JP2007244094A - Rotating torque controller for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating torque controller for a vehicle wherein the rotating torque of driving wheels is optimally controlled without fail before the driving wheels slip and the occurrence of a slip due to change in ground contact force at the driving wheels can be quickly prevented without fail. <P>SOLUTION: The rotating torque controller includes: first acceleration detecting means 19L, 19R, 20L, 20R for detecting acceleration in the vertical direction under the springs of a suspension system 41; second acceleration detecting means 21L, 21R, 22L, 22R for detecting acceleration in the vertical direction above the springs of the suspension system; a computation unit 31 that computes the road surface contact force of the wheels based on vertical acceleration from the first acceleration detecting means and vertical acceleration from the second acceleration detecting means; an estimation unit 32 that estimates the state of a slip due to change in the ground contact force of a wheel based on the values of road surface contact force; and a rotating torque determination unit 33 that determines the rotating torque of a driving force generation unit according to an estimation value associated with the state of the slip. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle rotational torque control device, and more particularly to a vehicle rotational torque that predicts and prevents slip occurrence due to a grounding force phenomenon at each wheel in a four-wheel vehicle or the like in which each wheel is individually motor-driven. The present invention relates to a control device.

2. Description of the Related Art Conventionally, slip prevention control for preventing a slip state between a drive wheel and a road surface in an engine-driven four-wheel vehicle or the like is known. As a prior art of this anti-slip control, there is traction control in which a slip state (idling state) of a drive wheel is detected and the rotational torque of the drive wheel is automatically controlled (see Patent Document 1). According to this traction control, when the accelerator wheel is stepped on a slippery road surface and the drive wheel slips, the rotational torque applied from the engine to the drive wheel is reduced, or the brake device for the drive wheel is operated. This suppresses the slip state of the drive wheels. In traction control, a rotational speed sensor is attached to each driving wheel, the rotational speed of each driving wheel is detected by this rotational speed sensor, and the control computer overdrives the driving wheel based on the detected change information of the rotational speed. If it is determined, the rotational torque of the drive wheel is suppressed or the brake device is operated to suppress the state of the generated slip.
JP 2006-44647 A

  According to the slip prevention control of the drive wheel based on the traction control, it is determined whether or not the vehicle is in the slip state based on the change in the rotation speed of the drive wheel, and the slip state is suppressed when it is determined that the slip state is detected. The control which makes the rotation speed of the driving wheel for this appropriate is performed. For this reason, the traction control is based on the condition that a slip state has occurred between the drive wheel and the road surface, and the condition is that the slip always occurs on the drive wheel. That is, according to the conventional traction control, it has a characteristic of control after the occurrence of slip, and since it becomes post-control, a slight delay in control cannot be denied.

  Further, for example, in a motor-driven vehicle that is a four-wheel vehicle and each of the four wheels is a drive wheel that is individually driven by a motor, a slip state may occur for each wheel. In the anti-slip control of each wheel in such a motor-driven vehicle, in consideration of the speed of control, prior control based on predictive control is desirable.

  In view of the above problems, an object of the present invention is to optimally control the rotational torque of a drive wheel before the slip state occurs in the drive wheel, and to prevent the occurrence of the slip state in the drive wheel quickly and reliably. An object of the present invention is to provide a rotational torque control device for a vehicle that can perform the above.

  In order to achieve the above object, a vehicle rotational torque control apparatus according to the present invention is configured as follows.

  A rotational torque control device for a first vehicle (corresponding to claim 1) is a vehicle in which wheels are suspended from a vehicle body via a suspension device, and the rotational torque control device controls driving force generating means for generating rotational torque in the vehicle. The first acceleration detecting means for detecting the vertical acceleration related to the unsprung wheel of the suspension device, the second acceleration detecting means for detecting the vertical acceleration related to the vehicle body above the spring of the suspension device, Calculating means for calculating the road surface contact force of the wheel based on the vertical acceleration of the wheel output from the first acceleration detecting means and the vertical acceleration of the vehicle body output from the second acceleration detecting means; and the road surface calculated by the calculating means An estimation means for estimating the slip state of the wheel based on the value of the contact force, and a rotational torque determination for determining the rotational torque of the driving force generation means based on the estimated value related to the slip state estimated by the estimation means Configured and means.

