung vibration suppression control target current Au (unsprung vibration suppression control). Can be prevented from being deteriorated by setting the lower vibration suppression control target current Au to be excessively high.

  Thus, the unsprung vibration suppression control unit 95 can be configured to set the unsprung vibration suppression control target current Au based on the wheel speed Vw signal. Since the determination is based on the magnitude of the wheel speed variation ΔVw of the unsprung resonance region component of Vw, the unsprung vibration suppression control can be performed without intervening other factors such as the sprung.

<Current fixing unit 24>
Returning to FIG. 3, when any of the operation signals indicating that VSA, ABS, and TCS are operating is input to the input unit 21, the current fixing unit 24 has an unstable behavior of the vehicle V. As a thing, the electric current fixed signal Sfix is output. The output current fixing signal Sfix is input to the damper control unit 25.

<Damper control unit 25>
The damper control unit 25 includes a high current selection unit 108 and a current control unit 109. The high current selection unit 108 sets the set skyhook control target current Ash, pitch control target current Ap, roll control target current Ar, steering angle proportional control target current Asa, unsprung vibration suppression control target current Au, and minimum target current Amin. The largest value is set as the target current Atgt.

  A target current Atgt and a current fixing signal Sfix are input to the current control unit 109. When the current fixing signal Sfix is not input, the current control unit 109 generates a drive current to each damper 6 based on the target current Atgt set by the high current selection unit 108 and controls the damping force of the damper 6. . On the other hand, when the current fixing signal Sfix is input, the current control unit 109 fixes the current based on the target current Atgt immediately before the current fixing signal Sfix is input in order to avoid a sudden change in the damping force of the damper 6. (That is, the damping coefficient of the damper 6 is fixed to a predetermined value), a driving current to each damper 6 is generated based on the fixed target current Atgt, and the damping force of the damper 6 is controlled.

  Here, the current control unit 109 maintains the target current Atgt constant over a period during which the current fixing signal Sfix is input. Alternatively, the target current Atgt may be maintained constant until a predetermined time elapses after the input of the current fixing signal Sfix is lost.

≪Damping force control procedure≫
The ECU 8 configured in this way performs damping force control according to the following basic procedure. That is, when the automobile V starts running, the ECU 8 executes damping force control whose procedure is shown in the flowchart of FIG. 18 at a predetermined processing interval (for example, 10 ms). When the damping force control is started, the ECU 8 calculates the unsprung load u ₁ of each wheel based on the detected value of the wheel speed sensor 9 and the calculated unsprung load u ₁ and the detected value of the lateral G sensor 10. based on calculates motion state quantity of the motor vehicle V (sprung speed S ₂ and the stroke speed Ss of each wheel, the roll angular velocity ωr of the vehicle body 1, the pitch angular velocity .omega.p) (steps ST1).

Then, ECU 8, based on the sprung speed _{S 2} and the stroke speed Ss is calculated skyhook control target current Ash of each damper 6 (step ST2), the pitch of the dampers 6 based on the pitch angular velocity ωp of the vehicle body 1 The control target current Ap is calculated (step ST3), the roll control target current Ar of each damper 6 is calculated based on the roll angular velocity ωr of the vehicle body 1 (step ST4), and the steering of each damper 6 is calculated based on the steering steering angle δf. The angular proportional control target current Asa is calculated (step ST5), and the unsprung vibration suppression control target current Au of each damper 6 is calculated based on the wheel speed Vw of each wheel (step ST6), and the wheel speed Vw of each wheel is calculated. Based on this, the minimum target current Amin of each damper 6 is calculated (step ST7). Note that the processes of steps ST2 to ST7 do not have to be performed in this order, or may be performed in parallel.

  Next, the ECU 8 sets the largest value among the six control target currents Ash, Ap, Ar, Asa, Au, and Amin for each wheel as the target current Atgt (step ST8). Thereafter, the ECU 8 determines whether or not the current fixing signal Sfix is input (step ST9), and when this determination is No (that is, when any of VSA, ABS, and TCS is not operating), Based on the target current Atgt selected in step ST8, a drive current is output to the MLV coil of each damper 6 (step ST10). Thereby, in damping force control, the optimal target damping force according to the load of the damper 6 is set, and improvement in steering stability and riding comfort is realized.

  On the other hand, when the determination in step ST9 is Yes (that is, when any of VSA, ABS, and TCS is operating), the ECU 8 applies the MLV coil of each damper 6 based on the target current Atgt of the previous value. A drive current is output (step ST11). As a result, when any one of VSA, ABS, and TCS is operating, the target current Atgt selected in step ST8 is prevented from changing suddenly and the vehicle behavior becoming unstable.

<< Second Embodiment >>
Next, a second embodiment of the suspension control device 20 according to the present invention will be described with reference to FIG. In the description, elements having the same functions as those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted.

≪ECU8≫
In the present embodiment, as shown in FIG. 19, the input unit 21 of the ECU 8 includes a wheel speed Vw, a lateral acceleration Gy, a driving torque Te, a gear position Pg, a brake hydraulic pressure Pb, a yaw rate γ, a steering wheel, and the like. In addition to the steering angle δf, VSA, ABS, and TCS flags, a longitudinal acceleration Gx is input from a longitudinal G sensor (not shown) provided in the vehicle body 1.

