JP6170357B2 - Vehicle travel control device - Google Patents

Description

  The present invention relates to a vehicle travel control device that outputs a target deceleration by a plurality of braking systems such as a regenerative brake and a friction brake (main brake).

  In recent years, radar means such as millimeter wave radar and infrared laser radar, imaging means such as a stereo camera and a monocular camera, or the combination of these radar means and imaging means recognizes information outside the vehicle in front of the vehicle lane. A cruise control with an inter-vehicle distance control (ACC: Adaptive Cruise Control) device that selectively performs follow-up running control and constant speed running control according to the state of capture of a preceding vehicle at has been proposed and put into practical use. When such a cruise control device is applied to, for example, a hybrid vehicle having an engine and an electric motor as disclosed in JP-T-2011-504432 (hereinafter referred to as Patent Document 1), a target deceleration is output. In some cases, the regenerative brake and the main brake may operate together.

Special table 2011-504432 gazette

  For example, when the target deceleration Dect based on the driving state of the vehicle as shown by the broken line in FIG. 5A is to be output, the regenerative brake target deceleration Dect2 calculated based on the target deceleration Dect is as shown in FIG. The regenerative brake target deceleration Dect2 is calculated as shown by the broken line in (b), and is actually delayed and output as the regenerative brake deceleration Dec2 shown by the solid line in FIG. The Similarly, the main brake target deceleration Dect1 calculated based on the target deceleration Dect is calculated as shown by the broken line in FIG. 5C, and this main brake target deceleration Dect1 actually has a response delay. Therefore, the main brake deceleration Dec1 is output with a delay as indicated by the solid line in FIG. Accordingly, since the actual deceleration Dec output with respect to the target deceleration Dect is the sum of the regenerative brake deceleration Dec2 and the main brake deceleration Dec1, the output is delayed as shown by the solid line in FIG. Will be. Here, the sum of the regenerative brake deceleration Dec2 and the main brake deceleration Dec1 indicates that the peak value of the regenerative brake deceleration Dec2 and the main brake deceleration Dec1 value are in some circumstances (for example, the structure of the regenerative brake and the main brake). 5), the peak value of the actual deceleration Dec becomes larger than the peak value of the target deceleration Dect, as shown in FIG. 5 (a). This causes a problem that the driver feels uncomfortable and that smooth running control cannot be performed.

  The present invention has been made in view of the above circumstances, and even when a plurality of braking systems such as a regenerative brake and a main brake are operated, the braking timing from each braking system is appropriately controlled without causing the driver to feel uncomfortable. Another object of the present invention is to provide a vehicle travel control device that can accurately generate a target deceleration.

  A vehicle travel control apparatus according to an aspect of the present invention sets a target acceleration and a target deceleration based on a driving state of the vehicle, and outputs the first deceleration unit and the first deceleration when the target deceleration is output. In a vehicle travel control device that operates a second speed reduction means different from the means, a first output outputted from the first speed reduction means with a first response delay based on at least the target deceleration. A first target deceleration calculating means for calculating a target deceleration; and a second response delay which is delayed from the second deceleration means based on at least the target deceleration. And second target deceleration calculating means for calculating a second target deceleration lower than the first target deceleration to be output.

  According to the vehicle travel control device of the present invention, even when a plurality of braking systems such as a regenerative brake and a main brake are operated, the braking timing from each braking system is appropriately controlled without causing the driver to feel uncomfortable. It is possible to generate the target deceleration with high accuracy.

1 is a system configuration diagram of a hybrid vehicle according to an embodiment of the present invention. It is a flowchart of the cruise control which concerns on one Embodiment of this invention. It is a flowchart of the deceleration control which concerns on one Embodiment of this invention. FIG. 4A is an explanatory diagram of a target deceleration and an actual deceleration according to an embodiment of the present invention, FIG. 4A is an explanatory diagram of the target deceleration and the actual deceleration, and FIG. 4B is a regenerative brake target deceleration. FIG. 4C is an explanatory diagram of the main brake target deceleration and the main brake deceleration. FIG. 5A is an explanatory diagram of the target deceleration and the actual deceleration according to the prior art, FIG. 5A is an explanatory diagram of the target deceleration and the actual deceleration, and FIG. 5B is a graph showing the regenerative brake target deceleration and the regenerative brake deceleration. FIG. 5C is an explanatory diagram of the main brake target deceleration and the main brake deceleration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a power unit of a hybrid vehicle. This power unit 1 is, for example, a series / parallel type power unit that uses an engine 2 and an electric motor 3 as a drive source. It is mounted on a vehicle such as an automobile having a cruise control with distance control (ACC: Adaptive Cruise Control) function.

