JP2002079954A - Alignment adjusting method of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute alignment adjustment for fixing driving performance of a vehicle without being influenced by dispersion of tire performance. SOLUTION: A control device 80 determines a spot where the difference of lateral force fluctuation between two front wheels measured by a tire driving device 18 and the difference of lateral force fluctuation between two rear wheels become minimum, and calculates front and rear toe angles at that time. The control device 80 controls an unillustrated turning device so that the front and rear toe angles become the values at that time, to thereby execute the alignment adjustment. Then, a stability factor is calculated by using the front and rear toe angles, and the factor is compared with a reference value. The control device 80 determines that straight line traveling is stable, when the stability factor is equal to the reference value or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the alignment of a vehicle, and more particularly, to a method for adjusting the alignment of a vehicle which improves the stability of the vehicle when traveling straight.

[0002]

2. Description of the Related Art In general, alignment adjustment is performed to ensure the running stability of a vehicle. For example, a camber angle is given to a wheel, and a toe angle is given in order to prevent one-sided abrasion caused by giving the camber angle. Conversely, balance the forces generated on the front and rear tires of the vehicle,
A toe angle is provided to ensure the running stability of the vehicle, and a camber angle is provided to prevent abrasion due to the provided toe angle. Adjustments are also made by combining the toe angle and the camber angle to minimize the running stability of the vehicle and the partial wear of the tires under the constraints of the structural dimensions of the vehicle. As described above, it is important to adjust the alignment such as the toe angle and the camber angle, which are the attitude angles given to the wheels, in order to improve the stability during running of the vehicle.

In such a conventional alignment adjustment, it is common to measure an angle and a dimension for each wheel, and to adjust the measured angle and the dimension so as to coincide with a target value set at the time of designing the vehicle. there were.

[0004] However, the running state of the vehicle is affected not only by the specifications of the vehicle body but also by the performance of individual tires and the like. There is a problem that a certain running performance cannot always be maintained.

The present invention has been proposed to solve the above-mentioned problems, and can perform alignment adjustment for improving the running performance of a vehicle without being affected by variations in tire performance. An object of the present invention is to provide a method for adjusting the alignment of a vehicle.

[0006]

According to the first aspect of the present invention,
The characteristic of the lateral force fluctuation with respect to the toe angle of each wheel of the vehicle is measured, and based on the characteristic of the lateral force fluctuation with respect to the toe angle of each wheel, the difference between the lateral force fluctuation of the front left and right wheels is minimized. The common toe angle and the common toe angle of the rear left and right wheels at which the difference between the lateral force fluctuations of the rear right and left wheels is minimized, and the alignment is adjusted based on the calculated common toe angle of each wheel, and the calculated value is calculated. Based on the common toe angle of each wheel and the vehicle motion model when the alignment is adjusted, calculate a stability factor indicating the stability of straight running of the vehicle, and when the stability factor is less than a reference value, Calculate the common toe angle of the front left and right wheels and the rear left and right wheels so that the stability factor is equal to or more than the reference value and the difference between the lateral force fluctuations of the front left and right wheels and the difference between the lateral force fluctuations of the rear left and right wheels are substantially minimized. Provide adjustment process It is.

[0007] The characteristics of the lateral force variation with respect to the toe angle are different for each wheel of the vehicle, and the performance of the actual wheels, ie, the tires also varies. Therefore, even if the alignment is adjusted so as to match the target value set at the time of designing the vehicle, the straight running of the vehicle may not be stable. Therefore,
The characteristic of the lateral force fluctuation with respect to the toe angle is actually measured for each wheel using a wheel alignment measuring device.

[0008] Regarding the method of measuring the lateral force fluctuation value,
The lateral force fluctuation value of each wheel is measured by using the alignment measuring method disclosed in JP-A-2000-62639.

The vehicle travels straight and stably when the difference between the lateral force fluctuations of the front left and right wheels is minimized and the difference between the lateral force fluctuations of the rear left and right wheels is also minimized. Therefore, based on the characteristic of the lateral force variation with respect to the toe angle of each wheel, the difference between the common toe angle when the difference between the lateral force variations of the front left and right wheels is minimized and the difference between the lateral force variations of the rear left and right wheels is minimized. Find the difference between the common toe angles at the time. Then, the alignment of the vehicle is adjusted based on these common toe angles.

