JP2022035235A - Control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately stabilize the behavior of a vehicle body.
SOLUTION: A control device 100 has a determination unit for determining whether or not a wheel 11 of a vehicle 1 has slipped, and a required torque of the wheel 11 in each calculation cycle when it is determined that the wheel 11 has slipped. A control unit that determines a lower torque instruction value of the wheel 11 and performs torque down control for reducing the torque output to the wheel 11 to the torque instruction value is provided, and the control unit is provided with a wheel in the torque down control. It is calculated by the first torque instruction value candidate calculated based on the time change amount of the wheel speed of 11 and the inertial moment of the wheel 11, and the feedback control in which the slip ratio of the wheel 11 is controlled to approach the target slip ratio. Of the second torque indicated value candidates, the one having the smaller absolute value is determined as the torque indicated value.
[Selection diagram] Fig. 1

Description

The present invention relates to a control device.

For the purpose of stabilizing the vehicle body behavior, a technique related to torque down control has been proposed as a slip suppression control for suppressing wheel slip. The torque down control is performed when the wheel slips, for example, as disclosed in Patent Document 1, and is a control for reducing the torque of the wheel with respect to the required torque.

Japanese Unexamined Patent Publication No. 2007-049825

In the conventional torque down control by the drive motor, for example, the torque instruction value may be determined by the feedback control after the torque down is performed by the torque down amount according to the time change amount of the wheel speed. In the feedback control, the slip ratio of the wheel is controlled to approach the target slip ratio. Here, in the transmission of torque in the vehicle, a transmission delay occurs before reaching the tire after the torque is output from the drive motor. Therefore, it takes time for the wheel speed to start to decrease after the torque reduction is started. That is, after the torque reduction is started, it takes time for the wheel slip ratio to start to decrease. As a result, the torque indicated value determined by the feedback control becomes excessively small, and the slip ratio of the wheel may drop sharply. In this case, the slip ratio is fully recovered, the tire grips, and the torque down control ends. After that, the wheel slip occurs again, and the torque down control is restarted. Repeated torque down control in this way causes destabilization of vehicle body behavior.

Therefore, in view of such a problem, it is an object of the present invention to provide a control device capable of appropriately stabilizing the vehicle body behavior.

In order to solve the above problems, the control device of the present invention has a determination unit for determining whether or not the wheels of the vehicle have slipped, and a determination unit for determining whether or not the wheels of the vehicle have slipped. A control unit that determines a torque instruction value of a wheel lower than the required torque and performs torque down control for reducing the torque output to the wheel to the torque instruction value is provided, and the control unit is provided with a control unit for torque down control. The first torque indication value candidate calculated based on the time change amount of the wheel speed and the inertial moment of the wheel, and the second torque calculated by the feedback control in which the slip ratio of the wheel is controlled to approach the target slip ratio. The one with the smaller absolute value among the indicated value candidates is determined as the torque indicated value.

The control unit calculates the value obtained by multiplying the difference between the time change amount of the current wheel speed and the target time change amount by the moment of inertia as the torque down amount, and subtracts the torque down amount from the required torque. The value may be determined as the first torque indicated value candidate.

The target time change amount may be a value corresponding to the time change amount of the wheel speed immediately before it is determined that the wheel slip has occurred.

The feedback control may include integral control based on the deviation between the slip ratio and the target slip ratio.

According to the present invention, it is possible to appropriately stabilize the vehicle body behavior.

It is a schematic diagram which shows the schematic structure of the vehicle which mounts the control device which concerns on embodiment of this invention. It is a block diagram which shows an example of the functional structure of the control device which concerns on embodiment of this invention. It is a figure which shows an example of the transition of various state quantities when the torque down control which concerns on a comparative example is executed. It is a flowchart which shows an example of the flow of the process performed by the control device which concerns on embodiment of this invention. It is a figure which shows an example of the transition of various state quantities when the torque down control which concerns on embodiment of this invention is executed. It is a schematic diagram which shows an example of the relationship between a wheel torque and a time change amount of a wheel speed. It is a schematic diagram which shows the relationship between a slip ratio and a grip force.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, other specific numerical values, etc. shown in the embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and the drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate explanations, and elements not directly related to the present invention are not shown. do.

<Vehicle configuration>
With reference to FIGS. 1 and 2, the configuration of the vehicle 1 on which the control device 100 according to the embodiment of the present invention is mounted will be described.

FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle 1. In FIG. 1, the forward direction of the vehicle 1 is the forward direction, the backward direction opposite to the forward direction is the rear direction, and the left and right sides of the vehicle 1 facing the front direction are the left and right directions, respectively. It is shown.

The vehicle 1 is an electric vehicle that includes a drive motor as a drive source and travels by using the torque output from the drive motor.

The vehicle 1 described below is merely an example of a vehicle equipped with the control device according to the present invention, and as will be described later, the configuration of the vehicle equipped with the control device according to the present invention is the vehicle 1. The configuration is not particularly limited.

As shown in FIG. 1, the vehicle 1 includes front wheels 11a, 11b, rear wheels 11c, 11d, a front differential device 13f, a rear differential device 13r, a front wheel drive motor 15f, and a rear wheel drive motor 15r. , Inverters 17f, 17r, battery 19, front wheel motor rotation speed sensor 21f, rear wheel motor rotation speed sensor 21r, and control device 100.

Hereinafter, when the front wheels 11a, the front wheels 11b, the rear wheels 11c, and the rear wheels 11d are not distinguished, these are also simply referred to as wheels 11. When the front wheel drive motor 15f and the rear wheel drive motor 15r are not distinguished, they are also simply referred to as a drive motor 15. When the inverter 17f and the inverter 17r are not distinguished, they are also simply referred to as an inverter 17. Further, when the front wheel motor rotation speed sensor 21f and the rear wheel motor rotation speed sensor 21r are not distinguished, these are also simply referred to as a motor rotation speed sensor 21.

The front wheel drive motor 15f outputs torque for driving the front wheels 11a and 11b. The front wheel 11a corresponds to the left front wheel, and the front wheel 11b corresponds to the right front wheel.

The front wheel drive motor 15f is driven by using the electric power supplied from the battery 19. The front wheel drive motor 15f is connected to the front differential device 13f. The front differential device 13f is connected to the front wheels 11a and 11b via a drive shaft, respectively. The torque output from the front wheel drive motor 15f is transmitted to the front differential device 13f, and then distributed and transmitted to the front wheels 11a and 11b by the front differential device 13f.

The front wheel drive motor 15f is, for example, a multi-phase AC motor, and is connected to the battery 19 via an inverter 17f. The DC power supplied from the battery 19 is converted into AC power by the inverter 17f and supplied to the front wheel drive motor 15f.

The front wheel drive motor 15f may have a function as a generator that generates electricity by using the kinetic energy of the front wheels 11a and 11b, in addition to the function of outputting the drive torque of the front wheels 11a and 11b. When the front wheel drive motor 15f functions as a generator, power is generated by the front wheel drive motor 15f, and braking force due to regenerative braking is applied to the vehicle 1. The AC power generated by the front wheel drive motor 15f is converted into DC power by the inverter 17f and supplied to the battery 19. As a result, the battery 19 is charged.

The rear wheel drive motor 15r outputs torque for driving the rear wheels 11c and 11d. The rear wheel 11c corresponds to the left rear wheel, and the rear wheel 11d corresponds to the right rear wheel.

The rear wheel drive motor 15r is driven by using the electric power supplied from the battery 19. The rear wheel drive motor 15r is connected to the rear differential device 13r. The rear differential device 13r is connected to the rear wheels 11c and 11d via a drive shaft, respectively. The torque output from the rear wheel drive motor 15r is transmitted to the rear differential device 13r, and then distributed and transmitted to the rear wheels 11c and 11d by the rear differential device 13r.

The rear wheel drive motor 15r is, for example, a multi-phase AC motor, and is connected to the battery 19 via an inverter 17r. The DC power supplied from the battery 19 is converted into AC power by the inverter 17r and supplied to the rear wheel drive motor 15r.

The rear wheel drive motor 15r may have a function as a generator that generates electricity by using the kinetic energy of the rear wheels 11c and 11d, in addition to the function of outputting the drive torque of the rear wheels 11c and 11d. When the rear wheel drive motor 15r functions as a generator, power is generated by the rear wheel drive motor 15r, and braking force due to regenerative braking is applied to the vehicle 1. The AC power generated by the rear wheel drive motor 15r is converted into DC power by the inverter 17r and supplied to the battery 19. As a result, the battery 19 is charged.

The front wheel motor rotation speed sensor 21f detects the rotation speed of the front wheel drive motor 15f and outputs the detection result. The rotation speed of the front wheel drive motor 15f detected by the front wheel motor rotation speed sensor 21f may correspond to information indicating the wheel speeds of the front wheels 11a and 11b.

