Vehicle control system

Abstract

To provide a vehicle control system and a vehicle control device that can enhance stability of a vehicle by reducing ground contact load fluctuations.SOLUTION: A vehicle control system includes a plurality of variable dampers 6 which are each provided between a vehicle body 1 and four wheels 2 of a vehicle and whose generated force can be adjusted between soft and hard, and an ECU 21 which variably controls the generated force of the variable dampers 6. When a signal from a drive / brake determination unit 31 that independently drives and brakes the four wheels 2 is input, the ECU 21 adjusts the generated force of the variable dampers 6 so that ground contact load fluctuations on the road surface caused by the variable dampers 6 become small.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a vehicle control system and a vehicle control device that control an actuator that varies the force for suppressing the relative displacement between a vehicle body and wheels.

Background Art

[0002] The control device disclosed in Patent Document 1 executes either a compression stroke hard-soft switching control that switches the damping force characteristics of a damper provided on the wheel side that increases the wheel load, with the initial stage during the compression stroke being on the hard side and the latter stage being on the soft side, or an extension stroke soft-hard switching control that switches the initial stage during the extension stroke to the soft side and the latter stage to the hard side. Thereby, the responsiveness and the absolute amount of increase and decrease in the wheel load can be controlled, and the vehicle can be more safely controlled.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the control device disclosed in Patent Document 1 executes either compression stroke hard-soft switching control or extension stroke soft-hard switching control. However, when such control is performed, the ground load fluctuation tends to increase, and for example, when an operation such as ABS (Anti-lock Breake System) is performed, the stability of the vehicle may decrease.

[0005] An object of an embodiment of the present invention is to provide a vehicle control system that can reduce ground load fluctuation and enhance the stability of a vehicle. <( Mu

Means for Solving the Problems

[0006] J The vehicle comprises a plurality of force generating mechanisms, each provided between the vehicle body and the four wheels, with a force generation force adjustable between soft and hard, and control means for variably controlling the force generated by the force generating mechanisms, wherein the control means includes an unsprung vibration control unit that outputs an unsprung vibration control command value for suppressing unsprung vibration based on signals from a braking / driving determination unit that independently brakes and drives the four wheels and signals of relative acceleration between the vehicle body and the wheels, and adjusts the force generated by the force generating mechanisms so that the fluctuation of the contact load on the road surface by the force generating mechanisms is reduced based on the unsprung vibration control command value.A vehicle control system according to one embodiment of the present invention is The vehicle comprises a plurality of force generating mechanisms, each provided between the vehicle body and the four wheels, with a force generation force adjustable between soft and hard, and control means for variably controlling the force generated by the force generating mechanisms, wherein the control means includes an unsprung vibration control unit that outputs an unsprung vibration control command value for suppressing unsprung vibration based on signals from a braking / driving determination unit that independently brakes and drives the four wheels and signals of relative acceleration between the vehicle body and the wheels, and adjusts the force generated by the force generating mechanisms so that the fluctuation of the contact load on the road surface by the force generating mechanisms is reduced based on the unsprung vibration control command value. It is characterized by the following. [Effects of the Invention]

[0008] According to one embodiment of the present invention, it is possible to reduce fluctuations in ground contact load and improve the stability of the vehicle. [Brief explanation of the drawing]

[0009] [Figure 1] This is an overall configuration diagram showing a four-wheeled vehicle to which an ECU according to an embodiment of the present invention is applied. [Figure 2] This diagram schematically shows a shock absorber installed in the automobile shown in Figure 1. [Figure 3] This is a block diagram showing the configuration of the ECU in the first embodiment. [Figure 4] This block diagram shows the configuration of the anti-dive squat control unit in Figure 3. [Figure 5] This block diagram shows the configuration of the anti-roll control unit in Figure 3. [Figure 6] The first embodiment and comparative examples are shown as characteristic diagrams illustrating the time variation of vehicle speed, longitudinal acceleration, pitch rate, pitch angle, and the current value supplied to the variable dampers of each wheel. [Figure 7] The first embodiment and comparative example are characteristic diagrams showing the time variation of the damping force generated by the variable damper of each wheel. [Figure 8] The following are characteristic diagrams showing the time variation of the wheel load of each wheel for the first embodiment and comparative example. [Figure 9] This block diagram shows the configuration of the ECU in the second embodiment. [Figure 10] This is an explanatory diagram showing the relationship between the current value supplied to the variable damper of the left front wheel and the RMS value of the wheel load fluctuation. [Figure 11] This is an explanatory diagram showing the relationship between the current value supplied to the variable damper of the left rear wheel and the RMS value of the wheel load fluctuation. [Figure 12] This is a characteristic curve showing the relationship between piston speed and damping force of the variable damper on the left front wheel. [Figure 13] It is a characteristic diagram showing the relationship between the piston speed and the damping force of the variable damper of the left rear wheel. [Figure 14] It is a block diagram showing the configuration of the ECU of the third embodiment. [Figure 15] It is a diagram schematically showing the state transition based on the relative acceleration between above the spring and below the spring. [Figure 16] It is a characteristic diagram showing the time change of the relative acceleration, the state, and the command value. [Figure 17] It is a block diagram showing the configuration of the ECU of the fourth embodiment.

Mode for Carrying Out the Invention

[0010] The present invention belongs to a group of inventions that encompasses multiple inventions described below. The first to third embodiments of this group of inventions will be described below, with the third embodiment corresponding to the invention described in the claims by the present applicant. Hereinafter, a vehicle control system and a vehicle control device according to an embodiment of the present invention will be described in detail according to the accompanying drawings, taking, for example, the case where they are applied to a four-wheel automobile.

[0011] Here, FIGS. 1 to 5 show the first embodiment of the present invention. In FIGS. 1 and 2, the vehicle body 1 constitutes the body of the vehicle. Below the vehicle body 1, for example, left and right front wheels and left and right rear wheels (hereinafter collectively referred to as wheels 2) are provided. These wheels 2 are configured to include tires 3. The tire 3 acts as a spring that absorbs fine irregularities on the road surface. The vehicle body 1 and the wheels 2 constitute a vehicle.

[0012] The suspension device 4 is provided interposed between the vehicle body 1 and the wheels 2. The suspension device 4 is composed of a suspension spring 5 (hereinafter referred to as spring 5) and a damping force adjustable shock absorber (hereinafter referred to as variable damper 6) provided interposed between the vehicle body 1 and the wheels 2 in a parallel relationship with the spring 5.

[0013] The variable dampers 6 of the suspension system 4 are provided between the vehicle body 1 and each of the four wheels 2. The variable damper 6 is an actuator that varies the force that suppresses the relative displacement between the vehicle body 1 and the wheels 2. The variable damper 6 varies the force generated between the vehicle body 1 and the wheels 2. The variable damper 6 is also a force generating mechanism that adjusts the force between the vehicle body 1 and the wheels 2. The force generated by the variable damper 6 can be adjusted between soft and hard.

