JP6267440B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control device that controls the behavior of a vehicle by independently controlling a braking / driving force and a steering angle applied to each wheel of the vehicle.

In recent years, there has been an increasing interest in electric vehicles that use an electric motor as the power source of the vehicle. Attention has been focused not only on environmental aspects such as exhaust gas not being exhausted, but also on responsiveness and high degree of freedom of control by motor drive, and a control method that takes advantage of these features has been proposed. In particular, an in-wheel motor in which an electric motor is incorporated in a wheel has an advantage that the rotational speed and braking / driving force can be controlled for each wheel.
Generally, when a vehicle turns, a centrifugal force is generated on the vehicle body toward the outside of the vehicle and the vehicle body rolls. A control method for suppressing this roll is proposed in Patent Documents 1 to 3, for example. .

According to Patent Document 1, a roll moment is generated in the vehicle by controlling the braking / driving force in each wheel, and the roll of the vehicle body that occurs during turning is suppressed. An example of the vehicle seen from the side will be described with reference to FIG. Suspension instantaneous rotation center determined by the geometric position of the suspension is a vehicle in which both the front and rear wheels are located between the front and rear wheels. Is illustrated. When given the force X _f to brake the vehicle to the front wheel, when the angle between the straight line and the road surface connecting the suspension instantaneous center of rotation of the tire ground contact point and the front wheel and theta _f, the vehicle body through the suspension X _f Xtanθ _f The upward force is added. This force acts on the vehicle body at the suspension mounting position. In the same way, when given the force X _r to drive the vehicle to the rear wheel, when the angle between the straight line and the road surface connecting the suspension instantaneous center of rotation of the tire ground contact point and the front wheel and theta _r, the suspension to the vehicle body An upward force of X _r tanθ _f is applied. When a downward force is applied to the vehicle body via the suspension, a downward force is applied to the vehicle body by applying a driving force to the front wheels or a braking force to the rear wheels. Using this force, the roll is suppressed by controlling the braking / driving force of each wheel in accordance with the direction of the roll of the vehicle.

  In Patent Document 2, by detecting the state of the road surface, the roll control is stopped when the road surface condition is bad such as when the unevenness is large. In Patent Document 3, roll control is stopped when vehicle stability control such as ABS (anti-lock brake system) control or side slip control is executed.

Japanese Patent Laying-Open No. 2005-312190 Japanese Patent Laid-Open No. 2007-11083 JP 2007-131212 A

When the control is suddenly stopped during the roll control as in Patent Document 2 or Patent Document 3, the behavior of the vehicle may change suddenly, which may cause a problem in safety and driver comfort.
When performing roll control, if braking / driving force is applied without considering the tire load of each wheel, the braking / driving force of a specific tire may increase. If the resultant force of braking / driving force and lateral force in each tire exceeds the frictional force that can be generated by the tire, there is a risk that the tire will slip and hinder the running stability of the vehicle.

It is an object of the present invention to make the yaw angular velocity and the side slip angle as target values approximately equal in the case where the roll control is performed and the case where the roll control is not performed in the control for suppressing the roll of the vehicle. It is another object of the present invention to provide a vehicle control device that can reduce a change in vehicle behavior when the control is stopped, thereby improving safety and driver comfort.
Another object of the present invention is to prevent an increase in braking / driving force of a specific tire.

The vehicle control device according to the present invention applies left and right and left and right wheels 1, 2, 3, and 4 supported on a vehicle body 8 by a suspension 6 and applies driving force and braking force to the left, right and left and right wheels 1, 2, 3, and 4. The torque applying means 5 capable of independently controlling the driving torque and the braking torque of each of the wheels 1, 2, 3, 4 and the steering means 11 steered by the driver are mechanically independent. In the vehicle control device for controlling the vehicle 7 provided with the steering means 9 capable of
A braking / driving force control means 19a for controlling the torque applying means 5; a turning amount control means 12a for controlling the turning means 9; and a roll control means 18 for controlling the roll of the vehicle 7;
The roll control means 18 calculates the yaw angular speed and the side slip angle of the vehicle 7 according to the steering amount of the steering means 11 steered by the driver from the vehicle model, and sets it as the control target value, thereby making the yaw angular speed and the side slip. The ECU 13 calculates the braking / driving force and the steered amount of each wheel so that the angle is approximately equal between the case where the angle is suppressed by the roll control and the case where the angle is not suppressed, and the braking / driving force control means 19a and the Control the turning amount control means 12a ,
The roll control means 18, as the model of the vehicle, relates to the force that governs the movement in the longitudinal and lateral directions of the center of gravity of the vehicle and the rotational direction around the axis. (The force determined from the required longitudinal acceleration determined from the operation of the accelerator or the brake)), and the braking / driving force Xi (i = 1 to 4) of each wheel 1, 2, 3, 4 satisfies the following equation (2) Suppose,
X ₁ + X ₂ + X ₃ + X ₄ = X (2)
And wherein a call.
The phrase “so as to be approximately equal” means “within a range that is determined to the extent that the driver does not notice the behavior of the vehicle that occurs at the moment when the roll control is stopped”.

