JP2006248413A - Roll characteristic control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make suitable a control amount of a roll characteristic control device for a vehicle when the vehicle is turning on a low friction-coefficient road surface at a low vehicle speed in the roll characteristic control device for the vehicle. <P>SOLUTION: An electronic control unit 34 calculates a presumption lateral acceleration according to a vehicle speed detected by a vehicle speed sensor 31 and a steering angle detected by a steering angle sensor 32. The electronic control unit 34 calculates a twist angle of a torsion bar 21c at traveling on a high friction-coefficient road surface from the detected vehicle speed and a steering angular velocity and calculates a road surface friction reflection lateral acceleration reflecting the friction state of the road surface from a difference amount of the twist angle and a twist angle detected by a twist angle sensor 33. The electronic control unit 34 corrects the presumption lateral acceleration using the road surface friction reflection lateral acceleration when it is determined that the vehicle travels on a predetermined low friction coefficient road surface and controls the driving of an electric motor 15 according to the corrected presumption lateral acceleration. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a roll characteristic control device for a vehicle that controls a roll of a vehicle by controlling an actuator.

Conventionally, as described in, for example, Patent Document 1 below, a stabilizer control device for a vehicle including a hydraulic cylinder device as an actuator and a stabilizer bar having one end connected to a piston rod of the hydraulic cylinder device is provided. Are known. In this stabilizer control device, the estimated lateral acceleration of the vehicle is calculated according to the vehicle speed detected by the vehicle speed detecting means and the steering angle of the steering wheel detected by the steering angle detecting means, and according to the calculated estimated lateral acceleration. The amount of twist of the stabilizer bar is determined, and the roll of the vehicle is suppressed.
Japanese Patent Publication No. 6-84126

  By the way, when the vehicle is turning on a low friction coefficient road surface such as a snowy road or a freezing road, the actual vehicle speed and steering angle are small due to idling of driving wheels, side slipping of the vehicle, and the like. The detected vehicle speed and steering angle are increased. Therefore, in this case, if the estimated lateral acceleration is calculated only according to the detected vehicle speed and the steering angle, and the vehicle roll is suppressed according to the calculated estimated lateral acceleration, the control amount of the stabilizer control device is excessive. There is a risk of becoming.

  For this reason, in the above-described conventional stabilizer control device, the frictional condition of the road surface is estimated based on the ratio of the calculated estimated lateral acceleration to the actual lateral acceleration detected by the lateral acceleration detecting means, and this ratio has a predetermined ratio. When the upper limit is exceeded, the road surface is estimated to have a low friction coefficient, and the estimated lateral acceleration is reduced and corrected so that the control amount of the stabilizer control device does not become excessive.

  However, when the vehicle is turning at a low vehicle speed, the actual lateral acceleration generated in the vehicle is small, so it is difficult to distinguish the actual lateral acceleration detected by the lateral acceleration detecting means from the disturbance. Therefore, since it is difficult to accurately detect the actual lateral acceleration at a low vehicle speed, the ratio falls below a predetermined ratio even when the vehicle is turning on a low friction coefficient road surface. It may be presumed to be a road surface. As a result, in the conventional stabilizer control device described above, the control amount of the stabilizer control device may increase when the vehicle is turning on a low friction coefficient road surface at a low vehicle speed.

  The present invention has been made to cope with the above-described problem, and the object thereof is represented by, for example, a stabilizer control device even when the vehicle is turning on a low friction coefficient road surface at a low vehicle speed. An object of the present invention is to provide a roll characteristic control device for a vehicle that can set the control amount of the roll characteristic control device to an appropriate size.

