JP2016028913A - Vehicle pitching vibration control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the pitching vibration of a vehicle just before the vehicle is stopped without using a vehicle model.SOLUTION: A vehicle pitching vibration control device A including right and left inverter-motors 5 and 6 generating a regenerative brake force in a drive source, and reducing the total brake force of an entire vehicle just before the vehicle is stopped during regenerative braking, thereby damping vibration at a time of stopping the vehicle. This pitching vibration control device A comprises: a smooth-stop-starting-timing computing unit 10e; a smooth-stop-target-value computing unit 10c setting a final target value of a motor brake/drive force in a process of reducing the total brake force; and a smooth-stop-control-waveform computing unit 10d reducing the regenerative brake force at a predetermined down grade when a vehicle velocity reaches a torque reduction start vehicle velocity V2 during the regenerative braking. The smooth-stop-starting-timing computing unit 10e sets the torque-reduction-start vehicle velocity V2 for setting a vehicle longitudinal acceleration to be equal to or lower than a predetermined allowable value when the vehicle changes from a deceleration state to a zero velocity state, on the basis of the regenerative brake force during the regenerative braking, the final target value of the motor drive/brake force, and the predetermined down grade.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle longitudinal vibration control device that prevents a shock (so-called “cuckling brake”) when a vehicle stops.

  Conventionally, by approximating a vehicle with a two-degree-of-freedom spring model and performing F / F control (feed-forward control) on the approximate model, the pitching motion during acceleration / deceleration is controlled to suppress vibrations just before the vehicle stops. A braking / driving force control device is known (see, for example, Patent Document 1).

JP 2006-264628 A

  However, in the conventional device, the state of the actual vehicle to be controlled changes when the hydraulic brake intervenes, the road surface gradient changes, or the number of passengers increases. For this reason, when the state of the actual vehicle changes, there is a problem that the deviation (modeling error) between the preset approximate model and the actual control target increases, and the longitudinal vibration just before the vehicle stops cannot be suppressed.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a vehicle longitudinal vibration control device capable of suppressing longitudinal vibration immediately before the vehicle stops without using a vehicle model.

In order to achieve the above object, the present invention has a motor that generates a regenerative braking force in a drive source, and reduces the total braking force of the entire vehicle immediately before stopping the vehicle during the regenerative braking, so that when the vehicle stops. Vibration in at least one of the front-rear direction and the pitching direction of the vehicle body is reduced.
The vehicle longitudinal vibration control apparatus includes torque reduction start vehicle speed setting means, final target value setting means, and motor control means.
The torque decrease start vehicle speed setting means sets a torque decrease start vehicle speed that starts a decrease in the total braking force immediately before the vehicle stops.
The final target value setting means sets the final target value of the motor braking / driving force in the step of reducing the total braking force to a sum of forces acting in the vehicle longitudinal direction at a timing when the vehicle shifts from the deceleration state to the vehicle speed of zero or less. Set the value to.
When the vehicle speed reaches the torque reduction start vehicle speed during regenerative braking, the motor control means reduces the regenerative braking force with a predetermined decreasing gradient that suppresses the resonance of the vehicle, thereby reducing the total braking force with the decreasing gradient.
The torque reduction start vehicle speed setting means sets the torque reduction start vehicle speed that makes the vehicle longitudinal acceleration when the vehicle shifts from the deceleration state to the vehicle speed zero or less, a regenerative braking force during regenerative braking and a motor braking / driving force. Is set based on the final target value and a predetermined decrease gradient.

Therefore, by reducing the total braking force of the entire vehicle immediately before stopping the vehicle during braking and smoothly reducing the deceleration of the entire vehicle, at least one of the front-rear direction and the pitching direction of the vehicle body when the vehicle is stopped The vibration in the direction is reduced.
That is, the actual deceleration changes even when the regenerative braking force is constant, when the hydraulic brake intervenes, the road surface gradient changes, the occupants increase, or the vehicle state changes. For this reason, first, the final target value of the braking / driving force of the motor in the step of reducing the total braking force is less than or equal to a predetermined value at the sum of the forces acting on the vehicle in the front-rear direction when the vehicle shifts from the deceleration state to the vehicle speed zero. Is set to the value Thus, it is assumed that the vehicle is almost stopped just before the vehicle stops. By determining the vehicle speed at which torque reduction starts based on the regenerative braking force during regenerative braking, the decreasing gradient that suppresses vehicle resonance, and the final target value of the motor braking / driving force, vibration is reliably suppressed immediately before stopping. In addition, the vehicle can be brought into a substantially stopped state at the end of the process of reducing the total braking force.
As a result, regardless of changes in the vehicle state, the vehicle can be stopped by suppressing the vehicle longitudinal vibration just before the vehicle stops, and the vibration suppression control just before stopping can be performed without using the vehicle model.

1 is an overall system diagram showing an in-wheel motor electric vehicle to which a longitudinal vibration control device of Embodiment 1 is applied. 1 is a block diagram illustrating a control system configuration of a longitudinal vibration control device for a vehicle according to a first embodiment. It is a flowchart which shows the flow of the longitudinal vibration control process at the time of a stop performed with the vehicle control module and brake controller of the longitudinal vibration control apparatus of Example 1. FIG. 6 is a time chart showing a setting operation of a torque reduction start vehicle speed for starting a reduction of the total braking force on a flat road in the longitudinal vibration control apparatus of the first embodiment. 3 is a time chart showing a setting operation of a torque reduction start vehicle speed for starting a decrease in total braking force on an uphill in the longitudinal vibration control apparatus of the first embodiment. 6 is a time chart illustrating a setting operation of a torque reduction start vehicle speed for starting a decrease in total braking force on a downhill in the longitudinal vibration control apparatus of the first embodiment. It is a map figure which shows an example of the torque reduction start vehicle speed map used for the setting of the torque reduction start vehicle speed in the longitudinal vibration control apparatus of Example 1. FIG. It is a contrast characteristic figure which shows the vehicle speed characteristic and motor torque characteristic by the presence or absence of F / B control from the torque reduction start vehicle speed in the in-wheel motor electric vehicle carrying the longitudinal vibration control apparatus of Example 1. FIG. It is a contrast characteristic figure which shows the vehicle speed characteristic by the presence or absence of F / B control from the vehicle speed just before a stop in the in-wheel motor electric vehicle carrying the longitudinal vibration control apparatus of Example 1, and a motor torque characteristic. Brake pedal depression force, vehicle deceleration, regenerative torque, hydraulic brake, gradient / hydraulic estimation when a flat road is stopped by a brake pedal depression force of 0.15 G in the in-wheel motor electric vehicle equipped with the longitudinal vibration control device of the first embodiment It is a time chart which shows each characteristic. Brake pedal depression force, vehicle deceleration, regenerative torque, hydraulic brake, gradient / hydraulic estimation when an in-wheel motor electric vehicle equipped with the longitudinal vibration control device of Embodiment 1 is stopped on a flat road with a brake pedal depression force of 0.25G It is a time chart which shows each characteristic. Brake pedal depression force, vehicle deceleration, regenerative torque, hydraulic brake, gradient / hydraulic pressure when the 5% downhill road is stopped with a brake pedal depression force of 0.25G in the in-wheel motor electric vehicle equipped with the longitudinal vibration control device of Example 1 It is a time chart which shows each characteristic of presumption. It is a contrast characteristic figure which shows the torque input (deceleration) by the presence or absence of smooth stop control, vehicle transfer function, and vehicle vibration at the time of a stop with the in-wheel motor electric vehicle carrying the longitudinal vibration control apparatus of Example 1. FIG. It is a contrast characteristic figure which shows the vehicle speed and motor torque by the presence or absence of smooth stop control in the in-wheel motor electric vehicle carrying the longitudinal vibration control apparatus of Example 1. FIG. It is an effect confirmation figure which shows each characteristic of the vehicle speed, motor torque, and vehicle front-back G by smooth stop control with the in-wheel motor electric vehicle carrying the front-back vibration control apparatus of Example 1. FIG.

