JPH05278429A - Lateral acceleration detecting method for vehicle and active suspension device using such method - Google Patents

Abstract

PURPOSE:To detect the lateral acceleration of a vehicle which is one of control parameter of an active suspension of a vehicle by dividing into the transient disturbance lateral g and the revolving lateral g suitable for controlling the behavior of the vehicle. CONSTITUTION:A lateral g sensor (a) installed to a vehicle, and a revolving lateral g inferring means (d) to calculate the revolving lateral g from the car speed and the steering angle delta are provided, and a transient disturbance lateral g is found by subtrating the by-pass filter processed value of a logical revolving lateral g found by the revolving lateral g inferring means (d), from the by-pass filter processed value of the lateral g detecting value of the lateral g sensor (a), and the value obtained by subtrating the transient disturbance lateral g from the lateral g detecting value of the lateral sensor (a) is made into the revolving lateral g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle lateral acceleration detecting method and an active suspension device using the method.

[0002]

2. Description of the Related Art Various active suspension devices for detecting the stroke of a suspension (suspension stroke) and the lateral acceleration of a vehicle and controlling the vehicle posture (for example, roll posture) at the time of turning based on such information have been developed. JP-A-63-88514, JP-A-2-959
It is disclosed in the publication No. 11, etc.

In addition, active steering devices are being researched and developed to improve running safety by automatically steering to cancel changes in vehicle behavior due to disturbances such as side winds and road conditions.

A method of detecting a lateral acceleration (hereinafter referred to as lateral g) of a vehicle, which is one of control parameters in the active suspension device and the active steering device, is generally a lateral g sensor, a vehicle speed and a steering angle. There is a method of calculating from vehicle specifications.

[0005]

A lateral g sensor generally detects a lateral component of an inertial force acting on a mass, which is a main component of the sensor, by a lateral movement amount or a lateral pressing force of the mass, and the inertial force is detected. Since the lateral g is normally detected from the lateral component of the vehicle, not only the turning information of the vehicle but also the lateral wind or the road surface condition (wandering or nibbling) is detected in the lateral g sensor. The vehicle behavior information due to the external disturbance is included, and if the roll attitude control of the vehicle body is performed with the lateral g caused by the turning and the lateral g caused by the external disturbance, extra resonance occurs or the vehicle attitude changes to an unnatural one. This causes a less desirable phenomenon such as

On the other hand, in the method of calculating the lateral g by calculation from the vehicle speed, the steering angle, and the vehicle specifications, only the lateral g generated by turning can be obtained, but the lateral g can be calculated by the tire. Is only in the range where the side slip angle and the cornering force are in a linear relationship, and the turning lateral g outside the range cannot be accurately determined.

The present invention is particularly adapted to an active suspension device to accurately detect a transient disturbance that can prevent a sudden change in vehicle behavior, and also to show a gentle lateral g change with respect to a sudden disturbance. The main purpose is to detect g separately.

[0008]

According to the present invention, a turning lateral g estimating means for calculating a turning lateral acceleration of a vehicle body from a steering angle and a vehicle speed and a lateral acceleration from a lateral component of an inertial force acting on the vehicle body. In a vehicle having a lateral g sensor that emits a corresponding output, the high-pass filtered value of the theoretical lateral g calculated by the turning lateral g estimating means is subtracted from the high-pass filtered value of the lateral g detected value of the lateral g sensor. The first feature is to obtain the transient disturbance lateral g and subtract the transient disturbance lateral g from the lateral g detection value of the lateral g sensor to obtain the turning lateral g, and at least the suspension stroke change for each suspension. A feedback control system that controls the injection and discharge of fluid independently for each suspension to detect the amount and maintain the suspension at the standard vehicle height, and at least the lateral acceleration generated in the vehicle body. To predict the body roll during more turning,
In an active suspension system for a vehicle having a feedforward control system for injecting and discharging a fluid for each suspension so as to suppress a vehicle body roll as intended, a lateral turning g obtained by the method of the first characteristic is fed. A second feature is that a means for changing and controlling the feedback control system is provided to increase the control of the feedback control system by the transient lateral disturbance g, which is used as information on the vehicle body lateral acceleration of the forward control system.

