JP2006142963A - Driving force control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that in control downshifting a change gear ratio according to the distance from a preceding vehicle deceleration is excessively increased in an accelerator-off state to uselessly increase the following distance or deteriorate the follow-on acceleration response. <P>SOLUTION: This device comprises a following distance sensor for detecting the accelerating state of the preceding vehicle, the distance therefrom, or the like. In this device, when it is detected that the own vehicle is decelerating and the preceding vehicle is accelerating, not only the target gear change ratio of a transmission is corrected to the downshifting side, but also the target output of an engine is corrected to the increasing side over idle. According to this, the deceleration in the accelerator-off state is suppressed to avoid sudden extension of the following distance and improve the acceleration response from this state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement in a driving force control device for appropriately maintaining an inter-vehicle distance between other vehicles preceding the vehicle while traveling.

As a device for keeping the inter-vehicle distance constant, a device as disclosed in Patent Document 1 is known. This is because if the inter-vehicle distance from the preceding vehicle is long, the automatic transmission gear ratio is downshifted to ensure sufficient acceleration, while if the inter-vehicle distance is short, the gear ratio is upshifted and more than necessary. I try not to accelerate.
Japanese Patent Laid-Open No. 2002-13623

  In such a control, when the inter-vehicle distance is large, the gear ratio is downshifted according to the inter-vehicle distance. Therefore, when the preceding vehicle starts accelerating while the vehicle is decelerating with the accelerator off, the inter-vehicle distance Becomes longer, and the gear ratio is downshifted according to the inter-vehicle distance. At this time, since the throttle opening is fully closed, the negative driving torque increases with the downshift, and the deceleration increases. As a result, there is a problem in that the distance between the preceding vehicle and the preceding vehicle spreads more than expected, giving the driver a unique feeling of strangeness, the so-called “feeling left behind”. Further, since the throttle is fully closed, the acceleration is delayed due to the response delay of the engine when the accelerator is subsequently depressed to start the acceleration.

  In the present invention, the target drive torque setting means for setting the target drive torque of the vehicle based on the driving state of the vehicle, and the target output ratio of the engine and the target speed ratio of the transmission are set based on the target drive torque of the vehicle. In the vehicle driving force control device comprising driving force distribution setting means for setting the driving force distribution of the vehicle, traveling state detecting means for detecting the traveling state of the host vehicle and a preceding vehicle during the traveling, and the traveling state Driving force distribution changing means for changing the driving force distribution based on the driving force distribution is provided.

  When detecting that the own vehicle is decelerating and the preceding vehicle is accelerating, the driving force distribution changing means corrects the target gear ratio to the downshift side and sets the target output to the increasing side from the idle. The driving force distribution is modified to be corrected.

  In the present invention, when it is determined that acceleration is necessary and acceleration is necessary depending on the situation of the preceding vehicle in a state where the accelerator is off, not only the gear ratio is corrected on the downshift side but also the engine than the idle Since the driving force is redistributed so that the output increases, the negative driving torque does not increase and the deceleration does not become excessive, thereby causing the driver to feel uncomfortable that the inter-vehicle distance from the preceding vehicle is unnecessarily increased. The inconvenience of giving to can be avoided. Needless to say, the increase in the engine output is within a limit that satisfies the deceleration request.

  Moreover, in addition to correcting the gear ratio to the downshift side in preparation for the next acceleration in advance, the engine output is increased, so that the acceleration can be started promptly without causing a response delay of the transmission or the engine. Can do.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a system configuration of the present invention. The control start switch SW1 detects whether or not to execute vehicle speed control. When the switch SW1 is on, it is determined that vehicle speed control is to be executed. When the switch SW1 is off, the vehicle speed control is stopped. The brake switch SW2 detects whether or not the driver is stepping on the brake pedal. The switch SW2 is turned on when the brake pedal is depressed, and turned off when the brake pedal is released. Inter-vehicle distance sensor 3 functions as a running condition detecting means according to the present invention in this embodiment, for example, detecting the inter-vehicle distance L _A and the relative velocity △ V between the preceding vehicle by a laser radar. The accelerator opening sensor 5 detects the accelerator depression amount APO of the driver. The vehicle speed sensor 6 detects the actual vehicle speed aVSP of the vehicle from the number of rotations of the tire. The engine speed sensor 7 detects the engine speed aNE from the engine ignition signal.

