JP2009077460A - Drive control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize the behavior of a vehicle at an early stage by suppressing a slip generated in a drive wheel, at an earlier stage. <P>SOLUTION: There is obtained upper-limit limiting drive-wheel acceleration a2 which the drive wheel can generate from required drive wheel acceleration a1 required for the drive wheel arranged at the vehicle, and the frictional coefficient between the drive wheel of the vehicle and a road surface which the drive wheel contacts with (step S102). Generative drive-wheel acceleration a3, which the drive wheel of the vehicle can generate is obtained, on the basis of the required drive-wheel acceleration a1 and the limit drive-wheel acceleration a2 (step S104). Then, a torque correction value Tc of the drive wheel is obtained, on the basis of the obtained generative drive-wheel acceleration a3 and actual drive-wheel acceleration ar which the drive wheel presently is generating (step S106), and a torque command value Ts to the drive wheel is corrected (step S107). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drive control device for suppressing slip generated in drive wheels of a vehicle.

  When driving wheels of a vehicle such as a passenger car or a truck slip, the driving efficiency is reduced because the power generated by the power generation source cannot be effectively converted into braking / driving force. 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 technique for limiting the output of an electric motor on the assumption that a wheel slip occurs when the rotational angular acceleration of the electric motor exceeds a predetermined threshold.

JP 2005-51849 A paragraph number 0008, FIG.

  However, the technique disclosed in Patent Document 1 limits the output of the electric motor after a slip occurs on the wheel. As a result, slip occurs until the output of the motor is suppressed. For this reason, it is necessary to suppress the slip generated in the drive wheels at an earlier stage and stabilize the behavior of the vehicle earlier. Therefore, the present invention has been made in view of the above, and provides a drive control device capable of suppressing the slip generated in the drive wheels at an earlier stage and stabilizing the behavior of the vehicle at an early stage. With the goal.

  In order to solve the above-described problems and achieve the object, a drive control device according to the present invention includes a required drive wheel acceleration required for a drive wheel provided in a vehicle, and a road surface on which the drive wheel of the vehicle and the drive wheel are in contact with each other. The driving wheel is generated on the basis of the required driving wheel acceleration and the limit driving wheel acceleration, and an acceleration calculation unit that obtains an upper limit driving wheel acceleration that the driving wheel can generate from a friction coefficient between A drive torque to be applied to the drive wheel is obtained based on a possible acceleration calculation unit that obtains a possible drive wheel acceleration, the drive wheel acceleration that can be generated, and an acceleration that the drive wheel is currently generating. And a braking / driving force calculation unit.

  As described above, the driving torque of the driving wheel provided in the vehicle is obtained in consideration of the required driving wheel acceleration and the limit driving wheel acceleration, so that the delay due to the sampling period of the wheel speed, the communication delay of the ECU, or the driving system of the vehicle Even if it takes time for the driving force of the driving wheel to actually decrease due to a delay due to twisting of the driving wheel, excessive slip of the driving wheel can be suppressed. As a result, the slip generated on the drive wheels can be suppressed at an earlier stage, and the behavior of the vehicle can be stabilized at an early stage.

  As a preferred aspect of the present invention, the braking / driving force calculation unit is applied to the driving wheel at the present time when the possible driving wheel acceleration is larger than the acceleration that the driving wheel is currently generating. It is preferable to maintain the driving torque.

  According to this invention, the slip which generate | occur | produces in a driving wheel can be suppressed at an early stage, and the behavior of a vehicle can be stabilized early.

  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. A power generation source that can control the braking / driving force is sufficient. 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. Further, the slip of the drive wheel is a slip having an unacceptable magnitude in driving, and is a slip when the friction coefficient between the drive wheel and the road surface exceeds the maximum value.

  In this embodiment, the upper limit drive wheel that can be generated from the required drive wheel acceleration required for the drive wheel provided in the vehicle and the coefficient of friction between the drive wheel of the vehicle and the road surface in contact with the drive wheel. An acceleration is obtained, and a possible drive wheel acceleration capable of generating a drive wheel of the vehicle is obtained based on the obtained required drive wheel acceleration and the limit drive wheel acceleration. A feature is that the driving torque of the driving wheel is obtained based on the obtained drive wheel acceleration that can be generated and the acceleration that the driving wheel is currently generating.