  In order to achieve the above object, the present invention is characterized in that in a vehicle roll characteristic control device having an actuator for suppressing vehicle roll, vehicle speed detection means for detecting a vehicle speed and steering for detecting a steering angle of a steering wheel. Angle detection means, twist amount detection means for detecting the twist amount of the steering shaft, estimated lateral acceleration calculation means for calculating the estimated lateral acceleration of the vehicle according to the detected vehicle speed and steering angle, and the detected steering The road surface friction reflecting lateral acceleration calculating means for calculating the road surface friction reflecting lateral acceleration of the vehicle reflecting the road surface friction state according to the amount of twist of the shaft, and the calculated using the calculated road surface friction reflecting lateral acceleration. Correction means for correcting the estimated lateral acceleration, and drive control means for driving and controlling the actuator according to the corrected estimated lateral acceleration are provided. In the door. In this case, for example, the steering shaft includes a steering input shaft having an upper end connected to a steering handle and a steering output shaft having a lower end connected to a steering gear, and between the lower end of the steering input shaft and the upper end of the steering output shaft. It is preferable that the torsion bar is provided integrally, and the torsion amount detecting means detects the torsion amount of the torsion bar as the torsion amount of the steering shaft. In addition, for example, a steering angular velocity detection unit that detects a steering angular velocity of the steering wheel is further provided, and the road surface friction reflected lateral acceleration calculation unit is configured so that the vehicle has a predetermined high friction coefficient road surface according to the detected vehicle speed and steering angular velocity. A reference torsion amount calculating means for calculating a reference torsion amount of the torsion bar when traveling is provided, and a road surface friction reflecting lateral acceleration is calculated using the calculated reference torsion amount and the detected torsion amount. There should be. In addition, for example, the correction unit includes a determination unit that determines whether or not the vehicle is traveling on a predetermined low friction coefficient road surface based on the ratio of the calculated road friction reflected lateral acceleration and the estimated lateral acceleration. In addition, when the determination means determines that the vehicle is traveling on a predetermined low friction coefficient road surface, the ratio may be set as a correction coefficient.

  When the vehicle is turning on a low friction coefficient road surface, the frictional force that the wheels receive from the road surface is smaller than when the vehicle is turning on a high friction coefficient road surface. The amount of twisting of the steering shaft becomes smaller with respect to the operation amount. Therefore, if attention is paid to the amount of twisting of the steering shaft, the road surface friction reflecting lateral acceleration reflecting the road surface friction state can be calculated even at a low vehicle speed. By correcting the estimated lateral acceleration using this road friction reflected lateral acceleration, the accuracy of the estimated lateral acceleration can be increased, so even if the vehicle is turning on a road surface with a low friction coefficient at a low vehicle speed. The control amount of the roll characteristic control device can be set to an appropriate size.

  Further, the steering shaft (torsion bar) is twisted in response to the rotation operation of the steering handle. Therefore, by detecting the amount of twisting of the steering shaft (torsion bar), the road surface friction reflecting lateral acceleration can be calculated at an early stage with respect to the lateral acceleration generated in the vehicle, thereby preventing response delay of the roll characteristic control device. Is possible.

  A feature of the invention that makes the present invention more specific is that the correction means determines the newly obtained ratio when the newly obtained ratio becomes smaller than the ratio that is already set as the correction coefficient. The correction coefficient is changed and set, and when the newly obtained ratio becomes larger than the ratio already set as the correction coefficient, the set ratio is maintained and set as the correction coefficient. .

  According to this, since the frequency of changing the correction coefficient is reduced, it is possible to smooth the movement of the vehicle when the roll is suppressed. Further, a predetermined response time is required until the roll suppression control is performed based on the corrected estimated lateral acceleration. For this reason, for example, when a low friction coefficient road surface and a high friction coefficient road surface are repeated, if the correction coefficient is frequently reduced or increased in accordance with the change in the frictional condition of the road surface, the roll characteristic control device There is a case where the control amount does not match the frictional condition of the road surface, and the movement of the vehicle at the time of roll suppression may become unnatural. However, according to this specific invention, since the correction coefficient is not changed one by one in accordance with the change in the frictional condition of the road surface, the unnatural movement of the vehicle at the time of roll suppression is reduced and the movement of the vehicle is stabilized. It is possible to improve the steering stability.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a stabilizer control device as a vehicle roll characteristic control device according to the present invention.

  The stabilizer control device includes stabilizer bars 11 and 12 divided into two. The stabilizer bars 11 and 12 are assembled to the left and right front wheels FW1 and FW2 via the wheel-side members at the respective outer end portions, and rotate about the axis of the vehicle body BD via the bearings 13 and 14 at the respective intermediate portions. It is assembled as possible.

  Between the stabilizers 11 and 12, an electric motor 15 as an actuator and a speed reduction mechanism 16 are interposed. The inner end of the stabilizer bar 11 is connected to the stator of the electric motor 15, and the inner end of the stabilizer bar 12 is connected to the output shaft of the speed reduction mechanism 16. As a result, the electric motor 15 rotates the stabilizer bar 12 relative to the stabilizer bar 11 around the axis line via the speed reduction mechanism 16 by the rotation, thereby suppressing the roll of the vehicle.