The vehicle state quantity estimator 22 includes a state quantity calculator 31 and a vehicle body speed estimator 32. The vehicle body speed estimator 32 is omitted from illustration, but the acceleration / deceleration force calculator 51 and the steering correction are the same as in the first embodiment. A quantity calculation unit 53. On the other hand, the state quantity calculation unit 31 does not include the four-wheel model calculation unit 34 but includes only the one-wheel model calculation unit 33 and the slip determination unit 50. Sprung velocity S ₂ and the stroke speed Ss calculated by the vehicle state quantity estimating unit 22, similarly to the first embodiment, used for calculating the skyhook control target current Ash in the skyhook control unit 90.

  The pitch controller 91 of the present embodiment uses the longitudinal acceleration Gx detected by the longitudinal G sensor to set the pitch control target current Ap based on the differential value. The roll control unit 92 sets the roll control target current Ar based on the differential value using the lateral acceleration Gy detected by the lateral G sensor 10. Note that the unsprung vibration suppression control unit 95 sets the unsprung vibration suppression control target current Au based on each wheel speed Vw as in the first embodiment.

  In the present embodiment, a current suppressing unit 124 is provided instead of the current fixing unit 24 of the first embodiment. The operation signals indicating the operations of ABS, TCS, and VSA are not input to the input unit 21, and the slip signal SS output from the slip determination unit 50 is directly input to the current suppression unit 124. The slip signal SS is also input to a vehicle behavior control unit (not shown) that controls the ABS, TCS, and VSA, and the vehicle behavior control unit controls the ABS, TCS, and VSA in response to the input of the slip signal SS. On the other hand, when the slip signal SS is input, the current suppression unit 124 outputs a suppression signal Sd for suppressing each control target current according to a predetermined rule, assuming that the behavior of the automobile V is unstable.

  The damper control unit 25 of the present embodiment has a target current correction unit 110 and a high current selection / control unit 111 instead of the high current selection unit 108 and the current control unit 109 of the first embodiment. Skyhook control target current Ash, unsprung vibration suppression control target current Au, pitch control target current Ap, rudder angle proportional control target current Asa, roll control target current Ar and minimum target current Amin set by the control target current setting unit 23 Is input to the high current selection / control unit 111 via the target current correction unit 110.

  The target current correction unit 110 also receives a suppression signal Sd output from the current suppression unit 124. When the suppression signal Sd is input, the target current correcting unit 110 keeps the skyhook control target current Ash and the unsprung vibration suppression control target current Au constant at values immediately before the suppression signal Sd is input (that is, the damper 6 Correction (suppression) is performed by fixing the attenuation coefficient to a predetermined value.

  The high current selection / control unit 111 sets the target current Atgt having the largest value among the six control target currents Ash, Au, Ap, Asa, Ar, Amin output from the target current correction unit 110, Based on the set target current Atgt, a drive current to each damper 6 is generated to control the damping force of the damper 6. As described above, the high current selection / control unit 111 is determined to be in the slip state by using the skyhook control target current Ash and the unsprung vibration suppression control target current Au corrected by the target current correction unit 110 as options. A sudden change in the damping force of the damper 6 due to the skyhook control target current Ash and the unsprung vibration suppression control target current Au set depending on the wheel speed Vw is avoided.

  In the present embodiment, the target current correction unit 110 corrects only the skyhook control target current Ash and the unsprung vibration suppression control target current Au, and the unsprung vibration suppression control target current Au, the pitch control target current Ap, and the steering angle. Since the proportional control target current Asa, the roll control target current Ar, and the minimum target current Amin are not corrected, for example, when the vehicle behavior changes in the roll posture, an appropriate roll control target current Ar is output and the vehicle behavior is disturbed. Is suppressed, and control of operation control such as VSA can be improved.

  As a modified example of the target current correction unit 110, when the suppression signal Sd is input, the target current correction unit 110 maintains the skyhook control target current Ash and the unsprung vibration suppression control target current Au constant, and also performs pitch control. The target current Ap, the steering angle proportional control target current Asa, the roll control target current Ar, and the minimum target current Amin may be multiplied by a reduction gain for suppressing control. By setting it as such a form, the control amount of the damper 6 in the state where a vehicle behavior is unstable can be suppressed entirely.

  Alternatively, when the suppression signal Sd is input, the target current correction unit 110 keeps the skyhook control target current Ash and the unsprung vibration suppression control target current Au constant, and the pitch control target current Ap and the steering angle proportional control. The target current Asa, the roll control target current Ar, and the minimum target current Amin may also be maintained constant at values immediately before the suppression signal Sd is input (that is, the damping coefficient of the damper 6 is fixed to a predetermined value). By setting it as such a form, the control amount of the damper 6 in the state where a vehicle behavior is unstable can be suppressed reliably.

