JP2015150953A - vehicle motion control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a constitution of motion control so as to obtain a more effective control effect by considering a tire grounding state (a friction state of a road surface and a ground load of the tire) in a vehicle having both control means with underbody control and control means with air current control for motion control of the vehicle.SOLUTION: A vehicle motion control device comprises: first control means which controls the motion state of a vehicle by controlling braking/driving force; second control means which controls the motion state of the vehicle by controlling air force acting on the vehicle body; grounding state detection means which detects the grounding state in at least one control wheel of the first control means; and control contribution degree changing means which changes the degree of contribution of the first control means and the degree of contribution of the second control means in the control of the motion state on the basis of the detected grounding state.

Description

  The present invention relates to a vehicle motion control device that controls the motion of a vehicle such as an automobile, and more specifically, a system for controlling vehicle motion by controlling braking / driving force and / or tire force generated on wheels, and a vehicle body. The present invention relates to a device for controlling the movement of a vehicle equipped with a system for controlling the vehicle movement by controlling the airflow acting on the vehicle.

  As is well known in the field of vehicle motion control for automobiles, etc., the motion of the running vehicle (movement of the vehicle body in the yaw direction, roll direction, pitch direction, etc.) is the braking / driving force on each wheel of the vehicle. Control (braking / driving force distribution control) and aerodynamic control (airflow control, aerodynamic control, air spoiler control) caused by the state of airflow around the vehicle body. Therefore, in the past, various types of braking / driving force distribution control means and airflow / aerodynamic control means have been proposed in vehicles, and a technique for stabilizing the motion or behavior of the vehicle has been proposed. Both driving force distribution control means and airflow / aerodynamic control means are mounted, and a configuration for coordinating both control means has also been proposed. For example, in Patent Document 1, in a vehicle equipped with driving force distribution control means and airflow control means, in order to avoid control interference when the driving force distribution control means and airflow control means operate simultaneously. On the basis of the control state of one control means, a configuration has been proposed in which the control gain of the control state of the other control means is changed to coordinate both controls. As an example of aerodynamic control, Patent Document 2 discloses a configuration in which yaw motion due to cross wind is reduced using a side spoiler and an end spoiler that can control the aerodynamic characteristics provided on the outer surface of the vehicle body. Control configurations for optimizing the vehicle posture at the time of going straight and turning have been proposed. In the braking / driving force distribution control, parameters such as a wheel ground load value and a road friction coefficient value are used. As an example of a method for detecting such a parameter, Patent Document 4 discloses a vehicle. A method for estimating a road surface friction coefficient from a ground contact area of a tire estimated based on a detection value of a ground load sensor provided on each wheel and a vehicle acceleration is disclosed in Patent Document 5, in which a ground contact load of a wheel is estimated from a suspension stroke. Each method has been proposed.

JP 08-099550 A JP 06-321143 A JP 06-286670 A JP2007-253677 JP2007-240392A

  By the way, of the vehicle motion control as described above, in the braking / driving force distribution control, a moment is generated in the vehicle body by the frictional force between the wheel and the road surface, and the control of the motion is achieved. The fact that a significant frictional force (tire force or road surface reaction force) can be generated is a prerequisite for control execution. However, depending on the contact condition between the wheel and the road surface, especially when the friction coefficient of the road surface is very low or the ground contact load of the wheel is very small, the friction force becomes small. It may become difficult to occur and the control effect may be reduced.