  Next, an electric control device that controls the operation of the electric motor 15 will be described. The electric control apparatus includes a vehicle speed sensor 31, a steering angle sensor 32, and a torsion angle sensor 33, and also includes an electric control circuit including an electronic control unit 34 and a drive circuit 35. Here, since the steering angle sensor 32 and the torsion angle sensor 33 are assembled to the steering shaft 21, the steering shaft 21 will be described first.

  The steering shaft 21 includes a steering input shaft 21a connected to the steering handle 22 so as to rotate integrally at the upper end, and a steering output shaft 21b connected to the pinion gear 23 so as to rotate integrally therewith. A torsion bar 21c is interposed integrally between the steering input shaft 21a and the steering output shaft 21b. The torsion bar 21c is twisted with relative rotation between the steering input shaft 21a and the steering output shaft 21b. The pinion gear 23 meshes with rack teeth formed on the rack bar 24 to constitute a steering gear. Left and right front wheels FW1 and FW2 are steerably connected to both ends of the rack bar 24. The left and right front wheels FW1 and FW2 are connected to the rack bar 24 as the steering input shaft 21a, the torsion bar 21c, and the steering output shaft 21b rotate about their axes. It is steered left and right according to the displacement in the axial direction.

  The vehicle speed sensor 31 detects and outputs the vehicle speed V. The steering angle sensor 32 is assembled to the steering input shaft 21 a and detects the steering angle θh of the steering handle 22. The torsion angle sensor 33 includes rotation angle sensors 33a and 33b. The rotation angle sensor 33a is assembled on the outer periphery of the upper portion of the torsion bar 21c, and detects the rotation angle θu of the upper portion of the torsion bar 21c. The rotation angle sensor 33b is assembled on the outer periphery of the lower portion of the torsion bar 21c, and detects the rotation angle θd of the lower portion of the torsion bar 21c. The steering angle θh represents the steering angle when the steering handle 22 is steered in the left direction and the right direction by positive and negative values, respectively. The rotation angles θu and θd represent the left and right rotation angles of the torsion bar 21c. Represent each.

  The electronic control unit 34 is constituted by a microcomputer whose main components are a CPU, a ROM, a RAM, and the like. The electronic control unit 34 repeatedly executes the roll suppression control program of FIG. 2 every predetermined short time, and drives and controls the electric motor 15 via the drive circuit 35. The drive circuit 35 supplies a drive current to the electric motor 15 in accordance with an instruction from the electronic control unit 34.

  Next, the operation of the embodiment configured as described above will be described. The electronic control unit 34 repeatedly executes the roll suppression control program of FIG. 2 every predetermined short time. The roll suppression control program is started in step S10, and is detected by the vehicle speed V detected by the vehicle speed sensor 31 in step S11, the steering angle θh detected by the steering angle sensor 32, and the rotation angle sensors 33a and 33b. The rotation angles θu and θd of the torsion bar 21c are input.

  First, a case where the vehicle is traveling straight ahead will be described. In this case, the steering angle θh input in step S11 is substantially “0”. Therefore, it determines with "Yes" in step S12, and after the process of step S13 mentioned later, execution of this program is once complete | finished in step S40.

Next, the case where the vehicle travels from straight traveling to turning will be described. In this case, it is determined in step S12 that “No”, that is, the steering angle θh is not “0”, and the process proceeds to step S14. In step S14, the estimated lateral acceleration Gye is calculated based on the vehicle speed V and the steering angle θh input in step S11. The estimated lateral acceleration Gye is expressed using, for example, the following formula (1).
Gye = θh · V ² 1 / (Kh · V ² +1) · 1 / L · 1 / Rs (1)
Here, Kh is a variable representing a stability factor that changes according to the vehicle speed V. L is a constant representing the wheel base, and Rs is a constant representing the neutral steer gear ratio. Note that the estimated lateral acceleration Gye indicates that an acceleration in the right direction is generated with respect to the vehicle when positive, and indicates that an acceleration in the left direction with respect to the vehicle is generated when negative.

