Driving force control method and driving force control device

Abstract

To provide a drive force control method which can suppress a car sickness of an occupant accompanied by an acceleration change of a vehicle by a simpler constitution, and a drive force control device.SOLUTION: In a drive force control method for controlling a drive force distribution of a first drive source connected to front wheels so that a pitch angle of a vehicle takes a desired behavior, and a second drive source connected to rear wheels, the drive force control method performs pitch rate adjustment processing for adjusting a pitch rate so as to generate a pitch displacement in a direction in which fore-and-aft acceleration corresponding to required acceleration is cancelled on the basis of the required acceleration with respect to the vehicle, and in the pitch rate adjustment processing, the drive force control method adjusts the pitch rate by controlling a drive force of the first drive source and a drive force of the second drive source to different orientations.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a driving force control method and a driving force control device. [Background technology]

[0002] Patent Document 1 proposes a vehicle occupant posture control device that predicts changes in vehicle acceleration and changes the support state of the vehicle seat to stabilize the occupant's posture and suppress car sickness in the occupant. In particular, this vehicle occupant posture control device operates movable parts (seat back support parts, arm rests, etc.) of the vehicle seat to support the occupant's body in accordance with the acceleration before the acceleration occurs due to steering of the vehicle, such as when changing lanes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-71370 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the device of Patent Document 1 requires the adoption of a mechanical structure for realizing movement of the vehicle seat, which raises concerns about the complication of the vehicle structure and increased manufacturing costs.

[0005] Therefore, an object of the present invention is to provide a driving force control method and a driving force control device that can suppress car sickness of occupants caused by changes in the acceleration of the vehicle with a simpler configuration. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a driving force control method for controlling the distribution of driving force to a first driving source connected to the front wheels and a second driving source connected to the rear wheels so that the pitch angle of the vehicle behaves as desired. In this driving force control method, a pitch rate adjustment process is executed to adjust the pitch rate based on a required acceleration for the vehicle so as to generate a pitch displacement in a direction that cancels the longitudinal acceleration corresponding to the required acceleration. In the pitch rate adjustment process, the driving force of the first driving source and the driving force of the second driving source are adjusted. The driving force is distributed so that the positive and negative are different from each other. The pitch rate is adjusted by controlling In addition, the pitch rate adjustment process is executed after a command to change the required acceleration is issued and before the timing at which the longitudinal acceleration actually changes. Effect of the Invention

[0007] According to the present invention, it is possible to suppress car sickness in occupants caused by changes in the acceleration of the vehicle with a simpler configuration. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating the configuration of a vehicle in which a driving force control method according to an embodiment of the present invention is executed. [Diagram 2] FIG. 2 is a block diagram illustrating the functional configuration of a driving force control device that executes the driving force control method. [Diagram 3] FIG. 3 is a diagram for explaining the pitch movement of a vehicle. [Figure 4] FIG. 4 is a flowchart illustrating the driving force control method. [Diagram 5] FIG. 5 is a map illustrating the operating points of the vehicle when the first corrected pitch rate is set. [Figure 6] FIG. 6 is a time chart showing the control results when the pitch rate adjustment process is executed when the vehicle is accelerating. [Figure 7] FIG. 7 is a time chart showing the control results when the pitch rate adjustment process is executed when the vehicle is decelerating. [Figure 8] FIG. 8 is a time chart showing an example of a control result when the second corrected pitch rate is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

[0010] FIG. 1 is a diagram illustrating the configuration of a vehicle 100 in which a driving force control method according to the present embodiment is executed.

[0011] The vehicle 100 of this embodiment is assumed to be an electric vehicle or a hybrid vehicle that is equipped with a drive motor 10 as a drive source and can run using the drive force of the drive motor 10.

[0012] The drive motor 10 is composed of a front wheel motor 10f serving as a first electric motor provided at a position at the front of the vehicle 100 (hereinafter referred to as the "front wheel side") and driving the front wheels 11f, and a rear wheel motor 10r serving as a second electric motor provided at a position at the rear of the vehicle 100 (hereinafter referred to as the "rear wheel side") and driving the rear wheels 11r.

