JPH03186413A - Method and device for controlling rolling of vehicle - Google Patents

Abstract

PURPOSE:To contrive high responsiveness of a roll and prevention of its hunting by decreasing a damping rate of a shock absorber in the initial period of rolling generation and increasing the damping rate in the latter period of generation while executing a control being based on the lateral acceleration-roll angle transmission characteristic. CONSTITUTION:In the case of controlling rolling of a car body C, with a wheel B suspended, by a suspension device A provided with a shock absorber in which a damping rate can be changed, the damping rate is decreased in the initial generation period of rolling and increased in the latter period of generation. That is, lateral acceleration information of the car body C is presented by a means D, and roll rate information is presented by a means E being based on this lateral acceleration information. Target rolling moment is calculated in a means F being based on the lateral acceleration information further with a target roll damping rate determined by a means G being based on the roll rate information and the target rolling moment. Further, the damping rate of the shock absorber is controlled by a means H based on the target roll damping rate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a device for controlling rolling of a vehicle during manual lateral acceleration, particularly transient roll response.

(Prior Art) Since the wheels of a vehicle are suspended by a vibration damping suspension device equipped with a shock absorber, rolling of the vehicle body occurs when lateral acceleration is input.

To explain the roll response of a vehicle whose wheels are suspended by the suspension device, it is known that the equation of motion of rolling motion with respect to lateral acceleration and human force is approximately expressed by the following equation.

However, α...Lateral acceleration φ...Roll angle ■,...Roll inertia C...Roll damping rate φ (roll damping rate due to all-wheel shock absorber) K...Roll due to all-wheel suspension device φ Rigidity H9...Center of gravity height H...Roll center height L...Spring mass By the way, the above roll damping rate C is the damping rate related to the stroke of the front and rear wheels.
AF +C3AII, front and rear treads are each Tr,
Let T* be expressed as follows. On the other hand, when the transfer characteristic of the roll angle φ to the lateral acceleration α is expressed using the differential operator S based on the equation (1), it becomes as shown in the following equation.

However, as is clear from equations φ (2) and (3), the damping rate C3AF +C5Al of the shock absorber only affects the damping characteristic C9ξ with respect to rolling motion, but the shock absorber also affects the damping characteristic C9ξ when driving on rough terrain. It also plays another role: suppressing the vertical and pitching motion of the vehicle body that occurs during braking and driving, and providing a comfortable ride.

Therefore, in general passenger cars, the damping rate C5AF + C3AR of the shock absorber is determined so that the former damping effect against rolling motion and the latter damping effect for ensuring ride comfort can be combined in a well-balanced manner. In this case, the damping coefficient ξ of the rolling motion takes a value around 0.3.

By the way, in a vehicle where ξ=0.3 as described above, the case where a step-like steering angle as shown in FIG. 9(a) is given and the lateral acceleration shown in FIG. 9(b) is generated will be described as follows.
The rolling attenuation rate C=33.0kgf-m・S by the shock absorber corresponding to ξ-0,3, which is not shown in (d) of the same figure, causes rolling as shown in (a) in (C) of the same figure. do. As is clear from this transient characteristic (a), the roll angle that occurs once overshoots, then undershoots (hunting) repeatedly, and then settles down to the roll angle that corresponds to the final steering angle. , the above damping rate of the shock absorber does not provide good damping characteristics for rolling motion.

To solve this problem, conventionally, Japanese Patent Application Laid-Open No. 58-30815
JP-A-58-30818, JP-A-58-
As described in Japanese Patent Application Laid-open No. 116214 and Japanese Patent Application Laid-open No. 167210/1983, techniques have been proposed in which the turning state is detected by various methods and the damping rate of the shock absorber is increased when rolling occurs.

(Problem to be Solved by the Invention) In this case, in order to solve the above problem, it is said that it is best to determine the damping rate of the shock absorber so that the damping coefficient ξ of the rolling motion is approximately 0.7. There is. Therefore, when ξ= as shown in Fig. 9(d), the roll response becomes as shown in Fig. 9(C) (b), and the damping characteristic of the rolling motion is improved by Salermo's roll angle. The delay in onset becomes noticeable.

In this case, especially during driving in which reverse steering is repeated, such as in slalom driving, the roll phase delay is large, leading to a worsening of the steering feeling.

