Control device

Abstract

This controller comprises: a weighting coefficient calculation unit that, when an actual target damping force is calculated on the basis of a calculated value from a vehicle behavior calculation unit, calculates a weighting coefficient for making the actual target damping force approach a value close to a predetermined target damping force; a vertical movement calculation unit that determines the vertical-direction movement state of a vehicle; a pitch movement calculation unit that determines the pitch-direction movement state of the vehicle; an actual target damping force calculation unit that calculates the actual target damping force on the basis of the weighting coefficient from the weighting coefficient calculation unit and the calculation results of the vertical movement calculation unit and the pitch movement calculation unit; a target damping coefficient calculation unit that calculates a target damping coefficient on the basis of the value calculated by the actual target damping force calculation unit; a correction unit that calculates a corrected damping coefficient produced by lowering an upper limit of the target damping coefficient in a low-speed range in which the relative speed between sprung and unsprung parts of the vehicle is below a prescribed value; and a control signal output unit that outputs a control signal corresponding to the corrected damping coefficient to a damping force regulating-type shock absorber.

Description

Control device

[0001] The present disclosure relates to a control device for controlling a damping force adjustable shock absorber for a four-wheeled vehicle, for example.

[0002] There are known control devices for controlling an adjustable damping shock absorber that is disposed between the vehicle body and the wheels of a vehicle (see Patent Documents 1 and 2). The control devices of the prior art control the damping force of the adjustable damping shock absorber so as to suppress vibrations of the vehicle body in the vertical direction.

[0003] JP 2014-69759 A JP 2011-131876 A

[0004] Conventional control devices have performed, for example, bilinear optimal control (BLQ) to suppress vertical vibrations of the vehicle body. In this case, it is preferable to be able to suppress pitch vibrations in addition to vertical (heave) vibrations. However, in order to suppress pitch vibrations in addition to vertical vibrations using BLQ, optimization must be performed using a full vehicle model, which poses a problem of poor tunability. Meanwhile, skyhook control is known to utilize gain scheduling parameters (GSP). However, applying GSP to BLQ results in two controllers, which poses a problem of poor controllability.

[0005] An object of the present invention is to provide a control device for an adjustable damping force shock absorber that can suppress vertical and pitch vibrations while ensuring tunability.

[0006] One embodiment of the present invention is a control device for a damping force adjustable shock absorber that is provided in a vehicle and is capable of adjusting the damping force generated, the control device including: a weighting coefficient calculation unit that calculates a weighting coefficient for making the actual target damping force approach a value close to a pre-determined target damping force when calculating an actual target damping force based on a calculated value of a vehicle behavior calculation unit; a vertical movement calculation unit that calculates a vertical movement state of the vehicle; a pitch movement calculation unit that calculates a pitch movement state of the vehicle; an actual target damping force calculation unit that calculates the actual target damping force based on the weighting coefficient calculated by the weighting coefficient calculation unit and the calculation results of the vertical movement calculation unit and the pitch movement calculation unit; a target damping coefficient calculation unit that calculates a target damping coefficient based on the calculated value of the actual target damping force calculation unit; and a weighting coefficient calculation unit that calculates a weighting coefficient for adjusting a relationship between a sprung part and an unsprung part of the vehicle. and a control signal output unit that outputs a control signal corresponding to the corrected damping coefficient to the damping force adjustable shock absorber, wherein the correction unit sets the corrected damping coefficient so that the damping force increases as the relative speed increases, and that the slope of the damping force with respect to the relative speed is small when the relative speed is slower than the predetermined value and the slope of the damping force with respect to the relative speed is large when the relative speed is faster than the predetermined value, and the correction unit has a maximum damping coefficient corresponding to the relative speed, and corrects the target damping coefficient to the maximum damping coefficient when the target damping coefficient exceeds the maximum damping coefficient.

[0007] According to one embodiment of the present invention, it is possible to suppress vibrations in the vertical direction and in pitch while ensuring tunability.

[0008] 16 is an overall configuration diagram showing a four-wheeled vehicle to which a controller according to an embodiment of the present invention is applied. FIG. 17 is a diagram schematically showing a vehicle behavior control device according to an embodiment of the present invention. FIG. 18 is a control block diagram showing a controller according to a first embodiment. FIG. 19 is a block diagram showing a GSP calculation unit in FIG. 3. FIG. 19 is a block diagram showing a BLQ controller in FIG. 3. FIG. 19 is an explanatory diagram showing a damping coefficient upper limit calculation unit in FIG. 5. FIG. 20 is an explanatory diagram showing a command value calculation unit in FIG. 5. FIG. 21 is a block diagram showing a target damping force calculation unit and a corrected damping coefficient calculation unit in FIG. 5. FIG. 22 is a block diagram showing a sprung vertical vibration damping BLQ in FIG. 5. FIG. 23 is a block diagram showing a roll vibration damping BLQ in FIG. 5. FIG. 24 is a block diagram showing a pitch vibration damping BLQ in FIG. 25. FIG. 26 is a characteristic line diagram showing an example of time changes in sprung displacement, sprung acceleration, pitch angle, right front wheel command current, and right rear wheel command current for the first embodiment and a comparative example. FIG. 27 is a control block diagram showing a controller according to a second embodiment. FIG. 28 is a block diagram showing a GSP calculation unit in FIG. Fig. 19 is a control block diagram showing a controller according to a third embodiment. Fig. 19 is a block diagram showing a BLQ controller in Fig. 18. Fig. 19 is a block diagram showing a sprung vertical vibration damping BLQ in Fig. 19. Fig. 19 is a block diagram showing a roll vibration damping BLQ in Fig. 19. Fig. 19 is a block diagram showing a pitch vibration damping BLQ in Fig. 19.

[0009] Hereinafter, a control device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where the control device is applied to a four-wheeled vehicle.

[0010] Fig. 1 shows a vehicle to which a controller 11, which is a control device, is applied. A vehicle behavior control device 1 including the controller 11 is applied to this vehicle. As shown in Fig. 2, the vehicle behavior control device 1 is made up of a suspension device 5 constituting a damping force generating device and the controller 11 constituting a vehicle control device. In Fig. 2, for example, left and right front wheels and left and right rear wheels (hereinafter collectively referred to as wheels 3) are provided on the underside of a vehicle body 2 constituting the body of the vehicle. The wheels 3 are made up of tires 4, which act as springs to absorb small irregularities in the road surface.

[0011] The suspension device 5 is provided between the vehicle body 2 and the vehicle wheel 3. The suspension device 5 is composed of a suspension spring 6 (hereinafter referred to as the spring 6) and an adjustable damping force shock absorber (hereinafter referred to as the variable damper 7) provided in parallel with the spring 6 between the vehicle body 2 and the wheel 3.

[0012] 2 shows a case where one set of suspension devices 5 is provided between the vehicle body 2 and the wheels 3. However, a total of four sets of suspension devices 5 are provided individually and independently between, for example, four wheels 3 and the vehicle body 2, and only one of these sets is shown schematically in FIG.

[0013] Here, the variable damper 7 of the suspension device 5 is configured using a damping force adjustable hydraulic shock absorber interposed between the vehicle body 2 and the wheel 3. This variable damper 7 is provided with a damping force variable actuator 8, which is composed of a damping force adjustment valve or the like, for continuously adjusting the characteristics of the generated damping force (i.e., the damping force characteristics) from hard characteristics to soft characteristics. The variable damper 7 constitutes a force generating mechanism that generates an adjustable force between the vehicle body 2 and the wheel 3. Note that the damping force variable actuator 8 does not necessarily have to be configured to continuously adjust the damping force characteristics, and may be capable of adjusting the damping force in multiple stages, for example, two or more stages. Furthermore, the variable damper 7 may be a pressure control type or a flow rate control type. The variable damper 7 may also be a type that controls viscosity, such as a magnetorheological fluid or an electrorheological fluid.

[0014] The controller 11 constitutes a control device for the variable damper 7 and controls the damping characteristics of the variable damper 7. The controller 11 is configured, for example, by a microcomputer. The controller 11 is connected, for example, to a CAN 9 (Controller Area Network), which is a line network required for data communication. The controller 11 acquires vehicle driving parameters via the CAN 9. At this time, the vehicle driving parameters include, for example, wheel speed, slip ratio, longitudinal acceleration, engine torque, brake fluid pressure, road surface friction coefficient, and four-wheel independent braking / driving force control flags. The output side of the controller 11 is connected to the damping force variable actuator 8 of the variable damper 7.

[0015] The controller 11 also has a storage unit 11A including a ROM, a RAM, a non-volatile memory, etc. The storage unit 11A of the controller 11 stores various programs, information (vehicle information), data, etc. for controlling the variable damper 7.

[0016] As shown in FIG. 3 , the controller 11 includes a state estimation unit 12 , a GSP calculation unit 13 , and a BLQ controller 20 .

[0017] The state estimation unit 12 estimates the vehicle state (vehicle motion, vehicle behavior) using the CAN signal. That is, the state estimation unit 12 estimates the sprung-unsprung relative velocity, the vehicle body absolute vertical velocity (sprung velocity), the unsprung-road relative velocity, the unsprung absolute vertical velocity (unsprung velocity), the roll rate, the roll angle, the pitch rate, and the pitch angle based on the signal (CAN signal) flowing through the CAN 9. For example, the state estimation unit 12 estimates the sprung-unsprung relative velocity, the vehicle body absolute vertical velocity, the unsprung-road relative velocity, the unsprung absolute vertical velocity, the roll rate, the roll angle, the pitch rate, and the pitch angle based on the steering angle of the vehicle, the longitudinal acceleration, the lateral acceleration, the yaw rate, the wheel speeds of each wheel 3, the presence or absence of brake operation, and the master cylinder hydraulic pressure.

