Vehicle behavior control device and damper

Abstract

A controller (11) comprises: a front wheel speed determination unit (20) that determines whether a value of a wheel speed change of a front wheel is in a front wheel speed change tendency greater than a front wheel threshold value; a rear wheel speed determination unit (21) that determines whether a wheel speed change of a rear wheel is a rear wheel speed change greater than a rear wheel threshold value; a speed bump control unit (22) that determines there is a speed bump and outputs a speed bump command value when the front wheel speed determination unit (20) determines that the front wheel speed change is an increase or decrease and the rear wheel speed determination unit (21) determines that the determination result of the rear wheel speed change is an increase; and a pothole control unit (23) that determines there is a pothole and outputs a pothole command value when the front wheel speed determination unit (20) determines that the front wheel speed change is an increase or decrease and the rear wheel speed determination unit (21) determines that the determination result of the rear wheel speed change is a decrease.

Description

Vehicle behavior control system and damper

[0001] This disclosure relates to a vehicle behavior control device and damper that control a force generation mechanism provided between the vehicle body and the wheels.

[0002] When an excessive impact force is applied to the damper, the damper may fully compress, causing the damper case to come into contact with the vehicle body (bump touch). To suppress such bump touch, the suspension device described in Patent Document 1 increases the damping force when it is determined that the wheel speed is increasing and the differential value of the wheel speed has changed to an increasing value that exceeds a predetermined threshold.

[0003] Japanese Patent Publication No. 2018-43722

[0004] By the way, the suspension device described in Patent Document 1 can suppress the damper from being fully compressed, but it does not take into account the case where the damper changes in the direction of extension. Therefore, there is a problem that the damper cannot be properly controlled when the damper changes in the direction of extension, such as when a vehicle passes through a pothole.

[0005] An object of one embodiment of the present invention is to provide a vehicle behavior control device and a damper that can appropriately control the damper when the damper changes in the direction of extension.

[0006] One embodiment of the present invention is a vehicle behavior control device that controls a force generating mechanism provided between the vehicle body and the wheels of a vehicle and generating an adjustable force between the vehicle body and the wheels, comprising: a front wheel speed determination unit that determines whether the value of the change in the front wheel speed is greater than a front wheel threshold; a rear wheel speed determination unit that determines whether the change in the rear wheel speed is greater than a rear wheel threshold; a speed bump control unit that determines it to be a speed bump and outputs a speed bump command value when the front wheel speed determination unit determines that the change in the front wheel speed is increasing or decreasing, and the rear wheel speed determination unit determines that the result of the determination of the change in the rear wheel speed is increasing; and a pothole control unit that determines it to be a pothole and outputs a pothole command value when the front wheel speed determination unit determines that the change in the front wheel speed is increasing or decreasing, and the rear wheel speed determination unit determines that the result of the determination of the change in the rear wheel speed is decreasing.

[0007] One embodiment of the present invention is a vehicle behavior control device that controls a force generating mechanism provided between the vehicle body and the wheels of a vehicle and generating an adjustable force between the vehicle body and the wheels, comprising: a front wheel speed determination unit that determines whether the value of the change in front wheel speed is greater than a front wheel threshold value and is a front wheel speed change trend; a speed bump control unit that determines it is a speed bump and outputs a speed bump command value when the front wheel speed determination unit determines that the change in front wheel speed corresponds to either an increase or a decrease in speed, and a pothole control unit that determines it is a pothole and outputs a pothole command value when the front wheel speed determination unit determines that it corresponds to either an increase or a decrease in front wheel speed and is the other,

[0008] One embodiment of the present invention is a damper mounted on a vehicle and having an adjustable damping force, the damper comprising: a bottomed cylindrical cylinder filled with working fluid; a piston dividing the inside of the cylinder into a first chamber and a second chamber; a damping force adjustment unit that adjusts the damping force by adjusting the flow of the working fluid; and a control unit that controls the amount of adjustment of the damping force, the control unit comprising: a front wheel speed determination unit that determines whether the value of the change in the wheel speed of the front wheels is greater than a front wheel threshold; and a rear wheel speed determination unit that determines whether the change in the wheel speed of the rear wheels is greater than a rear wheel threshold. The system includes: a rear wheel speed determination unit that determines whether there is a change; a speed bump control unit that determines it is a speed bump and outputs a speed bump command value when the front wheel speed determination unit determines that the front wheel speed change is increasing or decreasing, and the rear wheel speed determination unit determines that the result of the rear wheel speed change determination is increasing; and a pothole control unit that determines it is a pothole and outputs a pothole command value when the front wheel speed determination unit determines that the front wheel speed change is increasing or decreasing, and the rear wheel speed determination unit determines that the result of the rear wheel speed change determination is decreasing.

[0009] One embodiment of the present invention is a damper mounted on a vehicle and having an adjustable damping force, the damper comprising: a bottomed cylindrical cylinder filled with working fluid; a piston that divides the inside of the cylinder into a first chamber and a second chamber; a damping force adjustment unit that adjusts the damping force by adjusting the flow of the working fluid; and a control unit that controls the amount of damping force adjustment, wherein the control unit comprises: a front wheel speed determination unit that determines whether the value of the change in front wheel speed is greater than a front wheel threshold; a speed bump control unit that determines it is a speed bump and outputs a speed bump command value when the front wheel speed determination unit determines that the change in front wheel speed corresponds to either an increase or a decrease in speed, and a pothole control unit that determines it is a pothole and outputs a pothole command value when the front wheel speed determination unit determines that it corresponds to either an increase or a decrease in front wheel speed, or the other.

[0010] According to one embodiment of the present invention, the damper can be appropriately controlled when it changes in the direction of extension.

[0011] This is an overall configuration diagram showing a four-wheeled vehicle to which a vehicle behavior control device according to an embodiment of the present invention is applied. This is a schematic diagram showing a damper mounted on the vehicle in Figure 1. This is a block diagram of the controller in Figure 2. This is a block diagram of the speed bump / pothole control current calculation unit according to the first to third embodiments. This is a flowchart of the speed bump / pothole control process according to the first embodiment. This is an explanatory diagram showing the relationship between the rear wheel threshold and the control for speed bumps and potholes for the first embodiment. This is an explanatory diagram showing the state in which the front wheels of the vehicle enter a speed bump. This is an explanatory diagram showing the state in which the front wheels of the vehicle enter a pothole. This is an explanatory diagram showing the state in which the front wheels of the vehicle enter a low-μ surface. This is an explanatory diagram showing the relationship between the difference between the differential value of the front wheel speed, the differential value of the rear wheel speed, and the longitudinal acceleration in situations of speed bumps, potholes, and sudden changes in wheel speed of only the front wheels. This is a characteristic diagram showing the time change of the control command value, road surface judgment, piston speed, differential value of the wheel speed, and longitudinal acceleration when the vehicle is traveling over a speed bump. This is a characteristic diagram showing an enlarged view of the time variation of the wheel velocity derivative and longitudinal acceleration in section XII of Figure 11. This is a characteristic diagram showing the time variation of the control command value, road surface determination, piston speed, wheel velocity derivative, and longitudinal acceleration when the vehicle is traveling over a pothole. This is a characteristic diagram showing an enlarged view of the time variation of the wheel velocity derivative and longitudinal acceleration in section XIV of Figure 13. This is a flowchart of the speed bump / pothole control process according to the second embodiment. This is a flowchart of the speed bump / pothole control process according to the third embodiment. This is an explanatory diagram showing the relationship between the rear wheel threshold and the speed bump control, pothole control, and conveyor-equivalent current command for the third embodiment. This is a block diagram showing the speed bump / pothole control current calculation unit according to the fourth and fifth embodiments. This is a flowchart of the speed bump / pothole control process according to the fourth embodiment. This is an explanatory diagram showing the relationship between the front wheel threshold and the speed bump control, pothole control, and normal control for the fourth embodiment. This is a flowchart of the speed bump / pothole control process according to the fifth embodiment.This is an explanatory diagram showing the relationship between the front wheel threshold and the control for speed bumps, potholes, and normal control according to the fifth embodiment. This is a block diagram of the speed bump / pothole control current calculation unit according to the sixth embodiment. This is a flowchart showing the speed bump / pothole control process according to the sixth embodiment.

[0012] The vehicle behavior control device according to an embodiment of the present invention will be described in detail below, with reference to the attached drawings, using the application of the vehicle behavior control device to a four-wheeled vehicle as an example.

[0013] Figures 1 and 2 show a vehicle 1 to which the vehicle behavior control device of the present invention is applied. Vehicle 1 includes, for example, a suspension device 5 and a controller 11 (ECU). In Figure 1, the lower side of the vehicle body 2, which constitutes the vehicle body, is provided with, for example, left and right front wheels and left and right rear wheels (hereinafter collectively referred to as wheels 3). These wheels 3 include tires 4, and the tires 4 act as springs that absorb fine irregularities in the road surface.

