Vehicle motion control system

Abstract

To enable an automobile to stably travel even if idling by suppressing an unintended vehicle turning motion at the time of slipping or at the time of gripping thereafter.SOLUTION: A control device 10 controls an automobile 11 having a driving source 15, an open diff 16 for transmitting driving force of the driving source 15 to both right and left front wheels 12a and 12b, motor 13a and 13b for driving right and left rear wheels 17a and 17b, respectively, and a detection part 18 for detecting slip of at least one front wheel 12a. A slip state control that controls the motor 17a or 17b that drives the right rear wheel 12a or the left rear wheel 12b or both of them so as to cancel an inertia force generated by a slip of the right front wheel 13a or the left front wheel 13b when the slip of the right front wheel 12a or the left front wheel 12b is detected, and a grip state control that controls the motor 13b or that drives the left rear wheel or the right rear wheel or both of them so as to cancel a driving force when the right front wheel or the left front wheel grips after the slip; 13a 17a 17b, the control device 10 performs at least one of the following controls.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control for stabilizing the behavior of an automobile. [Background technology]

[0002] In most automobiles that are powered solely by an engine, the engine is located in one place and drives either the front or rear wheels. In contrast, in electric automobiles, the electric motors that drive the wheels are smaller than the engine, and separate electric motors can be provided to drive the front and rear wheels. Furthermore, a system in which an electric motor is provided independently for each wheel (in-wheel motor system) has also been proposed (see, for example, Patent Document 1).

[0003] By combining these types of systems, an automobile 11 can be produced that is driven by the system shown in the conceptual diagram of Figure 1. The front wheels 12 (right front wheel 12a, left front wheel 12b) are driven by rotation from a single drive source (e.g., an internal combustion engine or motor) 15, which is transmitted via a right front axle 14a, a left front axle 14b, and an open differential 16. The rear wheels 13 (right rear wheel 13a, left rear wheel 13b) are driven by respective motors (right motor 17a, left motor 17b). Conversely, there is also a system in which an open differential is provided on the rear wheel side and the left and right front wheels are driven by separate motors.

[0004] During normal driving, the open differential 16 outputs the same torque to both the left and right front wheels 12 (12a, 12b). In this case, the driving force generated on the right front wheel 12a is the same as the driving force generated on the left front wheel 12b. When accelerating or decelerating, not only the driving force but also the inertial force must be taken into consideration. However, if the wheels are not spinning while traveling straight, the sum of the driving force and the inertial force is the same on the left and right.

[0005] Let us now consider a situation in which the right front wheel 12a becomes stuck in a swamp or a hole, causing only the right front wheel 12a to spin (slip). The rotation speed of the right front wheel 12a increases rapidly, increasing the inertial force as well as the driving force. Because the open differential 16 outputs the same torque to the left and right wheels, the increase in the inertial force of the right front wheel 12a generates a driving force on the left front wheel 12b. As a result, the driving force of the left front wheel 12b becomes greater than the driving force of the right front wheel 12a.

[0006] Furthermore, when the right front wheel 12a subsequently stops spinning and grips the road surface (grip), the rotation speed remains at a rapid increase corresponding to the amount of spinning. At this time, the driving force of the right front wheel 12a becomes greater than the driving force of the left front wheel 12b, and the relationship becomes (driving force of the left front wheel 12b)<(driving force of the right front wheel 12a). This is because inertial force is added to the torque output via the open differential 16. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2013 / 125031 Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, if there is a difference in the driving force between the left and right front wheels, the automobile 11 will yaw in both cases of slip and grip. When the right front wheel 12a spins during slip, its driving force becomes zero and its rotation speed increases, and the driving force of each wheel becomes as shown by the arrows in Figure 2. The driving forces of the left and right rear wheels are equal. Meanwhile, the driving force of the right front wheel 12a becomes zero, and only the left front wheel 12b generates a driving force equivalent to the inertial force of that wheel. This causes the automobile 11 to turn right due to the driving force of the left front wheel 12b.

[0009] Next, during grip, i.e., when the right front wheel 12a stops spinning, the driving forces on the left and right rear wheels remain equal. Meanwhile, the open differential 16 applies a driving force equal to that of the left front wheel 12b to the right front wheel 12a. Furthermore, as shown in FIG. 6, the combined force of the motor torque and inertia force on the right front wheel 12a is greater than that on the left front wheel 12b. This is because the right front wheel 12a is subjected to an inertia force equal to that of the wheel that was spinning. This causes the automobile 11 to turn left by the difference in driving forces.