  After step S14, it is determined in step S15 whether the vehicle speed V is equal to or higher than a predetermined vehicle speed Vo. The predetermined vehicle speed Vo is an upper limit vehicle speed (for example, 50 to 60 km / h) for determining whether or not it is necessary to execute a process after step S21 to be described later in order to estimate the frictional state of the road surface. . In general, when the vehicle is turning on a low friction coefficient road surface, it is extremely rare to turn at a high vehicle speed equal to or higher than the predetermined vehicle speed Vo. For this reason, when the vehicle speed is equal to or higher than the predetermined vehicle speed Vo, it is estimated that the vehicle is traveling on a high friction coefficient road surface, and in this case, the frictional state of the road surface is not estimated. Accordingly, when the vehicle turns at a high vehicle speed equal to or higher than the predetermined vehicle speed Vo, it is determined as “Yes” in step S15, and the processes after step S16 are executed.

  In step S16, the correction coefficient C is set to “1” which is the maximum value. The correction coefficient C is a variable that is multiplied by the estimated lateral acceleration Gye in order to derive the target lateral acceleration Gy *. In step S17, the correction flag CFL is set to “0” as in the process of step S13. The correction flag CFL represents “0” when the vehicle is traveling on a road surface with a high friction coefficient, or when the vehicle is traveling on a road surface with a low friction coefficient, but is in a friction state where no slip occurs, “1” indicates that the vehicle is running on a road surface with a low friction coefficient and is in a frictional state where slipping occurs.

  After the processing in step S17, in step S18, the estimated lateral acceleration Gye is multiplied by the correction coefficient “1”, that is, the estimated lateral acceleration Gye is set as the target lateral acceleration Gy *. Next, in step S19, the target roll angle RA * is calculated with reference to the roll angle table provided in the ROM of the electronic control unit 34. In this roll angle table, as shown in FIG. 3, the target roll angle RA * increases as the target lateral acceleration Gy * increases from “0” to a positive predetermined value, and the target lateral acceleration Gy * increases from “0”. A target roll angle RA * that decreases as the value decreases to a predetermined negative value is stored. The roll direction of the vehicle body BD indicates that the vehicle body BD is rolled to the right by the positive target roll angle RA *, and the vehicle body BD is rolled to the left by the negative target roll angle RA *. Represents.

  After the process of step S19, the electric motor 15 is driven and controlled via the drive circuit 35 so that the rotational torque in the direction of decreasing the target roll angle RA * is generated in step S20. The electric motor 15 applies the rotational torque between the stabilizer bars 11 and 12 via the speed reduction mechanism 16. As a result, the stabilizer bars 11 and 12 suppress the roll of the vehicle accompanying the turning. After the process of step S20, the execution of this program is once ended in step S40.

  Next, a case where the vehicle turns at a low vehicle speed less than the predetermined vehicle speed Vo will be described. In this case, “No” in step S15, that is, it is determined that the vehicle speed V is less than the predetermined vehicle speed Vo, and the processing after step S21 is executed. In step S21, the steering angular velocity θv (= dθh / dt) is calculated by differentiating the steering angle θh.

  After the process of step S21, the torsion bar 21c that changes in accordance with the steering angular velocity θv and the vehicle speed V with reference to the torsion bar torsion angle table provided in the ROM of the electronic control unit 34 in step S22. The torsion angle θ1 is calculated. This torsion bar torsion angle table stores the torsion angle θ1 (reference torsion amount) of the torsion bar 21c when the vehicle turns on a predetermined reference road surface (high friction coefficient road surface). As shown, a plurality of torsion bar torsion angles θ1 that nonlinearly increase (decrease) in accordance with an increase (decrease) in the steering angular velocity θv are stored for each of a plurality of representative vehicle speed values. The torsion bar twist angle θ1 is larger as the vehicle speed V is lower with respect to the same steering angular velocity θv. Instead of using the torsion bar torsion angle table, the torsion bar torsion angle θ1 that changes according to the steering angular velocity θv and the vehicle speed V is defined in advance by a function, and the same function is used. Thus, the torsion bar twist angle θ1 may be calculated.

  After the process of step S22, in step S23, the rotation angle θd of the torsion bar 21c input in step S11 is subtracted from the rotation angle θd, and the torsion bar twist angle θ2 (= θu−θd) actually generated. ). Then, by subtracting the torsion bar twist angle θ2 from the torsion bar twist angle θ1 calculated in step S22, a difference amount Δθ (= θ1−θ2) of the torsion bar twist angle is calculated.