[0014] The variable damper 6 is constructed using a damping force adjustable hydraulic shock absorber. As shown in Figure 2, the variable damper 6 is equipped with a damping force variable actuator 7, which consists of a damping force adjustment valve, etc., to continuously adjust the characteristics of the generated damping force (i.e., damping force characteristics) from hard characteristics (rigid characteristics) to soft characteristics (flexible characteristics). The damping force variable actuator 7 is a damping force adjustment unit in which the damping force is adjusted according to the supplied current (drive current).

[0015] Furthermore, the variable damping actuator 7 does not necessarily have to be configured to continuously adjust the damping force characteristics; for example, it may be capable of adjusting the damping force in two or more stages. Also, the variable damper 6 may be a pressure-controlled type or a flow-controlled type.

[0016] CAN8 (controller area network) is a serial communication unit mounted on the vehicle body 1. CAN8 performs in-vehicle-specific multiplex communication between numerous electronic devices mounted on the vehicle and the ECU 21. CAN8 transmits vehicle driving information via CAN signals, which consist of serial signals. In this case, the vehicle driving information transmitted by CAN8 includes, for example, yaw rate, steering angle, vehicle speed, longitudinal acceleration, brake fluid pressure, engine torque, etc.

[0017] In addition to this, the vehicle driving information transmitted via CAN8 also includes signals from the brake / drive determination unit 31. The brake / drive determination unit 31 independently brakes or drives the four wheels 2. The brake / drive determination unit 31 includes, for example, ABS, TCS (Traction Control System), and ECS (Electronic Stability Control). The signals from the brake / drive determination unit 31 are, for example, ABS / TCS / ECS operation flags indicating that one of ABS, TCS, or ECS has been activated.

[0018] The sprung mass acceleration sensor 9 is installed on the vehicle body 1 and detects vertical vibration acceleration on the vehicle body 1 side, which is the sprung mass side. The sprung mass acceleration sensor 9 constitutes a sprung mass state detection means that detects vibrations of the sprung mass. The sprung mass state detection means is not limited to detecting vibrations of the sprung mass, but may also estimate vibrations of the sprung mass based on vehicle driving information included in the CAN signal, for example.

[0019] For example, a total of three sprung mass acceleration sensors 9 are provided on the vehicle body 1. In this case, the sprung mass acceleration sensors 9 are attached to the vehicle body 1 at a position near the upper end of the variable dampers 6 on the left and right front wheels, and also at an intermediate position between the left and right rear wheels. The sprung mass acceleration sensors 9 detect vertical vibration acceleration on the sprung mass side of the vehicle body 1 and output the detection signal to the ECU 21.

[0020] The unsprung mass acceleration sensor 10 is installed on the wheel 2 side of the vehicle. A total of two unsprung mass acceleration sensors 10 are installed on the vehicle. Specifically, for example, the unsprung mass acceleration sensors 10 are installed on the right front wheel and the left front wheel of the vehicle. The unsprung mass acceleration sensor 10 detects vertical vibration acceleration on the wheel 2 side, which is the unsprung mass, and outputs the detection signal to the ECU 21.

[0021] The ECU21 constitutes a vehicle control device that controls the suspension system 4. The ECU21 controls the variable damper 6, which varies the force generated between the vehicle body 1 and the wheels 2. Here, the ECU21 is a control means that controls the force generated by the variable damper 6 (force generation mechanism).

[0022] The ECU21 includes a processor 22 as a control unit. The processor 22 is composed of a microcomputer or the like. The ECU21 also includes a storage unit (not shown) consisting of ROM, RAM, non-volatile memory, etc. The processor 22 controls the damping force of the variable damper 6 by executing a program stored in the storage unit.

[0023] As shown in Figure 2, the ECU 21 has its input side connected to CAN 8, sprung mass acceleration sensor 9, unsprung mass acceleration sensor 10, etc., and its output side connected to the variable damping force actuator 7 of the variable damper 6, etc. The processor 22 reads vehicle driving information from CAN 8 via serial communication. The processor 22 reads the sprung mass acceleration sensor value (sprung mass acceleration) from the detection signal from the sprung mass acceleration sensor 9. The processor 22 reads the unsprung mass acceleration sensor value (unsprung mass acceleration) from the detection signal from the unsprung mass acceleration sensor 10.

[0024] As shown in Figure 3, the ECU 21 includes an observer 23 that determines vehicle behavior such as relative velocity and relative acceleration between the sprung mass and unsprung mass. In addition, the ECU 21 includes a ride comfort control unit 24, a posture stability control unit 25, an ABS / TCS / ECS coordinated control unit 29, and a control command selection unit 30, which will be described later.

[0025] Observer 23 determines vehicle behavior based on the sprung mass acceleration input from the sprung mass acceleration sensor 9 and the unsprung mass acceleration input from the unsprung mass acceleration sensor 10. Observer 23 is equipped with a subtractor and an integrator (neither of which are shown). Observer 23 receives the sprung mass acceleration and unsprung mass acceleration as inputs. The subtractor subtracts the unsprung mass acceleration from the sprung mass acceleration to obtain the relative acceleration, which is the difference between them. The integrator integrates the sprung mass acceleration to obtain the sprung mass velocity. Another integrator integrates the relative acceleration to obtain the relative velocity. Observer 23 outputs the sprung mass velocity, relative velocity, and relative acceleration.

[0026] In the first embodiment, the observer 23 obtained relative velocity from sprung mass acceleration and unsprung mass acceleration. For example, if each wheel's suspension device 4 is equipped with a stroke sensor, relative velocity, relative acceleration, etc. may be obtained based on the detected values ​​of the stroke sensors. Alternatively, relative velocity, relative acceleration, etc. may be estimated based on information (vehicle driving information) input from CAN 8.

[0027] The ride comfort control unit 24 outputs ride comfort control commands to improve the ride comfort of the vehicle. The ride comfort control unit 24 outputs ride comfort control command values ​​to control the variable damper 6 in response to the input sprung mass vibration of the vehicle. Sprung mass vibration of the vehicle includes, for example, sprung mass velocity and relative velocity. Sprung mass vibration of the vehicle may be detected directly by sensors, etc., or may be estimated based on, for example, sprung mass acceleration. The ride comfort control unit 24 obtains sprung mass velocity and relative velocity (piston velocity) between the sprung mass and unsprung mass from the observer 23. The ride comfort control unit 24 outputs ride comfort control commands based on the sprung mass velocity and relative velocity of each wheel. At this time, the ride comfort control command is a control command value (current value) that becomes, for example, a command signal for current to the damping force variable actuator 7. The ride comfort control unit 24 outputs ride comfort control command values ​​to reduce vertical vibration of the sprung mass from the sprung mass velocity and relative velocity, for example, based on the skyhook control law.

[0028] In the first embodiment, the ride comfort control unit 24 outputs ride comfort control commands based on skyhook control. The present invention is not limited to this, and the ride comfort control unit may output ride comfort control commands based on, for example, bilinear optimal control or H∞ control.