  In the vehicle rotational torque control device described above, the road surface ground force at the wheel (drive wheel) is based on the vertical acceleration on the unsprung wheel of the suspension device and the vertical acceleration on the vehicle body on the spring side of the suspension device. Is calculated. The estimating means estimates the slip state of the wheel based on the road surface contact force value calculated by the calculating means. The rotational torque determining means determines the rotational torque of the driving force generating unit based on the estimated value related to the slip state estimated by the estimating means, and the wheel rotates with the determined rotational torque. As a result, the rotational torque of the wheel is optimally controlled before the slip state due to the change in grounding force at the driven wheel occurs, and the occurrence of the slip state of the wheel is surely prevented.

  In the above configuration, the rotational torque control device for the second motor-driven vehicle (corresponding to claim 2) is preferably measured by measuring a state quantity related to the resonance frequency from the vertical acceleration of the unsprung portion of the suspension device. It is characterized by comprising first measuring means for obtaining a value and second measuring means for obtaining a measured value by measuring a state quantity related to the resonance frequency from the vertical acceleration of the sprung portion of the suspension device.

  In the above configuration, the rotational torque control device for a third motor-driven vehicle (corresponding to claim 3) is preferably configured such that the calculation means includes a state quantity measurement value relating to a resonance frequency of the unsprung part and a resonance of the sprung part. A road surface contact force is calculated by setting a threshold value from the state quantity measurement value related to the frequency, and comparing the measured vertical acceleration of the wheel and the state quantity related to the frequency calculated from the vertical acceleration of the vehicle body and the threshold value. It is characterized by.

  The rotational torque control device for a fourth motor-driven vehicle (corresponding to claim 4) is preferably configured as described above, wherein the driving force generating means is a motor suspended on the vehicle body together with the wheels via the suspension device. It is characterized by.

  According to the present invention, for example, in a vehicle equipped with a wheel such as a motor drive, the road surface ground force of the wheel is estimated and calculated, the slip state of the wheel is estimated based on the calculated road surface ground force, and the estimated wheel slip Since the rotational torque of the wheel motor is determined based on the condition, the rotational torque of the drive motor is optimally controlled before the slip condition occurs due to a change in grounding force, and the occurrence of the slip condition on the wheel is reliably prevented in advance. can do. Thereby, the stable smooth driving | running | working of a vehicle is realizable.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Preferred embodiments (examples) of the invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a plan view showing a schematic configuration of, for example, a motor-driven vehicle provided with a rotational torque control device according to the present invention. In the present embodiment, the “motor-driven vehicle” means a vehicle having four wheels, for example, and each of the four vehicles is individually driven by a motor. However, the number of wheels driven by the motor is not limited to four. For example, the front two wheels or the rear two wheels may be used. The vehicle to which the rotational torque control device according to the present invention is applied is not limited to a motor-driven vehicle, and may be an engine-driven vehicle.

  The motor-driven vehicle 10 (hereinafter abbreviated as “vehicle 10”) has four wheels 14L, 14R, 15L, and 15R attached to the rotational drive shafts of the motors 12L, 12R, 13L, and 13R attached to the vehicle body 11, respectively. ing. The four wheels 14L, 14R, 15L, and 15R are individually driven by respective motors and function as drive wheels. Hereinafter, “wheels 14L, 14R, 15L, 15R” are referred to as “drive wheels 14L, 14R, 15L, 15R”. In FIG. 1, it is assumed that the upper end of the vehicle 10 is the front side.