The rear wheel motor rotation speed sensor 21r detects the rotation speed of the rear wheel drive motor 15r and outputs the detection result. The rotation speed of the rear wheel drive motor 15r detected by the rear wheel motor rotation speed sensor 21r may correspond to information indicating the wheel speeds of the rear wheels 11c and 11d.

The control device 100 includes a CPU (Central Processing Unit) which is an arithmetic processing unit, a ROM (Read Only Memory) which is a storage element for storing programs and arithmetic parameters used by the CPU, and parameters which are appropriately changed in the execution of the CPU. A RAM (Random Access Memory) or the like, which is a storage element for temporarily storing the above, is included.

The control device 100 communicates with each device mounted on the vehicle 1. For example, the control device 100 communicates with the inverter 17f, the inverter 17r, the front wheel motor rotation speed sensor 21f, the rear wheel motor rotation speed sensor 21r, and the like. Communication between the control device 100 and each device is realized by using, for example, CAN (Control Area Area Network) communication.

The function of the control device 100 according to the present embodiment may be divided by a plurality of control devices, or the plurality of functions may be realized by one control device. When the function of the control device 100 is divided by a plurality of control devices, the plurality of control devices may be connected to each other via a communication bus such as CAN.

FIG. 2 is a block diagram showing an example of the functional configuration of the control device 100.

For example, as shown in FIG. 2, the control device 100 includes an acquisition unit 110, a determination unit 120, and a control unit 130.

The acquisition unit 110 acquires various information used in the processing performed by the determination unit 120 and the control unit 130, and outputs the information to the determination unit 120 and the control unit 130. For example, the acquisition unit 110 acquires information from the front wheel motor rotation speed sensor 21f and the rear wheel motor rotation speed sensor 21r.

The determination unit 120 makes various determinations. The determination result by the determination unit 120 is used for the processing performed by the control unit 130. In particular, the determination unit 120 makes a slip determination to determine whether or not the wheel 11 has slipped. Slip means a phenomenon in which the slip ratio of the wheel 11 becomes excessively large and the wheel 11 slips. The slip ratio is a value obtained by dividing the difference between the wheel speed and the vehicle speed by the vehicle speed. Slip can occur, for example, when the vehicle 1 enters a low μ road such as a frozen running road.

The control unit 130 controls the traveling of the vehicle 1 by controlling the operation of each device in the vehicle 1. In particular, the control unit 130 controls the operations of the front wheel drive motor 15f and the rear wheel drive motor 15r.

Specifically, the control unit 130 controls the supply of electric power between the battery 19 and the front wheel drive motor 15f by controlling the operation of the switching element of the inverter 17f. As a result, the torques of the front wheels 11a and 11b output by the front wheel drive motor 15f are controlled. Further, the control unit 130 controls the supply of electric power between the battery 19 and the rear wheel drive motor 15r by controlling the operation of the switching element of the inverter 17r. As a result, the torques of the rear wheels 11c and 11d output by the rear wheel drive motor 15r are controlled. As described above, the control unit 130 can individually control the torque of the front wheels 11a and 11b and the torque of the rear wheels 11c and 11d.

The control unit 130 can switch the drive mode of the vehicle 1 between the front wheel drive mode and the four-wheel drive mode. The front wheel drive mode is a drive mode in which the front wheels 11a and 11b are driven without driving the rear wheels 11c and 11d. The four-wheel drive mode is a drive mode in which the front wheels 11a and 11b and the rear wheels 11c and 11d are driven. The control unit 130 may switch the drive mode according to, for example, an input operation by the driver. Further, the control unit 130 may switch the drive mode according to, for example, the traveling state of the vehicle 1. The control unit 130 can execute the rear wheel drive mode in which the rear wheels 11c and 11d are driven without driving the front wheels 11a and 11b, instead of the front wheel drive mode or in addition to the front wheel drive mode. You may.

Here, when it is determined that the wheel 11 has slipped, the control unit 130 performs torque down control as a slip suppressing control for suppressing the slip of the wheel 11. In the torque down control, the control unit 130 performs torque reduction that reduces the torque of the wheel 11 with respect to the required torque. Specifically, the control unit 130 determines a torque instruction value of the wheel 11 that is lower than the required torque of the wheel 11 in each calculation cycle, and torques the torque output from the drive motor 15 to the wheel 11 to the torque instruction value. Bring it down.

