JP3092447B2 - Method for determining vehicle suspension characteristics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining vehicle suspension characteristics for optimally tuning a vehicle suspension device.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Publication No.
As disclosed in Japanese Unexamined Patent Publication No. 3 (1993) -1991, the front-rear compliance is increased by devising the arrangement and damping force of a shock absorber in a vehicle suspension system to improve steering stability and ride comfort of the vehicle. What you do is known.

[0003]

However, in the tuning of the above-mentioned conventional suspension device, if the suspension device is adjusted to change one parameter representing the suspension characteristics, other parameters change, and various parameters are changed. It is necessary to repeatedly perform a large number of tests and the like by trial and error in order to simultaneously optimize the system, and it takes a lot of time to tune the suspension device. SUMMARY OF THE INVENTION The present invention has been made to address the above problems, and an object of the present invention is to provide a method for determining a vehicle suspension characteristic that simply and appropriately determines a suspension characteristic used for optimally tuning a vehicle suspension device. is there.

[0004]

In order to achieve the above object, a main feature of the present invention is to provide a method for determining a suspension characteristic for a vehicle, comprising the steps of: inputting a first parameter representing a target vehicle performance; Calculating a target equivalent cornering power in consideration of the transient region based on the obtained first parameter, inputting a second parameter representing the provisional suspension characteristic, and calculating the transient region based on the input second parameter. The method comprises calculating a provisional equivalent cornering power in consideration of the above, and calculating a deviation between the provisional suspension characteristic and a suspension characteristic corresponding to the target vehicle performance based on the deviation between the computed equivalent cornering power. Another feature of the present invention resides in that the target equivalent cornering power is calculated in consideration of disturbance affecting the vehicle when the vehicle is running.

[0005]

According to the present invention as described above, by inputting the first parameter representing the target vehicle performance and the second parameter representing the provisional suspension characteristics, the provisional provision is made using the equivalent cornering power taking the transition region into account. A deviation between the suspension characteristics and the suspension characteristics corresponding to the target vehicle performance is calculated. Here, if the suspension characteristic of the current vehicle is used as the second parameter representing the provisional suspension characteristic, a deviation of the suspension characteristic for optimizing the suspension characteristic of the current vehicle is derived. If the apparatus is tuned by the deviation, the suspension characteristics of the current vehicle are set to the optimum ones. Also,
If the target equivalent cornering power is calculated in consideration of the disturbance affecting the vehicle at the time of traveling of the vehicle as in the other feature of the present invention, the suspension characteristics of the current vehicle may be considered at the time of the influence of the disturbance received at the time of traveling of the vehicle. Is set to the optimal one.

[0006]

As can be understood from the above description of the operation,
According to the present invention, only by inputting the first parameter representing the target vehicle performance and the second parameter representing the provisional suspension characteristic, a change in the suspension characteristic for optimally tuning the suspension device of the vehicle is derived. Therefore, the suspension device can be optimally tuned easily and in a short time as compared with the conventional method of tuning the suspension device by trial and error. According to another feature of the present invention, the suspension device can be optimally tuned simply and in a short time in consideration of the influence of a disturbance received when the vehicle is running.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments of the present invention, the respective cornering powers K1, K2 of the front and rear wheels and the equivalent cornering powers Cp1, C2 of the front and rear wheels used in the present invention will be described.
p2 and front and rear wheel complex cornering power Cp * 1 (s), Cp
* 2 (s) will be described.

FIG. 1A shows a model of the static characteristics of a suspension system and a steering system using a vehicle model. The parameters are as follows. F1, F2: Cornering forces of front and rear wheels K1, K2: Cornering power of front and rear wheels (constant determined by tire characteristics) δ: Steering angle by steering ξ1, ξ2: Compliance of front and rear suspension and steering systems (lateral force) Each steering angle u, v, V: each speed in the front, rear, lateral and forward directions of the vehicle β: vehicle slip angle r: yaw rate m: vehicle weight I ... Moment of inertia of vehicle a, b ... Distance from the center of gravity of vehicle to front and rear axles.