  The four drive wheels 14L, 14R, 15L, and 15R are each attached to the vehicle body 11 via a suspension device not shown in FIG. The vehicle 10 includes a power drive unit (PDU) 16 that individually drives and controls the two motors 12L and 12R, and a power drive unit (PDU) 17 that individually drives and controls the two motors 13L and 13R. The vehicle 10 further includes an electronic control unit (ECU) 18 that controls the operations of the two power drive units 16 and 17. Further, acceleration sensors 19L, 19R, 20L, and 20R that detect vertical accelerations related to the unsprung wheels of the suspension device are attached to the four drive wheels 14L, 14R, 15L, and 15R, respectively. Further, four acceleration sensors 21L, 21R, 22L, and 22R for detecting vertical accelerations related to the vehicle body on the spring side of the suspension device are attached to the vehicle body 11 near the drive wheels 14L, 14R, 15L, and 15R, respectively. ing.

  FIG. 2 is a rear view of the periphery of the drive wheel 14L, with a part thereof in cross section. A drive wheel 14L is supported by a suspension device 41 with respect to the vehicle body 11 shown partially in cross section. The drive wheels 14L are installed on the road surface 51. The drive wheel 14 </ b> L receives a road surface contact force from the road surface 51 in a direction perpendicular to the road surface 51. The driving wheel 14L is given a rotational driving force by the motor 12L. The drive wheel 14L and the motor 12L are configured as a unit. The drive wheels 14 </ b> L and the motor 12 </ b> L are connected to the vehicle body 11 based on a link mechanism formed by the upper suspension arm 42 and the lower suspension arm 43 of the suspension device 41. Furthermore, the suspension device 41 includes, for example, a spring / cylinder adjustment unit 44 between the lower suspension arm 43 and the vehicle body 11.

  The acceleration sensor 19L that detects the vertical acceleration related to the drive wheel 14L on the unsprung side of the suspension device 41 is attached to, for example, the motor 12L. The acceleration sensor 21 </ b> L that detects vertical acceleration related to the vehicle body 11 on the spring side of the suspension device 41 is attached to the vehicle body 11.

  The above configuration is similarly provided for the remaining three drive wheels 14R, 15L, and 15R.

  The four drive wheels 14L, 14R, 15L, and 15R are individually driven independently by the motors 12L, 12R, 13L, and 13R and rotate. The motors 12L, 12R, 13L, and 13R are traveling AC motors, for example, and are driven and controlled by the power drive units 16 and 17. The power drive units 16 and 17 include inverters and have energy storages separately. This energy storage includes a fuel cell, a storage battery, and the like. The inverter converts a direct current from the energy storage into an alternating current and supplies the alternating current to the motors 12L, 12R, 13L, and 13R. Outputs to the motors 12L, 12R, 13L, and 13R are controlled by an inverter based on a command from the ECU 18.

  The ECU 18 includes, for example, a rotational speed detector 23 that detects the rotational speed of the motor, a brake hydraulic pressure detection unit 24 that detects the hydraulic pressure state of the brake device, and a side brake detection unit 25 that detects the operation / non-operation of the side brake. An accelerator operation amount detection unit 26 that detects an electric accelerator operation amount, a rotation direction detection unit 27 that detects the rotation direction of the motor, a motor current detection unit 28 that detects a motor current, and an output voltage of the inverter Signals are input from the inverter voltage detection unit 29 to detect, the four acceleration sensors 19L, 19R, 20L, and 20R, and the four acceleration sensors 21L, 21R, 22L, and 22R, respectively.

  In FIG. 1, the rotation number detector 23, the rotation direction detection unit 27, and the motor current detection unit 28 are shown as one block, but actually correspond to each of the four motors 12L, 12R, 13L, and 13R. And four each. Here, each block is shown as one block for simplification of illustration and explanation. In FIG. 1, the inverter voltage detection unit 29 is also shown as one block, but is actually provided for each inverter that drives the four motors 12L, 12R, 13L, and 13R.

