JP4904972B2 - Slip suppression control device - Google Patents

Description

  The present invention relates to a slip suppression control device for recovering a slip when a slip occurs on a drive wheel of a vehicle.

  When a drive wheel of a vehicle such as a passenger car or a truck slips, the behavior of the vehicle becomes unstable, or the propulsion efficiency is lowered because the power generated by the power generation source cannot be effectively converted into the drive power. For this reason, when slip occurs in the drive wheel, it is necessary to quickly recover the grip of the drive wheel. Patent Document 1 discloses a slip control device that temporarily applies a predetermined braking torque to a drive wheel in which slip occurs regardless of the slip value of the drive wheel at the beginning of the start of slip control of the drive wheel. It is disclosed.

JP-A-2-38173

  However, since the technique disclosed in Patent Document 1 gives a predetermined braking torque regardless of the slip value in the initial stage of slip control, slip suppression becomes insufficient or braking of the drive wheels becomes excessive. Therefore, there is a possibility that a desired driving torque cannot be generated.

  Therefore, the present invention has been made in view of the above, and is capable of quickly recovering a slip generated on a drive wheel in accordance with a slip state of the drive wheel and driving the drive wheel with an appropriate driving force. An object is to provide a suppression control device.

In order to solve the above-described problems and achieve the object, a slip suppression control device according to the present invention suppresses slipping of a drive wheel that travels a vehicle, the drive torque of the drive wheel, Based on the speed and the speed of the vehicle, a history of a relationship between a slip parameter that is a measure of the slip state of the drive wheel and a friction parameter that is a measure of the friction between the drive wheel and the road surface is created and stored in the storage means Drive torque for determining the drive torque of the drive wheels based on a history creation unit to be stored, the maximum value of the friction parameter and the slip parameter obtained from the history, and the current friction parameter obtained from the history seen including a calculation unit, wherein the slip parameter obtained from the history, it and the friction parameters obtained from the history up The driving torque calculation unit determines a first slip suppression torque based on the maximum value of the friction parameter obtained from the history and the current friction parameter obtained from the history. In addition, the vehicle speed at the current time, the speed of the driving wheel at the current time, the slip parameter when the friction parameter obtained from the history is maximized, and the driving wheel returns from the slip state to the grip state. A second slip suppression torque is determined based on the set time, and a value obtained by subtracting the first slip suppression torque and the second slip suppression torque from the drive torque of the drive wheel at the present time is determined as the drive. The driving torque of the wheel is used.

  With this configuration, the slip suppression control device can recover the slip state of the drive wheel to a desired state in consideration of the current friction parameter obtained from the history. As a result, the slip generated in the drive wheel can be quickly recovered according to the slip state of the drive wheel, and the drive wheel can be driven with an appropriate driving force.

  The slip suppression control device according to the present invention is characterized in that, in the slip suppression control device, the drive torque calculation unit changes the set time according to the magnitude of the slip parameter.

  In the slip suppression control device according to the present invention, when the vehicle is inclined in the slip suppression control device, or when the friction parameter does not have a peak characteristic with respect to the change of the slip parameter, The set time is changed according to the magnitude of the slip parameter.

  The slip suppression control apparatus according to the present invention is characterized in that, in the slip suppression control apparatus, the set time is shortened as the slip parameter increases.

  In the slip suppression control device according to the next aspect of the present invention, in the slip suppression control device, the drive torque calculation unit includes an acceleration of the drive wheel necessary for the drive wheel to return from the slip state to the grip state in the set time. And the friction parameter is corrected based on the actual acceleration of the drive wheel.

  According to the present invention, the slip generated on the drive wheel can be quickly recovered according to the slip state of the drive wheel, and the drive wheel can be driven with an appropriate driving force.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the best mode for carrying out the invention (hereinafter referred to as an embodiment). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, or those that are substantially the same, and those that are included in a so-called equivalent range.

  In the following description, a case where the present invention is applied to a vehicle using an electric motor as a power generation source, for example, a so-called electric vehicle or FCV (Fuel Cell Vehicle) will be described. It is sufficient to provide a power generation source that can control the driving force. If it is such a vehicle, this invention is applicable also to what is called a hybrid vehicle which uses an electric motor and an internal combustion engine as a power generation source, and the vehicle which uses an internal combustion engine for a power generation source. In the present invention, since the slip of the drive wheel is suppressed by adjusting the torque of the power generation source, the power generation source provided in the vehicle can easily know the torque being output, such as an electric motor. In addition, it is preferable that the output torque can be changed quickly.

  In the following, the slip suppression control refers to control that suppresses slips that are not allowed to occur in the drive wheels included in the vehicle to slips within the allowable range. For example, when the road surface reaction force between the driving wheel and the road surface has a maximum value with respect to the change in the slip ratio, if the slip ratio of the driving wheel exceeds the slip ratio at the maximum road surface reaction force, the slip of the driving wheel Is not acceptable. In this case, the slip suppression control is a control for suppressing the slip ratio of the drive wheel to the slip ratio at the maximum road reaction force when the slip ratio of the drive wheel provided in the vehicle exceeds the slip ratio at the maximum road reaction force. Become.