  In this embodiment, the vehicle speed control device 20 has functions as target drive torque setting means, drive force distribution setting means, and drive force distribution change means according to the present invention. Each cycle (for example, about 10 ms) fetches various signals representative of the driving state from the control start switch SW1, brake switch SW2, inter-vehicle distance sensor 3, accelerator opening sensor 5, vehicle speed sensor 6, engine speed sensor 7, Command values are output to the engine control device 8 and the transmission control device 9. As shown in FIG. 1, the vehicle speed control device 20 includes a control start determination unit 30, a target vehicle speed calculation unit 40, a vehicle speed control unit 50, an actual gear ratio calculation unit 60, and a driving force distribution unit that are configured in the form of a microcomputer software. 70, a driving force redistribution coefficient calculation unit 80, and a driving force redistribution permission unit 90 are provided.

  The vehicle speed control device 20 controls the vehicle speed by using a throttle and a transmission. The engine control device 8 outputs a throttle opening signal to the throttle actuator 10 based on the throttle opening command value cTVO output from the vehicle speed control device 20. The throttle actuator 10 adjusts the throttle valve opening of the engine according to the throttle opening signal. The transmission control device 9 adjusts the transmission gear ratio based on the transmission gear ratio command value cRATIO output from the vehicle speed control device 20.

  The operation of the control start determination unit 30 will be described based on the flowchart shown in FIG. In the following flowcharts and descriptions, the process step number is represented by a numeral indicated with a symbol S.

  First, a signal from the control start switch SW1 is taken, and when the switch SW1 is in the OFF state, the control execution flag fSTART is set to 0 and the processing is ended (S1 to S2). When the flag is 0, the vehicle speed control is stopped. When the control start switch SW1 is in the ON state, a signal from the brake switch SW2 is taken (S3). If the brake switch SW2 is off, the control execution flag fSTART is set to 1 (S4). When the flag is 1, control is executed. When the brake switch SW2 is on, the control execution flag fSTART is set to 0.

  When the driver is stepping on the brake pedal, the flag a is set to 0 and the control is stopped because the actual vehicle speed aVSP cannot be made to follow the target vehicle speed tVSP with the throttle opening and the gear ratio. The control execution flag fSTART is output from the vehicle speed control device 20 to the engine control device 8 and the transmission control device 9, and the engine control device 8 and the transmission control device 9 are controlled as follows according to the flag. When the control execution flag fSTART is 1, the engine control device 8 determines that the vehicle speed control is being executed, and sets the throttle actuator 10 so that the throttle opening is based on the throttle opening command value cTVO output from the vehicle speed control device 20. Control. When the control execution flag fSTART is 0, the engine control device 8 determines that the vehicle speed control is stopped, and controls the throttle actuator 10 to output a throttle opening corresponding to the accelerator depression amount APO.

  Similarly, when the control execution flag fSTART is 1, the transmission control device 9 determines that the vehicle speed control is being executed, and sets the gear ratio in the gear ratio command value cRATIO output from the vehicle speed control device 20. When the control execution flag fSTART is 0, the transmission control device 9 determines that the vehicle speed control is stopped, and sets the gear ratio according to the accelerator depression amount APO and the actual vehicle speed aVSP.

As shown in FIG. 3, the driving force redistribution coefficient calculation unit 80 includes an inter-vehicle distance coefficient calculation unit 81, a relative speed coefficient calculation unit 82, and a distribution coefficient limit unit 83, and the actual vehicle speed aVSP, the inter-vehicle distance LA, and the relative speed Δ Based on V, the driving force redistribution coefficient W ₁ is calculated. Vehicle distance coefficient calculation unit 81 determines the inter-vehicle distance coefficient W _L based on the actual vehicle speed aVSP and headway distance L _A. For example, determine the W ₁ from the map shown in FIG. 4, to determine the inter-vehicle distance coefficient W _L by the following equation (1).

W _L = W ₁ × K _W1 (1)
Here, K _W1 is a gain for setting how sensitively the driving force is redistributed with respect to the inter-vehicle distance, and is a variable value weighted by the driver according to preference.