  More specifically, in vehicle motion control using tire force such as braking / driving force distribution control, basically, braking / driving force (tire longitudinal force) distributed to each wheel or steering is used. By controlling the generated tire lateral force, the balance of the road surface reaction force generated between the tire and the road surface is adjusted, and the adjusted tire force is transmitted from each wheel to the vehicle body to thereby adjust the vehicle body force. A moment that controls the direction is generated. Therefore, in a traveling vehicle, for example, in a state where a crosswind is blowing near the tunnel exit of an expressway, it is difficult to maintain a straight traveling state as it is due to the action of a crosswind force (external force). In such a case, braking / driving force distribution control and / or steering lateral force control (hereinafter referred to as tire suspension control is “suspension control”) so that a moment that cancels external force that changes the direction of the vehicle body acts on the vehicle body. In this case, the straight traveling state is maintained. That is, in the “suspension control”, the control moment is generated by the tire force. However, tire force is determined by the product of the coefficient of friction between the road surface and the contact surface of the tire (ground contact surface) and the vertical load of the tire (ground contact load), and there is a limit to the amount of friction force that can be generated. There is a limit value of such tire force, and when the friction coefficient or ground contact load decreases for some reason (for example, when the road surface friction coefficient such as snowy road, rainy weather, dirt, etc. is low, or the lift generated in the vehicle by the air current is large. When the upward force acts on the vehicle body, the ground contact load of the tire is reduced). Therefore, when the tire force limit value decreases, such as when the road surface immediately after exiting the tunnel is a snowy road or an ice burn, or when the vehicle body is beaten by a strong oblique crosswind, a sufficiently large control moment Cannot occur, and the target motion control cannot be sufficiently achieved. In such a case, airflow control or aerodynamic control that does not rely on tire force is more effective than suspension control that relies on tire force.

  Thus, one object of the present invention is, as described above, in a vehicle provided with both a control means based on "suspension control" and a control means based on aerodynamic control or airflow control for vehicle motion control. In consideration of the ground contact state of the tire (the friction state between the wheels and the road surface, the ground contact load of the tire), the configuration of the motion control is improved so that the control effect can be obtained more effectively.

  According to the present invention, the above-described problem is a vehicle motion control device for controlling the motion state of a vehicle, the first control means for controlling the motion state of the vehicle by controlling the braking / driving force, and the vehicle body. Second control means for controlling the motion state of the vehicle by controlling the acting aerodynamic force; ground contact state detection means for detecting a ground contact state in a control wheel of at least one first control means; Achieved by a device including a control contribution degree changing means for changing the degree of contribution of the first control means and the degree of contribution of the second control means in the control of the movement state based on the detected grounding state. Is done.

  In the above configuration, the control of the “vehicle motion state” that is the object of the device of the present invention may be any vehicle motion control or behavior control, and specifically, the yaw direction and pitch of the vehicle body. Control for correcting the direction of the vehicle body by applying a moment (control moment) to the vehicle body in the yaw direction, pitch direction, and / or roll direction, such as behavior stabilization control in the direction and roll direction. The “first control means” is a control means for executing the motion control or behavior control as described above, and by adjusting the braking / driving force of each wheel or adjusting the steering angle of each wheel, This is a means for controlling the tire force (front / rear force, lateral force) of each wheel (suspension control) and generating a control moment. The “second control means” executes the motion control or behavior control as described above. Control means for controlling the aerodynamic force acting on the vehicle body (aerodynamic control) by controlling the state of the airflow around the vehicle body, for example, controlling the operation of a device such as an air spoiler provided in each part of the vehicle body (aerodynamic control) It is a means to generate. The “contact state” is a state of an effective frictional force between the tire and the road surface, more specifically, a friction state between the tire and the road surface, and a contact load state of the wheel. The index values such as are referred to. “Detecting the ground contact state of the control wheel of at least one first control means” means that at least one of the control wheels of the first control means is selected as the wheel to be monitored for the ground contact state. It should be understood that multiple control wheels and / or non-control wheels may also be monitored. The “degree of contribution of the first control means” and the “degree of contribution of the second control means” in the control of the motion state of the vehicle are more specifically based on the motion control given to the vehicle body. It may be the ratio of the action amount or control amount given to the vehicle body by the respective control means or the correction amount of the vehicle body direction in the overall control action.

  In the configuration of the apparatus of the present invention described above, in brief, when vehicle motion control is executed in a vehicle having control means based on underbody control and control means based on aerodynamic control. Depending on the ground contact state of the wheel, the control means selected to be used for executing the motion control or the control means mainly used is changed. As already mentioned, the effectiveness of undercarriage control depends on whether or not a significant frictional force, ie, tire force, can be generated on the wheel, that is, on the “ground contact state”. The effectiveness of aerodynamic control is substantially independent of the “ground state”. Therefore, in the present invention, as described above, the “grounding state” of the wheel, in particular, the “grounding state” of the control wheel for suspension control is monitored. This is because the wheel that is generated in the state where the tire force is controlled in the control is the control wheel for the undercarriage control.) According to the grounding state, the first in the control of the motion state of the vehicle. The degree of contribution of the control means and the degree of contribution of the second control means are changed. More specifically, in the motion control, change or selection of the control means to be mainly used is executed. According to such a configuration, when the effectiveness of the underbody control is high due to the ground contact state, the underbody control is preferentially or mainly used or selected, and the effectiveness of the underbody control may be reduced. It is possible to preferentially or mainly use or select aerodynamic control, and thus to obtain significant vehicle motion control effects in various driving conditions as compared to the prior art. It will be expected.