[0018] In addition, the technology for estimating the sprung-unsprung relative velocity, vehicle body absolute vertical velocity, unsprung-road relative velocity, unsprung absolute vertical velocity, roll rate, roll angle, pitch rate, pitch angle, etc. using a vehicle model (equation of motion) that models the vehicle from longitudinal acceleration, lateral acceleration, yaw rate, wheel speed, etc., and a Kalman filter, etc., is described in various documents (documents related to estimation of vehicle state) including, for example, JP 2012-47553 A, and therefore further explanation will be omitted.

[0019] The state estimation unit 12 constitutes a vehicle behavior calculation unit that calculates vehicle behavior. Specifically, the state estimation unit 12 includes a vertical movement calculation unit that calculates a state related to the vertical movement of the vehicle. The state estimation unit 12 includes a roll movement calculation unit that calculates a state related to the roll movement of the vehicle. The state estimation unit 12 includes a pitch movement calculation unit that calculates a state related to the pitch movement of the vehicle. The state estimation unit 12 includes an attitude change detection unit that detects changes in the attitude of the vehicle body.

[0020] The state estimation unit 12 outputs signals corresponding to the estimated state values ​​(motion values), i.e., the relative velocity between the sprung and unsprung parts, the absolute vertical velocity of the vehicle body, the relative velocity between the unsprung part and the road surface, the absolute vertical velocity of the unsprung part, the roll rate, the roll angle, the pitch rate, the pitch angle, etc., to the BLQ controller 20.

[0021] The vehicle behavior calculation unit may be various sensors that detect the sprung speed, roll rate, pitch rate, etc. The vehicle behavior calculation unit may also estimate the sprung acceleration, roll rate, pitch rate, etc. based on the wheel speed and road surface information (preview) in the traveling direction of the vehicle.

[0022] The GSP calculation unit 13 (gain scheduling parameter calculation unit) constitutes a weighting coefficient calculation unit that calculates weighting coefficients that make the actual target damping force based on the calculated value of the state estimation unit 12 (vehicle behavior calculation unit) closer to a predetermined target damping force. The GSP calculation unit 13 calculates the heave GSP, roll GSP, and r , Pitch GSP pThe heave GSP is a weighting coefficient that adjusts the heave target damping force to suppress the vertical movement of the vehicle. r is a weighting coefficient for adjusting the roll target damping force for suppressing the roll direction movement of the vehicle. p is a weighting coefficient for adjusting the pitch target damping force for suppressing the motion of the vehicle in the pitch direction.

[0023] That is, when the BLQ controller 20 calculates an actual target damping force based on the vehicle state (for example, sprung-unsprung relative velocity, vehicle body absolute vertical velocity, unsprung-road relative velocity, unsprung absolute vertical velocity, roll rate, roll angle, pitch rate, pitch angle, etc.) calculated by the state estimation unit 12 (vehicle behavior calculation unit), the GSP calculation unit 13 calculates a weighting coefficient (heave GSP, roll GSP) that brings this actual target damping force close to a target damping force calculated in advance. r , Pitch GSP p The GSP calculation unit 13 calculates the heave GSP, the roll GSP, r , Pitch GSP p is output to the BLQ controller 20.

[0024] As shown in Figure 4, the GSP calculation unit 13 is provided with a lookup table that records, for example, the relationship between vehicle speed and heave GSP. At this time, the heave GSP is determined by tuning in an actual vehicle test. Specifically, the heave GSP is fine-tuned by referring to vibration data, etc., after the rough characteristics are determined by subjective evaluation in an actual vehicle test. The GSP calculation unit 13 also has a lookup table that records the relationship between vehicle speed and roll GSP, and a lookup table that records the relationship between vehicle speed and pitch GSP. Roll GSP r , Pitch GSP p Like the heave GSP, this is determined by tuning in actual vehicle tests.

[0025] Heave GSP, Roll GSP r , Pitch GSP p are normalized values ​​between 0 and 1. Heave GSP, Roll GSP r , Pitch GSP pAs shown in FIG. 4, for example, the heave GSP and roll GSP are small at low speeds and large at high speeds. r , Pitch GSP p is not limited to this, and may be a constant value that remains the same regardless of the vehicle speed.

[0026] The BLQ controller 20 calculates a command current (control signal) that serves as a command value based on bilinear optimal control theory. As shown in Fig. 5, the BLQ controller 20 includes a sprung vertical vibration damping BLQ 21, a roll vibration damping BLQ 22, a pitch vibration damping BLQ 23, a target damping force calculation unit 24, a damping coefficient upper limit calculation unit 25, a corrected damping coefficient calculation unit 26, and a command value calculation unit 29.

[0027] The sprung mass vertical damping BLQ21 receives as input the vehicle state output from the state estimation unit 12 and the heave GSP output from the GSP calculation unit 13. The sprung mass vertical damping BLQ21 calculates a heave target damping force of the variable damper 7 for reducing vertical vibrations based on the sprung-unsprung mass relative velocity, vehicle body absolute vertical velocity, unsprung mass-road surface relative velocity, and unsprung mass absolute vertical velocity output from the state estimation unit 12, and the heave GSP output from the GSP calculation unit 13. The sprung mass vertical damping BLQ21 is designed based on the vehicle model shown in FIG. 12, for example. FIG. 12 illustrates an example in which one set of suspension devices 5 is provided between the vehicle body 2 and the wheels 3. However, a total of four sets of suspension devices 5 are provided individually and independently between, for example, four wheels 3 and the vehicle body 2, and only one of these sets is schematically illustrated in FIG. 12. The sprung vertical vibration damper BLQ21 is designed based on the state equation of the vehicle model shown in FIG. 12, as will be described later in the design method.

[0028] As shown in FIG. 9 , the sprung vertical vibration damping BLQ21 includes a Bp calculation unit 21A, a multiplier 21B, a Bp calculation unit 21C, a multiplier 21D, a multiplier 21E, and a heave target damping force calculation unit 21F. The Bp calculation unit 21A calculates the maximum value of Bp according to the relative speed based on the previously calculated Bp and the heave GSP. The multiplier 21B multiplies the maximum value of Bp output from the Bp calculation unit 21A by the relative speed. The Bp calculation unit 21C calculates the maximum value of Bp according to the sprung speed based on the previously calculated Bp and the heave GSP. The multiplier 21D multiplies the maximum value of Bp output from the Bp calculation unit 21C by the sprung speed. The multiplier 21E multiplies the value calculated by the multiplier 21B by the value calculated by the multiplier 21D. The heave target damping force calculation unit 21F multiplies the value calculated by the multiplier 21E by the inverse matrix of R (R -1 ) to calculate the target heave damping force. In this way, the sprung vertical vibration damping BLQ21 calculates a value obtained by multiplying the right side of equation (12) described below by the relative velocity from the left. As a result, the sprung vertical vibration damping BLQ21 calculates the target heave damping force by multiplying the left side of equation (12) described below by the relative velocity from the left. Note that, although the sprung vertical vibration damping BLQ21 has calculated the target heave damping force based on Bp corresponding to the relative velocity and Bp corresponding to the sprung velocity, the present invention is not limited to this. The sprung vertical vibration damping BLQ21 may calculate the target heave damping force based on Bp corresponding to other vehicle conditions in addition to Bp corresponding to the relative velocity and sprung velocity.

[0029] The roll vibration suppression BLQ 22 receives the vehicle state output from the state estimation unit 12 and the roll GSP output from the GSP calculation unit 13. r The roll vibration suppression BLQ 22 receives the roll rate and roll angle output from the state estimation unit 12 and the roll GSP output from the GSP calculation unit 13. rBased on this, a target roll damping force of the variable damper 7 for reducing roll vibration is calculated. The roll damping BLQ 22 is designed based on, for example, the vehicle model shown in FIG. 13. FIG. 13 shows an example of a simplest vehicle model that takes roll into consideration, a one-degree-of-freedom rotational motion model. In an actual vehicle, a total of two sets of this motion model are provided, one for the front wheels and one for the rear wheels, and only one of these sets is shown schematically in FIG. 13. The roll damping BLQ 22 is designed based on the state equation of the vehicle model in FIG. 13, as will be shown in the design method described below.

[0030] As shown in Fig. 10, the roll vibration suppression BLQ 22 includes a Bp calculation unit 22A, a multiplier 22B, and a roll target damping force calculation unit 22C. roll p roll and Roll GSP r Based on this, B according to the roll rate roll p roll The multiplier 22B calculates the maximum value of B roll p roll The roll target damping force calculation unit 22C multiplies the value calculated by the multiplier 22B and the previously calculated R roll The inverse matrix (R roll -1 ) to calculate the target roll damping force. In this way, the roll vibration suppression BLQ 22 calculates a value obtained by multiplying the right side of equation 20 (described later) by the relative velocity from the left side. As a result, the roll vibration suppression BLQ 22 calculates the target roll damping force by multiplying the left side of equation 20 (described later) by the roll rate from the left side.