  Hereinafter, the best mode for realizing a longitudinal vibration control device for a vehicle according to the present invention will be described based on a first embodiment shown in the drawings.

First, the configuration will be described.
The configuration of the longitudinal vibration control device A of the in-wheel motor electric vehicle (an example of a vehicle) in the first embodiment is described as follows: [Overall system configuration], [Block configuration of the parked longitudinal vibration control system], ] Are described separately.

[Overall system configuration]
FIG. 1 shows an in-wheel motor electric vehicle to which the longitudinal vibration control device A of the first embodiment is applied. The overall system configuration will be described below with reference to FIG.

  In the longitudinal vibration control device A of the first embodiment, the left and right front wheels 1 and 2 are driven wheels, the left and right rear wheels 3 and 4 are in-wheel motor drive wheels, and the torques of the left and right rear wheels 3 and 4 that are drive wheels are independent. It is applied to an in-wheel motor electric vehicle based on a rear wheel drive that is controlled by the motor.

  As shown in FIG. 1, the front-rear vibration control device A includes a left inverter & motor 5, a right inverter & motor 6, a left motor controller 7, a right motor controller 8, a battery 9 as a motor control system. And a vehicle control module 10. As a hydraulic brake control system, a brake operation mechanism 11, a hydraulic actuator 12, a left front wheel wheel cylinder 13, a right front wheel wheel cylinder 14, a left rear wheel wheel cylinder 15, a right rear wheel wheel cylinder 16, and a brake controller 17 And.

  The left inverter & motor 5 and the right inverter & motor 6 have a unit configuration in which an inverter and a motor are combined. The left inverter & motor 5 and the right inverter & motor 6 constitute an in-wheel motor by being incorporated in the left and right rear wheels 3 and 4 respectively. At the time of power running, in accordance with motor drive commands from the left and right motor controllers 7 and 8, the DC power from the battery 9 is converted into three-phase AC by an inverter to drive the left and right motors. During regeneration, in response to motor regeneration commands from the left and right motor controllers 7 and 8, motor energy is generated by receiving rotational energy from the left and right rear wheels 3 and 4, and a three-phase AC generated current is converted to direct current by an inverter. To charge.

  The vehicle control module 10 outputs a motor drive command to the left and right motor controllers 7 and 8 when a motor drive is requested, and outputs a motor regeneration command to the left and right motor controllers 7 and 8 when a motor regeneration is requested. The vehicle control module 10 receives information from an accelerator opening sensor 18, a vehicle speed sensor 19, a resolver 20, a master cylinder pressure sensor 21, etc., and bidirectionally communicates with the brake controller 17 via a CAN communication line 22. Information exchange is possible. In addition to the drive / regenerative control configuration for the left and right motor controllers 7 and 8, the vehicle control module 10 reduces the total braking force of the entire vehicle immediately before stopping the vehicle during regenerative braking so that the vehicle body can move in the longitudinal direction when the vehicle stops. And a front-rear vibration control processing configuration for reducing the vibration in the pitching direction.

  The brake operation mechanism 11 includes a brake pedal 23, an electric booster 24, and a master cylinder 25. The electric booster 24 performs control to increase / decrease the brake hydraulic pressure in accordance with the motor regeneration when the regeneration cooperative control for achieving the driver requested deceleration by the sum of the brake hydraulic pressure and the motor regeneration is performed. The master cylinder 25 creates brake hydraulic pressure to the hydraulic actuator 12.

  The hydraulic actuator 12 includes an electric oil pump, a pressure increasing solenoid valve, a pressure reducing solenoid valve, and the like. Based on a control command from the brake controller 17, the hydraulic actuator 12 uses the master cylinder pressure and the pump pressure as a hydraulic pressure source, and controls the wheel cylinder hydraulic pressure to the left and right front wheel cylinders 13 and 14 and the left and right rear wheel wheel cylinders 15 and 16. produce.

  The brake controller 17 calculates a driver-requested braking force based on pedal stroke information from the brake pedal stroke sensor 26 during brake operation, and performs regenerative cooperative control. From the vehicle control module 10 to the brake controller 17, resolver rotation speed information, vehicle speed information, execution torque information in a hydraulic brake, and the like are input. From the brake controller 17 to the vehicle control module 10, driver request braking force information and torque request information by regenerative cooperative control are output.

[Block configuration of the longitudinal vibration control system when the vehicle is stopped]
FIG. 2 shows a control system configuration of the longitudinal vibration control apparatus A. Hereinafter, the block configuration of the vehicle longitudinal vibration control system will be described with reference to FIG. The “smooth stop” refers to a vehicle stop in which the vibration in the vehicle longitudinal direction and the pitching direction are reduced to suppress the vehicle longitudinal vibration with respect to the vibration on the vehicle spring, that is, the vibration of the vehicle body. The “smooth stop control” described below refers to a control corresponding to the stop-and-run longitudinal vibration control of the present invention.

  As shown in FIG. 2, the vehicle control module 10 of the vehicle front-rear vibration control system includes an accelerator torque calculation unit 10 a, a gradient estimation unit 10 b, a smooth stop target value calculation unit 10 c, and a smooth stop control waveform calculation unit. 10d and a smooth stop start time (vehicle speed) calculation unit 10e. Then, the smooth stop permission / cancellation determination unit 10f, the vehicle stop / hold hydraulic calculation unit 10g, the hydraulic pressure return waveform calculation unit 10h, the nominal vehicle speed calculation unit 10i, the F / B torque calculation unit 10j, and the command torque calculation unit 10k. And.

  As shown in FIG. 2, the brake controller 17 in the vehicle front-rear vibration control system includes a driver-requested braking force calculation unit 17 a, a hydraulic pressure / torque command value calculation unit 17 b, and each wheel hydraulic pressure unit 17 c. ing.

  The accelerator torque calculation unit 10a calculates a torque request according to the accelerator opening APO and the vehicle speed VSP based on the accelerator opening APO from the accelerator opening sensor 18 and the vehicle speed VSP from the vehicle speed sensor 19.

  The gradient estimation unit 10b is based on the estimated rotation value based on the motor rotation speed from the resolver 20, the master cylinder pressure Pm from the master cylinder pressure sensor 21, and the execution torque (regenerative torque) from the command torque calculation unit 10k. Estimate (including disturbance).

  The smooth stop target value calculation unit 10c (final target value setting means) determines the final motor braking / driving force in the process of reducing the total braking force based on the gradient estimated value from the gradient estimating unit 10b and the master cylinder pressure Pm. A target value (hereinafter simply referred to as “target value”) is calculated. This target value is based on the difference between the actual deceleration of the vehicle and the deceleration due to the regenerative braking force during regenerative braking at the timing when the vehicle shifts from the deceleration state to zero vehicle speed. The sum is set to a value that is not more than a predetermined value. In the first embodiment, the target value at the time when the vehicle speed becomes zero is set so that the total sum of the forces acting in the longitudinal direction of the vehicle becomes zero.

The smooth stop control waveform calculation unit 10d (motor control means) is based on the target value from the smooth stop target value calculation unit 10c and the execution torque (regenerative braking force during regenerative braking) from the command torque calculation unit 10k. The torque waveform that is the smooth stop control waveform is calculated. This torque waveform is a waveform that reduces the regenerative braking force with a predetermined decreasing gradient that suppresses the resonance of the vehicle. When the vehicle speed reaches the vehicle speed at which torque reduction starts during regenerative braking, the total braking force is decreased with the decreasing gradient. . The predetermined decreasing gradient is obtained using one of the following two methods.
(a) Apply a filter (LPF) to the step function based on one of the requirements to prevent vehicle resonance and the requirement to reduce the absolute value of torque when the motor torque ripple frequency overlaps the vehicle resonance frequency. It is obtained in advance from a torque waveform that changes over time.
(b) Based on one of the requirements to prevent vehicle resonance and the requirement to reduce the absolute torque value at the timing when the motor torque ripple frequency overlaps the vehicle resonance frequency, a predetermined decrease gradient is applied to a constant gradient (ramp ) And decrease.