  In the embodiment, more specifically, it is determined that the detected contact state is in a state where the effective frictional force between the tire and the road surface can sufficiently achieve the suspension control. When the effective friction force between the tire and the road surface is sufficiently large, the underbody control is selected, and the detected ground contact state is the effective friction between the tire and the road surface. When it is determined that the magnitude of the force is not sufficient to achieve suspension control, that is, when the effective frictional force between the tire and the road surface is small, is aerodynamic control selected? A combination of aerodynamic control and underbody control may be selected. As a detection of the ground contact state, as one aspect, referring to the wheel speed of each wheel, a wheel that is idling (a wheel that rotates significantly faster than other wheels during acceleration) or a wheel that is locked (when decelerating) If there is a wheel that rotates significantly slower than other wheels), the ground contact state must be such that the effective frictional force between the tire and the road surface is not sufficient to achieve suspension control. It may be determined. Further, as another aspect, when the deviation between the actual yaw rate of the vehicle body and the target yaw rate is considerably large (when it can be determined that it cannot be corrected by the underbody control), the ground contact state is between the tire and the road surface. It may be determined that the magnitude of the effective frictional force is not in a state where the underbody control can be sufficiently achieved. As yet another aspect, the contact load of each wheel is detected, and from the value of the contact load or a change thereof, the amount of effective frictional force between the tire and the road surface is sufficient to control the undercarriage. It may be determined whether it is in a state that can be achieved. In detecting the grounding state, any one of the above aspects or any combination thereof may be employed. Still further, it should be understood that any of the other aspects of ground state detection described below may be employed and still be within the scope of the present invention.

  Thus, according to the present invention described above, when the effectiveness of the underbody control is reduced based on the ground contact state of the wheel, the ground contact state of the wheel and the road surface can be significantly improved by making aerodynamic control available. Effective motion control can be achieved even when the effective frictional force between the two is not in a state where the underbody control can be sufficiently achieved. Therefore, for example, in yaw rate control to prevent lane departure due to crosswinds and to ensure the stability of lane changes, if the road surface friction coefficient is low, such as snowy roads, rainy weather, dirt, etc. In situations where the effectiveness of undercarriage control is reduced when the tire ground contact load decreases, the aerodynamic control is operated instead of or in addition to the undercarriage control. Achievement of control is expected.

  Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the present invention.

1A and 1B are a schematic plan view and a side view of a vehicle on which a preferred embodiment of a motion control apparatus according to the present invention is mounted, and FIG. 1A is a configuration related to underbody control. (B) shows a configuration related to aerodynamic control. 2A and 2B are diagrams showing an example of the processing configuration of the control contribution degree changing means in the motion control apparatus according to the present invention in the form of a flowchart. FIG. 3 is a flowchart showing an example of a processing configuration for detecting a grounding state by determining whether there is a wheel spin or a lock in the grounding state detecting means in the motion control apparatus according to the present invention. It is. FIG. 4 is a flowchart showing an example of a processing configuration for detecting the grounding state by determining the magnitude of the yaw rate deviation in the grounding state detecting means in the motion control apparatus according to the present invention. . FIG. 5 shows, in the form of a flowchart, an example of a processing configuration for detecting the ground contact state by monitoring the change in the ground load of each wheel in the ground state detection means in the motion control apparatus according to the present invention. FIG. FIG. 6A is a diagram showing an example of a processing configuration in the suspension control in the form of a flowchart, and FIG. 6B is a diagram showing a driving force distribution control in the suspension control. The example of the torque distribution ratio provided with respect to a yaw rate deviation is shown. FIG. 6C is a diagram showing a processing configuration example in the aerodynamic control in the form of a flowchart, and FIG. 6D is an example of the displacement amount of the side spoiler given to the yaw rate deviation. Is shown.

