JP2002192930A - Suspension control method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve both the steering stability of a vehicle and the riding comfort of an occupant by controlling an actuator that applies a force to a wheel in a vertical direction according to a running state of the vehicle. The present invention provides a suspension control method which can be performed. An actuator is provided on a wheel of a vehicle, and a method of controlling a suspension in which the wheel can receive a vertical force by the actuator. The method detects a vertical acceleration of a vehicle and determines a predetermined vertical acceleration value. In a case where the value is outside the value range and the state outside the predetermined value range continues for a predetermined time or more, control for suppressing vibration of the vehicle based on the detected vertical acceleration is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a suspension provided in a vehicle such as an automobile,
The present invention relates to a suspension control method provided with an actuator that applies a force to a wheel in a vertical direction.

[0002]

2. Description of the Related Art A suspension provided in a vehicle has a function of absorbing a shock from a road surface on which wheels are in contact with a ground to improve ride comfort, and generally includes a coil spring and a shock absorber for suppressing vibration of the coil spring. Have. Riding comfort tends to be good when the spring rate of the coil spring provided in the suspension is reduced and the spring is softened. On the other hand, the maneuverability of the vehicle is improved when the rigidity of the vehicle body is high.However, if the spring rate is reduced to improve the riding comfort, rolling tends to occur during turning of the vehicle, and pitching occurs during acceleration / deceleration. This makes the vehicle easier to handle and the maneuverability tends to decrease. As described above, it is generally difficult for a vehicle suspension to improve both maneuverability and ride comfort. Therefore, depending on the characteristics of the vehicle, the ride comfort or the maneuverability should be prioritized. Often set to either.

[0003] A stabilizer is conventionally known as one for increasing the roll rigidity of a vehicle body. The stabilizer has no function as a spring when the left and right wheels move in the same phase, but suppresses rolling by acting as a spring when the left and right wheels move up and down in opposite phases as in rolling. Since the stabilizer functions as a spring only when the left and right wheels move in opposite phases, it is possible to suppress rolling without increasing the spring rate of the coil spring.

[0004]

By the way, if the spring rate of the coil spring is reduced to improve ride comfort, rolling tends to occur at the time of turning, so that the diameter of the stabilizer bar must be increased or the portion where torsion occurs can be increased. It is necessary to increase the reaction force generated by the stabilizer bar by shortening the length.

[0005] However, when the reaction force generated by the stabilizer bar is increased, when the vehicle travels straight on a road surface having irregular irregularities, the result is equivalent to the case where the spring rate of the coil spring is increased, and the riding comfort tends to deteriorate. There is a problem. Further, the stabilizer only suppresses rolling, but cannot obtain the effect of suppressing pitching and bouncing.

[0006] The present invention has been made in view of such circumstances, and by controlling an actuator that applies a force to the wheels in a vertical direction according to the running state of the vehicle, the steering stability of the vehicle is improved. It is an object of the present invention to provide a suspension control method capable of improving both rideability and ride comfort.

[0007]

According to a first aspect of the present invention, an actuator (for example, the actuators 1L and 1R in the embodiment) is provided on a wheel of a vehicle, and the wheel receives a vertical force by the actuator. A control method for a suspension, wherein the control method detects a vertical acceleration of the vehicle and calculates a vertical acceleration value (for example, a vertical acceleration GB in the embodiment).
Is out of a predetermined value range (for example, a range from the threshold value Low to High in the embodiment), and the state outside the predetermined value range continues for a predetermined time (for example, the elapsed time threshold value T2 in the embodiment), It is characterized by performing control (for example, skyhook control in the embodiment) for damping the vibration of the vehicle based on the detected vertical acceleration.

According to the present invention, an actuator is provided on a wheel of a vehicle, and in a suspension in which the wheel can receive a vertical force by the actuator, the vertical acceleration of the vehicle is detected, and the vertical acceleration value is determined. It is a value outside the value range, and when the state outside the predetermined value range continues for a predetermined time or more, because the control for damping the vibration of the vehicle based on the detected vertical acceleration is performed,
When the change in the vertical acceleration is fast, it is possible to prevent the vibration suppression control of the vehicle body from being performed based on the detected vertical acceleration. As a result, it is possible to prevent the ride comfort from being deteriorated.

According to a second aspect of the present invention, an actuator (for example, the actuators 1L and 1R in the embodiment) is provided on a vehicle wheel, and the suspension is controlled by the actuator so that the wheel can receive a vertical force. In the method, the control method detects a vertical acceleration of the vehicle, and sets a vertical acceleration value (for example, a vertical acceleration GB in the embodiment) in a predetermined value range (for example, a range from a threshold value Low to a high value in the embodiment). )
And when the state within the predetermined value range continues for a predetermined time (e.g., the elapsed time threshold value T1 in the embodiment) or more, the control for damping the vibration of the vehicle based on the detected vertical acceleration (for example, , The skyhook control in the embodiment) is not performed.

According to the present invention, an actuator is provided on a wheel of a vehicle, and in a suspension in which the wheel can receive a vertical force, the vertical acceleration of the vehicle is detected, and the value of the vertical acceleration is determined. If the value within the value range and the state within the predetermined value range continues for a predetermined time or more, the control for suppressing the vibration of the vehicle based on the detected vertical acceleration is not performed, so that the An effect is obtained in that the vibration control of the vehicle body is not performed according to the change in acceleration, and the riding comfort on a road surface with a small stroke of the suspension can be improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is intended to achieve both steering stability and ride comfort by supplementing the spring rate of a spring in a suspension with the torque generated by an actuator according to the running state of a vehicle. At this time, the torque generated by the actuator is calculated based on the output of a sensor that detects the state of the vehicle body. As a result, the invention of the present application substantially increases the rigidity of the vehicle body and reduces the inclination of the vehicle body due to rolling or pitching in accordance with the running state of the vehicle, thereby obtaining the running stability of the vehicle, It is intended to improve comfort.