  The smooth stop start timing calculation unit 10e (torque reduction start vehicle speed setting means) sets the total braking force immediately before stopping the vehicle in order to set the vehicle longitudinal acceleration when shifting from the vehicle deceleration state to the vehicle speed to zero or less. Set the torque reduction start vehicle speed that starts the reduction. The smooth stop start timing calculation unit 10e determines the torque reduction start vehicle speed based on the execution torque (regenerative braking force during regenerative braking) from the command torque calculation unit 10k and the target value (motor braking / driving) from the smooth stop target value calculation unit 10c. Force final target value) and a predetermined decreasing gradient from the smooth stop control waveform calculation unit 10d. In the smooth stop control of the first embodiment, the torque reduction start vehicle speed is set using a torque reduction start vehicle speed map (FIG. 7) using the low-pass filter parameter, the vehicle deceleration, and the slope. The method of determining the torque reduction start vehicle speed is calculated backward from the estimated time when the wheel speed becomes zero, and the time integral value of deceleration by the torque waveform that suppresses vehicle longitudinal vibration is almost the same as the time integral value of normal stop deceleration. Is set to the vehicle speed at the time of becoming (FIGS. 4 to 6).

The smooth stop permission / cancellation determination unit 10f (motor control cancellation means) permits execution of smooth stop control based on the driver requested braking force, the torque reduction start vehicle speed, and the resolver rotational speed (= motor rotational speed). Judge whether to do or prohibit. When the execution permission determination of smooth stop control is made, an execution determination is output to the command torque calculation unit 10k. When execution prohibition determination of smooth stop control is made, the command torque calculation unit 10k is determined to be prohibited before smooth stop control. Outputs a cancellation decision after smooth stop control. The smooth stop permission / cancel determination unit 10f cancels the smooth stop control (motor control) in the following cases.
(a) The driver's requested deceleration is greater than or equal to the specified value before the start of smooth stop control (motor control) that reduces the regenerative braking force. In this case, normal control for causing the total braking force to follow the driver request deceleration is performed.
(b) When the driver requested deceleration is greater than or equal to the specified value after the smooth stop control is started. In this case, after canceling the smooth stop control, the control is switched to the normal control in which the total braking force follows the driver request deceleration.
(c) When the slip ratio of the wheel is high after the start of smooth stop control that reduces the regenerative braking force. In this case, after the smooth stop control is canceled, the control is switched to the hydraulic brake control for suppressing the wheel slip.

  The vehicle stop holding hydraulic pressure calculation unit 10g calculates a vehicle stop holding hydraulic pressure that is a brake hydraulic pressure necessary to hold the vehicle stop state after the vehicle stops based on the estimated gradient value from the gradient estimation unit 10b.

  The hydraulic pressure return waveform calculation unit 10h is based on the vehicle stop hold hydraulic pressure from the vehicle stop hold hydraulic pressure calculation unit 10g, and after the vehicle is stopped by the smooth stop control performed by the regenerative braking force reduction control, the transition period returns to the brake hydraulic pressure control. Calculate the oil pressure return waveform.

  The nominal vehicle speed calculation unit 10i (nominal vehicle speed calculation means) generates a regenerative torque based on the gradient estimation value from the gradient estimation unit 10b and the torque waveform (= regenerative torque command value) from the smooth stop control waveform calculation unit 10d. The ideal wheel speed (= nominal vehicle speed) corresponding to the command value is calculated. This nominal vehicle speed is set as an ideal vehicle speed characteristic in which the vehicle speed is 0 below a predetermined vehicle speed immediately before stopping.

  The F / B torque calculation unit 10j (F / B torque calculation means) adjusts the nominal vehicle speed based on the nominal vehicle speed from the nominal vehicle speed calculation unit 10i, the actual vehicle speed from the vehicle speed sensor 19, and the torque reduction start vehicle speed. Calculates the F / B torque after reaching the torque reduction start vehicle speed by feedback control to follow the actual vehicle speed.

  The command torque calculation unit 10k calculates a command torque based on a torque request from the accelerator torque calculation unit 10a during running (during non-braking operation), and outputs this as an execution torque to the left and right motor controllers 7 and 8. . At the time of brake operation and before the vehicle speed reaches the torque reduction start vehicle speed, the command torque is calculated based on the torque request from the hydraulic pressure / torque command value calculation unit 17b, and this is used as the execution torque. And output to the hydraulic pressure / torque command value calculation unit 17b. When the braking operation is performed and the vehicle speed reaches the torque reduction start vehicle speed and the smooth stop control execution permission determination is made, the F / B torque from the F / B torque calculation unit 10j and the regeneration from the smooth stop control waveform calculation unit 10d are performed. A command torque is calculated based on the torque command value. The command torque is output as an execution torque to the left and right motor controllers 7 and 8, the gradient estimation unit 10b, and the hydraulic pressure / torque command value calculation unit 17b. When the vehicle speed is zero and the vehicle stops, the command torque is calculated based on the hydraulic pressure waveform from the hydraulic pressure return waveform calculation unit 10h, and the left and right motor controllers 7 and 8 and the hydraulic / torque command are used as the execution torque. It outputs to the value calculating part 17b. Note that feedback information based on the rotational speed / command torque / temperature limitation is input from the left and right motor controllers 7 and 8 to the command torque calculation unit 10k.

  The driver required braking force calculation unit 17a calculates a driver required braking force that appears in the brake operation amount of the driver based on the brake pedal stroke information from the brake pedal stroke sensor 26.

  The hydraulic pressure / torque command value calculation unit 17b determines the driver required braking force based on the driver required braking force from the driver required braking force calculation unit 17a, the vehicle speed, and the resolver rotational speed (= motor rotational speed). A hydraulic pressure command value and a torque command value by regenerative cooperation obtained by the sum of the braking force and the regenerative braking force are calculated. The torque command value for obtaining the regenerative braking force is output to the command torque calculation unit 10k as a torque request, and the execution torque information is input from the command torque calculation unit 10k.

  Each wheel hydraulic pressure unit 17c calculates and calculates the wheel cylinder hydraulic pressure of each wheel 1, 2, 3, 4 based on the hydraulic pressure command value for obtaining the hydraulic braking force from the hydraulic pressure / torque command value calculation unit 17b. A command for obtaining the wheel cylinder hydraulic pressure is output to the hydraulic actuator 12.

[Configuration of front and rear vibration control when stopped]
FIG. 3 shows the flow of the stop vibration control process executed by the vehicle control module 10 and the brake controller 17. Hereinafter, each step of FIG. 3 representing the configuration of the vehicle longitudinal vibration control process will be described. Note that the flowchart of FIG. 3 starts when the driver depresses the brake pedal.

  In step S1, the driver request braking force calculation unit 17a estimates the driver request braking force G1 based on the brake pedal stroke information, and the process proceeds to step S2.

  In step S2, following the estimation of the driver required braking force G1 in step S1, the hydraulic brake + gradient (G4) is estimated from the deceleration (G2) by the motor torque and the current vehicle deceleration G3 (tire angular acceleration), Proceed to step S3.

In step S3, following the estimation of hydraulic brake + gradient (G4) in step S2, it is determined whether or not the actual vehicle speed has reached the determination vehicle speed V1. If YES (actual vehicle speed = V1), the process proceeds to step S4. If NO (actual vehicle speed> V1), the process returns to step S1.
Here, the determination vehicle speed V1 is set to the vehicle speed immediately before the torque reduction start vehicle speed V2.