  The power unit 1 has an automatic transmission 5 incorporating an electric motor 3, and the automatic transmission 5 is connected to the engine 2 to constitute a main part.

  The automatic transmission 5 has a torque converter 6 connected to the output shaft 2a of the engine 2. The torque converter 6 includes a continuously variable transmission (CVT) 8 as an automatic transmission and a drive shaft on the electric motor 3 side. The drive shaft on the engine 2 side is connected via a forward / reverse switching device 7 that can be switched and forward / reversely switched.

  The CVT 8 has a primary shaft 9a connected to the forward / reverse switching device 7 and a secondary shaft 10a parallel to the primary shaft 9a. The primary pulley 9 and the secondary pulley 10 are respectively connected to the shafts 9a and 10a. It is worn. Further, a winding type driving force transmission member 11 made of a belt or a chain is wound around the pulleys 9 and 10. The CVT 8 can be arbitrarily set between the primary shaft 9a and the secondary shaft 10a by changing the winding radius of the driving force transmission member 11 with respect to the pulleys 9 and 10 (that is, by changing the pulley ratio). Thus, it is possible to transmit the driving force that has been shifted at a gear ratio of 1 to 5.

  A drive shaft 15 connected to drive wheels (not shown) is connected to the secondary shaft 10a via a reduction gear mechanism 16. The reduction gear mechanism 16 includes a reduction gear shaft 17 parallel to the secondary shaft 10a and the drive shaft 15, a first gear train 18 interposed between the reduction gear shaft 17 and the secondary shaft 10a, and a reduction gear shaft. 17 and a second gear train 19 interposed between the drive shaft 15 and the second gear train 19. Further, the reduction gear mechanism 16 is provided with a clutch 20 that engages or releases between the first gear train 18 and the reduction gear shaft 17. When the clutch 20 is in the engaged state, the reduction gear mechanism 16 is a secondary gear. A driving force can be transmitted between the shaft 10 a and the drive shaft 15.

  An electric motor 3 is connected to the end of the primary shaft 9a opposite to the engine 2. A battery 26 constituting a main power source of the vehicle is connected to the electric motor 3 via an inverter 25. The inverter 25 converts DC power from the battery 26 into AC power and drives the electric motor 3. In addition, the inverter 25 generates electric power with the electric motor 3 by using the electric motor 3 as a generator during regenerative braking or the like based on a target deceleration (regenerative brake target deceleration) Dect2 described later from the hybrid ECU 30. The AC power thus converted is converted into DC power and the battery 26 is charged. As described above, the electric motor 3 is provided as the second reduction means.

  The engine 2, the electric motor 3, the battery 26, and the automatic transmission 5 are respectively an engine control unit (engine ECU) 31, a motor control unit (motor ECU) 32, a battery management unit (battery ECU) 33, and a transmission control unit (transmission). ECU) 34. In addition to a hydraulic unit equipped with a pressure source, a pressure reducing valve, a pressure increasing valve, etc., in addition to the operation of the brake pedal by the driver, each wheel cylinder (not shown) of each wheel according to an input signal The brake drive unit 36 that constitutes the first deceleration means that can independently introduce the brake hydraulic pressure is controlled by a brake control unit (brake ECU) 35. In the present embodiment, the friction brake of each wheel output through the brake drive unit 36 is referred to as a main brake.

  The control units such as the ECUs 31 to 35 described above and various sensors / switches 50 are connected to a central hybrid control unit (hybrid ECU) 30 that performs overall control of the entire system. Each of the ECUs 30 to 35 including the hybrid ECU 30 is configured to include various interfaces and peripheral devices with a microcomputer at the center, and is connected to be capable of bidirectional communication via a communication line such as a CAN (Controller Area Network). Control information and sensing information related to the operating state of the controlled object are communicated with each other.