The present invention is characterized in that each of the above-mentioned problems is solved by controlling the suspension device one by one so that the occurrence of the roll angle with respect to the lateral acceleration is always as intended.

(Means for solving the problem) For this purpose, the rolling control method of the present invention is shown in FIG.
As shown in the concept in a), when controlling the rolling of a vehicle with wheels suspended by a suspension device equipped with a shock absorber that can change the damping rate, the roll damping rate by the all-wheel shock absorbers becomes small at the beginning of rolling. Rolling is achieved through a sequential combination of an initial damping rate decreasing step that determines the damping rate of the shock absorber and a late damping rate increasing step that determines the damping rate of the shock absorber such that the roll damping rate increases after the initial stage of rolling. Control.

Further, as the concept of the rolling control device of the present invention is shown in FIG. 1 (1)), in a vehicle whose wheels are suspended by a suspension device equipped with a shock absorber that can change the damping rate, information on lateral acceleration acting on the vehicle body is provided. lateral acceleration information providing means for providing information on the roll rate of the vehicle body from this lateral acceleration information; and roll rate information providing means for providing information regarding the roll rate of the vehicle body from this lateral acceleration information;
a target rolling moment calculation means for calculating a target rolling moment for achieving the roll angle position characteristic; and a target roll damping rate for achieving the lateral acceleration-roll angle transfer characteristic from the roll rate information and the target rolling moment. Means for determining the roll damping rate to be obtained;
A shock absorber damping rate control means is provided for controlling the damping rate of the shock absorber so that the target roll damping rate is achieved.

(Function) In the method of the present invention, when the vehicle body rolls due to lateral acceleration, the roll damping rate by all wheel shock absorbers is reduced in the initial damping rate reducing step at the initial stage, and then the roll damping rate is reduced in the late damping rate increasing step. Increase the attenuation rate. Therefore, at the beginning of rolling, the roll damping rate is small, which increases the roll response and reduces the roll onset delay (
Afterwards, due to the large roll damping rate, roll hunting is suppressed, and the roll can quickly settle to the roll angle corresponding to the final steering angle, resulting in a high roll. It is possible to achieve both response and reliable prevention of roll hunting.

Next, according to the device of the present invention, the target rolling moment calculating means calculates the target rolling moment to achieve the desired lateral acceleration -11] - angle transfer characteristic based on the lateral acceleration information from the lateral acceleration information providing means. Calculate. On the other hand, the roll damping rate determining means determines a target roll damping rate for achieving the desired lateral acceleration-roll angle transfer characteristic from the roll rate information from the roll rate information providing means and the target rolling moment, and The absorber damping rate control means controls the damping rate of the shock absorber so that the target roll damping rate is achieved. Therefore, the roll damping rate is controlled one by one through damping rate control of the shock absorber so that the targeted lateral acceleration-roll angle transmission characteristic is always achieved, and as a result, this roll damping rate is small at the beginning of rolling occurrence. By increasing the size in the later stages, it is possible to achieve both high roll compatibility and reliable roll hunting prevention.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows an embodiment of the rolling control device of the present invention, in which 1 is a sensor for detecting the steering angle θ, 2 is a sensor for detecting the vehicle speed V, and 3 is a microcomputer. The microcomputer 3 controls the damping force of the left and right front wheel shock absorbers 5L, 5R and the left and right rear wheel shock absorbers 6L, 6R of the suspension system via the shock absorber control section 4 based on the input information from both sensors 1.2. It is assumed that rolling control, which is the object of the invention, is performed.

The microcomputer 3 is actually the third microcomputer for this control.
The control programs shown in FIGS. and 4 are executed, but for convenience, they are shown in functional blocks: a yawing and lateral motion estimation section 7, a rolling motion target value calculation section 8, a target rolling moment calculation section 9, and a shock absorber roll. It is composed of an attenuation rate determination section 10.

Figure 3 shows the main routine that starts when the power is turned on.
Step 31, which is executed only once when the power is turned on, initializes the yaw rate ψ, yaw angular acceleration ψ, lateral velocity vy, lateral translational acceleration vy, target roll rate φ, and target roll to be used in later calculations. rate φ
, and target roll angular acceleration φ, are reset to O, respectively. Then, in the next step 32, the subroutine shown in FIG. 4 is executed by interrupting Δ every time.