FIG. 1 (B) shows a case where the steering angles ξ1 and 生 じ る 2 caused by the compliance of the front and rear wheel suspension system and the steering system are eliminated for simplification, and the steering angles ξ1 and ξ2 are used.
Is represented by an equivalent vehicle model in which the effects of the above are considered in the equivalent cornering powers Cp1 and Cp2. Therefore,
The equivalent cornering powers Cp1 and Cp2 are different from the cornering powers K1 and K2 in FIG. 1A and represent the capabilities of the suspension system and the steering system of the vehicle.

FIG. 2A shows a vehicle model in which the vehicle model shown in FIG. 1A is extended to a transient region so that the generation timing of a cornering force can be considered. FIG. 2 (B)
1B is a vehicle model in which the vehicle model of FIG. 1B is extended to a transient region so that the generation timing of a cornering force can be considered. In this case, each cornering power of the front and rear wheels is converted to a complex cornering power Cp * 1 (s ), Cp * 2
(s). In these vehicle models, each parameter treated as a variable is represented using a Laplace operator s. Therefore, the complex cornering powers Cp * 1 (s) and Cp * 2 (s) in the vehicle model of FIG. 2B represent the capabilities of the vehicle's suspension system, steering system, etc., including the timing at which the cornering force is generated. . These complex cornering powers Cp * 1 (s), Cp * 2
Let (s) be represented by the following equation (1).

[0011]

## EQU1 ## Cpi (s) = K * i. (1 + Ti.s) (i = 1,2) In the above equation 1, the coefficient K * i is equivalent to the equivalent cornering power Cp1,
The coefficient Ti corresponds to the generation advance (or delay) time of each cornering force of the front and rear wheels.

In the vehicle model shown in FIG. 2 (B), the yaw natural frequency, steady slip gain, stability factor, and yaw damping ratio of the vehicle as the vehicle performance are denoted by ω, G, K, そ れ ぞ れ, respectively. Then, the following equations 2 to 9 are established by the equation of motion of the vehicle.

[0013]

(Equation 2)

[0014]

(Equation 3)

[0015]

(Equation 4)

[0016]

(Equation 5)

[0017]

[Equation 6] ω ² = Cw · ω0 ²

[0018]

数 · ω = Cf · Cw · ζ0 · ω0

[0019]

(Equation 8)

[0020]

## EQU9 ## Cf = 1 + [{(a + b) ² · K * 2−a · m · u ² } · K *
1 · T1 + {(a + b) ² · K * 1 + b · m · u ² } · K * 2 · T2] /
^{{(I + a 2 · m} ) · K * 1 + (I + b 2 · m) · K * 2} However, in the number 2 to 9, .omega.0 equivalent cornering power Cpi ignoring phases (i = 1, 2) Represents the yawing natural frequency (constant) of the vehicle calculated using the above, and Cw represents a correction coefficient (constant) for the yawing natural frequency ω0 in consideration of the phase. ζ0 represents the yawing damping ratio (constant) of the vehicle calculated using the equivalent cornering power Cpi (i = 1, 2) ignoring the phase, and Cf represents the yawing damping ratio ζ0 considering the phase. It represents a correction coefficient (constant).

On the other hand, parameters such as roll steer coefficient, roll center height, suspension lateral rigidity and lateral force compliance steer coefficient representing the front wheel suspension characteristics, and each coefficient K of complex cornering power Cp1 (s).
* 1 and the relationship with T1 are as follows. If the roll steer coefficient is q (rad / rad), the coefficient K *
The relationship between T1 and the roll steer coefficient q is given by
It looks like 1.

[0022]

(Equation 10)

[0023]

[Equation 11]

Assuming that the height of the roll center is p (m),
The relationship between the coefficients K * 1, T1 and the roll center height p is as shown in the following Expressions 12 and 13.

[0025]

[Expression 12] K * 1 = K1

[0026]

(Equation 13)

The lateral stiffness of the front wheel suspension is ks1 (N /
m), coefficients K * 1, T1 and suspension lateral rigidity ks
The relationship with 1 is as shown in the following Expressions 14 and 15.