  When the functions of the ECUs 31 to 35 are outlined, the engine ECU 31 receives a control command from the hybrid ECU 30, and based on signals from sensors provided in the engine 2, the throttle opening, ignition timing, fuel injection amount, etc. Calculate the parameters. Then, the actuators are driven by the control signals of these parameters, and the operation state of the engine 2 is controlled so that the output of the engine 2 matches the control command value.

  The motor ECU 32 receives a control command from the hybrid ECU 30 and controls the electric motor 3 via the inverter 25. Based on information such as the number of revolutions of the electric motor 3, voltage and current, the current to the inverter 25 is controlled. A command or voltage command is output, and the electric motor 3 is controlled so that the output of the electric motor 3 matches the control command value.

  The battery ECU 33 determines the battery state based on the remaining capacity indicated by the state of charge (SOC) of the battery 26, the input / output possible power amount indicated by the maximum input / output power in the battery 26, the degree of deterioration of the battery 26, and the like. It manages the grasping, controlling the cooling and charging of the battery 26 after grasping the battery state, detecting an abnormality, a protection operation at the time of detecting the abnormality, and the like.

  The transmission ECU 34 receives a control command from the hybrid ECU 30, determines the gear ratio of the CVT 8, and controls the gear ratio to an appropriate gear ratio according to the driving state. Further, the transmission ECU 34 switches the traveling mode by, for example, receiving a control command from the hybrid ECU 30 and controlling the forward / reverse switching device 7, the clutch 20, and the like.

  That is, in the engine travel mode, the transmission ECU 34 cuts off the driving force transmission between the engine 2 and the electric motor 3 by the forward / reverse switching device 7, fastens the clutch 20, and reduces the driving force from the engine 2 to the front and rear. The signal is transmitted to the CVT 8 via the advance switching device 7, and is shifted to a predetermined speed by the CVT 8 and transmitted to the drive wheel 15.

  Further, in the motor travel mode, the transmission ECU 34 disconnects the driving force transmission between the engine 2 and the electric motor 3 by the forward / reverse switching device 7, fastens the clutch 20, and drives the driving force from the electric motor 3. Is transmitted to the CVT 8, and the CVT 8 is shifted to a predetermined speed and transmitted to the drive wheel 15.

  In the hybrid travel mode, the transmission ECU 34 connects the driving force transmission between the engine 2 and the electric motor 3 by the forward / reverse switching device 7, fastens the clutch 20, and connects the engine 2 and the electric motor 3. The driving force is transmitted to the CVT 8, and a predetermined speed is changed at the CVT 8 and transmitted to the drive wheel 15.

  Here, in the above-described motor travel mode and hybrid travel mode, regenerative braking can be generated by causing the electric motor 3 to perform a regenerative operation during decelerating travel.

  The brake ECU 35 can realize a control using a brake force such as a known antilock brake system for preventing wheel lock and anti-slip control. Further, a target deceleration (main brake target deceleration) Dec 1 is input from the hybrid ECU 30, and based on the main brake target deceleration Dec 1, the target brake fluid pressure for each wheel is set in consideration of the specifications of the vehicle. The brake force is generated to cause the vehicle to decelerate.

  On the other hand, as one of the driving support functions based on the environment outside the vehicle, the hybrid ECU 30 selectively performs the following traveling control and the constant speed traveling control in accordance with the capturing state of the preceding vehicle in front of the own vehicle traveling lane. A stereo camera unit 40 for realizing a cruise control with an inter-vehicle distance control (ACC: Adaptive Cruise Control) function is connected.

  The stereo camera unit 40 includes a stereo camera 41 and a preview control unit (preview ECU) 42.

  The stereo camera 41 includes a pair of left and right CCD cameras 41L and 41R using a solid-state imaging device such as a charge coupled device (CCD) as a stereo optical system. These CCD cameras 41L and 41R are each mounted at a certain interval in front of the ceiling in the vehicle interior, and take a stereo image of objects outside the vehicle from different viewpoints.