In this subroutine, first, in step 41, the vehicle speed V and steering angle θ are read, and the next step 42 corresponds to the yawing and lateral motion estimating section 7 in FIG.
By solving the equation of motion regarding yawing and lateral motion from the steering angle θ and the steering angle θ, the lateral acceleration is estimated as follows, and the estimated lateral acceleration α is obtained.

C, -eKy (θ/N - (V, +LF 51')
/V)R=KR(Vy+Rψ)/V-(2L.

F 2t,w c,)/I.

-(2CF + 2C*)/M However, eK,...Front wheel equivalent cornering power 8...Rear wheel cornering power CF...Front wheel cornering force C11...Rear wheel cornering force L,...Front wheel - Distance between the center of gravity, ... Rear wheel - Distance between the center of gravity This equation of motion is a well-known one based on a linear two-degree-of-freedom two-wheel model, but the integration method for determining ψ and vy takes the longest calculation time. Saving Euler method p=p+Δt'
It is advantageous to use p, V, = Vy-1-ΔtVy.

Step 43 in FIG. 4 corresponds to the rolling motion target value calculation unit 8 in FIG. The corresponding rolling motion target values, that is, the target roll angle φ1, target roll rate φ1, and target roll angular acceleration φ for achieving the targeted lateral acceleration-roll angle transfer characteristic are calculated as follows.

φ -6f φ ・dt The reference model is given as a physical rolling motion model, with roll inertia at a predetermined value IXR, roll damping rate plus mass M1, center of gravity height II9, and roll center height H.

Regarding this, vehicle specification values are used to adjust the steady roll angle gain of the vehicle to be controlled. Therefore 1. ,
, C can arbitrarily determine the desired lateral acceleration φ dead roll angle transfer characteristic, and in the present invention, this characteristic can be determined as shown in FIG.
C) As shown in (c), there is no delay in the occurrence of roll angle as in characteristic (I), and there is no hunting as in characteristic (A). Note that φ1. The integration method for finding φ0 is also φ, -φ, +Δtφ1. It is advantageous to use the Euler method of φ, -φ, →Δtφ.

Step 44 in FIG. 4 corresponds to the target rolling moment calculation section 9 in FIG. 2, and here the rolling motion target value φ is calculated. , φ1. φ1, that is, the target lateral acceleration-roll angle transfer characteristic, roll inertia is ■8, and roll rigidity is K.
, the sprung mass is M3, the height of the center of gravity is +49, and the l:l-le center height is 11. The target rolling moment u required to achieve this with an actual vehicle is calculated. By the way, if the rolling moment generated by the shock absorber is U, then the above equation (1) can be rewritten as follows. In the following equation, replacing ``φ°, φ with the rolling motion target value ``φ°, φ1, and replacing α with the estimated lateral acceleration α, the above target rolling moment U can be obtained by calculating the following.

In step 45 in Fig. 4, target roll rate 1 - absolute value
Check whether φ1 is greater than or less than the minute setting value. This check determines the ideal roll damping value. If φ is 0 or extremely small, C becomes infinite or an extremely large value, making it impossible to calculate on an actual computer or causing an overflow. If it is determined in step 45 that φ is extremely small, in step 46 the target roll damping rate C is set to a large predetermined value within a range of φ that does not cause any inconvenience. Note that C may be determined by running a ride comfort control program instead of φ. When it is determined in step 45 that φ does not cause the above problem, the step 47 corresponds to the calculation block 10a forming a part of the sober roll attenuation rate determination unit 10. However, C may take a negative value or exceed the damping rate control range of the actual shock absorber.
The remainder of the next step 48 corresponds to the limiter 10b.
Then, C is unconditionally set as the target roll damping rate φ.In step 49, the target roll damping rate C determined in step 46 or 48 is outputted to the shock absorber φ-c controller 4 shown in FIG. This control section controls the shock absorber 5L so that the target roll damping rate C can be obtained.

φ Controls the attenuation rate of 5R, 6L, and 6R. Therefore, the target rolling moment tu calculated in step 44 is obtained, and the roll angle targeted by the lateral acceleration-roll angle transfer characteristic given as described above can be generated. For example, referring to the steering operation mode shown in Fig. 9,
In light of the above transfer characteristics, the roll damping factor C is shown in Figure 9 (d
) and (d), the rolling angle is small at the beginning of the rolling, and then gradually changed to become sharper, and the roll angle can be generated as shown in (c) in FIG. 9(c). (c) Characteristics, (b) and (
0) As is clear from the comparison with the characteristics, in this example, it is possible to achieve both quick attenuation (convergence) of the roll response to lateral acceleration and quick roll generation.

