JP5962068B2 - Vehicle attitude control device - Google Patents

Description

  The present invention relates to a vehicle attitude control device that controls the attitude of a vehicle using a front wheel control device that controls front wheels and a rear wheel control device that controls rear wheels.

  Generally, the vehicle attitude control device controls the front wheels and the rear wheels based on the reference yaw rate. For example, the target normative yaw rate is calculated based on information such as the vehicle speed and the steering angle, and the front wheels and the rear wheels are controlled based on the deviation between the normative yaw rate and the yaw rate detected by the yaw rate sensor.

  Patent Document 1 discloses an example of a vehicle attitude control device. The vehicle attitude control device includes yaw moment distribution determining means for determining the operation amounts of the rudder angle control mechanism and the torque control mechanism so that the vehicle moves according to the standard yaw rate. This yaw moment distribution determining means determines the yaw moment distribution of the rudder angle control mechanism and the torque control mechanism in accordance with the margin of the tire friction circle of the front and rear wheels, the frequency component of the target value of the yaw moment, and the like.

JP 2008-94214 A

  Generally, the reference yaw rate is set based on a vehicle model in which tire characteristics belong to a linear region, that is, a linear vehicle model, and an output of a yaw rate sensor in a state where the tire travels while gripping a road surface. However, when there is no deviation between the reference yaw rate and the output of the yaw rate sensor, that is, when the tire is gripped, the vehicle attitude control device does not execute vehicle attitude control based on the reference yaw rate. For this reason, when the tire is gripping, the traveling direction of the vehicle cannot be controlled appropriately.

  In addition, in a vehicle attitude control device having a predetermined yaw rate calculation formula premised on a predetermined vehicle specification, vehicle specifications (for example, vehicle weight, suspension characteristics, etc.) corresponding to the number of passengers and the loaded weight are predetermined. When the vehicle specification changes, the reference yaw rate according to the vehicle specification cannot be calculated using the predetermined reference yaw rate calculation formula. For this reason, the traveling direction of the vehicle cannot be appropriately controlled.

  In order to solve the above-described problems, an object of the present invention is to provide a vehicle attitude control device that can appropriately control the traveling direction of a vehicle.

(1) The first means is the invention according to claim 1, that is, the vehicle attitude control device that controls the attitude of the vehicle using the front wheel control device that controls the front wheels and the rear wheel control device that controls the rear wheels. Based on the side slip angle βf on the front wheel axle, the side slip angle βr on the rear wheel axle , and a predetermined target control balance value α , either the front wheel control device or the rear wheel control device is connected to the vehicle. When it is selected as a device for controlling the attitude and “| βf · α | − | βr · (1-α) |> 0” is satisfied, the rear wheel control device is selected and “| βf · α | When − | βr · (1−α) | <0 ”is satisfied, the front wheel control device is selected, and“ α ”is a value of 0 or more and 1 or less .

  The side slip angle βf decreases as the rotation center of the vehicle approaches the front wheel axle. The side slip angle βr decreases as the rotation center of the vehicle approaches the axle of the rear wheel. That is, the side slip angle βf and the side slip angle βr have a correlation with the rotation center of the vehicle. On the other hand, when the traveling direction of the vehicle is controlled by controlling the front wheels or the rear wheels, the traveling direction of the vehicle can be quickly changed by controlling the wheels near the rotation center of the vehicle.

  In the above invention, since either the front wheel control device or the rear wheel control device is selected to control the front wheel or the rear wheel based on the side slip angle βf and the side slip angle βr correlated with the rotation center of the vehicle, The traveling direction can be appropriately controlled.

In addition, according to the above invention, the vehicle attitude control device not only has a simple magnitude relationship between the side slip angle βf and the side slip angle βr, but also includes either the front wheel control device or the rear wheel control device in consideration of the predetermined target control balance value α. Since either one is selected and the front wheel or the rear wheel is controlled, the degree of freedom in controlling the traveling direction of the vehicle can be increased.

Further , according to the above invention, by selecting the front wheel control device or the rear wheel control device according to the magnitude of “βf · α” and the magnitude of “βr · (1-α)”, the vehicle The traveling direction can be appropriately controlled. In addition, by bringing the target control balance value α closer to 1, there is a high possibility that “| βf · α | − | βr · (1−α) |> 0” is satisfied. Emphasis can be placed on attitude control. In addition, since the possibility that “| βf · α | − | βr · (1−α) | <0” is satisfied by bringing the target control balance value α closer to 0, the attitude control of the vehicle by the front wheel control device. Can be emphasized.

( 2 ) The second means is the invention according to claim 2 , that is, in the vehicle attitude control device according to claim 1 , based on the side slip angle βf, the side slip angle βr, and the target control balance value α. The gist is to calculate one of the control amount of the front wheel by the front wheel control device and the control amount of the rear wheel by the rear wheel control device.

( 3 ) The third means is the invention according to claim 3 , that is, the vehicle attitude control device according to claim 1 or 2 , wherein the target control balance value α is changed according to the vehicle speed. .

  According to the above invention, since the target control balance value α changes according to the vehicle speed, the front wheel control device and the rear wheel control device are selectively used according to the vehicle speed, and the side slip angle of the vehicle body can be controlled according to the vehicle speed. .

( 4 ) The fourth means is the invention according to claim 4 , that is, the vehicle attitude control device according to any one of claims 1 to 3 , wherein the side slip angle βf, the side slip angle βr, and the vehicle Based on the yaw rate, at least one of the control amount of the front wheel by the front wheel control device and the control amount of the rear wheel by the rear wheel control device is calculated.