  According to the vehicle control device of this configuration, the roll control means 18 calculates the yaw angular velocity and the side slip angle of the vehicle 7 according to the steering amount of the steering means 11 steered by the driver from the vehicle model, and the control target value. Thus, the ECU 13 calculates the braking / driving force and the turning amount of each wheel so that the yaw angular velocity and the side slip angle are approximately equal between the case where the yaw angular velocity and the side slip angle are suppressed by the roll control. The braking / driving force control means 19a and the turning amount control means 12a are controlled. For this reason, the vehicle behavior change when the control is suddenly stopped during the roll control is small, and the safety and the driver's comfort are improved. In addition, in order to calculate the yaw angular velocity and the side slip angle of the vehicle 7 according to the steering amount from the vehicle model and set them as target values for control, by appropriately setting the vehicle model, the magnitude of the yaw angular velocity and the side slip angle can be set to roll Control that is approximately equal between the case of suppression by control and the case of non-suppression can be easily realized.

Specifically, the vehicle 7 includes an acceleration detection means 16 for detecting the longitudinal and lateral acceleration of the vehicle 7, a vehicle speed detection means 21 for detecting the speed of the vehicle 7, and a driver's steering. The steering angle detection means 11a for detecting the steering amount of the steering means 11, the accelerator amount detection means 14a for detecting the operation amount of the accelerator 14 operated by the driver, and the operation amount of the brake operation means 15 operated by the driver The roll control means 18 includes a vehicle front-rear direction and a lateral direction detected by the detection means 16, 11a, 14a, 15a so as to approach the target value. Using the acceleration in the direction, the speed of the vehicle 7, the steering amount of the steering means 11, the operation amount of the accelerator 14, and the operation amount of the brake operation means 15, the torque applying means 5 and the To control steering means 9 in each braking-driving force control unit 19a and the steering amount control means 12a.
Another device for measuring the roll angle of the vehicle 7 by using the lateral acceleration information of the acceleration sensor 16 composed of a G sensor or the like used for calculating the wheel load when calculating the force for suppressing the roll. The overall configuration can be simplified.

In this way, when the magnitude of the force against the roll is calculated by multiplying the magnitude of the lateral acceleration generated in the vehicle 7 by the coefficient, the roll control means 18 calculates from the longitudinal acceleration and the lateral acceleration generated in the vehicle. Calculated from the axial load at each wheel 1, 2, 3 and 4, the braking / driving force at each wheel 1, 2, 3 and 4, the turning angle at each wheel 1, 2, 3 and 4 and the axial load. The lateral force of the wheels 1, 2, 3, 4 is calculated sequentially so that the mutual difference between the braking / driving force, the resultant force of the lateral force, and the ratio of the axial load at each wheel 1, 2, 3, 4 is reduced. , 3 and 4, the target values of the braking / driving force and the turning angle may be determined.
As a result, the braking / driving force and the turning angle at each wheel 1, 2, 3, 4 can be controlled so that the difference between the tire load factors of each wheel 1, 2, 3, 4 is reduced. The braking / driving force of the vehicle 7 can be suppressed from increasing, and the running stability of the vehicle 7 is ensured. The "tire load factor" here refers to the ratio of the resultant force of braking / driving force and lateral force at each wheel 1, 2, 3, 4 and the product of the friction coefficient of the wheel tire and road surface and the axial load. Represents.

Thus, when controlling so that the mutual difference of each wheel 1, 2, 3, 4 becomes small, the said roll control means 18 is the said resultant force of the braking / driving force and lateral force in each wheel, The ratio of the product of the friction coefficient between the tire and the road surface at the wheels 1, 2, 3 and 4 and the axial load is sequentially calculated, and the braking / driving force and the steering at each wheel so that the difference between the ratios becomes small. The target value of the corner may be determined.
By estimating the friction coefficient between each wheel 1, 2, 3, 4 and the road surface, and considering the road surface friction coefficient in the calculation of the tire load factor, for example, a wheel having a small road surface friction coefficient in a situation such as a split μ road. Giving excessive braking / driving force and rudder angle can be prevented.