[0031] The pitch vibration damping BLQ 23 is based on the vehicle state output from the state estimation unit 12 and the pitch GSP output from the GSP calculation unit 13. p The pitch damping BLQ 23 receives the pitch rate and pitch angle output from the state estimation unit 12 and the pitch GSP output from the GSP calculation unit 13. pBased on this, a pitch target damping force of the variable damper 7 for reducing pitch vibration is calculated. The pitch vibration damping BLQ 23 is designed based on, for example, the vehicle model shown in FIG. 14. FIG. 14 illustrates the simplest vehicle model that takes pitch vibration into consideration, a one-degree-of-freedom rotational motion model. In an actual vehicle, a total of two sets of this motion model are provided, one on the left side and one on the right side, and only one of these sets is schematically illustrated in FIG. 14. The pitch vibration damping BLQ 23 is designed based on the state equation of the vehicle model in FIG. 14, as will be shown in the design method described below.

[0032] As shown in Fig. 11, the pitch vibration damping BLQ 23 includes a Bp calculation unit 23A, a multiplier 23B, and a pitch target damping force calculation unit 23C. pitch p pitch and Pitch GSP p Based on this, B according to the pitch rate pitch p pitch The multiplier 23B calculates the maximum value of B pitch p pitch The pitch target damping force calculation unit 23C multiplies the value calculated by the multiplier 23B and the previously calculated R pitch The inverse matrix (R pitch -1 ) to calculate the pitch target damping force. In this way, the pitch vibration suppression BLQ 23 calculates a value obtained by multiplying the right side of Equation 27 (described later) by the relative velocity from the left side. As a result, the pitch vibration suppression BLQ 23 calculates the pitch target damping force by multiplying the left side of Equation 27 (described later) by the pitch rate from the left side.

[0033] The target damping force calculation unit 24 calculates the actual target damping force of each variable damper 7 based on the three target damping forces (heave target damping force, roll target damping force, pitch target damping force) output from the sprung vertical damping BLQ21, the roll damping BLQ22, and the pitch damping BLQ23 (see FIG. 5). The sprung vertical damping BLQ21, the pitch damping BLQ23, and the target damping force calculation unit 24 calculate the actual target damping force of each variable damper 7 based on the heave GSP and roll GSP calculated by the GSP calculation unit 13 (weighting coefficient calculation unit). r , Pitch GSP p(weighting coefficient) and an actual target damping force calculation section that calculates an actual target damping force based on the calculation results of the state estimation section 12 (vertical movement calculation section, pitch movement calculation section).

[0034] 8, the target damping force calculation unit 24 includes an adder 24A and a damping force dead-zone calculation unit 24B. The adder 24A adds the heave target damping force from the sprung vertical damping BLQ 21, the roll target damping force from the roll damping BLQ 22, and the pitch target damping force from the pitch damping BLQ 23, and calculates the sum of these BLQ target damping forces.

[0035] The damping force dead band calculation unit 24B sets a dead band for the BLQ target damping force output from the adder 24A. The damping force dead band calculation unit 24B outputs the actual target damping force set in the dead band for the BLQ target damping force.

[0036] In bilinear optimal control (BLQ), control is activated even for small road inputs, so there is a risk that a high damping force will be generated in response to a small road input, which may result in a deterioration in ride comfort. Therefore, the damping force dead zone calculation unit 24B sets a dead zone for the BLQ target damping force. This prevents control from being activated for a small target damping force.

[0037] If the control gain of the BLQ varies depending on the vehicle speed, the dead band is set in accordance with the vehicle speed in the dead band selection process.If the control gain of the BLQ varies depending on the car mode, the dead band is set in accordance with the car mode in the dead band selection process.

[0038] When traveling on an undulating road, if the sprung velocity or relative displacement crosses zero, the target damping force becomes small, and if a damping force dead band is set at this time, the control amount will not be output, resulting in a deterioration in vibration damping. Therefore, in order to prioritize vibration damping when traveling on an undulating road, a relaxation process is performed to reduce the dead band of the temporary BLQ damping force dead band when the undulating road index is high, so that a control amount is output even with a small target damping force. Furthermore, to improve tuning performance, the dead band relaxation process may be enabled or disabled.

[0039] Although the target damping force calculation unit 24 adds the heave target damping force, the roll target damping force, and the pitch target damping force, the present invention is not limited to this. For example, the target damping force calculation unit 24 may select the largest value among the heave target damping force, the roll target damping force, and the pitch target damping force.

[0040] The damping coefficient upper limit calculation unit 25 calculates the maximum damping coefficient Cmax, which is the upper limit of the damping coefficient C. As shown in Fig. 6, the damping coefficient upper limit calculation unit 25 is a maximum damping coefficient map that calculates the maximum damping coefficient Cmax based on the vehicle state. For example, the damping coefficient upper limit calculation unit 25 calculates the maximum damping coefficient Cmax based on the relative velocity x between the sprung mass and the unsprung mass. * The damping coefficient upper limit calculation unit 25 has a characteristic line 25A that shows the relationship between the relative velocity x * The maximum damping coefficient Cmax is set to a value within a range that does not exceed the maximum value of the damping coefficient that can be generated by the variable damper 7. The maximum damping coefficient Cmax is calculated based on the relative velocity x * is set to a small value when the relative velocity x is lower than a predetermined threshold value Vt. * is set to a large value when the speed is faster than the threshold Vt.

[0041] Specifically, the relative velocity x * is slower than the threshold Vt (-Vt<x * < Vt), the maximum damping coefficient Cmax is set to a small low-speed setting value C1. On the other hand, when the relative speed x * When is faster than the threshold Vt (x * > Vt), the maximum damping coefficient Cmax is set to a high speed setting value C2 that is greater than the low speed setting value C1. Similarly, when the relative speed x * When is faster than the threshold Vt (x * <-Vt), the maximum damping coefficient Cmax is set to a high speed setting value C3 which is greater than the low speed setting value C1.

[0042] Relative velocity x * When the relative velocity x is close to the threshold value Vt, the maximum damping coefficient Cmax may be set to a value between the low speed setting value C1 and the high speed setting value C2.* When Vt approaches the threshold value (-Vt), the maximum damping coefficient Cmax may be set to a value between the low speed setting C1 and the high speed setting C3.

[0043] The high-speed setting values ​​C2 and C3 are set appropriately in consideration of the structure, specifications, damping force characteristics, etc. of the variable damper 7. In addition, although the low-speed setting value C1 and the high-speed setting values ​​C2 and C3 are all constant values ​​in the above example, the relative speed x * It may be configured to change depending on the

[0044] The threshold value Vt is obtained experimentally, taking into consideration the occurrence of jerk, and is set appropriately depending on the structure of the variable damper 7, the damping force characteristics, etc. The threshold value Vt is also calculated based on the relative velocity x * The positive and negative sides of the relative velocity x * The positive and negative sides may be set to different values.

[0045] The corrected damping coefficient calculation unit 26 calculates a target damping coefficient C corresponding to the actual target damping force, and outputs a corrected damping coefficient Ca based on this target damping coefficient C and the maximum damping coefficient Cmax (see FIG. 8). The corrected damping coefficient calculation unit 26 includes a target damping coefficient calculation unit 27 and a minimum value selection unit 28.

[0046] The target damping coefficient calculation unit 27 constitutes a target damping coefficient calculation unit that calculates a target damping coefficient C based on the calculated value of the actual target damping force calculation unit. The target damping coefficient calculation unit 27 calculates the target damping coefficient C corresponding to the actual target damping force output from the target damping force calculation unit 24. Specifically, the target damping coefficient calculation unit 27 is constituted by a divider, and calculates the target damping coefficient C from the actual target damping force by dividing the relative velocity x * The target damping coefficient C is calculated by dividing the above equation.

[0047] The minimum value selection unit 28 compares the target damping coefficient C output from the target damping coefficient calculation unit 27 with the maximum damping coefficient Cmax output from the damping coefficient upper limit calculation unit 25, selects the smaller of these coefficients C and Cmax, and outputs it as the corrected damping coefficient Ca. For this reason, the minimum value selection unit 28 and the damping coefficient upper limit calculation unit 25 select the smaller value of the relative velocity x between the sprung and unsprung parts of the vehicle. *In the low speed region, the correction section calculates a corrected damping coefficient Ca by lowering the upper limit of the target damping coefficient C.

[0048] At this time, the correction unit calculates the correction damping coefficient Ca by multiplying the relative speed x * The damping force increases as the relative velocity x * When the relative velocity x * The slope of the damping force with respect to the relative velocity x is small. * When is fast, the relative velocity x * In addition, the correction unit sets the slope of the damping force to be large with respect to the relative velocity x * When the target damping coefficient C exceeds the maximum damping coefficient Cmax, the target damping coefficient C is corrected to the maximum damping coefficient Cmax.

[0049] The command value calculation unit 29 constitutes a control signal output unit that outputs a control signal corresponding to the corrected damping coefficient Ca to the variable damper 7 (damping force adjustable shock absorber). The command value calculation unit 29 outputs a command current value I as a control signal corresponding to the corrected damping coefficient Ca. As shown in FIG. 7, the command value calculation unit 29 calculates the relationship between the corrected damping coefficient Ca and the command current value I in terms of the relative velocity x * This damping coefficient map was created based on test data by the inventors. The command value calculation unit 29 calculates the corrected damping coefficient Ca and the relative speed x * Based on the above, a command current value I for adjusting the damping force characteristics of the variable damper 7 is specified, and this command current value I is output to the damping force variable actuator 8 of the variable damper 7.