After the alignment adjustment, it is confirmed whether the vehicle travels straight and stably. Specifically, a stability factor is calculated based on a common toe angle of the front left and right wheels and the rear left and right wheels when the lateral force variation is minimized, and a vehicle motion model. Judge whether it exceeds. If the stability factor is equal to or greater than the reference value, the vehicle stably travels straight, but if it is less than the reference value, the vehicle cannot stably travel straight. Therefore, when the stability factor is smaller than the reference value, the common toe angle is calculated again. Specifically, the common toe angle of the front left and right wheels and the rear left and right wheels such that the stability factor is equal to or more than the reference value and the difference between the lateral force fluctuations of the front left and right wheels and the difference between the lateral force fluctuations of the rear left and right wheels are substantially minimized. Is calculated. And
By performing alignment adjustment based on this common toe angle,
The straight running performance of the vehicle is stabilized.

According to a second aspect of the present invention, for each of a plurality of vehicle motion models, a characteristic of a lateral force variation with respect to a toe angle of each wheel of the vehicle and a stability factor indicating stability of straight running of the vehicle are calculated. And the parameters necessary for the vehicle motion model, and for the specified vehicle motion model, read out the characteristic of the lateral force variation with respect to the toe angle of each wheel of the vehicle, and read out the characteristic of the lateral force variation with respect to the toe angle of each wheel. The common toe angle of the front left and right wheels that minimizes the difference between the lateral force fluctuations of the front left and right wheels, and the common toe angle of the rear left and right wheels that minimizes the difference between the lateral force fluctuations of the rear right and left wheels are calculated based on The parameters required to calculate a stability factor from the calculated common toe angles of the front left and right wheels and the rear left and right wheels are read, and the calculated common toe angles of the front left and right wheels and the rear right and left wheels are read out. Based on the parameters Calculate the stability factor, perform the alignment adjustment based on the common toe angle at that time when the stability factor is equal to or more than the reference value, and when the stability factor is less than the reference value, the stability factor is equal to or more than the reference value and A configuration including a step of calculating a common toe angle of the front left and right wheels and the rear left and right wheels such that the difference between the lateral force fluctuations of the front left and right wheels and the difference between the lateral force fluctuations of the rear left and right wheels is substantially minimized and performing alignment adjustment. Have been.

The alignment adjustment is performed not only while actually measuring the lateral force fluctuation of the vehicle using a wheel alignment measuring device or the like, but also storing a necessary vehicle motion model in advance and performing a simulation using this model. You may go.

Here, as a required vehicle motion model,
The characteristics of the lateral force variation with respect to the toe angle of each wheel of each vehicle and the parameters necessary for calculating the stability factor indicating the stability of straight running of each vehicle are stored. When the operator inputs data specifying a vehicle motion model such as a load applied to wheels, a toe angle, a camber angle, and the like,
The characteristics of the lateral force variation with respect to the toe angle of each wheel of the vehicle are read out, and the difference between the front to left and right wheels and the common toe angle of the front left and right wheels that minimizes the difference between the lateral force variations of the front left and right wheels is minimized. And the common toe angle of the rear left and right wheels is automatically calculated. And
It is determined whether or not these toe angles are optimal values so that the vehicle travels straight and stably.

Specifically, parameters necessary for calculating the stability factor are read from the calculated common toe angle, and the stability factor is calculated using the parameters. When the stability factor is equal to or greater than a reference value,
Since the vehicle travels straight and stably, the alignment is adjusted based on the common toe angle at that time. On the other hand, when the stability factor is less than the reference value, the straight running performance of the vehicle is not good. Therefore, it is necessary to calculate a new common toe angle. That is, the common toe angle of the front left and right wheels and the rear left and right wheels is calculated so that the stability factor is equal to or more than the reference value and the difference between the lateral force fluctuations of the front left and right wheels and the difference between the lateral force fluctuations of the rear left and right wheels are substantially minimized. I do. Then, the alignment is adjusted based on the common toe angle calculated in this manner.

[0015]

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

(Configuration of Wheel Alignment Measuring Apparatus)
FIG. 1 is a diagram showing a wheel alignment measuring device to which the present invention can be applied. The wheel alignment measuring device includes a mounting table 12 that is raised and lowered by a main lifting device 10, and a vehicle cradle 16 that is raised and lowered with respect to the mounting table 12 by a sub-elevating device 14.