The control unit 130 individually executes torque down control for the front wheels 11a and 11b and torque down control for the rear wheels 11c and 11d. That is, when it is determined that the front wheels 11a and 11b have slipped, the control unit 130 performs torque down control for the front wheels 11a and 11b. Further, when it is determined that the rear wheels 11c and 11d have slipped, the control unit 130 performs torque down control for the rear wheels 11c and 11d.

In the present embodiment, it is possible to appropriately stabilize the vehicle body behavior by devising the torque instruction value determination process in each calculation cycle of the torque down control. The details of the processing related to the torque down control by the control device 100 will be described later.

<Operation of control device>
Subsequently, the operation of the control device 100 according to the embodiment of the present invention will be described with reference to FIGS. 3 to 7.

FIG. 3 is a diagram showing an example of changes in various state quantities when the torque down control according to the comparative example is executed. In FIG. 3, as various state quantities, the wheel speed L1 of the wheel 11 to be torque down controlled, the target wheel speed L2 which is the wheel speed at which the slip ratio is the target slip ratio, the vehicle speed L3, and the torque down control are targeted. With the output torque L4 which is the torque output from the drive motor 15 with respect to the wheel 11, the target torque L5 which is the torque of the wheel 11 whose slip ratio is the target slip ratio, and the torque of the wheel 11 which is balanced with the road surface reaction force. A certain road surface reaction force equivalent torque L6 is shown. When the torque of the wheel 11 becomes the road surface reaction force equivalent torque L6, the slip ratio becomes 0%.

In the example shown in FIG. 3, the torque down control is started at time t1. In the comparative example, the torque indicated value is determined to be the target torque L5 at the time t1 which is the first calculation cycle in the torque down control. Therefore, the output torque L4 becomes the target torque L5 near the time t2, which is the second calculation cycle. Specifically, the target torque L5 can be determined based on the time change amount of the wheel speed L1 and the moment of inertia of the wheel 11. Then, at the time t2, t3, t4, t5, and t6, which are the second and subsequent calculation cycles, the torque indicated value is determined by the feedback control in which the slip ratio is controlled to approach the target slip ratio.

Here, in the transmission of torque in the vehicle 1, after the torque is output from the drive motor 15, a transmission delay occurs before reaching the tire. Therefore, the change in the wheel speed L1 is delayed with respect to the change in the output torque L4. Therefore, in the example shown in FIG. 3, although the output torque L4 starts to decrease from the time t1, the wheel speed L1 continues to increase to the vicinity of the time t4. That is, the recovery of the slip ratio does not start until around time t4. As a result, the torque indicated value determined by the feedback control in the second and subsequent calculation cycles becomes excessively small. In particular, when the feedback control includes the integral control, the torque instruction value tends to be maintained in an excessively small state due to the action of the component of the integral control.

For example, in the example shown in FIG. 3, the output torque L4 is reduced to a negative value in many times between the time t2 and the time t6. As a result, from time t4 to time t5, the wheel speed L1 drops sharply, the slip ratio is fully recovered, and the tire grips. As a result, the torque down control ends near the time t5. After that, at around time t6, the wheel 11 slips again, and the torque down control is restarted. Repeated torque down control in this way causes destabilization of vehicle body behavior.

Therefore, in the present embodiment, the torque instruction value determination process in each calculation cycle of the torque down control is devised so that the torque down control is suppressed from being repeatedly performed as in the above comparative example. Hereinafter, the processing related to the torque down control performed by the control device 100 according to the present embodiment will be described.

FIG. 4 is a flowchart showing an example of the flow of processing performed by the control device 100 according to the present embodiment. The control flow shown in FIG. 4 is started when the torque down control is not executed. After the control flow shown in FIG. 4 is completed, the control flow is started, for example, at a set time interval.

FIG. 5 is a diagram showing an example of changes in various state quantities when the torque down control according to the present embodiment is executed. In FIG. 5, as in FIG. 3, the wheel speed L1, the target wheel speed L2, the vehicle speed L3, the output torque L4, the target torque L5, and the road surface reaction force of the wheel 11 to be torque down controlled are shown as various state quantities. The equivalent torque L6 is shown.

Hereinafter, the control flow shown in FIG. 4 will be described with reference to FIG. 5 as appropriate.

When the control flow shown in FIG. 4 is started, first, in step S101, the determination unit 120 determines whether or not the wheel 11 has slipped. When it is determined that the wheel 11 has slipped (step S101 / YES), the control device 100 starts the torque down control and proceeds to step S102. When it is determined that the wheel 11 has not slipped (step S101 / NO), the control device 100 ends the control flow shown in FIG.