[0050] Furthermore, the command value calculation unit 29 outputs a control signal (command current value I) for controlling the variable damper 7 so as to conform the damping force adjustable shock absorber to the skyhook theory, for example. This command value calculation unit 29 has a hard-side characteristic line 29A shown by a solid line in Fig. 7 and a soft-side characteristic line 29B shown by a dashed line in Fig. 7. In this case, the hard-side characteristic line 29A is positioned in a range where the corrected damping coefficient Ca is larger than that of the soft-side characteristic line 29B.

[0051] And the relative velocity x *When the corrected damping coefficient Ca is input, the corrected damping coefficient Ca and the relative velocity x are calculated in the damping coefficient map of the command value calculation unit 29. * The intersecting point is determined. When this intersecting point is located in a range where the corrected damping coefficient Ca is larger than the hard-side characteristic line 29A, the command current value I is increased to set the damping force characteristics to hard characteristics. On the other hand, when the intersecting point is located in a range where the corrected damping coefficient Ca is smaller than the soft-side characteristic line 29B, the command current value I is decreased to set the damping force characteristics to soft characteristics. Furthermore, when the intersecting point is located in a range between the hard-side characteristic line 29A and the soft-side characteristic line 29B, the command current value I is adjusted according to the corrected damping coefficient Ca, and the damping force characteristics are set to characteristics intermediate between hard and soft.

[0052] As described above, the damping force generated by the variable damper 7 is variably adjusted continuously or in multiple stages between hard and soft in accordance with the command current value I supplied to the damping force variable actuator 8 .

[0053] Next, a method for designing the sprung vertical vibration damping BLQ21, the roll vibration damping BLQ22, and the pitch vibration damping BLQ23 will be described, along with a description of tuning these damping elements using gain scheduling parameters (GSP).

[0054] (1) Design of the vertical movement control system (sprung mass vertical vibration damping BLQ21) A control design model (1 / 4 vehicle model) for vertical movement is shown in Figure 12. Here, the absolute vertical displacement of the car body 2 (sprung mass) is z b , the absolute vertical displacement of the unsprung mass is z t , the absolute vertical displacement of the road surface is z0, the sprung mass (vehicle mass) is m b , unsprung mass m t , the spring constant between the vehicle body 2 and the unsprung part (sprung-unsprung part) is k s , tire spring constant k t The damper damping coefficient is c, and the control force acting between the sprung and unsprung masses is f. Considering that the control force f acts in addition to the soft damping force characteristics, the damper damping coefficient c is set to the damping coefficient of the soft damping force characteristics.

[0055] At this time, the relative displacement between the sprung mass and unsprung mass is z bt , the relative displacement between the unsprung mass and the road surface is z t0Then, the relative displacement z bt , z t0 The state equations are as shown in the following equations 1 to 3. In the state equations, the state variable x and the output y are as shown in equations 4 and 5. A dot in the equations means a first-order derivative with respect to time t (d / dt). Two dots mean a second-order derivative (d / dt).

[0056]

[0057]

[0058]

[0059]

[0060]

[0061] The external force u acting between the vehicle body 2 and the unsprung mass is the control force f (u=f), and the disturbance w is the detected road surface displacement z (w=z). The elements of the state equation are as shown in Equation 6.

[0062]

[0063] Based on the above-mentioned state equation, we will explain the design method of the vertical movement control system (sprung vertical vibration damping BLQ21) based on the bilinear optimal control theory. In the above-mentioned state equation, the control force f was used, but in the case of a bilinear system, the input is expressed as the damping coefficient u c Therefore, the formula 3 is written as the following equation of state:

[0064]

[0065] Here, x * Since is a matrix including the state variable x, the control force f is calculated by the damping coefficient input u c When expressed as a relative velocity, it becomes Equation 8. In this case, x * is as shown in Equation 9.

[0066]

[0067]

[0068] Generally, when the input is irregular, the state variables become random variables, so the evaluation function uses the formula (10) expressed as an expected value. However, the state quantities (sprung-unsprung relative displacement, sprung velocity, unsprung-road relative displacement, unsprung velocity) are used in the evaluation function. Also, C T QC is the weighting matrix for the outputs, and R is the weighting matrix for the inputs.

[0069]

[0070] Here, the optimal control input u that satisfies Equation 11 is c 0 The above problem is solved by dynamic programming, and the optimal control input u c 0 is considered as a steady state problem, the optimal control input u c 0 is calculated as in equation (12).

[0071]

[0072]

[0073] However, p in Equation 12 is a unique positive definite solution of Equation 13.

[0074]

[0075] Here, the values ​​of Q and R of the sprung vertical vibration damper BLQ21 are set to the values ​​shown in Equation 14, and p is calculated.

[0076]

[0077] (2) Design of the roll motion control system (roll vibration suppression BLQ 22) Similar to the above-mentioned vertical motion control system, the roll vibration suppression BLQ 22 is designed based on bilinear control theory. The motion model is a one-degree-of-freedom rotational motion model shown in Figure 13, which is the simplest vehicle model that takes roll into consideration.

[0078] Here, the roll angle of the vehicle body is θ, and the absolute vertical displacement of the left and right wheels on the road surface is x 0l , x 0r , the vehicle body roll inertia is I, the spring constant between the sprung and unsprung parts is k s , the spring constant of the stabilizer is k st, the damping coefficient of the damper is c, and the external force acting between the sprung and unsprung parts at the left and right wheels is F r , F l From FIG. 13, the equation of motion in the roll direction is derived as shown in Equation 15.

[0079]

[0080] Since the system is a bilinear system, the state equation is as shown in Equation 16.

[0081]

[0082] Here, since it is a bilinear system, the external force is the damping coefficient input c of the left and right wheels. r , c l When expressed in terms of relative velocity, it becomes Equation 17.

[0083]

[0084] Also, the state variable x roll , x * roll and the control force u croll And disturbance lol roll are set as shown in Equation 18.

[0085]

[0086] At this time, each element of the state equation is as shown in Equation 19.

[0087]

[0088] From this state equation, the optimal control input u 0 croll is obtained as Equation 20.

[0089]

[0090] However, p in Eq. roll is a unique positive definite solution of Eq. 21.

[0091]

[0092] Here, the Q of the roll vibration damping BLQ22 roll and R roll are set to the values ​​shown in Equation 22, and p rollwas calculated.

[0093]

[0094] (3) Design of the pitch motion control system (pitch vibration suppression BLQ 23) Similar to the control systems for the vertical motion and roll motion described above, the pitch vibration suppression BLQ 23 is designed based on bilinear control theory. The motion model is the simplest one-degree-of-freedom rotational motion model as a vehicle model taking pitch into consideration, as shown in Figure 14.

[0095] Here, the vertical forces acting on the vehicle body from the front and rear suspensions are F Fr , F Rr , the front and rear spring constants are k Fr , k Rr , the front and rear reduction coefficients are c Fr , c Rr , the horizontal distance from the center of gravity to the front and rear suspension is L Fr , L Rr , pitch angle is Φ, front and rear vehicle height displacement is x 2Fr , x 2Rr , front and rear road surface height x 0Fr , x 0Rr , the vertical force generated by the front and rear actuators F FrAct , F RrAct and the moment of inertia of the sprung mass in the pitch direction around the 1 / 2 center of gravity and I yy From FIG. 14, the equation of motion in the roll direction is derived as shown in Equation 23.

[0096]

[0097] Here, the state equation for the bilinear system is set as shown in Equation 24.

[0098]

[0099] Also, the state variable x pitch , x * pitch and the control force u cpitch And disturbance lol pitch are set as shown in Equation 25.

[0100]

[0101] In this case, each element of the state equation is as shown in Equation 26.

[0102]

[0103] From this state equation, the optimal control input u 0 cpitch is obtained as Equation 27.

[0104]

[0105] However, p in Equation 27 pitch is a unique positive definite solution of Eq. 28.

[0106]

[0107] Here, the Q of the pitch damping BLQ23 pitch and R pitch are set to the values ​​shown in Equation 29, and p pitch was calculated.

[0108]

[0109] (4) Tuning using gain scheduling parameters The optimal control inputs for the control systems of vertical vibration, roll vibration, and pitch vibration are expressed by equations 11, 20, and 27. In this case, B T p, B roll T p roll , B pitch T p pitch The theoretical maximum value (maximum control amount) and minimum value (minimum control amount) of are calculated in advance. For example, B roll T p roll , B pitch T p pitch An example of the maximum and minimum values ​​of B is shown below. T Similarly, p can be calculated in advance.

[0110]

[0111]

[0112] The value between this maximum value and the longest value is used as the parameter (heave GSP, roll GSP). r , Pitch GSP p ) and linearly interpolate to select the desired control amount. r , Pitch GSP p Based on the control amount calculated using the formulas (11), (20), and (27), the target damping forces for vertical vibration suppression, roll vibration suppression, and pitch vibration suppression can be calculated.