DESCRIPTION OF SYMBOLS 10 ... Vehicle 12FL-12RR ... Wheel 16f, 16s, 16r ... Air spoiler 17 ... Air duct 28 ... Differential gear 30 ... Steering device 40 ... Braking system device 42FL-42RR ... Braking device (wheel cylinder)
44 ... Brake pedal 46 ... Hydraulic circuit 60 ... Electronic control device 62 ... Yaw rate sensor

  The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings. In the figure, the same reference numerals indicate the same parts.

Configuration of Device FIG. 1 (A) a car that preferred embodiment of a vehicle motion control device of the present invention is incorporated is shown schematically. In the figure, the vehicle 10 having the left and right front wheels 12FL and 12FR and the left and right rear wheels 12RL and 12RR is arranged in a normal manner according to the depression of the accelerator pedal by the driver (in the illustrated example, Since it is a rear wheel drive vehicle, a drive system device (only part of which is shown) that generates braking / driving force on the rear wheels, and a steering device 30 for controlling the steering angle of the front wheels (further, steering for the rear wheels) And a braking system device 40 that generates a braking force on each wheel. The drive system device is, in a normal manner, from an engine and / or an electric motor (not shown; it may be a hybrid drive device having both an engine and an electric motor) to a transmission (not shown). The driving torque or the rotational force is transmitted to the rear wheels 12RL and 12RR via the differential gear device 28 and the like. The vehicle to which the vehicle motion control device of the present invention is applied is a vehicle equipped with a differential gear device that can variably control the torque ratio distributed to the left and right wheels as the differential gear device 28. Good. In that case, a control command for the total driving force to be generated in the engine and / or the electric motor is given by the electronic control device 60 described later, and a control command for the torque distribution ratio kr is given to the differential gear device 28. Thus, the driving force is adjusted individually or independently in each driving wheel. Further, the steering device transmits the rotation of the steering wheel 32 operated by the driver to the tie rods 36L and 36R while boosting the rotational force by the booster 34, and steers the front wheels 12FL and 10FR. It may be. The steering device may be of a type in which the steering angle can be variably controlled independently of the rotation of the steering wheel 32 by the electronic control device 60 described later.

  The braking system device 40 includes a wheel cylinder 42i (i = FL, FR, RL) mounted on each wheel by a hydraulic circuit 46 that communicates with a master cylinder 45 that is operated in response to depression of a brake pedal 44 by a driver. , RR, and so on)) is an electronically controlled hydraulic brake device in which the brake pressure in the wheel, that is, the braking force in each wheel is adjusted. In the hydraulic circuit 46, various valves (master cylinder cut valve, hydraulic pressure holding valve) for selectively communicating the wheel cylinder of each wheel to a master cylinder, an oil pump or an oil reservoir (not shown) in a normal manner. In a normal operation, the pressure of the master cylinder 45 is supplied to each wheel cylinder 42i in response to the depression of the brake pedal 44. Further, when adjusting the braking force of each wheel individually or independently in order to execute vehicle motion control or other arbitrary braking force distribution control, the above-described various types of control are performed based on commands from the electronic control unit 60. The brake pressure in the wheel cylinder of each wheel is controlled to match the target pressure based on the detection value of the corresponding pressure sensor. The braking system device 40 may be of a type that applies a braking force to each wheel pneumatically or electromagnetically, or any other type for those skilled in the art.

  Furthermore, in a vehicle to which the vehicle motion control device of the present invention is applied, the airflow around the vehicle body is controlled at any part of the vehicle body as schematically illustrated in FIG. Devices for aerodynamic control such as an air spoiler and an air duct for controlling the aerodynamic force acting on the vehicle body are provided. These aerodynamic devices change the amount of protrusion and / or inclination, the amount of air flow, etc., in order to generate aerodynamic force so that the moment required for control acts on the vehicle body based on the command of the electronic control unit 60. Is done.