Here, when the wheel 11 slips, the wheel speed of the wheel 11 suddenly increases, so that a large time change in the rotation speed of the drive motor 15 connected to the wheel 11 occurs. Therefore, the determination unit 120 determines that the wheel 11 has slipped, for example, when the state in which the time change amount of the rotation speed of the drive motor 15 is equal to or more than the time change amount threshold value continues for the duration time threshold value or more.

Specifically, the determination unit 120 individually executes the slip determination for the front wheels 11a and 11b and the slip determination for the rear wheels 11c and 11d. That is, the determination unit 120 determines that the front wheels 11a and 11b have slipped when the state in which the time change amount of the rotation speed of the front wheel drive motor 15f is equal to or more than the time change amount threshold value continues for the duration time threshold value or more. Further, the determination unit 120 determines that the rear wheels 11c and 11d have slipped when the state in which the time change amount of the rotation speed of the rear wheel drive motor 15r is equal to or more than the time change amount threshold value continues for the duration time threshold value or more. do.

For example, in the example shown in FIG. 5, it is determined that the wheel 11 has slipped at time t1, and the torque down control is started.

If YES is determined in step S101 in FIG. 4, in step S102, the control unit 130 determines the torque instruction value based on the time change amount of the wheel speed and the moment of inertia of the wheel 11. Then, in step S103 after step S102, the control unit 130 reduces the torque of the wheel 11 to the torque indicated value. The amount of change in wheel speed with time means the amount of change in wheel speed per unit time.

The torque indicated value determined in step S102 corresponds to a theoretical value determined by a theoretical formula focusing on the relationship between the torque of the wheel 11 and the time change amount of the wheel speed. FIG. 6 is a schematic diagram showing an example of the relationship between the torque of the wheel 11 and the amount of time change of the wheel speed.

The torque T1 in FIG. 6 corresponds to the road surface reaction force equivalent torque L6 in FIG. That is, the torque T1 is a torque that balances with the road surface reaction force. When the torque of the wheel 11 is smaller than the torque T1, the wheel 11 does not slip, and when the torque of the wheel 11 exceeds the torque T1, the wheel 11 slips. Therefore, in the example shown in FIG. 6, in the process in which the torque of the wheel 11 increases to the torque T1, the amount of time change of the wheel speed increases with a small inclination. Then, after the torque of the wheel 11 exceeds the torque T1, the time change amount of the wheel speed increases with a large inclination as compared with the case where the torque of the wheel 11 is smaller than the torque T1.

For example, the control unit 130 calculates the torque down amount ΔT using the following equation (1) focusing on the relationship between the torque of the wheel 11 and the time change amount of the wheel speed, and subtracts the torque down amount ΔT from the required torque. The value obtained in this way is determined as the torque indicated value.

ΔT = I (ω'1-ω'2 x K) ... (1)

In formula (1), I represents the moment of inertia of the wheel 11. ω'1 indicates the amount of time change of the wheel speed of the current wheel 11. ω'2 indicates the amount of time change in the wheel speed of the wheel 11 immediately before it is determined that the wheel 11 has slipped. K indicates a coefficient. As will be described later, (ω'2 × K) corresponds to the target time change amount which is the target value of the time change amount of the wheel speed.

As shown in FIG. 6, since the wheel 11 is slipping during the torque down control, it is determined that the current wheel speed change amount ω'1 of the wheel 11 has caused the wheel 11 to slip. It is larger than the time change amount ω'2 of the wheel speed of the wheel 11 immediately before the slip. In the example of FIG. 6, the current required torque of the wheel 11 is torque T2. The time change amount ω'2 corresponds to the time change amount of the wheel speed when the torque is the torque T1. Further, when the torque of the wheel 11 is larger than the torque T1, the slope of the amount of change in the wheel speed with respect to the torque is 1 / I.

For example, in the example of FIG. 6, when K in the equation (1) is 1, the torque down amount ΔT is (T2-T1). That is, the torque indicated value is the torque T1 corresponding to the road surface reaction force equivalent torque L6 in FIG. Therefore, the target time change amount of the wheel speed is ω'2.

Further, for example, in the example of FIG. 6, the torque down amount ΔT can be made smaller than (T2-T1) by setting K in the equation (1) to a value larger than 1. As a result, the torque indicated value can be set to the target torque L5 in FIG. In this case, the target time change amount of the wheel speed is a value (ω'2 × K) obtained by multiplying ω'2 by K, which is a value larger than 1.