  In the vehicle 10, first, when the start switch provided in the driver's seat is turned on by a key possessed by the driver, the ECU 18 and the power drive units 16 and 17 are started. In this state, when the side brake is deactivated, the ECU 18 detects that the side brake is not activated based on a signal from the side brake detection unit 25, and the motor can be driven. When the driver steps on the electric accelerator, a signal from the accelerator operation amount detector 26 is sent to the ECU 18 and a motor drive control signal corresponding to the accelerator operation amount is sent to the power drive units 16 and 17. The power drive units 16 and 17 supply currents corresponding to the motor drive control signals to the motors 12L, 12R, 13L, and 13R. Thereby, the motors 12L, 12R, 13L, 13R are rotationally driven. At that time, a signal from the motor current detection unit 28 is sent to the ECU 18 for feedback control, and the drive wheels 14L, 14R, 15L, 15R rotate stably, and the vehicle travels stably at a vehicle speed corresponding to the accelerator operation amount. To do.

  Further, when the vehicle 10 is traveling, a signal related to the vertical acceleration related to the wheels (the unsprung portion of the suspension device) from the four acceleration sensors 19L, 19R, 20L, and 20R, and the four acceleration sensors 21L and 21R. , 22L, 22R detects signals related to the vertical acceleration related to the vehicle body (upper spring portion of the suspension device). The ECU 18 calculates a road surface contact force on the drive wheel for each drive wheel based on signals related to the vertical acceleration by a calculation method to be described later, and the ground state of each drive wheel based on the calculated road surface contact force. (Slip state) is estimated, and the rotational torque of the motor corresponding to each drive wheel is determined based on the estimated value related to the estimated ground contact state. Thereafter, the ECU 10 sends a motor drive control signal to the power drive units 16 and 17 so that each motor rotates with the rotational torque determined for each motor. Accordingly, the motors 12L, 12R, 13L, and 13R rotate and drive the drive wheels 14L, 14R, 15L, and 15R, respectively, with a rotational torque that does not cause the tires to slip.

  As described above, in the vehicle 10 in which the drive wheels 14L, 14R, 15L, and 15R are individually motor-driven, the vertical acceleration of the lower spring portion and the vertical acceleration of the upper spring portion of the suspension device are used for each drive wheel. By calculating the road surface contact force in advance, pre-control is performed before a slip occurs due to a change in the contact force, thereby quickly and optimally preventing the occurrence of a slip state of each drive wheel, that is, the occurrence of a tire slipping state in advance.

  FIG. 3 is a block diagram showing the overall configuration of the control system. A signal for grasping the motion status of the vehicle 10 is input to the ECU 18 by CAN (Controller Area Network) communication 30. As described above, these signals are a signal from the rotational speed detector 23 that detects the rotational speed of the motor, a signal from the brake hydraulic pressure detection unit 24 that detects the brake hydraulic pressure, and a side that detects the operation / non-operation of the side brake. A signal from the brake detection unit 25, a signal from the accelerator operation amount detection unit 26 that detects the electric accelerator operation amount, a signal from the actual rotation direction detection unit 27 that detects the actual rotation direction of the motor, and a motor current are detected. A signal from the motor current detection unit 28 and a signal from the inverter voltage detection unit 29 that detects the output voltage of the inverter.

  Further, the ECU 18 has signals from four acceleration sensors 19L, 19R, 20L, and 20R that detect the unsprung vertical acceleration and four acceleration sensors 21L, 21R, 22L, and 22R that detect the vertical acceleration on the spring. The signal from is input.

  The ECU 18 according to the present embodiment includes a road surface contact force calculation unit 31, a slip state estimation unit 32, and a rotational torque determination unit 33 as its main functions.