Relative velocity conversion coefficient computing unit 82 determines the relative speed coefficient W △ _V, the based on the relative velocity △ V. For example, determine the W ₂ from the map shown in FIG. 5, to determine the relative speed coefficient W △ _V from the following equation (2).

WΔ _V = W ₂ × K _W2 (2)
Here, K _W2 is a gain for setting how sensitively the driving force is redistributed with respect to the relative speed, and is a variable value weighted by the driver according to preference.

For example, K _W1 = 4 and K _W2 = 1 are set when acceleration is most responsive when the inter-vehicle distance is long and it is not necessary to increase the response with respect to the relative speed.

  The distribution coefficient limit unit 85 limits W with the maximum value Wmax and the minimum value Wmin. For example, Wmax = 5 and Wmin = 1.

  From the above, the driving force redistribution coefficient W is calculated from the following equation.

W = W _L + WΔ _V (3)
FIG. 6 is a flowchart for explaining the operation of the driving force redistribution permission unit. In S1, it is determined whether the accelerator is OFF or ON by taking in the signal from the accelerator sensor. If the accelerator is OFF, proceed to S2. If the accelerator is ON, the process proceeds to S5, and the driving force redistribution permission flag fRedist_TDR is set to zero. In S2, a signal from the inter-vehicle distance sensor is taken to determine whether the actual inter-vehicle distance is longer than the target inter-vehicle distance. If it is determined that the actual inter-vehicle distance is longer than the target inter-vehicle distance, the process proceeds to S3. If it is determined that the actual inter-vehicle distance is shorter than the target inter-vehicle distance, the process proceeds to S5 and the driving force redistribution permission flag fRedist_TDR is set to zero. The target inter-vehicle distance is an inter-vehicle distance arbitrarily set by the driver. In this way, when the actual inter-vehicle distance is short to some extent, the reason why the driving force is not redistributed is because there are many opportunities for driving operations to actively increase the inter-vehicle distance under such conditions. .

  In S3, a signal from the inter-vehicle distance sensor is taken to determine whether the relative speed is positive. However, the relative speed here is the value obtained by subtracting the vehicle speed of the preceding vehicle from the speed of the preceding vehicle.If the preceding vehicle is traveling at a higher speed than the own vehicle, the relative speed is positive, and the preceding vehicle is more than the own vehicle. When traveling at a slow speed, the relative speed shall be negative. If it is determined that the relative speed is positive, the process proceeds to S4. If it is determined that the relative speed is negative, there is no need to perform the driving force redistribution by this control, so the process proceeds to S5 and the driving force redistribution permission flag fRedist_TDR is set to zero. When the relative speed is positive, the inter-vehicle distance is increasing. Therefore, the driving force redistribution permission flag fRedist_TDR is set to 1 in S4 in order to enable the driving force redistribution by this control.

  The target vehicle speed calculation unit 40 includes a target acceleration determination unit 41 and an integration processing unit 42, as shown in FIG.

  The target acceleration determining unit 41 determines the target acceleration tACC based on the map shown in FIG. 8 from the accelerator depression amount APO and the target vehicle speed tVSP calculated by the integration processing unit. As shown in FIG. 8, the target acceleration tACC increases as the accelerator depression amount increases. Also, in order to cope with the fact that the higher the vehicle speed, the greater the running resistance and the lower the realizable acceleration, in FIG. 8, the target acceleration is set to be smaller as the vehicle speed is higher if the accelerator is depressed the same. .

  The integration processing unit 42 calculates the target vehicle speed tVSP based on the control execution flag fSTART, the actual vehicle speed aVSP, and the target acceleration tACC. FIG. 9 shows the processing contents of the integration processing unit 42. When the control execution flag fSTART is 0, that is, when the control start switch SWl is off or the brake pedal is depressed, the target vehicle speed tVSP and the previous value of tVSP are initialized with the actual vehicle speed aVSP (S1 to S2). When the control execution flag fSTART is 1, that is, when the control start switch SWl is on and the brake pedal is not depressed, the target acceleration tACC is added to the previous value of tVSP to obtain the target vehicle speed tVSP. After the target vehicle speed tVSP is calculated, the previous value of tVSP is updated with the target vehicle speed tVSP (S1 to S3). The target vehicle speed tVSP is output to the vehicle speed control unit 50.