In the case of this configuration, the roll control means 18 includes road surface friction coefficient estimating means 24 for estimating the friction coefficient between the tire and the road surface in each of the wheels 1, 2, 3, and 4, and the road surface friction coefficient estimating means 24 is provided. The target value of the braking / driving force and the turning angle at each of the wheels 1, 2, 3, and 4 may be determined using the friction coefficient estimated in step (1).
By providing the road surface friction coefficient estimating means 24, the braking / driving force and the target value of the turning angle in each of the wheels 1, 2, 3, and 4 can be determined to be more appropriate values. The coefficient of friction between the tire and the road surface can be easily estimated by determining the slip ratio from, for example, the difference between the vehicle speed and the rotational speed of the drive wheels.

When the magnitude of the force against the roll for suppressing the roll generated in the vehicle is calculated by multiplying the magnitude of the lateral acceleration generated in the vehicle 7 by a coefficient, the roll control means 18 The driver can arbitrarily or selectively set a coefficient to be multiplied by the magnitude of the lateral acceleration generated in the vehicle 7 in order to calculate the magnitude of the force against the roll, by the coefficient input setting means 24 operable by the driver. You may do it.
In this way, when the driver can set the coefficient, for example, the degree of control effect can be adjusted according to the road surface condition or the driver's preference.

Further, the roll control means 18 uses a coefficient applied to the magnitude of lateral acceleration generated in the vehicle to calculate the magnitude of the force against the roll, and the vehicle speed detected by the vehicle speed detection means 21 and the You may make it have the coefficient change means 25 set automatically according to the steering angle which the driver | operator detected and detected by the steering angle detection means 11a.
Thus, by automatically changing the coefficient, for example, it is possible to automatically change to a completely different control effect during high speed running and low speed running.
Note that both the coefficient input setting means 24 and the coefficient changing means 25 may be provided together and selected using a switch or the like.

In the vehicle control device according to the present invention, the vehicle 7 includes a steering means 9 having at least front wheels 1 and 2 provided with a turning mechanism 9a capable of turning independently of the driver's steering. , 2 may be provided with a function capable of making an independent turning angle.
Further, the steering means 9 may be provided with a rear wheel steering mechanism 9b capable of steering the rear wheels 3, 4 in addition to the front wheel steering mechanism 9a. In this case, the rear wheel steering mechanism 9b may be provided with a function that allows the left and right wheels 3 and 4 to have independent steering angles.
Even in a vehicle including such a front wheel steering mechanism 9a and a rear wheel steering mechanism 9b, the effects of the present invention can be effectively obtained.

In the present invention, in the vehicle 7, the drive source 5a of the torque applying means 5 may be an electric motor. For example, the torque applying means 5 may be an in-wheel motor device.
When the drive source 5a of the torque applying means 5 is an electric motor, the torque can be controlled with good responsiveness and finely.

The vehicle control device according to the present invention can control the driving torque and braking torque of each wheel independently by applying driving force and braking force to the left and right and left and right wheels supported by the vehicle body by the suspension and the left and right and front and rear wheels. In a vehicle control apparatus for controlling a vehicle comprising a torque providing means and a steering means capable of at least front wheel turning that is mechanically independent of steering by a driver.
A braking / driving force control means for controlling the torque application means, a turning amount control means for controlling the turning means, and a roll control means for controlling the roll of the vehicle,
The roll control means calculates the yaw angular velocity and the side slip angle of the vehicle according to the steering amount of the steering means steered by the driver from the vehicle model and sets the control target values, thereby increasing the yaw angular velocity and the side slip angle. The control is performed by the braking / driving force control means and the steered amount control means so as to be approximately equal between the case where it is suppressed by roll control and the case where it is not suppressed ,
The roll control means, as a model of the vehicle, relates to the force that governs the movement in the longitudinal and lateral directions of the vehicle center of gravity and the rotational direction around the axis, and X represents the total braking / driving force of the vehicle (where X is the accelerator of the driver). Or a force determined from the required longitudinal acceleration determined from the operation of the brake), and the braking / driving force Xi (i = 1 to 4) of each wheel satisfies the above formula (2). The change in vehicle behavior when control is suddenly stopped is small, and safety and driver comfort are improved.

Moreover, it can suppress that a specific tire load factor becomes large by controlling the braking / driving force and steering angle of each wheel so that the mutual difference of the tire load factor of each wheel may become small. Furthermore, by estimating the friction coefficient between each wheel and the road surface, and considering the road surface friction coefficient in the calculation of the tire load factor, excessive braking / driving force is applied to tires with a small road surface friction coefficient under conditions such as split μ roads. And giving a rudder angle can be prevented.
When calculating the force to suppress the roll, it is not necessary to provide another device for measuring the roll angle of the vehicle by using the lateral acceleration information of the G sensor used for calculating the wheel load, and the entire configuration Can be simplified.
In addition, by allowing the driver to set a coefficient for calculating the force for suppressing the roll, the control effect can be adjusted according to, for example, the road surface condition or the driver's preference. Similarly, by automatically setting the coefficient in accordance with the vehicle speed and the steering angle, it is possible to automatically change the control effect to completely different, for example, at high speed and low speed.