  After the processing in step S23, in step S24, the road surface friction reflecting lateral acceleration table provided in the ROM of the electronic control unit 34 is referred to, and the torsion bar twist angle difference Δθ and the vehicle speed V are changed. The road surface friction reflecting lateral acceleration Gyr is calculated. As shown in FIG. 5, the road surface friction reflecting lateral acceleration table includes a plurality of non-linearly decreasing (increasing) for each of a plurality of representative vehicle speed values according to an increase (decrease) in the difference Δθ of the torsion bar twist angle. The road surface friction reflecting lateral acceleration Gyr is stored. Since the torsion bar torsion angle θ2 decreases as the road surface friction coefficient decreases, the torsion bar torsion angle difference amount Δθ increases as the road surface friction coefficient decreases. Therefore, the road surface friction reflecting lateral acceleration Gyr calculated using the difference amount Δθ of the torsion bar torsion angle is a value reflecting the road surface friction state. The magnitude of the road surface friction reflecting lateral acceleration Gyr is larger as the vehicle speed V is lower than the difference amount Δθ of the same torsion bar twist angle. Instead of using the road surface friction reflecting lateral acceleration table, the road surface friction reflecting lateral acceleration Gyr and the road surface friction reflecting lateral acceleration Gyr that changes in accordance with the vehicle speed V are defined in advance by using a function. Then, the road surface friction reflecting lateral acceleration Gyr may be calculated.

  After the processing of step S24, in step S25, the road surface friction reflected lateral acceleration Gyr is divided by the estimated lateral acceleration Gye, so that the ratio of the road surface friction reflecting lateral acceleration Gyr to the estimated lateral acceleration Gye is calculated as a ratio obtained by executing this program. Is set as the current ratio Cnew (Cnew = Gyr / Gye). Next, in step S26, it is determined whether or not the correction flag CFL is “1”. Since the correction flag CFL is now set to “0”, “No” is determined in step S26, and the process proceeds to step S27.

  In step S27, it is determined whether or not the current ratio Cnew calculated in step S25 is less than a predetermined value Co. The predetermined value Co is a threshold value corresponding to a low friction coefficient road surface that causes the vehicle to slip, and is set to a predetermined size smaller than “1”. Accordingly, when the vehicle is traveling on the road surface with a high coefficient of friction, since the vehicle does not slip, it is determined in step S27 that “No”, that is, the current ratio Cnew is equal to or greater than the predetermined value Co, and after step S16. Execute the process. Thus, as described above, the estimated lateral acceleration Gye is set as the target lateral acceleration Gy *, and the electric motor 15 is driven and controlled according to the target roll angle RA * calculated from the target lateral acceleration Gy *.

  Further, even when the vehicle is traveling on a low friction coefficient road surface, when the vehicle is in a friction state where no slip occurs, “No”, that is, the current ratio Cnew is equal to or greater than the predetermined value Co in step S27. In the same manner as described above, the processing after step S16 is executed.

  On the other hand, when the vehicle is traveling on the low friction coefficient road surface and is in a frictional state where slipping occurs, “Yes” in step S27, that is, the current ratio Cnew is less than the predetermined value Co. The determination and step S28 and subsequent processes are executed. In step S28, the correction flag CFL is set to “1”.

  After step S28, it is determined in step S29 whether or not the current ratio Cnew set in step S25 is less than the previous ratio Cold set when the previous program was executed. The previous ratio Cold is set to “1” by an initial setting process (not shown). Therefore, in this case, it is determined as “No” in step S29, that is, the current ratio Cnew is less than the previous ratio Cold, and the processes after step S30 are executed.

  In step S30, the current ratio Cnew is set as the correction coefficient C. In step S31, the previous ratio Cold is updated to the current ratio Cnew for the next processing in step S29. After step S31, in step S18, the lateral acceleration obtained by multiplying the estimated lateral acceleration Gye by the correction coefficient C, that is, the road surface friction reflected lateral acceleration Gyr is set as the target lateral acceleration Gy *.

  In step S19, the target roll angle RA * is calculated in accordance with the target lateral acceleration Gy * which is smaller than the estimated lateral acceleration Gye. In step S20, the rotation in the direction in which the target roll angle RA * is decreased. The electric motor 15 is driven and controlled via the drive circuit 35 so that torque is generated. As a result, the stabilizer bars 11 and 12 suppress the roll of the vehicle under the frictional condition in which the slip occurs. After the process of step S20, the execution of this program is once ended in step S40.