Further, if the spring rate of the spring is set to a large value from the beginning in order to increase the rigidity of the vehicle body, the vehicle body is directly subjected to the impact of the road surface condition, for example, the unevenness of the road surface, and the ride comfort is improved. It gets worse. However, according to the invention of the present application, the spring rate of the spring is set to a value that suppresses the impact due to the state of the road surface when traveling straight, and the spring rate to obtain the required vehicle body rigidity during cornering and acceleration / deceleration, and the spring rate of the spring Is compensated by the torque generated by the actuator,
Drivability and riding comfort can be improved.

An embodiment of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is a perspective view from the rear of a vehicle showing the structure of a suspension on the rear (rear wheel) side of a vehicle according to a first embodiment of the present invention. In the suspension of the left rear wheel in this figure, a knuckle 6L that rotatably supports the wheel WL is supported via an A-type upper arm 2L and a lower arm 3L so as to be vertically movable. The upper arm 2L is connected to an upper portion of the knuckle 6L via a joint provided at a distal end, and connected to the vehicle body B via a joint provided at a proximal end. Lower arm 3L
Is connected to the lower part of the knuckle 6L via a joint provided at the distal end, and is connected to the vehicle body B via a joint provided at the proximal end.
Connected to. The lower part of the spring 7L is supported at the center of the lower arm 3L, the upper part of the spring 7L is supported by the vehicle body B, and the link 5L and the drive arm 4 are provided at the base end of the lower arm 3L.
The actuator 1L is connected via L. Further, a shock absorber (not shown) is provided between the vehicle body B and the lower arm 3L. Here, the actuator 1L includes a speed reducer GL and a motor ML, and the torque generated by the motor ML is increased according to the speed reduction ratio of the speed reducer GL and is provided to the lower arm 3L.

Further, the structure of the right rear wheel suspension is the same, except that the suffixes of the above-mentioned components are changed from "L" to "R". The front portions of the knuckle 6L and the knuckle 6R are connected to each other by a stabilizer bar (not shown), and the vehicle body B is connected to the rear portions of the knuckle 6L and the knuckle 6R by lateral links (not shown).

With the above configuration, in the suspension of the left rear wheel, the vehicle body B moves up and down and rolls on the road surface by cornering, thereby forming the knuckle 6.
Lower arm 3L and upper arm 2L connected to L
Moves up and down from the base end connected to the vehicle body B as a starting point. As a result, the spring 7L and the shock absorber connected to the lower arm 3L expand and contract in accordance with the vertical movement, and the vertical movement of the vehicle body B with respect to the road surface is buffered. At this time, when the actuator 1L is driven to rotate the drive arm 4L around the rotation axis in the same direction as the rolling, the torque (N) that moves up and down to the lower arm 3L connected to the drive arm 4L via the link 5L. M) is transmitted and the spring 7
Complements the spring rate of L.

Similarly, in the suspension of the right rear wheel, the same operation as that of the suspension of the left rear wheel is performed only by changing the suffix of the above-mentioned component from “L” to “R”. Do. Accordingly, by controlling the actuators 1L and 1R provided on the wheel WL and the wheel WR in relation to each other, the spring rates of the springs 7L and 7R can be complemented, and the inclination of the vehicle body B due to rolling or pitching can be positively increased. Can be controlled.

That is, the suspension for the left rear wheel shown in FIG. 1 responds to the vertical movement of the vehicle body B due to cornering or the like, and when the spring 7L connected to the lower arm 3L expands and contracts, it responds to the amount of expansion and contraction. , A torque acting on the vehicle body B to correct the inclination of the vehicle body B. Hereinafter, for the sake of explanation, the torques applied to the lower arms 3L and 3R by the actuators 1L and 1R rotating the drive arms are referred to as torques TTL and TTR, respectively.

Here, referring to FIGS.
A sensor for detecting the state of the above will be described. FIG.
FIG. 2 is an explanatory diagram showing an arrangement of a stroke sensor attached to a vehicle body B for detecting a stroke amount of the suspension shown in FIG. 1. In this figure, reference numerals SL and SR are stroke sensors that detect and output the relative movement amount (stroke amount) between the vehicle body B and the lower arm 3L. The example shown in FIG. 16 is an example in which a stroke potentiometer is attached to the suspension of the left rear wheel as a stroke sensor SL. In the example shown here, the stroke sensor SL is attached to the vehicle body B, and is connected to the upper arm 2L by a link. The suspension for the right rear wheel is an example in which a rotary potentiometer is used as the stroke sensor SR, and detects the amount of movement of the upper arm 2R based on the rotation angle. Stroke sensor SL,
SR is not limited to a stroke-type or rotary-type potentiometer, and any sensor can be used as long as it can detect the stroke amount of the suspension.

That is, the stroke amount referred to here is:
Since it is a value corresponding to the displacement of the springs 7L and 7R, any sensor can be used as long as it can detect the displacement of each of the springs 7L and 7R. For example, the left and right stroke amounts corresponding to the acceleration applied in the lateral direction of the vehicle body B may be determined in advance, and the stroke amount may be determined by referring to the stroke amount determined in advance according to the acceleration detected by the acceleration sensor. Good.