  According to the above invention, the vehicle attitude control device is configured to control the front wheel control amount by the front wheel control device and the rear wheel control amount by the rear wheel control device in consideration of not only the side slip angle βf and the side slip angle βr but also the yaw rate of the vehicle. At least one is calculated. For this reason, it is possible to control not only the angle formed by the traveling direction of the vehicle with respect to the left and right central axis extending in the front-rear direction of the vehicle, that is, not only the posture of the vehicle but also the traveling locus of the vehicle.

  The present invention provides a vehicle attitude control device that can appropriately control the traveling direction of a vehicle.

The block diagram which shows typically the whole structure about the vehicle attitude | position control apparatus of one Embodiment of this invention. The schematic diagram which shows a vehicle typically about the vehicle attitude | position control apparatus of the embodiment. The flowchart which shows the procedure about the vehicle attitude | position control process performed by the vehicle attitude | position control apparatus of the embodiment. The schematic diagram which shows the attitude | position control of a vehicle about the vehicle attitude | position control apparatus of the embodiment. The schematic diagram which shows the attitude | position control of a vehicle about the vehicle attitude | position control apparatus of the embodiment. The schematic diagram which shows the attitude | position control of a vehicle about the vehicle attitude | position control apparatus of other embodiment of this invention. The schematic diagram which shows the attitude | position control of a vehicle about the vehicle attitude | position control apparatus of other embodiment of this invention.

  FIG. 1 shows an overall configuration of a vehicle 1 including a vehicle body 2, wheels 3, and a vehicle attitude control device 4. In addition, the arrow X in a figure shows the front-back direction including a front and back. An arrow Y in the figure indicates the left-right direction including the left side and the right side. The front-rear direction and the left-right direction are linear directions orthogonal to each other. A linear direction perpendicular to the front-rear direction and the left-right direction is defined as the up-down direction including the upper and lower directions. The front-rear direction, the left-right direction, and the up-down direction indicate directions parallel to the coordinate axes in the orthogonal coordinate system fixed to the vehicle 1.

  The front wheels 31 and 32 that are the front wheels 3 rotate using the front axis AF that is the front axle A as the rotation center axis. The left front wheel 31 is located at a left front side portion of the vehicle body 2. The right front wheel 32 is located at the right front side portion of the vehicle body 2.

  The rear wheels 33 and 34 which are the rear wheels 3 rotate with the rear axis AR which is the rear axle A as the rotation center axis. The left rear wheel 33 is located at a left rear portion of the vehicle body 2. The right rear wheel 34 is located at the right rear portion of the vehicle body 2.

  The power steering device 12 connects the front wheels 31 and 32 and the steering handle 11 for controlling the steering angle of the front wheels 31 and 32. The steering angles of the front wheels 31 and 32 change when the steering handle 11 is operated. On the other hand, the steering angle of the rear wheels 33 and 34 does not change.

  The vehicle attitude control device 4 includes a vehicle slip angle estimation device 5, wheel speed sensors 41 to 44, an acceleration sensor 45, a yaw rate sensor 46, a rudder angle sensor 47, a memory 48, a computing device 49, and front wheel control. A device 6 and a rear wheel control device 7 are included.

  The vehicle slip angle estimation device 5 estimates the side slip angle of the vehicle body 2. The side slip angle of the vehicle body 2 is calculated based on, for example, the yaw rate and acceleration of the vehicle 1 and the friction coefficient of the road surface. Note that if the estimation accuracy of the friction coefficient of the road surface is low, the estimation accuracy of the side slip angle is lowered. Therefore, it is preferable that the side slip angle is calculated based on the lateral force acting on the wheel 3 instead of the friction coefficient of the road surface. . A lateral force acting on the wheel 3 is detected by a tire lateral force sensor (not shown).

  The wheel speed sensor 41 detects the rotational speed of the left front wheel 31. The wheel speed sensor 42 detects the rotational speed of the right front wheel 32. The wheel speed sensor 43 detects the rotational speed of the left rear wheel 33. The wheel speed sensor 44 detects the rotational speed of the right rear wheel 34. On the basis of the wheel speed that is the rotational speed of the wheel 3 detected by the wheel speed sensors 41 to 44, the vehicle speed that is the speed of traveling in the traveling direction of the vehicle 1 is calculated.

As the acceleration sensor 45, for example, a triaxial acceleration sensor that detects acceleration in the front-rear direction, the left-right direction, and the up-down direction is provided.
The yaw rate sensor 46 detects a yaw rate that is an angular velocity of rotation of the vehicle 1 with the vertical direction as the rotation center axis.

The steering angle sensor 47 detects the steering angle of the front wheels 31 and 32. The steering angle detected by the steering angle sensor 47 indicates the actual steering angle of the front wheels 31 and 32, and is different from the steering angle of the steering handle 11.
The memory 48 is a nonvolatile information storage device that stores information. The memory 48 is a program executed by the arithmetic unit 49 and information used for the program, such as a distance from the center of gravity of the vehicle 1 to the front axis AF, a distance from the center of gravity of the vehicle 1 to the rear axis AR, and a target control balance value. Is remembered. By rewriting the target control balance value stored in the memory 48, the target control balance value can be reset.

  The arithmetic device 49 is an integrated circuit composed of an ECU (Electronic Control Unit). The arithmetic device 49 executes a vehicle attitude control process based on a program stored in the memory 48. In the vehicle attitude control process, the arithmetic unit 49 calculates the side slip angle of the vehicle body 2 in the front axis AF and the side slip angle of the vehicle body 2 in the rear axis AR, and based on these side slip angles, the front wheel control device 6 and The rear wheel control device 7 is controlled.