(Embodiment 1)
In this embodiment, based on the driving torque of the driving wheel of the vehicle, the speed of the driving wheel, and the speed of the vehicle, the slip parameter as a measure of the slip state of the driving wheel and the friction between the driving wheel and the road surface are measured. A history of the relationship with a friction parameter as a scale is created, and based on the maximum value of the friction parameter obtained from the history and the slip parameter, and the current friction parameter obtained from the history, the driving wheel It is characterized in that the driving torque is determined. Here, the friction parameter is a parameter serving as a scale indicating the magnitude of the friction between the driving wheel and the road surface, such as the road surface reaction force, the friction coefficient between the driving wheel and the road surface, and the like. The slip parameter is a parameter that serves as a scale indicating the slip state (slip magnitude) between the drive wheel and the road surface, such as the slip ratio and slip amount.

  FIG. 1 is a schematic diagram illustrating a configuration of a vehicle including a traveling device according to the first embodiment. In the following description, the direction in which the vehicle 1 moves forward (the direction of the arrow X in FIG. 1) is the front, and the direction in which the vehicle 1 moves backward, that is, the direction opposite to the direction in which the vehicle 1 moves forward is the rear. The left / right distinction is based on the direction in which the vehicle 1 moves forward. That is, “left” refers to the left side in the direction in which the vehicle 1 moves forward, and “right” refers to the right side in the direction in which the vehicle 1 moves forward.

  The vehicle 1 according to the first embodiment includes a traveling device 100 that uses only an electric motor as a power generation source. The traveling device 100 includes a left front motor 10fl, a right front motor 10fr, a left rear motor 10rl, and a right rear motor 10rr that are power generation sources. In this embodiment, the left front motor 10fl drives the left front wheel 2fl, the right front motor 10fr drives the right front wheel 2fr, the left rear motor 10rl drives the left rear wheel 2rl, and the right rear motor 10rr is on the right side. The rear wheel 2rr is driven.

  As described above, in the traveling device 100, the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl, and the right rear wheel 2rr are driven by different electric motors. Thus, in the vehicle 1, all the wheels are drive wheels. That is, the drive wheels of the vehicle 1 are the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl, and the right rear wheel 2rr. The left front wheel 2fl and the right front wheel 2fr are drive wheels of the vehicle 1 and also function as steering wheels that are steered by the handle 4 to change the traveling direction of the vehicle 1.

  In the traveling device 100, as described above, the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl, and the right rear wheel 2rr are directly driven by different electric motors. The left front motor 10fl, the right front motor 10fr, the left rear motor 10rl and the right rear motor 10rr are disposed in the wheels of the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl and the right rear wheel 2rr. It has a so-called in-wheel configuration.

  A speed reduction mechanism is provided between the motor and the wheel to reduce the rotational speed of the left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr, and the left front wheel 2fl and the right front wheel 2fr. The left rear wheel 2rl and the right rear wheel 2rr may be transmitted. In general, when the electric motor is downsized, the torque decreases, but the torque of the electric motor can be increased by providing a speed reduction mechanism. As a result, the left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr can be reduced in size.

  The left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr are controlled by an ECU (Electronic Control Unit) 50, and the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl, the right rear wheel The driving force of the wheel 2rr is adjusted. In this embodiment, the total driving force F_all of the traveling device 100, the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl, and the right rear wheel 2rr according to the opening of the accelerator 5 detected by the accelerator opening sensor 41. The driving force is controlled.

  In the slip suppression control according to this embodiment, the driving force of the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl, and the right rear wheel 2rr is changed by the slip suppression control device 30 incorporated in the ECU 50. That is, in the slip suppression control according to this embodiment, the slip suppression control device 30 exhibits a function as a driving force changing unit that changes the driving force of each driving wheel provided in the vehicle 1. In this embodiment, the driving force of each of the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl, and the right rear wheel 2rr can be independently controlled by the above-described configuration. Thus, when the slip suppression control according to this embodiment is executed, the slips of the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl, and the right rear wheel 2rr can be individually controlled.

  The left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr are rotated by the left front resolver 40fl, the right front resolver 40fr, the left rear resolver 40rl, and the right rear resolver 40rr. Is detected. The outputs of the left front resolver 40fl, the right front resolver 40fr, the left rear resolver 40rl, and the right rear resolver 40rr are captured by the ECU 50, and the left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear side Used to control the electric motor 10rr.

  The left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr are connected to the inverter 6. An in-vehicle power source 7 such as a nickel-hydrogen battery, a lead storage battery, or a fuel cell (FC) is connected to the inverter 6, and the left front motor 10 fl and the right front side are connected via the inverter 6 as necessary. The electric power is supplied to the electric motor 10fr, the left rear electric motor 10rl, and the right rear electric motor 10rr. These outputs are controlled by controlling the inverter 6 according to a command from the ECU 50. In this embodiment, one motor is controlled by one inverter. In order to control the left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr, the inverter 6 includes four inverters corresponding to the respective motors.

  When the left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr are used as power generation sources of the traveling device 100, the electric power of the in-vehicle power supply 7 is supplied via the inverter 6. For example, when the vehicle 1 is decelerated, the left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr function as a generator to perform regenerative power generation, thereby reducing the kinetic energy of the vehicle 1. It is converted into electrical energy, collected, and stored in the in-vehicle power source 7. This is realized by the ECU 50 controlling the inverter 6 based on a signal such as a brake signal or an accelerator off. In addition, also when performing the slip suppression control according to this embodiment, regenerative power generation of the left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr is executed as necessary. Next, the state when the drive wheel slips will be described.