FIG. 10 shows the configuration of the vehicle speed control unit 50. The vehicle speed control unit 50 includes a two-degree-of-freedom control system including a feedforward control unit (hereinafter referred to as an F / F control unit) and a feedback control unit (hereinafter referred to as an F / B control unit). The vehicle speed control unit 50 uses the F / F control unit and the F / B control unit so that the transfer characteristic when the target vehicle speed tVSP is input and the output is the actual vehicle speed aVSP is the transfer characteristic of the reference model 52 in FIG. Control. The transfer function G _T (s) of the reference model 52 is expressed by the following equation (4).

すなわち、規範モデル52の伝達特性G_T(s)は時定数τ_Hの1次のローパスフィルタと無駄時間L_Vからなる。ここでsはラプラス演算子を表す。

In other words, the transfer characteristic G _T of the reference model 52 (s) is composed of dead time and first-order low-pass filter time constant τ _H L _V. Here, s represents a Laplace operator.

  The vehicle model to be controlled is modeled using the drive torque command value as the manipulated variable and the vehicle speed as the controlled variable, so that the behavior of the vehicle's powertrain can be represented by a simple nonlinear model shown in FIG. 5).

ここで、Mは車両質量、Rtはタイヤ動半径、Lpは無駄時間を表す。駆動トルク指令値を入力とし、車速を出力とする車両モデルは積分特性となる。ただし、制御対象の特性にはパワートレイン系の遅れにより無駄時間も含まれることになり、使用するアクチュエータやエンジンによって無駄時間Lpは変化する。

Here, M represents the vehicle mass, Rt represents the tire moving radius, and Lp represents the dead time. A vehicle model having the drive torque command value as input and the vehicle speed as output has integral characteristics. However, the characteristics to be controlled include a dead time due to a delay in the power train system, and the dead time Lp varies depending on the actuator and engine used.

The F / F control unit consists of a phase compensator 51, and the F / F command value indicates the response characteristics of the control target when the target vehicle speed tVSP is input and the actual vehicle speed aVSP is output. Have elements and match the characteristics of the predetermined transfer characteristic G _T (s). If the dead time of the controlled object is ignored and the transfer characteristic G _T (s) of the reference model 52 is a first-order low-pass filter with a time constant τ _H , the transfer characteristic Gc (s) of the phase compensator 51 is It is represented by (6).

F/B制御部は、規範モデル52とフィードバック補償器53より構成される。規範モデル52から出力される規範応答Vrefと実車速aVSPとの差をフィードバック補償器53の入力とし、F/B指令値を算出する。F/B指令値により外乱やモデル化誤差による影響を抑える。フィードバック補償器の一例として図10に示されるように比例ゲインK_Pと積分ゲインK_IからなるPI補償器がある。

The F / B control unit includes a reference model 52 and a feedback compensator 53. The difference between the reference response Vref output from the reference model 52 and the actual vehicle speed aVSP is input to the feedback compensator 53, and the F / B command value is calculated. F / B command value suppresses the influence of disturbance and modeling error. There are PI compensator consist proportional gain K _P and the integral gain K _I as shown in FIG. 10 as an example of a feedback compensator.

  The actual gear ratio calculation unit 60 calculates the actual gear ratio aRATIO from the actual vehicle speed aVSP and the engine speed aNE according to the following equation (7). Gf is the final gear ratio of the vehicle, and Rt is the tire moving radius.

駆動力配分部70について図12に基づいて説明する。駆動力配分部70は、変速比指令値設定部71、エンジントルク指令値算出部72、変速比指令値切替え部73、スロットル開度指令値算出部74から構成され、実車速aVSP、駆動トルク指令値cTDR、実変速比aRATIO、エンジン回転数aNE、駆動力再配分係数W、駆動力再配分許可フラグfRedist_TDRを入力として変速比指令値cRATIOとスロットル開度指令値cTVOを算出する。

The driving force distribution unit 70 will be described with reference to FIG. The driving force distribution unit 70 includes a gear ratio command value setting unit 71, an engine torque command value calculation unit 72, a gear ratio command value switching unit 73, and a throttle opening command value calculation unit 74. The actual vehicle speed aVSP, the drive torque command The gear ratio command value cRATIO and the throttle opening command value cTVO are calculated with the value cTDR, actual gear ratio aRATIO, engine speed aNE, driving force redistribution coefficient W, and driving force redistribution permission flag fRedist_TDR as inputs.