[0009]

By detecting the transient disturbance lateral g and the turning lateral g by the method having the first characteristic, the lateral slip angle of the tire and the cornering force have a linear relationship, as well as a linear area. Even if there is a transient disturbance lateral g, the transient disturbance lateral g can be detected from the lateral g sensor output value.
Since the turning lateral g is calculated by subtracting from, the turning lateral g appears as a gentle lateral g change when a sudden disturbance lateral g occurs, and this causes the vehicle body roll controlled by the feedforward control system of the active suspension device. The changes will be gradual and natural. Further, as in the second characteristic configuration, by strengthening the control of the feedback control system of the active suspension device by the transient disturbance lateral g, the rolling of the vehicle body due to the disturbance is calmed down in a short time, which is very natural. With this, a vehicle body roll control that is comfortable to ride can be obtained.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

In the present invention, the lateral acceleration (hereinafter referred to as lateral g) is calculated from the lateral component of the inertial force attached to the vehicle body and acting on the vehicle body.
The lateral g of the vehicle body is calculated from a conventionally known lateral g sensor that produces an output corresponding to (1) and a steering angle signal detected by the steering angle sensor and a vehicle speed signal detected by the vehicle speed sensor.
The vehicle is equipped with an estimating means, and basically, from the two lateral g information detected by the lateral g sensor and the turning lateral g estimating means, respectively, a lateral g caused by a disturbance (disturbance lateral g) and a turning g The lateral g (turning lateral g) is detected separately, and more specifically, the change amount of the disturbance lateral g suitable for control of the active suspension device, that is, the transient lateral disturbance g and the turning lateral g, is detected. Each is to be detected.

It is when a disturbance suddenly occurs that the driver feels uncomfortable or disturbed by a disturbance such as a side wind. In such a case, the lateral g caused by the disturbance is detected and the vehicle behavior is detected. It is desirable that the control system such as the active suspension device be controlled so that the change (changes in path, yaw, roll, etc.) of (1) is gentle and small. However, if the driver does not feel uncomfortable or dangerous with respect to a gentle disturbance, the control system does not perform control, but the driver recognizes that a disturbance has occurred by a change in vehicle behavior. It is considered better to handle it yourself.

Therefore, in the present invention, basically, the transient disturbance lateral g and the turning lateral g are separately detected as shown in the block diagram of FIG. In FIG. 1, a lateral g waveform illustrates a case where a disturbance such as a lateral wind occurs after the lateral g is first generated by turning.

That is, the lateral g sensor a attached to the vehicle
When the turning lateral g is detected, it linearly rises and reaches a certain level. Then, when the lateral g further increases due to the influence of disturbance, the output of the lateral g sensor a also rises accordingly. If the output value of the lateral g sensor a including the disturbance is used as it is for the roll attitude control of the active suspension, as shown by the dotted line in FIG. 4, it is originally desired to reduce the roll angle, but the roll angle is set in the opposite direction. It will be controlled to increase. Therefore, the turning lateral g estimating means d calculates a theoretical turning lateral g without disturbance from the vehicle speed signal V detected by the vehicle speed sensor b and the steering angle signal δ detected by the steering angle sensor c, and this theoretical turning lateral g is calculated. g is passed through the first high-pass filter e to obtain the amount of change in the theoretical turning lateral g. Then, the output value of the lateral g sensor a is passed through a second high-pass filter f to obtain the amount of change, and the high-pass filtered value of the theoretical turning lateral g is subtracted from the high-pass filtered value of the lateral g sensor output value. To obtain the transient disturbance lateral g. Further, by subtracting the transient disturbance lateral g from the lateral g sensor output value, a turning lateral g in which a sudden disturbance lateral g input appears as a gentle lateral g change can be obtained.

When the active suspension is controlled using the turning lateral g thus obtained, even if a sudden disturbance lateral g occurs during the turning, it depends on the disturbance lateral g of the turning lateral g used for control. Even if the roll attitude control during running when the disturbance such as cross wind is large, the change in roll angle is small as shown by the solid line in Fig. 4 and stays near zero, and even if disturbance occurs, the active suspension control is performed. There is no adverse effect.