FIG. 17 is a schematic diagram when the vehicle is viewed from above. In this figure, reference numeral SA denotes a steering angle sensor that detects and outputs a steering angle and a steering direction of the steering wheel 8. The output of the steering angle sensor SA outputs a numerical value with a sign. For example, when steering to the left, a positive numeric value corresponding to the steering angle is output, and when steering to the right, the steering angle is calculated. Outputs a negative number according to. Reference numeral SB denotes an acceleration sensor attached to the position of the center of gravity of the vehicle body B and detecting acceleration in the vertical direction (direction perpendicular to the road surface) of the vehicle body B. Reference sign SC is an acceleration sensor that is attached to a front position of the vehicle body B and detects and outputs acceleration in the front-rear direction of the vehicle body B. Reference numeral SD denotes an accelerator opening sensor that detects and outputs the opening of the accelerator. Sign SE
Is a tread force sensor that detects and outputs the tread force of the brake pedal. Symbol SF is a vehicle speed sensor that detects and outputs the speed of the vehicle.

The acceleration sensors for detecting the acceleration in the vertical direction of the vehicle body B may be attached to the left and right rear damper mounts of the vehicle body B as indicated by reference numerals SBL and SBR. When the acceleration sensors for detecting the acceleration in the vertical direction are attached to the positions of the left and right suspensions, the state of the vehicle body B can be detected in more detail.

The control of the above-mentioned actuators 1L and 1R, the stroke sensors SL and SR, and the steering angle sensor S
A, detection of the outputs of the acceleration sensor SB and the acceleration sensor SC is performed by a control unit (not shown). This control unit
It comprises a CPU and a storage unit such as a memory.
The PU controls the actuators 1L and 1R according to a program stored in the storage unit.

Next, referring to FIG. 2 to FIG.
The operation for controlling the suspension shown in FIG. FIG. 2 is a flowchart showing the main processing of the suspension control operation. First, the control unit detects the current state of the vehicle body B and calculates a target value required for performing control for suppressing rolling of the vehicle body B (step S).
1). The target value used in the following description is a target torque (TTL, TTR) generated by the actuators 1L, 1R and a rotation direction in which the torque is generated. In addition,
The processing in step S1 will be described later in detail with reference to FIGS.

Next, the control unit detects the state of the vehicle body B, and calculates a target value required for performing the skyhook control for improving the riding comfort when the vehicle is in a straight-ahead state (step). S2). The skyhook control is a control for damping the sprung (body B) vibration by an actuator based on the skyhook theory. The processing in step S2 will be described later in detail with reference to FIG.

Next, the control unit detects the current state of the vehicle body B and calculates a target value required for performing control for suppressing pitching of the vehicle body B (step S3).
The process in step S3 will be described later in detail with reference to FIG.

Next, the control unit determines a control mode according to the current state of the vehicle body B (step S4). The determination of the control mode is appropriate to perform any one of the above-described three controls (rolling suppression control, skyhook control, and pitching suppression control) for the suspension control at this time according to the state of the vehicle body B. That is, it is determined by determining whether or not there is. Here, the reason why the target values for performing the three controls are always calculated is to quickly respond to a change in the state of the vehicle.

Next, the control unit selects the target value calculated in steps S1, S2, and S3 based on the control mode determination result, obtains a current amount according to the target value, and obtains the motor ML, Output to MR (Step S
5). For example, when controlling the torque of the motors ML and MR by PWM (pulse width modulation) control, the control unit calculates the duty ratio of the width of the “H” level and the width of the “L” level in a constant cycle according to a target value. The motor M
The amount of current applied to L and MR is adjusted.

At this time, when increasing the current to increase the torque, the control unit increases the width of the “H” level, narrows the width of the “L” level, and decreases the current to reduce the torque. If it is desired, the duty ratio is calculated so that the width of the “L” level is widened and the width of the “H” level is narrowed. The direction in which the torque is generated depends on the motor M
Control is performed by reversing the direction of the current flowing through L and MR.
Hereinafter, for the sake of explanation, the spring 1
The current direction in which the torque TL is generated in the direction in which L is extended is defined as (+), and the current direction in which the actuator 1L generates the torque TL in the direction in which the spring 7L is contracted is defined as (-). Similarly, the actuator 1R controls the spring 7
The current direction in which the torque TR is generated in the direction in which R is extended is defined as (+), and the current direction in which the actuator 1R generates the torque TR in the direction in which the spring is compressed is defined as (-).

In FIG. 2, steps S1-S
Although the processing of step 3 is illustrated as being executed sequentially, the calculation of the three target values may be performed simultaneously and in parallel. By doing so, the cycle of executing the control operation shown in FIG. 2 can be shortened.

As described above, the suspension control is performed by selecting one of the rolling suppression control, the skyhook control and the pitching suppression control according to the state of the vehicle body B, so that the steering stability and the occupant's riding are controlled. It is possible to improve comfort together.

Next, with reference to FIGS. 3 to 5, the operation of calculating the target value when performing the rolling suppression control shown in step S1 of FIG. 2 will be described. 3 to 5 are flowcharts illustrating a process in which the control unit calculates a target value for controlling the actuators 1L and 1R. As a premise of the operation, when the driver gets into the vehicle and turns on the ignition switch, the control unit controls the measured value MD output by the stroke sensors SL and SR at this time.
L and MDR (unit mm) are stored in the storage unit as reference values DL and DR (unit mm), respectively. And the control unit includes:
According to the program, the processing of each flowchart shown in FIGS. The processing of these flowcharts is repeated as a set of processing at regular time intervals (for example, at every 10 msec), and the torques TTL, TT generated on the actuators 1L, 1R respectively from the obtained results.
Control of the occurrence of R is performed at regular intervals.