  FIG. 2 is an explanatory diagram showing temporal changes in drive torque, road surface reaction force, drive wheel speed, vehicle speed, and slip rate when the drive wheels of the vehicle slip. FIG. 3 is a conceptual diagram illustrating driving torque, road surface reaction force, and the like. In the following, for convenience of explanation, the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl, and the right rear wheel 2rr are referred to as drive wheels 2 without distinction as necessary.

  While the vehicle 1 is traveling, for example, when the torque (drive torque) T of the drive wheel 2 increases (the upper stage in FIG. 2), the vehicle 1 starts to slip between the drive wheel 2 and the road surface GL ((1) in the middle stage in FIG. 2). Part shown by). When the drive wheel 2 starts to slip, the difference between the drive wheel speed (circumferential speed of the drive wheel 2) Vw and the vehicle speed (travel speed of the vehicle 1) V increases, and as a result, the slip ratio slip increases. Further, the road surface reaction force (force by which the road surface GL pushes the driving wheel 2) Ftrc also increases. Here, the drive wheel speed Vw is Vw = r × ω where the rotational angular speed of the drive wheel 2 is ω and the radius of the drive wheel 2 (distance from the rotation axis Zr to the outer periphery) is r (see FIG. 3). ).

Here, the road surface reaction force Ftrc can be obtained from equation (1), and the slip ratio slip can be obtained from equation (2).
Ftrc = (T × RD−Iv × a) / r (1)
slip = (Vw−V / Vw) (2)
Note that Iv is inertia of the drive system including inertia of the drive wheel 2, RD is a reduction ratio, and a is acceleration of the drive wheel 2 (drive wheel acceleration). For example, in the vehicle in this embodiment, the inertia of the drive system is an inertia of all structures related to power transmission existing between the rotor of the electric motor and the drive wheels 2.

While the drive wheel 2 is slipping, there is a place where the road surface reaction force becomes maximum (the portion indicated by (2) in the middle stage of FIG. 2). Let this time be t ₁ . At this time, the road surface reaction force is the maximum road surface reaction force Ftrc_max, and the slip rate is the maximum road surface reaction force slip rate slip_max.

When the maximum road surface reaction force Ftrc_max is exceeded (after t = t ₁ ), the drive wheel speed Vw increases rapidly in a short time, and the slip ratio slip also increases rapidly. When the slip rate slip exceeds the peak, the drive torque T is controlled to gradually recover the slip of the drive wheels 2 to the grip state (the portion indicated by (3) in the middle stage of FIG. 2). The portion indicated by (4) in the middle stage of FIG. 2 is in the middle of the recovery of the slip of the drive wheel 2 to the grip state, and the slip ratio slip approaches the slip ratio during grip traveling.

  In general, it is preferable that the driving wheel 2 is driven in a state where the maximum road surface reaction force slip rate slip_max, that is, the maximum road surface reaction force Ftrc_max is generated between the driving wheel 2 and the road surface GL. Therefore, when slip occurs in the drive wheel 2, it is preferable to return the slip ratio to the maximum road surface reaction force slip ratio slip_max as soon as possible.

  Here, when the driving torque T increases or when the driving torque T is constant but the driving wheel 2 shifts from the high μ road surface to the low μ road surface, the driving wheel 2 slips, and the slip ratio is maximized. When the road surface reaction force slip ratio slip_max is exceeded, the rotational speed of the drive wheel 2 increases with acceleration. As a result, the slip rate slip tends to rapidly shift to a higher slip rate. Therefore, in the slip control according to this embodiment, when the slip of the drive wheel 2 occurs, the slip ratio is returned to the maximum road surface reaction force slip ratio slip_max after canceling the acceleration of the drive wheel 2.

  FIG. 4 is a conceptual diagram showing the relationship between the road surface reaction force and the slip ratio. FIG. 4 is also a road surface reaction force-slip rate history map (Fs history map) used in the slip suppression control of the first embodiment. FIG. 5 is a conceptual diagram showing recovery of the drive wheel speed when slip occurs in the drive wheel.

  In this embodiment, when the slip of the drive wheel 2 occurs, the slip ratio is set to a certain value (so that the slip of the drive wheel 2 does not proceed more than the present by canceling the acceleration of the drive wheel 2. slip_p), that is, the road surface reaction force is kept at a certain constant value (Ftrc_p), and the increase in the slip rate slip is suppressed. In this embodiment, the first slip suppression torque T1 is subtracted from the current drive torque T_p in order to cancel the acceleration of the drive wheel 2.

The first slip suppression torque T1 is a torque for suppressing an increase in the slip ratio and maintaining a constant slip ratio, and is represented by Expression (3).
T1 = a × Iv = (Ftrc_max−Ftrc_p) × r / RD (3)
Here, r is the radius of the drive wheel 2. Ftrc_max in equation (3) is obtained from the Fs history map 60 of FIG. 4, and Ftrc_p gives the slip rate slip_p obtained from the current vehicle speed V and the current drive wheel speed Vw to the Fs history map 60. Ask.