  The operation control of each part described above by the motion control device of the present invention is executed by the electronic control device 60 as already mentioned. The electronic control unit 60 may include a microcomputer and a drive circuit having a CPU, a ROM, a RAM, and an input / output port device which are connected to each other by a bidirectional common bus. In the figure, the electronic control unit 60 receives the brake pedal depression amount θb, the steering angle δ, the wheel speed Vwi of each wheel, the pressure Pbi in the wheel cylinder, the ground load Wti from the sensors provided in each part of the vehicle. (I is an index value representing FL (left front wheel), FR (right front wheel), RL (left rear wheel), FR (right rear wheel), and i indicates that all are referenced. )), The detected value such as the yaw rate γa is illustrated as input, but various parameters necessary for various controls to be executed in the vehicle of the present embodiment, such as the front and rear G sensor values, the lateral G Various detection signals such as sensor values may be input.

Control means selection control (configuration of control contribution degree changing means)
In the vehicle exemplified above, as means for controlling the movement of the vehicle, the braking / driving force of each wheel is individually or independently controlled, or the suspension control means for controlling the steering angle of the steered wheels, An aerodynamic control means for controlling an air force acting on the vehicle body by controlling an airflow around the vehicle body. These control means are provided with a control moment for correcting the motion when the motion of the vehicle becomes unstable or when there is a risk, as already described in the section “Summary of the Invention”. Therefore, the braking / driving force or the steering angle of each wheel or the operation of the air spoiler is controlled.

  Of the above-mentioned means for motion control, in particular, in the underbody control means, when the motion state of the vehicle becomes unstable due to the action of a crosswind force (external force) or due to the manner of steering of the vehicle ( For example, in the case of a drift-out state or a spin state, the balance of the tire force of each wheel is adjusted, and the balanced tire force is transmitted to the vehicle body, so that the actual motion state is targeted. A control moment is generated to correct the state. In this regard, as already mentioned, the tire force of each wheel is the frictional force between the tire and the road surface, and this frictional force is the product of the friction coefficient on the tire contact surface and the tire contact load. As described above, there is a limit depending on the friction coefficient and the ground load in the magnitude of the frictional force that can be generated. Therefore, when the friction coefficient or ground contact load is low, for example, when the road surface friction coefficient such as snowy road, rainy weather, dirt, etc. is low, or the lift generated in the vehicle by the air current is large, and the upward force acts on the vehicle body Therefore, when the ground contact load of the tire decreases, the frictional force that can be generated becomes small, and a situation in which the control moment required for correcting the motion cannot be sufficiently achieved may occur. In particular, in such a situation, the road surface immediately after exiting the tunnel is a snowy road or an ice burn, and this causes the frictional force between the tire and the road surface to be small, This can occur if the lift of the vehicle increases when the vehicle is beaten, thereby reducing the ground load. That is, it can be said that the control effect of the underbody control is easily influenced by the ground contact state of the wheels, that is, the magnitude of the friction force or the friction coefficient between the tire and the road surface, and the magnitude of the ground load.

  On the other hand, in the case of aerodynamic control, since the aerodynamic force acting directly on the vehicle body is controlled, the ground contact state of the tire is not substantially affected. Also, aerodynamic control works more effectively when the air flow around the car body is large, but the lift acting on the car body is large, and therefore the car body is lifted in the direction of lifting, reducing the ground contact load of the wheel In many cases, the flow rate of air around the vehicle body is large.

  Therefore, in the present invention, in the ground contact state in which the control effect of the underbody control is reduced, the selection or change of the control means used for the motion control is performed so that the aerodynamic control is preferentially selected or used. Executed.

  Specifically, as one aspect of selection control of the control means, as illustrated in FIG. 2A, the ground contact state of the tire of each wheel is monitored in the manner described later, and the ground contact state is When it is determined that the magnitude of the effective frictional force with the road surface is in a state where the underbody control can be sufficiently achieved (step 10), more specifically, during normal times (between the tire and the road surface) When the effective frictional force is sufficiently large (when the frictional state is not low or the ground contact load is not low), the suspension control is selected as the motion control (step 20). On the other hand, when it is determined that the friction between the tire and the road surface is considerably low, or when the contact load is determined to be considerably low, that is, when the contact state is an effective frictional force between the tire and the road surface. When it is determined that the suspension control is not sufficiently achieved (when it is in a low friction state or a low ground load) (step 10), aerodynamic control is selected as the motion control (step 25). That is, the degree of contribution of underbody control and the degree of contribution of aerodynamic control are changed according to the ground contact state. As another example, as illustrated in FIG. 2B, the ground contact state is not in a state in which the magnitude of the effective frictional force between the tire and the road surface can sufficiently achieve the suspension control. When the determination is made, aerodynamic control may be additionally used to compensate for a reduction in the control effect of the underbody control. Although not shown, the control gain of the control amount given by the underbody control is reduced when the friction is low or the ground contact load is lower than that when the suspension is not low friction or the ground contact load. The degree of contribution of each control may be changed such that the control gain of the control amount given by the control is increased as compared with when the low friction state or the low ground load is not applied. The illustrated processing configuration may be realized by executing a program stored in advance in the electronic control unit 60 of FIG. Further, the process may be repeatedly executed while the vehicle is traveling.