  The gear ratio command value setting unit 71 determines a gear ratio command value 1: cRATIO1 from the drive torque command value cTDR and the actual vehicle speed aVSP using the map shown in FIG. FIG. 13 shows a map when a continuously variable transmission is used.

  Next, gear ratio command value 2: cRATIO2 is calculated from the following equation (8) based on cRATIO1 and driving force redistribution coefficient W.

cRATIO2 = cRATIO1 x W (8)
The engine torque command value calculation unit 72 calculates the engine torque command value cTE from the drive torque command value cTDR and the actual gear ratio aRATIO according to the following equation (9).

変速比指令値切替え部73は、図14に示すように駆動力再配分許可フラグfRedist_TDRに従い変速比指令値cRATIOの切替えを行う。fRedist_TDRが1の場合、cRATIOをcRATIO2とする(S1〜S3)。fRedistTDRが0の場合、cRATIOをcRATIO1とする(S1〜S2)。

The gear ratio command value switching unit 73 switches the gear ratio command value cRATIO according to the driving force redistribution permission flag fRedist_TDR as shown in FIG. When fRedist_TDR is 1, cRATIO is set to cRATIO2 (S1 to S3). When fRedistTDR is 0, cRATIO is set to cRATIO1 (S1 to S2).

  The throttle opening command value calculation unit 74 calculates the throttle opening command value cTVO from the engine torque command value cTE and the engine speed aNE using the engine total performance map shown in FIG.

  The gear ratio command value cRATIO calculated by the driving force distribution unit 70 is output to the transmission control device 9 as shown in FIG. The throttle opening command value cTVO is output to the engine control device 8.

FIG. 16 shows vehicle speed control characteristics according to this embodiment in comparison with the prior art. In the figure, the solid line shows the characteristics according to the conventional technology.In this case, the preceding vehicle, which was decelerating at the same time as the host vehicle, accelerates at time t1, and the inter-vehicle distance L _A exceeds the predetermined value at time t2. Since it has become larger, a downshift of the gear ratio is started according to the inter-vehicle distance. At time t3, the host vehicle is in a traveling state where the accelerator is depressed to accelerate following the preceding vehicle. However, since the downshift is started at time t2 while the throttle opening is fully closed, the negative driving torque becomes excessive and the deceleration increases. As a result, the inter-vehicle distance from the preceding vehicle further increases, giving the driver a sense of discomfort that the vehicle is left behind. Further, since the throttle is fully closed, when the driver depresses the accelerator pedal at time t3 to start acceleration, the response of the engine is delayed until the throttle is opened, and the acceleration is delayed.

  In contrast, according to the control of this embodiment, as shown by the one-dot chain line in FIG. 16, a downshift according to the inter-vehicle distance is started at time t2, but at this time, the throttle opening is fully closed. Since it is somewhat open, the negative driving torque is not increased, and in this case, the deceleration is controlled to be substantially constant before and after the downshift. As a result, the distance between the preceding vehicle and the preceding vehicle rapidly expands beyond expectation, and the driver does not feel uncomfortable that the vehicle is left behind. Further, when the driver attempts to start acceleration by depressing the accelerator pedal at time t3, the throttle can be opened somewhat, so that the acceleration can be started without delay in response of the engine.