Generally, the theoretical turning lateral g is obtained by calculation from the vehicle speed V and the steering angle δ, and the lateral lateral g is calculated by subtracting the theoretical turning lateral g from the output value of the lateral g sensor. It is considered that the turning lateral g can be obtained by subtracting the disturbance lateral g from the output value. First, the theoretical turning lateral g can be accurately calculated by the calculation that the side slip angle of the tire and the cornering force are linear. If the slip angle of the tire is large, the calculation of the disturbance lateral g and the lateral turning g will not hold, and secondly, the lateral lateral g in which the lateral disturbance g is completely removed in this way is In g, the feed-forward control of the active suspension against the disturbance is not performed at all, which is not preferable as the active suspension for the purpose of vehicle behavior control. Therefore, as described above, if the lateral g sensor output value including the disturbance lateral g is used as it is to control the active suspension, an extra resonance occurs or an unnatural posture changes with respect to the sudden disturbance lateral g. A less favorable phenomenon occurs.

As shown in the embodiment of FIG. 1, the theory obtained by high-pass filtering the theoretical turning g from the change amount of the horizontal g-sensor output value obtained by high-pass filtering the output value of the horizontal g-sensor. By calculating the transient disturbance lateral g by subtracting the amount of change in the turning lateral g, the slip angle of the tire is large when the relationship between the tire side slip angle and the cornering force is in the linear region. Accurate detection of the transient disturbance lateral g is possible even in the region, and it is included in the lateral g sensor output value by subtracting the transient disturbance lateral g from the lateral g sensor output value to obtain the turning lateral g. The disturbance lateral g that is being changed becomes a gradual change, and the vehicle behavior control of the active suspension is performed gently to a sudden disturbance, which is a preferable response for the driver.

Next, an embodiment of an active suspension device to which the lateral g detection method of the present invention is applied will be described with reference to FIGS.
Will be described.

FIG. 2 is a system diagram showing an example of an active suspension control system to which the present invention is applied. In FIG. 2, 1a and 1b are left and right front wheel suspensions, and 1c and 1d are left and right rear wheel suspensions. As a suspension, an oil chamber A and a closed gas chamber B
And the oil chamber A of the gas spring portion D partitioned by the diaphragm C and the oil chamber F of the oil cylinder E are communicated with each other through the orifice G, and one end (for example, the bottom portion of the cylinder) of the oil cylinder E is connected to the suspension arm. The other end (for example, a piston rod) is connected to a vehicle body side member such as a wheel side member, and oil is applied to an orifice G between the inside of the oil cylinder and the oil chambers F and A of the gas spring portion against a vertical load.
A conventional known hydro-pneumatic suspension is adapted to generate a proper damping force by flowing through the diaphragm and to obtain a spring action by the volume elasticity of the gas sealed in the gas chamber B via the diaphragm C. The example adopted is shown.

2a, 2b, 2c and 2d supply oil to the oil chamber F (and the oil chamber A of the gas spring part) of the oil cylinder E of each suspension and discharge the oil from the oil chamber F (and A). These control valves 2a, 2b, 2c, 2d are controlled independently by a valve drive signal from a controller 3 described later.

An oil tank 4 and an oil pump 5 are rotatably driven by an engine 6. In the illustrated embodiment, the oil pump 5'for power steering and the oil pump 5 are tandem. An example is shown in which both oil pumps 5 and 5'are driven to rotate simultaneously by the engine 6.

The oil discharged from the oil pump 5 is accumulated in the high-pressure accumulator 8 through the check valve 7 and is switched to the injection side when one or more of the control valves is switched to the injection side. High-pressure oil is supplied from the control valve to the oil chamber of one or more suspensions, and when one or more of the control valves is switched to the discharge side, the control valve is switched to the discharge side. The oil in the oil chamber of one or more suspensions is discharged from the above and flows into the oil tank 4 through the oil cooler 9. Reference numeral 81 is a pressure sensor that detects the internal pressure of the high-pressure accumulator 8.

Reference numeral 10 is a relief valve, 11 is a load / unload valve, and the load / unload valve 11 is instructed by the controller 3 at the time of engine start to enter the unload state shown in the figure to reduce the load of engine start, It is switched to the load state when the start is completed.