When the driving torque obtained by subtracting the first slip suppression torque T1 from the current driving torque T_p is applied to the driving wheel 2, the driving wheel 2 is slipped at a certain slip ratio (slip_p in this embodiment). That is, the slip ratio of the drive wheel 2 stops at slip_p, and does not increase or decrease. Therefore, in this embodiment, in addition to the first slip suppression torque T1, the second slip suppression torque is further subtracted from the current drive torque T_p to restore the drive wheel 2 from the slip state to the grip state. When the drive wheel 2 is restored to the grip state, the slip rate of the drive wheel 2 is set to the maximum road surface reaction force slip rate slip_max. As a result, the vehicle 1 can be driven by making the most effective use of the grip force of the drive wheels 2. Here, the second slip suppression torque T2 is expressed by Expression (4).
T2 = (Vw−V / (1−slip_max)) × 1000/3600 / Δt / π / r × π × RD × Iv (4)
Here, the maximum road surface reaction force slip ratio slip_max is obtained from the Fs history map 60 of FIG. From equation (4), the second slip suppression torque T2 is a torque required to recover the slip of the drive wheel 2 to the grip state in the set time Δt. The set time Δt is a time until the slip rate of the drive wheel 2 reaches the maximum road surface reaction force slip rate slip_max from the slip rate slip_p at the current drive torque T_p. In addition, Vw and V in Formula (4) are values at the present time, and when Vw and V change during the slip suppression control, the changed values are used.

  Here, slip_max is a value for driving the drive wheel 2 so that the slip rate of the drive wheel 2 becomes the maximum road surface reaction force slip rate, that is, the maximum road surface reaction force Ftrc_max. In Formula (4), if a different value is used instead of slip_max, the drive wheel 2 is driven with the slip ratio of that value. For example, if a value not less than 0 and less than slip_max is set instead of slip_max, the drive wheels 2 can be driven with a slip ratio smaller than the maximum slip ratio. Thus, for example, when it is not necessary to drive the vehicle 1 at the maximum slip rate depending on the driving conditions (for example, fuel saving mode), or when the vehicle 1 is driven at the maximum slip rate according to road conditions (for example, a road surface that is extremely slippery) When the suppression control may cause hunting, an appropriate slip ratio can be set.

  The first slip suppression torque T1 obtained from the equation (3) and the second slip suppression torque T2 obtained from the equation (4) are calculated from the current drive torque T_p in a state where the drive wheel 2 is slipping. The subtracted torque is set as a target drive torque T_o for suppressing the slip of the drive wheel 2. That is, T_o = T_p− (T1 + T2). Here, when T1 + T2 is the target slip suppression torque T_trc, T_o = T_p−T_trc.

  In this embodiment, the second slip suppression torque T2 is set as shown in Expression (4), and the grip state is restored in the set time Δt. Thereby, it is possible to suppress hunting of the driving wheel speed Vw when the driving wheel 2 recovers to the grip state (the chain line in FIG. 5). And as shown to the continuous line of FIG. 5, the driving wheel 2 can be rapidly recovered to a grip state. Next, the slip suppression control device 30 according to this embodiment will be described.

  FIG. 6 is an explanatory diagram illustrating a configuration example of the slip suppression control device according to the first embodiment. As shown in FIG. 6, the slip suppression control device 30 is configured to be incorporated in the ECU 50. The ECU 50 includes a CPU (Central Processing Unit) 50p, a storage unit 50m, an input port 55 and an output port 56, and an input interface 57 and an output interface 58.

  In addition, separately from ECU50, the slip suppression control apparatus 30 which concerns on this embodiment may be prepared, and this may be connected to ECU50. And in implement | achieving the slip suppression control which concerns on this embodiment, you may comprise so that the said slip suppression control apparatus 30 can utilize the control function with respect to the traveling apparatus 100 etc. with which ECU50 is provided.

  The slip suppression control device 30 includes a history creation unit 31, an operation condition determination unit 32, and a drive torque calculation unit 33. These are the parts that execute the slip suppression control according to this embodiment. In this embodiment, the slip suppression control device 30 is configured as a part of the CPU 50p configuring the ECU 50.

The history creation unit 31, the operation condition determination unit 32, and the drive torque calculation unit 33 of the slip suppression control device 30 are connected via a bus 54 ₁ , a bus 54 ₂ , an input port 55, and an output port 56. As a result, the history creation unit 31, the operating condition determination unit 32, and the drive torque calculation unit 33 constituting the slip suppression control device 30 can exchange control data with each other or issue commands to one side. Composed.

Further, a slip suppression control device 30 provided in the CPU 50p, and the storage unit 50m, are connected via a bus 54 _3. Thereby, the slip suppression control device 30 can acquire the operation control data of the traveling device 100 included in the ECU 50 and can use it. Moreover, the slip suppression control device 30 can interrupt the slip suppression control according to this embodiment into an operation control routine that the ECU 50 has in advance.

  An input interface 57 is connected to the input port 55. The input interface 57 includes a left front resolver 40fl, a right front resolver 40fr, a left rear resolver 40rl, a right rear resolver 40rr, an accelerator opening sensor 41, a steering angle sensor 42, a vehicle speed sensor 43, a longitudinal acceleration sensor 44, Sensors for acquiring information necessary for operation control of the traveling device 100, such as the lateral acceleration sensor 45, are connected.

  Signals output from these sensors are converted into signals that can be used by the CPU 50 p by the A / D converter 57 a and the digital input buffer 57 d in the input interface 57 and sent to the input port 55. Thereby, CPU50p can acquire the information required for the driving control of the traveling apparatus 100, and the slip suppression control which concerns on this embodiment.

An output interface 58 is connected to the output port 56. A control target necessary for slip suppression control is connected to the output interface 58. In this embodiment, the inverter 6 for controlling the left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr is a control target necessary for the slip suppression control according to this embodiment. . The output interface 58 includes control circuits 58 ₁ , 58 _{2 and the} like, and operates the control target based on a control signal calculated by the CPU 50p. With this configuration, the CPU 50p of the ECU 50 can control the driving force of the left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr based on output signals from the sensors. it can.