Further, as shown in FIG. 2, the wheel alignment measuring device stores a measured value of the vehicle measured by, for example, the tire driving device 18, and performs a predetermined calculation based on the measured value. And a display device 82 for displaying the result calculated by the control device 80 and the like.

The mounting table 12 shown in FIG. 1 has four tire driving devices 18 for rotating and driving each wheel of the vehicle 20.
Is attached.

The tire driving devices 18 have the same configuration, and detect the load on the wheels and measure the lateral force fluctuation of the vehicle when the wheels are driven to rotate. Further, the tire driving device 18 is mounted on a turning device (not shown) that can turn around a vertical axis and outputs a signal indicating a turning angle. Then, the tire driving device 18 rotates each wheel, and the turning device turns around the vertical axis (the toe angle of the wheel changes), and the lateral force variation with respect to the toe angle is measured.

The mounting table 12 includes a tire driving device 1.
8 on both front and rear sides of the vehicle in the vehicle longitudinal direction.
And a drive mechanism is provided corresponding to each of the pair of wheel stopper plates 64. The pair of wheel stopper plates 64 are substantially flush with the upper surface of the mounting table 12 in the retracted state, and extend along the vehicle front-rear direction.
An end near the side 8 is rotatably supported by the mounting table 12.

Further, rods 74 are attached to four sides of the mounting table 12 corresponding to the four tire driving devices 18. The rod 74 is supported at one end thereof so as to be rotatable about a predetermined axis, and is configured to be extendable and contractible. A distance sensor 76 is attached to the other end of the rod 74. The distance sensor 76 is, for example, a non-contact type sensor that emits a laser beam to an object and receives the laser light reflected by the object to detect a distance from the object.

The rod 74 is manually rotated and expanded and contracted so that the distance sensor 76 faces the center of the wheel while the wheel is mounted on the tire driving device 18. Thus, the distance sensor 76 can detect a distance from a wheel mounted on the tire driving device 18. The distance sensor 76 is connected to the control device 80, and outputs a result of detecting a distance from the wheel to the control device 80.

Although not shown, an angle measuring device for measuring a camber angle is also provided. The angle measuring device is
The camber angle of each wheel is measured, and the measurement result is sent to the control device 8
Supply 0.

The control device 80 includes, for example, a CP (not shown).
The apparatus includes a U, a RAM, a ROM, a hard disk drive, and the like, and controls each device constituting the wheel alignment measuring device 1. Further, the control device 80 stores data necessary for calculating a stability factor described later.

Necessary data include data of a certain vehicle motion model, for example, a four-wheel load of a vehicle, an initial toe angle,
Data on camber angle, data on the amount of movement of the load with respect to the minute lateral G of the vehicle, change in toe angle and camber angle, cornering force (CF) against load, camber angle and slip angle of four wheels, and self-aligning torque (SAT) data, data on the initial load, camber angle, and slip angle of the peak value of the lateral fluctuation force generated when the tire passes over the step. Note that the small horizontal G
It is preferable to use a general default value for the data of the change in the load movement amount, the toe angle and the camber angle with respect to. Further, the control device 80 may use data actually observed by the tire driving device 18 or the like as necessary.

Using these data, the control unit 80 calculates the optimum toe angle, calculates the stability factor of the vehicle when the toe angle is set, and supplies the calculation result to the display unit 82. . The display device 82 includes, for example, a CRT, and displays a measurement value from the tire driving device 18, an adjustment direction of the attitude angle of the wheel, a calculation result of the control device 80, and the like.

(Measurement of lateral force fluctuation with respect to toe angle) In the wheel alignment measuring device configured as described above, the control device 80 sets the following every time the toe angle of the wheel is changed.
The lateral force fluctuation measured by the tire driving device 18 is stored.
The control device 80 also stores the measurement result of the lateral force variation with respect to the toe angle for the other wheels.

FIG. 3 is a diagram showing the relationship between the toe angle of each wheel and the lateral force variation when the front wheel left side is FL, the front wheel right side is FR, the rear wheel left side is RL, and the rear wheel right side is RR. is there. As shown in FIG. 3, the characteristics of the lateral force variation with respect to the toe angle are different for different wheels.

The most stable running condition of the vehicle is as follows.
This is when the difference between the lateral force fluctuations of the left and right wheels is the smallest. Therefore, in FIG. 3, the most stable traveling state of the vehicle is at a point where the characteristics of the wheels FL and FR intersect and a point where the wheels RL and RR intersect.
Therefore, the control device 80 calculates the toe angle when each of the above-described characteristics intersects, based on the stored lateral force variation with respect to the toe angle of each wheel.