  In step S4, following the determination that the actual vehicle speed is V1 in step S3, the deceleration (G2) by the motor torque and the hydraulic brake + gradient (G4) are fixed at the determination vehicle speed V1, and the process proceeds to step S5.

  In step S5, following the fixing of the hydraulic brake + gradient (G4) in step S4, it is determined whether or not the driver required deceleration G1 at the determined vehicle speed V1 is equal to or less than the sudden braking determination threshold value. If YES (G1 ≦ rapid braking determination threshold), the process proceeds to step S6. If NO (G1> rapid braking determination threshold), the process proceeds to step S13.

  In step S6, following the determination in step S5 that G1 ≦ the sudden braking determination threshold value, the braking force final value G5 (= G2) is obtained by the hydraulic brake + gradient (G4 = G3-G2) fixed in step S4. -G3 = -G4) is determined, and the process proceeds to step S7.

  In step S7, following the determination of the braking force final value G5 in step S6, the torque reduction start vehicle speed V2 of the smooth stop control is determined by the deceleration G2, the hydraulic brake + gradient (G4), and the braking force final value G5. Proceed to S8.

  In step S8, following the determination of the torque decrease start vehicle speed V2 in step S7, it is determined whether or not the actual vehicle speed has reached the torque decrease start vehicle speed V2. If YES (actual vehicle speed = V2), the process proceeds to step S9. If NO (actual vehicle speed> V2), the determination in step S8 is repeated.

In step S9, following the determination that the actual vehicle speed is V2 in step S8 or the determination that the vehicle is not stopped in step S12, smooth stop control is performed by torque control of the in-wheel motor, and the process proceeds to step S10. move on.
Here, in the smooth stop control, as a countermeasure when a large disturbance enters, torque control that determines the motor torque of the in-wheel motor by F / B control that converges the wheel speed to 0 when the torque reduction start vehicle speed V2 is reached. Do.

In step S10, following execution of the smooth stop control in step S9, it is determined whether or not the brake pedal operation amount is equal to or less than a threshold value. If YES (brake pedal operation amount ≦ threshold), the process proceeds to step S11. If NO (brake pedal operation amount> threshold), the process proceeds to step S13.
In step S10, instead of the brake pedal operation amount, it may be determined whether the driver requested deceleration is equal to or less than a threshold value.

In step S11, following the determination that the brake pedal operation amount ≦ the threshold value in step S10, it is determined whether or not the ABS flag indicating whether or not the ABS that suppresses the braking slip is ABS flag = 0. If YES (ABS flag = 0), the process proceeds to step S12. If NO (ABS flag = 1), the process proceeds to step S13.
Here, the ABS flag = 0 indicates that the ABS is not operating, and the ABS flag = 1 indicates that the ABS is operating. Note that wheel slip may be directly detected instead of the ABS flag.

  In step S12, following the determination that the ABS flag = 0 in step S11, it is determined whether or not the vehicle is stopped. If YES (stop the vehicle), the process proceeds to step S13. If NO (decelerates before the vehicle stops), the process returns to step S9.

  In step S13, it is determined that the vehicle is stopped in step S12, G1 in step S5 is determined to be a sudden braking determination threshold, or the brake pedal operation amount in step S10 is greater than the threshold. Following the determination or the determination that the ABS flag = 1 in step S11, the control for obtaining the braking force is switched to the hydraulic brake, and the process proceeds to the end.

Next, the operation will be described.
The functions of the longitudinal vibration control device A of the first embodiment are as follows: [How to determine the torque reduction start vehicle speed], [Smooth stop control action], [Long stop vibration control action when stopped], [Deceleration control action immediately before stop], [When stopped] Other characteristic actions of the longitudinal vibration control] will be described separately.

[How to determine the starting speed of torque reduction]
In step S7, the torque reduction start vehicle speed V2 of the smooth stop control is determined. The torque reduction start vehicle speed V2 is uniquely determined when the vehicle deceleration and the LPF parameters (frequency / order) are determined. That is, once the decreasing gradient and the final target value are determined, the torque decrease start vehicle speed V2 can be obtained if the regenerative braking force (executed regenerative braking force) can be detected. Hereinafter, a method for determining the torque reduction start vehicle speed V2 will be described with reference to FIGS.

  First, if the vehicle deceleration remains constant, as shown in FIG. 4 (a), the vehicle stops at time t1, and the vehicle deceleration characteristic changes from the reference point a1 at time t1 to vehicle deceleration 0. The step characteristics are changed. As shown in FIG. 4 (b), a smooth waveform characteristic B obtained by applying LPF (low-pass filter) to the step characteristic is drawn on this step characteristic, and the stop point at which the vehicle speed becomes 0 is defined as a2. When this waveform characteristic B is moved in the direction of returning the time as shown by the arrow in FIG. 4C and crosses the vehicle deceleration characteristic shown in FIG. 4A, the waveform characteristic B is shown in FIG. 4C. In this way, the waveform characteristic B is adjusted in the time axis direction so that the two areas of the area C and the area D are the same. Then, as shown in FIG. 4 (d), an intersection E of the vehicle deceleration characteristic (FIG. 4 (a)) and the adjusted waveform characteristic B (FIG. 4 (c)) is determined, and the intersection E is determined by the vehicle deceleration. The reaching vehicle speed E ′ is calculated backward, and this vehicle speed E ′ is set as the torque reduction start vehicle speed V2 of the smooth stop control.

  The method of determining the torque reduction start vehicle speed V2 is the same when there is a road surface gradient or brake hydraulic pressure. That is, when the vehicle is going uphill (gradient is +), the torque reduction start vehicle speed V2 of the smooth stop control is determined as shown in FIG. 5, and when the vehicle is going downhill (gradient is-), as shown in FIG. Then, the torque reduction start vehicle speed V2 of the smooth stop control is determined. If the total braking force is reduced during an uphill slope, the driver-requested braking force until time t0 when the torque reduction start vehicle speed is reached decreases from time t0, and from time t2 when the braking force becomes zero, the gradient equivalent driving force Turns to (power running) and the vehicle stops. On the other hand, if the total braking force is reduced when the vehicle is on a downhill slope, the driver-required braking force until time t0 when the vehicle speed reaches the torque reduction start speed is only gradually decreased from time t0, and the gradient equivalent braking force (regeneration) is maintained. The vehicle stops while standing.

  In this way, the LPF frequency is the H frequency that prevents vehicle resonance, and the optimum torque reduction start vehicle speed that can converge the total braking force to zero when the vehicle is stopped even when the vehicle deceleration, gradient, and brake hydraulic pressure are different. Collect data by experiment. The torque reduction start vehicle speed map of FIG. 7 is a map of the torque reduction start vehicle speed based on this experimental data. This torque reduction start vehicle speed map is in the form of a torque reduction start vehicle speed table with vertical and horizontal axes of deceleration [G] (vehicle deceleration) and slope (actual slope + hydraulic pressure) [%] (gradient and brake hydraulic pressure). For example, when the deceleration [G] is 0.25 and the inclination is −5%, the torque reduction start vehicle speed = X52 is determined.

  In the above description, an example in which the torque reduction start vehicle speed V2 is obtained from a torque waveform that changes smoothly with time by applying a filter (LPF) to the step function has been described. The torque waveform can also be obtained. In this case, as shown in FIG. 4 (b), by drawing a linear waveform characteristic I (dashed line characteristic) having a constant ramp slope in the step characteristic, the torque reduction starting vehicle speed is obtained in the same manner as in the case of using the filter (LPF). V2 can be obtained.