[0029] The attitude stability control unit 25 outputs attitude stability control commands to improve the vehicle's attitude stability (handling stability). The attitude stability control unit 25 receives longitudinal acceleration and lateral acceleration transmitted from CAN8 as input. Based on the longitudinal acceleration and lateral acceleration, the attitude stability control unit 25 outputs attitude stability control commands. The attitude stability control unit 25 outputs attitude stability control command values ​​to control the variable damper 6 in accordance with the input vehicle attitude change.

[0030] The attitude stability control unit 25 outputs an attitude stability control command such that the variable damper 6 becomes hard when the change in the vehicle's attitude exceeds a predetermined value. Changes in the vehicle's attitude include, for example, turning, acceleration, and deceleration. In this case, the turning of the vehicle may be detected and estimated based on, for example, the steering angle and lateral acceleration. The acceleration or deceleration of the vehicle may be detected and estimated based on, for example, the brake fluid pressure and engine motor torque.

[0031] The attitude stability control unit 25 receives longitudinal and lateral acceleration as input. As shown in Figure 3, the attitude stability control unit 25 includes an anti-dive squat control unit 26, an anti-roll control unit 27, and a pre-control command selection unit 28.

[0032] The anti-dive squat control unit 26 outputs an anti-dive squat control command to suppress the longitudinal tilt of the vehicle due to acceleration or deceleration of the vehicle. The longitudinal acceleration is input to the anti-dive squat control unit 26. As shown in Figure 4, the anti-dive squat control unit 26 includes a differentiator 26A, a front gain multiplier 26B, an inversion unit 26C, a rear gain multiplier 26D, a relative velocity calculation unit 26E, and a damping force characteristic processing unit 26F.

[0033] The differentiator 26A calculates the longitudinal jerk of the vehicle by differentiating the longitudinal acceleration (longitudinal jerk). The front gain multiplier 26B multiplies the longitudinal jerk by the front gain and outputs the target damping force for the front. The rear gain multiplier 26D multiplies the longitudinal jerk, which has been multiplied by "-1" by the inversion unit 26C, by the rear gain and outputs the target damping force for the rear.

[0034] For example, if the derivative of the longitudinal acceleration (longitudinal jerk) is negative, dive behavior is predicted. Therefore, the front side needs to derive a target damping force to accommodate damper compression, and the rear side needs to derive a target damping force to accommodate damper extension. Taking this into consideration, the reversal section 26C multiplies the longitudinal jerk by "-1" before applying the rear gain. That is, here, the extension side of the damper is set to positive, and the compression side of the damper is set to negative.

[0035] The relative speed calculation unit 26E calculates the relative speed from the front and rear jerk accelerations. The damping force characteristic processing unit 26F is composed of a damping force map that shows, for example, the relationship between the target damping force and relative speed and the command value (control command) output to the variable damper 6. The damping force characteristic processing unit 26F outputs a control command to control the front variable damper 6 based on the target damping force and relative speed on the front side. The damping force characteristic processing unit 26F outputs a control command to control the rear variable damper 6 based on the target damping force and relative speed on the rear side. These control commands are anti-dive squat control commands and are, for example, control command values ​​(current values) that become command signals for the current to the damping force variable actuator 7.

[0036] The anti-roll control unit 27 outputs an anti-roll control command to suppress the roll behavior of the vehicle. Lateral acceleration is input to the anti-roll control unit 27. As shown in Figure 5, the anti-roll control unit 27 includes a differentiator 27A, a left wheel gain multiplier 27B, an inversion unit 27C, a right wheel gain multiplier 27D, a gain multiplier 27E, a pitch control processing unit 27F, a relative speed calculation unit 27G, an adder 27H, and a damping force characteristic processing unit 27J.

[0037] The differentiator 27A differentiates the lateral acceleration to calculate the jerk (lateral acceleration) relative to the vehicle's lateral (left-right) direction. The left wheel gain multiplier 27B multiplies the lateral acceleration by the left wheel gain and outputs the target damping force for the left wheel. The right wheel gain multiplier 27D multiplies the lateral acceleration, which has been multiplied by "-1" by the inversion unit 27C, by the right wheel gain and outputs the target damping force for the right wheel.

[0038] For example, if the derivative of the lateral acceleration (lateral jerk) is positive, the vehicle body is expected to sink towards the right wheel. Therefore, the left wheel side needs to be prepared for the extension of the damper, and the right wheel side needs to be prepared for the compression of the damper. Taking this into consideration, the reversal unit 27C multiplies the lateral jerk by "-1" before applying the right wheel gain.

[0039] The anti-roll control unit 27 extends the basic concept of G-vectoring, which enhances drivability, of "controlling longitudinal motion in accordance with lateral motion," and controls pitch motion in accordance with lateral motion. For this purpose, the gain multiplier unit 27E multiplies the lateral acceleration by a gain. The pitch control processing unit 27F derives a target damping force for pitch control that conforms to the extended concept of G-vectoring based on the lateral acceleration multiplied by the gain.

[0040] The relative velocity calculation unit 27G calculates the relative velocity from the lateral acceleration. The adder 27H adds the target damping force on the left wheel for pitch control to the target damping force on the left wheel for roll suppression and outputs the target damping force on the left wheel for controlling roll and pitch. The adder 27H adds the target damping force on the right wheel for pitch control to the target damping force on the right wheel for roll suppression and outputs the target damping force on the right wheel for controlling roll and pitch.

[0041] The damping force characteristic processing unit 27J is composed of a damping force map that shows, for example, the relationship between the target damping force and relative speed and the command value (control command) output to the variable damper 6. The damping force characteristic processing unit 27J outputs a control command to control the variable damper 6 on the left wheel side based on the target damping force and relative speed on the left wheel side. The damping force characteristic processing unit 27J outputs a control command to control the variable damper 6 on the right wheel side based on the target damping force and relative speed on the right wheel side. These control commands are anti-roll control commands and are, for example, control command values ​​(current values) that become command signals for the current to the variable damping force actuator 7.

[0042] As shown in Figure 3, the preliminary control command selection unit 28 receives an anti-dive squat control command and an anti-roll control command. The preliminary control command selection unit 28 compares the anti-dive squat control command and the anti-roll control command and selects the control command with the larger value (hardware value). The preliminary control command selection unit 28 outputs the value of the selected control command as the attitude stability control command value.

[0043] The ABS / TCS / ECS coordinated control unit 29 includes a target damping force calculation unit 29A and a damping force map 29B. The ABS / TCS / ECS coordinated control unit 29 receives relative speed from the observer 23 and ABS / TCS / ECS operation flags as signals from the brake / drive determination unit 31 via CAN8.

[0044] The target damping force calculation unit 29A, when it detects the operation of any of the ABS, TCS, or ECS based on the ABS / TCS / ECS operation flag, calculates the optimal target damping force for suppressing ground load fluctuations based on the damping ratio ζopt, coefficient Cc, and relative speed using the following formula Equation 1. Specifically, the target damping force calculation unit 29A determines the optimal target damping force for suppressing ground load fluctuations by multiplying the damping ratio ζopt, coefficient Cc, and relative speed. On the other hand, if the target damping force calculation unit 29A does not detect the operation of any of the ABS, TCS, or ECS based on the ABS / TCS / ECS operation flag, it sets the target damping force to 0 (zero).