First, a process of calculating a target value based on the steering speed will be described with reference to FIG. By this processing, the torques TL and TR generated in the actuators 1L and 1R are obtained based on the steering speed. First, the control unit
The steering angle amount output by the steering angle sensor SA is read (step S11). Subsequently, the control unit determines a turning direction from the output value of the steering angle sensor SA (Step S12). Here, the turning direction indicates whether the steering wheel 8 is steered in the left or right direction from the neutral position, and is one of “right”, “neutral”, and “left”.

Next, the control unit performs an operation to obtain a change in the steering angle amount during the above-mentioned fixed time, that is, a steering angle speed (rad / s) as a differential value of the steering amount (step S1).
3). Subsequently, the control unit determines a steering angular velocity direction indicating the direction of the steering angular velocity based on the output value of the steering angle sensor (Step S14). This is for determining the steering state in detail according to the direction of the steering angular velocity. For example, the process of returning the steering wheel 8 from the left-turned state to the neutral position again cannot be determined only by the turning direction,
The direction of the steering angular velocity is required.

Next, the control unit obtains a target value corresponding to the steering angular velocity obtained in step S13 by referring to a target value map stored in the storage unit. FIG. 12 is an example of a target value map defining the relationship between the steering angular velocity and the torque generated in the actuators 1L and 1R. The control unit refers to the target value map, selects each of the torques TL and TR corresponding to the steering angular velocity, and outputs the selected torque as the calculation result. This output is passed to the processing described below (the processing shown in FIG. 5).

Next, with reference to FIG. 4, a description will be given of a process of calculating a target value (YL, YR) based on the stroke amount. First, the control unit reads the measured values MDL and MDR from the stroke sensors SL and SR, respectively (step S21).
Then, the control unit calculates a difference between the measured value and the reference value, that is, a stroke amount (Step S22). That is,
The control unit sets the stroke amount ΔDL of the left rear wheel to “MDL-D
L ”, and similarly, the stroke amount ΔDR of the right rear wheel is calculated by the equation“ MDR-DR ”, respectively, and is stored in the storage unit. By this calculation, the change amount of the stroke from the state where the ignition switch is turned on is obtained.

Next, the control unit calculates the stroke difference ΔLR between the stroke amount ΔDL of the left rear wheel and the stroke amount ΔDR of the right rear wheel obtained in step S22 as “ΔDL−ΔDR”.
(Step S23). Subsequently, the control unit determines the vehicle state based on the obtained stroke difference ΔLR (Step S24). When the stroke difference ΔLR = 0, the control unit determines that the vehicle body B is “neutral” with respect to the road surface, when the stroke amount ΔLR> 0, determines that the vehicle body B is “downward to the right”, and when the stroke difference ΔLR <0, It is determined to be “downward left”. This determination result is stored in the storage unit together with the stroke difference ΔLR as a vehicle state value.

Next, the controller calculates a target value by calculation based on the stroke difference ΔLR (step S2).
5). That is, the spring rate between the target spring rate JT (unit N (Newton) / mm) set according to the vehicle type and the basic spring rate JS (unit N (Newton) / mm) of the spring 7L actually provided on the suspension. The value obtained by multiplying the difference ΔJ by the stroke difference ΔLR (mm) is the roll stiffness reaction force shortage force FW. Therefore, the control unit:
An operation is performed based on the formula of “(JT−JS) × ΔLR”,
The roll stiffness reaction force shortage force FW is obtained. The torques TL and TR generated by the actuators 1L and 1R are
This is a torque required to supplement the insufficient spring rate difference ΔJ of the basic spring rate JS with respect to the target spring rate JT, and the lever ratio DD (substantially the drive arm 4L) Or 4R length,
(Unit: cm).

For this reason, the control unit sets “(FW × DD) /
The calculation is performed based on the equation (2) to obtain the torques YL and YR. Here, the reason why “FW × DD” is divided by “2” is that the torque required for complementing the roll rigidity (the apparent increase in the spring rate) is complementarily calculated by the actuator 1.
This is because L and 1R perform control to generate torques in opposite directions by "1/2" each.

Next, the control unit assigns a polarity to the previously obtained (FW × DD / 2) depending on whether the vehicle state value is “lower right” or “lower left,” Y
Calculate L and YR. The torques YL and YR obtained for this calculation become target values based on the stroke amount. For example, when the driver steers to the right and the vehicle body B rolls to the left, the control unit determines that the torque TL (+) for applying a reaction force in the direction in which the actuator 1L extends the spring 7L.
FW × DD / 2), while the actuator 1R
For applying a reaction force in the direction in which the spring 6R contracts.
R (−FW × DD / 2) is calculated. Hereinafter, for the sake of explanation, the torque in the direction in which the spring is extended is (+), and the torque in the direction in which the spring is contracted is (-).

Next, the control unit determines whether or not the vehicle state can be regarded as "neutral" based on the vehicle state value and the stroke difference ΔLR (step S26). This determination is for determining whether the stroke difference ΔLR is not “0”, but is an amount that can be regarded as substantially “0”. If the stroke difference ΔLR is within a predetermined range, the stroke difference is determined to be “0”. "0". As a result, the vehicle state can be regarded as "neutral" even if there is a slight stroke difference. If the result of this determination is that it cannot be regarded as "neutral", the control unit stores the values of the torques YL and YR obtained in step S25 in the storage unit, and ends the processing. On the other hand, when the vehicle state can be regarded as “neutral”, the control unit sets the vehicle state value to “neutral”,
Torque Y which is a target value based on the stroke obtained earlier
L and YR are set to “0” (step S27), stored in the storage unit, and the process ends.