[0113] When tuning BLQ without using gain scheduling parameters, Q, R, Q roll , R roll , Q pitch , R pitch It is necessary to change the gain scheduling parameters (heave GSP, roll GSP) and re-solve the Riccati equation each time. r , Pitch GSP p When tuning the BLQ using the above, there is no need to solve the Riccati equation again, and tuning can be performed with a low number of steps.

[0114] The vehicle behavior control device 1 according to the first embodiment has the configuration described above. Next, a process for variably controlling the damping force characteristics of the variable damper 7 using the controller 11 will be described.

[0115] When the vehicle is traveling, specifications related to the traveling of the vehicle are input to the controller 11 via the CAN 9. Based on the CAN signals, a state estimation unit 12 of the controller 11 estimates the vehicle state, such as the sprung-unsprung relative velocity, the vehicle body absolute vertical velocity (sprung velocity), the unsprung-road relative velocity, the unsprung absolute vertical velocity (unsprung velocity), the roll rate, the roll angle, the pitch rate, and the pitch angle.

[0116] At this time, the BLQ controller 20 of the controller 11 receives the vehicle state calculated by the state estimation unit 12, the heave GSP and the roll GSP calculated by the GSP calculation unit 13, and the vehicle speed. r , Pitch GSP pThe sprung vertical damping BLQ21 of the BLQ controller 20 calculates a heave target damping force based on the vehicle state and the heave GSP. The roll damping BLQ22 of the BLQ controller 20 calculates a heave target damping force based on the vehicle state and the roll GSP. r The pitch damping BLQ 23 of the BLQ controller 20 calculates the roll target damping force based on the vehicle state and the pitch GSP. p A heave target damping force is calculated based on the above.

[0117] The target damping force calculation unit 24 of the BLQ controller 20 calculates an actual target damping force based on the heave target damping force, the roll target damping force, and the pitch target damping force. The target damping coefficient calculation unit 27 of the BLQ controller 20 calculates the actual target damping force based on the relative velocity x * A minimum value selection unit 28 of the BLQ controller 20 selects the smaller value of the target damping coefficient C output from the target damping coefficient calculation unit 27 and the maximum damping coefficient Cmax output from the damping coefficient upper limit calculation unit 25, and outputs it as a corrected damping coefficient Ca. A command value calculation unit 29 of the BLQ controller 20 calculates the corrected damping coefficient Ca by dividing the corrected damping coefficient Ca by the relative speed x * A command current value I is calculated according to the above.

[0118] The command current value I is then input to the variable damping force actuator 8 of the variable damper 7, controlling the drive of the variable damping force actuator 8. As a result, the damping force characteristics of the variable damper 7 are continuously variable and controlled between hard characteristics and soft characteristics.

[0119] In particular, the controller 11 of the first embodiment is provided with the pitch vibration damping BLQ 23 and calculates the command current value I based on the pitch target damping force calculated by the pitch vibration damping BLQ 23. Therefore, pitch vibration can be suppressed more effectively than when the pitch vibration damping BLQ 23 is omitted.

[0120] In order to confirm the pitch vibration improvement effect of this embodiment, an actual vehicle test was conducted on the first embodiment and the comparative example when the vehicle was traveling on an undulating road. The results are shown in FIG. 15. In the actual vehicle test, the vehicle speed was 100 km / h, the heave GSP was 0.6, and the pitch GSP was 0.6.p was set to 0.3.

[0121] In FIG. 15 , the solid line indicates the characteristics according to the first embodiment. However, when calculating the target roll damping force, the controller 11 sets the gain of this target roll damping force to 0. That is, the solid line in FIG. 15 indicates the characteristics when the roll vibration suppression BLQ 22 is omitted from the controller 11 of the first embodiment. On the other hand, in FIG. 15 , the dashed line indicates the characteristics according to a comparative example (prior art). Here, the comparative example corresponds to the case where the controller according to Patent Document 1 is used. That is, in the comparative example, the variable damper 7 is controlled based on a target damping force that suppresses only the sprung vertical vibration. As shown in FIG. 15 , in the first embodiment, the amplitude of the pitch angle is reduced compared to the comparative example, and it can be seen that, for example, pitch vibration is improved (reduced) by about 7.3%.

[0122] Thus, the controller 11 as a control device according to this embodiment uses weighting coefficients (heave GSP, pitch GSP) that make the actual target damping force based on the calculated value of the vehicle behavior calculation unit (state estimation unit 12) approach a value close to the target damping force calculated in advance. p a weighting coefficient calculation unit (GSP calculation unit 13) that calculates a state related to the vertical movement of the vehicle (state estimation unit 12); a pitch movement calculation unit (state estimation unit 12) that calculates a state related to the movement of the vehicle in the pitch direction; an actual target damping force calculation unit (sprung vertical vibration damping BLQ21, pitch vibration damping BLQ23, target damping force calculation unit 24) that calculates the actual target damping force based on the weighting coefficients calculated by the weighting coefficient calculation unit, the vertical movement calculation unit, and the calculation results of the pitch movement calculation unit; a target damping coefficient calculation unit (target damping coefficient calculation unit 27) that calculates a target damping coefficient based on the calculation value of the actual target damping force calculation unit; and a relative velocity x between the sprung and unsprung parts of the vehicle. * The control signal output unit (command value calculation unit 29) outputs a control signal corresponding to the corrected damping coefficient Ca to the damping force adjustable shock absorber (variable damper 7).

[0123] At this time, the weighting coefficient calculation unit (GSP calculation unit 13) calculates, as weighting coefficients, a heave GSP related to the vertical movement of the vehicle and a pitch GSP related to the pitch movement of the vehicle. p The actual target damping force calculation unit calculates a target damping force in the vertical direction of the vehicle based on the heave GSP and the calculation result of the vertical movement calculation unit. p and a pitch BLQ (pitch vibration suppression BLQ23) that calculates a target damping force in the pitch direction of the vehicle based on the calculation results of the pitch movement calculation unit and the pitch movement calculation unit, and calculates the actual target damping force based on the target damping force (heave target damping force) calculated by the heave BLQ and the target damping force (pitch target damping force) calculated by the pitch BLQ.

[0124] Therefore, the controller 11 can control the damping force of the variable damper 7 based on the heave target damping force for suppressing the vertical vibration of the sprung mass and the pitch target damping force for suppressing the pitch vibration. As a result, it is possible to reduce both the vertical vibration of the sprung mass and the pitch vibration. In addition, the controller 11 can control the damping force of the variable damper 7 based on the weighting coefficients (heave GSP, pitch GSP) p ) and the vehicle state (relative velocity between sprung and unsprung masses, absolute vertical velocity of vehicle body (sprung velocity), relative velocity between unsprung mass and road surface, absolute vertical velocity of unsprung mass (unsprung velocity), pitch rate, pitch angle). Therefore, it is not necessary to solve the Riccati equation again, and the weighting coefficients (heave GSP, pitch GSP p ), tuning parameters can be reduced, and the controller 11 (sprung vertical vibration damping BLQ21, pitch vibration damping BLQ23) can be easily tuned.

[0125] The correction unit (minimum value selection unit 28) of the controller 11 calculates the correction damping coefficient Ca by multiplying the relative velocity x * The damping force increases as the relative velocity x * When the relative velocity x * The slope of the damping force with respect to the relative velocity x is small. *is set so that the slope of the damping force with respect to the relative velocity becomes large when the relative velocity x is high, and the correction unit * When the target damping coefficient C exceeds the maximum damping coefficient Cmax, the target damping coefficient C is corrected to the maximum damping coefficient Cmax and a corrected damping coefficient Ca is output.

[0126] Therefore, when the variable damper 7 reverses its stroke between the extension stroke and the retraction stroke, the relative velocity x * When the vehicle speed is low, the controller 11 outputs a corrected damping coefficient Ca that is obtained by lowering the upper limit of the target damping coefficient C, and outputs a command current value I that corresponds to this corrected damping coefficient Ca to the variable damper 7. This makes it possible to reduce the occurrence of abnormal noise and jerks that are caused by sudden changes in the damping force.

[0127] On the other hand, the controller 11 calculates the relative velocity x * When the relative speed x is high, the corrected damping coefficient Ca is calculated by increasing the upper limit of the target damping coefficient C compared to when the relative speed x is low. In this case, * When the relative speed x is high, it is possible to calculate a large corrected damping coefficient Ca without restricting the target damping coefficient C as much as possible. * When the vehicle is traveling at high speed, a large damping force is generated by the variable damper 7, thereby ensuring vibration damping and improving ride comfort.

[0128] The controller 11 further includes an attitude change detection unit (state estimation unit 12) that detects attitude changes of the vehicle body 2, and the correction unit (minimum value selection unit 28) reduces the amount of correction when it determines that an attitude change will occur based on the detection result of the attitude change detection unit.

[0129] At this time, when no change in the posture of the vehicle body 2 occurs, the correction unit increases the correction amount and lowers the upper limit of the target damping coefficient when the relative speed is low. This makes it possible to suppress sudden changes in the damping force. On the other hand, when a change in the posture of the vehicle body occurs, the correction unit decreases the correction amount and relaxes the upper limit of the target damping coefficient. This makes it possible to generate a damping force that resists the change in posture of the vehicle body, and ensures vibration control performance.