  If the vehicle continues to turn at a vehicle speed less than the predetermined vehicle speed Vo, the processes of steps S21 to S26 are executed through the processes of steps S10 to S15. In this case, since the correction flag CFL is set to “1”, “Yes” is determined in step S26, and the process of step S27, that is, the determination process of whether or not the current ratio Cnew is less than the predetermined value Co. Without proceeding to step S29. This processing flow is repeatedly executed until the vehicle speed V becomes “0”, the vehicle speed V becomes equal to or higher than the predetermined vehicle speed Vo, or the steering angle θh becomes “0”. If the vehicle speed V is still less than the predetermined vehicle speed Vo after the correction flag CFL is set to “1”, it is estimated that the vehicle is continuously traveling on the low friction coefficient road surface, and the correction coefficient By not changing the value to “1”, the movement of the vehicle at the time of roll suppression is prevented from becoming unnatural.

  If “Yes”, that is, the current ratio Cnew is less than the previous ratio Cold in step S29, the current ratio Cnew is changed and set as the correction coefficient C in step S30. Thereafter, as in the above, steps S31 and S18 are performed. Processes of steps S20 and S40 are executed. On the other hand, if “No” in step S29, that is, if the current ratio Cnew is equal to or greater than the previous ratio Cold, the previous ratio Cold is maintained and set as the correction coefficient C in step S32. Thereafter, similarly to the above, steps S18 to S20 are performed. , 40 is executed.

  As described in the above description of the operation, in the above embodiment, the torsion bar twists when the vehicle is turning at a low vehicle speed less than the predetermined vehicle speed Vo at a low friction coefficient road surface where slipping occurs. A difference amount Δθ of the torsion bar twist angle is calculated from the angles θ1, θ2, and the road surface friction reflecting lateral acceleration Gyr is calculated according to the difference amount Δθ. Then, the estimated lateral acceleration Gye is corrected using the calculated road friction reflected lateral acceleration Gyr, that is, the road friction reflected lateral acceleration Gyr is set as the target lateral acceleration Gy *. Thereby, since the accuracy of the estimated lateral acceleration can be increased, the rotational torque for the electric motor 15 can be set to an appropriate magnitude.

  In the above embodiment, the torsion bar 21 c is twisted in response to the rotation operation of the steering handle 22. Therefore, by detecting the torsion angle θ2 of the torsion bar 21c, the road surface friction reflecting lateral acceleration Gyr can be calculated at an early stage with respect to the lateral acceleration generated in the vehicle, thereby preventing a delay in response of the stabilizer control device. Is possible.

  Moreover, in the said embodiment, since the frequency of change of the correction coefficient C reduces, it is possible to make the motion of the vehicle smooth at the time of roll suppression. When the current ratio Cnew is larger than the previous ratio Cold, the previous ratio Cold is maintained and set as the correction coefficient C. The current ratio Cnew is corrected only when the current ratio Cnew is smaller than the previous ratio Cold. Since it is changed and set as C, the correction coefficient C is not changed one by one in accordance with the change in the frictional condition of the road surface. As a result, unnatural movement of the vehicle at the time of roll suppression can be reduced, and the movement of the vehicle can be stabilized to improve steering stability.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  For example, in the above embodiment, the ratio obtained by dividing the road surface friction reflected lateral acceleration Gyr by the estimated lateral acceleration Gye is set as the current ratio Cnew, and when the current ratio Cnew is less than a predetermined value Co, The ratio Cnew is set as the correction coefficient C. However, the present invention is not limited to this. For example, when the difference value of the lateral acceleration is calculated by subtracting the road surface friction reflecting lateral acceleration Gyr from the estimated lateral acceleration Gye, and the difference value is larger than a threshold corresponding to a predetermined low friction coefficient road surface. Further, the road surface friction reflecting lateral acceleration Gyr may be set as the target lateral acceleration Gy *.

  In the above embodiment, the estimated lateral acceleration Gye is calculated using the vehicle speed V detected by the vehicle speed sensor 31 and the steering angle θh detected by the steering angle sensor 22, but the vehicle speed sensor 21 and the steering angle sensor 22 are calculated. In addition, a lateral acceleration sensor that detects the lateral acceleration of the vehicle is provided, and when the vehicle turns at a vehicle speed of a predetermined speed Vo or higher, the estimated lateral acceleration is calculated using the detected vehicle speed V, steering angle θh, and lateral acceleration. May be calculated, or the estimated lateral acceleration may be calculated using only the detected lateral acceleration.