Next, referring to FIG. 5, a target value (TL, TR) based on the steering angular velocity and a target value (Y
L, YR), the actuators 1L, 1
A process for obtaining a target value (torque TTL, TTR) to be generated in R will be described. First, the control unit determines whether the vehicle state value is “neutral” (step S31). If the determination result is “neutral”, the process proceeds to step S34, and the vehicle state is “neutral”. If not, the process proceeds to step S
Proceed to 32.

Next, based on the vehicle state value and the steering angular velocity direction, the control unit controls the roll direction of the vehicle body B (either the leftward downward direction RL or the rightward downward direction RR shown in FIG. 1) and the steering angular velocity. It is determined whether the directions match (Step S3)
2). Normally, the vehicle body B rolls in the direction opposite to the steering angle due to the centrifugal force generated at the time of turning. However, when fast steering is performed, the roll is generated with a certain timing delay after the start of the steering angle, so that the steering angular velocity direction may coincide with the roll direction. If the result of this determination is that the roll direction matches the steering angular velocity direction, only the target value based on the stroke amount is output. That is, the control unit outputs the torques YL and YR obtained from the stroke difference LR as target value torques TTL and TTR.

On the other hand, if the roll direction and the steering angular velocity direction do not match, a target value based on the steering angular velocity and a target value based on the stroke amount are added and output (step S3).
4). That is, the control unit calculates the torque TTL generated in the actuator 1L based on the equation “YL + TL”, calculates the torque TTR generated in the actuator 1R based on the equation “YR + TR”, and calculates the torque TTL obtained by this calculation. , TTR as the target torque.

Next, referring to FIG. 6, step S in FIG.
The operation of calculating the target value when performing the skyhook control shown in FIG. 2 will be described. First, the controller reads the vertical acceleration GB, which is the output of the acceleration sensor SB that detects the vertical acceleration of the vehicle body B (step S41). Subsequently, the control unit calculates a cancel value for canceling the DC offset included in the vertical acceleration GB (Step S42). This cancel value DC (k)
Is DC (k) = (0.75 / (0.75 + T)).
(Calculated by the formula DC (k-1) + GB (k) -GB (k-1), where T is the sampling time, G
B is the vertical acceleration, k means the latest value,
k-1 means the value used in the previous calculation process.

Next, the controller calculates the speed y (k) of the sprung portion (body B) (step S43). This speed y
(K) is y (k) = (1 / (1.3 + T)) · (1.
3y (k-1) + T.DC (k)). Here, T is the sampling time, and DC is the cancel value calculated in step S42. Also, k means the latest value, and k-1 means the value used in the previous calculation process.

Next, the control section determines the operating direction of the actuators 1L, 1R based on the value of the velocity y (k) calculated in step S43 (step S44).
In determining the operation direction, if the sprung speed y (k) is a positive value, the actuators 1L and 1R are contracted, and if the sprung speed y (k) is a negative value, the actuators 1L and 1R are extended.

Next, the controller calculates the target torques TTL and TTR based on the value of the sprung speed y (k) (step S45). The target values TTL and TTR are TT
L, TTR = | y (k) | · CK · K Here, C is a damping coefficient, and K is a torque constant.

Next, the control section makes a small acceleration determination, and replaces the target value based on the result of this determination (step S46).

The operation of the small acceleration determination will be described with reference to FIG. FIG. 7 is a flowchart illustrating the operation of step S46 shown in FIG. First, the control unit
It is determined whether the vertical acceleration GB obtained in step S41 is greater than a predetermined threshold value High (step S46a). If the result of this determination is that the vertical acceleration GB is greater than the threshold value High, step S4
Proceed to 6i.

On the other hand, the vertical acceleration GB is equal to the threshold value High.
If it is below, the control unit determines whether or not the vertical acceleration GB is greater than a predetermined threshold value Low (Step S46b). As a result of this determination, the vertical acceleration G
If B is greater than or equal to the threshold value Low, the process proceeds to step S46i.

The determination in steps S46a and S46b is a process for determining whether or not the vertical acceleration GB is in the range of not less than Low and not more than High. If not, the process proceeds to step S46i, and the process proceeds to step S46i. If so, the process proceeds to step S46c. Here, the threshold values High and Low are values having a vertical range with gravity acceleration (9.8 m / s ² ) as a neutral value.

Next, the control unit determines that the vertical acceleration GB is
If it is within the range, "0" is assigned to the counter ZGTIMC2 and reset (step S46c). Subsequently, the control unit determines whether or not the counter ZGTIMC1 is larger than the elapsed time threshold T1 (Step S46d). As a result of this determination, the counter ZGTIMC1 becomes equal to the elapsed time threshold T1.
If not more than (for example, 0.5 seconds), the control unit sets “1” to the flag KTFLG (step S46).
e). Then, the control section counts up the counter ZGTIMC1 (step S46f), and ends the process.

On the other hand, if the counter ZGTIMC1 is larger than the elapsed time threshold T1 in step S46d,
The control unit sets the target value to “0” in order to cut the outputs of the actuators 1L and 1R (Step S46g). Then, "0" is set to the flag KTFLG (step S46h), and the process ends.

Next, the processing when the vertical acceleration GB is out of the range of the threshold will be described. First, step S46
At i, the counter ZGTIMC1 is substituted by "0" and reset. Subsequently, the control unit sets the counter ZGTIM
It is determined whether C2 is greater than the elapsed time threshold T2 (for example, 1 second) (step S46j). If the result of this determination is that the counter ZGTIMC2 is greater than the elapsed time threshold T2, the control unit ends the process.