[Smooth stop control action]
In step S9, as a measure against a large disturbance, smooth stop control is executed when the torque reduction start vehicle speed V2 is reached. In this smooth stop control, when the torque reduction start vehicle speed V2 is reached, torque control is performed to determine the motor torque of the in-wheel motor by F / B control that converges the wheel speed to zero.

  That is, as shown in FIG. 8, when the torque reduction start vehicle speed V2 is reached at time t1, an ideal wheel speed corresponding to the torque command value is obtained every moment from time t1, and the calculated ideal wheel speed is obtained. F / B control is performed to follow the wheel speed from moment to moment (wheel speed servo). For example, when there is no F / B control, the vehicle speed may not become zero due to the influence of disturbance as shown in the vehicle speed characteristic (without F / B) in FIG. On the other hand, by performing wheel speed servo control, as shown in the motor torque characteristic (with F / B) in FIG. 8, torque that corrects the wheel speed difference is output, and the vehicle speed characteristic (F Stop at zero vehicle speed as shown in / B).

The wheel speed servo control is started in the first embodiment when the torque reduction start vehicle speed V2 is reached. However, the F / B control should be started at a certain vehicle speed during torque reduction (vehicle speed before the torque decrease start vehicle speed V2 before stopping) or when the motor torque reaches the target value during torque reduction. May be.
For example, as shown in FIG. 9, when the vehicle speed immediately before stopping is reached at time t2, F / B control targeting wheel speed 0 is started from time t2. Thus, for example, when there is no F / B control, the vehicle speed may not become zero due to the influence of disturbance as shown in the vehicle speed characteristic (without F / B) in FIG. On the other hand, as shown in the motor torque characteristic (with F / B) in FIG. 9, by performing F / B control with a target wheel speed of 0, a torque that corrects the wheel speed difference is output, As shown in the vehicle speed characteristics (with F / B) in FIG. 9, the vehicle stops at time t3 at zero vehicle speed.

[Longitudinal vibration control when stopped]
Hereinafter, the front-rear vibration control action at the time of stopping will be described based on the flowchart shown in FIG.
Until the driver depresses the brake pedal and the actual vehicle speed reaches the determination vehicle speed V1, the flow of steps S1 → S2 → step S3 is repeated in the flowchart of FIG. In step S1, the driver requested braking force G1 is estimated based on the brake pedal stroke information. In step S2, the hydraulic brake + gradient (G4) is estimated from the deceleration (G2) by the motor torque and the current vehicle deceleration G3. .

  If it is determined in step S3 that the actual vehicle speed has reached the determination vehicle speed V1, and if it is determined in step S5 that the driver required deceleration G1 is equal to or less than the sudden braking determination threshold, steps S3 to S4 to step S5 are performed. → Proceed to step S6 → step S7. In step S4, the deceleration (G2) by the motor torque and the hydraulic brake + gradient (G4) are fixed at the determination vehicle speed V1. In step S6, the final braking force value G5 is determined by the hydraulic brake + gradient (G4) fixed in step S4. In step S7, the torque reduction start vehicle speed V2 of the smooth stop control is determined by the deceleration G2, the hydraulic brake + gradient (G4), and the braking force final value G5.

  When it is determined in the next step S8 that the actual vehicle speed has reached the torque reduction start vehicle speed V2, the flow from step S8 to step S9 → step S10 → step S11 → step S12 is repeated until the vehicle stop determination is made. That is, during the period from the torque reduction start vehicle speed V2 to the vehicle stop, the smooth stop control by the torque control of the in-wheel motor is executed in step S9. When it is determined in step S12 that the vehicle is stopped, the process proceeds from step S12 to step S13, and in step S13, the control for obtaining the braking force is switched to the hydraulic brake.

  If it is determined in step S5 that G1> the sudden braking determination threshold value when the actual vehicle speed is between the determination vehicle speed V1 and the torque reduction start vehicle speed V2, the process proceeds to step S13, where the smooth stop control is canceled and the braking force is obtained. The control is a hydraulic brake. During execution of the smooth stop control from the torque reduction start vehicle speed V2 to the vehicle stop, when it is determined in step S10 that the brake pedal operation amount> the threshold value, or in step S11, it is determined that the ABS flag = 1. When it is determined, the process proceeds to step S13, the smooth stop control is canceled, and the control for obtaining the braking force is switched to the hydraulic brake.

  Next, based on FIG. 10 to FIG. 12, the front / rear vibration control operation during stopping, which is a smooth stop control operation under different road surface gradients and brake pedal depression forces, will be described.

FIG. 10 shows each characteristic when an in-wheel motor electric vehicle stops on a flat road with a brake pedal depression force of 0.15G.
From time t1 when the vehicle speed becomes V0 (for example, 10 km / h) to time t2 when the vehicle speed becomes V1 (for example, 2 km / h), the regenerative torque of 0.15G corresponds to the brake pedal depression force of 0.15G Vehicle deceleration 0.15G is obtained. That is, the hydraulic brake is 0G, and the gradient / hydraulic pressure estimation is 0%. When the vehicle speed V1 is reached at time t2, the torque reduction start vehicle speed V2 (for example, 1.5 km / h) of the smooth stop control is determined by the deceleration G2, the hydraulic brake + gradient (G4), and the braking force final value G5. The When the torque reduction start vehicle speed V2 is reached at time t3, the regenerative torque of 0.15G is gradually reduced toward the regenerative torque until time t4 when the vehicle speed becomes zero. Decrease from 15G. At time t4 when the vehicle speed is zero, the brake hydraulic pressure is increased so that the brake force corresponding to the brake pedal depression force 0.15G is obtained by the hydraulic brake, and the vehicle stop state is maintained.

FIG. 11 shows each characteristic when an in-wheel motor electric vehicle stops on a flat road with a brake pedal depression force of 0.25G.
From the brake depression operation start time t0 to the time t1 when the vehicle speed becomes V0 (for example, 10 km / h), regenerative cooperative control is performed by the regenerative torque that rises to 0.15G and the hydraulic brake that rises to 0.10G. . By this regenerative cooperative control, the vehicle deceleration increases to 0.25G corresponding to the brake pedal depression force increasing to 0.25G. Between time t1 when the vehicle speed becomes V0 (for example, 10 km / h) and time t2 when the vehicle speed becomes V1 (for example, 2 km / h), braking is performed by a regenerative torque of 0.15 G and a hydraulic brake of 0.10 G. A vehicle deceleration 0.25G corresponding to the pedal depression force 0.25G is obtained. In other words, the hydraulic brake is 0.10 G, and the gradient / hydraulic pressure estimation is 10%. When the vehicle speed V1 is reached at time t2, the torque reduction start vehicle speed V2 (for example, 1.5 km / h) of the smooth stop control is determined by the deceleration G2, the hydraulic brake + gradient (G4), and the braking force final value G5. The When the torque reduction start vehicle speed V2 at time t3, until the time t4 when the vehicle speed becomes zero, the regenerative torque of 0.15G is further increased from zero regenerative torque to hydraulic and gradient equivalent power running (0.1G: hydraulic braking force cancellation) Following this, the vehicle deceleration also decreases from 0.25G. At time t4 when the vehicle speed is zero, the regenerative torque is returned to zero from the hydraulic pressure and gradient equivalent power running (0.1 G), and the brake hydraulic pressure is obtained so that the braking force corresponding to the brake pedal depression force 0.25 G is obtained by the hydraulic brake. Is increased. After time t5, the vehicle stop state is maintained by the hydraulic brake corresponding to the brake pedal depression force 0.25G.