Detection of Ground State Detection or monitoring of the ground state in the processing of step 10 in FIGS.

(1) Judgment based on presence / absence of wheel / spin / lock Whether or not the ground contact state is a state in which the effective frictional force between the tire and the road surface can sufficiently achieve suspension control, that is, the ground contact state Whether the vehicle is in a low friction state or a low ground load state depends on the presence or absence of wheels that are idle (wheel / spin) when the vehicle is accelerating, and the presence or absence of locked wheels when the vehicle is decelerated. Judgment is possible. That is, when there is a wheel that rotates significantly faster than the vehicle speed during acceleration of the vehicle and when a wheel that rotates significantly slower than the vehicle speed exists when the vehicle decelerates, It can be determined that the ground contact load state is present. FIG. 3 shows an example of processing for detecting a grounding state by determination based on the presence / absence of such wheel spin and lock. The illustrated processing configuration may be realized by executing a program stored in advance in the electronic control unit 60 of FIG. Further, the process may be repeatedly executed while the vehicle is traveling.

  Referring to the figure, in the process, first, the wheel speed value Vwi of each wheel is detected from the wheel speed sensor of each wheel (step 30), and then the absolute vehicle speed Vabs of the vehicle is calculated. (Step 32). The absolute vehicle speed Vabs may be calculated by any method. As one aspect, the wheel speed value Vwi may be determined by an arbitrary algorithm, but the wheel speed value of each wheel is used later to determine whether the wheel spins or locks. The ground vehicle speed value obtained without using the speed value is preferable. Then, it is determined whether or not the vehicle is substantially in a straight traveling state by determining whether or not the magnitude of the steering angle is smaller than a threshold value δth that is arbitrarily set (step 34). When the size of the corner is larger than the predetermined value, that is, when it is determined that the vehicle is not turning straight but turning, the determination process ends. This is because, in a later process, it is determined whether or not there is a considerably high value or a low value among the wheel speed values of each wheel. This is because it is difficult to accurately determine the wheel speed value. The threshold value δth is a limit value of the steering angle at which it can be determined that the vehicle is substantially in a straight traveling state, and an experimentally determined value may be set.

  Thus, when the vehicle is substantially in a straight traveling state, it is determined whether or not the wheel speed value Vwi of each wheel is larger than a value obtained by adding the predetermined value Δ1 to the absolute vehicle speed Vabs (step 36). This determination process is a process for determining whether or not there is a wheel spinning wheel when the vehicle is accelerated. When there is a wheel having a wheel speed value greater than Vabs + Δ1, the wheel has a significant frictional force. It is determined that the wheel is spinning and cannot be generated. Here, when it is determined that the wheel speed value is greater than Vabs + Δ1 in at least one wheel, it may be determined that the ground contact state is a low friction state or a low ground load state. The predetermined value Δ1 is a minimum value that can be determined to be in the wheel / spin state when the wheel speed value Vwi exceeds the vehicle speed Vabs by the predetermined value, and an experimentally determined value is set. It's okay.

  On the other hand, when the wheel speed value Vwi of each wheel is lower than Vabs + Δ1, it is determined whether or not the wheel speed value Vwi of each wheel is smaller than a value obtained by subtracting the predetermined value Δ2 from the absolute vehicle speed Vabs (step 38). . This determination is a process for determining whether or not there are wheels that are wheel-locked when the vehicle decelerates. When at least one wheel has a wheel speed value smaller than Vabs-Δ2, The wheel may be determined to be a wheel locked without generating a significant frictional force, and the ground contact state may be determined to be a low friction state or a low ground load state. The predetermined value Δ2 is a minimum value that can be determined to be in the wheel lock state when the wheel speed value Vwi is lower than the vehicle speed Vabs by the predetermined value, and is set to an experimentally determined value. It's okay.