[0010] Therefore, an object of the present invention is to suppress unintended vehicle turning movements during such slippage and subsequent gripping, thereby enabling stable running even when the wheels spin. [Means for solving the problem]

[0011] This invention is a drive source; and an open differential that transmits drive force from the drive source to both left and right front wheels; A motor that drives each of the left and right rear wheels; A control device for controlling a vehicle having a detection unit that detects slippage of at least one of the front wheels, If slippage is detected in the right or left front wheel, slip control that controls the motor that drives the right rear wheel, the left rear wheel, or both of them so as to cancel out the influence of the inertial force generated by the slip on the unintended turning motion of the vehicle; a grip-time control that controls the motor that drives the left rear wheel, the right rear wheel, or both of them so as to cancel out the influence on unintended vehicle turning motion when the right front wheel or the left front wheel grips after the slip; The above-mentioned problem is solved by a first solving means, which is a control device that controls at least one of the above.

[0012] Further, the control device according to the present invention comprises: In the slip control, positive torque increase control for increasing the torque of a motor connected to a right rear wheel or a left rear wheel that is on the same left or right side as the slipping front wheel; a reverse torque reduction control for reducing the torque of a motor connected to a left rear wheel or a right rear wheel that is opposite to the left and right of the slipping front wheel; At least one of the following is performed: In the gripping control, positive torque reduction control that reduces the torque of a motor connected to a right rear wheel or a left rear wheel that is on the same left and right as the gripped front wheel; a reverse torque increase control for increasing the torque of a motor connected to a left rear wheel or a right rear wheel that is opposite to the gripped front wheel; A second solution can be adopted, which performs at least one of the above.

[0013] Furthermore, the present invention provides a drive source; and an open differential that transmits drive force from the drive source to both left and right rear wheels; A motor that drives each of the left and right front wheels; A control device for controlling a vehicle having a detection unit that detects slippage of at least one of the rear wheels, When slippage is detected in the right or left rear wheel, slip control that controls the motor that drives the right front wheel, the left front wheel, or both of them so as to cancel out the influence of the inertial force generated by the slip on the unintended turning motion of the vehicle; a grip-time control that controls the motor that drives the left front wheel, the right front wheel, or both of them so as to cancel out the influence on unintended vehicle turning motion when the right rear wheel or the left rear wheel grips after the slip; and A third solution can be adopted in which the control device performs at least one of the above-mentioned controls.

[0014] Further, the control device according to the present invention comprises: In the slip control, positive torque increase control that increases the torque of a motor connected to a right front wheel or a left front wheel that is on the same left or right side as the slipping rear wheel; a reverse torque reduction control for reducing the torque of a motor connected to a left front wheel or a right front wheel that is opposite to the slipping rear wheel; At least one of the following is performed: In the gripping control, positive torque reduction control that reduces the torque of a motor connected to a right front wheel or a left front wheel that is on the same left or right side as the gripped rear wheel; a reverse torque increase control for increasing the torque of a motor connected to a left front wheel or a right front wheel that is opposite to the gripped rear wheel; A fourth solution can be adopted, which performs at least one of the above.

[0015] Furthermore, the control device according to the present invention, in the first to fourth solving means, The control device may employ a fifth solution, in which the control device performs both the slip control and the grip control.

[0016] Furthermore, the control device according to the present invention, in the first to fourth solving means, A sixth solution can be adopted in which the value of the slip control or the grip control is adjusted based on a value including viscosity or friction as the inertial force. [Effects of the Invention]