FIG. 12 shows each characteristic when the 5% downhill road is stopped by a brake pedal depression force of 0.25 G in an in-wheel motor electric vehicle.
From the brake depression operation start time t0 to the time t1 when the vehicle speed becomes V0 (for example, 10 km / h), regenerative cooperative control is performed by the regenerative torque that rises to 0.15G and the hydraulic brake that rises to 0.10G. . This regenerative cooperative control increases the vehicle deceleration to 0.20G. That is, the brake pedal depressing force increases to 0.25G, but the vehicle deceleration is obtained by subtracting the downward gradient by -5%, and the gradient / hydraulic estimation at time t1 is from -5% to 0.10G hydraulic brake. It changes to 5% according to. Between time t1 when the vehicle speed becomes V0 (for example, 10 km / h) and time t2 when the vehicle speed becomes V1 (for example, 2 km / h), braking is performed by a regenerative torque of 0.15 G and a hydraulic brake of 0.10 G. A vehicle deceleration of 0.20 G obtained by subtracting -5% of the downward gradient from the pedal depression force of 0.25 G is obtained. That is, the hydraulic brake is 0.10 G, and the gradient / hydraulic pressure estimation is 5%. When the vehicle speed V1 is reached at time t2, the torque reduction start vehicle speed V2 (for example, 1.5 km / h) of the smooth stop control is determined by the deceleration G2, the hydraulic brake + gradient (G4), and the braking force final value G5. The When the torque reduction start vehicle speed V2 at time t3, until the time t4 when the vehicle speed becomes zero, the regenerative torque of 0.15G is further increased from zero regenerative torque to hydraulic and gradient equivalent power running (0.1G: hydraulic braking force cancellation) Following this, the vehicle deceleration also decreases from 0.20G. At time t4 when the vehicle speed is zero, the regenerative torque is returned to zero from the hydraulic pressure and gradient equivalent power running (0.1 G), and the brake hydraulic pressure is obtained so that the braking force corresponding to the brake pedal depression force 0.25 G is obtained by the hydraulic brake. Is increased. After time t5, the vehicle stop state is maintained by the hydraulic brake corresponding to the brake pedal depression force 0.25G.

[Deceleration control before stopping]
In the first embodiment, when the vehicle speed reaches the torque decrease start vehicle speed V2 during the regenerative braking, the regenerative braking force is decreased with a predetermined decreasing gradient that suppresses the resonance of the vehicle, thereby reducing the total braking force with the decreasing gradient. Control is performed. At this time, the final target value at the timing when the vehicle shifts from the deceleration state to the vehicle speed zero is set to a value that makes the total sum of the forces acting in the vehicle front-rear direction smaller than a predetermined value. The torque reduction start vehicle speed V2 is set based on the regenerative braking force during the regenerative braking, the final target value of the motor braking / driving force, and a predetermined decrease gradient.

  Therefore, when the vehicle is stopped, the torque decreasing gradient and the torque decrease starting vehicle speed V2 are determined so that the longitudinal vibration G is equal to or less than a predetermined value, and the total braking force of the entire vehicle is decreased immediately before stopping the vehicle during braking. Take control. For example, if deceleration = 0 at the moment of stopping without changing the deceleration of the entire vehicle, as shown in the upper part of FIG. On the other hand, by smoothly reducing the deceleration of the entire vehicle, as shown in the lower part of FIG. 13, the vehicle vibration at the time of stopping is suppressed smaller than in the upper part of FIG. 13, and the pitching at the time of stopping the vehicle is reduced. Is done. As shown in FIG. 14, the vehicle speed characteristic and the motor torque characteristic depending on the presence or absence of the smooth stop control are the vehicle speed change characteristic and the motor torque between the time t1 when the torque reduction start vehicle speed V2 is reached and the vehicle stop time t2. The change characteristics are different.

The disturbance that hinders the smooth stop control includes the case where the disturbance is zero, and considers hydraulic intervention, gradient change, vehicle weight change, wind, and running resistance change.
That is, the actual deceleration changes even when the regenerative braking force is constant, when the hydraulic brake intervenes, the road surface gradient changes, the occupants increase, or the vehicle state changes. For this reason, first, the final target value of the braking / driving force of the motor in the step of reducing the total braking force is less than or equal to a predetermined value at the sum of the forces acting on the vehicle in the front-rear direction when the vehicle shifts from the deceleration state to the vehicle speed zero. Is set to the value Thus, it is assumed that the vehicle is almost stopped just before the vehicle stops. By determining the vehicle speed at which torque reduction starts based on the regenerative braking force during regenerative braking, the decreasing gradient that suppresses vehicle resonance, and the final target value of the motor braking / driving force, vibration is reliably suppressed immediately before stopping. In addition, the vehicle can be brought into a substantially stopped state at the end of the process of reducing the total braking force. Therefore, regardless of changes in the vehicle state, the vehicle can be stopped by suppressing the vehicle longitudinal vibration just before the vehicle stops, and the vibration suppression control just before the vehicle can be stopped without using the vehicle model.

  As a result, it is possible to suppress the longitudinal vibration just before the vehicle stops without using the vehicle model. Incidentally, FIG. 15 shows each characteristic of the vehicle speed, the motor torque, and the vehicle front-rear G at the time of stopping in the in-wheel motor electric vehicle to which the vibration suppression control device of the first embodiment is applied. As is clear from FIG. 15, by performing control to reduce the motor torque from the regeneration side to zero immediately before the vehicle stops, the vehicle speed converges to zero while drawing a smooth curve. Then, as shown by the arrow H in FIG. 15, the vehicle front-rear G confirms that the fluctuation of the vehicle front-rear G is kept small in the vehicle stop area, and the “cuckling brake” that is a shock at the time of vehicle stop is prevented. can do.

[Other characteristic effects of front and rear vibration control when the vehicle is stopped]
In the first embodiment, the torque reduction start vehicle speed V2 is set by using a torque reduction start vehicle speed map (FIG. 7) using low-pass filter parameters (frequency / order), vehicle deceleration, and inclination.
That is, when the decrease gradient and the final target value are determined, the torque decrease start vehicle speed V2 can be determined if the regenerative braking force (executed regenerative braking force) can be detected thereafter. Specifically, it can be seen from the current regenerative braking force that if the reduction of the regenerative braking is started at a vehicle speed of a predetermined decreasing gradient at a speed of km / h, the final target value can be obtained at a substantially zero vehicle speed. However, when calculating the torque reduction start vehicle speed by sequentially calculating, it takes time for the calculation process. For example, the determination vehicle speed for determining the torque reduction start vehicle speed is determined with a sufficient time margin until the torque reduction start vehicle speed is reached. It is necessary to reduce the control accuracy accordingly.
On the other hand, by setting the torque decrease start vehicle speed V2 using the torque decrease start vehicle speed map (FIG. 7), complicated calculation processing can be omitted, and the determination vehicle speed V1 and the torque decrease start vehicle speed V2 can be set. By bringing them closer, it is possible to improve the control accuracy of the longitudinal vibration control when the vehicle is stopped.

In the first embodiment, a predetermined decrease gradient is obtained in advance by a torque waveform that changes with time by applying a filter (LPF) to a vehicle deceleration step function.
In other words, the predetermined decreasing gradient is determined based on any one of the requirement to prevent the vehicle resonance and the requirement to reduce the torque absolute value at the timing when the torque ripple frequency of the motor overlaps the vehicle resonance frequency.
Accordingly, during the stop longitudinal vibration control, the vehicle longitudinal vibration due to vehicle resonance can be suppressed.

In the first embodiment, the time integral value of the deceleration by the torque waveform that suppresses the vehicle longitudinal vibration is calculated backward from the estimated time when the wheel speed becomes zero, and the time integral value of the normal stop deceleration becomes substantially the same. The vehicle speed at is set as the torque reduction start vehicle speed V2.
In other words, the time integral value of deceleration by the torque waveform that suppresses longitudinal vibration and the time integral value (energy) of normal stop deceleration are made substantially the same, and are determined by calculating backward from wheel speed 0. .
Therefore, when the braking torque reaches the final target value, it is possible to set the torque decrease start vehicle speed V2 that satisfies the requirement that the wheel speed is 0 and can reliably stop the vehicle.