Note that in the above example, the lateral acceleration was estimated by the steering angle sensor 1, vehicle speed sensor 2, and yaw and lateral movement estimation unit 7 and the estimated lateral acceleration α was used. The detected lateral acceleration may be used.

FIG. 5 shows another example of the present invention, in which the target rolling moment calculation section 9 and the rolling movement target value calculation section 8 of FIG. - The target roll rate transfer function block 52 is replaced with each other.

Block 51 uses a transfer function W (s) that specifies the relationship between the estimated lateral acceleration α and the target Rorig moment U.
Target rolling moment U corresponding to estimated lateral acceleration α
This is a block that searches for . In order to obtain the transfer function W(s), if the differential equation of the reference model is rewritten using the differential operator S, the following equation is obtained.

ΔG.

(s) α...(5) However, φ Further, the roll response of the vehicle with lateral acceleration α and rolling moment U as input is expressed by the following equation.

however The purpose of this control is to set the roll angle φ to the target roll angle φ.

(to make φ=φ), α−7
Considering this, the estimated lateral acceleration (α)−target rolling moment (u) transfer characteristic−(s) becomes as shown in the following equation.

Block 52 is a block for calculating the estimated lateral acceleration α, the target roll rate, and the target roll rate φ corresponding to the estimated lateral acceleration α. It can be seen that the transfer characteristic is expressed by equation (5). Block 51.52 (7)
.

Transfer characteristics W(s), SG, (s
) is actually configured as a digital filter, but excluding calculation errors due to differences in calculation methods, the target rolling moment U and target roll rate φ with respect to α are the second
This is the same as shown in the figure, and this example can also provide the same effects as the example described above.

6 and 7 show still another example of the present invention according to FIGS. 2 and 4, and in this example, a rolling motion estimation section 61 is added as shown in FIG. As shown in FIG. 7, step 71 is added before step 49. As a result, in this example, the estimated roll rate φ is used instead of the target roll rate φ. In other words,
In the rolling motion estimating section 61 and step 71, the rolling motion is estimated by solving the equation of motion to obtain the estimated roll rate . (See step 47 in FIG. 7) is temporarily stored in memory. Therefore, the calculation of C in block 10a and step 47 depends on the previous estimated roll rate φ and T. Therefore, step 45 is changed to check whether ■ is greater than or equal to the minute setting value L2, step 43 The rolling motion target value found by is the target roll angle φ
. and target roll angular acceleration φ.

Note that when calculating the ideal roll damping rate C in block 10a (step 47), the target roll rate φ7 is used in the φ examples of FIGS. 2 to 5, and the target roll rate φ7 is used in the examples of FIGS. 6 and 7. Although the estimated roll angle T is used here, it goes without saying that it is also possible to actually measure the roll rate φ using a rate gyro or the like and use this in the calculation.

FIG. 8 shows still another example of the present invention, in which the estimated lateral acceleration α is obtained from a rear wheel steering controller 81. This rear wheel steering controller is based on the well-known article described in "New Control Method for Four-Wheel Steering Vehicles" published in August 1988, "Proceedings of the Society of Instrument and Control Engineers," vol. 1.23° No. 8, pages 48 to 54. Sensor 1. A rear wheel steering angle δ8 is commanded to the rear wheel steering system 82 to obtain a lateral acceleration α corresponding to the steering angle θ and the vehicle speed V detected in step 2. Therefore, by manually inputting the lateral acceleration α to the microcomputer 3 as the estimated lateral acceleration, it is possible to achieve the same effects as in the example described above.

In this example, in addition to eliminating the need for the microcomputer 3 to estimate lateral acceleration, there is an advantage that the rolling control computer 3 and the rear wheel steering controller 81 can be integrated into a common computer.

Note that since the lateral acceleration estimation α follows the lateral acceleration target value y, y may be used instead of i.