[0045] In this case, the damping ratio ζopt is the optimal damping ratio for suppressing load fluctuations. The coefficient Cc is the critical damping coefficient. The damping ratio ζopt and coefficient Cc can be obtained in advance, for example, through experiments or simulations using actual vehicles.

[0046]

number

[0047] The damping force map 29B has pre-stored damping force characteristics. The target damping force is input to the damping force map 29B from the target damping force calculation unit 29A, along with the relative speed. Based on the target damping force and relative speed, the damping force map 29B outputs a coordinated control command corresponding to these. At this time, the coordinated control command is a control command value (current value), which is, for example, a command signal for the current to the variable damping force actuator 7.

[0048] The control command selection unit 30 compares the ride comfort control command, the attitude stability control command, and the coordinated control command, and selects the control command with the larger value. The control command selection unit 30 outputs the selected control command as the final control command. Specifically, the control command selection unit 30 selects the value that will be the hardware side among the ride comfort control command, the attitude stability control command, and the coordinated control command. At this time, the control command selection unit 30 performs the same process for each of the four wheel control commands. The damping force variable actuator 7 of the variable damper 6 is supplied with a drive current based on the final control command. As a result, the damping force of the variable damper 6 is controlled by the ECU 21.

[0049] The ECU21 according to the first embodiment has the configuration described above, and its operation will now be explained.

[0050] When vertical vibrations occur due to uneven road surfaces while the vehicle is in motion, the ECU 21 receives various vehicle driving information, sprung mass acceleration, unsprung mass acceleration, etc., from the CAN 8, sprung mass acceleration sensor 9, and unsprung mass acceleration sensor 10. At this time, the observer 23 determines the sprung mass velocity and relative velocity based on the sprung mass acceleration and unsprung mass acceleration.

[0051] The ride comfort control unit 24 of the ECU21 outputs ride comfort control commands to improve the vehicle's ride comfort based on the sprung speed and relative speed. The attitude stability control unit 25 of the ECU21 outputs attitude stability control commands to improve the vehicle's attitude stability based on the lateral acceleration and longitudinal acceleration input from CAN8. At this time, the attitude stability control commands are set to values ​​that suppress dive squat and roll.

[0052] The ABS / TCS / ECS coordinated control unit 29 of the ECU21 outputs a coordinated control command corresponding to a target damping force of 0 (zero) if it does not detect any operation of ABS, TCS, or ECS. In this case, the coordinated control command is a software-side value. At this time, the control command selection unit 30 of the ECU21 selects a hardware-side value from the ride comfort control command and the attitude stability control command. As a result, the ECU21 can achieve both ride comfort and attitude stability.

[0053] On the other hand, when the ABS / TCS / ECS coordinated control unit 29 of the ECU21 detects the operation of any of the ABS, TCS, or ECS, it determines the optimal target damping force for suppressing ground contact load fluctuations and outputs a coordinated control command corresponding to this target damping force. At this time, the control command selection unit 30 of the ECU21 selects the value that is on the hardware side from among the ride comfort control command, the attitude stability control command, and the coordinated control command. As a result, when any of the ABS, ECS, or TCS is activated, the ECU21 can reduce ground contact load fluctuations and improve vehicle stability.

[0054] Next, in order to confirm the vibration damping effect of the ECU21, the vibration damping performance was compared by vehicle simulation between a control method that omitted the ABS / TCS / ECS cooperative control unit 29 as a comparative example, and the control method according to the first embodiment. The simulation results are shown in Figures 6 to 8. As shown in Figure 6, in the first embodiment, the command value (current value) increases while the vehicle is decelerating with the ABS operating, compared to the comparative example. Also, in the first embodiment, the timing at which the longitudinal acceleration becomes 0 (zero) is earlier compared to the comparative example. From this, it can be seen that the vehicle can stop earlier in the first embodiment compared to the comparative example. Furthermore, as shown in Figure 7, in the first embodiment, the damping force is larger at the timing when the command value is increasing compared to the comparative example. In addition, as shown in Figure 8, it can be seen that in the first embodiment, the fluctuation of the wheel load is smaller compared to the comparative example, and the fluctuation of the ground contact load is also reduced.

[0055] Thus, the vehicle control system of the first embodiment includes a plurality of variable dampers 6 (force generating mechanisms) provided between the vehicle body 1 and the four wheels 2, each with an adjustable generating force between soft and hard, and an ECU 21 (control means) that variably controls the generating force of the variable dampers 6. When the ECU 21 receives a signal from a brake / drive determination unit 31 (ABS, ECS, TCS) that independently brakes or drives the four wheels 2, it adjusts the generating force of the variable dampers 6 so that the fluctuation of the contact load on the road surface by the variable dampers 6 becomes small.

[0056] Specifically, the ECU 21 (vehicle control unit) controls variable dampers 6 (actuators) that are installed between the vehicle body 1 and each of the four wheels 2, and which vary the force generated between the vehicle body 1 and the wheels 2. When the ECU 21 receives a signal from the braking / driving determination unit 31 (ABS, ECS, TCS) which independently brakes and drives the four wheels 2, it controls the variable dampers 6 so that the fluctuation in the contact load between the wheels 2 and the road surface due to the force generated by the variable dampers 6 is reduced.

[0057] As a result, when ABS, ECS, or TCS is activated, the ECU 21 controls the variable damper 6 so as to reduce the fluctuation in ground contact load between the wheel 2 and the road surface caused by the force generated by the variable damper 6. As a result, when ABS, ECS, or TCS is activated, the fluctuation in ground contact load can be reduced, thereby improving vehicle stability. Furthermore, in the first embodiment, since fluctuations in ground contact load caused by road surface input can be suppressed on rough road surfaces, the braking distance can be shortened. In other words, in the first embodiment, when stability is of utmost importance, such as when ABS, ECS, or TCS is activated, the damping ratio is set to minimize fluctuations in ground contact load, prioritizing ground contact. As a result, acceleration / deceleration performance and cornering performance can be improved in the first embodiment.

[0058] Next, Figures 1, 2, and 9 show a second embodiment of the present invention. The characteristic of the second embodiment is that when a signal is input from the braking / driving determination unit, the ABS / TCS / ECS cooperative control unit calculates a preset current command value that is optimal for suppressing ground load fluctuations without calculating the target damping force. In the second embodiment, the same reference numerals are used for the same components as in the first embodiment described above, and their descriptions are omitted.