[0014] The suspension device 5 is a shock absorber provided by the vehicle 1. The suspension device 5 is installed interposed between the vehicle body 2 and the wheels 3. This suspension device 5 consists of a suspension spring 6 (hereinafter referred to as the spring 6) and a damping force adjustable shock absorber (hereinafter referred to as the variable damper 7) installed in parallel with the spring 6 between the vehicle body 2 and the wheels 3.

[0015] Note that Figure 2 shows a case where one set of suspension devices 5 is installed between the vehicle body 2 and the wheels 3. However, the suspension devices 5 can be installed in a total of four sets, for example, individually and independently between the four wheels 3 and the vehicle body 2, and only one of these sets is schematically shown in Figure 2.

[0016] 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. The variable damper 7 is a force generating mechanism provided between the vehicle body 2 and the wheel 3 of the vehicle 1, which generates an adjustable force between the vehicle body 2 and the wheel 3.

[0017] The variable damper 7 includes a bottomed cylindrical cylinder 7A filled with working fluid, a piston 7B that divides the inside of the cylinder 7A into a first chamber and a second chamber, and a damping force variable actuator 8 which serves as a damping force adjustment unit that adjusts the damping force by adjusting the flow of working fluid.

[0018] The variable damper 7 is equipped with a damping force variable actuator 8, such as a damping force adjustment valve, to continuously adjust the damping force characteristics (i.e., damping force characteristics) from hard characteristics to soft characteristics. The damping force variable actuator 8 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. The variable damper 7 may also be a pressure-controlled type or a flow-control type. The variable damper 7 may also be a type that controls viscosity, such as a magnetorheological fluid or an electroviscous fluid.

[0019] CAN9 (Controller Area Network) is connected to controller 11. CAN9 transmits data related to the vehicle's behavior (hereinafter referred to as behavior information). This behavior information includes, for example, longitudinal acceleration (longitudinal G), lateral acceleration (lateral G), steering angle, yaw rate, command current (FB current), and wheel speed. As a result, controller 11 can obtain vehicle behavior information such as wheel speed and vehicle speed through CAN9.

[0020] In this embodiment, CAN is used as an example of an in-vehicle network, but other in-vehicle networks may be used. Examples of in-vehicle networks include CAN FD (CAN with Flexible Data rate), FlexRay, and in-vehicle Ethernet.

[0021] The controller 11 is a vehicle behavior control device that controls the variable damper 7 (force generation mechanism). In this case, the damper of the present invention includes a bottomed cylindrical cylinder 7A filled with working fluid, a piston 7B that divides the inside of the cylinder 7A into a first chamber and a second chamber, a damping force variable actuator 8 (damping force adjustment unit) that adjusts the damping force by adjusting the flow of working fluid, and a controller 11 as a control unit that controls the amount of damping force adjustment.

[0022] The controller 11 is configured, for example, by a microcomputer. The controller 11 has a storage unit 12 consisting of ROM, RAM, non-volatile memory, etc. The storage unit 12 of the controller 11 stores various programs, information (sensor position, vehicle specifications), data, etc. for controlling the variable damper 7. The input side of the controller 11 is connected to CAN 9, which is a network necessary for data communication. The output side of the controller 11 is connected to the damping force variable actuator 8 of the variable damper 7.

[0023] The controller 11 acquires vehicle behavior information through the CAN 9. Based on the behavior information, the controller 11 estimates the vehicle state variables. Based on the estimated vehicle state variables, the controller 11 determines the force that should be generated by the variable damper 7 (force generation mechanism) of the suspension device 5, and outputs the control signal (command current) to the damping force variable actuator 8 of the suspension device 5.

[0024] As shown in Figure 2, the controller 11 includes a receiving unit 13, a vehicle state estimation unit 14, and a damping force control unit 15.

[0025] The receiving unit 13 acquires vehicle behavior information, including wheel speed, through the CAN 9. The vehicle state estimation unit 14 estimates vehicle state quantities based on the vehicle behavior information acquired by the receiving unit 13. At this time, vehicle state quantities include, for example, sprung mass vertical speed (sprung mass velocity), relative displacement, relative speed (piston speed), pitch rate, etc. The vehicle state estimation unit 14 outputs these estimated values. In addition, the vehicle state estimation unit 14 performs a road surface determination based on the vehicle behavior information acquired by the receiving unit 13 and outputs the determination result.

[0026] The vehicle state estimation unit 14 estimates the sprung speed, relative displacement, relative velocity, and pitch rate of each wheel as vehicle state quantities based on the wheel speed, etc. The vehicle state estimation unit 14 includes, for example, a neural network (not shown) as artificial intelligence (AI). The neural network is composed of a three-layer hierarchical neural network in which elements of an input layer, a hidden layer, and an output layer are hierarchically connected. Each element of the input layer and each element of the hidden layer are connected with weights. Each element of the hidden layer and each element of the output layer are connected with different weights. This weight information is weight parameters, which are determined in advance by machine learning and stored in the memory unit 12. Note that the number of hidden layers is not limited to one. The neural network may have two or more hidden layers.

[0027] The input layer of the neural network receives time-series data of behavioral information (e.g., wheel speed of each wheel, longitudinal acceleration of the vehicle, etc.). The output layer outputs instantaneous values ​​of the sprung and unsprung velocities of a suspension device 5, assumed to be mounted on each wheel 3 of vehicle 1. The number of elements in the hidden layer is generally determined from the number of elements in the input and output layers, but it should be the number that maximizes the accuracy of vehicle state estimation by the neural network. The number of elements in the output layer is determined by the output specifications for vehicle state estimation.

[0028] The neural network's machine learning is performed based on vehicle state variables (sprung speed, unsprung speed) data acquired in advance by a data acquisition vehicle, and behavioral information data including wheel speed. The data acquisition vehicle has the same specifications as the vehicle on which the vehicle state estimation unit 14 is installed, and is equipped with various sensors (wheel speed sensor, acceleration sensor, etc.) for acquiring vehicle state variables. In the neural network's machine learning, the weight parameters are adjusted to learn the correlation between the vehicle state variable (sprung speed, unsprung speed) data acquired by the data acquisition vehicle and the behavioral information data. The weight parameters obtained as a result of the learning are stored in the memory unit 12.

[0029] In the present embodiment, the vehicle state estimation unit 14 performs machine learning on the correlation between the data of the vehicle state quantities acquired by the data acquisition vehicle and the data of the behavior information. However, the present invention is not limited to this. For example, a vehicle model corresponding to the vehicle on which the vehicle state estimation unit 14 is mounted may be constructed, and the vehicle state estimation unit 14 may perform machine learning based on the data acquired by simulation using this vehicle model.

[0030] The vehicle state estimation unit 14 calculates the relative speed and relative displacement of each wheel based on the sprung speed and unsprung speed of each wheel output from the neural network. Specifically, the vehicle state estimation unit 14 calculates the relative speed based on the difference between the sprung speed and unsprung speed of each wheel. The vehicle state estimation unit 14 calculates the relative displacement by integrating the relative speed. The vehicle state estimation unit 14 calculates the pitch rate based on the sprung speed of the front wheels and the sprung speed of the rear wheels. The vehicle state estimation unit 14 determines, for example, whether the state of the road surface on which the vehicle travels is, for example, an ordinary road, a wavy road, or a bad road, by performing a calculation based on, for example, the sprung speed and unsprung speed.

[0031] In the present embodiment, the vehicle state estimation unit 14 estimates the sprung speed and the like of each wheel as vehicle state quantities from the behavior information including the wheel speed of each wheel using AI. However, the present invention is not limited to this. For example, the vehicle state estimation unit may calculate the sprung speed and the like of each wheel as vehicle state quantities from the behavior information including the wheel speed of each wheel based on a mathematical formula using a Kalman filter or the like.

[0032] The vehicle state estimation unit 14 estimates the sprung speed and unsprung speed of each wheel as vehicle state quantities from the behavior information including the wheel speed of each wheel using AI, and calculates the relative speed, relative displacement, pitch rate, etc. of each wheel based on these. However, the present invention is not limited to this. The vehicle state estimation unit 14 may estimate the relative speed, relative displacement, pitch rate, etc. in addition to the sprung speed and unsprung speed using AI.

[0033] As shown in Fig. 3, the damping force control unit 15 includes a handling stability control unit 16, a ride comfort control unit 17, a vehicle speed offset control current calculation unit 18, a speed bump / pothole control current calculation unit 19, and a damper command current arbitration unit 24. Note that the damping force control unit 15 does not necessarily need to include all of the handling stability control unit 16, the ride comfort control unit 17, and the vehicle speed offset control current calculation unit 18. The damping force control unit 15 may include, for example, only the handling stability control unit 16 or only the ride comfort control unit 17.