[0028]

[Expression 14] K * 1 = K1

[0029]

(Equation 15)

The lateral force compliance steer coefficient is represented by d (r
ad / N), the relationship between the coefficients K * 1, T1 and the lateral force compliance steer coefficient d is as shown in the following equations (16) and (17).

[0031]

(Equation 16)

[0032]

T2 = 0 Further, parameters such as a roll steer coefficient, a roll center height, a suspension lateral rigidity and a lateral force compliance steer coefficient representing the rear wheel suspension characteristics, and each coefficient K of the complex cornering power Cp2 (s). * 2, the relationship with T2 is as follows. If the roll steer coefficient is q (rad / rad), the coefficient K *
2, The relationship between T2 and the roll steer coefficient q is given by
It looks like 9.

[0033]

(Equation 18)

[0034]

[Equation 19]

Assuming that the height of the roll center is p (m),
The relationship between the coefficients K * 2, T2 and the roll center height p is as shown in the following Expressions 20 and 21.

[0036]

[Equation 20] K * 2 = K2

[0037]

(Equation 21)

The lateral stiffness of the rear suspension is ks2 (N /
m), the coefficient K * 2, T2 and suspension lateral rigidity ks
The relationship with 2 is as shown in the following Expressions 22 and 23.

[0039]

## EQU22 ## K * 2 = K2

[0040]

(Equation 23)

The lateral force compliance steer coefficient is represented by d.
(Rad / N), the relationship between the coefficients K * 2, T2 and the lateral force compliance steer coefficient d is as shown in the following Expressions 24 and 25.

[0042]

(Equation 24)

[0043]

T2 = 0 Next, an apparatus and method for determining the vehicle suspension characteristics using these relationships will be specifically described.

This device is constituted by a computer. As shown in FIG. 3, the computer includes a CPU 11, a ROM 12, and a RAM 13 connected to the bus 10. The CPU 11 executes the program shown in the flowchart of FIG. 4, and the ROM 12 stores the program and a map used during the execution of the program. This map is based on Equation 1 described above.
The complex cornering powers Cp * 1 (s), Cp * are defined by using the roll steer coefficient q, roll center height p, suspension lateral stiffness ks1, ks2, and lateral force compliance steer coefficient d represented by 0 to 25 as one axis. It is composed of a function table in which each of the coefficients K * 1, T1, K * 2, and T2 of 2 (s) is the other axis, so that one can be derived as a factor and the other as a function value. . RA
M13 temporarily stores variables during execution of the program.

The bus 10 includes a keyboard 14 and a display device 1.
5 and a printer 16 are also connected. Keyboard 14
The input means comprises a plurality of switches, and can input various parameter values.
Note that, in addition to the keyboard 14, an external storage device such as a flexible disk can be used as the input means. The display device 15 is provided with a screen to visually notify an operator of an input procedure, a calculation result, and the like. The printer 16 prints and outputs calculation results and the like.

Next, a method for determining the vehicle suspension characteristics using the computer will be described. C
The PU 11 starts the execution of the program in step 20 of FIG.
Basic vehicle specifications such as (vehicle speed at which target vehicle performance is to be exhibited), moment of inertia I of the vehicle for which suspension characteristics are to be determined, weight m, and distances a and b from the center of gravity of the vehicle to each axle of the front and rear wheels are keyboard-coded. The user inputs an instruction on the display device 15 to perform the operation. When the operator designates the standard vehicle speed u and the basic vehicle specifications I, m, a, and b using the keyboard 14, the CPU 11 specifies the standard vehicle speed u and the basic vehicle specifications I, m, a, and b. Input and store in RAM 13. Next, the CPU 11 inputs the yaw natural frequency ω, the steady slip gain G, the stability factor K, and the yaw damping ratio と し て of the vehicle to the operator with the keyboard 14 as parameters representing the target vehicle performance in step 22. Is displayed on the display device 15. When the operator specifies these parameters ω, G, K, を using the keyboard 14, the CPU 11 inputs the specified parameters ω, G, K, ζ and stores them in the RAM 13.