[0130] The controller 11 further includes a roll motion calculation unit (state estimation unit 12) that calculates a state related to the roll motion of the vehicle. In this case, the weighting coefficient calculation unit (GSP calculation unit 13) calculates the weighting coefficients based on the heave GSP related to the vertical motion of the vehicle and the roll GSP related to the roll motion of the vehicle. r and pitch GSP relating to the pitch direction motion of the vehicle p The actual target damping force calculation unit calculates a target damping force in the vertical direction of the vehicle based on the heave GSP and the calculation result of the vertical movement calculation unit. r and a roll BLQ (roll damping BLQ22) that calculates a target damping force in the roll direction of the vehicle based on the calculation result of the roll motion calculation unit. p and a pitch BLQ (pitch vibration suppression BLQ23) that calculates a target damping force in the pitch direction of the vehicle based on the calculation results of the pitch movement calculation unit and the pitch movement calculation unit, and calculates the actual target damping force based on the target damping force (heave target damping force) calculated by the heave BLQ, the target damping force (roll target damping force) calculated by the roll BLQ, and the target damping force (pitch target damping force) calculated by the pitch BLQ.

[0131] Therefore, the actual target damping force calculation units (sprung mass vertical vibration damping BLQ21, roll vibration damping BLQ22, pitch vibration damping BLQ23, target damping force calculation unit 24) can calculate the actual target damping force based on the calculation results of the roll motion calculation unit in addition to the calculation results of the vertical motion calculation unit and the pitch motion calculation unit. That is, the controller 11 can control the damping force of the variable damper 7 based on the heave target damping force for suppressing vertical vibration of the sprung mass, the pitch target damping force for suppressing pitch vibration, and the roll target damping force for suppressing roll vibration. As a result, roll vibration can be reduced in addition to the vertical vibration and pitch vibration of the sprung mass.

[0132] In the first embodiment, the controller 11 uses weighting factors (heave GSP, roll GSP r , Pitch GSP p) and the vehicle state (relative velocity between sprung and unsprung mass, absolute vertical velocity of vehicle body (sprung velocity), relative velocity between unsprung mass and road surface, absolute vertical velocity of unsprung mass (unsprung velocity), roll rate, roll angle, pitch rate, pitch angle). Therefore, it is not necessary to solve the Riccati equation again, and the weighting coefficients (heave GSP, roll GSP r , Pitch GSP p ), tuning parameters can be reduced, and the controller 11 (sprung vertical vibration damping BLQ21, roll vibration damping BLQ22, pitch vibration damping BLQ23) can be easily tuned.

[0133] Next, Figures 1, 2, 16 and 17 show a second embodiment. The second embodiment is characterized in that the weighting coefficient calculation unit changes the coefficients in accordance with the road surface condition, the vehicle weight and the selected damping force mode. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted.

[0134] The controller 31 according to the second embodiment constitutes a control device for the variable damper 7 and controls the damping characteristics of the variable damper 7 (see FIGS. 1 and 2). The controller 31 is configured in substantially the same manner as the controller 11 according to the first embodiment. The controller 31 is configured, for example, by a microcomputer and is connected to the CAN 9. The controller 31 acquires specifications related to the running of the vehicle through the CAN 9. The output side of the controller 31 is connected to the damping force variable actuator 8 of the variable damper 7.

[0135] The controller 31 also has a storage unit 31A including a ROM, a RAM, a non-volatile memory, etc. The storage unit 31A of the controller 31 stores various programs, information (vehicle information), data, etc. for controlling the variable damper 7.

[0136] 16, the controller 31 includes a state estimation unit 12, a GSP calculation unit 34, and a BLQ controller 20. In addition, the controller 31 includes a road surface index calculation unit 32 and a weight estimation unit 33.

[0137] The road surface index calculation unit 32 acquires, for example, the sprung velocity and the like from the state estimation unit 12, and outputs a road surface index using these. The road surface index calculation unit 32 estimates the vertical acceleration of the vehicle body 2 (sprung mass) from the sprung velocity and the like. The road surface index calculation unit 32 includes, for example, a band-pass filter, and extracts an undulating road component in a predetermined frequency band (e.g., 0.5 to 2 Hz) from the sprung mass vertical acceleration. The road surface index calculation unit 32 outputs a road surface index (undulating road index) corresponding to the magnitude of the undulating road component (undulating road level) to the GSP calculation unit 34. At this time, if the undulating road component is not extracted and is at its minimum value, the road surface index corresponding to the undulating road is 0. On the other hand, if the undulating road component is at its maximum value, the road surface index corresponding to the undulating road is 1. In this way, the road surface index is a normalized value between 0 and 1. That is, the road surface index is an index of 0 to 1 representing the up / down, pitch and roll movements (0.5 to 2 Hz) of the vehicle body 2 due to road surface input.

[0138] The road surface index calculation unit 32 is not limited to acquiring the sprung speed and the like from the state estimation unit 12, but may also acquire detection values ​​from a vertical acceleration sensor to calculate the road surface index. The road surface index calculation unit 32 may also acquire road surface information in the vehicle's traveling direction from a camera or the like to calculate the road surface index.

[0139] The weight estimation unit 33 acquires the absolute vertical displacement of the vehicle body 2, for example, based on a CAN signal. The weight estimation unit 33 estimates the weight of the vehicle body 2 based on the absolute vertical displacement of the vehicle body 2, and outputs the estimated weight to the GSP calculation unit 34. Note that the weight estimation unit 33 is not limited to estimating the weight of the vehicle body 2 from the absolute vertical displacement of the vehicle body 2, and may estimate the weight of the vehicle body 2 based on, for example, a signal from a stroke sensor that detects the stroke of the variable damper 7. The weight estimation unit 33 may obtain the weight of the vehicle body 2 by acquiring a detection value from a weight sensor that detects the weight of the vehicle body.

[0140] The GSP calculation unit 34 (gain scheduling parameter calculation unit) constitutes a weighting coefficient calculation unit that calculates a weighting coefficient that brings the actual target damping force based on the calculated value of the state estimation unit 12 (vehicle behavior calculation unit) closer to a predetermined target damping force. The GSP calculation unit 34 receives, for example, the vehicle speed acquired from the CAN 9, the road surface index from the road surface index calculation unit 32, and the estimated weight from the weight estimation unit 33. In addition, the GSP calculation unit 34 receives a car mode as a damping force mode. In this case, the car mode includes, for example, three types of modes: a normal mode (Normal), a sports mode (Sport), and a comfort mode (Comfort). The car mode is selected, for example, by a mode selection switch (not shown) provided on the vehicle. The GSP calculation unit 34 calculates heave GSP, roll GSP, and other parameters based on the vehicle speed, road surface index, weight estimation unit, and car mode. r , Pitch GSP p The car mode is not limited to three modes, but may have two modes, or may have four or more modes.

[0141] That is, when the BLQ controller 20 calculates an actual target damping force based on the vehicle state (for example, sprung-unsprung relative velocity, vehicle body absolute vertical velocity, unsprung-road relative velocity, unsprung absolute vertical velocity, roll rate, roll angle, pitch rate, pitch angle, etc.) calculated by the state estimation unit 12 (vehicle behavior calculation unit), the GSP calculation unit 34 calculates a weighting coefficient (heave GSP, roll GSP) that brings the actual target damping force closer to a value close to a target damping force calculated in advance. r , Pitch GSP p The GSP calculation unit 34 calculates the heave GSP, the roll GSP, r , Pitch GSP p is output to the BLQ controller 20.

[0142] As shown in FIG. 17, the GPS calculation unit 34 calculates, for example, the vehicle speed, the road surface index, the estimated weight, the car mode, the heave GPS, and the roll GPS. r , Pitch GSP p At this time, the heave GSP, roll GSP, and r , Pitch GSP pis determined by tuning in an actual vehicle test. Specifically, the heave GSP is finely adjusted by referring to vibration data, etc. after the rough characteristics are determined by subjective evaluation in an actual vehicle test. The GSP calculation unit 34 also includes a lookup table that records the relationship between the vehicle speed, road surface index, estimated weight, car mode and roll GSP, and a lookup table that records the relationship between the vehicle speed, road surface index, estimated weight, car mode and pitch GSP. Roll GSP r , Pitch GSP p Like the heave GSP, this is determined by tuning in actual vehicle tests.

[0143] As shown in FIG. 17 , for example, the GSP calculation unit 34 calculates a small value of heave GSP at low speeds and a large value of heave GSP at high speeds. When the GSP calculation unit 34 determines that the road is an undulating road based on the road surface index, it increases the value of the heave GSP. When the estimated weight is large, the GSP calculation unit 34 increases the value of the heave GSP compared to when the estimated weight is small. When the car mode is the sports mode, the GSP calculation unit 34 increases the value of the heave GSP compared to when the car mode is the normal mode. When the car mode is the comfort mode, the GSP calculation unit 34 decreases the value of the heave GSP compared to when the car mode is the normal mode. As with the heave GSP, the GSP calculation unit 34 calculates a roll GSP according to the vehicle speed, road surface index, estimated weight, and car mode. r , Pitch GSP p Calculate.

[0144] 17, the GSP calculation unit 34 is provided with three types of lookup tables corresponding to the road surface index, the estimated weight, and the car mode. The GSP calculation unit 34 calculates the heave GSP, the roll GSP, and the like, taking into consideration these three types of lookup tables. r , Pitch GSP p The present invention is not limited to this, and the GSP calculation unit 34 may calculate the heave GSP, roll GSP, and the like based on a single lookup table that combines the three types of lookup tables in FIG. r , Pitch GSP p may be calculated.