  The front wheel control device 6 is an active steering device capable of controlling the steering angles of the front wheels 31 and 32 without being interlocked with the steering angle of the steering handle 11. The front wheel control device 6 incorporates a rudder angle sensor 47.

  The rear wheel control device 7 is a left and right driving force distribution device that controls the distribution ratio of the driving force of the rear wheels 33 and 34. The rear wheel control device 7 controls the ratio of the driving force of the left rear wheel 33 and the driving force of the right rear wheel 34 with respect to the rear wheels 33 and 34 that are driving wheels.

With reference to FIG. 2, definitions of physical quantities and the like used for attitude control of the vehicle 1 will be described.
An alternate long and short dash line C indicates the left and right central axis of the vehicle 1 (hereinafter, “left and right central axis C”). The left-right central axis C extends in parallel to the front-rear direction of the vehicle 1.

A point G indicates the center of gravity (hereinafter, “center of gravity G”) of the vehicle 1 and the vehicle body 2. In the vehicle 1, the center of gravity G is located between the front axis AF and the rear axis AR in the front-rear direction.
A point R indicates a rotation center (hereinafter, “rotation center R”) of the vehicle 1 and the vehicle body 2 with the vertical direction as the rotation center axis.

An arrow γ indicates the rotation direction (turning direction) of the vehicle 1 with the rotation center R as an axis.
The yaw rate of the vehicle 1 detected by the yaw rate sensor 46 is the angular velocity of the vehicle 1 with the arrow γ in the figure as the positive direction. The vehicle speed detected by the wheel speed sensors 41 to 44 is the speed of the vehicle 1 with the front of the vehicle 1 as the positive direction.

  The angle β corresponds to the side slip angle of the vehicle body 2 estimated by the vehicle body slip angle estimation device 5 (hereinafter, “vehicle body slip angle β”). The vehicle body slip angle β is an angle formed by the traveling direction D of the vehicle 1 and the left and right central axis C at an arbitrary point on the left and right central axis C of the vehicle 1.

  The angle βf corresponds to a side slip angle of the vehicle body 2 in the front axis AF (hereinafter, “side slip angle βf”). The side slip angle βf is determined by the direction in which the front side portion of the vehicle 1 indicated by the arrow Df tries to slide on the left and right central axis C and the front axis AF of the vehicle 1 (hereinafter referred to as “front axis sliding direction Df”), The angle formed with the left and right central axis C. When the front-slip direction Df is directed inward of the turning direction (the direction indicated by the arrow γ) with respect to the left-right central axis C, the side-slip angle βf is represented by a positive number. When the front-slip direction Df is directed outward in the turning direction with respect to the left-right center axis C, the side-slip angle βf is expressed by a negative number.

  The angle βr corresponds to a side slip angle of the vehicle body 2 on the rear axis AR (hereinafter referred to as “side slip angle βr”). The side slip angle βr is determined by the direction in which the rear portion of the vehicle 1 indicated by the arrow Dr tries to slide on the left-right central axis C and the rear axis AR of the vehicle 1 (hereinafter referred to as “rear-slip slip direction Dr”), Is the angle between the left and right central axis C. When the rear-slip slip direction Dr is directed outward in the turning direction (the direction opposite to the arrow γ) with respect to the left-right central axis C, the side slip angle βr is represented by a positive number. When the rear axis slip direction Dr is directed inward in the turning direction with respect to the left and right central axis C, the side slip angle βr is represented by a positive number.

  The side slip angle βf increases as the rotation center R moves away from the front axis AF. Further, the side slip angle βr increases as the rotation center R moves away from the rear axis AR. Therefore, when the rotation center R is located between the front axis AF and the rear axis AR, the side slip angle βr decreases as the side slip angle βf increases. On the other hand, the side slip angle βf decreases as the side slip angle βr increases.

  The angle δ is the steering angle of the front wheels 31 and 32 (hereinafter “steering angle δ”). The steering angle δ is an angle formed by a direction parallel to the rotation surface of the front wheels 31 and 32 indicated by a two-dot chain line R1 in the drawing and the front-rear direction. A two-dot chain line R2 indicates a direction parallel to the rotation surface of the rear wheels 33 and 34.

  An arrow Lf indicates a distance from the rotation center R to the front axis AF (hereinafter, “distance Lf”) in the front-rear direction. An arrow Lr indicates a distance from the rotation center R to the rear axis AR (hereinafter, “distance Lr”) in the front-rear direction. When the rotation center R is located between the front axis AF and the rear axis AR in the front-rear direction, the sum of the distance Lf and the distance Lr is equal to the wheel base of the vehicle 1 indicated by the arrow L. That is, when the distance Lf is “Lf”, the distance Lr is “Lr”, and the wheel base of the vehicle 1 is “L”, the equation “Lf + Lr = L” is established. When the rotation center R is located in front of the vehicle 1 with respect to the front axis AF, the distance Lf is represented by a negative number.

  Note that the wheelbase of the vehicle 1 corresponding to the distance from the front axis AF to the rear axis AR in the front-rear direction is the distance from the center of gravity G to the front axis AF (hereinafter, “distance Cf”) indicated by the arrow Cf and the arrow Cr. Is equal to the sum of the distance from the center of gravity G to the rear axis AR (hereinafter, “distance Cr”). Therefore, when the distance from the center of gravity G to the rotation center R indicated by the arrow E in the figure is “X”, the distance Cf is “Cf”, and the distance Cr is “Cr”, the formula “Lf = Cf + X” and The formula “Lr = Cr−X” is established. When the rotation center R is located in front of the vehicle 1 with respect to the center of gravity G, the distance from the center of gravity G to the rotation center R is represented by a negative number.