[0013] The front wheel motor 10f is configured as a three-phase AC motor. The front wheel motor 10f generates driving force by receiving a supply of electric power from a battery as a power source. The driving force generated by the front wheel motor 10f is transmitted to the front wheels 11f via a front wheel transmission 16f and a front wheel drive shaft 21f. The front wheel motor 10f also converts regenerative driving force generated when the front wheel motor 10f rotates in response to the rotation of the front wheels 11f while the vehicle 100 is running into AC power. The power supplied to the front wheel motor 10f is adjusted by a front wheel inverter 12f. In particular, the front wheel inverter 12f calculates the total driving force required for the vehicle 100 (hereinafter referred to as "total required driving force F fr ") and a driving force based on a distribution ratio κ determined for the front wheel motor 10f (hereinafter referred to as "front wheel driving force F f " drives the front wheel motor 10f.

[0014] Meanwhile, the rear wheel motor 10r is configured as a three-phase AC motor. The rear wheel motor 10r generates driving force by receiving power from a battery as a power source. The driving force generated by the rear wheel motor 10r is transmitted to the rear wheel 11r via the rear wheel transmission 16r and the rear wheel drive shaft 21r. The rear wheel motor 10r also converts regenerative driving force generated when the rear wheel 11r rotates while the vehicle 100 is running into AC power. The power supplied to the rear wheel motor 10r is adjusted by the rear wheel inverter 12r. In particular, the rear wheel inverter 12r converts the total required driving force F fr and the driving force based on the distribution ratio κ determined for the rear wheel motor 10r (hereinafter, the rear wheel driving force F r " drives the rear wheel motor 10r.

[0015] Furthermore, the vehicle 100 is configured to determine the driving force distribution (i.e., the front wheel driving force F f and rear wheel drive force F r A controller 50 is provided as a driving force control device for controlling the driving force.

[0016] The controller 50 is composed of a computer equipped with a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface), and is programmed to execute each process in vehicle control described below. In particular, the functions of the controller 50 can be realized by any in-vehicle computer such as a vehicle controller (VCM: Vehicle Control Module), a vehicle motion controller (VMC: Vehicle Motion Controller), and a motor controller, and / or a computer installed outside the vehicle 100. The controller 50 may be realized by a single piece of computer hardware, or may be realized by distributing various processes among multiple computer hardware.

[0017] Furthermore, the various input information (estimated values ​​or detected values) input to the controller 50 includes the operation amount of an accelerator pedal mounted on the vehicle 100 (hereinafter also referred to as "accelerator opening APO"), the pitch angle θ, and the acceleration in the longitudinal direction of the vehicle 100 (hereinafter also referred to as "longitudinal acceleration a"). The input information may also include, as necessary, a detected value of the steering angle of the vehicle 100, a detected value of the road surface gradient (gradient angle) of the road on which the vehicle 100 is traveling, and / or a detected value of friction (road surface μ) on the road on which the vehicle 100 is traveling.

[0018] In this embodiment, the accelerator opening APO is a parameter that represents the value of the longitudinal acceleration a required for the vehicle 100. On the other hand, if the vehicle 100 is equipped with a so-called automatic driving function and at least the required acceleration a fr When the value of the longitudinal acceleration a is determined by a predetermined autonomous driving controller (such as an ADAS "Advanced Driver Assistance Systems" controller or an AD "Autonomous Driving" controller), the value of the longitudinal acceleration a required based on the command driving force is determined. Therefore, in the following, this will be collectively referred to as the "required acceleration a fr " is expressed as follows.

[0019] The functionality of the controller 50 will now be described in more detail.

[0020] 2 is a block diagram illustrating the configuration of the controller 50. As shown in the figure, the controller 50 has a total required driving force calculation unit 52, a basic driving force distribution unit 53, a required jerk calculation unit 55, and a pitch rate adjustment unit 56.

[0021] The total required driving force calculation unit 52 receives the accelerator opening APO and other parameters such as the vehicle speed as appropriate, and calculates a total required driving force F fr For example, the total required driving force calculation unit 52 calculates an appropriate total required driving force F according to the accelerator opening APO and the vehicle speed. frA map that defines the total required driving force F is read from an arbitrary memory and applied to the input accelerator opening APO and vehicle speed. fr The total required driving force calculation unit 52 can calculate the calculated total required driving force F fr is output to the basic driving force distribution unit 53.