[0145] Thus, the second embodiment can also achieve substantially the same effects as the first embodiment. In the second embodiment, the weighting coefficient calculation unit (GSP calculation unit 34) changes the coefficient in accordance with the road surface condition. Therefore, the actual target damping force can be changed in accordance with the road surface condition, thereby improving ride comfort and vehicle stability. The weighting coefficient calculation unit (GSP calculation unit 34) changes the coefficient in accordance with the weight of the vehicle body 2. Therefore, the actual target damping force can be changed in accordance with the weight of the vehicle body 2, thereby improving ride comfort and vehicle stability. The weighting coefficient calculation unit (GSP calculation unit 34) changes the coefficient in accordance with the selected damping force mode (car mode). Therefore, the actual target damping force can be changed in accordance with the selected car mode, thereby improving ride comfort and vehicle stability.

[0146] In the second embodiment, the GSP calculation unit 34 calculates weighting coefficients (heave GSP, roll GSP) based on the road surface index, estimated weight, and car mode. r , Pitch GSP p ), but the present invention is not limited to this. The GSP calculation unit 34 calculates weighting coefficients (heave GSP, roll GSP) based on one or two of the road surface index, estimated weight, and car mode. r , Pitch GSP p ) may be calculated.

[0147] In the second embodiment, the road surface index is an undulating road index, but the present invention is not limited to this. The road surface index may be an index corresponding to the state of a road surface other than an undulating road, such as a rough road.

[0148] 1, 2, 18 to 22 show a third embodiment. The third embodiment is characterized in that the weighting coefficient calculation unit changes the coefficients in accordance with the vehicle body weight and the front-rear weight balance determined in advance. In the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and their description will be omitted.

[0149] The controller 41 according to the third embodiment constitutes a control device for the variable damper 7 and controls the damping characteristics of the variable damper 7 (see FIGS. 1 and 2). The controller 41 is configured in substantially the same manner as the controller 11 according to the first embodiment. The controller 41 is configured, for example, by a microcomputer and is connected to the CAN 9. The controller 41 acquires specifications related to the running of the vehicle through the CAN 9. The output side of the controller 41 is connected to the damping force variable actuator 8 of the variable damper 7.

[0150] The controller 41 also has a storage unit 41A including a ROM, a RAM, a non-volatile memory, etc. The storage unit 41A of the controller 41 stores various programs, information (vehicle information), data, etc. for controlling the variable damper 7.

[0151] 18, the controller 41 includes a state estimation unit 12, a GSP calculation unit 34, and a BLQ controller 42. In addition, the controller 31 includes a road surface index calculation unit 32 and a weight estimation unit 33.

[0152] The BLQ controller 42 calculates a command current (control signal) that serves as a command value based on bilinear optimal control theory. The BLQ controller 42 is configured in the same manner as the BLQ controller 20 according to the first embodiment. In this case, as shown in Fig. 19 , the BLQ controller 42 includes a sprung vertical vibration damping BLQ 43, a roll vibration damping BLQ 44, a pitch vibration damping BLQ 45, a target damping force calculation unit 24, a damping coefficient upper limit calculation unit 25, a corrected damping coefficient calculation unit 26, and a command value calculation unit 29.

[0153] The sprung vertical vibration damping BLQ43 is configured in the same manner as the sprung vertical vibration damping BLQ21 according to the first embodiment. The sprung vertical vibration damping BLQ43 receives as input the vehicle state output from the state estimation unit 12, the heave GSP output from the GSP calculation unit 34, and the estimated weight output from the weight estimation unit 33. The sprung vertical vibration damping BLQ43 calculates the heave target damping force of the variable damper 7 for reducing vertical vibration, separately for the front wheels and the rear wheels, based on the sprung-unsprung relative velocity, vehicle body absolute vertical velocity, unsprung-road relative velocity, and unsprung absolute vertical velocity output from the state estimation unit 12, the heave GSP output from the GSP calculation unit 34, and the estimated weight output from the weight estimation unit 33.

[0154] As shown in FIG. 20 , the sprung vertical vibration damping BLQ 43 includes a correction gain calculation unit 43A, a Bp calculation unit 43B, a multiplier 43C, a Bp calculation unit 43D, a multiplier 43E, a multiplier 43F, and a heave target damping force calculation unit 43G. The correction gain calculation unit 43A calculates a correction gain for the front wheels and a correction gain for the rear wheels based on the estimated weight. The Bp calculation unit 43B calculates the maximum value of Bp according to the relative speed based on the previously calculated Bp and heave GSP. The multiplier 43C multiplies the correction gain output from the correction gain calculation unit 43A by the maximum value of Bp output from the Bp calculation unit 43B and the relative speed. The Bp calculation unit 43D calculates the maximum value of Bp according to the sprung speed based on the previously calculated Bp and heave GSP. The multiplier 43E multiplies the correction gain output from the correction gain calculation unit 43A by the maximum value of Bp output from the Bp calculation unit 43D and the sprung velocity. The multiplier 43F multiplies the value calculated by the multiplier 43C by the value calculated by the multiplier 43E. The heave target damping force calculation unit 43G multiplies the value calculated by the multiplier 43F by the inverse matrix of R (R -1 ) to calculate the target heave damping force for the front wheels and the target heave damping force for the rear wheels. Note that, although the sprung vertical damping BLQ43 has calculated the target heave damping force based on Bp according to the relative speed and Bp according to the sprung speed, the present invention is not limited to this. The sprung vertical damping BLQ43 may calculate the target heave damping force based on Bp according to other vehicle conditions in addition to Bp according to the relative speed and sprung speed.

[0155] The roll vibration damping BLQ 44 is based on the vehicle state output from the state estimation unit 12 and the roll GSP output from the GSP calculation unit 34. r and the estimated weight output from the weight estimation unit 33. The roll vibration suppression BLQ 22 calculates the target roll damping forces of the variable damper 7 for reducing roll vibration separately for the front wheels and the rear wheels, based on the roll rate and roll angle output from the state estimation unit 12, the roll GSP output from the GSP calculation unit 34, and the estimated weight output from the weight estimation unit 33.

[0156] As shown in Fig. 21, the roll vibration suppression BLQ 44 includes a correction gain calculation unit 44A, a Bp calculation unit 44B, multipliers 44C and 44D, and a roll target damping force calculation unit 44E. The correction gain calculation unit 44A calculates a correction gain for the front wheels and a correction gain for the rear wheels based on the estimated weight. The Bp calculation unit 44B calculates a correction gain for the front wheels and a correction gain for the rear wheels based on the estimated weight. roll p roll and Roll GSP r Based on this, B according to the roll rate roll p roll The multiplier 44C multiplies the correction gain output from the correction gain calculation unit 44A by the Bp calculation unit 44B. roll p roll The multiplier 44D multiplies the value calculated by the multiplier 44C by the roll rate. The roll target damping force calculation unit 44E multiplies the value calculated by the multiplier 44D by the previously calculated R roll The inverse matrix (R roll -1 ) to calculate the target roll damping force for the front wheels and the target roll damping force for the rear wheels.

[0157] The pitch vibration damping BLQ 45 is based on the vehicle state output from the state estimation unit 12 and the pitch GSP output from the GSP calculation unit 34. p and the estimated weight output from the weight estimation unit 33. The pitch vibration suppression BLQ 45 receives the pitch rate and pitch angle output from the state estimation unit 12 and the pitch GSP output from the GSP calculation unit 34. pBased on the above, the target pitch damping force of the variable damper 7 for reducing pitch vibration is calculated separately for the front wheels and the rear wheels.

[0158] As shown in Fig. 22, the pitch vibration suppression BLQ 45 includes a correction gain calculation unit 45A, a Bp calculation unit 45B, multipliers 45C and 45D, and a pitch target damping force calculation unit 45E. The correction gain calculation unit 45A calculates a correction gain for the front wheels and a correction gain for the rear wheels based on the estimated weight. The Bp calculation unit 45B calculates a correction gain for the front wheels and a correction gain for the rear wheels based on the estimated weight. pitch p pitch and Pitch GSP p Based on this, B according to the pitch rate pitch p pitch The multiplier 45C multiplies the correction gain output from the correction gain calculation unit 45A by the Bp calculation unit 45B. pitch p pitch The multiplier 45D multiplies the value calculated by the multiplier 45C by the pitch rate. The pitch target damping force calculation unit 45E multiplies the value calculated by the multiplier 45D by the previously calculated R pitch The inverse matrix (R pitch -1 ) to calculate the pitch target damping force for the front wheels and the pitch target damping force for the rear wheels.

[0159] In this case, the GSP calculation unit 34 and the correction gain calculation units 43A, 44A, and 45A constitute a weighting coefficient calculation unit.

[0160] Thus, the third embodiment can achieve substantially the same effects as the first and second embodiments. In the third embodiment, the weighting coefficient calculation units (GSP calculation unit 34, correction gain calculation units 43A, 44A, 45A) change coefficients based on the previously determined front-to-rear weight balance of the vehicle body 2 and the weight of the vehicle body 2. Specifically, the heave BLQ (sprung vertical damping BLQ 21), roll BLQ (roll damping BLQ 22), and pitch BLQ (pitch damping BLQ 23) calculate the heave target damping force, roll target damping force, and pitch target damping force, taking the front-to-rear weight balance of the vehicle body into consideration. This allows the ratio between the front-wheel target damping force and the rear-wheel target damping force to be adjusted based on the vehicle weight. As a result, ride comfort and other factors can be improved even when the ride comfort and vehicle stability change depending on the number of passengers, payload, and other factors.