  Further, when the side slip angle βf is “βf” and the side slip angle βr is “βr”, the equation “Lr · βf + Lf · βr = 0” is established for the rotation center R. Accordingly, by estimating the sideslip angles βf and βr, the distances Lf and Lr can be calculated, that is, the rotation center R can be derived.

With reference to FIG. 3, the “vehicle attitude control process” executed by the vehicle attitude control device 4 will be described. A series of processing shown in FIG. 3 is executed by the arithmetic unit 49 except for step S1.
In step S1, the vehicle slip angle estimation device 5 estimates the side slip angle β. The estimation result of the side slip angle β is input from the vehicle body slip angle estimation device 5 to the calculation device 49.

  In step S <b> 2, the yaw rate of the vehicle 1 is detected using the yaw rate sensor 46. In step S3, the wheel speed of the wheel 3 is detected using the wheel speed sensors 41 to 44, and the vehicle speed is calculated based on the wheel speed. In step S4, the steering angle of the front wheels 31, 32 is detected using the steering angle sensor 47.

  In step S5, the side slip angle β estimated in step S1, the distance Cf from the center of gravity G to the front axis AF stored in advance in the memory 48, the yaw rate of the vehicle 1 detected in step S2, and in step S3 The side slip angle βf is estimated based on the calculated vehicle speed. Specifically, the side slip angle βf is calculated from the following formula (1). In the following formula, the side slip angle βf is “βf”, the side slip angle β is “β”, the distance Cf is “Cf”, the yaw rate of the vehicle 1 is “γ”, and the vehicle speed is “V”. .

The above formula (1) is the same as the formula when the steering angle of the front wheels is set to “0” in the formula representing the side slip angle of the front wheels in a general vehicle model.

  In step S6, the side slip angle β estimated in step S1, the distance Cr from the center of gravity G to the rear axis AR previously stored in the memory 48, the yaw rate of the vehicle 1 detected in step S2, and in step S3 The side slip angle βr is estimated based on the calculated vehicle speed. Specifically, the side slip angle βr is calculated from the following formula (2). In the following formula, the side slip angle βr is “βr” and the distance Cr is “Cr”.

The above mathematical formula (2) is the same as the mathematical formula representing the side slip angle of the rear wheel in a general vehicle model.

  In step S7, based on the target control balance value stored in advance in the memory 48, the side slip angle βf estimated in step S5, and the side slip angle βr estimated in step S6, it is used for attitude control of the vehicle 1. A control device to be determined is determined. Specifically, when the following formula (3) is satisfied, it is determined that the rear wheel control device 7 is used. On the other hand, when the following numerical formula (4) is satisfied, it is determined that the front wheel control device 6 is used. In the following formula, the target control balance value is “α”.

The above formulas (3) and (4) are established based on the magnitude relationship between the absolute value of “βf · α” and the absolute value of “βr · (1-α)”, that is, the magnitude of “βf · α” and “ It depends on the difference Δβ from the magnitude of “βr · (1−α)”. Hereinafter, the difference Δβ represented by the mathematical expression “| α · βf | − | (1-α) · βr |” is referred to as “Δβ”.

  In the above formulas (3) and (4), when “α” is “0.5”, it is determined that the rear wheel control device 7 should be used when the side slip angle βf is larger than the side slip angle βr. When the angle βr is larger than the side slip angle βf, it is determined to use the front wheel control device 6. That is, when “α” is set to “0.5”, it is determined that the rear wheel control device 7 is used when the rotation center R is closer to the rear wheels 33 and 34 than the front wheels 31 and 32. It is determined to use the front wheel control device 6 when the front wheels 31 and 32 are closer to the rear wheels 33 and 34. Therefore, when “α” is “0.5”, the center of rotation between the front wheels 31, 32 and the rear wheels 33, 34, that is, the center of the front axis AF and the rear axis AR, is the rotation center R. The proper use of the front wheel control device 6 and the rear wheel control device 7 is determined in accordance with the position of. By bringing the target control balance value close to “1”, there is a high possibility that the above formula (3) is satisfied. Therefore, the attitude control of the vehicle 1 by the rear wheel control device 7 can be emphasized. Further, since the possibility that the above formula (4) is satisfied is increased by bringing the target control balance value close to “0”, the attitude control of the vehicle 1 by the front wheel control device 6 can be emphasized.

  In step S8, the attitude of the vehicle 1 is controlled based on the target control balance value stored in advance in the memory 48, the side slip angle βf estimated in step S5, and the side slip angle βr estimated in step S6. The control amount for calculating is calculated. Specifically, the control amount is calculated from the following formula (5). In the following formula, the controlled variable is “Cv”.

In the vehicle 1 in which the rotation center R is located between the front axis AF and the rear axis AR in the front-rear direction, “βf” and “βr” have different signs. “Cv” corresponds to the control amount of the front wheels 31 and 32 by the front wheel control device 6 and the control amount of the rear wheels 33 and 34 by the rear wheel control device 7. The control amount of the front wheels 31 and 32 corresponds to the amount of change in the steering angle of the front wheels 31 and 32. The control amount of the rear wheels 33 and 34 corresponds to the difference between the driving force of the left rear wheel 33 and the driving force of the right rear wheel 34.

  When the lateral slip angle βf is expressed as a positive number when the rear-slip slip direction Dr is directed outward in the turning direction with respect to the left / right central axis C, the formula (5) is replaced with “ The control amount is calculated from “Cv = {α · βf} − {(1−α) · βr}”.