After the processing in steps 21 and 22, the CPU
Numeral 11 denotes the standard vehicle speed u, basic vehicle specifications I, m, a, b and parameters ω, G, K, ζ representing the target vehicle performance, which have been inputted and stored in the RAM 13 in step 23, as described in the above equations (2) to (9). And the target complex cornering power Cp * 1 (s), Cp * 2 (s), that is, the coefficients K * 1, K * 2, T1,
T2 is calculated and stored in the RAM 13. Equations (2) to (9) represent parameters ω, G, K, ζ representing the target vehicle performance and a coefficient K.
* 1, K * 2, T1, T2, that is, eight equations with eight variables, the parameters ω,
Obviously, the coefficients K * 1, K * 2, T1, and T2 are calculated by giving G, K, and. Note that ω0, Cw, ζ0, and Cf in the above Expressions 2 to 9 are fixed values and are stored in advance in the program as described above. Further, these values ω0, Cw, ζ0, Cf may be input by the processing of step 21 or step 22.

Next, at step 24, the CPU 11 provides the operator with parameters representing the provisional suspension characteristics of the vehicle, such as the roll steer coefficient q, the roll center height p, the suspension lateral stiffness ks1, ks2 of the front and rear wheel suspensions, and An instruction is given on the display device 15 to drive the lateral force compliance steer coefficient d with the keyboard 14. The provisional suspension characteristics are basic suspension characteristics, for example, current suspension characteristics of a vehicle to be tuned in the future. When the operator specifies these parameters q, p, ks1, ks2, and d by using the keyboard 14, the CPU 11 inputs the specified parameters q, p, ks1, ks2, and d to set the RA.
It is stored in M13.

After the processing in step 24, the CPU 11 determines in step 25 that the ROM 1
Using the maps prepared in FIG. 2, the coefficients K * 10 and T10 of the complex cornering power Cp * 10 (s) respectively corresponding to the parameters q, p, ks1, and d representing the provisional suspension characteristics for the front wheels are calculated. The calculated values are stored in the RAM 13 and the coefficients K * 20 and T20 of the complex cornering power Cp * 20 (s) respectively corresponding to the parameters q, p, ks2 and d representing the provisional suspension characteristics for the rear wheels are calculated. Stored in the RAM 13. Thereby, each coefficient K for the front wheel is obtained.
* 10, T10 and each coefficient K * 20, T20 for rear wheel are 4
Each set is stored in the RAM 13.

Next, as shown in the following equations (26) and (27) in step 26, the CPU 11 calculates each complex cornering power Cp * to be the target for the front and rear wheels calculated based on the target vehicle performance by the processing in step 23. 1 (s), Cp * 2 (s)
From the coefficients K * 1, K * 2, T1, and T2 of step 25,
4 sets of complex cornering power Cp * 10 for front and rear wheels calculated based on provisional suspension characteristics
By subtracting the respective coefficients K * 10, T10, K * 20 and T20 of (s) and Cp * 20 (s), the deviations ΔK * 1, ΔT1, ΔK * are obtained.
2. Calculate ΔT2 and store it in the RAM 13. Thereby, the deviations ΔK * 1 and ΔT1 of the coefficients K * 10 and T10 for the front wheels and the deviations ΔK * 2 and ΔT2 of the coefficients K * 20 and T20 for the rear wheels are stored in the RAM 13 by four sets. Will be.

[0051]

(26) ΔK * i = K * i−K * i0 (i = 1, 2)

[0052]

.DELTA.Ti = Ti-Ti0 (i = 1, 2) After the processing of step 26, the CPU 11 proceeds to step 27.
Display that the operator inputs two noticeable suspension characteristics out of the roll steer coefficient, the roll center height, the suspension lateral rigidity, and the lateral force compliance steer coefficient with the keyboard 14 for each of the front and rear wheels. 15 on top. When the operator specifies two suspension characteristics using the keyboard 14,
The CPU 11 inputs the suspension characteristics of the two designated front and rear wheels, and advances the program to step 28.