[0022] The basic driving force distribution unit 53 calculates the total required driving force F fr With input, the predetermined basic allocation ratio κ b From, front wheel drive force F f The basic value of the front wheel drive force F f_b ") and rear wheel drive force F r The basic value of the rear wheel drive force F r_b Here, the basic allocation ratio κ b is a basic value of the distribution ratio κ determined by an experiment or a simulation so that the vehicle characteristics of the vehicle 100 have desired characteristics. Note that the term vehicle characteristics used in this embodiment mainly includes characteristics related to the efficiency of energy consumed in the operation of the vehicle 100, such as running (fuel economy performance or power economy performance), characteristics related to the difficulty of slipping in the front wheels 11f or the rear wheels 11r (slip performance), and required acceleration a fr This includes the tracking ability of longitudinal acceleration a (dynamic performance).

[0023] In addition, the basic allocation ratio κ b The specific values ​​for may be changed as appropriate depending on the specifications of the vehicle 100 and the driving scene. For example, when traveling straight on a flat paved road at a constant speed, the front wheel drive force F f and rear wheel drive force F r The basic allocation ratio κ is set so that b The basic distribution ratio κ can be set to 50 (front wheels): 50 (rear wheels). b Based on this, the basic value of the pitch angle θ of the vehicle 100 (hereinafter, the “basic pitch angle θ _b *"), and the basic value of the pitch rate ω (hereinafter referred to as "basic pitch rate ω _b * The meanings of the pitch angle θ and the pitch rate ω in this embodiment will be described below.

[0024] FIG. 3 is a diagram showing a schematic diagram of the pitch motion of the vehicle 100. As shown in the figure, the pitch angle θ in this embodiment is defined as a displacement in the pitch direction (the direction of rotation around an axis passing through the center of gravity G and extending in the vehicle width direction) with respect to the horizontal direction around the center of gravity G of the vehicle 100. In particular, in this embodiment, the sign of the pitch angle θ is set so that the direction in which the front wheels 11f of the vehicle 100 are lifted (nose-up direction) is positive, and the direction in which the rear wheels 11r are lifted (nose-down direction) is negative. Furthermore, the pitch rate ω is defined as the time rate of change of this pitch angle θ (i.e., the pitch angular velocity). The pitch angle θ and the pitch rate ω change according to the above-mentioned distribution ratio κ of the driving force and various driving environments (such as road surface unevenness and road surface gradient). In other words, the front wheel driving force F f and rear wheel drive force F r By manipulating the magnitude of each of these (driving force distribution), the pitch angle θ and the pitch rate ω can be controlled.

[0025] Returning to FIG. 2, the basic driving force distribution unit 53 calculates the basic front wheel driving force F f_b and basic rear wheel drive force F r_b to the pitch rate adjustment unit 56.

[0026] The pitch rate adjustment unit 56 determines the required acceleration a fr , basic front wheel drive force F f_b , and the basic rear wheel driving force F r_b The pitch rate adjustment unit 56 then calculates the required acceleration a fr Based on this, the corrected front wheel driving force F to be set under a predetermined condition when the vehicle 100 is accelerating or decelerating is calculated. f_c and corrected rear wheel driving force F r_c In particular, the pitch rate adjustment unit 56 calculates a corrected pitch rate ω _c *The pitch rate adjustment process described below is executed to determine

[0027] Then, the pitch rate adjustment unit 56 converts the pitch rate ω into a corrected pitch rate ω obtained by the pitch rate adjustment process. _c * When the front wheel drive force F f and rear wheel drive force F r and the corrected front wheel drive force F f_c and corrected rear wheel driving force F r_c is required.

[0028] More specifically, the pitch rate adjustment unit 56 adjusts the pitch rate ω to a corrected pitch rate ω when the vehicle 100 accelerates or decelerates. _c * Corrected front wheel drive force F f_c and corrected rear wheel driving force F r_c In more detail, when the pitch angle θ is decreased (when the vehicle 100 is moved nose down), the pitch rate adjustment unit 56 calculates a corrected pitch rate ω _c * Correct the front wheel drive force F so that it is a negative value. f_c and corrected rear wheel driving force F r_c When the pitch angle θ is increased (when the vehicle 100 is brought into nose-up position), the pitch rate adjustment unit 56 calculates a correction pitch rate ω _c * Correct the front wheel drive force F so that it is a positive value. f_c and corrected rear wheel driving force F r_c Calculate the following.

[0029] In particular, the pitch rate adjustment unit 56 refers to information on the anti-dive angle φ of the front suspension, which is determined by the structure of the vehicle 100, from a predetermined storage area, and calculates the corrected pitch rate ω _c * The information on the anti-dive angle φ is input to the above-mentioned storage area at an initial stage, such as at the time of shipment from the factory.