  The storage unit 50m stores a computer program including a processing procedure of slip suppression control according to this embodiment, a control map, a data map used for slip suppression control according to this embodiment, and the like. Here, the storage unit 50m can be configured by a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a flash memory, or a combination thereof.

  The computer program may be capable of realizing the processing procedure of the slip suppression control according to this embodiment in combination with the computer program already recorded in the CPU 50p. Further, the slip suppression control device 30 may implement the functions of the history creation unit 31, the operation condition determination unit 32, and the drive torque calculation unit 33 using dedicated hardware instead of the computer program. Good. Next, the slip suppression control according to this embodiment will be described. In the following description, please refer to FIGS.

  FIG. 7 is a flowchart illustrating a procedure for creating a history of road surface reaction force and slip rate in the slip suppression control according to the first embodiment. FIG. 8 is a flowchart illustrating a procedure for recovering a slip generated on a drive wheel to a grip state in the slip suppression control according to the first embodiment. In the slip suppression control in this embodiment, the history of the relationship between the road surface reaction force Ftrc of the drive wheel 2 and the slip rate slip is acquired between the grip state and the slip state, and the Fs history map 60 (see FIG. 4). ). And the control parameter at the time of recovering the slip of the driving wheel 2 to a grip state is set using the Fs log | history map 60. FIG.

  In the slip suppression control according to this embodiment, a history of the relationship between the road surface reaction force Ftrc and the slip rate slip is first acquired and stored as an Fs history map 60 (see FIG. 4). For this reason, the history creation unit 31 of the slip suppression control device 30 calculates the road surface reaction force Ftrc and the slip rate slip (step S101). The road surface reaction force Ftrc can be obtained from equation (1), and the slip ratio slip can be obtained from equation (2).

  Here, the driving torque T used when the road surface reaction force Ftrc is obtained can be obtained from a torque command value (current value) for each electric motor. Further, the driving wheel acceleration a can be obtained based on a change in the driving wheel speed Vw of each driving wheel detected from a resolver attached to each driving wheel. Further, the driving wheel speed Vw used when the slip ratio slip is obtained can be obtained from a resolver attached to each driving wheel, and the vehicle speed V can be obtained from the vehicle speed sensor 43.

  Next, the history creation unit 31 stores and stores the relationship between the road surface reaction force Ftrc and the slip rate slip obtained in step S101 in the storage unit 50m of the ECU 50, which is a history storage unit (step S102). The history creation unit 31 acquires a relationship between a plurality of road surface reaction forces Ftrc and a slip rate slip between the grip state and the slip state, and stores the relationship in the storage unit 50m, whereby the Fs history map shown in FIG. Get 60. The Fs history map 60 is stored in the storage unit 50m.

  When the Fs history map 60 is obtained, the history creation unit 31 determines the maximum road surface reaction force Ftrc_max and the maximum road surface reaction force slip rate slip_max from the Fs history map 60 (step S103). This can be determined by setting the peak value of the road surface reaction force Ftrc in the F-s history map 60 as the maximum road surface reaction force Ftrc_max and the slip rate at that time as the maximum road surface reaction force slip rate slip_max. In the slip suppression control described below, that is, the control for restoring the slip generated in the drive wheel 2 to the grip state, the control parameter is set using the Fs history map 60 obtained by the above procedure.

  In executing the slip suppression control, the operating condition determination unit 32 of the slip suppression control device 30 determines whether or not a slip has occurred in at least one drive wheel 2 while the vehicle 1 is traveling (step S201). For example, when the deviation between the vehicle speed V acquired from the vehicle speed sensor 43 and the drive wheel speed Vw exceeds a predetermined threshold, it can be determined that slip has occurred in the drive wheel. Further, when the slip ratio exceeds a predetermined threshold value, it may be determined that slip has occurred in the drive wheel.

  If no slip has occurred in any of the drive wheels 2 (step S201: No), the process returns to START, and the driving condition determination unit 32 monitors the driving state of the vehicle 1. When slip occurs in at least one drive wheel 2 (step S201: Yes), the drive torque calculation unit 33 of the slip suppression control device 30 uses the first slip suppression torque T1 and the second slip suppression torque T2 described above. Determine (step S202). The first slip suppression torque T1 can be determined from equation (3), and the second slip suppression torque T2 can be determined from equation (4). The set time Δt used when determining T2 is set in advance as a constant value.

  Here, the road surface reaction force Ftrc_p used when determining the first slip suppression torque T1 is obtained by giving the slip rate slip_p when determining T1 and T2 in the slip suppression control to the Fs history map 60. The road surface reaction force. Further, the slip ratio slip_p used when determining the second slip suppression torque T2 is a slip ratio when determining T1 and T2 by the slip suppression control.

  When T1 and T2 are determined (step S202), the drive torque calculator 33 determines a target slip suppression torque T_trc (= T1 + T2) (step S203). Then, the drive torque calculation unit 33 uses the determined target slip suppression torque T_trc and the current drive torque (that is, the drive torque in a state where the drive wheel 2 is slipping) Tp to generate a slip. A target drive torque T_o (= T_p−Ttrc) for driving the driven wheels is calculated (step S204).

  Then, the drive torque calculation unit 33 instructs the target drive torque T_o calculated in step S204 to the inverter 6 (step S205), and drives the drive wheel in which slip has occurred with the target drive torque T_o. As a result, the drive wheel 2 in which the slip is generated quickly recovers to the grip state, and the slip rate of the drive wheel 2 becomes the maximum road surface reaction force slip rate slip_max. As a result, the drive wheels 2 that have recovered from the slip can make the vehicle 1 travel by making the most effective use of the grip force.