The suspensions 1a, 1b, 1c,
1d is provided with an up / down g sensor 12 for detecting a vertical acceleration on the spring and a suspension stroke sensor 13 for detecting a vertical relative displacement between the sprung and the unsprung, that is, a change in extension / contraction stroke of the suspension. The detection signal of the suspension stroke sensor 13 is the controller 3
A front-rear g-sensor 14 for detecting the acceleration in the front-rear direction (front-rear g) of the vehicle body, and a lateral g-sensor for outputting an output corresponding to the lateral acceleration (lateral g) from the lateral component of the inertial force acting on the vehicle body. 15, a vehicle speed sensor 28, a steering angle sensor 29, and the like are provided, and detection signals of these are also input to the controller 3, and the controller 3 performs control as described below by inputting these signals.

Next, an embodiment of the control logic of the controller 3 will be described with reference to FIG.

In FIG. 3, a portion surrounded by a chain line is a control block diagram of a feedback control system for one of the front, rear, left and right suspensions, for example, the suspension 1a for the left front wheel, which is not shown in FIG. It has four sets of the same control logic as above, and controls each suspension independently.

When the vertical acceleration and the suspension stroke change are detected by the respective sensors 12 and 13 in the respective suspension parts, the high-frequency component of the vertical acceleration signal is reduced through the low-pass filter LPF, and the vertical acceleration signal is reduced to near zero through the dead zone circuit DZ ₁ . The signal in the set range is removed, and the gain G ₁ is multiplied to obtain the control instruction amount Q ₁ that matches the characteristics of the control valve.

The suspension stroke change signal is divided into two types, one passing through the differentiating circuit Dc and the other as it is, and the signal passing through the differentiating circuit Dc becomes a suspension stroke changing speed signal and is set near zero through the dead zone circuit DZ _2. The signal in the range is removed, and the gain G ₂ is further multiplied to obtain the control instruction amount Q ₂ matched with the control valve characteristic. For the suspension stroke change signal, read the state of the vehicle height adjustment switch 16 by the reference vehicle height signal generation circuit H. The actual suspension stroke change signal is obtained by taking the difference from the instructed reference vehicle height signal, the signal in the setting range near zero is removed through the dead zone circuit DZ ₃ , and the gain G ₃ is applied to the control instruction in accordance with the control valve characteristics. The quantity is Q ₃ .

A control instruction amount Q matched to the above-mentioned control valve characteristic
₁ , Q ₂ and Q ₃ are, for example, when the control valve is a flow control valve, the amount of oil to be injected or discharged in consideration of the valve opening / closing characteristics, the valve opening instruction time on the injection side or the discharge side of the control valve. Or, it means changing to the valve opening degree.

The above three control instruction quantities Q ₁ , Q ₂ and Q ₃ are added and converted into a correction instruction quantity Q in consideration of environmental conditions such as temperature and pressure loss due to the difference in pipe length through the control quantity correction circuit R, and the valve A control valve opening / closing signal is issued through the drive signal generating circuit W, the control valve 2a is switched to the injection side or the discharge side, and the suspension 1a is injected or discharged with an amount of oil as instructed.

In the above-mentioned control, the vertical acceleration control controls the discharge of oil in the suspension 1a for upward acceleration and the injection of oil in the suspension 1a for downward acceleration. Suspension characteristics that are soft and highly dampened by forces from below, such as thrusting up from the road surface, are injected and drained in a direction that maintains the vehicle height at the standard vehicle height for forces from above (that is, the vehicle body). It controls the suspension stroke change speed and controls the suspension stroke change to create a suspension characteristic that is apparently rigid so as to maintain the vehicle height. Also, the vertical acceleration signal is passed through a low pass filter LPF to unsprung. It does not respond much to vibrations in the high frequency range such as resonance, and control concentrates on vibrations in the low frequency range near the sprung resonance. Low-type ride that consumes energy, the control specifications of Baunjingu priority.

The vehicle height adjusting switch 16 is, for example, a changeover switch for switching from the normal vehicle height to the high vehicle height. When the normal vehicle height is selected, the reference vehicle height signal generation circuit H outputs a low reference vehicle height signal. And the vehicle height adjustment switch 16 is switched to the high vehicle height side, the reference vehicle height signal generation circuit H
Emits a high reference vehicle height signal, and the control by the suspension stroke change signal is a control to maintain the vehicle height at the reference vehicle height. Therefore, when the reference vehicle height is switched from the low normal reference vehicle height to the high reference vehicle height, According to the deviation from the target reference vehicle height, a control instruction amount Q ₃ for oil injection is issued to inject oil into the suspension 1a to raise the vehicle height to a height equal to the high reference vehicle height, and the vehicle height adjustment switch 16 is turned on. If the vehicle is returned to the normal vehicle height side, the oil discharge control instruction amount Q ₃ according to the deviation from the target reference vehicle height.
To discharge the oil in the suspension 1a to lower the vehicle height to the normal reference vehicle height. Oil is taken in and out by switching the vehicle height adjusting switch 16 at the same time for all suspensions.