As described above, the control unit 130 multiplies, for example, the difference between the time change amount ω'1 of the wheel speed of the current wheel 11 and the target time change amount (ω'2 × K) by the moment of inertia I of the wheel 11. The value obtained by subtracting the torque down amount ΔT from the required torque is calculated as the torque down amount ΔT, and the value obtained by subtracting the torque down amount ΔT is determined as the torque indicated value. The target time change amount (ω'2 × K) is a value corresponding to the time change amount ω'2 of the wheel speed of the wheel 11 immediately before it is determined that the wheel 11 has slipped.

For example, in the example shown in FIG. 5, at the time t1 which is the first calculation cycle in the torque down control, the control unit 130 uses the above equation (1) to set the torque indicated value to the target torque L5. To decide. Therefore, the output torque L4 becomes the target torque L5 near the time t2, which is the second calculation cycle.

Following step S103 in FIG. 4, in step S104, the determination unit 120 determines whether or not the end condition of the torque down control is satisfied. When it is determined that the end condition of the torque down control is satisfied (step S104 / YES), the control device 100 proceeds to step S105, ends the torque down control, and ends the control flow shown in FIG. If it is determined that the end condition of the torque down control is not satisfied (step S104 / NO), the control device 100 proceeds to step S106.

The end condition of the torque down control is, for example, that the slip ratio of the wheel 11 which is the target of the torque down control has recovered to the vicinity of 0%. This termination condition can be satisfied when the vehicle 1 enters a high μ road. The control device 100 may terminate the torque down control when other termination conditions other than the above conditions are satisfied. For example, another termination condition may be that the operation of depressing the accelerator pedal is released and the driver no longer requests the accelerator. Further, for example, another termination condition may be that the brake pedal is depressed and a brake request is generated by the driver.

If NO is determined in step S104, in step S106, the determination unit 120 determines whether or not the cycle time has elapsed. If it is determined that the cycle time has elapsed (step S106 / YES), the control device 100 proceeds to step S107. If it is determined that the cycle time has not elapsed (step S106 / NO), the control device 100 returns to step S104. The cycle time can be appropriately set according to the specifications of each device in the vehicle 1.

If YES is determined in step S106, in step S107, the control unit 130 calculates the first torque indicated value candidate based on the time change amount of the wheel speed and the moment of inertia I of the wheel 11.

The first torque indicated value candidate calculated in step S107 is determined by a theoretical formula focusing on the relationship between the torque of the wheel 11 and the time change amount of the wheel speed, similarly to the torque indicated value determined in step S102. Corresponds to the theoretical value. The control unit 130 calculates the torque down amount ΔT using the above equation (1), for example, in the same manner as in the torque instruction value calculation process in step S102. That is, the control unit 130 obtains, for example, by multiplying the difference between the time change amount ω'1 of the wheel speed of the current wheel 11 and the target time change amount (ω'2 × K) by the moment of inertia I of the wheel 11. The value to be obtained is calculated as the torque down amount ΔT, and the value obtained by subtracting the torque down amount ΔT from the required torque is determined as the first torque indicated value candidate.

Next, in step S108, the control unit 130 calculates a second torque instruction value candidate using feedback control.

In the above feedback control, the slip ratio of the wheel 11 is controlled to approach the target slip ratio. The target slip ratio is set to a value within a range in which the grip force, which is the frictional force generated between the tire and the road surface, is effectively recovered.

FIG. 7 is a schematic diagram showing the relationship between the slip ratio and the grip force. As shown in FIG. 7, in general, the vertical grip force, which is a traveling direction component of the grip force, increases in the process of increasing the slip ratio of the wheel 11 from 0% to about 20%, and then the slip ratio of the wheel 11 is increased. Decreases in the process of increasing. Further, in general, the lateral grip force, which is a component perpendicular to the traveling direction of the grip force, decreases as the slip ratio of the wheel 11 increases. Therefore, in order to achieve both the vertical grip force and the horizontal grip force at a high level, it is preferable to adjust the slip ratio of the wheel 11 within the target region of about 10% to about 20%. Therefore, the target slip ratio is set to a value within the above-mentioned target region, which is a range in which the grip force of the tire of the wheel 11 is effectively recovered, for example.

The control unit 130 calculates a second torque indicated value candidate by using PID control based on the deviation between the slip ratio of the wheel 11 and the target slip ratio, for example. In this case, the calculated second torque indicated value candidate is represented by, for example, the following equation (2).