  As described above, in this embodiment, a history of the relationship between the slip parameter that is a measure of the slip state of the drive wheel and the friction parameter that is a measure of the friction between the drive wheel and the road surface is created, and the friction obtained from the history is obtained. The drive torque of the drive wheel is determined based on the maximum value of the parameter, the slip parameter, and the current friction parameter obtained from the history. Thus, the slip state of the drive wheel is taken into consideration by the current friction parameter obtained from the history, and the friction between the drive wheel and the road surface can be restored to a desired state existing on the history. As a result, the slip generated in the drive wheel can be quickly recovered according to the slip state of the drive wheel, and the drive wheel can be driven with an appropriate driving force. The configuration of this embodiment can also be applied as appropriate in the following embodiments. Moreover, what is equipped with the structure disclosed by this embodiment and its modification has the effect | action and effect similar to this embodiment and its modification.

(Embodiment 2)
The second embodiment has substantially the same configuration as that of the first embodiment, but changes the set time Δt according to the slip parameter and makes the set time Δt constant according to the running state of the vehicle, or according to the slip parameter. The point of selecting whether to change is different. Other configurations are the same as those of the first embodiment. Note that the slip suppression control according to the second embodiment can be realized by the slip suppression control device 30 (see FIG. 6) according to the first embodiment. In the following description, please refer to FIGS.

  FIG. 9 is an explanatory diagram showing the relationship between the set time and the slip amount. FIG. 10 is a flowchart illustrating a procedure for recovering a slip generated on a drive wheel to a grip state in the slip suppression control according to the second embodiment. FIG. 11 is an explanatory diagram showing the relationship between the friction coefficient and the slip amount. FIG. 12 is a conceptual diagram showing recovery of driving wheel speed when slip occurs on the driving wheel.

  As shown in FIG. 9, in the first embodiment, regardless of the slip amount S (or slip ratio slip) of the driving wheel 2, that is, the magnitude of the slip parameter, the set time Δt (the slip ratio of the driving wheel 2 is equal to the current slip rate). The time from the slip rate slip_p to the maximum road surface reaction force slip rate slip_max at the driving torque T_p was constant (Δt = Δt_b). In this embodiment, the set time Δt is changed according to the slip amount S of the drive wheels 2, that is, the magnitude of the slip parameter. For example, as shown in FIG. 9, the set time Δt is shortened as the slip amount S increases. In this example, as the slip amount S increases, the set time Δt is changed from Δt_a (Δt_a> 0) to 0.

  Thereby, as shown by the solid line in FIG. 12, the grip of the drive wheel 2 can be recovered in a time earlier than the slip suppression control according to the first embodiment (dotted line in FIG. 12). Also, shock when the grip is restored can be reduced. Furthermore, since the set time Δt is reduced when the slip amount S of the drive wheel 2 is large, the behavior of the vehicle 1 can be quickly stabilized when the slip amount S is large and the behavior change of the vehicle 1 is large. .

  In the slip suppression control according to the second embodiment, as described below, whether the set time Δt is constant or the set time Δt is changed according to the magnitude of the slip parameter according to the traveling state of the vehicle 1. Select. In executing the slip suppression control according to the second embodiment, the operating condition determination unit 32 determines whether or not there is a peak in the relationship between the friction coefficient μ (that is, the friction parameter) and the slip amount S (that is, the slip parameter). (Step S301). As will be described later, instead of the relationship between the friction coefficient μ and the slip amount S, the relationship between the road surface reaction force Ftrc as a friction parameter and the slip ratio slip as a slip parameter may be used.

  Here, the case where the relationship between μ and S has a peak property refers to a case where the maximum value of μ with respect to S is obtained as shown by the curve A in FIG. For example, when traveling on a normal paved road surface, there is a peak in the relationship between μ and S. Further, the case where there is no peak in the relationship between μ and S refers to the case where there is no maximum value of μ with respect to S as shown by the curve B shown in FIG. For example, when traveling in deep snow, there is no peak in the relationship between μ and S.

  The relationship between the friction coefficient μ and the slip amount S can be considered by replacing it with the relationship between the road surface reaction force Ftrc and the slip rate slip. Therefore, whether or not the friction coefficient μ and the slip amount S have a peak property can be determined by whether or not the road surface reaction force Ftrc and the slip rate slip have a peak property. Whether or not the road surface reaction force Ftrc and the slip rate slip have a peak can be determined from the Fs history map 60 (see FIG. 4) created from the history of the road surface reaction force Ftrc and the slip rate slip. . For example, if the road surface reaction force Ftrc of the current F-s history map 60 has a maximum value with respect to the slip rate slip, it can be determined that the relationship between the friction coefficient μ and the slip amount S has a peak property. Further, if the road surface reaction force Ftrc of the current Fs history map 60 does not have a maximum value with respect to the slip rate slip, it can be determined that there is no peak in the relationship between the friction coefficient μ and the slip amount S.