[0059] The ECU41 according to the second embodiment is configured in substantially the same way as the ECU21 according to the first embodiment. The ECU41 constitutes a vehicle control device (control means) that controls the suspension device 4. The ECU41 is a controller that controls the force generated by the variable damper 6 (force generation mechanism). As shown in Figure 2, the ECU41 is equipped with a processor 42 as a control unit. The processor 42 is composed of a microcomputer or the like. The processor 42 controls the damping force of the variable damper 6 by executing a program stored in a memory unit (not shown). The input side of the ECU41 is connected to the CAN 8, sprung mass acceleration sensor 9, unsprung mass acceleration sensor 10, etc., and the output side is connected to the variable damper 6, etc.

[0060] Similar to the ECU21 in the first embodiment, the ECU41 includes a ride comfort control unit 24, a posture stability control unit 25, an ABS / TCS / ECS coordinated control unit 43, and a control command selection unit 30.

[0061] As shown in Figure 9, the ABS / TCS / ECS Coordination Control Unit 43 receives the ABS / TCS / ECS operation flag as a signal from the braking / driving determination unit 31 via CAN8. When the ABS / TCS / ECS Coordination Control Unit 43 detects the operation of ABS, TCS, or ECS based on the ABS / TCS / ECS operation flag, it calculates a preset current Ifopt as the front wheel command value and a current Iropt as the rear wheel command value using the following equation 2. At this time, the ABS / TCS / ECS Coordination Control Unit 43 outputs the front wheel command value and the rear wheel command value as a coordinated control command.

[0062] The front wheel command value is the optimal current command value for the front wheels to suppress ground load fluctuations. The rear wheel command value is the optimal current command value for the rear wheels to suppress ground load fluctuations. In this case, current Ifopt and current Iropt are determined based, for example, on the damping force characteristic map of the variable damper 6 and the value of a typical relative speed (e.g., 0.6 m / s) at which ground load fluctuations occur. Alternatively, the target damping force can be determined by substituting the value of a typical relative speed (e.g., 0.6 m / s) at which ground load fluctuations occur into equation 1, and then current Ifopt and current Iropt can be determined based on this target damping force and the damping force characteristic map. Note that the damping ratio ζopt and coefficient Cc tend to differ between the front and rear wheels. Therefore, current Ifopt and current Iropt will generally be different values.

[0063]

number

[0064] On the other hand, if the ABS / TCS / ECS coordinated control unit 43 does not detect the operation of all ABS, TCS, and ECS based on the ABS / TCS / ECS operation flag, it outputs a current value as a coordinated control command that softens the damping force.

[0065] Thus, the same effects and advantages as in the first embodiment can be obtained in the second embodiment configured in this way. Furthermore, in the second embodiment, the ABS / TCS / ECS cooperative control unit 43 outputs a preset current value as a cooperative control command depending on whether or not the ABS, TCS, or ECS is activated. Therefore, the computational load when calculating the cooperative control command can be reduced. Consequently, when any of the ABS, TCS, or ECS is activated, load fluctuations can be suppressed by simple computational processing.

[0066] In the second embodiment, an example was given in which the current command value of the cooperative control command was determined based on a typical relative speed value in which ground contact load fluctuation occurs. The present invention is not limited to this, and for example, the current command value that minimizes load fluctuation may be experimentally determined for a variable damper 6 mounted on a vehicle. Figures 10 and 11 show an example of the relationship between the current values ​​of the front and rear wheels and the wheel load fluctuation RMS (Root Mean Square) value. The ground contact load fluctuation RMS value corresponds to the ground contact load fluctuation. Figures 10 and 11 show an example of the characteristics of the left front wheel FL and left rear wheel RL, but the characteristics of the right front wheel FR and right rear wheel RR are similar. Figures 12 and 13 also show an example of the relationship between the piston speed and damping force of the variable dampers 6 of the front and rear wheels.

[0067] As shown in Figure 10, it can be seen that the ground contact load fluctuation is smallest at the front wheels with a command value of, for example, 0.9A. Similarly, it can be seen that the ground contact load fluctuation is smallest at the rear wheels with a command value of 1.6A. From these results, considering power consumption and unsprung weight contact, it can be concluded that 0.9A for the front wheels and 1.3A for the rear wheels are appropriate values. Therefore, the ABS / TCS / ECS cooperative control unit 43 may set the front wheel command value of the cooperative control command to 0.9A and the rear wheel command value of the cooperative control command to 1.3A when any of the ABS, TCS, or ECS is activated.

[0068] Next, Figures 1, 2, and 14 show a third embodiment of the present invention. The characteristic of the third embodiment is that the unsprung vibration control unit outputs an optimal current command value for suppressing ground load fluctuations when a signal is input from the damping drive determination unit. In the third embodiment, the same reference numerals are used for the same components as in the first embodiment described above, and their descriptions are omitted.

[0069] The ECU 51 according to the third embodiment is configured in substantially the same way as the ECU 21 according to the first embodiment. The ECU 51 constitutes a vehicle control device (control means) that controls the suspension device 4. The ECU 51 is a controller that controls the force generated by the variable damper 6 (force generation mechanism). As shown in Figure 2, the ECU 51 is equipped with a processor 52 as a control unit. The processor 52 is composed of a microcomputer or the like. The processor 52 controls the damping force of the variable damper 6 by executing a program stored in a memory unit (not shown). The input side of the ECU 51 is connected to the CAN 8, sprung mass acceleration sensor 9, unsprung mass acceleration sensor 10, etc., and the output side is connected to the variable damper 6, etc.

[0070] Similar to the ECU21 in the first embodiment, the ECU51 includes a ride comfort control unit 24, a posture stability control unit 25, and a control command selection unit 30. In addition, the ECU51 includes an unsprung vibration damping control unit 53.

[0071] As shown in Figure 14, the unsprung vibration control unit 53 outputs an unsprung vibration control command to suppress vibrations in the unsprung mass. Specifically, the unsprung vibration control unit 53 uses the relative acceleration output from the observer 23 to determine whether the vehicle has overcome a protrusion. The positive and negative slopes of the characteristic curve showing relative acceleration in Figure 16 roughly correspond to the extension stroke and compression stroke of the variable damper 6, respectively. The unsprung vibration control unit 53 uses the first to fourth relative acceleration thresholds Kα1 to Kα4 as thresholds used in the determination process.

[0072] The unsprung vibration damping control unit 53 uses the relative acceleration-corresponding reference state Jα0 and the relative acceleration-corresponding first to third states Jα1 to Jα3 when performing the determination process (see Figure 15). Here, the relative acceleration-corresponding reference state Jα0 and the relative acceleration-corresponding first to third states Jα1 to Jα3 refer to the following states.

[0073] The relative acceleration reference state Jα0 refers to the state (initial state) when the vehicle starts moving and the magnitude of the extension and compression of the variable damper 6's operating stroke is less than a predetermined value. In the relative acceleration reference state Jα0, the unsprung vibration control unit 53 performs control (hereinafter referred to as command value soft control) that outputs an unsprung vibration control command to soften the damping force characteristics of the variable damper 6. Note that the relative acceleration reference state Jα0 indicates the initial state in which no control is performed regarding protrusions, and is referred to as "soft" for the sake of explanation, but is not limited to this.