It is explanatory drawing which combined the top view of the vehicle used as the control object in one Embodiment of this invention, and the block diagram of the conceptual structure of a vehicle control apparatus. It is principle explanatory drawing shown from the side of the vehicle. It is a figure which shows the general relationship between a slip ratio and a road surface friction coefficient.

  An embodiment of the present invention will be described with reference to the drawings. The embodiment will be described by taking a four-wheel vehicle in which the braking / driving force and the turning angle of each wheel can be freely controlled as an example. In FIG. 1, the left and right wheels 1 and 2 as front wheels and the left and right wheels 3 and 4 as rear wheels are all attached to a torque applying means 5 comprising an in-wheel motor device, and a suspension 6 (FIG. 2). ) And the torque applying means 5 of FIG. The in-wheel motor device serving as the torque applying means 5 includes a wheel bearing (not shown) that supports the wheels 1, 2, 3, and 4, an electric motor 5a serving as a drive source, and rotation of the electric motor 5a described above. It consists of a decelerator that decelerates and transmits to the rotating wheel of the wheel bearing. Since this torque applying means 5 is an electric motor 5a, both the driving force and the braking force can be controlled, and are provided individually for each wheel 1, 2, 3, 4. The driving torque and braking torque of each wheel can be controlled independently. The electric motor 5a is a synchronous motor or an induction motor. Each of the wheels 1, 2, 3, and 4 is provided with a brake (not shown) that performs braking separately from the braking force by the electric motor 5a. The torque applying means 5 may be an internal combustion engine and a brake.

  For the left and right wheels 1 and 2 serving as front wheels, a steering mechanism 9a capable of independently turning the left and right wheels 1 and 2 is provided. This steering mechanism 9a is of a so-called steer-by-wire type that is mechanically independent from the steering wheel, which is the steering means 11 that is steered by the driver. The steering mechanism 9a includes, for example, a steering motor and a toe angle adjustment motor (both not shown), and can drive the left and right wheels 1 and 2 independently by driving these motors. is there. Further, the left and right wheels 3 and 4 as rear wheels can be steered independently by being provided with a steering mechanism 9b. These front and rear steering mechanisms 9a, 9b constitute the entire steering means 9 of the vehicle 7.

  The steering angle by the driver's operation of the steering means 11 is detected by a steering angle detection means 11 a including a steering angle sensor provided in the steering means 11, and is sent from the steering controller 12 to the ECU 13. The ECU 13 is a main electric control unit that performs integrated control and cooperative control of the entire vehicle 7, and includes a programmed microcomputer and an electronic circuit (not shown). Similarly, the operation amounts of the accelerator 14 and the brake operation means 15 each composed of a pedal or the like are also sent to the ECU 13 from the accelerator amount detection means 14a and the brake amount detection means 15a for detecting these operation amounts, respectively. . Information on the longitudinal acceleration and the lateral acceleration generated in the vehicle 7 is detected by the acceleration detection means 16 including a G sensor provided in the vehicle 7 and sent to the ECU 13. The vehicle speed is sent from the vehicle speed detection means 21 such as a vehicle speed sensor provided in the vehicle 7 to the ECU 13. The vehicle speed detection means 21 may calculate the vehicle speed from a rotation detection value of a rotation sensor provided in each electric motor 5a or wheel bearing or the like.

  The ECU 13 determines the braking / driving force and the turning angle of each of the wheels 1, 2, 3, and 4 based on the sent information, and provides torque applying means 5 including an in-wheel motor device, and the rotation of the front wheels. The steering mechanism 9a and the rear wheel steering mechanism 9b are controlled. The turning amount of each of the turning mechanisms 9 a and 9 b is controlled by a turning amount control means 12 a provided in the steering controller 12 based on a turning amount command sent from the ECU 13.

  Specifically, the ECU 13 sends a basic torque command from the accelerator operation amount and the brake operation amount sent from the accelerator amount detection means 14a and the brake amount detection means 15a to the torque application means 5 composed of an in-wheel motor device for each wheel. Roll control means for controlling the roll of the vehicle 7 by adding a correction amount to the torque command generated by the basic drive control means 17. 18 is provided.