[0030] More specifically, when the anti-dive angle φ of the vehicle 100 is positive, the pitch rate adjustment unit 56 adjusts the corrected front wheel drive force Ff_c Increasing and / or correcting rear wheel drive force F r_c By setting the corrected pitch rate ω _c * is set to a negative value (the nose is lowered). When the anti-dive angle φ is positive, the pitch rate adjustment unit 56 adjusts the corrected front wheel drive force F f_c and / or correct rear wheel drive force F r_c By increasing the pitch rate, the corrected pitch rate ω _c * is set to a positive value (nose-up). In particular, the pitch rate adjustment unit 56 of this embodiment adjusts the pitch rate when the anti-dive angle φ is positive and the vehicle 100 is in an accelerating state (required acceleration a fr >0), the rear wheel drive force F r The pitch rate correction ω is set to a negative value to reduce the pitch angle θ. _c * Furthermore, the pitch rate adjustment unit 56 of this embodiment determines the required acceleration a when the anti-dive angle φ is positive and the vehicle 100 is in a deceleration state (required acceleration a fr <0), the front wheel drive force F f The pitch angle θ is increased by setting the corrected pitch rate ω to a negative value. _c * Determine.

[0031] On the other hand, when the anti-dive angle φ of the vehicle 100 is negative, the pitch rate adjustment unit 56 adjusts the corrected front wheel drive force F f_c and / or correct rear wheel drive force F r_c By increasing the pitch rate, the corrected pitch rate ω _c * is set to a negative value (the nose is lowered). When the anti-dive angle φ is negative, the pitch rate adjustment unit 56 adjusts the corrected front wheel drive force F f_c Increasing and / or correcting rear wheel drive force F r_c By setting the corrected pitch rate ω _c * is set to a positive value (nose-up). In particular, the pitch rate adjustment unit 56 of this embodiment adjusts the pitch rate when the anti-dive angle φ is positive and the vehicle 100 is in an accelerating state (required acceleration a fr>0), the front wheel drive force F f The pitch rate correction ω is set to a negative value to reduce the pitch angle θ. _c * Furthermore, the pitch rate adjustment unit 56 of this embodiment determines the required acceleration a when the anti-dive angle φ is positive and the vehicle 100 is in a deceleration state (required acceleration a fr <0), the rear wheel driving force F r The pitch angle θ is increased by setting the corrected pitch rate ω to a negative value. _c * Determine.

[0032] Then, the pitch rate adjustment unit 56 applies a corrected front wheel driving force F f_c and corrected rear wheel driving force F r_c On the other hand, under conditions other than the above-mentioned predetermined conditions, the pitch rate adjustment unit 56 outputs the basic front wheel driving force F f_b and basic rear wheel drive force F r_b Output.

[0033] The driving force control method of this embodiment, including the pitch rate adjustment process, will be described in further detail below.

[0034] 4 is a flowchart illustrating the driving force control method of this embodiment. The controller 50 (particularly the pitch rate adjustment unit 56) repeatedly executes the routine shown in the flowchart of FIG. 4 at predetermined calculation intervals.

[0035] As shown in the figure, based on various input information, the controller 50 of this embodiment performs the following operations: determining whether the vehicle 100 is operating under automatic driving (step S1000); determining whether the acceleration fluctuation (rate of change of longitudinal acceleration a) is greater than or equal to a certain value (step S1100); determining whether the steering angle of the vehicle 100 is less than or equal to a certain value (step S1200); determining whether the road surface gradient of the vehicle 100 is less than or equal to a certain value (step S1300); and determining whether the friction of the road surface (road surface μ) on which the vehicle 100 is traveling is greater than or equal to a certain value (step S1400).

[0036] Then, when the determination results of both steps S1000 and S1100 are positive, the controller 50 executes the processes of steps S1200 and after. On the other hand, when the determination results of steps S1000 or S1100 are negative, the controller 50 sets the pitch rate ω to the basic pitch rate ω _b * (step S1700).

[0037] Furthermore, when the determination results of steps S1200 to S1400 are all positive, the controller 50 _c * The first corrected pitch rate ω _c1 * On the other hand, if at least one of the judgment results of these judgments is negative, the controller 50 sets the corrected pitch rate ω _c * The second corrected pitch rate ω _c2 * The first corrected pitch rate ω _c1 * and the second corrected pitch rate ω _c2 * The details will be explained below.