In the first embodiment, the F / B torque calculation unit 10j that calculates the F / B torque by the feedback control of the wheel speed with the target wheel speed of 0 below the predetermined vehicle speed immediately before the stop is used.
Therefore, when a large disturbance (wind) enters, the feedback control of the wheel speed becomes a countermeasure against the disturbance, and the vehicle can be surely stopped regardless of the deceleration change of the vehicle due to the disturbance input.

The first embodiment includes a nominal vehicle speed calculation unit 10i that obtains an ideal wheel speed according to the regenerative torque command value, and the F / B torque calculation unit 10j sets the ideal wheel speed from the nominal vehicle speed calculation unit 10i. The F / B torque after reaching the torque reduction start vehicle speed V2 is calculated by feedback control of the wheel speed to follow the actual wheel speed.
Therefore, the vehicle can be stopped due to a smooth decrease in the vehicle speed due to a decrease in the actual wheel speed following the ideal wheel speed, regardless of the deceleration change of the vehicle due to disturbance input.

In the first embodiment, when the driver requested deceleration is greater than or equal to a predetermined value before the start of the motor control for reducing the regenerative braking force, or when the driver requested deceleration is greater than or equal to the predetermined value after the start of the motor control, the motor control is canceled, A smooth stop permission / cancel determination unit 10f that causes the total braking force to follow the driver requested deceleration is employed.
In other words, if a deep brake pedal operation is performed by the driver or a brake pedal depressing operation is performed, the driver requested deceleration is greater than a predetermined value before the start of motor control, or the driver requested deceleration after the start of motor control. Exceeds a predetermined value. That is, when such a brake pedal operation by the driver occurs, it can be determined that the driver's intention is a time when a sudden deceleration or a sudden stop is requested.
Therefore, when the driver request deceleration exceeds a predetermined value, the driver's intention to request rapid deceleration or sudden stop is given priority over the smooth stop request, and the braking force is made to follow the driver request deceleration equivalent in response to the driver intention. be able to.

In the first embodiment, when the wheel slip rate is high after the start of the motor control for reducing the regenerative braking force, the smooth stop permission / cancellation determination unit 10f cancels the motor control and switches to the hydraulic brake control that suppresses the wheel slip. It was set as the structure switched.
Here, the judgment of the wheel slip rate includes ABS operation or estimation by control logic, but if the wheel slip rate is high, the motor torque control is stopped and switched to a hydraulic brake that suppresses wheel slip. It is done.
Therefore, when a wheel slip occurs during front-rear vibration control when the vehicle is stopped, the vehicle behavior can be stabilized and the vehicle can stop.

Next, the effect will be described.
In the longitudinal vibration control apparatus A of the first embodiment, the effects listed below can be obtained.

(1) Having a motor that generates regenerative braking force in the drive source (left and right left inverters & motors 5, 6), and stopping the vehicle by reducing the total braking force of the entire vehicle immediately before stopping the vehicle during regenerative braking In the longitudinal vibration control device A for reducing vibrations in at least one of the longitudinal direction and the pitching direction of the vehicle body at the time of
Torque reduction start vehicle speed setting means (smooth stop start timing calculation unit 10e) for setting a torque decrease start vehicle speed V2 for starting a decrease in the total braking force immediately before the vehicle stops;
The final target value of the motor braking / driving force in the process of reducing the total braking force is set to a value at which the sum of the forces acting in the vehicle longitudinal direction is set to a predetermined value or less at the timing when the vehicle shifts from the deceleration state to the vehicle speed zero. Target value setting means (smooth stop target value calculator 10c);
When the vehicle speed reaches the torque reduction start vehicle speed V2 during the regenerative braking, the regenerative braking force is reduced at a predetermined decreasing gradient that suppresses the resonance of the vehicle, so that the motor control means (smooth) reduces the total braking force at the decreasing gradient. Stop control waveform calculation unit 10d),
The torque decrease start vehicle speed setting means (smooth stop start timing calculation unit 10e) is performing regenerative braking at a torque decrease start vehicle speed V2 that causes the vehicle longitudinal acceleration when the vehicle shifts from the decelerating state to the vehicle speed zero or less. Is set based on the regenerative braking force, the final target value of the motor braking / driving force, and a predetermined decreasing gradient (FIG. 2).
For this reason, the longitudinal vibration just before a vehicle stop can be suppressed, without using a vehicle model.

(2) The torque decrease start vehicle speed setting means (smooth stop start timing calculation unit 10e) sets the torque decrease start vehicle speed V2 using a torque decrease start vehicle speed map using low-pass filter parameters, vehicle deceleration, and slope. (FIG. 7).
For this reason, in addition to the effect of (1), complicated calculation processing can be omitted, and the control accuracy of the stoppage longitudinal vibration control can be improved by bringing the judgment vehicle speed close to the torque reduction start vehicle speed.

(3) The motor control means (smooth stop control waveform calculation unit 10d) is either one of the requirement to prevent the vehicle resonance and the requirement to reduce the absolute torque value at the timing when the motor torque ripple frequency overlaps the vehicle resonance frequency. Based on the requirements, a predetermined decreasing gradient is obtained in advance by a torque waveform that changes with time by applying a filter (LPF) to the vehicle deceleration step function (FIG. 4).
For this reason, in addition to the effect of (1) or (2), the longitudinal vibration of the vehicle due to vehicle resonance can be suppressed during the longitudinal vibration control when the vehicle is stopped.

(4) Torque reduction start vehicle speed setting means (smooth stop start timing calculation unit 10e) calculates a time integral value of deceleration by a torque waveform that reversely calculates from a time estimated to become wheel speed 0 and suppresses vehicle longitudinal vibration, The vehicle speed at the time when the normal stop deceleration time integral value is substantially the same is set as the torque reduction start vehicle speed (FIG. 4).
For this reason, in addition to the effects (1) to (3), when the braking torque reaches the final target value, the vehicle speed V2 that satisfies the requirement that the wheel speed is 0 and can reliably stop the vehicle is set. Can do.

(5) It has F / B torque calculation means (F / B torque calculation unit 10j) that calculates F / B torque by feedback control of the wheel speed at a target wheel speed of 0 or less immediately below the predetermined vehicle speed immediately before the stop (FIG. 9). ).
For this reason, in addition to the effects of (1) to (4), when a disturbance occurs, feedback control of the wheel speed becomes a countermeasure against disturbance, and the vehicle is surely stopped regardless of changes in the deceleration of the vehicle due to disturbance input. Can do.

(6) Nominal vehicle speed calculation means (nominal vehicle speed calculation unit 10i) for obtaining an ideal wheel speed according to the regenerative torque command value;
The F / B torque calculation means (F / B torque calculation section 10j) is a wheel speed feedback control that causes the actual wheel speed to follow the ideal wheel speed from the nominal vehicle speed calculation means (nominal vehicle speed calculation section 10i). Thus, the F / B torque after reaching the torque reduction start vehicle speed V2 is calculated (FIG. 8).
For this reason, in addition to the effect of (5), the vehicle can be stopped due to a smooth decrease in the vehicle speed due to the decrease in the actual wheel speed following the ideal wheel speed, regardless of the change in the vehicle deceleration due to the disturbance input.

(7) If the driver required deceleration is greater than or equal to the specified value before the start of motor control to reduce the regenerative braking force, or if the driver requested deceleration is greater than or equal to the specified value after the start of motor control, the motor control is canceled and the total control Motor control canceling means (smooth stop permission / cancellation determination unit 10f) for following the power corresponding to the driver requested deceleration is provided (S5 in FIG. 3 or NO in S10).
For this reason, in addition to the effects of (1) to (6), if the driver's requested deceleration exceeds a predetermined value, the driver's intention requesting rapid deceleration or sudden stop is given priority over the smooth stop request, and the driver's intention is responded. Thus, the braking force can be made to follow the driver requested deceleration.