  In step S9, by using one of the front wheel control device 6 and the rear wheel control device 7 determined in step S7 based on the control amount calculated in step S8, the front wheels 31, 32 and the rear wheels 33, 34 are used. Is controlled to control the attitude of the vehicle 1. That is, when it is determined in step S7 that the front wheel control device 6 is to be used, in step S9, the computing device 49 outputs the control amount calculated in step S8 to the front wheel control device 6 as a control signal. On the other hand, when it is determined in step S7 that the rear wheel control device 7 is to be used, in step S9, the calculation device 49 outputs the control amount calculated in step S8 to the rear wheel control device 7 as a control signal. To do.

  In step S9, the front wheel control device 6 to which the control signal is input from the arithmetic unit 49 has “{α · βf} + {(1−α) · βr}” based on the control amount calculated in step S8. The steering angles of the front wheels 31 and 32 are controlled so as to approach “0”. At this time, the amount of change in the steering angle of the front wheels 31 and 32 is increased as the control amount calculated in step 8 is larger.

  Further, in step S9, the rear wheel control device 7 to which the control signal is input from the arithmetic unit 49, “{α · βf} + {(1−α) · βr based on the control amount calculated in step S8. } "Is controlled so that the distribution ratio of the driving force of the rear wheels 33 and 34 approaches" 0 ". At this time, the difference between the driving force of the left rear wheel 33 and the driving force of the right rear wheel 34 increases as the control amount calculated in step 8 increases.

  As described above, the vehicle attitude control device 4 selectively uses the front wheel control device 6 and the rear wheel control device 7 based on the side slip angle βf in the front axis AF and the side slip angle βr in the rear axis AR. The attitude of the vehicle 1 is controlled.

  With reference to FIG. 4, the attitude control of the vehicle 1 when “α = 0.5” and “Δβ> 0” will be described. At this time, the rear wheels 33 and 34 are controlled by the rear wheel control device 7, and the front wheels 31 and 32 are not controlled by the front wheel control device 6. In FIG. 4, it is assumed that the vehicle 1 is rotating in the direction of the arrow γ.

  When “α = 0.5” and “Δβ> 0”, the vehicle 1 is in a head-out posture in which the traveling direction D is located on the rotational direction side of the vehicle 1 with respect to the left-right central axis C. When the posture of the vehicle 1 is a head-out posture, the traveling direction D of the vehicle 1 is a direction in which the front of the vehicle 1 is rotated in the range of more than 0 degrees and less than 90 degrees in the rotation direction (turning direction) of the vehicle 1. . At this time, the rotation center R of the vehicle 1 is located between the front axis AF and the rear axis AR in the longitudinal direction of the vehicle 1. When the vehicle 1 is in the head-out posture, in order to make the traveling direction D of the vehicle 1 coincide with the left-right central axis C, the front side portion of the vehicle 1 is moved in the direction of the arrow γ so that the rotation center R moves forward. Further rotation may be performed.

  Here, when “α = 0.5” and “Δβ> 0”, the rotation center R of the vehicle 1 is greater than that of “α = 0.5” and “Δβ <0”. It can be determined that the side slip angle βf is larger than the side slip angle βr. Therefore, by controlling the rear wheels 33 and 34 provided on the rear shaft AR where the small side slip angle βr is generated, the front wheels 31 and 32 provided on the front shaft AF where the large side slip angle βf is generated are controlled. Compared with the case of controlling, the front part of the vehicle 1 can be quickly rotated.

  When “α = 0.5”, bringing “{α · βf} + {(1−α) · βr}” closer to “0” means that the center of rotation R of the vehicle 1 in the front-rear direction is This means that the vehicle is moved to the center of the rear axis AR, that is, the side slip angle β of the vehicle body 2 at the center of the front axis AF and the rear axis AR in the front-rear direction is brought close to “0”. Therefore, the rear wheel control device 7 increases the driving force of the right rear wheel 34 compared with the driving force of the left rear wheel 33 as shown by the two-dot chain arrow in FIG. Is closer to “0”.

  With reference to FIG. 5, the attitude control of the vehicle 1 when “α = 0.5” and “Δβ <0” will be described. At this time, the front wheels 31, 32 are controlled by the front wheel control device 6, and the rear wheels 33, 34 are not controlled by the rear wheel control device 7. In FIG. 5, it is assumed that the vehicle 1 is rotating in the direction of the arrow γ.

  When “α = 0.5” and “Δβ <0”, the vehicle 1 is in a head-out posture in which the rotation center R of the vehicle 1 is positioned from the front wheels 31 and 32, or as shown in FIG. This is a head-in posture state in which the traveling direction D of the vehicle 1 is located on the opposite side of the rotation direction of the vehicle 1 with respect to the left-right central axis C. When the posture of the vehicle 1 is the head-in posture, the traveling direction D of the vehicle 1 is rotated in the range of more than 0 degrees and less than 90 degrees to the opposite side of the rotation direction (turning direction) of the vehicle 1. Direction. At this time, the rotation center R of the vehicle 1 is located in front of the front axis AF in the longitudinal direction of the vehicle 1. When the vehicle 1 is in the head-in posture, in order to make the traveling direction D of the vehicle 1 coincide with the left-right central axis C, the front side portion of the vehicle 1 is opposite to the arrow γ so that the rotation center R moves backward. Rotate in the direction.