[0074] The first relative acceleration-dependent state Jα1 is a state in which (i) the first timer performs timing (counting) and (ii) command value soft control is performed (command value = soft). The relative acceleration-dependent second state Jα2 refers to a state in which (i) the second timer performs timing (counting), and (ii) command value soft control is performed (command value = soft). The relative acceleration-responsive third state Jα3 refers to a state in which (i) the third timer performs timing (counting), and (ii) controls are performed to output an unsprung vibration control command (cooperative control command) that sets the damping force characteristics of the variable damper 6 to characteristics that suppress fluctuations in ground load (the command value = the current value that suppresses fluctuations in ground load).

[0075] In the third embodiment, transitions between states Jα0, Jα1, Jα2, and Jα3 are performed based on the count values ​​of the first timer, second timer, and third timer, and the relative acceleration.

[0076] The unsprung vibration control unit 53 performs a bump-crossing determination process based on relative acceleration and outputs an unsprung vibration control command based on the result of this determination process. In the relative acceleration-corresponding reference state Jα0, the unsprung vibration control unit 53 outputs an unsprung vibration control command to soften the damping force characteristics of the variable damper 6. The calculation contents of the unsprung vibration control unit 53 will now be explained with reference to Figures 15 and 16.

[0077] In Figures 15 and 16, the unsprung vibration control unit 53 determines whether or not the vehicle equipped with the ECU 51 is traveling over a protrusion (and therefore whether or not it is traveling over a protrusion) when the vehicle is traveling in the relative acceleration-corresponding reference state Jα0.

[0078] If it is determined that the movement is a protrusion, it is determined whether or not it is a compression stroke (relative acceleration < 0), and whether or not condition A is met, which is that the relative acceleration is smaller than a predetermined threshold (hereinafter referred to as the first threshold for compression side relative acceleration) Kα1 (relative acceleration < first threshold for compression side relative acceleration Kα1) [in other words, a compression stroke of a magnitude exceeding the first threshold for compression side relative acceleration Kα1 is detected]. If condition A is met, that is, if a compression stroke of a magnitude exceeding the first threshold for compression side relative acceleration Kα1 is detected, the system transitions to the first relative acceleration corresponding state Jα1 and starts timing using a timer (first relative acceleration timer) (the value obtained by this timing is called the first timer value Tα1).

[0079] Furthermore, the unsprung vibration control unit 53 receives the ABS / TCS / ECS operation flag as a signal from the braking / driving determination unit 31 via CAN8. The unsprung vibration control unit 53 determines whether condition B is met, which is that the ABS / TCS / ECS operation flag is ON and the operation of one of the ABS, TCS, or ECS has been detected. If condition B is met, that is, if the operation of one of the ABS, TCS, or ECS has been detected, the unit transitions to the relative acceleration-corresponding third state Jα3.

[0080] If neither condition A nor condition B is met (relative acceleration ≥ relative acceleration compression side first threshold Kα1, and the ABS / TCS / ECS activation flag is OFF), the relative acceleration corresponding reference state Jα0 is maintained.

[0081] In the first relative acceleration response state Jα1, it is determined whether the condition (hereinafter referred to as the first relative acceleration response condition) is met, which indicates that the relative acceleration is greater than a predetermined threshold (hereinafter referred to as the second relative acceleration threshold) Kα2 defined in the extension stroke (relative acceleration > 0). If this first relative acceleration response condition is met (relative acceleration > second relative acceleration threshold Kα2), the system transitions to the second relative acceleration response state Jα2 and starts timing using a timer (second relative acceleration timer) (the value obtained by this timing is called the second timer value Tα2). On the other hand, if the condition (hereinafter referred to as the second relative acceleration response condition) is met, which is that the first timer value Tα1 exceeds the set time (Tα1 > set time), the system transitions to the reference relative acceleration response state Jα0. If neither of the two conditions (first and second relative acceleration response conditions) is met (relative acceleration ≤ second relative acceleration threshold Kα2, and Tα1 ≤ set time), the system maintains the first relative acceleration response state Jα1.

[0082] In the relative acceleration-responsive second state Jα2, when the condition (hereinafter referred to as the relative acceleration-responsive third condition) is met, indicating that the relative acceleration has fallen below a predetermined threshold (hereinafter referred to as the relative acceleration third threshold) Kα3 (in other words, detecting a compression stroke in which the magnitude of the relative velocity corresponding to the relative acceleration exceeds the threshold of the relative velocity corresponding to the relative acceleration third threshold Kα3), the system transitions to the relative acceleration-responsive third state Jα3 and starts timing using a timer (relative acceleration third timer) (the value obtained by this timing is called the third timer value Tα3). On the other hand, when the condition (hereinafter referred to as the relative acceleration-responsive fourth condition) is met, indicating that the second timer value Tα2 has exceeded the set time, the system transitions to the relative acceleration-responsive base state Jα0. If neither of the two conditions (relative acceleration-responsive third and fourth conditions) is met (relative acceleration is not less than or equal to zero, and Tα2 ≤ set time), the system maintains the relative acceleration-responsive second state Jα2.

[0083] In the third relative acceleration response state Jα3, which is the optimal timing for simultaneously preventing deterioration of sprung mass acceleration during the initial overshoot and suppressing unsprung mass fluttering, the command value is set to the optimal current command value for suppressing ground load fluctuations. Specifically, the command value is set to the front wheel current command value (current Ifopt) and rear wheel current command value (current Iropt) used in the second embodiment. Furthermore, if condition C, which indicates that the third timer value Tα3 has exceeded the set time (Tα3 > set time), or condition D, which indicates that the ABS / TCS / ECS operation flag is OFF (hereinafter, including conditions C and D, this is referred to as the fifth relative acceleration response condition), is met, the system transitions to the relative acceleration response reference state Jα0 and terminates control. If the fifth relative acceleration response condition is not met (Tα3 ≤ set time, and the ABS / TCS / ECS operation flag is ON), the third relative acceleration response state Jα3 is maintained, and the command value is held at the optimal current command value for suppressing ground load fluctuations.

[0084] Furthermore, if condition E, which indicates that the relative acceleration exceeds the threshold (hereinafter referred to as the fourth relative acceleration threshold) Kα4 (relative acceleration > Kα4), or condition F, which indicates that the ABS / TCS / ECS operation flag is ON (hereinafter referred to as the sixth relative acceleration response condition, including conditions E and F), is met, the third relative acceleration timer is cleared and restarted. If the fifth and sixth relative acceleration response conditions are not met, the third relative acceleration response state Jα3 is maintained, and the command value is held at the optimal current command value for suppressing ground load fluctuations.