(2) Judgment based on magnitude of yaw rate deviation When the grounding state is a low friction state or a low grounding load state, if the vehicle turns, grip traveling cannot be ensured, and an understeer state or a drift-out state occurs. In particular, when the degree becomes considerably large, it can be determined that the ground contact state is not a state where the magnitude of the effective frictional force between the tire and the road surface can sufficiently achieve the suspension control. Therefore, in another aspect of detecting the ground state, the determination of the ground state is executed with reference to the magnitude of the yaw rate deviation. FIG. 4 shows an example of processing for detecting the ground contact state by determining the magnitude of the yaw rate deviation. The illustrated processing configuration may be realized by executing a program stored in advance in the electronic control unit 60 of FIG. Further, the process may be repeatedly executed while the vehicle is traveling.

  Referring to the figure, in the processing, first, the values of the steering angle δ and the actual yaw rate γa detected by each sensor are read (step 50), and the absolute vehicle speed Vabs is calculated (step 52: step 32). The target yaw rate γt is calculated from these values, and it is determined whether or not the difference between the target yaw rate γt and the actual yaw rate γa is larger than the threshold value Δγth. Is done. Here, the target yaw rate γt is a target value of the yaw rate when the vehicle is turning while ensuring grip traveling, for example, a value calculated using the motion theory of the vehicle during an arbitrary steady turn. It's okay. When the magnitude of the difference between the target yaw rate γt and the actual yaw rate γa is larger than the threshold value Δγth, it may be determined that the ground contact state is a low friction state or a low ground load state. When the difference between the target yaw rate γt and the actual yaw rate γa is larger than the threshold value Δγth, the threshold value Δγth is set to a value that does not sufficiently correct the vehicle body direction in the underbody control, and is determined experimentally. Set values may be set. (When the magnitude of the yaw rate deviation γt−γa is smaller than the threshold value Δγth, the vehicle body movement is corrected by the underbody control described later.)

(3) Judgment based on contact load As already described, when the contact load (vertical load) on the vehicle wheel is small, the frictional force on the contact surface of the tire is reduced. In particular, the reduction of the ground load on the wheels occurs when the vehicle body is lifted when the lift force acting on the vehicle body is increased by the air flow while the vehicle is running. Therefore, in still another aspect of the detection of the ground contact state, the determination of the ground contact state is executed with reference to the reduction amount of the ground load during traveling with respect to the stopped ground load. FIG. 5 shows an example of processing for detecting the ground contact state by determining the contact load reduction amount. The illustrated processing configuration may be realized by executing a program stored in advance in the electronic control unit 60 of FIG. Further, the process may be repeatedly executed while the vehicle is traveling.

  Referring to the figure, in the process, it is first determined whether or not the vehicle is substantially stopped (whether or not vehicle speed V is smaller than a predetermined value ε1) (step 60). Here, it is only necessary that the aerodynamic force of the airflow on the vehicle is substantially the same as that in the stopped state, and the vehicle may be traveling at a very low speed. The vehicle speed V may be a value arbitrarily acquired from a wheel speed value or other information. When vehicle speed V <predetermined value ε1, the contact load value Wtis of each wheel at the time of stop is read from a contact load sensor provided on each wheel (step 62). When V <ε1, the reading of the ground load value Wtis of each wheel at the time of stopping is not executed, and the latest value read in the past may be used in the subsequent processing. Next, in the processing, it is determined whether or not the vehicle is traveling at a constant speed, for example, whether or not the vehicle acceleration dV / dt is greater than a predetermined acceleration threshold value ε2, and the vehicle is not traveling at a constant speed. If, i.e., dV / dt> ε2, the process ends (step 64). This is because when the vehicle is not traveling at a constant speed, that is, when accelerating or decelerating, load movement occurs between wheels in the vehicle, and it is difficult to determine the amount of change from the value at the time of stopping the ground load of each wheel. It is because it becomes.