[0034] The handling stability control unit 16 calculates a control command value for improving the handling stability of the vehicle 1. Behavior information (for example, longitudinal acceleration, lateral acceleration, etc.) acquired from the CAN signal is input to the handling stability control unit 16, and the vehicle state quantity estimated by the vehicle state estimation unit 14 and the road surface determination result are also input. The handling stability control unit 16 calculates a command current value as a control command value based on this behavior information, vehicle state quantity, and road surface determination result. Specifically, for example, as the lateral acceleration increases, the handling stability control unit 16 calculates a control command value for roll suppression such that the damping force characteristic of the variable damper 7 becomes hard. The handling stability control unit 16 may calculate a control command value for suppressing dive / squat, not limited to roll suppression. Further, the handling stability control unit 16 may adjust the control command value based on the road surface determination result.

[0035] The ride comfort control unit 17 calculates a control command value for improving the ride comfort of the vehicle 1. The ride comfort control unit 17 calculates a control command value for controlling the damping force of the variable damper 7 of the suspension device 5 based on the vehicle state quantity (for example, sprung mass speed, relative speed) estimated by the vehicle state estimation unit 14. Specifically, for example, the ride comfort control unit 17 calculates a command current value as a control command value for improving the ride comfort of the vehicle 1 based on, for example, bilinear optimal control (BLQ control), skyhook control, H∞ control, etc.

[0036] The vehicle speed offset control current calculation unit 18 calculates a control current to adjust the damping force according to the vehicle speed. For example, when the vehicle speed rises above a predetermined speed, the vehicle speed offset control current calculation unit 18 outputs an offset value of the control command value to the damper command current arbitration unit 24 so that the damping force becomes harder as the vehicle speed increases.

[0037] The speed bump / pothole control current calculation unit 19 detects speed bumps and potholes based on behavioral information obtained from the CAN signal and calculates corresponding control current values. As shown in Figure 4, the speed bump / pothole control current calculation unit 19 includes a front wheel speed determination unit 20, a rear wheel speed determination unit 21, a speed bump control unit 22, and a pothole control unit 23. The speed bump / pothole control current calculation unit 19 executes the speed bump / pothole control process shown in Figure 5. The program for the speed bump / pothole control process is stored in the storage unit 12.

[0038] The front wheel speed determination unit 20 determines whether the change in front wheel speed is greater than the front wheel threshold. Specifically, as front wheel condition 1, the front wheel speed determination unit 20 determines whether the derivative of the front wheel speed (Vw(Fr)) (d / dt Vw(Fr)) is greater than the front wheel threshold A (A>0) when the derivative of the front wheel speed (Vw(Fr)) (d / dt Vw(Fr)) is a positive value (increasing change value). As front wheel condition 2, the front wheel speed determination unit 20 determines whether the derivative of the front wheel speed (d / dt Vw(Fr)) is less than the front wheel threshold B (B<0) when the derivative of the front wheel speed (d / dt Vw(Fr)) is a negative value (decreasing change value). The front wheel speed determination unit 20 determines that the road surface conditions for the front wheels have changed when either of the front wheel conditions 1 or 2 is met. The front wheel thresholds A and B are values ​​used to determine whether the front wheels have entered a location where the road surface conditions have changed, such as a speed bump or pothole, and are set appropriately according to the structure, specifications, etc., of the vehicle 1. The front wheel thresholds A and B are set, for example, based on the results of a vehicle driving test.

[0039] The rear wheel speed determination unit 21 determines whether the change in rear wheel speed is greater than the rear wheel threshold. Specifically, the rear wheel speed determination unit 21 determines the longitudinal acceleration Acc from the derivative of the rear wheel speed (Vw(Rr)) (d / dt Vw(Rr)) as rear wheel condition 1. x When the subtracted value is positive, it is determined whether the subtracted value has increased above the rear wheel threshold C (C > 0). The rear wheel speed determination unit 21 determines the longitudinal acceleration Acc from the derivative of the rear wheel speed (Vw(Rr)) (d / dt Vw(Rr)) as rear wheel condition 2. x When the subtracted value is negative, it is determined whether the subtracted value has decreased below the rear wheel threshold D (D > 0). The rear wheel thresholds C and D are values ​​that determine whether only the front wheels have entered a speed bump or pothole before the rear wheels have entered a place where the road surface conditions have changed, and are set appropriately according to the structure and specifications of the vehicle 1. The rear wheel thresholds C and D are set, for example, based on the results of vehicle driving tests.

[0040] The speed bump control unit 22 determines a speed bump when the front wheel speed determination unit 20 determines that the front wheel speed change is increasing or decreasing, and the rear wheel speed determination unit 21 determines that the rear wheel speed change determination result is increasing. Specifically, the speed bump control unit 22 determines a speed bump when the front wheel speed determination unit 20 determines that the road surface conditions for the front wheels have changed, and the rear wheel speed determination unit 21 determines that the rear wheel condition 1 is met. When the speed bump control unit 22 determines a speed bump, it outputs a speed bump command value. The speed bump command value is a command value for suppressing the full compression of the variable damper 7, and for example, it sets the damping force of the variable damper 7 to the hard side.

[0041] The pothole control unit 23 determines a pothole when the front wheel speed determination unit 20 determines that the front wheel speed change is increasing or decreasing, and the rear wheel speed determination unit 21 determines that the rear wheel speed change determination result is decreasing. Specifically, the pothole control unit 23 determines a pothole when the front wheel speed determination unit 20 determines that the road surface conditions for the front wheels have changed, and the rear wheel speed determination unit 21 determines that the rear wheel condition 2 is met. When the pothole control unit 23 determines a pothole, it outputs a pothole command value. The pothole command value is a command value for suppressing the full extension of the variable damper 7, and for example, it sets the damping force of the variable damper 7 to the hard side. The pothole command value and the speed bump command value may be the same value, but they may be different values ​​depending on the difference in control purpose.

[0042] The damper command current arbitration unit 24 is connected to the input side of the steering stability control unit 16, the ride comfort control unit 17, the vehicle speed offset control current calculation unit 18, and the speed bump / pothole control current calculation unit 19. Based on the control command values ​​(command current values) from the steering stability control unit 16 and the ride comfort control unit 17, the offset value from the vehicle speed offset control current calculation unit 18, and the control current values ​​(speed bump command value, pothole command value) from the speed bump / pothole control current calculation unit 19, the damper command current arbitration unit 24 calculates a command current as a control signal for damping force to be output to the damping force variable actuator 8 of each variable damper 7. The damping force variable actuator 8 of each variable damper 7 controls the damping force characteristics continuously or in multiple stages between hard and soft according to the command current, which is the drive current supplied from the damper command current arbitration unit 24.

[0043] Furthermore, the speed bump / pothole control current calculation unit 19 outputs a command for normal control (normal control command) when neither a speed bump nor a pothole occurs. In this case, the damper command current arbitration unit 24 calculates a command current as a damping force command signal to be output to the damping force variable actuator 8 of each variable damper 7, based on the control command values ​​from the steering stability control unit 16 and the ride comfort control unit 17, and the offset value from the vehicle speed offset control current calculation unit 18, in order to perform normal control.

[0044] Next, the speed bump / pothole control process by the speed bump / pothole control current calculation unit 19 will be described with reference to Figures 5 and 6. Note that each step in the flowchart shown in Figure 5 will be denoted as "S" (for example, step 1 will be "S1").

[0045] In S1, the speed bump / pothole control current calculation unit 19 acquires various data output from the receiving unit 13. At this time, the various data includes vehicle behavior information obtained from the CAN signal, and also includes information on the wheel speeds of the four wheels.

[0046] In the subsequent S2, the front wheel speed determination unit 20 determines whether either of the front wheel conditions 1 or 2 shown in Equation 1 below is met. Specifically, as front wheel condition 1, the front wheel speed determination unit 20 determines whether the front wheel speed derivative (d / dt Vw(Fr)) is greater than the front wheel threshold A when the front wheel speed derivative (d / dt Vw(Fr)) is a positive value (increasing change). As front wheel condition 2, the front wheel speed determination unit 20 determines whether the front wheel speed derivative (d / dt Vw(Fr)) is less than the front wheel threshold B when the front wheel speed derivative (d / dt Vw(Fr)) is a negative value (decreasing change).

[0047]

[0048] The front wheel speed determination unit 20 determines that the road surface conditions for the front wheels have changed when either front wheel condition 1 or 2 is met. In this case, it determines "YES" in S2 and proceeds to S3. On the other hand, the front wheel speed determination unit 20 determines that the road surface conditions for the front wheels have not changed when neither front wheel condition 1 or 2 is met. In this case, it determines "NO" in S2 and proceeds to S7. Also, if it determines "NO" in S5, it proceeds to S7.

[0049] In S7, since the road surface conditions do not correspond to either speed bumps or potholes, the speed bump / pothole control current calculation unit 19 outputs a normal control command for normal control and terminates processing.