The vehicle height adjusting switch 16 can also be used to change and adjust the vehicle height in a plurality of steps of three or more steps or in a stepless manner.

In addition to the above control in the feedforward control system, in order to perform accurate vehicle body posture control without delay when acceleration acts in the front-rear direction or the left-right direction such as during acceleration / deceleration and turning. A control logic of a feedforward control system based on the longitudinal g and the lateral g is provided.

That is, as shown in FIG.
The longitudinal acceleration signal detected in 4 is used for hysteresis 17,
The dead zone circuit 18 does not respond to a normal front-back g fluctuation during normal traveling, but converts the signal so as to act when there is a large pitching of the vehicle body such as full accelerator or moderate braking or more. It is input to the load movement amount calculation circuit 19. The front-rear load movement amount calculation circuit 19 calculates the front-rear load movement based on the input signal, the previously stored vehicle specifications, and the current ground height of the vehicle body center of gravity obtained from the vehicle height adjustment switch 16. The amount is calculated and the calculation result is output to the suspension reaction force increase calculation circuit 20. The suspension reaction force increase calculation circuit 20 uses the input information about the amount of load movement in the front-rear direction,
Depending on the type and drive type of each suspension (front-wheel drive type, rear-wheel drive type or four-wheel drive type, etc.), the amount of load movement at each suspension position taking into account the driving force and braking force applied to the tires Calculate the amount of increase or decrease in suspension reaction force for each suspension for each suspension.

The lateral g sensor 15, the vehicle speed sensor 28, the steering angle sensor 29, and the turning lateral g estimating means 30 are the lateral g sensors shown in FIG.
The sensor a, the vehicle speed sensor b, the steering angle sensor c, and the turning lateral g estimating means d correspond to the turning lateral g disturbance lateral g calculating circuit 31 shown in FIG.
The transient disturbance lateral g and the turning lateral g are separately calculated by the method described above.

That is, the lateral g detection signal detected by the lateral g sensor 15 is input to the turning lateral g disturbance lateral g calculation circuit 31. Further, the theoretical turning lateral g signal calculated by the turning lateral g estimating means 30 by a conventionally known calculation method by inputting the vehicle speed signal V and the steering angle signal δ detected by the vehicle speed sensor 28 and the steering angle sensor 29 is also the turning lateral g disturbance. It is input to the lateral g calculation circuit 31.

The turning lateral g disturbance lateral g calculating circuit 31 performs high-pass filter processing on each of the input lateral g detection signal and theoretical turning lateral g signal, and calculates the theoretical turning lateral g from the high-pass filtered values of the lateral g detection signal. The high-pass filtered value of the signal is subtracted to calculate the transient disturbance lateral g, and the transient disturbance lateral g is subtracted from the lateral g detection signal to calculate the turning lateral g. Then, the turning lateral g is prevented from reacting to a slight lateral g variation during normal traveling through the hysteresis circuit 21 and the dead zone circuit 22, and only a signal of a predetermined value or more is fed to the roll moment calculating circuit 2 of the feedforward control system.
3 and inputs the transient disturbance lateral g to the gain change instruction circuit 32.
Then, the gain change instruction circuit 32 issues a gain change instruction signal corresponding to the transient disturbance lateral g to increase the gains G ₁ , G ₂ and G ₃ of the feedback control system to prevent the rolling of the vehicle body due to the disturbance. The control quantities Q ₁ , Q ₂ , Q ₃ of the feedback control system for suppressing are strengthened.