[0017] According to this invention, even if a vehicle having an open differential and independent left and right motors slips, unintended vehicle turning movements can be prevented, and stable driving can be achieved. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a functional block diagram showing a first embodiment of a vehicle according to the present invention; [Figure 2] FIG. 10 is a diagram showing the driving force when the right front wheel is slipping in this invention. [Figure 3] FIG. 3 is a diagram showing the driving force when the first method of slip control is performed from FIG. 2. [Figure 4]FIG. 3 is a diagram showing the driving force when the second method of slip control is performed from FIG. 2. [Figure 5] 2 to 3 are diagrams showing the driving force when slip control is performed according to the third method. [Figure 6] FIG. 10 is a diagram showing the driving force when the right front wheel grips the wheel in this invention. [Figure 7] FIG. 7 is a diagram showing the driving force when the first grip control method is performed from FIG. 6. [Figure 8] FIG. 7 is a diagram showing the driving force when the second grip control method is performed from FIG. 6. [Figure 9] FIG. 7 is a diagram showing the driving force when the third method of grip control is performed from FIG. 6. [Figure 10] FIG. 10 is a functional block diagram showing a second embodiment of the automobile according to the present invention; [Figure 11] FIG. 1 is a flow diagram illustrating an example of a first method of slip control in the first embodiment. [Figure 12] FIG. 1 is a flow diagram illustrating a first method of grip control in the first embodiment. [Figure 13] FIG. 13 is a diagram showing an example of transitions in wheel speed, wheel acceleration, and torque in the situations of FIGS. 11 and 12. [Figure 14] Example of the flow when calculating inertial force including inertia and viscosity DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the present invention will be described below. A control device 10 according to the present invention controls an automobile. In an automobile 11, one of front wheels 12 or rear wheels 13 is connected by an open differential 16 connected to a drive source 15, outputting the same torque to the left and right wheels, while the other has a motor 17 for rotating each of the left and right wheels. Note that the present invention can be implemented in the same way regardless of whether the open differential 16 is provided on the front wheels 12 or the rear wheels 13. The drive source 15 may be a motor or an engine. The automobile 11 may be an electric vehicle that receives power from an external source to drive the motor 17 and, if the drive source 15 is a motor, or a hybrid vehicle that generates the power using an engine or a fuel cell. If the automobile 11 is a hybrid vehicle, it may be a plug-in hybrid vehicle (PHEV) that has an external charging function that allows it to be charged with power from an external source and an external power supply function that allows it to supply power to an external source.

[0020] As a first embodiment, an automobile 11 having an open differential 16 on the front wheel 12 side will be described as an example. The configuration of this automobile 11 will be described with reference to FIG. 1. FIG. 1 is a functional block diagram showing a first embodiment of an automobile 11 having a control device 10 according to the present invention. The left and right front wheels 12 (right front wheel 12a, left front wheel 12b) are connected to an open differential 16 connected to a drive source 15 that drives the front wheels, and are driven by rotation from the drive source 15. The left and right rear wheels 13 (right rear wheel 13a, left rear wheel 13b) are driven by respective motors (right motor 17a, left motor 17b). The control device 10 according to the present invention achieves control in at least one of the following ways by adjusting the output of each motor 17.

[0021] The control device 10 of this invention is a device that can directly or indirectly control at least the drive source 15 and the left and right motors 17a, 17b, and may be hardware common to the ECU of the automobile 11 itself, or may be separately provided hardware. The device has a calculation device that actually performs the control described below, a memory that stores necessary information and programs, and an interface for input and output. Furthermore, the setting values ​​may be adjustable from an in-vehicle user interface of the automobile 11.

[0022] The control device 10 also has a detection unit that detects wheel slip. This detection unit is not particularly limited as long as it can actually detect the occurrence of slip. A specific example is a configuration in which a wheel speed sensor (encoder, etc.) such as a speed sensor or acceleration sensor is provided on each wheel, and the wheel speed sensor detects a sudden increase in wheel speed (acceleration), and if this value exceeds a predetermined value, it is determined that slip has occurred.

[0023] <First response method when the front wheels 12 slip: Reducing torque of the opposite rear wheels (only reverse torque reduction control)> Next, the operation of the control device 10 will be described. First, the first response method when the right front wheel 12a slips will be described with reference to Figs. 2 and 3. Fig. 2 is a diagram showing the driving force when the right front wheel 12a slips in this invention. Fig. 3 is a diagram showing the driving force when the first method of slip control is performed from Fig. 2. If the left front wheel 12b slips, the left and right are reversed. In Fig. 2, when the right front wheel 12a slips, the driving force P applied to each wheel is represented by the length of the arrow. In the following figures, FR indicates the front wheel side (front) right, FL indicates the front wheel side (front) left, RR indicates the rear wheel side (rear) right, and RL indicates the rear wheel side (rear) left. When the right front wheel 12a slips, the driving force P FR (P FR On the other hand, even if the right front wheel 12a slips, the left front wheel 12b receives the driving force P FL (P FL >0). If the torque of the rear wheels 13 is the same on both sides (P RR =P RL), and comparing the total of the front wheel 12 and rear wheel 13 on each side, the left wheel driving force PL (=P FL +P RL )>Right wheel driving force PR (=P FR +P RR ) in the vehicle 11. In this state, a clockwise turning force is generated around the center of gravity G in the vehicle 11. In order to cancel this turning force, the control device 10 controls the driving force (torque) P RL To reduce (P RL →P RL1 (P RL1 <P RL )), and controls the left motor 17b. The amount of torque reduction is proportional to the acceleration of the spinning right front wheel 12a. In this way, the turning force that the driving forces of the four wheels impart to the center of gravity can be adjusted to a value of plus or minus 0. However, in the first method, the control device 10 reduces the driving force of the left rear wheel 13b as the right front wheel 12a spins. This has the disadvantage of reducing the overall propulsion force.