  FIG. 1 is a schematic diagram illustrating a configuration of a vehicle including a traveling device according to the present 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 present 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 the present 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 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, the vehicle 1 is a so-called four-wheel drive type vehicle in which all the wheels, that is, the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl, and the right rear wheel 2rr serve as drive wheels. Among these drive wheels, 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. The vehicle 1 is not limited to a vehicle having all wheels as drive wheels, and may drive only the front wheels (left front wheel 2fl and right front wheel 2fr) or rear wheels (left rear wheel 2rl and right rear wheel 2rr). Only) may be driven.

  In the traveling apparatus 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 braking / driving force of the wheel 2rr is adjusted. In the present embodiment, the total braking / driving force F_all of the traveling device 100 and the left front wheel 2fl, the right front wheel 2fr, the left rear wheel 2rl, and the right rear wheel 2rr are determined by the opening of the accelerator 5 detected by the accelerator opening sensor 41. The braking / driving force of the wheel is controlled.

  In the slip suppression control according to the present embodiment, the braking / 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 drive control device 30 incorporated in the ECU 50. That is, in the slip suppression control according to the present embodiment, the drive control device 30 exhibits a function as braking / driving force changing means for changing the braking / driving force of each driving wheel provided in the vehicle 1. In the present embodiment, the braking / driving forces 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 the present 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 a left front resolver 40fl, a right front resolver 40fr, a left rear resolver 40rl, and a 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. The inverter 6 includes a left front motor inverter 6fl that drives the left front motor 10fl, a right front motor inverter 6fr that drives the right front motor 10fr, a left rear motor inverter 6rl that drives the left rear motor 10rl, and a right It is composed of a right rear motor inverter 6rr that drives the rear motor 10rr. Thus, in this embodiment, it is comprised by four inverters corresponding to each electric motor, and one electric motor is controlled by one inverter.

  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.

  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 the present 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.

  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. Further, the left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr are referred to as the motor 10 as necessary, and the left front resolver 40fl, the right front resolver 40fr, the left rear resolver 40rl, The right rear resolver 40rr is referred to as a resolver 40 as necessary.

  FIG. 2 is a conceptual diagram illustrating wheel speed, road surface reaction force, and the like. FIG. 3A is an explanatory diagram illustrating a relationship between a friction coefficient between a wheel and a road surface and a slip ratio. FIG. 3-2 is an explanatory diagram illustrating a change over time in vehicle speed or wheel speed. As shown in FIG. 3A, the friction coefficient μ between the drive wheel 2 and the road surface GL included in the vehicle 1 shown in FIG. 2 increases with an increase in the slip ratio slip (= (Vw−Vc) / Vw). . The friction coefficient μ reaches a maximum value (maximum friction coefficient) μmax at a certain slip ratio, and thereafter decreases as the slip ratio slip increases. The slip ratio at the maximum friction coefficient μmax is slip_max. When the driving wheel 2 shown in FIG. 2 slips, the rotational speed (wheel speed) Vw of the driving wheel 2 and the speed (vehicle speed) Vc of the vehicle 1 change as shown in FIG. 3-2. The time t shown in FIG. 3-2 corresponds to the time t shown in FIG. 3-1, and the maximum friction coefficient μmax is between t = 3 and t = 4.

  Conventionally, after the slip ratio of the drive wheel 2 exceeds the control threshold slip1 set based on the maximum friction coefficient μmax, that is, the friction coefficient μ between the drive wheel 2 and the road surface GL exceeds the maximum friction coefficient μmax. After that, control for suppressing the slip of the drive wheel 2 (for example, reducing the drive force of the drive wheel 2) has been executed. However, if the driving force of the driving wheel 2 is reduced after exceeding the maximum friction coefficient μmax, the delay due to the sampling period of the rotational speed Vw of the driving wheel 2, the communication delay of the ECU 50, or the driving system of the vehicle 1 A large slip occurs in the drive wheel 2 until the drive force of the drive wheel 2 actually decreases due to a delay due to twisting or the like.

  Further, since the peak value of the maximum friction coefficient μmax or the road surface reaction force Ftrc is obtained by comparison with the previous value, it cannot be obtained unless the maximum friction coefficient μmax or the peak value of the road surface reaction force Ftrc is exceeded. When the maximum friction coefficient μmax or the peak value of the road surface reaction force Ftrc is exceeded, the rotational speed Vw of the drive wheel 2 increases rapidly. Conventionally, the maximum friction coefficient μmax or the peak value of the road surface reaction force Ftrc is accurately determined. Could not be estimated. For this reason, it is determined that the driving wheel 2 has slipped even though the driving wheel 2 has not slipped, and the driving force of the driving wheel 2 is reduced or the driving wheel 2 is slipping. Regardless of this, it is determined that the driving wheel 2 is not slipping, and the driving force of the driving wheel 2 may not be reduced. As a result, there is a possibility that the control is not appropriate for the behavior of the vehicle 1.