In step 28, the CPU 11
The deviations ΔK * 1, ΔT stored in the RAM 13 corresponding to the respective suspension characteristics by the processing of the step 26
Front wheel deviations ΔK * 1, ΔT1 corresponding to the two specified suspension characteristics from among 1, ΔK * 2, ΔT2
And two deviations ΔK * 2 and ΔT2 for the rear wheels
ROM 12 corresponding to the specified suspension characteristics
The extracted deviations ΔK * 1, Δ based on the respective maps in
The deviation of the suspension characteristics corresponding to T1, ΔK * 2 and ΔT2 is calculated. That is, regarding the specified suspension characteristics, the complex cornering power Cp * corresponding to the provisional suspension characteristics with reference to the respective maps for the front and rear wheels.
Coefficients K * 10, T10, K * 20, T20 of 10 (s) and Cp * 20 (s)
Is the deviation ΔK * 1 calculated by the processing in step 26.
A target suspension characteristic value in the case of changing by 0, ΔT10, ΔK * 20, and ΔT20 is obtained, and a difference between the target suspension characteristic value and the provisional suspension characteristic value is calculated as a change amount of the suspension characteristic. Each is stored in the RAM 13.

The two suspension characteristics for each of the front and rear wheels are designated in this manner because the coefficients K * 1, T of the complex cornering powers Cp * 1 (s) and Cp * 2 (s) for the front and rear wheels are specified.
This is because, even if 1, K * 2 and T2 are respectively changed, only at most two of the suspension characteristics for the front and rear wheels can be changed. Accordingly, in step 27, the operator determines the coefficients K * 1, T1, K * 2, and Kp * 1 (s) of the complex cornering power Cp * 2 (s).
It is appropriate to select two types of suspension characteristics in which the two types of suspension characteristic values of the front and rear wheels can be independently changed by designating T2. That is, Equations 10 to 25
As is apparent from the above, it is advantageous for the operator to select, for example, a combination of the roll center height q and the lateral force compliance steer coefficient d, a combination of the suspension lateral stiffness ks1, ks2 and the lateral force compliance steer coefficient d. Then, in step 28, the CPU 11 sets the coefficient K *
The deviation ΔK of the coefficients K * 1, T1, K * 2, T2 on the side where the suspension characteristics change depending on the changes of 1, T1, K * 2, T2.
It goes without saying that * 10, ΔT10, ΔK * 20, ΔT20 are used. For example, when a combination of the roll center height q and the lateral force compliance steer coefficient d is specified, the change amount Δq of the roll center height q is calculated from the deviations ΔT10 and ΔT20, and the deviations ΔK * 10 and ΔK * According to 20, the lateral force compliance steer coefficient d is calculated.

After the processing in step 28, the CP
U11 displays the data representing the change amount of the suspension characteristics for the front and rear wheels calculated in step 29 on the display device 15.
And output to the printer 16 respectively. The display device 15 displays the change amount of the suspension characteristics on a screen, and the printer 16 prints the change amount of the suspension characteristics. The change amount of the suspension characteristics displayed on the screen and printed is used for tuning of the suspension device of the vehicle, and the characteristics of the suspension device are corrected by the change amount.

As described above, according to the above embodiment, the yaw natural frequency ω, the steady slip gain G, the stability factor K, and the yawing damping ratio ζ of the vehicle are input as the parameters representing the target vehicle performance (step). 2
2), the respective coefficients K * 1, T1, K * 2, of the complex cornering power Cp * 1 (s) and Cp * 2 (s) corresponding to the target vehicle performance.
T2 is calculated (step 23). Further, as parameters representing the provisional suspension characteristics (suspension characteristics of the current vehicle), the roll steer coefficient q, the roll center height p, the lateral stiffness ks1, ks2 of the front and rear wheel suspensions, and the lateral force compliance steer coefficient d are input ( Step 24), complex cornering powers Cp * 10 (s) and Cp * 20 corresponding to the provisional suspension characteristics
The coefficients K * 10, T10, K * 20, and T20 of (s) are calculated (step 25). Then, these coefficients K * 1, T1, K *
Change from the provisional suspension characteristics to the suspension characteristics corresponding to the target vehicle performance by using 2, T2, K * 10, T10, K * 20, T20 and the parameters q, p, ks1, ks2, d representing the provisional suspension characteristics. The amount was calculated (steps 26-28) and the calculated change amount was displayed and printed (step 29) so that it could be used as a change amount for tuning the suspension system of the current vehicle. In this case, the complex cornering powers Cp * 1 (s) and Cp * 2 (s) used to mediate the calculation of the change amount of the suspension characteristics.
Can better tune the suspension device easily and in a short time because it represents the suspension characteristics of the vehicle better.