[0050] When "NO" is determined in S2, the damping force control unit 15 calculates a command current based on the control command values ​​from the steering stability control unit 16 and the ride comfort control unit 17, and the offset value from the vehicle speed offset control current calculation unit 18. Based on this command current, the damping force control unit 15 controls the damping force characteristics of each variable damper 7.

[0051] In S3, the rear wheel speed determination unit 21 determines whether the rear wheel condition 1 shown in Equation 2 below is satisfied. Specifically, the rear wheel speed determination unit 21 determines the longitudinal acceleration Acc from the differential value of the rear wheel speed (d / dt Vw(Rr)) as the rear wheel condition 1. x When the subtracted value is positive, it is determined whether the subtracted value has increased above the rear wheel threshold C. If rear wheel condition 1 is met, the result is "YES" in S3 and the process moves to S4. On the other hand, if rear wheel condition 1 is not met, the result is "NO" in S3 and the process moves to S5.

[0052]

[0053] When the system determines "YES" in S3, either front wheel condition 1 or 2 is met, and rear wheel condition 1 is also met. Therefore, the speed bump control unit 22 determines that the front wheels of vehicle 1 have entered the speed bump and proceeds to S4. In S4, the speed bump control unit 22 outputs a speed bump command value for speed bump control. After that, the speed bump / pothole control process ends.

[0054] At this time, the damping force control unit 15 calculates a command current based on the speed bump command value, taking priority over control command values ​​from, for example, the steering stability control unit 16 and the ride comfort control unit 17. Based on this command current, the damping force control unit 15 controls each variable damper 7 so that its damping force characteristics are set to the hard side.

[0055] In S5, the rear wheel speed determination unit 21 determines whether the rear wheel condition 2 shown in Equation 3 below is satisfied. Specifically, the rear wheel speed determination unit 21 determines the longitudinal acceleration Acc from the differential value of the rear wheel speed (d / dt Vw(Rr)) as the rear wheel condition 2. x When the subtracted value is negative, it is determined whether the subtracted value has decreased below the rear wheel threshold D. If rear wheel condition 2 is met, the system determines "YES" in S5 and proceeds to S6. On the other hand, if rear wheel condition 2 is not met, the system determines "NO" in S5 and terminates the speed bump / pothole control process.

[0056]

[0057] When "NO" is determined in S5, the damping force control unit 15 calculates a command current based on the control command values ​​from the steering stability control unit 16 and the ride comfort control unit 17, and the offset value from the vehicle speed offset control current calculation unit 18. Based on this command current, the damping force control unit 15 controls the damping force characteristics of each variable damper 7.

[0058] In S6, either front wheel condition 1 or 2 is met, and rear wheel condition 2 is also met. Therefore, the pothole control unit 23 determines that vehicle 1 has entered a pothole and outputs a pothole command value for performing pothole control. After that, the speed bump / pothole control process ends.

[0059] At this time, the damping force control unit 15 calculates the command current based on the pothole command value, taking priority over control command values ​​from, for example, the steering stability control unit 16 and the ride comfort control unit 17. Based on this command current, the damping force control unit 15 controls each variable damper 7 so that its damping force characteristics are on the hard side.

[0060] Next, simulation experiments were conducted to simulate the case of a vehicle traveling over speed bumps and potholes. The results are shown in Figures 11 to 14. Figures 11 and 12 show the case of a vehicle traveling at 20 km / h entering a gentle protrusion (speed bump) with a height of 10 cm and a length of 1 m from a flat road. Figures 13 and 14 show the case of a vehicle traveling at 20 km / h entering a depression (pothole) with a depth of 10 cm and a length of 0.76 m from a flat road. Figure 11 shows a time chart of control command values, road surface judgment results, piston speed, wheel speed derivative value, and longitudinal acceleration of the vehicle body when the vehicle travels over a speed bump. Figure 13 shows a time chart of control command values, road surface judgment results, piston speed, wheel speed derivative value, and longitudinal acceleration of the vehicle body when the vehicle travels over a pothole.

[0061] Figures 11 and 13 also show control command values ​​according to a comparative example (for example, corresponding to the prior art described in Patent Document 1), in addition to the characteristics according to the present invention. In the comparative example, a control command value is output when the wheel speed is increasing and the differential value of the wheel speed exceeds a threshold.

[0062] First, let's consider the case where a vehicle travels over a speed bump, referring to Figures 11 and 12.

[0063] As shown in Figure 11, when the front wheels of vehicle 1 enter a speed bump, the derivative of the front wheel velocity (d / dt Vw(Fr)) increases above the front wheel threshold A. At this time, the longitudinal acceleration Acc of the vehicle body 2 x This decreases. In contrast, the front part of the vehicle body 2 rises as the front wheels ride up onto the speed bump (see Figure 7). At this time, the derivative of the rear wheel speed (d / dt Vw(Rr)) tends to increase (see Figure 12). Therefore, the longitudinal acceleration Acc is calculated from the derivative of the rear wheel speed (d / dt Vw(Rr)). x The subtracted value obtained by subtracting from the value becomes a positive value. When the subtracted value increases above the rear wheel threshold C, the controller 11 according to the present invention determines that it is a speed bump on the road surface and outputs a control command value (speed bump command value) corresponding to the speed bump. As shown in Figure 11, in this embodiment, control for speed bumps is started before the variable damper 7 changes from compression to extension.

[0064] On the other hand, in the comparative example as well, a control command value is output when the front wheel speed is increasing and the differential value of the wheel speed exceeds a threshold. Therefore, when the vehicle is traveling over a speed bump, there is no significant difference between the present invention and the comparative example.

[0065] Next, we will consider the case where a vehicle travels through a pothole, referring to Figures 13 and 14.

[0066] In the comparative example, a control command value is output when the front wheel speed is increasing and the differential value of the wheel speed exceeds a threshold. Thus, in the comparative example, the control command value is output based only on the front wheel speed, so the control command value is not output until the front wheel reaches the bottom of the pothole and the wheel speed switches to an increasing trend (see Figure 13). As a result, when the vehicle is driving through a pothole, the timing of outputting the control command value tends to be delayed.

[0067] In contrast, in this embodiment, potholes are identified based on the wheel speeds of the front and rear wheels. When the front wheels of vehicle 1 enter a pothole, the differential value of the front wheel speed (d / dt Vw(Fr)) decreases below the front wheel threshold B. At this time, the longitudinal acceleration Acc of the vehicle body 2 xIt slightly decreases. In contrast, when the front wheel falls into a pothole, the front part of the vehicle body 2 sinks (see Fig. 8). At this time, the wheel speed differential value (d / dt Vw(Rr)) of the rear wheel tends to decrease and significantly decreases compared to the longitudinal acceleration Acc x (see Fig. 13). Therefore, the subtraction value obtained by subtracting the longitudinal acceleration Acc x from the wheel speed differential value (d / dt Vw(Rr)) of the rear wheel becomes a negative value. And when the subtraction value decreases below the rear wheel threshold D, the controller 11 according to the present invention determines that the road surface is a pothole and outputs a control command value (pothole command value) corresponding to the pothole. That is, in the present embodiment, the control for the pothole is started before the tire completely falls into the depression (pothole). As a result, in the present embodiment, compared with the comparative example, the control for the pothole can be started at a timing about 50 ms earlier, for example.

[0068] Thus, the controller 11 according to the present embodiment includes a front wheel speed determination unit 20 that determines whether the value of the change in the front wheel speed is a front wheel speed change tendency greater than the front wheel threshold, a rear wheel speed determination unit 21 that determines whether the change in the rear wheel speed is a rear wheel speed change greater than the rear wheel threshold, a speed bump control unit 22 that determines that it is a speed bump and outputs a speed bump command value when the front wheel speed determination unit 20 determines that the change in the front wheel speed increases or decreases and the rear wheel speed determination unit 21 determines that the determination result of the change in the rear wheel speed is an increase, and a pothole control unit that determines that it is a pothole and outputs a pothole command value when the front wheel speed determination unit 20 determines that the change in the front wheel speed increases or decreases and the rear wheel speed determination unit 21 determines that the determination result of the change in the rear wheel speed is a decrease.

[0069] As shown in Figure 7, when vehicle 1 travels over a speed bump, the front wheels tend to increase in speed as they ride up onto the speed bump. Therefore, the control device shown in Patent Document 1 can also detect the speed bump and control the variable damper 7. However, as shown in Figure 8, when vehicle 1 travels over a pothole, the front wheel speed tends to decrease. Therefore, as shown in Figure 10, the control device shown in Patent Document 1 has the problem that it cannot properly control the variable damper 7 when vehicle 1 travels over a pothole. Also, as shown in Figure 9, when vehicle 1 enters a low-μ road from a high-μ road, the front wheel speed may increase, for example, depending on the specifications of vehicle 1. Therefore, the control device shown in Patent Document 1 may control the variable damper 7 when the vehicle enters a low-μ road in the same way as when a speed bump is detected.