  The ECU 18 determines the road surface contact force calculation unit 31 for each driving wheel based on the signals related to the vertical acceleration from the four acceleration sensors 19L, 19R, 20L, and 20R and the four acceleration sensors 21L, 21R, 22L, and 22R. Based on the following calculation method, the road surface contact force is calculated. The next slip state estimation unit 32 estimates a slip state, that is, a ground contact state that may occur for each drive wheel, based on the road surface contact force calculated by the road surface contact force calculation unit 31, and calculates an estimated value. The rotational torque determination unit 33 determines the rotational torque of the corresponding motor for each drive wheel based on the calculated estimated slip state. The value of the rotational torque of each drive wheel determined by the rotational torque determination unit 33 is sent to the PDUs 16 and 17 as a motor drive control signal. Thereby, each of the motors 12L, 12R, 13L, and 13R gives rotational torque to the drive wheels with a torque that does not cause the tires of the corresponding drive wheels to slip. With this control, for each of the drive wheels 14L, 14R, 15L, and 15R, the ground contact state is estimated individually from the calculated value of the road surface contact force, and the occurrence of a slip state due to a change in the contact force is estimated and predicted in advance. Based on this, it is prevented in advance that a slip state occurs in each drive wheel.

  Next, a road surface contact force calculation method in the road surface contact force calculation unit 31 of the ECU 18 will be described. In this calculation method, a two-degree-of-freedom base model is used.

FIG. 4 shows a two-degree-of-freedom base model. In the model of FIG.
M2: Sprung mass M1: Unsprung mass Z2: Sprung coordinates (coordinates in the height direction perpendicular to the road surface (51))
Z1: Unsprung coordinates (coordinates in the height direction perpendicular to the road surface (51))
Z0: coordinates of the contact point between the road surface and the drive wheel (coordinates in the height direction perpendicular to the road surface (51))
K1: Spring constant of tire (drive wheel) K2: Spring constant of suspension spring C1: First damping constant C2: Second damping constant

  The equations of motion for the sprung mass M2 and the unsprung mass M1 are given by the following equations (Equation 1) and (Equation 2), respectively. However, in the formula, the mark “*” represents the first derivative, and the mark “**” represents the second derivative.

(Equation 1)
M1 * Z1 ^** + K1 * (Z1-Z0) + C1 ^* (Z1 ^* -Z0 ^* )-K2 ^* (Z2-Z1) -C2 ^* (Z2 ^* -Z1 ^* ) = 0

(Equation 2)
M2 · Z2 ^** + K2 · (Z2−Z1) + C2 · (Z2 ^* −Z1 ^* ) = 0

  Therefore, the road surface contact force W is given by the following equation (Equation 3).

(Equation 3)
W = -K1. (Z1-Z0) + C1. (Z1 ^* -Z0 ^* )
= M1 * Z1 ^**- K2 * (Z2-Z1) -C2 ^* (Z2 ^* -Z1 ^* )
= M1 / Z1 ^** + M2 / Z2 ^**

  As described above, the road surface contact force W is obtained as the sum of the inertial force of the sprung portion of the suspension device 41 and the inertial force of the unsprung portion.

  The above-mentioned sprung mass M2 and unsprung mass M1 can also be obtained from, for example, the peak frequency and peak value of the Fourier spectrum of the waveform of vertical acceleration obtained by vehicle body measurement.

  In the road surface contact force calculation unit 31 of the ECU 18 shown in FIG. 3, a calculation program based on the above calculation method is prepared, and a calculation program for obtaining the peak frequency and peak value from the measured vertical acceleration is also prepared. . By these calculation programs, calculation for obtaining the road surface contact force is performed.

  The road surface contact force calculation unit 31 outputs the road surface contact force W based on the resonance frequency calculated from the vertical acceleration from the acceleration sensor. In the slip state estimation unit 32, the road surface contact force W is compared with the vehicle axle weight as a threshold value, and whether the road surface contact force W is smaller than the threshold value determines whether a ground state, that is, a slip state occurs. Estimate. The rotational torque determination unit 33 determines the rotational torque of the motor based on the estimated slip state, and controls the rotational torque of the motor as described above.