  Here, when “α = 0.5” and “Δβ <0”, the rotation center R of the vehicle 1 is greater than that when “α = 0.5” and “Δβ> 0”. It exists on the front side, and it can be determined that the side slip angle βr is larger than the side slip angle βf. Therefore, by controlling the front wheels 31, 32 provided on the front shaft AF where the small side slip angle βf is generated, the rear wheels 33, 34 provided on the rear shaft AR where the large side slip angle βr is generated are controlled. Compared with the case of controlling, the front part of the vehicle 1 can be quickly rotated.

  When “α = 0.5”, bringing “{α · βf} + {(1−α) · βr}” closer to “0” means that the vehicle body at the center of the front axis AF and the rear axis AR in the front-rear direction. This means that the side slip angle β of 2 approaches “0”. Therefore, the front wheel control device 6 rotates the rotation surfaces of the front wheels 31 and 32 in the direction opposite to the rotation direction of the vehicle 1 as indicated by the two-dot chain arrows in FIG. The angle is brought close to “0”.

  As described above, when “α = 0.5”, the attitude of the vehicle 1 is such that the rotation center R moves to a position where the distance from the front axis AF to the rear axis AR is divided by “5: 5”. Is controlled. When “α = 0.3”, the attitude of the vehicle 1 is controlled so that the rotation center R moves to a position where the distance from the front axis AF to the rear axis AR is divided by “7: 3”. The That is, the attitude of the vehicle 1 is controlled such that the rotation center R moves to a position where the distance from the front axis AF to the rear axis AR is divided by “(1-α): α”.

The operation of the vehicle attitude control device 4 will be described.
Based on the side slip angle βf, the side slip angle βr, and a predetermined target control balance value, a control device used for attitude control of the vehicle 1 is determined among the front wheel control device 6 and the rear wheel control device 7, and the vehicle 1 A control amount for controlling the attitude is calculated. That is, the vehicle posture control device 4 that controls the posture of the vehicle 1 using the front wheel control device 6 and the rear wheel control device 7 is based on the side slip angle βf and the side slip angle βr. Use properly. When “Δβ> 0”, the rear wheel control device 7 controls the rear wheels 33 and 34 so that “{α · βf} + {(1−α) · βr}” approaches “0”. . Further, when “Δβ <0”, the front wheels 31 and 32 are controlled by the front wheel control device 6 so that “{α · βf} + {(1−α) · βr}” is brought close to “0”. Thus, the front wheel control device 6 and the rear wheel control device 7 are selectively controlled according to the sign of “Δβ”.

(Effect of embodiment)
The vehicle attitude control device 4 of the present embodiment has the following effects.
(1) The vehicle attitude control device 4 controls the attitude of the vehicle 1 by controlling one of the front wheel control device 6 and the rear wheel control device 7 based on the side slip angle βf in the front axis AF and the side slip angle βr in the rear axis AR. Select as a device to do. Therefore, the front wheel control device 6 and the rear wheel control device 7 can be coordinated to effectively control the angle formed by the traveling direction D of the vehicle 1 with respect to the left and right central axis C extending in the front-rear direction of the vehicle 1, The traveling direction D of the vehicle 1 can be appropriately controlled.

  (2) The vehicle attitude control device 4 is either one of the front wheel control device 6 and the rear wheel control device 7 based on the side slip angle βf, the side slip angle βr, and a predetermined target control balance value stored in the memory 48. Is selected as a device for controlling the attitude of the vehicle 1. Therefore, the vehicle attitude control device 4 controls either the front wheels 31 and 32 or the rear wheels 33 and 34 by selecting one of the front wheel control device 6 and the rear wheel control device 7 in consideration of a predetermined target control balance value. Therefore, the freedom degree of control of the advancing direction of the vehicle 1 can be raised.

  (3) The vehicle attitude control device 4 selects the rear wheel control device 7 when the mathematical formula (3) is satisfied, and selects the front wheel control device 6 when the mathematical formula (4) is satisfied. Therefore, by selecting the front wheel control device 6 or the rear wheel control device 7 according to the size of “βf · α” and the size of “βr · (1-α)”, the left and right center of the vehicle 1 is selected. The angle formed by the traveling direction D of the vehicle 1 with respect to the axis C can be effectively controlled, and the traveling direction D of the vehicle 1 can be appropriately controlled. Further, by bringing “α” indicating the target control balance value close to 1, the possibility that the above formula (3) is satisfied is increased, and therefore it is possible to place importance on the attitude control of the vehicle 1 by the rear wheel control device 7. . Further, since “α” indicating the target control balance value is brought close to 0, the possibility that the above formula (4) is satisfied is increased. Therefore, it is possible to attach importance to the attitude control of the vehicle 1 by the front wheel control device 6.

  (4) The vehicle attitude control device 4 controls the control amount of the front wheels 31, 32 by the front wheel control device 6 and the rear wheels 33 by the rear wheel control device 7 based on the side slip angle βf, the side slip angle βr, and the target control balance value. 34 is calculated. Therefore, it is possible to determine the control amount of the front wheels 31 and 32 and the control amount of the rear wheels 33 and 34 by the rear wheel control device 7 without being based on the reference yaw rate.

(Other embodiments)
The present invention includes embodiments other than the above-described embodiments. Hereinafter, modifications of the above-described embodiments as other embodiments of the present invention will be described. The following modifications can be combined with each other.

  The vehicle attitude control device 4 of the above-described embodiment (FIG. 1) determines to use the rear wheel control device 7 when the mathematical formula (3) is satisfied. On the other hand, the vehicle attitude control device 4 of the modified example determines to use the rear wheel control device 7 when the following equation (6) is satisfied instead of the above equation (3).