[0038] Figure 5 shows the first corrected pitch rate ω _c1 *5 is a map for explaining an example of operating points of the vehicle 100 when the allocation ratio κ is set. In this map, a set of operating points determined according to each allocation ratio κ is represented by a broken line. That is, each broken line represents a set of operating points of a constant pitch rate ω determined according to each allocation ratio κ. In particular, although a specific value of the allocation ratio κ (e.g., 50:50) is described in FIG. 5 for the purpose of aiding understanding, this is not intended to limit the configuration of this embodiment.

[0039] As can be seen from FIG. 5, the first corrected pitch rate ω _c1 * is set so as to generate a pitch force to counteract the inertial force acting on the occupant in accordance with the acceleration / deceleration (positive or negative longitudinal acceleration a) of the vehicle 100. More specifically, when the vehicle 100 is accelerating and an inertial force acts on the occupant in a direction pressing the occupant against the seat, the first corrected pitch rate ω is set so as to reduce the pitch angle θ (so as to make the vehicle 100 pitch nose down) in order to generate a pitch force in a direction to counteract this (a pitch force in a direction to move the occupant away from the seat). _c1 * (See FIG. 5(i)).

[0040] On the other hand, when the vehicle 100 is decelerating due to the inertial force acting in a direction moving the occupant away from the seat, the first corrective pitch rate ω is increased so as to increase the pitch angle θ (so as to make the vehicle 100 pitch up) in order to generate a pitch force in a direction that counteracts the inertial force (a pitch force in a direction that presses the occupant against the seat). _c1 * (See FIG. 5 (ii)).

[0041] Next, referring to the time chart of FIG. 6, when the vehicle 100 accelerates, the first corrected pitch rate ω _c1 * The control results when the following is set will be described in more detail. In particular, Fig. 6(A) shows the change over time of the longitudinal acceleration a, and Fig. 6(B) shows the change over time of the pitch angle θ.

[0042] As shown in the figure, at a time t1 before the timing (time t2) at which acceleration of the vehicle 100 is detected, the first corrected pitch rate ω _c1 * By setting this, the pitch angle θ decreases (nose down) in response to an increase in the longitudinal acceleration a.

[0043] In particular, in this embodiment, the control to decrease the pitch angle θ is started before time t2 when acceleration actually starts. This allows the occupants of the vehicle 100 to recognize the change in the pitch angle θ before the actual change in the longitudinal acceleration a. Therefore, compared to the case where the pitch angle θ decreases after time t2 when the longitudinal acceleration a actually starts to change (dashed line graph in FIG. 6), the occupants can be made aware that a change in the longitudinal acceleration a will occur, and can be encouraged to prepare for the change.

[0044] 7 shows the first corrected pitch rate ω _c1 * FIG. 13 is a diagram illustrating a control result when

[0045] As shown in the figure, at a time t1 before the timing (time t2) at which deceleration of the vehicle 100 is detected, the first corrected pitch rate ω _c1 * By setting this, the pitch angle θ increases (nose up) in accordance with the decrease in the longitudinal acceleration a.

[0046] 7, the control to increase the pitch angle θ is started before the time t2 when deceleration actually starts. This allows the occupants of the vehicle 100 to be aware in advance of the occurrence of a change in the longitudinal acceleration a, and encourages them to prepare for the change.

[0047] Next, the second corrected pitch rate ω _c2 * The second corrected pitch rate ω _c2 * is set when any one of the determination results of steps S1200 to S1400 is negative. _c2* is the first corrected pitch rate ω _c1 * is set so that the amount of decrease in the pitch angle θ is suppressed compared to

[0048] In particular, when the steering angle exceeds a certain value (No in step S1200), the controller 50 changes the pitch rate ω to a second corrected pitch rate ω _c2 * In particular, the second corrected pitch rate ω _c2 * The absolute value of is set to a smaller value as the steering angle increases.

[0049] As a result, when the vehicle 100 is turning with a large steering angle, the pitch displacement is suppressed according to the magnitude of the steering angle (degree of turning), making it possible to avoid so-called oversteer or understeer.

[0050] Furthermore, when the pitch angle exceeds a certain value (No in step S1300), the controller 50 changes the pitch rate ω to a second corrected pitch rate ω _c2 * In particular, the second corrected pitch rate ω _c2 * The absolute value of is set to a smaller value as the gradient angle increases.