[0161] In the third embodiment, the controller 41 includes the GSP calculation unit 34 of the second embodiment, but may also include the GSP calculation unit 13 of the first embodiment. Also, in the third embodiment, the weighting coefficient calculation unit is configured by the GSP calculation unit 34 and the correction gain calculation units 43A, 44A, and 45A. However, the present invention is not limited to this, and the GSP calculation unit 34 and the correction gain calculation units 43A, 44A, and 45A may be integrated to form a lookup table, and the weighting coefficient calculation unit may be configured by this lookup table.

[0162] 4 and 17 show examples of lookup tables constituting the GSP calculation units 13 and 34, Fig. 6 shows an example of the damping coefficient upper limit calculation unit 25, and Fig. 7 shows an example of the command value calculation unit 29, but the present invention is not limited to these. The GSP calculation unit, the damping coefficient upper limit calculation unit, and the command value calculation unit are set appropriately in consideration of the vehicle specifications and the like.

[0163] In the above-described embodiments, the controllers 11, 31, and 41 acquire vehicle driving parameters via the CAN 9. However, the present invention is not limited to this. The controllers 11, 31, and 41 may be connected to, for example, an acceleration sensor that detects the vertical acceleration of the sprung and unsprung parts, a wheel speed sensor that detects the wheel speed, or the like, and acquire the detected values ​​of these sensors as vehicle driving parameters. The controllers 11, 31, and 41 may also acquire vehicle driving parameters from another controller or the like.

[0164] In each of the above embodiments, the controller 11, 31, 41 includes a state estimator 12 including a vertical motion calculator, a roll motion calculator, and a pitch motion calculator. In this case, the state estimator 12 determines a state related to the vertical motion of the vehicle from the CAN signal, determines a state related to the roll motion of the vehicle from the CAN signal, and determines a state related to the pitch motion of the vehicle from the CAN signal. The present invention is not limited to this. For example, the controller 11, 31, 41 may be connected to a vertical acceleration sensor, a roll sensor, a pitch sensor, etc., and calculate the state related to the vertical motion of the vehicle, the state related to the roll motion of the vehicle, and the state related to the pitch motion of the vehicle based on the detection values ​​of these sensors. In this case, the parts of the controller 11, 31, 41 that calculate the respective states constitute the vertical motion calculator, the roll motion calculator, and the pitch motion calculator, respectively.

[0165] In the above-described embodiments, the damping force adjustable shock absorber is described as an example in which the variable damper 7 is a semi-active damper. However, the present invention is not limited to this, and an active damper (either an electric actuator or a hydraulic actuator) may be used as the damping force adjustable shock absorber. In the above-described embodiments, the damping force adjustable shock absorber that generates an adjustable force between the vehicle body 2 side and the wheel 3 side is described as an example in which the variable damper 7 is a hydraulic shock absorber. However, the present invention is not limited to this, and the damping force adjustable shock absorber may be configured as an air suspension, an electromagnetic suspension, or the like, in addition to a hydraulic shock absorber.

[0166] In the above embodiments, the vehicle behavior control device is used for a four-wheeled vehicle. However, the present invention is not limited to this and can also be applied to, for example, two-wheeled or three-wheeled vehicles, or work vehicles, transport vehicles such as trucks and buses.

[0167] The specific numerical values ​​described in each of the above embodiments are merely examples and are not limited to the exemplified values. Furthermore, it goes without saying that each of the above embodiments is merely an example, and partial substitution or combination of the configurations shown in different embodiments is possible.

[0168] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0169] This application claims priority to Japanese Patent Application No. 2022-207940, filed December 26, 2022. The entire disclosure of Japanese Patent Application No. 2022-207940, filed December 26, 2022, including the specification, claims, drawings, and abstract, is incorporated herein by reference in its entirety.

[0170] 1: Vehicle behavior control device, 2: Vehicle body, 3: Wheel, 5: Suspension device, 7: Adjustable damping force shock absorber (variable damper), 8: Variable damping force actuator, 9: CAN, 11, 31, 41: Controller (control device), 12: State estimation unit (vehicle behavior calculation unit, vertical movement calculation unit, roll movement calculation unit, pitch movement calculation unit, attitude change detection unit), 13, 34: GPS calculation unit (weighting coefficient calculation unit), 20, 42: BLQ controller, 21, 43: Spring vertical vibration damping BLQ (heave BLQ), 22, 44: roll vibration damping BLQ (roll BLQ), 23, 45: pitch vibration damping BLQ (pitch BLQ), 24: target damping force calculation unit (actual target damping force calculation unit), 25: damping coefficient upper limit calculation unit, 26: corrected damping coefficient calculation unit, 27: target damping coefficient calculation unit (target damping coefficient calculation unit), 28: minimum value selection unit (correction unit), 29: command value calculation unit (control signal output unit), 32: road surface index calculation unit, 33: weight estimation unit

Claims

1. A control device for a damping force adjustable shock absorber that is provided in a vehicle and is capable of adjusting a generated damping force, a weighting coefficient calculation unit that calculates a weighting coefficient for making the actual target damping force closer to a predetermined target damping force when calculating an actual target damping force based on a calculated value of the vehicle behavior calculation unit; A vertical motion calculation unit that calculates a vertical motion state of the vehicle; a pitch motion calculation unit that calculates a motion state in a pitch direction of the vehicle; an actual target damping force calculation unit that calculates the actual target damping force based on the weighting coefficient calculated by the weighting coefficient calculation unit and the calculation results of the vertical movement calculation unit and the pitch movement calculation unit; a target damping coefficient calculation unit that calculates a target damping coefficient based on the calculated value of the actual target damping force calculation unit; a correction unit that calculates a corrected damping coefficient by lowering an upper limit of the target damping coefficient in a region where a relative speed between a sprung portion and an unsprung portion of the vehicle is lower than a predetermined value; a control signal output unit that outputs a control signal corresponding to the corrected damping coefficient to the damping force adjustable shock absorber, the correction unit sets the corrected damping coefficient so that the damping force increases as the relative velocity increases, and so that when the relative velocity is slower than the predetermined value, a slope of the damping force with respect to the relative velocity is small, and when the relative velocity is faster than the predetermined value, a slope of the damping force with respect to the relative velocity is large, the correction unit has a maximum damping coefficient according to the relative speed, and when the target damping coefficient exceeds the maximum damping coefficient, corrects the target damping coefficient to the maximum damping coefficient; The weighting factor calculation unit changes the weighting factor depending on a road surface condition. Control device.

2. The control device according to claim 1 , Further comprising a posture change detection unit for detecting a posture change of the vehicle body, The correction unit reduces an amount of correction when it determines that a posture change will occur based on a detection result from the posture change detection unit.

3. The control device according to claim 1 , The control device further includes a roll motion calculation unit that determines a motion state in a roll direction of the vehicle.

4. The control device according to claim 1 , The weighting coefficient calculation unit changes the weighting coefficient according to a weight of a vehicle body.

5. The control device according to claim 1 , The weighting coefficient calculation unit changes the weighting coefficient depending on a selected damping force mode.

6. The control device according to claim 1 , The weighting coefficient calculation unit changes the weighting coefficient according to a predetermined front-rear weight balance of the vehicle body and the weight of the vehicle body.

7. The control device according to claim 1 , The weighting coefficient calculation unit calculates, as the weighting coefficient, a heave GSP related to a vertical movement of the vehicle and a pitch GSP related to a pitch movement of the vehicle, The actual target damping force calculation unit includes a heave BLQ that calculates a target damping force in the vertical direction of the vehicle based on the heave GSP and the calculation result of the vertical movement calculation unit, and a pitch BLQ that calculates a target damping force in the pitch direction of the vehicle based on the pitch GSP and the calculation result of the pitch movement calculation unit, A control device wherein the actual target damping force calculation unit calculates the actual target damping force based on the target damping force calculated by the heave BLQ and the target damping force calculated by the pitch BLQ.

8. The control device according to claim 3, the weighting coefficient calculation unit calculates, as the weighting coefficients, a heave GSP related to a vertical motion of the vehicle, a roll GSP related to a roll direction motion of the vehicle, and a pitch GSP related to a pitch direction motion of the vehicle; The actual target damping force calculation unit includes a heave BLQ that calculates a target damping force in the vertical direction of the vehicle based on the heave GSP and the calculation result of the vertical movement calculation unit, a roll BLQ that calculates a target damping force in the roll direction of the vehicle based on the roll GSP and the calculation result of the roll movement calculation unit, and a pitch BLQ that calculates a target damping force in the pitch direction of the vehicle based on the pitch GSP and the calculation result of the pitch movement calculation unit, A control device wherein the actual target damping force calculation unit calculates the actual target damping force based on the target damping force calculated by the heave BLQ, the target damping force calculated by the roll BLQ, and the target damping force calculated by the pitch BLQ.

9. The control device according to claim 8, A control device that calculates target damping forces for the heave BLQ, the roll BLQ and the pitch BLQ by taking into account the front and rear weight balance of a vehicle body.