Tc = Tp + Ti + Td ・ ・ ・ (2)

In the formula (2), Tc indicates a second torque indicated value candidate. Tp indicates the torque of the P component, which is a component of proportional control based on the above deviation. The torque Tp of the P component is obtained by multiplying the above deviation by the gain. Ti indicates the torque of the I component, which is a component of the integral control based on the above deviation. The torque Ti of the I component is obtained by multiplying the integrated value of the above deviations by the gain. Td indicates the torque of the D component, which is a component of the differential control based on the integrated value of the deviation. The torque Td of the D component is obtained by multiplying the differential value of the above deviation by the gain.

The feedback control used in the calculation of the second torque indicated value candidate is not limited to the PID control. For example, PID control may be replaced by PI control. That is, the torque Td may be omitted from the equation (2).

Following step S108 in FIG. 4, in step S109, the determination unit 120 determines whether or not the absolute value of the first torque instruction value candidate is smaller than the absolute value of the second torque instruction value candidate. When it is determined that the absolute value of the first torque indicated value candidate is smaller than the absolute value of the second torque indicated value candidate (step S109 / YES), the control unit 130 proceeds to step S110 and selects the first torque indicated value candidate. Determined as the torque indicated value. When it is determined that the absolute value of the first torque indicated value candidate is larger than the absolute value of the second torque indicated value candidate (step S109 / NO), the control unit 130 proceeds to step S111 and selects the second torque indicated value candidate. Determined as the torque indicated value. When the absolute value of the first torque instruction value candidate matches the absolute value of the second torque instruction value candidate, the control unit 130 may determine the first torque instruction value candidate as the torque instruction value, and the second torque instruction value candidate may be determined. The torque indicated value candidate may be determined as the torque indicated value.

Following step S110 or step S111, in step S112, the control unit 130 reduces the torque of the wheel 11 to the torque indicated value.

Next, in step S113, the determination unit 120 determines whether or not the end condition of the torque down control is satisfied. When it is determined that the end condition of the torque down control is satisfied (step S113 / YES), the control device 100 proceeds to step S114, ends the torque down control, and ends the control flow shown in FIG. When it is determined that the end condition of the torque down control is not satisfied (step S113 / NO), the control device 100 proceeds to step S115. The end condition of the torque down control is the same as the end condition in step S104.

If NO is determined in step S113, in step S115, the determination unit 120 determines whether or not the cycle time has elapsed. When it is determined that the cycle time has elapsed (step S115 / YES), the control device 100 returns to step S107. If it is determined that the cycle time has not elapsed (step S115 / NO), the control device 100 returns to step S113.

As described above, in the present embodiment, the control unit 130 gives the first torque instruction calculated based on the time change amount of the wheel speed and the moment of inertia I of the wheel 11 in the second and subsequent calculation cycles in the torque down control. The smaller absolute value of the value candidate and the second torque indicated value candidate calculated by the feedback control in which the slip ratio of the wheel 11 is controlled to approach the target slip ratio is determined as the torque indicated value.

For example, in the example shown in FIG. 5, the output torque L4 starts to decrease from the time t1 as in the comparative example shown in FIG. 3, but the wheel speed L1 continues to increase to the vicinity of the time t4. That is, the recovery of the slip ratio does not start until around time t4. As a result, the second torque indicated value candidate calculated by the feedback control in the second and subsequent calculation cycles (for example, time t2, t3, t4, etc.) becomes excessively small.

On the other hand, the first torque indicated value candidate calculated based on the time change amount of the wheel speed and the moment of inertia I of the wheel 11 in the second and subsequent calculation cycles (for example, time t2, t3, t4, etc.) is the first calculation. The target torque L5 is obtained in the same manner as the torque indicated value determined at the time t1 which is the cycle. Therefore, in the second and subsequent calculation cycles (for example, time t2, t3, t4, etc.), the first torque indicated value candidate is determined as the torque indicated value. As a result, it is suppressed that the output torque L4 becomes small to the extent that it becomes a negative value.

As a result, after the time t4, it is suppressed that the wheel speed L1 suddenly decreases, so that the slip ratio is completely recovered and the tire is suppressed from gripping. Therefore, in the example shown in FIG. 5, the torque down control is not terminated near the time t5, and the wheel speed L1 is controlled to approach the target wheel speed L2. That is, the torque down control controls the slip ratio so as to approach the target slip ratio. As described above, according to the present embodiment, the torque down control is suppressed from being repeatedly performed, so that the vehicle body behavior can be appropriately stabilized.

<Effect of control device>
Subsequently, the effect of the control device 100 according to the embodiment of the present invention will be described.