  The torque command output from the ECU 13 is given as a drive current to the electric motor 5a of each torque applying means 5 via the inverter device 19, respectively. The inverter device 19 is an inverter (not shown) that converts the DC power of the battery 20 into three-phase AC corresponding to the electric motor 5a, and a motor controller that controls the current of the inverter by PWM control, vector control, or the like. Driving force control means 19a.

  The roll control means 18 calculates the yaw angular velocity and the side slip angle of the vehicle 7 according to the steering amount of the steering means 11 that the driver steers, that is, the steering amount detected by the steering angle detection means 11a, from the vehicle model. The torque applying means 5 and the turning mechanisms 9a and 9b are controlled via the braking / driving force control means 19a and the turning amount control means 12a, respectively, so as to approach the target value. In this control, the longitudinal and lateral accelerations of the vehicle detected by the detection means 16, 21, 11a, 14a, 15a, the vehicle speed, the steering amount of the steering means 11, the operation amount of the accelerator 14, the brake operation The operation amount of the means 15 is used.

The roll control means 18 calculates the yaw angular velocity and the side slip angle of the vehicle 7 according to the steering amount of the steering means 11 that is steered by the driver from the vehicle model and sets it as the control target value, so that the yaw angular velocity and the side slip are calculated. The braking / driving force control means 19a and the steered amount control means 12a are controlled so that the size of the corner is approximately equal between when the angle is suppressed by roll control and when the angle is not suppressed.
The phrase “so as to be approximately equal” means “within a range that is determined to the extent that the driver does not notice the behavior of the vehicle that occurs at the moment when the roll control is stopped”.

  The roll control unit 18 includes a target value calculation unit 23, a road surface friction coefficient estimation unit 24, and a coefficient change unit 25. The target value calculation unit 23 detects the steering amount detected by the steering angle detection unit 11a. The yaw angular velocity and the side slip angle of the vehicle 7 corresponding to the above are calculated from the vehicle model and set as the control target values.

  More specifically, the roll control means 18 will be described later with calculation formulas, but has the following functions. That is, the roll control means 18 calculates the magnitude of the force against the roll for suppressing the roll generated in the vehicle in the vehicle model by multiplying the magnitude of the lateral acceleration generated in the vehicle by a coefficient.

  Further, the roll control means 18 is configured to calculate the axial load at each wheel 1, 2, 3, 4 calculated from the longitudinal acceleration and lateral acceleration generated in the vehicle, the braking / driving force at each wheel, the turning angle at each wheel, The lateral force calculated from the axial load is sequentially calculated, and the braking / driving force at each wheel is reduced so that the difference between the braking / driving force at each wheel, the resultant force of the lateral force, and the ratio of the axial load is reduced. Determine the target value of the turning angle.

  In this case, the roll control means 18 includes the resultant force of the braking / driving force and lateral force at each of the wheels 1, 2, 3 and 4, the friction coefficient between the wheel and the road surface at each wheel, and the axial load. The ratio of the product of the two is sequentially calculated, and the target values of the braking / driving force and the turning angle at each wheel are determined so that the difference between the ratios becomes small.

Further, the roll control means 18 includes road surface friction coefficient estimating means 24 for estimating the friction coefficient between the wheel and the road surface in each of the wheels 1, 2, 3 and 4, and is estimated by the road surface friction coefficient estimating means 24. Using the friction coefficient, the braking / driving force and the target value of the turning angle in each of the wheels 1, 2, 3, and 4 are determined.

  The roll control means 18 is operated by operating the coefficient input setting means 26 that allows the driver to operate a coefficient that multiplies the magnitude of the lateral acceleration generated in the vehicle in order to calculate the magnitude of the force against the roll. Has a function that can be set arbitrarily or selectively. The coefficient input setting unit 24 includes, for example, an operation screen key switch or dial provided on the console of the driver's seat.

Further, the roll control means 18 may be provided with the coefficient changing means 25 for automatically changing the coefficient. That is, the coefficient applied to the lateral acceleration generated in the vehicle to calculate the magnitude of the force against the roll is detected by the vehicle speed detected by the vehicle speed detecting means 21 and the steering angle detecting means 11a. Coefficient changing means 25 may be provided that is automatically set according to the steering angle operated by the driver.
The coefficient changing means 25 and the coefficient input setting means 24 may be switched to function.

Next, a vehicle model used in the roll control means 18 and a more specific processing function of the roll control means 18 will be described. Although a planar two-degree-of-freedom model will be described as a vehicle model, the present invention is not limited to a specific model.
For the forces governing the motion in the longitudinal and lateral directions of the vehicle center of gravity and the rotational direction around the axis, X is the total braking / driving force of the vehicle, Y is the total lateral force, and M is the yaw moment. , 4 braking / driving force Xi (i = 1 to 4), lateral force of each wheel 1, 2, 3, 4 is Y _i , front and rear wheel treads are d _f and _dr , and front and rear wheel axle distance is l _f , L _r , these must satisfy the following equation.