On the other hand, if the value of the counter ZGTIMC2 is equal to or smaller than the elapsed time threshold T2 in step S46j,
The control unit counts up the counter ZGTIMC2 (step S46k). Then, the control unit sets the flag KT
It is determined whether or not FLG is "1" (step S4).
6m). If the result of this determination is that the flag KTFLG is "1", the control unit process ends. If the flag KTFLG is not “1”, the control unit controls the actuator 1L, 1
The target value is set to "0" to cut the output of R (step S46n), and the process ends.

As described above, in the small acceleration determination process, when the change in the vertical acceleration is small compared to the steady state, the target value calculated based on the vertical acceleration GB is replaced with "0". This is a process for preventing a reaction force due to 1L and 1R from being generated. In addition, in the comparison processing between the count values of the counters ZGTIMC1 and ZGTIMC2 and the elapsed time thresholds T1 and T2, the elapsed time is obtained by multiplying the count value by a fixed time Te in which the processing shown in FIG. 7 is repeatedly executed. The comparison process is performed.

Here, the operation shown in FIG. 7 will be described with reference to FIG. FIG. 18A illustrates the operation when the value of the vertical acceleration sensor changes from outside the threshold range (the range from Low to High) to the range. In the diagram shown in FIG. 18A, the y-axis indicates the output value of the vertical acceleration sensor, and the x-axis indicates time. As shown in this figure, until the time t1, the output value of the vertical acceleration sensor is larger than the threshold value High, so that the target value is calculated based on the output value of the vertical acceleration sensor and the actuator 1
A reaction force is generated at L and 1R.

Next, at time t1, when the sensor output value changes from outside the threshold range to within the threshold range, the elapsed time from time t1 is measured. Then, even if the sensor output value exceeds the elapsed time threshold value T1, it is within the threshold range (FIG. 18).
(Solid line shown in (a)), the target value is set to “0”. On the other hand, if the sensor output value changes again outside the threshold value range before the elapsed time threshold value T1 is exceeded (the dotted line shown in FIG. 18A),
Using the calculated target value as it is, the actuator 1L,
A reaction force is generated at 1R.

FIG. 18B is a diagram for explaining the operation when the value of the vertical acceleration sensor changes from within the threshold range to outside the threshold range. In the diagram shown in FIG. 18B, the y-axis indicates the output value of the vertical acceleration sensor, and the x-axis indicates time. As shown in this figure, since the output value of the vertical acceleration sensor is within the threshold range until time t2, the target value is "0" and no reaction force is generated in the actuators 1L and 1R.

Next, when the sensor output value changes from within the threshold range to outside the range at time t2, the elapsed time from time t2 is measured. Then, even if the sensor output value exceeds the elapsed time threshold value T2, it is outside the threshold range (FIG. 18).
(Solid line shown in (b)), the reaction force is generated in the actuators 1L, 1R using the calculated target value as it is.
On the other hand, if the sensor output value again falls within the threshold range before the elapsed time threshold T2 is exceeded (the dotted line shown in FIG. 18B), the target value is maintained at “0” and the actuators 1L, 1R To avoid generating a reaction force.

By such an operation, the value within the threshold range (L
If the sensor output value changes only within the range from ow to High) and the elapsed time exceeds the elapsed time threshold T1, the actuator 1
It is possible to prevent a reaction force from being generated in L and 1R. When the elapsed time from the inside of the threshold range to the outside of the range and then back to the inside of the range is shorter than the elapsed time threshold T2, a reaction force is generated in the actuators 1L and 1R assuming the vertical acceleration of the high frequency component. It becomes possible not to make it do.

Next, referring to FIG. 8, step S in FIG.
The operation of calculating the target value when performing the pitching suppression control shown in FIG. 3 will be described. First, the control unit reads the longitudinal acceleration GC, which is the output value of the acceleration sensor SC that detects the longitudinal acceleration of the vehicle body B (step S51). Then, the control unit determines the direction of the reaction force generated by the actuators 1L and 1R based on the read longitudinal acceleration GC (step S52). The direction of this reaction force is the longitudinal acceleration G
It is determined by determining whether the vehicle is accelerating or decelerating based on the value of C. When the vehicle is accelerating, since the load moves rearward, the springs 7L and 7R of the rear wheels are used.
Shrinks. On the other hand, during deceleration, since the load moves forward, the rear wheel springs 7L and 7R extend. Therefore, when it is determined that the vehicle is accelerating, the direction in which the reaction force is generated is the direction in which the springs 7L and 7R are extended. On the other hand, when it is determined that the vehicle is decelerating, the direction in which the reaction force is generated is the direction in which the springs 7L and 7R are compressed. And

Next, the control unit calculates the movement amount of the load moved by the acceleration / deceleration (step S53). The load movement amount ΔW is given by ΔW = (1/2) · (hg / L) · W · Xg
It is calculated by the following equation. Here, hg is the height of the center of gravity of the vehicle, L is the wheelbase of the vehicle, W is the weight of the vehicle, and Xg is the absolute value of the longitudinal acceleration GC. Subsequently, the control unit calculates and outputs a target value TTL per actuator (step S54). The reaction force of the load movement amount ΔW is 2
The target value torques TTL, TTR
Is obtained by the equation of TTL, TTR = ΔW / 2.

Next, referring to FIG. 9, step S in FIG.
The operation for performing the control mode determination shown in FIG. 4 will be described. First,
The control unit reads the sensor output value (Step S6)
1). The sensor output value read here is obtained during the processing operation for obtaining the target value described above, and the output value stored in the storage unit is read. The control unit determines that the absolute value of the steering angle is 5
(°) is determined (step S6)
2). If the result of this determination is greater than 5 (°), it is determined that the vehicle is turning, and a target value for the rolling suppression control is selected (step S63).