[0070] In contrast, in this embodiment, the road surface condition is determined based on the change in front wheel speed (derivative value of wheel speed) and the change in rear wheel speed (derivative value of wheel speed). As shown in Figure 10, for example, when vehicle 1 travels over a speed bump, the front wheel speed derivative (d / dt Vw(Fr)) tends to increase significantly above the front wheel threshold A as the front wheel rides over the speed bump. On the other hand, as the front part of the vehicle body 2 rises when the front wheel rides over the speed bump, the rear wheel speed derivative (d / dt Vw(Rr)) tends to increase. At this time, the longitudinal acceleration Acc of the vehicle body 2 x This results in a change different from the derivative of the rear wheel speed (d / dt Vw(Rr)) (for example, a change in the opposite direction). Therefore, the speed bump control unit 22 adjusts the longitudinal acceleration Acc from the derivative of the rear wheel speed (d / dt Vw(Rr)) when the derivative of the front wheel speed (d / dt Vw(Fr)) increases significantly above the front wheel threshold A. xWhen the positive subtraction value obtained by subtracting a certain value increases significantly above the rear wheel threshold C, it is determined to be a speed bump, and a speed bump command value is output. As a result, the controller 11 can detect the vehicle 1 entering a speed bump early and control the damping force of the variable damper 7 to the hard side in accordance with the speed bump. This makes it possible to suppress the full compression of the variable damper 7 associated with speed bumps.

[0071] On the other hand, when vehicle 1 travels through a pothole, the front wheels fall into the pothole, causing the differential value of the front wheel speed (d / dt Vw(Fr)) to decrease significantly below the front wheel threshold B. Conversely, as the front of vehicle 2 descends due to the front wheels falling into the pothole, the differential value of the rear wheel speed (d / dt Vw(Rr)) tends to decrease. At this time, the longitudinal acceleration Acc of vehicle 2... x This changes differently from the derivative of the rear wheel speed (d / dt Vw(Rr)). Therefore, the pothole control unit 23 determines the longitudinal acceleration Acc from the derivative of the rear wheel speed (d / dt Vw(Fr)) when the derivative of the front wheel speed (d / dt Vw(Rr)) decreases significantly below the front wheel threshold B. x When the negative subtraction value obtained by subtracting the value decreases significantly below the rear wheel threshold D, it is determined to be a pothole, and a pothole command value is output. As a result, the controller 11 can determine early when the vehicle 1 enters a pothole and control the damping force of the variable damper 7 to the hard side according to the pothole. As a result, it is possible to suppress the full extension of the variable damper 7 associated with potholes.

[0072] In particular, in this embodiment, the pothole control unit 23 determines potholes based on the change in wheel speed of the front wheels (derivative value of wheel speed) and the change in wheel speed of the rear wheels (derivative value of wheel speed). Therefore, compared to the conventional technology, where the damping force is increased when it is determined that the wheel speed is increasing and the derivative value of the wheel speed has changed to an increasing direction beyond a predetermined threshold, potholes can be detected earlier. As a result, the variable damper 7 can be appropriately controlled when it changes in the direction of extension.

[0073] Furthermore, the rear wheel speed determination unit 21 uses the derivative value of the rear wheel speed (d / dt Vw(Rr)) and the longitudinal acceleration Acc of the vehicle body 2 to determine the rear wheel speed. x When the difference between the two is greater than the rear wheel thresholds C and D, it is determined that there is a change in rear wheel speed. When vehicle 1 enters a speed bump and a pothole, the front part of the vehicle body 2 rises or falls, and the derivative of the rear wheel speed (d / dt Vw(Rr)) changes. At this time, the longitudinal acceleration Acc of vehicle body 2 x The derivative of the rear wheel speed (d / dt Vw(Rr)) shows a different trend in change (for example, a trend in the opposite direction). Therefore, the rear wheel speed determination unit 21 uses the derivative of the rear wheel speed (d / dt Vw(Rr)) and the longitudinal acceleration Acc of the vehicle body 2 to determine the value of the rear wheel speed. x By determining the rear wheel speed change based on the difference between the two values, it is possible to detect the rear wheel speed change earlier and with higher accuracy compared to determining the rear wheel speed change using only the derivative of the rear wheel speed (d / dt Vw(Rr)). As a result, speed bumps and potholes can be detected early and accurately.

[0074] Furthermore, in this embodiment, speed bumps and potholes can be detected separately. Therefore, when the speed bump command value and the pothole command value are set to different values, the damping force of the variable damper 7 can be appropriately controlled according to the speed bumps and potholes.

[0075] In the first embodiment, the front wheel speed determination unit 20 determines the change in front wheel speed based on the differential value of the front wheel speed (d / dt Vw(Fr)), but the present invention is not limited to this. For example, the front wheel speed determination unit may determine the change in front wheel speed based on fluctuations in the front wheel speed.

[0076] In the first embodiment, the rear wheel speed determination unit 21 determines the differential value of the rear wheel speed (d / dt Vw(Rr)) and the longitudinal acceleration Acc of the vehicle body 2. x The rear wheel speed change is determined based on the difference between the two values. The present invention is not limited to this, and the rear wheel speed determination unit may determine the rear wheel speed change based on the differential value of the rear wheel speed or the wheel speed fluctuation.

[0077] Next, Figures 4 and 15 show a second embodiment. The characteristic of the second embodiment is that the front wheel threshold is an absolute value threshold. 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.

[0078] The speed bump / pothole control current calculation unit 31 according to the second embodiment is configured substantially the same as the speed bump / pothole control current calculation unit 19 according to the first embodiment. The speed bump / pothole control current calculation unit 31 detects speed bumps and potholes based on behavioral information acquired from the CAN signal and calculates control current values ​​corresponding to them. As shown in Figure 4, the speed bump / pothole control current calculation unit 31 includes a front wheel speed determination unit 32, a rear wheel speed determination unit 21, a speed bump control unit 22, and a pothole control unit 23.

[0079] The front wheel speed determination unit 32 in the second embodiment determines whether the change in front wheel speed is greater than the front wheel threshold. Specifically, the front wheel speed determination unit 32 determines whether the absolute value of the differential value of the front wheel speed (d / dt Vw(Fr)) is increasing above the front wheel threshold A (A>0). The front wheel speed determination unit 32 determines that the road surface conditions of the front wheel have changed when the absolute value of the differential value of the front wheel speed (d / dt Vw(Fr)) increases above the front wheel threshold A. The front wheel threshold A may be the same value as the front wheel threshold A in the first embodiment, or it may be a different value.

[0080] The speed bump control unit 22 determines that a speed bump has occurred when the front wheel speed determination unit 32 determines that the road surface conditions for the front wheels have changed, and the rear wheel speed determination unit 21 determines that the rear wheel condition 1 is met. When the speed bump control unit 22 determines that a speed bump has occurred, it outputs a speed bump command value.

[0081] The pothole control unit 23 determines that a pothole has occurred when the front wheel speed determination unit 32 determines that the road surface conditions for the front wheels have changed, and the rear wheel speed determination unit 21 determines that the rear wheel condition 2 is met. When the pothole control unit 23 determines that a pothole has occurred, it outputs a pothole command value.

[0082] Furthermore, the speed bump / pothole control current calculation unit 31 outputs a command for normal control (normal control command) when neither a speed bump nor a pothole is present. In this case, the damper command current arbitration unit 24 calculates a command current as a damping force command signal to be output to the damping force variable actuator 8 of each variable damper 7, based on the control command values ​​from the steering stability control unit 16 and the ride comfort control unit 17, and the offset value from the vehicle speed offset control current calculation unit 18, in order to perform normal control.

[0083] Next, with reference to Figure 15, the speed bump / pothole control process by the speed bump / pothole control current calculation unit 31 will be described.

[0084] The speed bump and pothole control process according to the second embodiment is the same as the speed bump and pothole control process according to the first embodiment. However, S11 is executed instead of S2. In S11, the front wheel speed determination unit 32 determines whether or not the following equation 4 is satisfied. Specifically, the front wheel speed determination unit 32 determines whether or not the absolute value of the differential value of the front wheel speed (d / dt Vw(Fr)) is greater than the front wheel threshold A (A>0).

[0085]

[0086] The front wheel speed determination unit 32 determines that the road surface conditions for the front wheels have changed when equation 4 is satisfied. In this case, it determines "YES" in S11 and proceeds to S3. On the other hand, the front wheel speed determination unit 32 determines that the road surface conditions for the front wheels have not changed when equation 4 is not satisfied. In this case, it determines "NO" in S11 and proceeds to S12. Also, if it determines "NO" in S5, it proceeds to S12.

[0087] In S12, since the road surface conditions do not correspond to either speed bumps or potholes, the speed bump / pothole control current calculation unit 31 outputs a normal control command for normal control and terminates processing.

[0088] Thus, in the second embodiment, substantially the same effects and advantages as in the first embodiment can be obtained. In the second embodiment, since the front wheel threshold A is an absolute value threshold, the determination process of the front wheel speed determination unit 32 can be simplified.