(Effects of the Invention) Thus, according to the rolling control method of the present invention, the roll damping rate is reduced at the initial stage of rolling occurrence, and then the roll damping ratio is increased, so that the roll response is increased in the former and the roll onset delay is reduced. Moreover, in the latter case, hunting of the roll is suppressed and the roll can be quickly settled to the final roll angle, making it possible to achieve both high roll response and prevention of hunting of the roll.

Further, according to the rolling control device of the present invention, the roll damping rate is controlled one by one through damping rate control of the shock absorber based on the targeted lateral acceleration-roll angle transfer characteristic, which can be set to achieve both of these properties. As a result, the roll damping rate is small in the early stages of rolling occurrence and becomes large in the latter stages, making it possible to achieve both high roll response and reliable prevention of roll hunting.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are conceptual diagrams of the rolling control method and rolling control device of the present invention, respectively. FIG. 2 is a functional block diagram showing an embodiment of the device of the present invention. FIGS. 3 and 4 is a flowchart 1 showing the control program of the microcomputer in the same example, FIG. 5 is a functional block diagram showing another example of the device of the present invention, and FIG. 6 is a functional block diagram showing still another example of the device of the present invention. 7 is a flowchart corresponding to FIG. 4 showing the control program for the microcombination unit 1 in the same example. FIG. 8 is a functional block diagram showing still another example of the device of the present invention. FIG. 9 is a simulation diagram showing a comparison between the operation time chart of the device of the present invention and that of the conventional device. 1... Steering angle sensor 2... Vehicle speed sensor 3... Microcomputer 4... Shock absorber control unit 5L, 5R, 61,, 6R... Shock absorber 7... Yawing, lateral movement estimation unit 8... Rolling movement target value calculation unit 9... Target rolling moment calculation unit 10... Shock absorber roll attenuation rate determination unit 51... Lateral acceleration - Target rolling moment transfer function block 52... Lateral acceleration - Target roll rake 61... Rolling motion estimator 81... Rear wheel steering controller 82... Rear wheel steering system transfer function block']Q. ○ () ζr 〜

Claims (1)

[Claims] 1. When controlling the rolling of a vehicle with wheels suspended by a suspension device equipped with a shock absorber that can change the damping rate, the roll damping rate by the all-wheel shock absorbers becomes small at the beginning of rolling. and a later damping rate increasing step to determine the damping rate of the shock absorber so that the roll damping rate increases after the initial stage of rolling. A vehicle rolling control method characterized by: 2. A lateral acceleration information providing means for providing information on the lateral acceleration acting on the vehicle body in a vehicle in which wheels are suspended by a suspension device equipped with a shock absorber that can change the damping rate, and a roll rate of the vehicle body from this lateral acceleration information. roll rate information providing means for providing information related to the roll rate information; and target rolling moment calculating means for calculating a target rolling moment for achieving a targeted lateral acceleration-roll angle position characteristic based on the lateral acceleration information; roll damping rate determining means for determining a target roll damping rate for achieving the lateral acceleration-roll angle transfer characteristic from roll rate information and a target rolling moment; and controlling the damping rate of the shock absorber to achieve the target roll damping rate. 1. A rolling control device for a vehicle, comprising: shock absorber damping rate control means. 3. A vehicle according to claim 2, in which the order difference between the numerator order and the denominator order of the targeted lateral acceleration-roll angle transfer characteristic is greater than or equal to the order difference between the numerator order and the denominator order of the lateral acceleration-roll angle transfer characteristic of the actual vehicle. rolling control device. 4. In claim 2 or 3, the roll rate information providing means is configured to use, as the roll rate information, a target roll rate corresponding to the lateral acceleration information, which is determined based on the targeted lateral acceleration-roll angle transfer characteristic. Vehicle rolling control device. 5. A rolling control device for a vehicle according to claim 2 or 3, wherein the roll rate information providing means comprises roll rate estimating means that uses roll rate estimated from lateral acceleration information as roll rate information. 6. In claim 2 or 3, the target rolling moment calculation means calculates the target rolling moment from the roll angle and roll angular acceleration obtained from the targeted lateral acceleration-roll angle transfer characteristic, in addition to the lateral acceleration information. Configured vehicle rolling control device. 7. In claim 2 or 3, the target rolling moment calculation means calculates the target rolling moment corresponding to the lateral acceleration information based on the lateral acceleration-target rolling moment transfer function obtained from the target lateral acceleration-roll angle transfer characteristic. A rolling control device for a vehicle configured as follows.