  As described above, in this embodiment, the road surface contact force W is estimated based on the vertical acceleration of the unsprung part and the vertical acceleration of the sprung part, and the presence / absence of the occurrence of a slip state is estimated. Since the rotational torque of 12L, 12R, 13L, 13R is determined and the rotation of each drive wheel 14L, 14R, 15L, 15R is controlled, the occurrence of a slip state due to the contact force change in each drive wheel is prevented in advance. can do. Thereby, stable and smooth travel can be performed.

  Although the present embodiment has been described using a motor provided outside a conventional wheel as a motor, the present invention is not limited to this and can be applied to an in-wheel motor.

  Furthermore, the rotational torque control apparatus according to the present invention can be applied to, for example, an engine-driven vehicle in which engine driving force is distributed by a differential gear and supplied to each driving wheel. Also in this case, the rotational torque of each drive wheel is adjusted according to the road surface contact force.

  The configurations described in the above embodiments are merely shown to the extent that the present invention can be understood and implemented. Therefore, the present invention is not limited to the described embodiments, and can be variously modified without departing from the scope of the technical idea shown in the claims.

  The present invention is used as a control device for preventing in advance a slip state of a drive wheel due to a change in grounding force in a vehicle such as a motor drive.

It is a top view which shows schematic structure of the motor drive vehicle provided with the rotational torque control apparatus which concerns on this invention. It is the figure which looked at the rear side of the driving wheel on the left side of the front wheel, with a part of its peripheral part in cross section. It is a block diagram which shows the structure of a control system. It is a figure which shows a 2 degree-of-freedom base model.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vehicle 11 Car body 12L, 12R Motor 13L, 13R Motor 14L, 14R Drive wheel 15L, 15R Drive wheel 16, 17 Power drive unit (PDU)
18 Electronic control unit (ECU)
19L, 19R Acceleration sensor 20L, 20R Acceleration sensor 21L, 21R Acceleration sensor 22L, 22R Acceleration sensor 23L, 23R Acceleration sensor 31 Road surface contact force calculation unit 32 Slip state estimation unit 33 Rotation torque determination unit

Claims (4)

A rotational torque control device for controlling driving force generating means for generating rotational torque in a vehicle in which wheels are suspended from a vehicle body via a suspension device,
First acceleration detecting means for detecting vertical acceleration relating to the wheel below the spring of the suspension device;
Second acceleration detecting means for detecting vertical acceleration related to the vehicle body on the spring side of the suspension device;
Calculating means for calculating road contact force of the wheel based on the vertical acceleration of the wheel output from the first acceleration detecting means and the vertical acceleration of the vehicle body output from the second acceleration detecting means; ,
Estimating means for estimating a slip state of the wheel based on a value of the road surface contact force calculated by the calculating means;
Rotational torque determining means for determining the rotational torque of the driving force generating means based on an estimated value related to the slip state estimated by the estimating means;
A rotational torque control device for a vehicle, comprising: First measurement means for measuring a state quantity related to a resonance frequency from a vertical acceleration of an unsprung portion of the suspension device to obtain a measurement value;
Second measurement means for measuring a state quantity related to a resonance frequency from a vertical acceleration of a sprung portion of the suspension device to obtain a measurement value;
The rotational torque control device for a vehicle according to claim 1, comprising:   The calculation means sets a threshold value from the state quantity measurement value related to the resonance frequency of the unsprung part and the state quantity measurement value related to the resonance frequency of the unsprung part, and measures the vertical acceleration of the wheel, the vehicle body 3. The vehicle rotational torque control apparatus according to claim 2, wherein the road surface contact force is calculated by comparing a state quantity relating to a frequency calculated from the vertical acceleration of the vehicle and the threshold value. 4. The vehicle rotational torque control device according to claim 1, wherein the driving force generating means is a motor suspended on a vehicle body together with the wheels via a suspension device. 5.

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