[0089] In the second embodiment, when the speed bump / pothole control process determines "NO" in S5 and S11, the process proceeds to S12, and the speed bump / pothole control current calculation unit 31 outputs a normal control command. The present invention is not limited to this, and, similar to the speed bump / pothole control process in the first embodiment, the speed bump / pothole control process may be terminated immediately when "NO" is determined in S5 and S11.

[0090] Next, Figures 4, 16, and 17 show a third embodiment. The characteristic of the third embodiment is that when it is determined that the road surface conditions for the front wheels have changed, and neither a speed bump nor a pothole is detected, a corresponding control command is output. 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.

[0091] The speed bump / pothole control current calculation unit 41 according to the third embodiment is configured substantially the same as the speed bump / pothole control current calculation unit 19 according to the first embodiment. The speed bump / pothole control current calculation unit 41 detects speed bumps and potholes based on behavioral information acquired from the CAN signal and calculates control current values ​​corresponding to them. As shown in Figure 4, the speed bump / pothole control current calculation unit 41 includes a front wheel speed determination unit 20, a rear wheel speed determination unit 21, a speed bump control unit 22, and a pothole control unit 23.

[0092] However, if the front wheel speed determination unit 20 determines that there has been a change in the road surface conditions for the front wheels, but the rear wheel speed determination unit 21 determines that the conditions for speed bumps and potholes (rear wheel conditions 1 and 2) are not met, the speed bump / pothole control current calculation unit 41 outputs a current command equivalent to a conventional passive damper (hereinafter referred to as a conventional damper equivalent current command).

[0093] Next, the speed bump / pothole control process by the speed bump / pothole control current calculation unit 41 will be described with reference to Figures 16 and 17.

[0094] The speed bump / pothole control process according to the third embodiment is the same as the speed bump / pothole control process according to the first embodiment. However, in S5, it is determined whether rear wheel condition 2 is met, and if it is determined to be "NO" in S5, the process proceeds to S21. At this time, although the front wheel speed determination unit 20 has determined that the road surface conditions of the front wheels have changed, the rear wheel speed determination unit 21 has determined that the speed bump and pothole conditions (rear wheel conditions 1 and 2) are not met. For this reason, the speed bump / pothole control current calculation unit 41 outputs a conveyor-equivalent current command and terminates the process. In this case, when the process in S21 is executed, the road surface conditions of the front wheels have changed. For this reason, the damping force control unit 15 sets the damping force of the variable dampers 7 of all wheels 3 to be equivalent to that of a conventional passive damper. This ensures that when the road surface conditions of the front wheels change, the ride comfort and handling stability of the vehicle 1 can be guaranteed even when it does not correspond to a speed bump or pothole.

[0095] Thus, the third embodiment can obtain substantially the same effects as the first embodiment. In the third embodiment, the speed bump / pothole control current calculation unit 41 outputs a conveyor-equivalent current command when it determines that the road surface conditions for the front wheels have changed and does not detect either speed bumps or potholes. As a result, when it is determined that the road surface conditions for the front wheels have changed but neither speed bumps nor potholes are detected, the damping force of the variable dampers 7 of all wheels 3 can be set to an amount equivalent to that of a conventional passive damper. As a result, when the road surface conditions for the front wheels change, even if it does not correspond to speed bumps or potholes, the ride comfort and handling stability of the vehicle 1 can be ensured.

[0096] In S21, the speed bump / pothole control current calculation unit 41 outputs a conveyor-equivalent current command. The present invention is not limited to this, and in S21, a hard current command may be output to set the damping force of the variable damper 7 to hard.

[0097] Next, Figures 18 to 20 show a fourth embodiment. The characteristic of the fourth embodiment is that it detects speed bumps and potholes based on changes in the front wheel speed. In the fourth embodiment, the same reference numerals are used for the same components as in the first and second embodiments described above, and their descriptions are omitted.

[0098] The speed bump / pothole control current calculation unit 51 according to the fourth embodiment detects speed bumps and potholes based on behavioral information acquired from the CAN signal and calculates control current values ​​corresponding to them. As shown in Figure 18, the speed bump / pothole control current calculation unit 51 includes a front wheel speed determination unit 52, a speed bump control unit 53, and a pothole control unit 54.

[0099] The front wheel speed determination unit 52 determines whether the change in front wheel speed is greater than the front wheel threshold. The front wheel speed determination unit 52 determines whether the following equation 5 is satisfied as front wheel condition 1. Specifically, as front wheel condition 1, the front wheel speed determination unit 52 determines whether the differential value of the front wheel speed (d / dt Vw(Fr)) is increasing above the front wheel threshold E (E>0) when the differential value of the front wheel speed (d / dt Vw(Fr)) is a positive value (increasing change value).

[0100]

[0101] The front wheel speed determination unit 52 determines whether the following equation 6 is satisfied as the front wheel condition 2. Specifically, the front wheel speed determination unit 52 determines whether the differential value of the front wheel speed (d / dt Vw(Fr)) is less than the front wheel threshold F (F < 0) when the differential value of the front wheel speed (d / dt Vw(Fr)) is a negative value (decreasing change value). The front wheel thresholds E and F are values ​​used to determine whether the front wheel has entered a place where the road surface conditions have changed, such as a speed bump or a pothole, and are set appropriately according to the structure, specifications, etc. of the vehicle 1. The front wheel thresholds E and F may be the same values ​​as the front wheel thresholds A and B in the first embodiment, or they may be different values.

[0102]

[0103] The speed bump control unit 53 determines a speed bump when the front wheel speed determination unit 52 determines that the change in front wheel speed is increasing. Specifically, the speed bump control unit 53 determines a speed bump when the front wheel speed determination unit 52 determines that the front wheel condition 1 is met. That is, the speed bump control unit 53 determines a speed bump when the differential value of the front wheel speed (d / dt Vw(Fr)) is a positive value and has increased above the front wheel threshold E. When the speed bump control unit 53 determines a speed bump, it outputs a speed bump command value.

[0104] The pothole control unit 54 determines that a pothole has occurred when the front wheel speed determination unit 52 determines that the change in front wheel speed is decreasing. Specifically, the pothole control unit 54 determines that a pothole has occurred when the front wheel speed determination unit 52 determines that the front wheel condition 2 is met. That is, the pothole control unit 54 determines that a pothole has occurred when the differential value of the front wheel speed (d / dt Vw(Fr)) is negative and has decreased below the front wheel threshold F. When the pothole control unit 54 determines that a pothole has occurred, it outputs a pothole command value.

[0105] Next, the speed bump / pothole control process by the speed bump / pothole control current calculation unit 51 will be described with reference to Figures 19 and 20.

[0106] In the speed bump / pothole control process according to the fourth embodiment, in S31 following S1, the front wheel speed determination unit 52 determines whether or not the front wheel condition 1 shown in Equation 5 is satisfied. Specifically, as front wheel condition 1, the front wheel speed determination unit 52 determines whether or not the front wheel speed derivative (d / dt Vw(Fr)) is greater than the front wheel threshold E when the front wheel speed derivative (d / dt Vw(Fr)) is a positive value (increasing change value).

[0107] When front wheel condition 1 is met, the speed bump control unit 53 determines that the front wheels of vehicle 1 are entering the speed bump. Therefore, if "YES" is determined in S31, the process proceeds to S4. In S4, the speed bump control unit 53 determines that vehicle 1 is entering the speed bump and outputs a speed bump command value for speed bump control. After that, the speed bump / pothole control process ends.

[0108] On the other hand, if the front wheel condition 1 is not met, the system determines "NO" in S31 and proceeds to S32. In S32, the front wheel speed determination unit 52 determines whether or not the front wheel condition 2 shown in Equation 6 is met. Specifically, as the front wheel condition 2, the front wheel speed determination unit 52 determines whether or not the front wheel speed derivative (d / dt Vw(Fr)) is less than the front wheel threshold F when the front wheel speed derivative (d / dt Vw(Fr)) is a negative value (increasing change value).

[0109] When front wheel condition 2 is met, the pothole control unit 54 determines that the front wheels of vehicle 1 have entered a pothole. Therefore, if "YES" is determined in S32, the process proceeds to S6. In S6, the pothole control unit 54 determines that vehicle 1 has entered a pothole and outputs a pothole command value for performing pothole control. After that, the speed bump / pothole control process ends.

[0110] On the other hand, the front wheel speed determination unit 52 determines that the road surface conditions for the front wheels have not changed if neither front wheel condition 1 nor 2 is met. In this case, it determines "NO" in S32 and proceeds to S12. In S12, since the road surface conditions do not correspond to either speed bumps or potholes, the speed bump / pothole control current calculation unit 31 outputs a normal control command for normal control and terminates processing.