  In the above embodiment, the present invention has been described for the case where the present invention is applied to a stabilizer control device in which the twist amount of the stabilizer bar is changed by the rotation of the electric motor, but a hydraulic cylinder device is used instead of the electric motor. The present invention can also be applied to a stabilizer control device in which the torsion amount of the stabilizer bar is changed by the displacement of the piston rod constituting the hydraulic cylinder device. Further, the present invention can be applied not only to the stabilizer control device but also to an active suspension control device capable of controlling the attitude of the vehicle.

1 is an overall schematic diagram of a vehicle roll characteristic control device according to an embodiment of the present invention. It is a flowchart of the roll suppression control program performed by the electronic control unit of FIG. It is a graph which shows the change characteristic of the target roll angle with respect to the target lateral acceleration memorize | stored in the roll angle table provided in the said electronic control unit. It is a graph which shows the change characteristic of the torsion bar twist angle with respect to the steering angular velocity memorize | stored in the torsion bar twist angle table provided in the said electronic control unit. It is a graph which shows the change characteristic of the road surface friction reflection lateral acceleration with respect to the difference amount of the torsion bar twist angle memorize | stored in the road surface friction reflection lateral acceleration table provided in the said electronic control unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11, 12 ... Stabilizer bar, 15 ... Electric motor, 16 ... Deceleration mechanism, 21 ... Steering shaft, 21a ... Steering input shaft, 21b ... Steering output shaft, 21c ... Torsion bar, 31 ... Vehicle speed sensor, 32 ... Steering angle sensor, 33 ... Torsion angle sensor, 33a, 33b ... Rotation angle sensor, 34 ... Electronic control unit, 35 ... Drive circuit

Claims (5)

In a vehicle roll characteristic control device including an actuator for suppressing a vehicle roll,
Vehicle speed detection means for detecting the vehicle speed;
Steering angle detection means for detecting the steering angle of the steering wheel;
A twist amount detecting means for detecting a twist amount of the steering shaft;
Estimated lateral acceleration calculating means for calculating an estimated lateral acceleration of the vehicle according to the detected vehicle speed and steering angle;
Road surface friction reflecting lateral acceleration calculating means for calculating the road surface friction reflecting lateral acceleration of the vehicle reflecting the road surface friction state according to the detected twist amount of the steering shaft;
Correction means for correcting the calculated estimated lateral acceleration using the calculated road friction reflected lateral acceleration;
A vehicle roll characteristic control apparatus comprising drive control means for driving and controlling the actuator in accordance with the corrected estimated lateral acceleration. In the roll characteristic control device for a vehicle according to claim 1,
The steering shaft includes a steering input shaft having an upper end connected to a steering handle and a steering output shaft having a lower end connected to a steering gear, and is integrally provided between the lower end of the steering input shaft and the upper end of the steering output shaft. A roll characteristic control device for a vehicle, wherein the torsion amount detecting means detects the torsion amount of the torsion bar as the torsion amount of the steering shaft. The roll characteristic control device for a vehicle according to claim 1 or 2, further comprising steering angular velocity detecting means for detecting a steering angular velocity of the steering handle,
The road surface friction reflecting lateral acceleration calculating means includes reference torsion amount calculating means for calculating a reference torsion amount of the steering shaft when the vehicle travels on a predetermined high friction coefficient road surface according to the detected vehicle speed and steering angular velocity. A roll characteristic control device for a vehicle that includes the calculated reference torsional amount and the detected torsional amount and calculates road surface friction reflected lateral acceleration. The roll characteristic control device for a vehicle according to any one of claims 1 to 3,
The correction means includes determination means for determining whether or not the vehicle is traveling on a predetermined low friction coefficient road surface based on a ratio between the calculated road friction reflected lateral acceleration and an estimated lateral acceleration, and A roll characteristic control device for a vehicle, wherein when the determination means determines that the vehicle is traveling on a predetermined low friction coefficient road surface, the ratio is set as a correction coefficient. In the vehicle roll characteristic control device according to claim 4,
The correction means changes the newly determined ratio as a correction coefficient when the newly determined ratio is smaller than the ratio already set as a correction coefficient, and is newly determined A roll characteristic control device for a vehicle, which maintains and sets the set ratio as a correction coefficient when the ratio becomes larger than a ratio already set as a correction coefficient.

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