[0085] As described above, the unsprung vibration damping control unit 53 transitions to the third relative acceleration state Jα3 when the first relative acceleration corresponding condition is met, which is that the relative acceleration is greater than the second relative acceleration threshold Kα2 (which is determined in relation to the positive slope portion of the characteristic curve showing relative acceleration), and the third relative acceleration corresponding condition is met, which is that the relative acceleration is less than the third relative acceleration threshold Kα3 (detecting a compression stroke in which the magnitude of the relative velocity corresponding to the relative acceleration exceeds the threshold of the relative velocity corresponding to the third relative acceleration threshold Kα3). This results in damping force characteristics that suppress fluctuations in ground contact load. As a result, the impact on the vehicle body 1 and, consequently, the occupants when driving over bumps can be reduced, thereby improving ride comfort and posture stability.

[0086] As described above, by controlling the suspension as described, the control starts earlier than the first stroke reversal from extension to compression when crossing a protrusion. However, due to the dynamics of the ECU 51 and variable damper 6, the actual switching of the damping force is delayed. Therefore, by appropriately setting the value of the third relative acceleration threshold Kα3, the damping force characteristics can be switched in synchronization with the timing of the stroke reversal from extension to compression. Thus, it is possible to maintain the initial sprung mass acceleration and suppress subsequent fluttering.

[0087] Furthermore, when the ABS / TCS / ECS activation flag is turned ON, the unsprung vibration control unit 53 transitions to the relative acceleration-responsive third state Jα3, providing damping force characteristics that suppress fluctuations in ground contact load. This reduces fluctuations in ground contact load when any of the ABS, ECS, or TCS are activated, thereby improving vehicle stability.

[0088] Thus, the same effects and advantages as in the first embodiment can be obtained in the third embodiment configured in this way. Furthermore, in the third embodiment, the ECU 51 is equipped with an unsprung vibration control unit 53 for suppressing unsprung vibrations, and when a signal is input from the braking / driving determination unit 31, the unsprung vibration control unit 53 outputs an unsprung vibration control command as a coordinated control command value so as to reduce fluctuations in the contact load on the road surface caused by the variable damper 6. Specifically, when the ABS, TCS, or ECS is activated, the unsprung vibration control unit 53 uses control processing to suppress unsprung vibrations and outputs an optimal current command value for suppressing contact load fluctuations as an unsprung vibration control command as a coordinated control command value. For this reason, when any of the ABS, TCS, or ECS is activated, load fluctuations can be suppressed using the unsprung vibration control command.

[0089] In the third embodiment, the unsprung vibration control unit 53 outputs a preset current command value (front wheel current command value, rear wheel current command value) as a control command value for suppressing ground load fluctuations, similar to the ABS / TCS / ECS coordinated control unit 43 in the second embodiment, when the ABS, TCS, and ECS are activated. However, the present invention is not limited thereto. For example, when the ABS, TCS, and ECS are activated, the unsprung vibration control unit 53 may output a control command value based on a target damping force optimal for suppressing ground load fluctuations, similar to the ABS / TCS / ECS coordinated control unit 29 in the first embodiment.

[0090] In the third embodiment, the unsprung vibration control unit 53 transitions states based on the relative acceleration between the sprung mass and the unsprung mass. However, the present invention is not limited thereto. For example, as disclosed in Japanese Patent Application Publication No. 2010-235019, the unsprung vibration control unit 53 may transition states based on the relative velocity between the sprung mass and the unsprung mass.

[0091] Next, Figures 1, 2, and 17 show a fourth embodiment of the present invention. The characteristic of the fourth embodiment is that, when a signal is input from the braking / driving determination unit, the cooperative control command priority selection unit prioritizes selecting a cooperative control command that reduces the fluctuation of the contact load on the road surface caused by the variable damper. In the fourth embodiment, the same reference numerals are used for the same components as in the second embodiment described above, and their descriptions are omitted.

[0092] The ECU61 according to the fourth embodiment is configured in substantially the same way as the ECU41 according to the second embodiment. The ECU61 constitutes a vehicle control device (control means) that controls the suspension device 4. The ECU61 is a controller that controls the force generated by the variable damper 6 (force generation mechanism). As shown in Figure 2, the ECU61 is equipped with a processor 62 as a control unit. The processor 62 is composed of a microcomputer or the like. The processor 62 controls the damping force of the variable damper 6 by executing a program stored in a memory unit (not shown). The input side of the ECU61 is connected to the CAN 8, sprung mass acceleration sensor 9, unsprung mass acceleration sensor 10, etc., and the output side is connected to the variable damper 6, etc.

[0093] Similar to the ECU41 in the second embodiment, the ECU61 includes a ride comfort control unit 24, a posture stability control unit 25, an ABS / TCS / ECS coordinated control unit 43, a control command selection unit 63, and a coordinated control command priority selection unit 64.

[0094] As shown in Figure 17, the control command selection unit 63 compares the ride comfort control command and the attitude stability control command and selects the control command with the larger value. Specifically, the control command selection unit 63 selects the value that corresponds to the hardware side of the ride comfort control command and the attitude stability control command. At this time, the control command selection unit 63 performs the same process for each of the four wheel control commands.

[0095] The Coordinated Control Command Priority Selection Unit 64 receives the ABS / TCS / ECS operation flag as a signal from the Brake / Drive Judgment Unit 31 via CAN8. If the ABS / TCS / ECS operation flag is OFF and no operation of ABS, TCS, or ECS is detected, the Coordinated Control Command Priority Selection Unit 64 selects the control command output from the Control Command Selection Unit 63. In this case, the Coordinated Control Command Priority Selection Unit 64 outputs the selected control command as the final control command. At this time, the variable damping force actuator 7 of the variable damper 6 is supplied with a drive current based on either the ride comfort control command or the attitude stability control command. As a result, the damping force of the variable damper 6 is controlled by the ECU 61.

[0096] On the other hand, when the ABS / TCS / ECS operation flag is turned ON and the operation of any of ABS, TCS, or ECS is detected, the cooperative control command priority selection unit 64 selects the cooperative control command output from the ABS / TCS / ECS cooperative control unit 43. At this time, the variable damping force actuator 7 of the variable damper 6 is supplied with a drive current based on the cooperative control command. As a result, the damping force of the variable damper 6 is controlled by the ECU 61.

[0097] Thus, the same effects and advantages as those of the first and second embodiments can be obtained in this fourth embodiment as well. Furthermore, in the fourth embodiment, the ECU 61 includes a posture stability control unit 25 that outputs a posture stability control command value for controlling the variable damper 6 in accordance with the input change in the posture of the vehicle, and a ride comfort control unit 24 that outputs a ride comfort control command value for controlling the variable damper 6 in accordance with the input sprung mass vibration of the vehicle. When a signal is input from the braking / driving determination unit 31, the ECU 61 prioritizes the cooperative control command value and controls the force generated by the variable damper 6.

[0098] Specifically, when a signal is input from the braking / driving judgment unit 31 (when the ABS / TCS / ECS operation flag is ON), the cooperative control command priority selection unit 64 of the ECU 61 prioritizes selecting a cooperative control command that reduces fluctuations in the contact load on the road surface caused by the variable damper 6. Therefore, when any of ABS, ECS, or TCS is activated, the ECU 61 controls the variable damper 6 so that fluctuations in the contact load between the wheel 2 and the road surface due to the force generated by the variable damper 6 are reduced. As a result, when any of ABS, ECS, or TCS is activated, regardless of the ride comfort control command or attitude stability control command, fluctuations in the contact load can be reduced and the stability of the vehicle can be improved.