  However, X is a force determined from the required longitudinal acceleration determined from the driver's operation of the accelerator 14 or the brake 15. The lateral force Y and the moment M determine a target response of the vehicle to the driver's steering and are obtained as forces necessary for the response. Equations (4) and (5) are the relationship equation for the side-slip motion in the vehicle plane and the relationship equation for the yaw motion.

Equation (4) (5) sideslip angle β and the yaw rate r of the vehicle corresponds to the response of the target vehicle to the steering angle [delta] _h of the driver. m is the vehicle weight and V is the vehicle speed. Equations (6) and (7) are vehicle response functions, which are obtained from a two-degree-of-freedom model of a vehicle assuming a linear tire. Using equations (6) and (7), the side slip angle β and yaw angular velocity r of the vehicle with respect to the driver's steering angle are calculated. Here, K _f and K _r are the cornering powers of the front wheels and the rear wheels, respectively.

Next, equation (8) is considered as a relational expression for performing roll control.

In order to suppress the roll generated in the vehicle 7, the force generated by the braking / driving force of each wheel is applied to the vehicle through the suspension 6. The right side of equation (8) is a reverse value obtained by multiplying the roll moment acting on the vehicle body by the coefficient α with the lateral acceleration generated in the vehicle. The coefficient α is a value between 0 and 1. By changing the coefficient α, the magnitude of the force for suppressing the roll can be changed. The coefficient changing unit 25 changes the coefficient α. G _y indicates lateral acceleration, and h _s indicates the height of the center of gravity. The first term on the left side is a moment acting through the suspension 6 by the braking / driving force of the front wheels. d _sf is the distance between the mounting positions of the left and right suspensions 6, 6 on the front wheels of the vehicle, and θ _f is formed by a straight line connecting the tire ground contact point of the wheels 1, 2 as the front wheels and the rotation center of the suspension 6 and the road surface. It is a horn. Similarly, the second term on the left side is a moment acting through the suspension 6 by the braking / driving force of the wheels 2 and 2 as rear wheels. d _sr is the distance between the mounting positions of the left and right suspensions 6, 6 on the wheels 3, 4 as the rear wheels of the vehicle 7, and θr is the rotation of the suspension 6 and the tire ground contact point of the wheels 2, 2 as the rear wheels. This is the angle between the straight line connecting the centers and the road surface.

Since the expressions (1), (2), (3), and (8) are the restraining conditions of the braking / driving force and lateral force of the wheels 1, ₂ , ₃ , and ₄ , for example, X ₂ , X ₃ , X ₄ , Y ₄ Is treated as a dependent variable, X ₂ , X ₃ , X ₄ , and Y ₄ can be expressed as functions of X ₁ , Y ₁ , Y ₂ , and Y ₃ as follows.

したがって、Ｘ_１，Ｙ_１，Ｙ_２，Ｙ_３を求めることで各輪の制駆動力および横力のすべてが求まる。

Accordingly, by determining X ₁ , Y ₁ , Y ₂ and Y ₃ , all of the braking / driving force and lateral force of each wheel can be determined.

Next, in order to equalize the tire load factors of the four wheels, an evaluation function J given by the following equation is defined as follows.

The right side of equation (13) is the square sum of the tire load factors, and the denominator is the road surface friction coefficient μ _i of each wheel.
And shows the product of the wheel load Z _i, molecule represents the resultant force of the longitudinal force X _i and the lateral force Y _i of each wheel.
Here, the following equations (14), (15), and (16) are shown as an example when estimating the road surface friction coefficient μ _i of each wheel.

I is a moment of inertia for one wheel including a wheel and a motor driven by the electric motor 5a. Ω _i is the rotational speed of each wheel, T _mi is the motor driving torque of each wheel, r is the tire rotation radius, and λ _i is the slip ratio. From equations (14), (15), and (16), the sequential slip ratio λ _i and the friction coefficient μ _i are obtained. Since the relationship between the slip ratio λ and the friction coefficient μ is generally represented by a curve as shown in FIG. 3, the maximum value of the friction coefficient can be estimated from the relationship between the obtained slip ratio λ _i and the friction coefficient μ _i . The maximum value of the estimated friction coefficient is used as the road surface friction coefficient μ _i in equation (13).

Each wheel load is obtained by the following relational expressions (17) to (20). Each wheel load Z _i is calculated by detecting longitudinal acceleration Gx and lateral acceleration G _y and using front and rear roll rigidity ratios K _f , K _r , sprung weight m _s , and center of gravity height H _s .