  In any form, the current control unit 109 maintains the control target current constant or suppresses the period (duration) during which the suppression signal Sd is input, or the input of the suppression signal Sd. It is the same as in the first embodiment that a predetermined time can elapse after there is no more.

  In addition, the control by which the current control unit 109 maintains or suppresses each control target current to be constant is not limited to a mode in which a constant value is maintained over a continuous period, and each control target current is gradually decreased and reaches a predetermined value after a predetermined time. Depends on the control target current setting unit 23 by setting (fixing) the change of the control target or by setting (fixing) the change of each control target current so as to gradually decrease after maintaining a constant value for a predetermined time. The degree of control performed may be suppressed. Thus, the vehicle behavior can be stabilized by reliably converging the control amount to a constant value after a predetermined time.

≪Damping force control procedure≫
Next, the procedure of damping force control by the ECU 8 according to the second embodiment will be described with reference to FIG.

When starting the damping force control, ECU 8 is configured to calculates the unsprung load u ₁ of each wheel based on the detected value of the wheel speed sensors 9, the calculated on the basis of the unsprung load u _1, motion state quantity of the vehicle V calculating a (sprung speed _{S 2} and the stroke speed Ss of each wheel) (step ST21).

Then, ECU 8, based on the sprung speed _{S 2} and the stroke speed Ss is calculated skyhook control target current Ash of each damper 6 (step ST22), the pitch of the dampers 6 based on the differential value of the longitudinal acceleration Gx The control target current Ap is calculated (step ST23), the roll control target current Ar of each damper 6 is calculated based on the differential value of the lateral acceleration Gy (step ST24), and the steering of each damper 6 is calculated based on the steering angle δf. The angular proportional control target current Asa is calculated (step ST25), and the unsprung vibration suppression control target current Au of each damper 6 is calculated based on the wheel speed Vw of each wheel (step ST26), and the wheel speed Vw of each wheel is calculated. Based on this, the minimum target current Amin of each damper 6 is calculated (step ST27). Note that the processes of steps ST22 to ST27 do not have to be performed in this order, or may be performed in parallel.

  Next, the ECU 8 determines whether or not the suppression signal Sd is input (step ST28). When this determination is No (that is, when it is not determined to be in the slip state), the ECU 8 Is set to the target current Atgt from the six control target currents Ash, Ap, Ar, Asa, Au, and Amin set in steps ST21 to ST27, and each damper is set based on the target current Atgt. The drive current is output to the 6 MLV coils (step ST30). Thereby, in damping force control, the optimal target damping force according to the load of the damper 6 is set, and improvement in steering stability and riding comfort is realized.

  On the other hand, when the determination in step ST29 is Yes (that is, when it is determined as a slip state), the skyhook control target current Ash and the unsprung vibration suppression control target current Au are corrected (suppressed) based on the previous values. (Step ST29), after setting the largest control value among the six control target currents Ash, Ap, Ar, Asa, Au, and Amin for each wheel as the target current Atgt, A drive current is output to the MLV coil of the damper 6 (step ST30). As a result, when the vehicle V is in a slip state and any of VSA, ABS, and TCS is operating, the target of each damper 6 is abruptly changed by the control target currents Ash and Au set in steps ST22 and ST26. It is prevented that the current Atgt changes suddenly and the vehicle behavior becomes unstable.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, the specific configuration and arrangement of each member and part, or the specific procedure of control can be changed as appropriate without departing from the spirit of the present invention. On the other hand, all the constituent elements according to the present invention shown in the above embodiment are not necessarily essential, and can be appropriately selected.

V Automobile (vehicle)
6 Damper (Damping force variable damper)
8 ECU
9 Wheel speed sensor 20 Suspension control device 23 Control target current setting section (damper control means)
25 Damper control unit (damper control means)
33 One-wheel model calculation part (state quantity calculation means)
37 Gain circuit (basic input amount calculation means)
38 One-wheel model (vehicle model)
43 First observation matrix (position calculation means)
44 Second observation matrix (position calculation means)
47 PID circuit Vw Wheel speed (input signal)
ΔVw Wheel speed fluctuation u ₁ Unsprung load (basic input)
u ₂ damping force S ₂ sprung speed (state quantity)
Ss Stroke speed (state quantity)
x ₁ unsprung position x ₂ unsprung position

Claims (1)

A suspension control device for a vehicle including a damping force variable damper capable of adjusting a damping force according to an input signal,
A wheel speed sensor for detecting the wheel speed of each wheel;
Basic input amount calculation means for calculating an unsprung load as a basic input amount of the vehicle based on wheel speed fluctuation detected by the wheel speed sensor;
State quantity calculating means for calculating the state quantity of the vehicle by inputting the unsprung load and the damping force of the damping force variable damper to a vehicle model representing the behavior of the vehicle;
Damper control means for controlling the damping force of the damping force variable damper based on the calculated state quantity;
Position calculating means for calculating at least one of an unsprung position and an unsprung position of the vehicle based on the vehicle model;
By feeding back at least one of the sprung position and the unsprung position to the vehicle model, the sprung position and the unsprung position of the vehicle model in a steady state are converged to an initial value. Suspension control device.

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