[0111] Thus, in the fourth embodiment, speed bumps and potholes are detected based on the differential value of the front wheel speed (d / dt Vw(Fr)). For example, when vehicle 1 travels over a speed bump, the front wheel speed tends to increase as the front wheel rides up onto the speed bump. For this reason, the speed bump control unit 53 can detect a speed bump when the differential value of the front wheel speed (d / dt Vw(Fr)) is a positive value (increasing change value) and the differential value of the wheel speed (d / dt Vw(Fr)) is greater than the front wheel threshold E.

[0112] On the other hand, when vehicle 1 travels over a pothole, the front wheels tend to fall into the pothole, causing the front wheel speed to decrease. Therefore, the speed bump control unit 53 can detect a pothole when the differential value of the front wheel speed (d / dt Vw(Fr)) is negative (decreasing change value) and the differential value of the wheel speed (d / dt Vw(Fr)) is lower than the front wheel threshold F.

[0113] As a result, in the fourth embodiment as well, speed bumps and potholes can be detected separately, and the damping force of the variable damper 7 can be controlled according to the speed bumps and potholes.

[0114] Next, Figures 18, 21, and 22 show a fifth embodiment. The feature of the fifth embodiment is that it detects speed bumps and potholes based on the difference between the differential value of the front wheel speed and the longitudinal acceleration of the vehicle body. In the fifth embodiment, the same reference numerals are used for the same components as in the fourth embodiment described above, and their descriptions are omitted.

[0115] The speed bump / pothole control current calculation unit 61 according to the fifth embodiment is configured in substantially the same way as the speed bump / pothole control current calculation unit 51 according to the fourth embodiment. The speed bump / pothole control current calculation unit 61 detects speed bumps and potholes based on behavioral information acquired from the CAN signal and calculates control current values ​​corresponding to them. As shown in Figure 18, the speed bump / pothole control current calculation unit 61 includes a front wheel speed determination unit 62, a speed bump control unit 53, and a pothole control unit 54.

[0116] The front wheel speed determination unit 62 determines whether the change in front wheel speed is greater than the front wheel threshold. The front wheel speed determination unit 62 determines whether the equation shown in equation 7 below is satisfied as front wheel condition 1. Specifically, the front wheel speed determination unit 62 determines the longitudinal acceleration Acc from the differential value of the front wheel speed (d / dt Vw(Fr)) as front wheel condition 1. x When the subtracted value is positive, it is determined whether the subtracted value has increased above the front wheel threshold G (G > 0).

[0117]

[0118] The front wheel speed determination unit 62 determines whether the following equation 8 is satisfied as the front wheel condition 2. Specifically, the front wheel speed determination unit 62 determines the longitudinal acceleration Acc from the differential value of the front wheel speed (d / dt Vw(Fr)). xWhen the subtracted value is negative, it is determined whether the subtracted value has decreased below the front wheel threshold H (H < 0). The front wheel thresholds G and H are values ​​used to determine whether the front wheels have entered a place where the road surface conditions have changed, such as a speed bump or pothole, and are set appropriately according to the structure and specifications of the vehicle 1.

[0119]

[0120] The speed bump control unit 53 determines a speed bump when the front wheel speed determination unit 62 determines that the change in front wheel speed is increasing. Specifically, the speed bump control unit 53 determines a speed bump when the front wheel speed determination unit 62 determines that front wheel condition 1 is met. That is, the speed bump control unit 53 determines the longitudinal acceleration Acc from the differential value of the front wheel speed (d / dt Vw(Fr)). x A speed bump is determined when the subtracted value is positive and the subtracted value exceeds the front wheel threshold G. The speed bump control unit 53 outputs a speed bump command value when it determines that a speed bump has occurred.

[0121] The pothole control unit 54 determines a pothole when the front wheel speed determination unit 62 determines that the change in front wheel speed is decreasing. Specifically, the pothole control unit 54 determines a pothole when the front wheel speed determination unit 62 determines that the front wheel condition 2 is met. That is, the pothole control unit 54 determines the longitudinal acceleration Acc from the differential value of the front wheel speed (d / dt Vw(Fr)). x A pothole is determined when the subtracted value is negative and the subtracted value falls below the front wheel threshold H. When a pothole is determined, the pothole control unit 54 outputs a pothole command value.

[0122] Next, with reference to Figures 21 and 22, the speed bump / pothole control process by the speed bump / pothole control current calculation unit 61 will be described.

[0123] The speed bump and pothole control process according to the fifth embodiment is the same as the speed bump and pothole control process according to the fourth embodiment. However, in S41 following S1, the front wheel speed determination unit 62 determines whether or not the front wheel condition 1 shown in Equation 7 is satisfied. Specifically, the front wheel speed determination unit 62 determines the longitudinal acceleration Acc from the differential value of the front wheel speed (d / dt Vw(Fr)) as the front wheel condition 1. x When the subtracted value is a positive value, it is determined whether the subtracted value has increased above the front wheel threshold G.

[0124] When front wheel condition 1 is met, the system determines "YES" in S41 and proceeds to S4. In S4, the speed bump control unit 53 determines that vehicle 1 is entering a speed bump and outputs a speed bump command value for speed bump control. After that, the speed bump / pothole control process ends.

[0125] If front wheel condition 1 is not met, the system determines "NO" in S41 and proceeds to S42. In S42, the front wheel speed determination unit 62 determines whether or not front wheel condition 2, shown in equation 8, is met. Specifically, the front wheel speed determination unit 62 determines the longitudinal acceleration Acc from the differential value of the front wheel speed (d / dt Vw(Fr)) as front wheel condition 2. x When the subtracted value is negative, it is determined whether the subtracted value has decreased below the front wheel threshold H.

[0126] When front wheel condition 2 is met, the pothole control unit 54 determines that the front wheels of vehicle 1 have entered a pothole. Therefore, if "YES" is determined in S42, the process proceeds to S6. In S6, the pothole control unit 54 determines that vehicle 1 has entered a pothole and outputs a pothole command value for performing pothole control. After that, the speed bump / pothole control process ends.

[0127] On the other hand, the front wheel speed determination unit 62 determines that the road surface conditions for the front wheels have not changed if neither front wheel condition 1 nor 2 is met. In this case, it determines "NO" in S32 and proceeds to S12. In S12, since the road surface conditions do not correspond to either speed bumps or potholes, the speed bump / pothole control current calculation unit 61 outputs a normal control command for normal control and terminates processing.

[0128] Thus, the fifth embodiment can achieve substantially the same effects as the fourth embodiment. In the fifth embodiment, the front wheel speed determination unit 62 determines the differential value of the front wheel speed (d / dt Vw(Fr)) and the longitudinal acceleration Acc of the vehicle body 2. x When the difference between the two values ​​is greater than the front wheel thresholds A and B, it is determined that there is a change in front wheel speed. When vehicle 1 enters a speed bump or pothole, the differential value of the front wheel speed (d / dt Vw(Fr)) changes. At this time, the longitudinal acceleration Acc of vehicle body 2 x The differential value of the front wheel speed (d / dt Vw(Fr)) shows a different trend in change (for example, a trend in the opposite direction). Therefore, the front wheel speed determination unit 62 determines the longitudinal acceleration Acc of the vehicle body 2 based on the differential value of the front wheel speed (d / dt Vw(Fr)) and the longitudinal acceleration Acc of the vehicle body 2. x By determining the front wheel speed change based on the difference between the two values, it is possible to detect the front wheel speed change earlier and with higher accuracy compared to determining the front wheel speed change using only the differential value of the front wheel speed (d / dt Vw(Fr)). As a result, speed bumps and potholes can be detected early and accurately.

[0129] Next, Figures 23 and 24 show a sixth embodiment. The characteristic of the sixth embodiment is that the speed bump / pothole control current calculation unit further includes a slip determination unit that determines slip when the determination result of the front wheel speed determination unit is increasing or decreasing and the determination result of the rear wheel speed determination unit is 0. In the sixth embodiment, the same reference numerals are used for the same components as in the first embodiment described above, and their descriptions are omitted.

[0130] The speed bump / pothole control current calculation unit 71 according to the sixth embodiment is configured substantially the same as the speed bump / pothole control current calculation unit 19 according to the first embodiment. The speed bump / pothole control current calculation unit 71 detects speed bumps and potholes based on behavioral information obtained from the CAN signal and calculates control current values ​​corresponding to them. As shown in Figure 23, the speed bump / pothole control current calculation unit 71 includes a front wheel speed determination unit 20, a rear wheel speed determination unit 72, a speed bump control unit 22, and a pothole control unit 23.

[0131] The speed bump / pothole control current calculation unit 71 further includes a slip determination unit 73 that determines slippage when the determination result of the front wheel speed determination unit 20 is increasing or decreasing, and the determination result of the rear wheel speed determination unit 72 is 0.