Next, minimizing the evaluation function J is obtained by solving the equations (21) to (24).

X ₁ , Y ₁ , Y ₂ , and Y ₃ obtained here are braking / driving force or lateral force that equalizes the tire load factor of each wheel during roll control. Further, the remaining X ₂ , X ₃ , X ₄ , and Y ₄ are obtained by substituting the obtained X ₁ , Y ₁ , Y ₂ , and Y ₃ into the equations (9) to (12).

Finally, the steering angle δ _i of each wheel for generating the lateral force Y _i is obtained. The steering angle δi of each wheel can be obtained from equations (25) to (28) using the side slip angle and lateral force of the vehicle 7 assuming a linear tire. K _i is a non-linear cornering power having load dependency.

  The vehicle is controlled using the braking / driving force and the steering angle of each wheel 1, 2, 3, 4 obtained from the above. The control shown in this embodiment is performed by sequentially executing the above processing.

  According to the vehicle control device of this configuration, the roll control means 18 calculates the yaw angular velocity and the side slip angle of the vehicle 7 according to the steering amount of the steering means 11 steered by the driver from the vehicle model, and the control target value. Thus, the braking / driving force control means 19a and the steered amount control means 12a are set so that the yaw angular velocity and the side slip angle are approximately equal between the case where the yaw angular velocity and the side slip angle are suppressed by the roll control. Let control take place. For this reason, the vehicle behavior change when the control is suddenly stopped during the roll control is small, and the safety and the driver's comfort are improved. In addition, in order to calculate the yaw angular velocity and the side slip angle of the vehicle 7 according to the steering amount from the vehicle model and set them as target values for control, by appropriately setting the vehicle model, the magnitude of the yaw angular velocity and the side slip angle can be set to roll Control that is approximately equal between the case of suppression by control and the case of non-suppression can be easily realized.

  Moreover, when calculating the force which suppresses a roll, since the lateral acceleration information of the acceleration sensor 16 which consists of G sensor used for calculation of a wheel load is used, another apparatus for measuring the roll angle of the vehicle 7 is provided. There is no need, and the entire configuration can be simplified.

  The roll control means 18 resists the roll in order to calculate the magnitude of the force against the roll for suppressing the roll in the vehicle model by multiplying the magnitude of the lateral acceleration generated in the vehicle 7 by a coefficient. The magnitude of the force can be determined easily and appropriately. In addition, by appropriately changing the coefficient, the magnitude of the force resisting the roll in the vehicle model can be easily changed, and the control characteristics can be easily changed.

  The roll control means 18 sequentially calculates the axial load, braking / driving force, and lateral force at each wheel 1, 2, 3, 4, and the resultant force of the braking / driving force and lateral force at each wheel and the shaft. The target values of the braking / driving force and the turning angle in each wheel are determined so that the mutual difference in the load ratio is small. Therefore, the braking / driving force and the turning angle in each wheel 1, 2, 3, 4 can be controlled so that the mutual difference in the tire load factor of each wheel 1, 2, 3, 4 is small, An increase in braking / driving force can be suppressed, and traveling stability of the vehicle 7 is ensured.

  The roll control means 18 sequentially calculates the ratio of the product of the resultant force of braking / driving force and lateral force at each wheel 1, 2, 3, 4 and the friction coefficient between the tire and the road surface and the axial load. The wheels 1, 2, 3, and 4 are determined so that the difference between the ratios becomes small. Thus, by estimating the friction coefficient with the road surface and considering the road surface friction coefficient in the calculation of the tire load factor, for example, in a situation such as a split μ road, an excessive braking / driving force or steering force is applied to a tire with a small road surface friction coefficient. It can prevent giving a corner.

  In this configuration, since the roll control means 18 includes the road surface friction coefficient estimation means 24, the braking force and the target value of the turning angle at each wheel 1, 2, 3, 4 are set to more appropriate values. Can be determined. The coefficient of friction between the tire and the road surface can be easily estimated, for example, by obtaining the slip ratio from the vehicle speed and the rotational speed of the drive wheels.

  When the magnitude of the force against the roll for suppressing the roll is calculated by multiplying the coefficient α as described above, the coefficient α is calculated by the driver by the coefficient input setting means 26 that can be operated by the driver. In the case where it can be arbitrarily or selectively set, for example, the degree of control effect can be adjusted in accordance with the road surface condition or the driver's preference.

  Further, when the roll control means 18 includes coefficient changing means 25 that automatically sets the coefficient according to the speed of the vehicle and the steering angle operated by the driver, for example, during high speed running and low speed running Can automatically change to a completely different control effect.