[0024] <Second Response Method When Front Wheel 12 Slips: Increase in Torque of Positive Rear Wheel (Positive Torque Increase Control Only)> Next, the second response method when the right front wheel 12a slips will be described with reference to FIG. 4. FIG. 4 is a diagram showing the driving force when the second method of slip control is performed from FIG. 2. Note that if the left front wheel 12b slips, the left and right are reversed. When the right front wheel 12a slips, as shown in FIG. 2, the left wheel driving force PL (=P FL +P RL )>Right wheel driving force PR (=P FR +P RR ) to counteract the turning force caused by this situation. As shown in FIG. 4, the control device 10 controls the driving force (P RR ) to increase (P RR →P RR1 (P RR1 >P RR)) controls the right motor 17a. The amount of torque increase is proportional to the acceleration of the spinning right front wheel 12a. In this way, the turning force that the driving force of the four wheels exerts on the center of gravity can be adjusted to a value of plus or minus 0. The second method can maintain the overall propulsive force without reducing the overall propulsive force as in the first method. On the other hand, the second method compensates for the spinning of the right front wheel 12a with the right rear wheel 13a. Therefore, there is a high possibility that the right rear wheel 13a will pass through a point where the right front wheel 12a has spun as the vehicle moves, and there is a risk that the right rear wheel 13a will also spin. For this reason, the first method provides higher stability.

[0025] <Third response method when the front wheels 12 slip: torque reduction (small) of the reverse rear wheels + torque increase (small) of the forward rear wheels (combined use of reverse torque reduction control and forward torque increase control)> Next, the third response method when the right front wheel 12a slips will be explained using FIG. 5. FIG. 5 is a diagram showing the driving force when the first method of slip control is performed from FIG. 2. Note that when the left front wheel 12b slips, the left and right are reversed. When the right front wheel 12a slips, as shown in FIG. 2, the left wheel driving force PL (=P FL +P RL )>Right wheel driving force PR (=P FR +P RR ) In order to counteract the turning force caused by this situation, the control device 10 reduces the driving force (torque) of the left rear wheel 13b (the rear wheel 13 that is in the opposite left and right direction to the right front wheel 12a (the front wheel 12 on the slipping side)) as shown in FIG. RL →P RL2 (P RL2 <P RL )) and the left motor 17b. The control device 10 also controls the right rear wheel 13a (the rear wheel 13 on the same left and right as the right front wheel 12a (the front wheel 12 on the slipping side)) to increase the driving force (P RR →P RR2 (P RR2 >P RR)) controls the right motor 17a. However, the sum of the absolute values ​​of the torque reduction amount and the torque increase amount is proportional to the acceleration of the spinning right front wheel 12a. The respective torque reduction amount and torque increase amount are smaller than the respective torque amounts in the first and second methods. In this way, the turning force imparted to the center of gravity by the driving force of the four wheels can be adjusted to a value close to zero (plus or minus). The third method is a balance between the first and second methods, and is a method that improves stability while suppressing a decrease in propulsive force.

[0026] Under the same idling conditions, the relationship between the values ​​when controlled by the first to third methods is |P RL -P RL1 |>|P RL -P RL2 | and |P RR -P RR1 |>|P RR -P RR2 | Also, as a general trend, |P RL -P RL1 |≒|P RR -P RR1 |≒|P RL -P RL2 |+|P RR -P RR2 However, the actual control values ​​for each motor 17 are adjusted to suit the characteristics of the actual electric vehicle.