[0051] As a result, when the vehicle 100 is traveling on an uphill road, the pitch displacement can be suppressed according to the magnitude of the gradient angle (the degree of inclination of the uphill road), thereby preventing the vehicle 100 from moving forward or backward unintentionally due to the gradient.

[0052] In addition, when the friction (road surface μ) of the road is less than a certain value (No in step S1400), the controller 50 sets the pitch rate ω to a second corrected pitch rate ω _c2 * In particular, the second corrected pitch rate ω _c2 * The absolute value of is set to a smaller value as the road surface μ is smaller.

[0053] As a result, in a scene where the vehicle 100 is traveling on a slippery road surface, the pitch displacement is suppressed according to the smallness of the road surface μ (slipperiness), and slip of the vehicle 100 can be prevented.

[0054] FIG. 8 shows the second corrected pitch rate ω _c2 * 8 is a time chart showing an example of a control result when the first corrected pitch rate ω _c1 * and the basic pitch rate ω _b * The change over time of the pitch angle θ when the above formula is applied is partially shown by the dashed and dotted lines, respectively.

[0055] As shown in the figure, according to the control of this embodiment, when it is detected that the steering angle of the vehicle 100 has reached a certain value or more (time t3), the second correction pitch rate ω is set as the target value of the pitch rate ω in the pitch rate adjustment process according to an increase in the longitudinal acceleration a during the detection. _c2 * This sets the first corrected pitch rate ω _c1 * Similarly, when it is detected that the gradient angle has reached a certain value or more (time t4), the second corrected pitch rate ω _c2 * is set, and the control amount of the pitch angle θ is reduced. Furthermore, when it is detected that the road surface μ is less than a certain value (time t5), the second correction pitch rate ω _c2 * is set, and the control amount of the pitch angle θ is reduced.

[0056] The effects of the configuration of this embodiment described above will now be described in more detail.

[0057] In this embodiment, the vehicle 100 is controlled so that the pitch angle θ of the vehicle 100 behaves as desired by allocating a driving force (F f ,F r In this driving force control method, a required acceleration a for the vehicle 100 is controlled. fr Based on this, the required acceleration a fr Then, in the pitch rate adjustment process, the pitch rate ω is adjusted so as to generate a pitch displacement in a direction that cancels the longitudinal acceleration a corresponding to the front wheel motor 10f (front wheel driving force F f ) and the driving force of the rear wheel motor 10r (rear wheel driving force F r ) in different directions to adjust the pitch rate ω.

[0058] This adjusts the front wheel drive force F to achieve the adjusted pitch rate ω. f and rear wheel drive force F r By controlling the positive / negative relationship between the two, it is possible to suppress the inertial force in the longitudinal direction acting on the occupant due to acceleration / deceleration in the longitudinal direction, and to suppress the shaking of the occupant's head in the pitch direction. Therefore, a control logic for driving force distribution that can suppress car sickness in the occupant is realized without using a complex mechanical structure.

[0059] In particular, in this embodiment, the pitch rate adjustment process is performed based on the required acceleration a fr This is executed after a command to change is issued (after time t1 in FIG. 6 or FIG. 7) and before the timing (time t2) when the longitudinal acceleration a actually changes.

[0060] This allows the occupants of the vehicle 100 to recognize the change in pitch angle θ prior to the actual change in the longitudinal acceleration a, thereby making them aware that a change in the longitudinal acceleration a will occur. This allows the occupants to be given an opportunity to prepare in advance for the change in the longitudinal acceleration a, thereby reducing the impact of the change in the longitudinal acceleration a on the occupants.

[0061] In particular, in the pitch rate adjustment process, when the longitudinal acceleration a is positive (when the vehicle 100 is accelerating), the rear wheel driving force F r By setting the pitch rate ω to a negative value, when the longitudinal acceleration a is negative (when the vehicle 100 is decelerating), the front wheel drive force F f By setting the pitch rate ω to a negative value, the pitch rate ω becomes a positive value. For convenience, this control logic is also referred to as the "first pitch control" below.

[0062] This realizes a specific control mode for suitably decreasing or increasing the pitch angle θ in accordance with the longitudinal acceleration a for the vehicle 100 having a structure in which the anti-dive angle φ is positive.

[0063] In addition, in the pitch rate adjustment process, when the longitudinal acceleration a is positive (when the vehicle 100 is accelerating), the front wheel drive force F f By setting the pitch rate ω to a negative value, when the longitudinal acceleration a is negative (when the vehicle 100 is decelerating), the rear wheel driving force F r By setting the pitch rate ω to a negative value, the pitch rate ω becomes a positive value. For convenience, this control logic is also referred to as the "second pitch control" below.