The roll moment calculation circuit 23 stores the vehicle data preliminarily memorized from the signal of the lateral turning g input through the hysteresis circuit 21 and the dead zone circuit 22, and the vehicle weight center on the ground obtained from the vehicle height adjustment switch 16. The generated roll moment is calculated based on the height information, and the generated roll moment is distributed to the front and rear wheel moments in accordance with the target left / right load movement front / rear distribution ratio. The left / right load movement amount is calculated by the front / rear wheel left / right load movement amount distribution circuit 24 and output to the suspension reaction force increase calculation circuit 25. In the suspension reaction force increase calculation circuit 25,
The amount of increase / decrease in suspension reaction force is calculated in consideration of the load movement amount at each wheel, tire lateral force, vehicle height, suspension link type, etc.

The amount of increase / decrease in suspension reaction force based on the occurrence of front / rear g and the amount of increase / decrease in suspension reaction force based on the occurrence of lateral g calculated by the two suspension reaction force increase calculation circuits 20 and 25 are sent to the control amount calculation circuit 26. Input the two suspension reaction force increase / decrease values for each suspension to obtain the total suspension reaction force increase / decrease amount for each suspension, and adjust the suspension internal pressure (suspension gas Calculate the control amount of oil injection and discharge that should maintain the chamber internal pressure) for each suspension. The control amount is the control instruction amount Q ₄ for each suspension according to the valve specifications in the control amount conversion circuit 27 (for example, when the control valve is a flow control valve, the injection side or the discharge side in consideration of the valve opening / closing characteristics). Is converted to the valve opening instruction time of the above), and is added to the added value of the control instruction amounts Q ₁ , Q ₂ , Q ₃ for each suspension of the feedback control system, and these Q ₁ , Q ₂ , Q _3, the sum of Q ₄ and correction instruction amount Q through the control amount correction circuit R as described above, controls the injection or discharge of the oil issues a valve drive signal generating circuit W control valve opening and closing signals for each suspension To do.

Of the above controls, only the control of the vehicle body roll when the lateral g occurs will be described.

The turning lateral g disturbance lateral g calculating circuit 31 is a theoretical turning calculated by the turning lateral g estimating means 30 from the high-pass filtered value of the lateral g sensor detection value detected by the lateral g sensor 15 as described above. The value obtained by subtracting the high-pass filtered value of lateral g is taken as the transient disturbance lateral g, and the value obtained by subtracting this transient disturbance lateral g from the lateral g sensor detection value is taken as the turning lateral g. When the lateral g occurs, the turning lateral g used for control even if the disturbance lateral g is abrupt.
The disturbance lateral g appears as a gentle lateral g change,
The vehicle body roll control of the feedforward control system based on it also becomes gradual, and further, based on the transient disturbance lateral g, the gain change instruction circuit 32 sets the gains G ₁ , G ₂ , and G ₃ to be large and controls the feedback control system (basic Since the control to keep the vehicle height at the reference vehicle height is strengthened), the change in the vehicle body roll angle becomes small. Also, in the case of a gentle disturbance lateral g, the transient disturbance lateral g becomes zero or a minimum, and the vehicle body roll control of the feedforward control system will be performed at the lateral g sensor detection value or a turning lateral g close thereto, but the disturbance is originally Is gentle enough that the driver does not feel uncomfortable or dangerous, the roll control for the disturbance lateral g is also gentle and minimal, and the disturbance appears as a change in the vehicle behavior. In this case, the disturbance has occurred. It may appear as a change in vehicle behavior in the sense of making the driver recognize.

As described above, the feedforward control system is controlled by the turning lateral g obtained by the lateral g detecting method of the present invention, and the gain control of the feedback control system is carried out by the transient disturbance lateral g. A preferable vehicle body roll control is performed.

In the above, the body roll based on the disturbance can be minimized by increasing the gain of the feedback control system and intensifying the control of the feedback control system, but the rolling of the vehicle body due to the disturbance is accompanied by the disturbance. It is necessary to some extent in order for the driver to recognize that the vehicle is driving and to perform driving corresponding to it, and how much to suppress the roll is different depending on the driver's preference. It is desirable to configure so that can be adjusted within the range from the maximum value to zero. Even when the gain change amount is zero, the sudden disturbance lateral g
As a result, the vehicle body roll control of the feedforward control system is performed gently based on the turning lateral g that changes gently, and the rolling of the vehicle body is gently suppressed by the steady control of the feedback control system. The change in vehicle behavior can be suppressed within a range where the driver does not feel uncomfortable or dangerous.