  When the relationship between the friction coefficient μ and the slip amount S has a peak characteristic (step S301: Yes), the drive torque calculator 33 uses the set time Δt used when calculating the second slip suppression torque T2 as the slip amount. It changes according to S (step S305). That is, as shown in C1 in the set time map 61 shown in FIG. The slip amount S can be obtained from the difference (Vw−V) between the drive wheel speed Vw and the vehicle speed V. Further, as described above, a slip ratio slip may be used instead of the slip amount S. When calculating the second slip suppression torque T2, the drive torque calculator 33 calculates the slip amount S or slip rate slip at that time and gives it to the set time map 61 to obtain the corresponding set time Δt. The set time map 61 is stored in the storage unit 50m, for example.

  If the relationship between the friction coefficient μ and the slip amount S has no peak (step S301: No), is the set time Δt constant according to the running state of the vehicle (in this embodiment, the inclined state of the vehicle 1)? , Whether to change according to the slip amount S is selected. The driving condition determination unit 32 determines whether or not the vehicle 1 is turning based on information from the steering angle sensor 42 and the lateral acceleration sensor 45 (step S302). When the vehicle 1 is turning (step S302: Yes), the vehicle 1 is inclined by the roll. In this case, the drive torque calculator 33 changes the set time Δt used when calculating the second slip suppression torque T2 in accordance with the slip amount S (step S305).

  When the vehicle 1 is not turning (step S302: No), the driving condition determination unit 32 determines whether or not the road surface on which the vehicle 1 is traveling is canted (step S303). When the road surface on which the vehicle 1 is traveling is canted (step S303: Yes), the drive torque calculator 33 sets the set time Δt used when calculating the second slip suppression torque T2 to the slip amount S. It is changed accordingly (step S305).

  When there is no cant on the road surface on which the vehicle 1 is traveling (step S303: No), the driving condition determination unit 32 determines whether the road surface on which the vehicle 1 is traveling is a slope (step S304). . When the road surface on which the vehicle 1 is traveling is a slope (step S304: Yes), the drive torque calculation unit 33 sets the set time Δt used when calculating the second slip suppression torque T2 according to the slip amount S. (Step S305). When the road surface on which the vehicle 1 is traveling is not a slope (step S304: No), the set time Δt used when calculating the second slip suppression torque T2 is a constant value (Δt in this example) regardless of the slip amount S. = Δt_b) (step S306).

  As described above, in the second embodiment, the set time is changed according to the slip parameter. As a result, the drive wheel in the slip state can be quickly restored to the grip state, and shock when the drive wheel recovers the grip can be reduced. In addition, it is possible to realize slip suppression control according to the road surface condition and the wear state of the drive wheels. The set time may be set to 0 according to the slip state of the drive wheel. As a result, when the slip amount of the drive wheel is extremely large, the grip of the drive wheel can be quickly recovered, so that the behavior of the vehicle can be effectively prevented from becoming unstable.

  In addition, since it is selected whether to set the set time constant according to the running state of the vehicle or to change according to the slip parameter, if it is necessary to prioritize slip suppression, the set time is set according to the slip parameter. Thus, the slip of the drive wheel can be restored to the grip state at an early stage. The configuration of this embodiment can also be applied as appropriate in the following embodiments. Moreover, what is equipped with the structure disclosed by this embodiment and its modification has the effect | action and effect similar to this embodiment and its modification.

(Embodiment 3)
The third embodiment is substantially the same as the first embodiment except that the drive wheel acceleration required for the drive wheel to recover from the slip state to the grip state in the set time Δt and the actual acceleration of the drive wheel at the present time are described. The difference is that the road surface reaction force is corrected. Other configurations are the same as those of the first embodiment.

FIG. 13 is a conceptual diagram illustrating the correction of the road surface reaction force in the slip suppression control according to the third embodiment. The relationship between the road surface reaction force Ftrc and the slip rate slip at the present time is represented by F-s_1. The driving wheel acceleration A_g required when the driving wheel 2 recovers from the slip state to the grip state at the set time Δt is expressed by Expression (5). A_g is an estimated value.
A_g = −slip / (1-slip) × V × 1000/3600 / Δt / π / r × π × RD (5)

When the actual acceleration of the driving wheel is A_r, the road surface reaction force correction value (corrected road surface reaction force) ΔFtrc is expressed by Expression (6).
ΔFtrc = | A_r−A_g | × (It + Iv) × RD / r (6)

  When A_g> A_r, the road surface reaction force obtained from F-s_1 is lower than the actual road surface reaction force. In this case, the drive torque calculation unit 33 is a value obtained by adding the corrected road surface reaction force ΔFtrc obtained from the equation (6) to F−s_1 in a region where the slip rate is larger than the maximum road surface reaction force slip rate slip_max. The first slip suppression torque T1, the second slip suppression torque T2, and the target slip suppression torque T_trc are determined using F-s_2 obtained based on the above. Here, F−s_2 = F−s_1 × (Ftrc_max1 + ΔFtrc) / Ftrc_max1. The maximum road surface reaction force Ftrc_max2 at this time, that is, F-s_2 in slip_max is Fts_max1 × (Ftrc_max1 + ΔFtrc) / Ftrc_max1 because Fss = 1 = Ftrc_max1.

  When A_g <A_r, the road surface reaction force obtained from F-s_1 is higher than the actual road surface reaction force. In this case, the drive torque calculation unit 33 subtracts the corrected road surface reaction force ΔFtrc obtained using the equation (6) from F−s_1 in a region where the slip ratio is larger than the maximum road surface reaction force slip ratio slip_max. The first slip suppression torque T1, the second slip suppression torque T2, and the target slip suppression torque T_trc are determined using Fs_3 obtained based on the obtained value. Here, F−s — 3 = F−s — 1 × (Ftrc_max1 + ΔFtrc) / Ftrc_max1. At this time, the maximum road surface reaction force Ftrc_max3, that is, F-s_3 in the slip_max is Fts_max1 × (Ftrc_max1−ΔFtrc) / Ftrc_max1 because Fs_1 = Ftrc_max1.