-The vehicle posture control apparatus 4 of the said embodiment (FIG. 1) determines using the front wheel control apparatus 6, when satisfy | filling the said Numerical formula (4). On the other hand, the vehicle attitude control device 4 of the modified example determines to use the front wheel control device 6 when the following equation (7) is satisfied instead of the above equation (4).

In other words, the vehicle attitude control device 4 of the above embodiment controls either the front wheel control device 6 or the rear wheel control device 7 based on the side slip angle βf, the side slip angle βr, and a predetermined control balance. Select as device to control. On the other hand, the vehicle posture control device 4 of the modification example selects either the front wheel control device 6 or the rear wheel control device 7 as a device for controlling the posture of the vehicle based only on the side slip angle βf and the side slip angle βr. To do.

  In the vehicle attitude control device 4 of the above embodiment (FIG. 1), “α” indicating the target control balance value is a value of 0 or more and 1 or less (for example, 0.5) stored in the memory 48. On the other hand, the vehicle attitude control device 4 of the modified example changes the target control balance value according to the vehicle speed. According to such a configuration, since the target control balance value changes according to the vehicle speed, the front wheel control device 6 and the rear wheel control device 7 are selectively used according to the vehicle speed, and the side slip angle of the vehicle body 2 is controlled according to the vehicle speed. can do.

  “Α” corresponding to the vehicle speed is preferably calculated from the following mathematical formula (8). In the following formula, the wheel base of the vehicle 1, that is, the distance from the front axis AF to the rear axis AR in the front-rear direction is “L”, and the target side slip angle β of the vehicle body 2 is “β *”.

The arithmetic unit 49 of the present modification includes the distance Cr from the center of gravity G to the rear axle AR, the target side slip angle β, the wheel base of the vehicle 1 and the yaw rate of the vehicle 1 detected in step S2. Based on the vehicle speed calculated in step S3, the target control balance value is calculated from the above equation (8). In step S7, the attitude control of the vehicle 1 is performed based on the target control balance value calculated by the above equation (8), the side slip angle βf estimated in step S5, and the side slip angle βr estimated in step S6. The control device to be used for the determination is determined. In step S8, the attitude of the vehicle 1 is determined based on the target control balance value calculated by the above equation (8), the side slip angle βf estimated in step S5, and the side slip angle βr estimated in step S6. A control amount that is the degree of control is calculated.

  In the above formula (8), “α” increases as “γ” increases. For this reason, the higher the yaw rate of the vehicle 1, the higher the possibility that the target control balance value approaches “1” and the above formula (3) is established. Therefore, the posture control of the vehicle 1 by the rear wheel control device 7 is performed. Can be emphasized.

  The vehicle attitude control device 4 of the above-described embodiment (FIG. 1) is based on the side slip angle βf, the side slip angle βr, and a predetermined target control balance value, and the control amounts and rear wheels of the front wheels 31, 32 by the front wheel control device 6. The control amount of the rear wheels 33 and 34 by the control device 7 is calculated. On the other hand, the vehicle attitude control device 4 of the modified example is based on the side slip angle βf, the side slip angle βr, and the yaw rate of the vehicle 1, and the control amount of the front wheels 31, 32 by the front wheel control device 6 and the rear wheel by the rear wheel control device 7. The control amounts 33 and 34 are calculated. According to such a configuration, the vehicle attitude control device 4 controls not only the magnitude relationship between the side slip angle βf and the side slip angle βr but also the control amount of the front wheels 31 and 32 and the rear wheels 33, taking into account the yaw rate of the vehicle 1. 34 is calculated. For this reason, not only the angle formed by the traveling direction of the vehicle 1 with respect to the central axis C extending in the front-rear direction of the vehicle 1, that is, the posture of the vehicle 1, but also the travel locus of the vehicle 1 can be controlled.

  The control amount based on the side slip angle βf, the side slip angle βr, and the yaw rate of the vehicle 1 is preferably calculated from the following formula (9). In the following formula, the reference yaw rate calculated from the turning angle of the front wheels 31 and 32 and the vehicle speed is “γ *”. The normative yaw rate has a positive direction in the direction of rotation of the vehicle 1 (the direction indicated by the arrow γ in the figure), similarly to the yaw rate of the vehicle 1 detected by the yaw rate sensor 46.

The computing device 49 of the present modification uses the reference yaw rate based on the turning angle of the front wheels 31 and 32 detected using the steering angle sensor 47 and the vehicle speed detected using the wheel speed sensors 41 to 44. calculate. The arithmetic unit 49 then stores the target control balance value stored in advance in the memory 48, the side slip angle βf estimated in step S5, the side slip angle βr estimated in step S6, the calculated standard yaw rate, and the yaw rate. Based on the yaw rate detected using the sensor 46, a control amount that is a degree of controlling the attitude of the vehicle 1 is calculated. In step S9, the arithmetic unit 49 determines whether the front wheel 31, 32 or the rear wheel so that “{α · βf} + {(1−α) · βr} + (γ * −γ)” approaches “0”. 33 and 34 are controlled.

  In the above formula (9), when “γ * <γ”, as the deviation of the yaw rate from the reference yaw rate increases, “γ * −γ” becomes a negative number having a large absolute value, and thus “Cv” decreases. Become. Further, when “γ *> γ”, as the deviation of the yaw rate from the reference yaw rate increases, “γ * −γ” becomes a positive number having a large absolute value, and thus “Cv” increases. Further, when “γ * = γ”, that is, when it is determined that there is no deviation of the turning trajectory of the vehicle 1, “Cv” in Equation (9) is the control amount calculated from Equation (5) above. The same.