[0027] <First response method when the front wheels 12 grip: torque reduction of the positive rear wheels (positive torque reduction control only)> Next, the first response method when the right front wheel 12a grips (ends spinning) will be explained using Figs. 6 and 7. Fig. 6 is a diagram showing the driving force when the right front wheel 12a grips in this invention. Fig. 7 is a diagram showing the driving force when grip control of the first method is performed from Fig. 6. Note that when the left front wheel 12b grips, the left and right are reversed. Fig. 6 is a diagram showing the driving force applied to each wheel by the length of the arrow when the right front wheel 12a grips. When the right front wheel 12a grips, the right front wheel 12a receives the same torque (P FR =P FL) is applied to the right front wheel 12a. T ((Figures 6 to 9 show P T-FR (Written as) = ​​dω R / dt×T(ω R is the rotational speed of the slipping front wheel 12, and T is the rotational moment). Therefore, the total driving force of the right front wheel 12a is larger than that of the left front wheel 12b ((P FR +P T-FR )>P FL ). If the torque on both the left and right rear wheels 13 is the same (F RR =F RL ), and comparing the total of the front wheel 12 and rear wheel 13 on each side, the left wheel driving force PL (= P FL +P RL )<Right wheel driving force PR(=P FR +P RR +P T-FR ) in the automobile 11. In this state, a counterclockwise turning force is generated around the center of gravity G in the automobile 11. In order to cancel this turning force, the control device 10 controls the right rear wheel 13a (rear wheel 13 on the same side as the right front wheel 12a (front wheel 12 on the gripping side)) to reduce the driving force (torque) (P RR →P RR3 (P RR3 <P RR )) controls the right motor 17a. The amount of torque reduction is determined by the inertial force P of the spinning right front wheel 12a. T In this way, if the total driving force on the left and right sides is made equal, (P FL +P RL =P FR +P RR3 +P T-FR ), the turning force can be adjusted by plus or minus to approach a value of 0.

[0028] <Second response method when the front wheels grip: Increase torque on the opposite rear wheels (only increase torque control)> Next, the second response method when the right front wheel 12a grips (ends of spinning) will be described with reference to FIG. 8. FIG. 8 is a diagram showing the driving force when the second method of grip control is performed from FIG. 6. Note that if the left front wheel 12b grips, the left and right are reversed. When the right front wheel 12a grips, as shown in FIG. 6, the left wheel driving force PL (=P FL +P RL )<Right wheel driving force PR(=P FR +P RR +P T-FR ) In order to counteract the turning force caused by this situation, the control device 10 increases the driving force (torque) of the left rear wheel 13b (the rear wheel 13 that is opposite to the right front wheel 12a (the front wheel 12 on the gripping side)) as shown in FIG. RL →P RL3 (P RL3 >P RL )), the left motor 17b is controlled. The amount of torque increase is proportional to the acceleration of the spinning right front wheel 12a. In this way, when the sum of the driving forces on the left and right wheels is made equal, (P FL +P RL3 =P FR +P RR +P T-FR ), the turning force can be adjusted by plus or minus to approach a value of 0.

[0029] <Third response method when the front wheels 12 grip: torque reduction (small) of the forward rear wheels + torque increase (small) of the reverse rear wheels (combined use of forward torque reduction control and reverse torque increase control)> Next, the third response method when the right front wheel 12a grips (ends of spinning) will be described with reference to FIG. 9. FIG. 9 is a diagram showing the driving force when grip control of the third method is performed from FIG. 6. Note that if the left front wheel 12b grips, the left and right are reversed. When the right front wheel 12a grips, as shown in FIG. 6, the left wheel driving force PL (=P FL +P RL )<Right wheel driving force PR(=P FR +P RR +P T-FR) In order to counteract the turning force caused by this situation, the control device 10 reduces the driving force (torque) of the right rear wheel 13a (the rear wheel 13 on the same left and right as the right front wheel 12a (the gripping side)) as shown in FIG. RR →P RR4 (P RR4 <P RR )) and the right motor 17a. The control device 10 also controls the left rear wheel 13b (the rear wheel 13 that is in the opposite left and right direction to the right front wheel 12a (the front wheel 12 on the gripping side)) so as to increase the driving force (torque) of the left rear wheel 13b (the rear wheel 13 that is in the opposite left and right direction to the right front wheel 12a (the front wheel 12 on the gripping side)). RL →P RL4 (P RL4 >P RL )) and controls the left motor 17b. However, the sum of the absolute values ​​of the torque reduction amount and the torque increase amount is equal to the inertial force P T-FR In this way, if the total driving force on the left and right sides is made equal, (P FL +P RL4 =P FR +P RR4 +P T-FR ), the turning force can be adjusted to a value approaching 0 by plus or minus. This third method is a balance between the first and second methods.