  Thus, when it is determined that the vehicle is traveling at a constant speed (step 64), the ground load value Wti of each traveling wheel is read from the ground load sensor provided on each wheel (step 66). The amount of change ΔWti is calculated from the value at the time when the ground load of each wheel is stopped (step 68). As already mentioned, since the traveling vehicle receives at least the traveling wind, the vehicle body receives an upward force due to the lift generated therefrom. In this state, if the upward force of the vehicle body is excessive, the amount of change ΔWti is excessive from the value when each wheel is in contact with the ground load. Therefore, when the amount of change ΔWti is larger than the predetermined threshold value ΔWt_th from the value when one of the wheels is in contact with the ground load (step 70), it may be determined that the load is low (step 72). The predetermined threshold value ΔWt_th may be set to an experimentally determined value. Further, in the undercarriage control, it becomes a problem whether or not the tire force is sufficiently exerted on the control wheel. Therefore, the detection and determination of the amount of change in the ground load is performed by at least one undercarriage control. It may only be executed in the control wheel.

(4) Other ground state detection methods In addition to the processes illustrated in FIGS. 3 to 5 above, examples of ground state detection methods include:
a. When road surface freeze is expected from road information and cloud information b. The outside air temperature is low and the wiper is driven c. When the acceleration is ON and the actual acceleration falls below the target acceleration calculated from the engine (motor) estimated torque d. When the actual deceleration does not reach the deceleration expected from the pedaling force when the brake is turned on, a process for determining that the ground contact state is the low friction state or the low ground load state may be executed.

  In step 10 of FIG. 2, the detection method of the grounding state actually employed may be any one of the processes illustrated in FIGS. 3 to 5 or any combination thereof. When using multiple types of grounding state detection methods, if one of them is determined that the grounding state is a low friction state or a low grounding load state, the grounding state is a low friction state. Alternatively, the process may be executed assuming that the ground contact load state is low.

Mode of Motion Control The undercarriage control and aerodynamic control executed as the vehicle motion control in steps 20 and 25 in FIG. 2 may be executed in a manner that can be arbitrarily executed by those skilled in the art.

  For example, in the underbody control, as illustrated in FIG. 6A, the steering angle δ / actual yaw rate γa is detected (step 100), the absolute vehicle speed Vabs is calculated (step 102), and the target yaw rate γt is set. After the calculation (step 104) is executed, based on the yaw rate deviation Δγ = γt−γa (step 106) calculated from these values, a control moment acting in a direction to reduce the yaw rate deviation Δγ is generated. Then, the target value of the distribution of braking / driving force of each wheel and / or the target value of the steering angle is determined (step 108), and the control command value is sent to the actuator of each part so as to realize the target value, respectively (step 108). Step 110). In calculating the braking / driving force distribution target value of each wheel, as shown in FIG. 6B, a dead zone in which the control is not executed may be provided while the yaw rate deviation Δγ is relatively small.

  On the other hand, in the aerodynamic control, as illustrated in FIG. 6C, the yaw rate deviation Δγ is calculated similarly to the underbody control. (Steps 200 to 206) Then, based on the yaw rate deviation Δγ, the air spoiler operation amount is calculated so as to generate an aerodynamic force that generates a control moment that acts in a direction to reduce the yaw rate deviation Δγ. A control command value is sent (step 210). In the calculation of the target value of the air spoiler operation amount, as shown in FIG. 6D, a dead zone in which control is not executed may be provided while the yaw rate deviation Δγ is relatively small.

  Thus, according to the configuration of the present invention described above, the ground contact state of the wheel is effectively changed between the tire and the road surface by selecting or changing the control means mainly used for motion control based on the ground contact state of the wheel. Even when the magnitude of the frictional force is not in a state where the underbody control can be sufficiently achieved, effective motion control can be achieved.

  Although the above description has been made in relation to the embodiment of the present invention, many modifications and changes can be easily made by those skilled in the art, and the present invention is limited to the embodiment exemplified above. It will be apparent that the invention is not limited and applies to various devices without departing from the inventive concept.

Claims (1)

  A vehicle motion control device for controlling a motion state of a vehicle, wherein the motion state is controlled by controlling first and second control means for controlling the motion state by controlling braking / driving force, and aerodynamic force acting on a vehicle body. Second control means for controlling the ground, ground contact state detection means for detecting the ground contact state in the control wheel of the at least one first control means, and the first control means for controlling the motion state And a control contribution degree changing means for changing the degree of contribution of the second control means and the degree of contribution of the second control means based on the detected grounding state.

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