[0064] This realizes a specific control mode for suitably decreasing or increasing the pitch angle θ in accordance with the longitudinal acceleration a for the vehicle 100 having a structure in which the anti-dive angle φ is negative.

[0065] Furthermore, in the pitch rate adjustment process, when the anti-dive angle φ of the front suspension of the vehicle 100 is positive, if the longitudinal acceleration a is positive, the rear wheel driving force F rBy setting the pitch rate ω to a negative value, when the longitudinal acceleration a is negative, the front wheel driving force F f By setting the anti-dive angle φ of the suspension on the front side of the vehicle 100 to a negative value, the pitch rate ω is made a positive value. On the other hand, when the anti-dive angle φ of the suspension on the front side of the vehicle 100 is negative, if the longitudinal acceleration a is positive, the front wheel driving force F f By setting the pitch rate ω to a negative value, when the longitudinal acceleration a is negative, the rear wheel driving force F r By setting ω to negative, the pitch rate ω becomes positive.

[0066] This realizes a specific control mode for achieving a suitable decrease or increase in the pitch angle θ in accordance with the longitudinal acceleration a, regardless of whether the anti-dive angle φ of the vehicle 100 is positive or negative. In other words, it is possible to realize a general-purpose control logic for the pitch angle θ that can be used for both vehicles 100 with a positive anti-dive angle φ and vehicles 100 with a negative anti-dive angle φ.

[0067] In this embodiment, the absolute value of the pitch rate ω is made smaller as the steering angle of the vehicle 100 increases, as the gradient angle of the vehicle 100 increases, and / or as the friction of the road on which the vehicle 100 runs decreases.

[0068] As a result, even under the pitch rate adjustment process, the behavior of the pitch angle θ is determined in accordance with the running environment of the vehicle 100, taking into account the vehicle characteristics. _b * This can prevent the occurrence of a situation in which the behavior of the target object deviates excessively from that of the target object.

[0069] In addition, when the vehicle 100 is operating by automatic driving, the pitch rate adjustment process is executed, and when the vehicle 100 is operating by manual driving operation, the pitch rate ω is adjusted to a predetermined basic pitch rate ω _b * (step S1700). Then, the basic pitch rate ω _b * The required acceleration a for the vehicle 100 fr The basic driving force distribution (basic distribution ratio κ) is determined from the viewpoint of obtaining the desired vehicle characteristics based on the b) shall be determined accordingly.

[0070] This makes it possible to realize control of the pitch angle θ that can suppress shaking of the passenger's head in the pitch direction during autonomous driving. In particular, during autonomous driving, the required acceleration a fr The change command of the pitch angle θ is not directly linked to the driver's operation (such as operation on the accelerator pedal). For this reason, it is assumed that it is difficult for the passenger to predict the change in the longitudinal acceleration a during autonomous driving. Therefore, only in this case, the pitch angle θ is set to the basic pitch angle θ _b * By executing the pitch rate adjustment process of changing the pitch rate ω to ω, it is possible to suitably suppress the shaking of the body of the occupant caused by a change in the longitudinal acceleration a that is unexpected for the occupant. On the other hand, during manual driving operation in which the occupant can easily predict the change in the longitudinal acceleration a, the pitch rate ω can be controlled after more appropriately predicting the change in the longitudinal acceleration a. On the other hand, in a scene in which the change in the longitudinal acceleration a is difficult to predict, the behavior of the vehicle 100 can be stabilized by executing the control of the pitch rate ω that places importance on the vehicle characteristics.

[0071] Furthermore, in this embodiment, a controller 50 is provided as a driving force control device for executing the above driving force control method.

[0072] In particular, the controller 50 controls the distribution of driving force (F f ,F r The controller 50 functions as a driving force control device that controls the required acceleration a fr Based on this, the required acceleration a fr The pitch rate adjustment unit (step S1500 or step S1600) adjusts the pitch rate ω so as to generate a pitch displacement in a direction that cancels the longitudinal acceleration a corresponding to the front wheel motor 10f. f ) and the driving force of the rear wheel motor 10r (rear wheel driving force Fr ) in different directions to adjust the pitch rate ω.

[0073] This realizes a control device configuration suitable for executing the above-described driving force control method.