[0099] In the fourth embodiment, the ABS / TCS / ECS cooperative control unit 43 switches the current command value according to whether the ABS / TCS / ECS operation flag is ON or OFF. However, the present invention is not limited thereto. The ABS / TCS / ECS cooperative control unit according to the fourth embodiment may output a preset current command value that is optimal for suppressing ground load fluctuations, regardless of whether the ABS / TCS / ECS operation flag is ON or OFF. Even in this case, the cooperative control command priority selection unit 64 prioritizes and selects the cooperative control command only when the ABS / TCS / ECS operation flag is ON and outputs it.

[0100] In the fourth embodiment, the case in which the cooperative control command priority selection unit 64, etc., is applied to the second embodiment was described as an example, but it may also be applied to the first and third embodiments.

[0101] In the embodiments described above, the case in which a semi-active suspension is configured using a variable damper 6 as an actuator (force generating mechanism) was explained as an example. The present invention is not limited to this, and the actuator may also constitute an active suspension that generates vertical force between the vehicle body and the wheels. Specifically, the actuator may be an electric actuator, hydraulic actuator, etc., that generates extension or contraction force between the vehicle body and the wheels.

[0102] In each of the embodiments described above, the actuator (force generating mechanism) that generates an adjustable force between the vehicle body 1 and the wheels 2 was described as being configured with a damping force adjustable variable damper 6. The present invention is not limited to this, and for example, the actuator may be configured with an air suspension, stabilizer (Kinesus), electromagnetic suspension, etc., in addition to a hydraulic shock absorber.

[0103] In each of the above embodiments, the attitude stability control unit 25 outputs an attitude stability control command that takes into account both the anti-dive squat control command and the anti-roll control command. The present invention is not limited to this, and the attitude stability control unit may output an attitude stability control command that is either the anti-dive squat control command or the anti-roll control command. That is, the attitude stability control command may be either the anti-dive squat control command or the anti-roll control command. For this reason, the attitude stability control unit may be configured to omit either the anti-dive squat control unit or the anti-roll control unit.

[0104] In each of the above embodiments, the ECUs 21, 41, 51, and 61 are equipped with a ride comfort control unit 24 and a posture stability control unit 25. The present invention is not limited to these, and the ECU may omit either the ride comfort control unit or the posture stability control unit. Alternatively, the ECU may omit both the ride comfort control unit and the posture stability control unit and be equipped with other control units.

[0105] In the embodiments described above, suspension systems used in four-wheeled automobiles were used as examples. However, the present invention is not limited to these, and can also be applied to two-wheeled and three-wheeled automobiles, or to work vehicles, transport vehicles such as trucks and buses.

[0106] The embodiments described above are illustrative, and it is possible to partially substitute or combine the configurations shown in different embodiments or modifications. The following embodiments are possible vehicle control systems included in each of the above embodiments. A vehicle control system according to the first embodiment is: The vehicle comprises a plurality of force generating mechanisms, each provided between the vehicle body and the four wheels, with the generated force adjustable between soft and hard, and control means for variably controlling the generated force of the force generating mechanisms. The control means is The vehicle includes an unsprung vibration control unit that outputs an unsprung vibration control command value for suppressing unsprung vibrations based on signals from a braking / driving determination unit that independently brakes and drives the four wheels and signals of relative acceleration between the vehicle body and the wheels, and adjusts the force generated by the force generating mechanism so that fluctuations in the contact load on the road surface by the force generating mechanism are reduced based on the unsprung vibration control command value. A vehicle control system according to a second embodiment is a vehicle control system according to the first embodiment, The control means is A posture stability control unit that outputs a posture stability control command value for controlling the force generation mechanism in response to the input change in the posture of the vehicle, A ride comfort control unit that outputs a ride comfort control command value for controlling the force generation mechanism in response to the input sprung mass vibration of the vehicle, A control command selection unit that outputs a control command to the force generation mechanism based on the attitude stability control command value, the ride comfort control command value, and the unsprung vibration damping control command value, It is equipped with. A vehicle control system according to a third embodiment is a vehicle control system according to the second embodiment, The control command selection unit is, The highest command value among the input attitude stability control command value, ride comfort control command value, and unsprung vibration damping control command value is selected. A vehicle control system according to the fourth embodiment is a vehicle control system according to the second embodiment, When a signal is output from the braking / driving determination unit, the control means adjusts the force generated by the force generating mechanism based on the unsprung vibration control command value among the attitude stability control command value, the ride comfort control command value, and the unsprung vibration control command value. [Explanation of Symbols]

[0107] 1: Vehicle body, 2: Wheels, 4: Suspension system, 6: Variable damper (adjustable damping force shock absorber, actuator, force generation mechanism), 7: Variable damping force actuator, 8: CAN, 9: Sprung mass acceleration sensor, 10: Unsprung mass acceleration sensor, 21, 41, 51, 61: ECU (control means, vehicle control device), 24: Ride comfort control unit, 25: Posture stability control unit, 29, 43: ABS / TCS / ECS coordinated control unit, 30, 63: Control command selection unit, 31: Braking / driving judgment unit, 53: Unsprung mass vibration damping control unit, 64: Coordinated control command priority selection unit

Claims

1. A vehicle comprising a plurality of force generating mechanisms, each provided between the vehicle body and the four wheels, the force generated being adjustable between soft and hard, and control means for variably controlling the force generated by the force generating mechanisms, The control means is A vehicle control system comprising an unsprung vibration control unit that outputs an unsprung vibration control command value for suppressing unsprung vibration based on signals from a braking / driving determination unit that independently brakes and drives the four wheels and signals of relative acceleration between the vehicle body and the wheels, and adjusting the force generated by the force generating mechanism based on the unsprung vibration control command value so that fluctuations in the contact load on the road surface by the force generating mechanism are reduced.

2. The control means is A posture stability control unit that outputs a posture stability control command value for controlling the force generation mechanism in response to the input change in the posture of the vehicle, A ride comfort control unit that outputs a ride comfort control command value for controlling the force generation mechanism in response to the input sprung mass vibration of the vehicle, A control command selection unit that outputs a control command to the force generation mechanism based on the attitude stability control command value, the ride comfort control command value, and the unsprung vibration damping control command value, The vehicle control system according to claim 1, comprising:

3. The control command selection unit is: The vehicle control system according to claim 2, which selects the highest command value among the input attitude stability control command value, the ride comfort control command value, and the unsprung vibration damping control command value.

4. The vehicle control system according to claim 2, wherein when a signal is output from the braking / driving determination unit, the control means adjusts the force generated by the force generating mechanism based on the unsprung vibration control command value among the attitude stability control command value, the ride comfort control command value, and the unsprung vibration control command value.

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