The inventor of the present application measured the lateral force variation with respect to the toe angle for each wheel of a predetermined vehicle, and obtained the results shown in FIG. According to this measurement result, the wheel FL and the wheel F
The difference in the lateral force fluctuation of R was minimized when the toe angle was 0.0
5 [deg]. Also, the wheel RL and the wheel RR
The difference in the lateral force fluctuation was the smallest when the toe angle was 0.45
[Deg].

The control device 80 controls the above-mentioned turning device so that these toe angles are attained, and adjusts the alignment. At this time, the control device 80 can perform predetermined measurement on the vehicle whose alignment has been adjusted, and further store data necessary for calculating the stability factor.

(Calculation of stability factor)
The stability factor indicating the stability of the vehicle is calculated using the calculated toe angle of each wheel. As described above, even when the optimum toe angle of each wheel is obtained and the alignment is adjusted in accordance with the optimum toe angle, the straight traveling state of the vehicle may not be good due to variations in tire performance. Therefore, the control device 80 calculates the stability factor as follows in order to determine whether the calculated toe angle is an optimum value.

The stability factor when tire data of the load, camber, and toe angle of each wheel of a certain vehicle is given can be obtained as follows. Here, tire data is given as follows. CF = f (W, CA, SA) SAT = g (W, CA, SA) CF: Cornering force W: Wheel load CA: Camber angle (Camber Angle) SA: Slip angle (Slip Angle) SAT: Self-aligning torque (Self Aligning To
rque)

As shown in FIG. 5, the suffix numbers "1", "FL", "FR", "RL", and "RR" in this order.
"2", "3" and "4" are used.

First, at the time of going straight, the cornering force CF with respect to the steering angle α of the front shaft (front) is set.
And _F, the cornering force CF _R for α steering angle of the rear axle (rear) is determined.

[0036]

(Equation 1)

When the vehicle is going straight, CF _F = 0 and CF _R = 0. These values are substituted into Expressions (1) and (2), and the front slip angle α _F is obtained from Expression (1). The rear slip angle α _R is obtained from 2). Thereby, as the ground SA
As shown below, α _{1 to} α ₄ are obtained. α ₁ = α _F + T _oe1 α ₂ = α _F + T _oe2 α ₃ = α _R + T _oe3 α ₄ = α _R + T _oe4

Next, as the state for the micro lateral G (= 0.05 g), as shown in the following equation (3) and (4), the cornering force CF _F and CF _R of the front and rear with respect to the steering angle Ask. Incidentally, [Delta] W _f as load transfer front and rear, the [Delta] W _R, front and rear CA change as [Delta] CA _f, the [Delta] CA _R, [Delta] T _OEF, the [Delta] T _Oer used as toe angle change of the front and rear.

[0039]

(Equation 2)

The following equations (5) and (6) are substituted for the above equations (3) and (4). CF _F = 0.05 × (W ₁ + W ₂ ) (5) CF _R = 0.05 × (W ₃ + W ₄ ) (6)

From equation (4), the flow at the time of the small horizontal G is obtained.
Front slip angle α_FAnd rear slip angle α_RAsk for.
Thereby, as shown below, as the ground SA, α₁
~ Α _FourIs required. α₁= Α_F+ T_oe1+ ΔT_oef α_Two= Α_F+ T_oe2−ΔT_oef α_Three= Α_R+ T_oe3+ ΔT_oeR α_Four= Α_R+ T_oe4−ΔT_oeR

The lateral force fluctuations of equations (5) and (6) are the increments of α _F and α _R when a minute lateral G occurs (lateral G = 0.05 g) from straight traveling (lateral G = 0). , The equivalent cornering power C _pf for each of the front and rear,
C _pr can be determined. The equivalent cornering powers C _pf and C _pr are substituted into the equation of motion of the following equation (7) to determine the yaw rate gain γ.

[0043]

(Equation 3)

The variables at this time are as follows. m: vehicle mass V: speed F _f : front cornering force F _r : rear cornering force β: body slip angle I: yaw moment of inertia l _f : distance from front axis to center of gravity l _r : distance from rear axis to center of gravity θ : Handle angle λ: Overall gear ratio

For the yaw rate gain γ, the following equation
(8) stability factor F _stabAsk for.