[0074] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments.

[0075] For example, in the above embodiment, an example has been described in which the controller 50 (pitch rate adjustment unit 56) is configured to be able to selectively execute the first pitch control and the second pitch control by referring to the antidive angle φ determined from the structure of the vehicle 100. However, the present invention is not limited to this, and the controller 50 may be configured to be able to execute only one of the first pitch control and the second pitch control. In this way, by using the controller 50 that implements control logic for the pitch angle θ appropriate for the positive or negative antidive angle φ of the vehicle 100 that is known in advance, it is possible to obtain the effects substantially expected in the driving force control method of this embodiment, and also to simplify the program implemented in the controller 50. [Explanation of symbols]

[0076] 10 Drive motor 10f Front wheel motor 10r rear wheel motor 11f Front wheel 11r rear wheel 12f Front wheel inverter 12r rear wheel inverter 50 Controller 52 Total required driving force calculation unit 53 Basic driving force distribution section 55 Required jerk calculation unit 56 Pitch rate adjustment unit 100 vehicles

Claims

1. 1. A driving force control method for controlling a driving force distribution to a first driving source connected to front wheels and a second driving source connected to rear wheels so that a pitch angle of a vehicle behaves as desired, comprising: execute a pitch rate adjustment process for adjusting a pitch rate based on a required acceleration for the vehicle so as to generate a pitch displacement in a direction that cancels the longitudinal acceleration corresponding to the required acceleration; the pitch rate adjustment process adjusts the pitch rate by controlling the drive force distribution so that the drive force of the first drive source and the drive force of the second drive source are different in positive and negative from each other; The pitch rate adjustment process is executed after a command to change the required acceleration is issued and before the longitudinal acceleration actually changes. Driving force control method.

2. 2. A driving force control method according to claim 1, In the pitch rate adjustment process, When the longitudinal acceleration is positive, the driving force of the second driving source is set to negative, thereby making the pitch rate a negative value; when the longitudinal acceleration is negative, the driving force of the first driving source is set to a negative value, thereby making the pitch rate a positive value. Driving force control method.

3. 2. A driving force control method according to claim 1, In the pitch rate adjustment process, When the anti-dive angle of the suspension on the front side of the vehicle is positive, When the longitudinal acceleration is positive, the driving force of the second driving source is set to negative, thereby making the pitch rate a negative value; When the longitudinal acceleration is negative, the driving force of the first driving source is set to a negative value, thereby making the pitch rate a positive value; If the anti-dive angle is negative, When the longitudinal acceleration is positive, the driving force of the first driving source is set to negative, thereby making the pitch rate a negative value; when the longitudinal acceleration is negative, the driving force of the second driving source is set to a negative value, thereby making the pitch rate a positive value. Driving force control method.

4. A driving force control method according to any one of claims 1 to 3, Furthermore, the greater the steering angle of the vehicle, the smaller the absolute value of the pitch rate. Driving force control method.

5. A driving force control method according to any one of claims 1 to 4, Furthermore, the greater the gradient angle of the road on which the vehicle is traveling, the smaller the absolute value of the pitch rate is set. Driving force control method.

6. A driving force control method according to any one of claims 1 to 5, Furthermore, the absolute value of the pitch rate is made smaller as the friction of the road on which the vehicle runs is smaller. Driving force control method.

7. A driving force control method according to any one of claims 1 to 6, executing the pitch rate adjustment process when the vehicle is operating in an autonomous driving mode; setting the pitch rate to a predetermined base pitch rate when the vehicle is being manually operated; determining the basic pitch rate in accordance with a basic driving force distribution determined from the viewpoint of obtaining a desired vehicle characteristic based on a required acceleration for the vehicle; Driving force control method.

8. A driving force control device that controls a driving force distribution to a first driving source connected to a front wheel and a second driving source connected to a rear wheel so that a pitch angle of a vehicle behaves as desired, comprising: a pitch rate adjustment unit that adjusts a pitch rate based on a required acceleration for the vehicle so as to generate a pitch displacement in a direction that cancels out a longitudinal acceleration corresponding to the required acceleration, The pitch rate adjustment unit is adjusting the pitch rate by controlling the drive force distribution so that the drive force of the first drive source and the drive force of the second drive source are different in sign from each other; The pitch rate adjustment is performed after a command for changing the required acceleration is issued and before the longitudinal acceleration actually changes. Driving force control device.

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