  Errors due to delays due to communication and low rigidity such as drive shafts existing in the drive system may occur in the road surface reaction force and slip rate, but if the road surface reaction force is corrected by the above procedure, The error can be reduced. As a result, when slip occurs in the drive wheel 2, it is possible to recover the grip state more quickly and reliably. Moreover, the shock at the time of returning to a grip state can also be reduced.

  As described above, in this embodiment, the road surface reaction force (friction parameter) is corrected based on the driving wheel acceleration for recovering the driving wheel from the slip state to the grip state in the set time and the actual driving wheel acceleration at the present time. . This improves the accuracy of the slip suppression control. In addition, what is equipped with the structure disclosed by this embodiment and its modification has the effect | action and effect similar to this embodiment and its modification.

  As described above, the slip suppression control device according to the present invention is useful for suppressing the slip of the drive wheel, and in particular, the slip generated on the drive wheel is quickly recovered according to the slip state of the drive wheel. Suitable for that.

It is the schematic which shows the structure of a vehicle provided with the traveling apparatus which concerns on Embodiment 1. FIG. It is explanatory drawing which shows the time change of the driving torque, road surface reaction force, driving wheel speed, vehicle speed, and slip ratio when the driving wheel of a vehicle slips. It is a conceptual diagram explaining a driving torque, a road surface reaction force, etc. It is a conceptual diagram which shows the relationship between a road surface reaction force and a slip ratio. It is a conceptual diagram which shows recovery | restoration of the driving wheel speed when a slip generate | occur | produces in a driving wheel. It is explanatory drawing which shows the structural example of the slip suppression control apparatus which concerns on Embodiment 1. FIG. 5 is a flowchart illustrating a procedure for creating a history of road surface reaction force and slip ratio in the slip suppression control according to the first embodiment. 5 is a flowchart illustrating a procedure for recovering a slip generated on a drive wheel to a grip state in the slip suppression control according to the first embodiment. It is explanatory drawing which shows the relationship between setting time and slip amount. 6 is a flowchart illustrating a procedure for recovering a slip generated on a drive wheel to a grip state in the slip suppression control according to the second embodiment. It is explanatory drawing which shows the relationship between a friction coefficient and slip amount. It is a conceptual diagram which shows recovery | restoration of the driving wheel speed when a slip generate | occur | produces in a driving wheel. It is a conceptual diagram explaining correction | amendment of the road surface reaction force in the slip suppression control which concerns on Embodiment 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Drive wheel 2fl Left front wheel 2fr Right front wheel 2rl Left rear wheel 2rr Right rear wheel 4 Handle 5 Accelerator 6 In-vehicle power supply 10fl Left front motor 10fr Right front motor 10rl Left rear motor 10rr Right rear motor 30 Slip suppression control 30 Device 31 History creation unit 32 Operating condition determination unit 33 Driving torque calculation unit 40fl Left front resolver 40fr Right front resolver 40rl Left rear resolver 40rr Right rear resolver 41 Accelerator opening sensor 42 Steering angle sensor 43 Vehicle speed sensor 44 Longitudinal acceleration Sensor 45 Lateral acceleration sensor 50 ECU
50m storage unit 50p CPU
60 history map 61 set time map 100 traveling device

Claims (5)

It suppresses slipping of drive wheels that drive the vehicle,
A slip parameter that is a measure of the slip state of the drive wheel, and a friction parameter that is a measure of the friction between the drive wheel and the road surface, based on the drive torque of the drive wheel, the speed of the drive wheel, and the speed of the vehicle; A history creation unit that creates a history of the relationship and stores the history in a storage means;
And the maximum value and the slip parameter of the friction parameters obtained from the history, based on the said friction parameters at the present time obtained from the history, seen including a driving torque calculation unit for determining the driving torque of the driving wheel ,
The slip parameter obtained from the history is the slip parameter when the friction parameter obtained from the history is maximum,
The drive torque calculator is
While determining the first slip suppression torque based on the maximum value of the friction parameter obtained from the history and the friction parameter at the current time obtained from the history,
The speed of the vehicle at the current time, the speed of the drive wheel at the current time, the slip parameter when the friction parameter obtained from the history is maximized, and a set time for the drive wheel to return from the slip state to the grip state; A second slip suppression torque is determined based on
A slip suppression control device characterized in that a value obtained by subtracting the first slip suppression torque and the second slip suppression torque from the drive torque of the drive wheel at the present time is used as the drive torque of the drive wheel. The slip suppression control device according to claim 1 , wherein the driving torque calculation unit changes the set time according to the magnitude of the slip parameter. The set time is changed according to the magnitude of the slip parameter when the vehicle is inclined or when the friction parameter does not have a peak characteristic with respect to the change of the slip parameter. The slip suppression control device according to claim 2 . Slip suppression control apparatus according to claim 2 or 3, characterized in that to shorten the setting time according to the slip parameter increases. The drive torque calculator is
The friction parameter is corrected based on an acceleration of the drive wheel required for the drive wheel to return from a slip state to a grip state in the set time and an actual acceleration of the drive wheel. Item 5. The slip suppression control device according to any one of Items 1 to 4 .

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