[0046]

(Equation 4)

The controller 80 calculates a stability factor indicating the stability of the straight running of the vehicle as described above, and compares the calculated stability factor with a reference value. This reference value is a reference value indicating whether the vehicle travels straight and stably. When the calculated stability factor is equal to or larger than the reference value, it indicates that the straight traveling state is stable. Note that the method of deriving the stability factor described above is merely an example, and other derivation methods may be used. Further, another parameter may be used as long as the parameter indicates the straight running stability of the vehicle.

For example, in FIG. 4, the reference value of the stability factor of the vehicle exhibiting this characteristic is, for example, 1.829.
× 10 ⁻³ [sec ² / m ² ]. On the other hand, as described above, when the front toe angle is 0.05 [deg] and the rear toe angle is 0.45 [deg], the stability factor is 1.896 × 10 ⁻³ [sec ^2] / M ² ].

At this time, since the calculated stability factor exceeds the reference value, control device 80 determines that the straight running of the vehicle is stable. Therefore,
The vehicle whose alignment has been adjusted in this way can stably travel straight.

On the other hand, when the stability factor is smaller than the reference value, the vehicle cannot stably travel straight. Therefore, the control device 80 again obtains a point where the difference between the lateral force fluctuations of the front left and right wheels and the lateral force fluctuation of the rear left and right wheels becomes next smaller, and calculates the front and rear toe angles at that time. Then, a stability factor is calculated using the front and rear toe angles, and is compared with a reference value. When the stability factor is equal to or larger than the reference value, the controller 80 controls the turning device so that the front and rear toe angles become the values at this time, and performs alignment adjustment. When the stability factor is less than the reference value, a point where the difference between the lateral force fluctuations of the front left and right wheels and the lateral force fluctuation of the rear left and right wheels becomes the second smallest may be obtained again.

As described above, the control device 80 determines the toe angle at which the stability factor is equal to or greater than the reference value and the difference between the lateral force fluctuation of the front wheels and the lateral force fluctuation of the rear wheels is the smallest. I'm asking. As a result, the alignment can be adjusted so that the vehicle can travel straight and stably while taking into consideration the characteristics and the like of the actual individual tires.

The inventor of the present application calculated the stability factor for the vehicle described with reference to FIG. 4, and obtained the results shown in FIG. According to FIG. 6, the front toe angle (front total toe angle) is 0.05 [deg], and the rear toe angle (rear total toe angle) is 0.45 [de].
g], the stability factor is the reference value “100”
To “104”. At this time, the lateral force fluctuation value became “60” with respect to the reference value “100”, and decreased by 40%. Further, the yaw fluctuation during straight traveling was “50” with respect to the reference value “100”, which was a decrease of 50%. That is, it was found that the stability of the straight running of the vehicle was improved.

(Simulation) By measuring the lateral force fluctuation generated in the vehicle while adjusting the toe angle, or adjusting the toe angle again when the stability factor becomes smaller than the reference value, the work load is extremely high. Big. Therefore, a series of steps as described above may be simulated.

More specifically, the control device 80 includes, as a vehicle motion model of a plurality of vehicles, a characteristic of lateral force variation with respect to a toe angle of each wheel of each vehicle, and a stability factor indicating stability of straight running of the vehicle. And the parameters required to calculate. As a specific vehicle motion model, for example, the mathematical expressions and variables used in Expressions (1) to (8) correspond.

When the vehicle motion model is specified by the operator, the control device 80 reads out the characteristic of the lateral force fluctuation with respect to the toe angle of each wheel of the vehicle. In order to specify the vehicle motion model, the operator may input, for example, a load applied to wheels, a toe angle, a camber angle, and the like.

Similar to the above-described embodiment, the control device 80 determines the common toe angle at which the difference between the lateral force fluctuations of the front left and right wheels is minimized based on the characteristic of the lateral force fluctuation with respect to the toe angle of each wheel. A common toe angle at which the difference between the lateral force fluctuations of the rear left and right wheels is minimized, and a stability factor is also calculated. When the stability factor is equal to or greater than the reference value, control device 80 performs alignment adjustment based on the common toe angle at that time. When the stability factor is less than the reference value, the stability factor is equal to or more than the reference value, and the difference between the lateral force fluctuation of the front left and right wheels and the difference of the lateral force fluctuation of the rear left and right wheels is substantially minimized. A common toe angle for the wheels and the rear left and right wheels may be calculated, and the alignment may be adjusted based on the common toe angle at this time.