Next, the control unit multiplies the selected target value by a gain obtained based on the current vehicle speed (step S64). The gain for multiplying this target value is shown in FIG.
Is obtained with reference to a gain map defining the relationship between the vehicle speed and the gain shown in FIG. As shown in FIG. 13, the gain map is
The X-axis is the vehicle speed, and the Y-axis is the gain. The gain has a value of “0” to “1”. In the example shown here, the gain is “0” when the vehicle speed is 0 to 10 (Km / h),
The gain is “1” for 20 (Km / h) or more.
Linear interpolation is performed between 0 and 20 (Km / h). Therefore, while the vehicle speed is 0 to 10 (Km / h), the control by the actuators 1L and 1R is not performed, and the control is performed at 20 (Km / h).
h) The above means that control is performed according to the target value set in step S63. As described above, by multiplying the target value by the gain, the target value can be changed in accordance with the speed of the vehicle. Therefore, at a low speed of 10 (Km / h) or less, the target value may be varied. Due to the influence, it is possible to prevent a minute control operation from being performed and to reduce the ride comfort.

Next, in step S62, if the absolute value of the steering angle is not more than 5 (°), the control unit determines whether or not the absolute value of the steering angle speed is greater than 0.5 (rad / s). (Step S65). If the absolute value of the steering angular speed is greater than 0.5 (rad / s) as a result of this determination, it is determined that the possibility of rolling is high because the steering angle is small but the steering angular speed is high, and the process proceeds to step S63. Then, the above-described processing is performed. On the other hand, the absolute value of the steering angular velocity is 0.5
If not more than (rad / s), the control unit further determines whether or not the absolute value of the longitudinal acceleration is greater than 2 (m / s ² ) (step S66). If the result of this determination indicates that the absolute value of the longitudinal acceleration is 2 (m / s ² ) or less, the control unit selects a target value for skyhook control (step S6).
7), the process proceeds to step S64, and the obtained target value is multiplied by a gain based on the vehicle speed. If the result of the determination in step S66 indicates that the absolute value of the longitudinal acceleration is greater than 2 (m / s ² ), the control unit selects a target value for pitching suppression control (step S68). When the target value of the pitching suppression control is selected, the control unit does not perform the multiplication of the gain based on the vehicle speed (Step S64). This is because it detects whether or not the longitudinal acceleration at which pitching is likely to occur is equal to or greater than a predetermined value, and determines the pitching suppression control based on the absolute value of the longitudinal acceleration. This is because no multiplication is required.

As described above, based on the output value of the sensor provided in the vehicle, the state of the vehicle body B is determined based on whether a predetermined condition is satisfied, and as a result of this determination, the vehicle is in a turning state. When it is determined that the suspension is controlled to suppress rolling, it is possible to obtain the same effect as when the spring rate of the suspension is increased only during turning. Also,
As a result of the determination, when it is determined that the vehicle is in a straight-ahead state, the suspension is mainly controlled to suppress bouncing so that the riding comfort is improved. Can be obtained with the same effect as when. Furthermore, as a result of the determination, when it is determined that the vehicle is in a straight-ahead state and is in an acceleration / deceleration state, control for mainly suppressing pitching is performed, so that it is equivalent to a case where the spring rate of the suspension is increased only during acceleration / deceleration. The effect can be obtained.

<Second Embodiment> Next, a second embodiment will be described with reference to FIGS. FIG.
6 is a flowchart showing a processing operation of calculating a target value without using an output of a longitudinal acceleration sensor in a process of calculating a target value used for pitching suppression control shown in FIG. FIG. 11 is a diagram illustrating only a portion different from the control mode determination process illustrated in FIG. 9 when a target value is obtained by the process illustrated in FIG. First, the control unit reads the output value of the accelerator opening sensor SD (Step S71). Subsequently, the control unit reads the output value of the pedaling force sensor SE (Step S72). Then, the control unit controls the accelerator opening sensor S
It is determined whether or not there is an output at D (step S7)
3). If the result of this determination is that there is an output from the accelerator opening sensor SD, the control unit obtains a target value according to the accelerator opening with reference to the target value map (step S74).
FIG. 14 shows a target value map for obtaining a target value corresponding to the accelerator opening.

If the result of determination in step S73 is that there is no output from accelerator opening sensor SD, the control unit determines whether or not there has been output from pedal force sensor SE (step S7).
5). If the result of this determination is that there is an output from the pedaling force sensor SE, the control unit obtains a target value corresponding to the brake pedaling force with reference to the target value map (step S76). FIG. 15 shows a target value map for obtaining a target value according to the brake depression force. On the other hand, when there is no output from the pedaling force sensor SE, the control unit sets the target value to “0” (Step S77).

Next, a control mode determination process according to the second embodiment will be described with reference to FIG. FIG. 11 is a flowchart showing only processing portions corresponding to steps S65 to S68 shown in FIG. In this figure,
The operations in steps S65, S67, and S68 are the same as the processes shown in FIG. 11 is different from FIG. 9 in that steps S66A and S6 are used instead of step S66.
6B is provided.

If the absolute value of the steering angular velocity is equal to or less than 0.5 (rad / s) in step S65, the control unit
It is determined whether or not the accelerator opening is equal to or less than 10 (°) (step S66A). If the result of this determination is that the accelerator opening is greater than 10 (°), the flow proceeds to step S68,
If the accelerator opening is equal to or less than 10 (°), the control unit determines whether the pedaling force is equal to or less than 20 (N, Newton) (Step S66B). As a result of this determination, the pedaling force is 20
If it is larger than (N), the process proceeds to step S68, and if the pedaling force is 20 (N) or less, the process proceeds to step S67.