  In the present embodiment, the upper limit acceleration that the driving wheel 2 can generate is determined from the acceleration required for the driving wheel 2 included in the vehicle 1 and the friction coefficient μ between the driving wheel 2 included in the vehicle 1 and the road surface GL. The acceleration that can be generated by the driving wheel 2 is obtained. Then, the braking / driving force of the driving wheel 2 is obtained from the acceleration that can be generated by the driving wheel 2 and the acceleration that the driving wheel 2 is currently generating, and the driving wheel 2 is driven.

  As a result, the braking / driving force of the drive wheel 2 is controlled immediately before the slip occurs on the drive wheel 2, that is, before the friction coefficient μ between the drive wheel 2 and the road surface GL exceeds the maximum friction coefficient μmax. As a result, the behavior of the vehicle 1 can be stabilized. In addition, since the degree of increase in slip of the drive wheel 2 (slip acceleration) after exceeding the maximum friction coefficient μmax can be reduced, the estimation accuracy of the friction coefficient μ between the drive wheel 2 and the road surface GL is improved. To do.

  FIG. 4 is a control block diagram of drive control according to the present embodiment. FIG. 5 is a conceptual diagram showing the relationship between the road surface reaction force and the slip ratio. FIG. 6A is an explanatory diagram of a relationship between a friction coefficient between a wheel and a road surface and a slip ratio. FIG. 6B is an explanatory diagram illustrating a change over time in the vehicle speed or the wheel speed when the drive control according to the present embodiment is applied. As described above, the drive control according to the present embodiment performs the acceleration (required drive wheel acceleration) a1 required for the drive wheels provided in the vehicle 1 and the road surface GL where the drive wheels 2 contact the drive wheels 2 of the vehicle 1. From the upper limit acceleration (limit driving wheel acceleration) a2 that can be generated by the driving wheel 2 from the friction coefficient μ between the driving wheel 2 and the driving wheel 2, an acceleration (a possible driving wheel acceleration) a3 that can be generated by the driving wheel 2 is obtained. Then, the braking / driving force Fd of the driving wheel 2 is obtained from the possible driving wheel acceleration a3 and the acceleration (actual driving wheel acceleration) ar currently generated by the driving wheel 2, and the driving wheel 2 is driven. In the following, one of the plurality of drive wheels 2 provided in the vehicle 1 shown in FIG. 1 will be described.

The requested driving wheel acceleration a1 is an acceleration requested by the driver of the vehicle 1 shown in FIG. The required driving wheel acceleration a1 can be obtained by the equation (1) based on the driver required torque Td.
a1 = Td / (r × m × g) (1)
Here, r is a dynamic load radius of the driving wheel 2, m is a load of the vehicle 1 supported by the driving wheel 2, and g is a gravitational acceleration. The driver request torque Td is a request torque for one drive wheel 2. Note that m_fl is the load that the left front wheel 2fl of the vehicle 1 shown in FIG. The load M of the vehicle 1 supported by the driving wheels 2 is m_fl + m_fr + m_rl + m_rr.

The limit driving wheel acceleration a2 can be obtained based on information (μ information) of the friction coefficient μ between the driving wheel 2 provided in the vehicle 1 shown in FIG. 1 and the road surface GL. Here, the friction coefficient μ can be obtained by Expression (2). Then, the limit drive wheel acceleration a2 can be obtained by the equation (3) using the friction coefficient μ obtained by the equation (2) and the load m of the vehicle 1 supported by the drive wheel 2.
μ = Ftrc / (m × g) (2)
a2 = μ × g = Ftrc / m (3)
Ftrc = (T × RD−Iv × a) / r (4)
Here, Ftrc is a road surface reaction force. RD is a reduction ratio. The road surface reaction force Ftrc is a force by which the road surface GL pushes the driving wheel 2 and has the same magnitude and opposite direction as the braking / driving force Fd of the driving wheel 2. The road surface reaction force Ftrc can be obtained by Expression (4), and changes in the same manner as the friction coefficient μ as shown in FIG.

  As can be seen from equation (4), the driving wheel acceleration a can be obtained by differentiating dω / dt, that is, the rotational angular velocity ω (rad / sec.) Of the driving wheel 2 with respect to time t. Thus, in this embodiment, the driving wheel acceleration a is the rotational angular acceleration. For example, in the vehicle 1 according to the present embodiment, the drive system inertia Iv is the inertia of all structures related to power transmission existing between the rotor of the electric motor 10 and the drive wheels 2.