DESCRIPTION OF SYMBOLS 1, 2 ... Wheel 5 ... Torque provision means 5a ... Electric motor 6 ... Suspension 7 ... Vehicle 8 ... Vehicle body 9 ... Steering means 9a ... Steering mechanism 9b ... Rear wheel steering mechanism 11 ... Steering means 11a ... Steering angle detection means 12 ... Steering controller 12a ... Steering amount control means 13 ... ECU
14 ... Accelerator 14a ... Accelerator amount detection means 15 ... Brake operation means 15a ... Brake amount detection means 16 ... Acceleration detection means 18 ... Roll control means 19 ... Inverter device 19a ... Braking / driving force control means 23 ... Target value calculation means 24 ... Road surface Friction coefficient estimating means 25 ... coefficient changing means

Claims (11)

The left and right and left and right wheels supported by the vehicle body by the suspension, the torque applying means for applying driving force and braking force to the left and right and left and right wheels and independently controlling the driving torque and braking torque of each wheel, and the driver In a vehicle control apparatus for controlling a vehicle comprising a steering means capable of at least front wheel steering that is mechanically independent of the steering means for steering,
A braking / driving force control means for controlling the torque application means, a turning amount control means for controlling the turning means, and a roll control means for controlling the roll of the vehicle,
The roll control means calculates the yaw angular velocity and the side slip angle of the vehicle according to the steering amount of the steering means steered by the driver from the vehicle model and sets the control target values, thereby increasing the yaw angular velocity and the side slip angle. The control is performed by the braking / driving force control means and the steered amount control means so as to be approximately equal between the case where it is suppressed by roll control and the case where it is not suppressed ,
The roll control means, as a model of the vehicle, relates to the force that governs the movement in the longitudinal and lateral directions of the vehicle center of gravity and the rotational direction around the axis, and X represents the total braking / driving force of the vehicle (where X is the accelerator of the driver). Or a force determined from the required longitudinal acceleration determined from the operation of the brake), and the braking / driving force Xi (i = 1 to 4) of each wheel satisfies the following formula (2):
X ₁ + X ₂ + X ₃ + X ₄ = X (2)
Vehicle control device according to claim and this.   2. The vehicle control device according to claim 1, wherein the roll control means includes an axial load at each wheel calculated from a longitudinal acceleration and a lateral acceleration generated in the vehicle, a braking / driving force at each wheel, and a turning angle at each wheel. And the lateral force calculated from the axial load, and the braking / driving force at each wheel so that the difference between the braking / driving force at each wheel, the resultant force of the lateral force and the ratio of the axial load is small. And a vehicle control device for determining a target value of the turning angle. 3. The vehicle control device according to claim 2 , wherein the roll control means includes: the resultant force of braking / driving force and lateral force at each wheel; a friction coefficient between the wheel and the road surface at each wheel; and the axial load. A vehicle control device that sequentially calculates product ratios and determines target values of braking / driving force and turning angle at each wheel such that a difference between the ratios becomes small. 4. The vehicle control apparatus according to claim 3, wherein the roll control means includes road surface friction coefficient estimating means for estimating the friction coefficient between a wheel and a road surface in each wheel, and the friction estimated by the road surface friction coefficient estimating means. A vehicle control device that determines a target value of the braking / driving force and the turning angle in each wheel using a coefficient.   5. The vehicle control device according to claim 1, wherein the roll control unit is configured to generate a lateral force generated in the vehicle, the magnitude of the force resisting the roll for suppressing the roll generated in the vehicle. A vehicle control device that calculates the magnitude of acceleration by a coefficient.   6. The vehicle control device according to claim 5, wherein the roll control means is operable by a driver for a coefficient that is multiplied by a lateral acceleration generated in the vehicle in order to calculate a magnitude of a force that resists the roll. A vehicle control device that can be arbitrarily or selectively set by a driver using a coefficient input setting means. The vehicle control device according to claim 5, wherein the roll control means, the coefficient applied to the magnitude of the lateral acceleration generated in the vehicle in order to calculate the magnitude of the force against the roll, detecting drive speed detecting means vehicle control device having a coefficient changing means for setting automatically depending on the steering angle operation of the detected driver's speed and steering rudder angle detecting means of the vehicle is. The vehicle control device according to any one of claims 1 to 7 , wherein the steering means has a function capable of making the left and right wheels have independent turning angles for at least front wheels. apparatus.   9. The vehicle control device according to claim 1, wherein the turning means includes a rear wheel turning mechanism capable of turning a wheel of a rear wheel.   The vehicle control device according to any one of claims 1 to 9, wherein a drive source of the torque applying means is an electric motor.   The vehicle control device according to claim 10, wherein the torque applying means is an in-wheel motor device.

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