As described above, since the acceleration / deceleration is determined based on the accelerator opening and the brake depression force without using the longitudinal acceleration sensor, disturbance from the road surface and disturbance due to the road surface gradient can be eliminated. As a result, the state determination process can be simplified, and fine control can be performed.

In the above description, the example in which the actuators 1L and 1R are provided on the rear wheels of the automobile has been described. However, the suspensions of the front wheels are also provided with the actuators so that the above-described control is performed. You may. Further, all the suspensions of the rear wheels and the front wheels may be provided with the actuators to control each of the four wheels.

As described above, it is determined whether the vehicle is in a turning state or a straight traveling state in accordance with the state of the vehicle. If the vehicle is in the turning state, the opposite phase control is performed on the left and right wheels. Therefore, when the vehicle is in a straight running state, the in-phase control is performed on the left and right wheels to mainly suppress bouncing, so that the steering stability is improved and the occupant's riding comfort is improved. It can be improved.

Further, even in a straight-ahead state, during acceleration and deceleration, right and left in-phase control is performed to mainly suppress pitching, so that when accelerating, the force lifting the rear of the vehicle is a reaction force on the road surface. , The load on the ground increases, the grip force of the tire can be increased, and acceleration can be performed efficiently. In addition, during deceleration, the sinking behind the vehicle can be reduced, so that a change in the behavior of the vehicle can be reduced.

[0076]

As described above, according to the first aspect of the present invention, an actuator is provided on a wheel of a vehicle, and the suspension is capable of receiving a vertical force by the actuator. If the vertical acceleration value is outside the predetermined value range and the state outside the predetermined value range continues for a predetermined time or more, the vibration of the vehicle is damped based on the detected vertical acceleration. In this case, when the acceleration in the vertical direction changes rapidly, it is possible to prevent the vibration control of the vehicle body from being performed based on the detected vertical acceleration. As a result, it is possible to prevent the ride comfort from being deteriorated.

According to the second aspect of the present invention, an actuator is provided on a vehicle wheel, and a vertical acceleration of the vehicle is detected in a suspension capable of receiving a vertical force by the actuator. ,
When the vertical acceleration value is a value within a predetermined value range, and the state within the predetermined value range continues for a predetermined time or more, the control for suppressing the vibration of the vehicle based on the detected vertical acceleration is not performed. As a result, the vibration control of the vehicle body is not performed in response to a small change in the vertical acceleration, and the effect of improving the riding comfort on a road surface with a small stroke of the suspension can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a suspension according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a main process of controlling the suspension shown in FIG. 1;

FIG. 3 is a flowchart showing a detailed process of step S1 shown in FIG. 2;

FIG. 4 is a flowchart showing a detailed process of step S1 shown in FIG. 2;

FIG. 5 is a flowchart showing a detailed process of step S1 shown in FIG. 2;

FIG. 6 is a flowchart showing a detailed process of step S2 shown in FIG. 2;

FIG. 7 is a flowchart showing a detailed process of step S2 shown in FIG. 2;

FIG. 8 is a flowchart showing a detailed process of step S3 shown in FIG. 2;

FIG. 9 is a flowchart showing a detailed process of step S4 shown in FIG. 2;

FIG. 10 is a flowchart showing a detailed process of step S3 shown in FIG. 2;

FIG. 11 is a flowchart showing a detailed process of step S4 shown in FIG. 2;

FIG. 12 is an explanatory diagram showing an example of a target value map.

FIG. 13 is an explanatory diagram showing an example of a gain map for obtaining a gain by which a target value is multiplied.

FIG. 14 is an explanatory diagram showing an example of a target value map.

FIG. 15 is an explanatory diagram showing an example of a target value map.

FIG. 16 is an explanatory diagram showing an arrangement of sensors for detecting a state of a vehicle body B.

FIG. 17 is an explanatory diagram showing an arrangement of sensors for detecting a state of a vehicle body B;

FIG. 18 is an explanatory diagram for explaining the operation shown in FIG. 7;

[Explanation of symbols]

 1L, 1R Actuator 2L, 2R Upper arm 3L, 3R Lower arm 4L, 4R Drive arm 5L, 5R Link 6L, 6R Knuckle 7L, 7R Spring GL, GR Reducer ML, MR Motor WL, WR Wheel

Continuing from the front page (72) Inventor Koichi Kitazawa 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda R & D Co., Ltd. (72) Inventor Kazuhisa Watanabe 143 Hagadai, Haga-cho, Haga-gun, Tochigi Pref. F term (reference) 3D001 AA02 AA03 AA04 BA03 CA01 DA15 EA01 EA06 EA07 EA08 EA22 EA32 EA34 EA36 EB00 EC02 EC05 EC07 EC09 ED02 ED09

Claims (2)

[Claims] 1. A suspension control method in which an actuator is provided on a wheel of a vehicle, and the actuator can apply a vertical force to the wheel by the actuator, wherein the control method detects a vertical acceleration of the vehicle. When the vertical acceleration value is out of a predetermined value range and the state outside the predetermined value range continues for a predetermined time or more, control to suppress vibration of the vehicle based on the detected vertical acceleration is performed. Characteristic suspension control method. 2. A method of controlling a suspension, wherein an actuator is provided on a wheel of a vehicle, and the wheel can receive a vertical force by the actuator, wherein the control method detects a vertical acceleration of the vehicle. When the vertical acceleration value is within a predetermined value range and the state within the predetermined value range continues for a predetermined time or more, control for suppressing vibration of the vehicle based on the detected vertical acceleration is not performed. A suspension control method characterized by the above-mentioned.