The possible drive wheel acceleration a3 is the smaller of the required drive wheel acceleration a1 or the limit drive wheel acceleration a2 as shown in the equation (5). Note that min (a1, a2) means that the smaller one of a1 and a2 is selected.
a3 = min (a1, a2) (5)

The torque correction value Tc of the driving wheel 2 is obtained from the equation (6) using the possible driving wheel acceleration a3 obtained from the equation (5) and the actual driving wheel acceleration ar. And torque command value Ts with respect to the electric motor 10 which supplies motive power to the drive wheel 2 is correct | amended with the torque correction value Tc calculated | required by Formula (6). A correction value (torque correction command value) Ts_c of the torque command value Ts is expressed by Expression (7). The braking / driving force Fd of the drive wheel 2 is obtained from equation (8) using the torque correction command value Ts_c obtained from equation (7). Here, It is the inertia of the drive wheel 2.
Tc = (a3-ar) × It (6)
Ts_c = Ts + Tc (7)
Fd = Ts_c × r (8)

  By controlling the braking / driving force of the driving wheel 2 in such a manner, as shown in FIG. 6A, before the friction coefficient μ between the driving wheel 2 and the road surface GL becomes the maximum friction coefficient μmax, Control for suppressing slip of the drive wheel 2 can be executed. As a result, it takes time until the driving force of the driving wheels 2 actually decreases due to a delay due to the sampling cycle of the rotational speed Vw of the driving wheels 2, a delay in communication of the ECU 50, a delay due to a twist in the driving system of the vehicle 1, or the like. Even if necessary, an excessive slip of the drive wheel 2 can be suppressed. Thus, according to this embodiment, the slip which generate | occur | produces in the driving wheel 2 can be suppressed at an earlier stage, and the behavior of the vehicle can be stabilized at an early stage.

  Further, by controlling the braking / driving force of the driving wheel 2 by the above-described method, the change in the rotational speed Vw of the driving wheel 2 becomes gradual as indicated by A in FIG. Excessive slip can be suppressed. As a result, when the slip of the drive wheel 2 is suppressed, an excessive decrease in the torque applied to the drive wheel 2 can be suppressed, so that impact and vibration when suppressing the slip of the drive wheel 2 can be suppressed. Further, as indicated by A in FIG. 6A, since the change in the slip ratio slip of the drive wheel 2 near the maximum friction coefficient μmax becomes gentle, the maximum friction coefficient μmax, that is, the peak of the road surface reaction force Ftrc is obtained. Accurately grasp.

  FIG. 7 is an explanatory diagram illustrating a configuration example of the drive control device according to the present embodiment. As shown in FIG. 7, the drive 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 drive 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 drive control apparatus 30 can utilize the control function with respect to the traveling apparatus 100 grade | etc. With which ECU50 is provided.

  The drive control device 30 includes a control condition determination unit 31, an acceleration calculation unit 32, a possible acceleration calculation unit 33, and a braking / driving force calculation unit 34. These are the parts that execute the slip suppression control according to the present embodiment. In the present embodiment, the drive control device 30 is configured as a part of the CPU 50p configuring the ECU 50.

The control condition determination unit 31, the acceleration calculation unit 32, the possible acceleration calculation unit 33, and the braking / driving force calculation unit 34 of the drive control device 30 are a bus 54 ₁ , a bus 54 ₂ , an input port 55, and an output port. 56 is connected. As a result, the control condition determination unit 31, the acceleration calculation unit 32, and the possible acceleration calculation unit 33 constituting the drive control device 30 can exchange control data with each other and issue commands to one side. Composed.

Further, the drive control device 30 provided in the CPU 50p, and the storage unit 50m, are connected via a bus 54 _3. As a result, the drive control device 30 can acquire the operation control data of the traveling device 100 included in the ECU 50 and use it. Moreover, the drive control apparatus 30 can interrupt the slip suppression control which concerns on this embodiment in the driving control routine with which ECU50 is equipped beforehand.

  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 yaw rate sensor 43, a longitudinal acceleration sensor 44, a lateral direction. The direction acceleration sensor 45 and other sensors for acquiring information necessary for operation control of the traveling device 100 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 | running 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 the present 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 the present 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 such a configuration, based on the output signals from the sensors, the CPU 50p of the ECU 50 controls the braking / driving forces of the left front motor 10fl, the right front motor 10fr, the left rear motor 10rl, and the right rear motor 10rr. Can do.