(8) The motor control canceling means (smooth stop permission / cancellation determination unit 10f) cancels the motor control and suppresses the wheel slip when the wheel slip rate is high after the start of the motor control for reducing the regenerative braking force. Switch to brake control (NO in S11 of FIG. 3).
For this reason, in addition to the effect of (7), when a wheel slip occurs during the stop longitudinal vibration control, the vehicle behavior can be stabilized and stopped.

  The vehicle longitudinal vibration control apparatus according to the present invention has been described based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and the claims relate to each claim. Design changes and additions are allowed without departing from the scope of the invention.

  In the first embodiment, as the final target value setting means, the example of the smooth stop target value calculation unit 10c that sets the final target value at the time point t4 when the vehicle speed becomes 0 so that the sum of the braking forces becomes zero is shown. However, as the final target value setting means, even if the total braking force is not zero, some braking / driving force may be generated as long as it is within a predetermined value permitted as the longitudinal vibration.

  In the first embodiment, as an example of the final target value setting means, the braking force final value G5 (final target value) is obtained by G2-G3 from the deceleration G2 by the motor torque and the current vehicle deceleration G3. However, the final target value setting means may be a means for estimating the final target value using an inclinometer, MC pressure sensor, or hydraulic pressure sensor. In short, what is necessary is just to estimate the disturbance and determine the final target value.

  In the first embodiment, as shown in FIG. 7, a torque reduction start vehicle speed map is prepared in advance as a torque reduction start vehicle speed setting means, and the torque reduction start vehicle speed V2 is set using the map in the front-rear vibration control during stoppage. The example of the smooth stop start time (vehicle speed) calculation part 10e was shown. However, as the torque reduction start vehicle speed setting means, the torque reduction start vehicle speed may be obtained by sequentially calculating according to the method of determining the torque reduction start vehicle speed V2 shown in FIGS.

  In the first embodiment, an example in which the vehicle longitudinal vibration control device of the present invention is applied to an in-wheel motor electric vehicle (IWM-EV) is shown. However, the longitudinal vibration control apparatus of the present invention can also be applied to a one-motor electric vehicle that drives the front wheels with one motor, or a hybrid vehicle that has an internal combustion engine and a motor as drive sources. In short, the present invention can be applied to any vehicle that can control the total braking force of the vehicle with the regenerative braking force. However, in-wheel motor electric vehicles do not have long drive shafts or differential gears, unlike the one-motor electric vehicles, and the output torque of the motor is transmitted almost directly to the wheels. Is good.

A In-wheel motor vehicle longitudinal vibration control device 1 Left front wheel 2 Right front wheel 3 Left rear wheel 4 Right rear wheel 5 Left inverter & motor 6 Right inverter & motor 7 Left motor controller 8 Right motor controller 9 Battery 10 Vehicle control module 10a Accelerator Torque calculator 10b Gradient estimator 10c Smooth stop target value calculator (final target value setting means)
10d Smooth stop control waveform calculation unit (motor control means)
10e Smooth stop start time calculation section (torque reduction start vehicle speed setting means)
10f Smooth stop permission / cancellation determination unit (motor control canceling means)
10g Vehicle stop holding hydraulic pressure calculation unit 10h Hydraulic pressure return waveform calculation unit 10i Nominal vehicle speed calculation unit (nominal vehicle speed calculation means)
10j F / B torque calculation part (F / B torque calculation means)
10k command torque calculation unit 11 brake operation mechanism 12 hydraulic actuator 13 left front wheel wheel cylinder 14 right front wheel wheel cylinder 15 left rear wheel wheel cylinder 16 right rear wheel wheel cylinder 17 brake controller 17a driver required braking force calculation unit 17b hydraulic / torque command value Calculation part 17c Each wheel hydraulic pressure part

Claims (8)

Having a motor that generates regenerative braking force in the drive source, and reducing the total braking force of the entire vehicle immediately before stopping the vehicle during regenerative braking, so that at least one of the longitudinal and pitching directions of the vehicle body when the vehicle stops In a vehicle longitudinal vibration control device that reduces vibration in one direction,
Torque decrease start vehicle speed setting means for setting a torque decrease start vehicle speed for starting a decrease in the total braking force immediately before the vehicle stops;
The final target value of the motor braking / driving force in the reduction process of the total braking force is set to a value that makes the sum of the forces acting in the vehicle longitudinal direction not more than a predetermined value at the timing when the vehicle shifts from the deceleration state to the vehicle speed zero. A final target value setting means;
When the vehicle speed reaches the torque reduction start vehicle speed during the regenerative braking, motor control means for reducing the total braking force with the decreasing gradient by decreasing the regenerative braking force with a predetermined decreasing gradient that suppresses the resonance of the vehicle. And having
The torque decrease start vehicle speed setting means sets the torque decrease start vehicle speed at which the vehicle longitudinal acceleration when the vehicle shifts from a deceleration state to a vehicle speed of zero or less is a predetermined allowable value, the regenerative braking force during the regenerative braking, A longitudinal vibration control device for a vehicle, which is set based on a final target value of a motor braking / driving force and the predetermined decrease gradient. In the vehicle longitudinal vibration control device according to claim 1,
The torque decrease start vehicle speed setting means sets the torque decrease start vehicle speed using a torque decrease start vehicle speed map using a low-pass filter parameter, vehicle deceleration, and inclination. . In the vehicle longitudinal vibration control device according to claim 1 or 2,
The motor control means, based on any one of the requirement to prevent the resonance of the vehicle and the requirement to reduce the absolute torque value of the timing at which the torque ripple frequency of the motor overlaps the vehicle resonance frequency, the predetermined decreasing gradient, A vehicle longitudinal vibration control device characterized in that the vehicle deceleration step function is obtained in advance by applying a filter to a time-varying torque waveform. In the vehicle longitudinal vibration control device according to any one of claims 1 to 3,
The torque reduction start vehicle speed setting means calculates backward from the estimated time when the wheel speed becomes zero, and the time integral value of deceleration based on the torque waveform that suppresses vehicle longitudinal vibration and the time integral value of normal stop deceleration are almost equal. A vehicle longitudinal vibration control device characterized in that the vehicle speed at the same time is set as the torque reduction start vehicle speed. In the vehicle longitudinal vibration control device according to any one of claims 1 to 4,
A vehicle longitudinal vibration control device comprising F / B torque calculation means for calculating F / B torque by feedback control of a wheel speed targeted at a wheel speed of 0 below a predetermined vehicle speed immediately before stopping. In the vehicle longitudinal vibration control device according to claim 5,
Nominal vehicle speed calculation means for obtaining an ideal wheel speed according to the regenerative torque command value,
The F / B torque calculation means is an F / B after reaching the torque reduction start vehicle speed by feedback control of the wheel speed that causes the actual wheel speed to follow the ideal wheel speed from the nominal vehicle speed calculation section every moment. A vehicle longitudinal vibration control device that calculates B torque. In the vehicle longitudinal vibration control device according to any one of claims 1 to 6,
If the driver requested deceleration is greater than or equal to a predetermined value before the start of motor control to reduce the regenerative braking force, or if the driver requested deceleration is greater than or equal to a predetermined value after the start of motor control, the motor control is canceled and the total control A vehicle longitudinal vibration control apparatus characterized by comprising motor control canceling means for causing power to follow the driver's required deceleration. In the vehicle longitudinal vibration control device according to claim 7,
The motor control canceling means cancels the motor control and switches to hydraulic brake control that suppresses wheel slip when the wheel slip rate is high after the start of motor control for reducing the regenerative braking force. A vehicle longitudinal vibration control device.