[0030] Under the same gripping conditions, the relationship between the values ​​when controlled by the first to third methods is |P RL -P RL3 |>|P RL -P RL4 | and |P RR -P RR3 |>|P RR -P RR4 | Also, as a general trend, |P RL -P RL3 |≒|P RR -P RR3 |≒|P RL -P RL4 |+|P RR -P RR4 However, the actual control values ​​for each motor 17 are adjusted to suit the characteristics of the actual electric vehicle.

[0031] <If there is an open differential on the rear wheel side> As a second embodiment, an electric vehicle 21 having an open differential 16 on the rear wheel 13 side will be described with reference to FIG. 10. FIG. 10 is a functional block diagram showing the second embodiment of the electric vehicle according to the present invention. The left and right rear wheels 13 (right rear wheel 13a, left rear wheel 13b) are connected by an open differential 16 that is connected to a drive source 15 that drives the rear wheels. The left and right rear wheels 13 are driven by rotation from the drive source 15. The left and right front wheels 12 (right front wheel 12a, left front wheel 12b) are driven by respective motors (right motor 17a, left motor 17b).

[0032] In the case of this electric vehicle 21, the control device 10 executes the procedures for slipping and gripping in the reverse order of the first to third methods described above. However, when the front wheels 12 spin first, the control device 10 is unable to execute the control relating to the first to third methods for slipping, and starts executing the control relating to the first to third methods for slipping from the point when the rear wheels 13 spin. The control device 10 controls the right motor 17a and left motor 17b on the front wheels 12 side, thereby reducing the reduction in driving force due to spinning of the rear wheels 13 and the inertial force P T This cancels out the turning force that occurs due to the increase in driving force caused by the addition of the torque. This allows the automobile 11 to travel stably. The procedure performed by the control device 10 is the same as that for the automobile 11.

[0033] <Example of flow and time chart> Next, a specific example of the procedure by which the control device 10 controls the motor 17 during slip and grip will be described with reference to the flowcharts in FIGS. 11 and 12. First, the control device 10 (S101) monitors the rotational acceleration of the left and right wheels connected by the open differential 16 at predetermined time intervals (e.g., every few milliseconds) while the vehicle is traveling (S102). In the case of the vehicle 11 in FIG. 1, these are the front wheels 12a and 12b, but in the case of the vehicle 21 shown in FIG. 10, these are the rear wheels 13a and 13b. The following description will be given using the vehicle 11 in FIG. 1 as an example. For this reason, it is desirable that an acceleration sensor be provided on each wheel connected by the open differential 16 (front wheels 12a and 12b in the example shown in FIG. 1), and that the values ​​of these acceleration sensors be determined by the control device 10 and used as a detection unit.

[0034] Next, the control device 10 continues to compare the monitored accelerations of the left and right wheels to determine whether or not a slip is occurring. Specifically, if the control device 10 determines that the acceleration of the right front wheel 12a exceeds the acceleration of the left front wheel 12b by more than a predetermined value A (S103 → Yes), the control device 10 determines that the right front wheel 12a has slipped (S111). On the other hand, if the control device 10 determines that the acceleration of the right front wheel 12a does not exceed the acceleration of the left front wheel 12b by more than the predetermined value A (S103 → No), or if the control device 10 determines that the acceleration of the left front wheel 12b exceeds the acceleration of the right front wheel 12a by more than the predetermined value A (S104 → Yes), the control device 10 determines that the left front wheel 12b has slipped (S121). If neither of these is true, the control device 10 determines that the vehicle is in a non-slip state, and continues monitoring and comparison (S105 → S103). The predetermined value A may be a value initially set for the model of the automobile 11, or may be a value adjusted depending on the driving environment. The determinations in S103 and S104 may be performed in reverse order.

[0035] When the control device 10 determines that a slip has occurred (S111, S121), it multiplies the rotational acceleration of the wheel (12a, 12b) that has been determined to have slipped by the moment of inertia of the tire and axle 14 to obtain an inertial force P T (S112, S122). The control device 10 calculates the inertial force P TIn response to this, for example, when the first method is adopted for control, the torque of the motors (17b, 17a) that rotate the rear wheels (or front wheels) 13b, 13a (with the same symbols) that are opposite to the slipping front wheels (or rear wheels) 12a, 12b is calculated by the inertia force P T The amount is subtracted (S113, 123).