  The storage unit 50m stores a computer program including a processing procedure of slip suppression control according to the present embodiment, a control map, a data map used for slip suppression control according to the present 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 drive control processing procedure according to the present embodiment in combination with a computer program already recorded in the CPU 50p. In addition, the drive control device 30 uses functions of the control condition determination unit 31, the acceleration calculation unit 32, the possible acceleration calculation unit 33, and the braking / driving force calculation unit 34 using dedicated hardware instead of the computer program. It may be realized. Next, drive control according to the present embodiment will be described. The drive control according to the present embodiment can be realized by the drive control device 30 described above.

  FIG. 8 is a flowchart showing the procedure of drive control according to the present embodiment. In step S101, the control condition determination unit 31 of the drive control device 30 shown in FIG. 7 determines whether or not information on the friction coefficient μ exists. The μ information is a friction coefficient between the drive wheel 2 and the road surface GL obtained by the above-described equation (2), and is obtained from the road surface reaction force Ftrc obtained when the drive wheel 2 slips. Stored in the storage unit 50m. When slip occurs in the drive wheel 2, the μ information is updated to the latest friction coefficient μ obtained from the road surface reaction force Ftrc obtained at that time. For example, the μ information may be stored in the storage unit 50m as an initial value of the coefficient of friction μ between the drive wheel 2 and the dry road surface.

  When it is determined Yes in step S101, that is, when the control condition determination unit 31 of the drive control device 30 determines that there is μ information, the process proceeds to step S102, and the acceleration calculation unit 32 of the drive control device 30 The required drive wheel acceleration a1 and the limit drive wheel acceleration a2 are obtained using the equations (1) and (3). If it is determined No in step S101, that is, if the control condition determination unit 31 of the drive control device 30 determines that there is no μ information, the process proceeds to step S103, where the acceleration calculation unit 32 of the drive control device 30 Only the required drive wheel acceleration a1 is obtained using the above-described equation (1). In other words, the driver's request is given priority.

  When the required drive wheel acceleration a1 and the limit drive wheel acceleration a2 or the required drive wheel acceleration a1 are obtained, the process proceeds to step S104. In step S104, the possible acceleration calculation unit 33 of the drive control device 30 obtains the possible drive wheel acceleration a3 using Expression (5). In step S105, the control condition determination unit 31 compares the possible driving wheel acceleration a3 with the actual driving wheel acceleration ar.

  When it is determined Yes in step S105, that is, when the control condition determination unit 31 determines that a3 <ar, it can be determined that slip occurs in the drive wheels 2. In this case, the braking / driving force calculation unit 34 obtains the torque correction value Tc using Equation (6) in step S106. In step S107, the braking / driving force calculation unit 34 corrects the torque command value Ts at the current time for the electric motor 10 with the torque correction value Tc obtained in step S106 by using equation (8), thereby correcting the torque. A command value Ts_c is obtained. Thereafter, the braking / driving force calculation unit 34 outputs the torque correction command value Ts_c obtained in step S107 to the inverter 6 shown in FIGS. 1 and 7, and drives the electric motor 10 in step S108.

  When it is determined No in step S105, that is, when the control condition determination unit 31 determines that a3 ≧ ar, it can be determined that no slip occurs in the drive wheels 2. In this case, the process proceeds to step S109. In step S109, the braking / driving force calculation unit 34 maintains the current control conditions, and drives the electric motor 10 in step S108. That is, by driving the electric motor 10 with the current torque command value Ts, the driving torque applied to the driving wheels 2 at the current time is maintained. Thereby, the behavior change of the vehicle 1 due to the change of the braking / driving force can be suppressed.

  For example, when the vehicle 1 gets over a step, the possible drive wheel acceleration a3 is larger than the actual drive wheel acceleration ar. In such a case, when the torque correction value Tc is obtained using the possible drive wheel acceleration a3 and the current torque command value Ts is corrected, the torque correction command value Ts_c becomes larger than the current torque command value Ts. As a result, there is a risk that a shock may occur when getting over the step. For this reason, when a3> ar, the electric motor 10 is driven with the current torque command value Ts. Thereby, the behavior change of the vehicle 1 due to the change of the braking / driving force can be suppressed.