In addition to the above effect, according to this embodiment, since the driving force distribution is changed when the inter-vehicle distance between the host vehicle and the preceding vehicle is larger than a predetermined value set by the driver, the inter-vehicle distance is It is possible to suppress the improvement of the acceleration response when there are few and to ensure the driving performance faithful to the driver's intention. (Effect of claim 2)
As shown in FIG. 4 to FIG. 5, the greater the distance between the vehicle and the preceding vehicle, the smaller the vehicle speed of the own vehicle, or the greater the vehicle speed of the preceding vehicle, Since the correction amount of the target output is increased, the degree of acceleration demand of the driver is predicted according to the situation of the preceding vehicle, and the driving force is redistributed in advance in preparation for the accelerator pedal depressing operation after deceleration. This makes it possible to obtain acceleration performance suitable for the situation of the preceding vehicle. (Effects of claims 3 to 5)
Further, when the correction amount of the target output is increased with respect to the inter-vehicle distance and relative speed with respect to the preceding vehicle, the gain is set to a variable value set by the driver, so that the target output change with respect to the inter-vehicle distance and relative speed is changed. Can be set according to the driver's preference, and the drivability of the vehicle can be further improved. (Effects of claims 6-7)

The system block diagram of one Embodiment of this invention. The flowchart which shows operation | movement of the control start determination part of embodiment. The logic block diagram of the driving force redistribution coefficient calculation part of embodiment. In the control of the embodiment, the characteristic diagram of maps providing a driving force redistribution coefficients W ₁ from the actual vehicle speed and the inter-vehicle distance. In the control of the embodiment, the characteristic diagram of maps providing a relative speed coefficient W ₂ based on the relative speed between the preceding vehicle and the subject vehicle. The flowchart explaining operation | movement of the driving force redistribution permission part of embodiment. The logical block diagram of the target vehicle speed calculation part of embodiment. FIG. 6 is a characteristic diagram of a map that gives a target acceleration tACC from an actual vehicle speed and an accelerator depression amount in the control of the embodiment. The flowchart which shows operation | movement of the integration process part of embodiment. The logical block diagram of the vehicle speed control part of embodiment. Explanatory drawing of the simple nonlinear model which shows the behavior of the power train of a vehicle by making a drive torque command value into an operation amount and a vehicle speed as a control amount. The logical block diagram of the driving force distribution part of embodiment. The characteristic diagram of the map which provides a gear ratio command value from drive torque designation | designated value and an actual vehicle speed in control of embodiment. The flowchart explaining operation | movement of the gear ratio command value switching part of embodiment. FIG. 6 is a characteristic diagram of an engine total performance map that gives a throttle opening command value cTVO from an engine torque command value and an engine speed in the control of the embodiment. The timing chart which showed the vehicle speed control characteristic by embodiment in comparison with a prior art.

Explanation of symbols

3 Inter-vehicle distance sensor (running state detection means)
8 Engine control device 9 Transmission control device 20 Engine control device 70 Driving force distribution unit 80 Driving force redistribution coefficient calculation unit

Claims (7)

Target driving torque setting means for setting the target driving torque of the vehicle based on the driving state of the vehicle, and distribution of the driving force of the vehicle by setting the target output of the engine and the target speed ratio of the transmission based on the target driving torque of the vehicle A driving force control device for a vehicle comprising driving force distribution setting means for setting
Traveling state detection means for detecting the traveling state of the vehicle and the preceding vehicle during the traveling;
Driving force distribution changing means for changing the driving force distribution based on the running state,
When detecting that the own vehicle is decelerating and the preceding vehicle is accelerating, the driving force distribution changing means corrects the target gear ratio to the downshift side and sets the target output to the increasing side from the idle. A driving force control apparatus for a vehicle, wherein the driving force distribution is changed by correction.   The vehicle driving force control device according to claim 1, wherein the driving force distribution changing unit changes the driving force distribution when an inter-vehicle distance between the host vehicle and a preceding vehicle is larger than a predetermined value.   The vehicle driving force control device according to claim 1, wherein the driving force distribution changing unit increases the correction amount of the target output as the inter-vehicle distance between the host vehicle and the preceding vehicle increases.   The vehicle driving force control device according to claim 1, wherein the driving force distribution changing unit increases the correction amount of the target output as the vehicle speed of the host vehicle decreases.   The vehicle driving force control device according to claim 1, wherein the driving force distribution changing unit increases the correction amount of the target output as the vehicle speed of the preceding vehicle increases.   The vehicle driving force control device according to claim 2, wherein the predetermined value of the inter-vehicle distance is a variable value set by a driver.   The vehicle driving force control apparatus according to any one of claims 3 to 5, wherein a gain for increasing the correction amount of the target output is a variable value set by a driver.

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