[0036] In another embodiment, the control device 10 may make the determinations in S103 and S104 based on the ratio of the left and right accelerations instead of the difference between the left and right accelerations. In this case, the predetermined value A may be changed to a value appropriate for this.

[0037] Once the control device 10 determines that a slip state has occurred, it subsequently determines that a grip state has occurred and performs grip control (S201). Note that the control device 10 calculates the inertia force to be calculated during grip control separately from that calculated during slip control.

[0038] The control device 10 continues to compare the monitored accelerations of the left and right wheels even after a slip determination is made, and determines whether or not they have begun to grip. In this embodiment, an example will be described in which the right front wheel 12a has slipped. If the control device 10 determines that the acceleration of the right front wheel 12a is greater than the acceleration of the left front wheel 12b by more than a predetermined value B (S202 → Yes), it determines that the slipping right front wheel 12a has begun to grip (S211). On the other hand, if the control device 10 determines that the acceleration of the right front wheel 12a is not greater than the acceleration of the left front wheel 12b by more than the predetermined value B (S202 → No), and if the control device 10 determines that the acceleration of the left front wheel 12b is greater than the acceleration of the right front wheel 12a by more than the predetermined value B (S203 → Yes), it determines that the slipping left front wheel 12b has begun to grip (S221). If neither of these is true, the control device 10 continues to perform the comparison (S203 → No → S202). The predetermined value B is a value that is determined separately from the predetermined value A. The determinations in S202 and S203 may be performed in reverse order.

[0039] Next, when the control device 10 determines that gripping has begun (S211, S221), it multiplies the rotational acceleration of the wheel (front wheels 12a, 12b) that has been determined to have begun gripping by the moment of inertia between the front wheels 12 and the axle 14 to calculate the inertial force P T (S212, S222). Then, the control device 10 calculates the inertial force P T In response to this, when the above-mentioned first method is adopted for control, for example, the torque of the motors (17a, 17b) that rotate the rear wheels 13a, 13b (in the same order of symbols) that are on the same left and right as the front wheels (or rear wheels) 12a, 12b that have started to grip is calculated based on the inertial force P T Then, the control device 10 continues to subtract this torque as long as the difference in acceleration is greater than the predetermined value B (S214, S224 → Yes), and when it determines that the difference in acceleration is equal to or less than the predetermined value B (S214, S224 → No), it determines that the wheels have stopped spinning, have fully gripped the road surface, and have completed gripping (S215, S225).

[0040] FIG. 13 illustrates the conceptual transitions of wheel speed, wheel acceleration, and rear wheel torque controlled accordingly in a vehicle 11 equipped with a control device 10 according to the present invention during slip and grip. In each figure, the thick solid line indicates the right wheel, and the dashed line indicates the left wheel. Normally, the left and right wheel speeds are equal, but as slip begins, only the wheel that has started to slip (here, the right front wheel 12a) increases in speed, resulting in a speed difference between the left and right wheels. At this time, the wheel acceleration of the right front wheel 12a rises sharply immediately after slip begins and exceeds a predetermined value A. The control device 10 detects this slip and performs slip control (here, the first method is used as an example). In this slip control, the control device 10 controls the motor 17b to quickly reduce the torque of the left rear wheel 13b.

[0041] The speed difference between the left and right front wheels 12 decreases when the wheel stops slipping and begins to grip. At this time, the acceleration becomes negative and falls below a predetermined value B (set as a negative value with the positive and negative signs reversed) (exceeding the predetermined value B when compared in absolute value). This is because the front wheel 12 (right front wheel 12a in this case), which was slipping and rotating at high speed, is now rapidly gripping the road surface and decelerating. In grip control (first method is used here as an example) that detects this grip, the control device 10 controls the motor 17a to quickly reduce the torque of the right rear wheel 13a.

[0042] Note that the response to the corrections made by the above-described control using the left and right motors 17a, 17b will be delayed regardless of whether the open differential 16 and the left and right motors 17a, 17b are located in the front or rear. This is because the control must be performed after slip and grip are detected. For this reason, it is preferable that the control device 10 add phase lead compensation or Smith compensation to the control using the left and right motors 17a, 17b. This improves responsiveness. This allows the control device 10 to reduce the time lag until the turning force is canceled out.

[0043] Furthermore, the control device 10 may set the torque increase and decrease amounts of the left and right motors 17a, 17b when changing the driving forces to values ​​that cancel out the turning force, taking into account the center of gravity position of the automobiles 11, 21. By controlling the motors 17a, 17b with such values, the control device 10 can suppress the turning movement of the vehicle.