Although the embodiment of FIG. 2 shows an example in which the present invention is applied to an active suspension using a hydropneumatic suspension, the present invention uses air or another gas as a spring, and the air or another gas is used. It can be applied to both flow control type and pressure control type active suspensions in which the body posture is controlled by injecting and discharging gas.

Further, the present invention is not limited to the device shown in FIG. 3, but for example, a feedforward control system is provided with a vehicle body roll setting means capable of setting a vehicle body roll direction and a roll degree at the time of turning the vehicle according to the driver's preference. (JP-A-2-124
No. 310), the amount of vertical relative displacement of at least the sprung and unsprung springs is detected for each suspension, and the injection and discharge of fluid is controlled independently for each suspension so as to maintain the suspension at the reference vehicle height. A feedback control system and a control that detects at least the lateral acceleration generated in the vehicle body and injects and discharges fluid independently for each suspension to maintain the roll of the vehicle body during turning as intended. It can be applied to all active suspensions of automobiles that have a feedforward control system that performs.

[0047]

As described above, according to the present invention, the transient disturbance lateral g and the turning lateral g suitable for the control of the active suspension system and the active steering system of the vehicle can be detected separately. The lateral g detection method according to the present invention is applied to an active suspension system for a vehicle having a feedback control system for keeping the vehicle height at a reference vehicle height and a feedforward control system for predicting and controlling the roll of the vehicle body based on the lateral g. As a result, since the signal of the turning lateral g accompanied by the gradual lateral g change is input to the feedforward control system in response to the sudden occurrence of the lateral lateral g, the vehicle lateral roll is rather increased by the control by the lateral lateral g. The conventional inconveniences such as the above are completely prevented, and by changing the control strength of the feedback control system with the signal of the transient disturbance lateral g, Rolling of the vehicle body based on the disturbance are those very short time also fit into mild, may provide the advantage that a very natural and ride comfortable vehicle body roll control obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a lateral g detection method according to the present invention.

FIG. 2 is an explanatory diagram of a fluid injection / exhaust system showing an example of an active suspension device to which the method of the present invention is applied.

FIG. 3 is a block diagram showing an embodiment of a control logic of the active suspension device shown in FIG.

FIG. 4 shows changes in the roll angle of the vehicle body when the active suspension control is performed with the turning lateral g obtained by the method of the present invention and when the active suspension control is performed with the lateral g sensor detection value including the disturbance lateral g. It is a figure to compare.

[Explanation of symbols]

 a lateral g sensor b vehicle speed sensor c steering angle sensor d turning lateral g estimation means e first high-pass filter f second high-pass filter 12 up / down g sensor 13 suspension stroke sensor 14 longitudinal g sensor 15 lateral g sensor 28 vehicle speed sensor 29 steering angle sensor 30 turning lateral g estimating means 31 turning lateral g disturbance lateral g calculating circuit 32 gain change instruction circuit

Claims (2)

[Claims] 1. A turning lateral g estimating means for calculating a lateral acceleration of a vehicle body from a steering angle and a vehicle speed, and a lateral g sensor for producing an output corresponding to the lateral acceleration from a lateral component of an inertial force acting on the vehicle body. In the vehicle having the above, the transient disturbance lateral g is obtained by subtracting the high-pass filtered value of the theoretical turning lateral g obtained by the turning lateral g estimation means from the high-pass filtered value of the lateral g detected value of the lateral g sensor, A lateral acceleration detection method for a vehicle, characterized in that the lateral lateral g is obtained by subtracting the transient lateral g from the lateral g sensor detection value. 2. A feedback control for independently injecting and ejecting a fluid for each suspension so as to detect at least vertical relative displacement of sprung and unsprung for each suspension and maintain the suspension at a reference vehicle height. System,
An active suspension device for a vehicle having at least a feedforward control system that predicts a vehicle body roll at the time of turning based on a lateral acceleration generated in the vehicle body and injects and discharges a fluid for each suspension to suppress the vehicle body roll as intended. In addition, the turning lateral g determined by the method described in claim 1 is used as lateral acceleration information of the feedforward control system, and the transient lateral lateral g determined by the method described in claim 1 is used for the feedback control system. An active suspension device for a vehicle, comprising means for changing and controlling the control strength of the vehicle.