As a result, the operator can perform the alignment adjustment for improving the straight running stability of the vehicle by simulation without any trouble.

[0058]

According to the present invention, the common toe angle of the front left and right wheels which minimizes the difference in the lateral force fluctuation of the front left and right wheels and the rear left and right wheels based on the characteristics of the lateral force fluctuation with respect to the toe angle of each wheel. Calculate the common toe angle of the rear left and right wheels that minimizes the difference in lateral force fluctuation, perform alignment adjustment, calculate the stability factor based on the calculated common toe angle of each wheel and the vehicle motion model By checking whether or not the common toe angle is an optimum value, it is possible to perform an alignment adjustment to improve the straight running stability of the vehicle while taking into account the actual variation in the performance of each tire.

Further, the present invention provides a vehicle motion model
The characteristics of the lateral force variation with respect to the toe angle of each wheel of each vehicle and the parameters required to calculate the stability factor are stored, and the data corresponding to the specified vehicle motion model is read out, and the optimal data is obtained by simulation. By calculating the toe angle and performing the alignment adjustment, the burden on the operator can be reduced and the alignment adjustment that improves the straight running stability of the vehicle can be easily performed.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of a wheel alignment measuring device.

FIG. 2 is a block diagram illustrating a schematic configuration of a wheel alignment measurement device.

FIG. 3 is a diagram showing a relationship between a lateral force variation and a toe angle of each wheel when a front wheel left side is FL, a front wheel right side is FR, a rear wheel left side is RL, and a rear wheel right side is RR.

FIG. 4 is a diagram showing a result when a lateral force variation with respect to a toe angle is measured for each wheel of a predetermined vehicle.

FIG. 5 is a diagram illustrating that suffix numbers are assigned to wheels FL, FR, RL, and RR.

FIG. 6 is a diagram illustrating parameter values when a stability factor exceeds a reference value for a predetermined vehicle.

[Explanation of symbols]

 1 wheel alignment measuring device 18 tire driving device 80 control device

Claims (2)

[Claims] A characteristic of lateral force variation with respect to a toe angle of each wheel of a vehicle is measured, and based on the characteristic of lateral force variation with respect to a toe angle of each wheel, a difference between lateral force variations of front left and right wheels is determined to be minimum. Calculate the common toe angle of the front left and right wheels and the common toe angle of the rear left and right wheels that minimizes the difference in lateral force fluctuation between the rear left and right wheels, and adjust the alignment based on the calculated common toe angle of each wheel. Based on the calculated common toe angle of each wheel and the vehicle motion model when the alignment is adjusted, a stability factor indicating the stability of the straight running of the vehicle is calculated, and the stability factor is a reference. When the value is less than the value, the common toe angle of the front left and right wheels and the rear left and right wheels is set so that the stability factor is equal to or greater than the reference value and the difference between the lateral force fluctuations of the front left and right wheels and the difference between the lateral force fluctuations of the rear left and right wheels are substantially minimized. And adjust the alignment Alignment adjustment method for a vehicle. 2. A plurality of vehicle motion models, a characteristic of lateral force variation with respect to a toe angle of each wheel of each vehicle, and a parameter required to calculate a stability factor indicating stability of straight running of each vehicle. And, for the specified vehicle motion model, read out the characteristic of the lateral force variation with respect to the toe angle of each wheel of the vehicle. Based on the read out characteristic of the lateral force variation with respect to the toe angle of each wheel, Calculating a common toe angle of the front left and right wheels that minimizes the difference in lateral force variation between the left and right wheels, and a common toe angle of the rear left and right wheels that minimizes the difference in lateral force variation of the rear left and right wheels. Read out the parameters required to calculate the stability factor from the common toe angles of the front left and right wheels and the rear left and right wheels, based on the calculated common toe angles of the front left, right and rear right and left wheels, and the read parameters And stability When the stability factor is equal to or greater than the reference value, the alignment is adjusted based on the common toe angle at that time. When the stability factor is less than the reference value, the stability factor is equal to or greater than the reference value and An alignment adjustment method for a vehicle that calculates a common toe angle of the front left and right wheels and the rear left and right wheels so that the difference between the lateral force fluctuations of the left and right wheels and the difference between the lateral force fluctuations of the rear left and right wheels are substantially minimized.