[0044] Furthermore, the control device 10 adjusts the torque increase and decrease amounts of the left and right motors 17a and 17b in accordance with the inertial force P T The calculation may include not only the inertial force due to the rotation of the wheels themselves, but also the viscosity and friction of the axles 14a and 14b and the gears of the open differential 16, and the inertia of the drive source 15 whose rotation speed increases. TThis is preferable because it is possible to more accurately suppress the turning motion of the vehicle. T An example of the relationship when calculating the inertia, viscosity, and friction is shown in Fig. 14. The control device 10 calculates the inertia J and viscosity B from the rotational acceleration ω of the wheel (front wheel 12 or rear wheel 13), takes into account the influence of gear friction, and calculates the inertial force P T can be obtained.

[0045] The control device 10 calculates the inertial force P T When determining the values ​​to control the outputs of the motors 17a and 17b, the values ​​may be calculated based on measured values ​​or predetermined values, or a control map that defines control values ​​suited to the situation may be recorded in the motor itself or an external device that can be connected to it, and the control may be performed by referring to this control map. For example, an embodiment in which a control map that takes viscosity and friction into consideration is prepared is possible. [Explanation of symbols]

[0046] 10 Control device 11, 21 Automobiles 12 Front wheels 12a Right front wheel 12b Left front wheel 13 rear wheel 13a Right rear wheel 13b Left rear wheel 14 axles 14a Right front axle 14b Left front axle 15 Power Source 16 Open differential 17 Motor 17a Right motor 17b Left motor

Claims

1. a drive source; and an open differential that transmits drive force from the drive source to both left and right front wheels; A motor that drives each of the left and right rear wheels; A control device for controlling a vehicle having a detection unit that detects slippage of at least one of the front wheels, If slippage is detected in the right or left front wheel, slip control that controls the motor that drives the right rear wheel, the left rear wheel, or both of them so as to cancel out the influence of the inertial force generated by the slip on the unintended turning motion of the vehicle; a grip-time control that controls the motor that drives the left rear wheel, the right rear wheel, or both of them so as to cancel out the influence on unintended vehicle turning motion when the right front wheel or the left front wheel grips after the slip; A control device that controls at least one of the above.

2. In the slip control, positive torque increase control for increasing the torque of a motor connected to a right rear wheel or a left rear wheel that is on the same left or right side as the slipping front wheel; a reverse torque reduction control for reducing the torque of a motor connected to a left rear wheel or a right rear wheel that is opposite to the left and right of the slipping front wheel; At least one of the following is performed: In the gripping control, positive torque reduction control that reduces the torque of a motor connected to a right rear wheel or a left rear wheel that is on the same left and right as the gripped front wheel; a reverse torque increase control for increasing the torque of a motor connected to a left rear wheel or a right rear wheel that is opposite to the gripped front wheel; The control device according to claim 1 , further comprising:

3. a drive source; and an open differential that transmits drive force from the drive source to both left and right rear wheels; A motor that drives each of the left and right front wheels; A control device for controlling a vehicle having a detection unit that detects slippage of at least one of the rear wheels, When slippage is detected in the right or left rear wheel, slip control that controls the motor that drives the right front wheel, the left front wheel, or both of them so as to cancel out the influence of the inertial force generated by the slip on the unintended turning motion of the vehicle; a grip-time control that controls the motor that drives the left front wheel, the right front wheel, or both of them so as to cancel out the influence on unintended vehicle turning motion when the right rear wheel or the left rear wheel grips after the slip; and A control device that controls at least one of the above.

4. In the slip control, positive torque increase control that increases the torque of a motor connected to a right front wheel or a left front wheel that is on the same left or right side as the slipping rear wheel; a reverse torque reduction control for reducing the torque of a motor connected to a left front wheel or a right front wheel that is opposite to the slipping rear wheel; At least one of the following is performed: In the gripping control, positive torque reduction control that reduces the torque of a motor connected to a right front wheel or a left front wheel that is on the same left or right side as the gripped rear wheel; a reverse torque increase control for increasing the torque of a motor connected to a left front wheel or a right front wheel that is opposite to the gripped rear wheel; The control device according to claim 3 , further comprising:

5. The control device according to any one of claims 1 to 4, wherein the control device performs both the slip control and the grip control.

6. 5. The control device according to claim 1, wherein a value of the slip control or the grip control is adjusted based on a value including viscosity or friction as the inertial force.

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