  For example, when the vehicle 1 travels while the hand brake of the vehicle 1 is applied, or the vehicle 1 travels while dragging the brake, the generated drive wheel acceleration a3 is the actual drive wheel acceleration ar. Bigger than. In such a case, when the torque correction value Tc is obtained using the possible drive wheel acceleration a3 and the current torque command value Ts is corrected, the torque correction command value Ts_c becomes larger than the current torque command value Ts. As a result, the brake may be overheated. Therefore, when a3> ar, the electric motor 10 is driven with the current torque command value Ts. As a result, overheating of the brake can be suppressed.

  If the possible driving wheel acceleration a3 in step S105 is not compared with the actual driving wheel acceleration ar, and the possible driving wheel acceleration a3 is obtained in step S104, the torque correction value Tc is obtained using this to obtain the current torque correction value Tc. The torque command value Ts at may be corrected with the torque correction value Tc.

  As described above, in the present embodiment, the upper limit of the drive wheel that can be generated from the required drive wheel acceleration required for the drive wheel provided in the vehicle and the coefficient of friction between the drive wheel of the vehicle and the road surface in contact with the drive wheel. The driving wheel acceleration is obtained, and the possible driving wheel acceleration that can be generated by the driving wheel of the vehicle is obtained based on the obtained requested driving wheel acceleration and the limit driving wheel acceleration. Then, based on the obtained drive wheel acceleration that can be generated and the acceleration that the drive wheel is currently generating, the drive torque of the drive wheel is obtained. As a result, the driving torque of the driving wheel provided in the vehicle is obtained in consideration of the required driving wheel acceleration and the limit driving wheel acceleration, so that the delay due to the sampling period of the wheel speed, the communication delay of the ECU, or the driving system of the vehicle Even if it takes time until the driving force of the driving wheel actually decreases due to a delay due to torsion or the like, an excessive slip of the driving wheel can be suppressed. As a result, the slip generated on the drive wheels can be suppressed at an earlier stage, and the behavior of the vehicle can be stabilized at an early stage. In addition, the driving wheels can be driven in the vicinity of the peak value of the road surface reaction force while respecting the driver's intention.

  As described above, the drive control device according to the present invention is useful for suppressing the slip of the drive wheel, and is particularly suitable for suppressing the slip generated in the drive wheel at an earlier stage.

It is the schematic which shows the structure of a vehicle provided with the traveling apparatus which concerns on this embodiment. It is a key map explaining wheel speed, road surface reaction force, etc. It is explanatory drawing which shows the relationship between the friction coefficient between a wheel and a road surface, and a slip ratio. It is explanatory drawing which shows the time change of a vehicle speed or a wheel speed. It is a control block diagram of drive control concerning this embodiment. It is a conceptual diagram which shows the relationship between a road surface reaction force and a slip ratio. It is explanatory drawing which shows the relationship between the friction coefficient between a wheel and a road surface, and a slip ratio. It is explanatory drawing which shows the time change of the vehicle speed or wheel speed at the time of applying the drive control which concerns on this embodiment. It is explanatory drawing which shows the structural example of the drive control apparatus which concerns on this embodiment. It is a flowchart which shows the procedure of the drive control which concerns on this embodiment.

Explanation of symbols

1 Vehicle 2 Drive Wheel 4 Handle 5 Accelerator 6 Inverter 7 Car Power Supply
10 Electric motor
DESCRIPTION OF SYMBOLS 30 Drive control apparatus 31 Control condition determination part 32 Acceleration calculating part 33 Possible acceleration calculating part 34 Braking / driving force calculating part 40 Resolver 41 Accelerator opening degree sensor 42 Steering angle sensor 43 Yaw rate sensor 44 Longitudinal direction acceleration sensor 45 Lateral direction acceleration sensor 50 ECU
100 travel device

Claims (2)

The upper limit drive wheel acceleration that can be generated by the drive wheel from the required drive wheel acceleration required for the drive wheel provided in the vehicle and the friction coefficient between the drive wheel of the vehicle and the road surface in contact with the drive wheel. An acceleration calculation unit to be obtained;
Based on the required driving wheel acceleration and the limit driving wheel acceleration, a possible acceleration calculating unit that obtains a possible driving wheel acceleration that can be generated by the driving wheel;
A braking / driving force calculation unit for obtaining a driving torque to be applied to the driving wheel based on the possible driving wheel acceleration and an acceleration generated by the driving wheel at the present time;
A drive control device comprising: The braking / driving force calculator is
2. The drive torque applied to the drive wheel at the current time is maintained when the possible drive wheel acceleration is greater than the acceleration that the drive wheel is currently generating. Drive control device.

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