  In the vehicle attitude control device 4 of the above embodiment (FIG. 1), the rear wheel control device 7 is a left / right driving force distribution device. On the other hand, in the vehicle attitude control device 4 of the modified example, the rear wheel control device 7 is an independent drive device. In the modified vehicle attitude control device 4, the rear wheel control device 7 is a rear wheel steering device that can control the steering angle of the rear wheels 33 and 34. In this case, the amount of change in the steering angle of the rear wheels 33 and 34 is increased in step S9 as the control amount calculated in step 8 is larger. That is, the control amount of the rear wheels 33 and 34 by the rear wheel control device 7 corresponds to the amount of change in the steering angle of the rear wheels 33 and 34.

  With reference to FIG. 6, the attitude control of the vehicle 1 when the rear wheel control device 7 is constituted by a rear wheel steering device and “α = 0.5” and “Δβ> 0” will be described. At this time, the rear wheels 33 and 34 are controlled by the rear wheel control device 7, and the front wheels 31 and 32 are not controlled by the front wheel control device 6. In FIG. 6, it is assumed that the vehicle 1 is rotating in the direction of the arrow γ.

  FIG. 6 shows the case where the vehicle 1 is in the head-out posture as in FIG. In the state shown in FIG. 6, the rear wheel control device 7 rotates the rotation surfaces of the rear wheels 33 and 34 in the direction opposite to the rotation direction of the vehicle 1 as indicated by the two-dot chain line arrows in FIG. 6. As a result, the side slip angle β is brought close to “0”.

  As described above, even if the rear wheel control device 7 is configured by the rear wheel steering device, the effect according to the above embodiment can be obtained. That is, the rear wheel control device 7 is not limited to the driving force distribution device that controls the ratio of the driving force of the rear wheels 33 and 34.

  In the vehicle attitude control device 4 of the above embodiment (FIG. 1), the front wheel control device 6 is an active steering device. On the other hand, in the vehicle attitude control device 4 of the modified example, the front wheel control device 6 is an independent drive device or a left / right drive force distribution device. In addition, it is necessary to be comprised so that the rudder angle of the front wheels 31 and 32 can be changed. When the front wheel control device 6 is a left / right driving force distribution device, the difference between the driving force of the left front wheel 31 and the driving force of the right front wheel 32 is increased in step S9 as the control amount calculated in step 8 is larger. That is, the control amount of the front wheels 31 and 32 by the front wheel control device 6 corresponds to the difference between the driving force of the left front wheel 31 and the driving force of the right front wheel 32 for the front wheels 31 and 32 that are driving wheels.

  With reference to FIG. 7, the attitude control of the vehicle 1 when the front wheel control device 6 is configured by a left and right driving force distribution device and “α = 0.5” and “Δβ <0” will be described. At this time, the front wheels 31, 32 are controlled by the front wheel control device 6, and the rear wheels 33, 34 are not controlled by the rear wheel control device 7. In FIG. 7, it is assumed that the vehicle 1 is rotating in the direction of the arrow γ.

  FIG. 7 shows the time when the vehicle 1 is in the head-in posture, as in FIG. In the state shown in FIG. 7, the front wheel control device 6 makes a side slip by increasing the driving force of the left front wheel 31 compared to the driving force of the right front wheel 32 as indicated by the two-dot chain line arrow in FIG. 7. The angle β is brought close to “0”.

  As described above, even if the front wheel control device 6 is configured by the left and right driving force distribution device, the effect according to the above embodiment can be obtained. That is, the front wheel control device 6 is not limited to an active steering device such as a differential mechanism device or a steer-by-wire device that controls the steering angle of the front wheels 31 and 32.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Vehicle body, 3 ... Wheel, 4 ... Vehicle attitude control device, 5 ... Vehicle slip angle estimation device, 6 ... Front wheel control device, 7 ... Rear wheel control device, 11 ... Steering handle, 12 ... Power steering device 31 ... Left front wheel (front wheel), 32 ... Right front wheel (front wheel), 33 ... Left rear wheel (rear wheel), 34 ... Right rear wheel (rear wheel), 41-44 ... Wheel speed sensor, 45 ... Acceleration sensor, 46: Yaw rate sensor, 47: Rudder angle sensor, 48 ... Memory, 49 ... Arithmetic unit, A ... Axle, AF ... Front axle (front axle), AR ... Rear axle (rear axle).

Claims (4)

In a vehicle attitude control device that controls the attitude of a vehicle using a front wheel control device that controls front wheels and a rear wheel control device that controls rear wheels,
Based on the side slip angle βf on the front wheel axle, the side slip angle βr on the rear wheel axle , and a predetermined target control balance value α , either the front wheel control device or the rear wheel control device is connected to the vehicle. Select as a device to control the attitude ,
When “| βf · α | − | βr · (1-α) |> 0” is satisfied, the rear wheel control device is selected,
When “| βf · α | − | βr · (1-α) | <0” is satisfied, the front wheel control device is selected,
“Α” is a value of 0 or more and 1 or less . The vehicle attitude control device according to claim 1 ,
Based on the side slip angle βf, the side slip angle βr, and the target control balance value α, one of the front wheel control amount by the front wheel control device and the rear wheel control amount by the rear wheel control device is calculated. A vehicle attitude control device. The vehicle attitude control device according to claim 1 or 2 ,
The target attitude balance value α is changed according to the vehicle speed. In the vehicle attitude control device according to any one of claims 1 to 3 ,
Calculating at least one of a control amount of the front wheel by the front wheel control device and a control amount of the rear wheel by the rear wheel control device based on the side slip angle βf, the side slip angle βr, and the yaw rate of the vehicle. A vehicle attitude control device.