[0132] At this time, the rear wheel speed determination unit 72 determines whether rear wheel conditions 1 and 2 are met, as well as whether rear wheel condition 3 shown in equation 9 below is met. Specifically, the rear wheel speed determination unit 72 determines whether the differential value of the rear wheel speed (d / dt Vw(Rr)) is approximately 0. At this time, whether the differential value of the wheel speed (d / dt Vw(Rr)) is approximately 0 is determined, for example, based on whether the absolute value of the differential value of the wheel speed (d / dt Vw(Rr)) is within a predetermined tolerance range that takes into account various errors due to detection, calculation, etc. At this time, the absolute value of the tolerance is set to a value smaller than the absolute values ​​of the rear wheel thresholds C and D.

[0133]

[0134] The slip detection unit 73 determines that a slip has occurred when the front wheel speed detection unit 20 determines that the road surface conditions for the front wheels have changed, and the rear wheel speed detection unit 72 determines that the rear wheel condition 3 is met. When the slip detection unit 73 determines that a slip has occurred, it outputs a slip control command.

[0135] Next, with reference to Figure 24, the speed bump / pothole control process by the speed bump / pothole control current calculation unit 71 will be described.

[0136] The speed bump / pothole control process according to the sixth embodiment is the same as the speed bump / pothole control process according to the first embodiment. However, if "NO" is determined in S5, the process proceeds to S51.

[0137] In S51, the rear wheel speed determination unit 72 determines whether or not the rear wheel condition 3 shown in Equation 9 is met. Specifically, the rear wheel speed determination unit 72 determines whether or not the derivative value of the rear wheel speed (d / dt Vw(Rr)) is approximately 0.

[0138] When equation 9 is satisfied in S51, the road surface conditions for the front wheels have changed, but the condition is neither a speed bump nor a pothole. That is, although the road surface conditions for the front wheels have changed, no pitch motion is occurring in the vehicle body 2. For this reason, the slip judgment unit 73 determines that slip is occurring in the front wheels. At this time, it determines "YES" in S51 and proceeds to S52.

[0139] In S52, the slip determination unit 73 outputs a slip control command for performing slip control. At this time, the vehicle 1 performs processes to suppress front wheel slip based on the slip control command (for example, front wheel traction control, ABS activation, etc.). After outputting the slip control command in S52, the speed bump / pothole control current calculation unit 71 terminates the speed bump / pothole control process. On the other hand, if equation 9 is not satisfied in S51, the system determines "NO" in S51 and terminates the process.

[0140] Thus, in the sixth embodiment, substantially the same effects and advantages as in the first embodiment can be obtained. In the sixth embodiment, the speed bump / pothole control current calculation unit 71 further includes a slip determination unit 73 that determines slip when the determination result of the front wheel speed determination unit 20 is increasing or decreasing and the determination result of the rear wheel speed determination unit 72 is 0. Therefore, the vehicle 1 can be controlled in accordance with the slip, and the ride comfort and handling stability of the vehicle 1 can be ensured.

[0141] In the embodiments described above, the differential value of the front wheel speed increased at speed bumps and decreased at potholes, but the present invention is not limited to this. For example, depending on the structure and specifications of the suspension system (variable damper), the differential value of the front wheel speed may decrease at speed bumps and increase at potholes. In this case, the controller, as a vehicle behavior control device, determines speed bumps and potholes in accordance with the increase and decrease in the differential value of the front wheel speed, taking into consideration the specifications of the suspension system.

[0142] In each of the above embodiments, the case in which a variable damper 7 consisting of a semi-active damper is used as the force generating mechanism was described as an example. 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 force generating mechanism. In each of the above embodiments, the case in which a force generating mechanism that generates an adjustable force between the vehicle body 2 and the wheel 3 is configured by a variable damper 7 consisting of a damping force adjustable hydraulic shock absorber was described as an example. The present invention is not limited to this, and for example, the force generating mechanism may be configured by an air suspension, stabilizer (Kinesus), electromagnetic suspension, etc., in addition to a hydraulic shock absorber.

[0143] In the embodiments described above, a control device for a suspension system used in a four-wheeled automobile was used as an example. However, the present invention is not limited to this, and may be applied to two-wheeled vehicles, three-wheeled vehicles, and also to work vehicles, transport vehicles such as trucks and buses.

[0144] The embodiments described above are illustrative, and it is possible to partially substitute or combine the configurations shown in different embodiments or modifications.

[0145] 1: Vehicle, 2: Body, 3: Wheels, 5: Suspension system, 7: Variable damper (force generation mechanism), 7A: Cylinder, 7B: Piston, 8: Variable damping actuator (damping force adjustment unit), 9: CAN, 11: Controller (vehicle behavior control device, control unit), 15: Damping force control unit, 16: Steering stability control unit, 17: Ride comfort control unit, 19, 31, 41, 51, 61, 71: Speed ​​bump / pothole control current calculation unit, 20, 32, 52, 62: Front wheel speed determination unit, 21, 72: Rear wheel speed determination unit, 22, 53: Speed ​​bump control unit, 23, 54: Pothole control unit, 24: Damper command current arbitration unit, 73: Slip determination unit

Claims

1. A vehicle behavior control device that controls a force generating mechanism provided between the vehicle body and the wheels and generating an adjustable force between the vehicle body and the wheels, comprising: a front wheel speed determination unit that determines whether the value of the change in front wheel speed is greater than a front wheel threshold; a rear wheel speed determination unit that determines whether the change in rear wheel speed is greater than a rear wheel threshold; a speed bump control unit that determines a speed bump and outputs a speed bump command value when the front wheel speed determination unit determines that the change in front wheel speed is increasing or decreasing, and the rear wheel speed determination unit determines that the result of the determination of the change in rear wheel speed is increasing; and a pothole control unit that determines a pothole and outputs a pothole command value when the front wheel speed determination unit determines that the change in front wheel speed is increasing or decreasing, and the rear wheel speed determination unit determines that the result of the determination of the change in rear wheel speed is decreasing.

2. The vehicle behavior control device according to claim 1, wherein the rear wheel speed determination unit determines that there is a change in the rear wheel speed when the difference between the differential value of the rear wheel speed and the longitudinal acceleration of the vehicle body is greater than the rear wheel threshold.

3. The vehicle behavior control device according to claim 1, wherein the front wheel threshold is an absolute value threshold.

4. The vehicle behavior control device according to claim 1, further comprising a slip determination unit that determines slippage when the determination result of the front wheel speed determination unit is increasing or decreasing and the determination result of the rear wheel speed determination unit is 0.

5. The vehicle behavior control device according to claim 1, wherein the speed bump command value and the pothole command value are command values ​​that are different from each other.

6. A vehicle behavior control device that controls a force generating mechanism provided between the vehicle body and the wheels and generating an adjustable force between the vehicle body and the wheels, comprising: a front wheel speed determination unit that determines whether the value of the change in front wheel speed is greater than a front wheel threshold value; a speed bump control unit that determines it is a speed bump and outputs a speed bump command value when the front wheel speed determination unit determines that the change in front wheel speed corresponds to either an increase or a decrease in speed, and a pothole control unit that determines it is a pothole and outputs a pothole command value when the front wheel speed determination unit determines that it corresponds to either an increase or a decrease in front wheel speed, and 7. A damper mounted on a vehicle and capable of adjusting damping force, the damper comprising: a bottomed cylindrical cylinder filled with working fluid; a piston dividing the inside of the cylinder into a first chamber and a second chamber; a damping force adjustment unit that adjusts the damping force by adjusting the flow of the working fluid; and a control unit that controls the amount of damping force adjustment, wherein the control unit comprises: a front wheel speed determination unit that determines whether the value of the change in front wheel speed is greater than a front wheel threshold; a rear wheel speed determination unit that determines whether the change in rear wheel speed is greater than a rear wheel threshold; and a speed bump control unit that determines a speed bump and outputs a speed bump command value when the front wheel speed determination unit determines that the change in front wheel speed is increasing or decreasing, and the rear wheel speed determination unit determines that the determination result of the change in rear wheel speed is increasing. A damper comprising: a front wheel speed determination unit that determines that the change in front wheel speed is increasing or decreasing, and a rear wheel speed determination unit that the result of the determination of the change in rear wheel speed is decreasing, determines that there is a pothole, and outputs a pothole command value.

8. A damper mounted on a vehicle and capable of adjusting damping force, the damper comprising: a bottomed cylindrical cylinder filled with working fluid; a piston dividing the inside of the cylinder into a first chamber and a second chamber; a damping force adjustment unit that adjusts the damping force by adjusting the flow of the working fluid; and a control unit that controls the amount of damping force adjustment, wherein the control unit comprises: a front wheel speed determination unit that determines whether the value of the change in front wheel speed is greater than a front wheel threshold; a speed bump control unit that determines it is a speed bump and outputs a speed bump command value when the front wheel speed determination unit determines that the change in front wheel speed corresponds to either an increase or a decrease in speed, and a pothole control unit that determines it is a pothole and outputs a pothole command value when the front wheel speed determination unit determines that it corresponds to either an increase or a decrease in front wheel speed, or the other.

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