In the control device 100 according to the present embodiment, the control unit 130 has a first torque instruction value candidate calculated based on the time change amount of the wheel speed and the moment of inertia I of the wheel 11 in the torque down control, and the wheel 11. The smaller absolute value of the second torque indicated value candidates calculated by the feedback control controlled so that the slip ratio approaches the target slip ratio is determined as the torque indicated value. As a result, it is possible to prevent the torque instruction value from becoming excessively small during the execution of the torque down control. Therefore, it is suppressed that the wheel speed of the wheel 11 which is the target of the torque down control suddenly decreases, so that the slip ratio is completely recovered and the tire is suppressed from gripping. Therefore, it is possible to appropriately stabilize the behavior of the vehicle body because the torque down control is suppressed from being repeatedly performed.

Further, in the control device 100 according to the present embodiment, the control unit 130 has the difference between the time change amount ω'1 of the wheel speed of the current wheel 11 and the target time change amount (ω'2 × K) of the wheel 11. It is preferable to calculate the value obtained by multiplying the moment of inertia I as the torque down amount ΔT, and determine the value obtained by subtracting the torque down amount ΔT from the required torque as the first torque indicated value candidate. Thereby, a value that can bring the wheel speed closer to the target time change amount (ω'2 × K) can be determined as the first torque indicated value candidate.

Further, in the control device 100 according to the present embodiment, the target time change amount (ω'2 × K) is the time change amount ω'2 of the wheel speed of the wheel 11 immediately before it is determined that the wheel 11 has slipped. It is preferable that the value corresponds to. Thereby, the target torque L5 or the road surface reaction force equivalent torque L6 can be determined as the first torque indicated value candidate.

Further, in the control device 100 according to the present embodiment, it is preferable that the feedback control used in the calculation of the second torque indicated value candidate includes integral control based on the deviation between the slip ratio of the wheel 11 and the target slip ratio. Here, if the torque indicated value calculated by the feedback control becomes excessively small during the execution of the torque down control, the torque indicated value is maintained in an excessively small state due to the action of the I component, which is a component of the integral control. It will be easier. Therefore, when the control including the integral control is used as the feedback control, the effect of appropriately stabilizing the vehicle body behavior is particularly effective.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, and various modifications in the scope of claims are described. It goes without saying that the modified examples also belong to the technical scope of the present invention.

For example, although the configuration of the vehicle 1 has been described above with reference to FIG. 1, the configuration of the vehicle according to the present invention is not limited to such an example. The vehicle according to the present invention may be, for example, a vehicle 1 shown in FIG. 1 with some components deleted, added or modified. Further, the vehicle according to the present invention may be, for example, a vehicle in which a drive motor 15 is provided for each wheel 11. A part of the drive source in the vehicle according to the present invention may be a drive source other than the drive motor (for example, an engine or the like).

Further, for example, the processes described by using the flowchart in the present specification do not necessarily have to be executed in the order shown in the flowchart. Further, additional processing steps may be adopted, and some processing steps may be omitted.

The present invention can be used for a control device.

1 Vehicle 11 Wheels 13f Front differential device 13r Rear differential device 15 Drive motor 17 Inverter 19 Battery 21 Motor rotation speed sensor 100 Control device 110 Acquisition unit 120 Judgment unit 130 Control unit

Claims (4)

A determination unit that determines whether or not the wheels of the vehicle have slipped,
When it is determined that the wheel slip has occurred, the torque indicated value of the wheel lower than the required torque of the wheel is determined in each calculation cycle, and the torque output to the wheel is torqued to the torque indicated value. A control unit that controls the torque down to bring it down,
Equipped with
In the torque down control, the control unit sets the first torque indicated value candidate calculated based on the time change amount of the wheel speed of the wheel and the moment of inertia of the wheel and the slip rate of the wheel as the target slip rate. Of the second torque instruction value candidates calculated by the feedback control controlled to approach each other, the one having the smaller absolute value is determined as the torque instruction value.
Control device. The control unit
The value obtained by multiplying the difference between the current time change amount of the wheel speed and the target time change amount by the moment of inertia is calculated as the torque down amount.
A value obtained by subtracting the torque down amount from the required torque is determined as the first torque indicated value candidate.
The control device according to claim 1. The target time change amount is a value corresponding to the time change amount of the wheel speed immediately before it is determined that the wheel slip has occurred.
The control device according to claim 2. The feedback control includes integral control based on the deviation between the slip ratio and the target slip ratio.
The control device according to any one of claims 1 to 3.

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