The equations (2) to (9) used in the calculation in step 23 in the above embodiment are satisfied when the vehicle is traveling at a normal speed. Receive. Therefore, in this case,
It is necessary to use complex cornering powers Cp * 1 '(s) and Cp * 2' (s) in consideration of the aerodynamic moment coefficient Cy and the aerodynamic lateral force coefficient Cz. The coefficients K * 1 'and K * 2' representing the equivalent cornering powers of the complex cornering powers Cp * 1 '(s) and Cp * 2' (s) and the corresponding coefficients K * of the above embodiment.
1, K * 2 and the following equations 28 and 29,
A coefficient T2 'representing the phase advance (delay) time of the complex cornering power Cp * 2' (s) is expressed as in Equation 30.

[0058]

[Equation 28]

[0059]

(Equation 29)

[0060]

[Equation 30]

Therefore, in the above embodiment, if the vehicle is running at such a high speed as to be affected by aerodynamics as a disturbance, the aerodynamic moment coefficient Cy and the aerodynamic lateral force coefficient Cz are set as the vehicle parameters in step 21. To enter. Then, in the calculation process in step 23,
The coefficients K * 1 'and K * 2' are calculated based on Equation 9 and Equations 28 and 29, and the coefficient T2 'is calculated based on Equation 30. In Step 26, the coefficients K * 1, K * 2 and T2 are calculated. Instead, the coefficient K * 1 ',
K * 2 'and T2' are used. According to this, ideal vehicle performance can be obtained even at the time of high-speed running that is affected by aerodynamics.

In the above embodiment, step 2
Although the vehicle specifications and various parameters are input in accordance with the operation of the keyboard 14 at 1, 22, and 24, they may be input from an external recording medium such as a flexible disk or another storage disk prepared in advance. Good.

[Brief description of the drawings]

FIG. 1A is a vehicle model diagram showing static characteristics of a suspension system and a steering system, and FIG. 1B is an equivalent vehicle model diagram obtained by simplifying the vehicle model of FIG.

FIG. 2A is a vehicle model diagram in which the vehicle model is extended to a transient region, and FIG. 2B is an equivalent vehicle model diagram in which the vehicle model is simplified.

FIG. 3 is a block diagram of a computer used in an embodiment of the present invention.

FIG. 4 is a flowchart of a program executed by the computer of FIG. 3;

[Explanation of symbols]

11 CPU, 12 ROM, 13 RAM, 14 keyboard, 15 display device, 16 printer.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-37015 (JP, A) JP-A-7-69021 (JP, A) JP-A-6-297983 (JP, A) JP-A-6-297983 156037 (JP, A) JP-A-6-122311 (JP, A) JP-A-6-122310 (JP, A) JP-A-63-137007 (JP, A) JP-A-2-155816 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60G 17/015

Claims (2)

(57) [Claims] 1. A step of inputting a first parameter representing a target vehicle performance; a step of calculating a target equivalent cornering power in consideration of a transient region based on the input first parameter; Inputting two parameters; calculating a provisional equivalent cornering power in consideration of a transient region based on the input second parameter; provisional suspension characteristics and target vehicle performance based on a deviation between the calculated equivalent cornering powers. Calculating a deviation from a suspension characteristic corresponding to the vehicle suspension characteristic. 2. The suspension characteristic of a vehicle according to claim 1, wherein in the step of calculating the target equivalent cornering power, the target equivalent cornering power is calculated in consideration of a disturbance affecting the vehicle during running of the vehicle. Decision method.