  The preview ECU 42 is constituted by, for example, a microprocessor equipped with a three-dimensional image processing engine, image recognition software, vehicle control software, and the like. Image information from the stereo camera 41 is input to the preview ECU 42 and, for example, the host vehicle speed V is input from the transmission ECU 34. The preview ECU 42 performs, for example, a stereo matching process on a group of pixels of a set of images (stereo images) captured by the stereo camera 41, and performs a grouping process on the obtained image information, so that a white line in front of the vehicle Recognizes three-dimensional objects. The preview ECU 42 estimates the own vehicle travel path based on the recognized white line, solid object, and the like, and detects a preceding vehicle on the own vehicle travel path. When the preceding ECU detects a preceding vehicle, the preceding vehicle information includes the preceding vehicle distance D (= inter-vehicle distance), the preceding vehicle speed Vf (= (change ratio of the inter-vehicle distance D) + (own vehicle speed). V)), the preceding vehicle acceleration af (= differential value of the preceding vehicle speed Vf) and the like.

  The preview ECU 42 receives various setting information such as a set vehicle speed Vset and an inter-vehicle distance mode (for example, “long”, “medium”, “short”) through an ACC switch (not shown), for example.

  When the ACC function is turned on, for example, according to the flowchart of FIG. 2 to be described later, the preview ECU 42 performs traveling control so that the set vehicle speed Vset is set when there is no preceding vehicle, and the preceding vehicle When there is, the travel control is performed so that the set inter-vehicle distance is obtained.

  The ACC control (cruise control) of the present invention will be described below with reference to the flowchart of FIG. This flowchart is executed when the ACC function is turned on.

  First, in step (hereinafter abbreviated as “S”) 101, necessary parameters, that is, various preceding vehicle information, own vehicle speed V, set vehicle speed Vset, set inter-vehicle distance mode, and the like are read.

  Next, proceeding to S102, the preview ECU 42 calculates a first target acceleration a1 for converging the host vehicle speed V to the set vehicle speed Vset. That is, for example, the preview ECU 42 calculates a vehicle speed deviation ΔV (= Vset−V) between the host vehicle speed V and the set vehicle speed Vset, and calculates a first target acceleration a1 with reference to a preset map or the like.

  Next, the process proceeds to S103, where it is determined whether there is a preceding vehicle on the own vehicle traveling path. If there is a preceding vehicle, the process proceeds to S104, and the inter-vehicle distance D is set to the target distance Dtrg according to the inter-vehicle distance mode. A second target acceleration a2 for convergence is calculated.

  The calculation of the second target acceleration a2 is executed as follows, for example. First, a target map Dtrg corresponding to the host vehicle speed V is set with reference to a map set in advance for each inter-vehicle distance mode. Then, a distance deviation ΔD (= Dtrg−D) between the follow target distance Dtrg and the inter-vehicle distance D is calculated, and a relative speed Vfrel (= Vf−V) between the preceding vehicle speed Vf and the own vehicle speed V is calculated. The second target acceleration a2 is calculated with reference to a preset map or the like using as a parameter.

  Next, the process proceeds to S105, where the larger one of the first target acceleration a1 and the second target acceleration a2 is set as the final (auto-cruise) target acceleration a0 related to ACC.

  If it is determined in S103 that there is no preceding vehicle on the own vehicle travel path, the process proceeds to S105 as it is, and the first (targeted) a1 target acceleration a1 is set as the final (auto cruise) target acceleration a0 related to ACC. Set.

  Then, the process proceeds to S106, in which it is determined whether or not the auto-cruise target acceleration a0 is equal to or greater than a preset threshold value aCH (a0 ≧ aCH: CH is a positive value close to 0, for example). Proceeding to S107, acceleration control is executed.

  In S107, the target driving force Ft corresponding to the auto-cruise target acceleration a0 is set, and when this target driving force Ft is a predetermined low value, the actual driving force Fr becomes the target driving force Ft by the driving force of the electric motor 3. When the target drive force Ft is increased, feedback control is performed so that the actual drive force Fr becomes the target drive force Ft by the drive force of the engine 2 in addition to the drive force by the electric motor 3.

  On the other hand, if the auto-cruise target acceleration a0 is less than the preset threshold value aCH (a0 <aCH) in S106, the process proceeds to S108, where the auto-cruise target acceleration a0 is equal to or less than the preset threshold value aCL (a0). ≦ aCL: CL is a negative value close to 0, for example. If a0 ≦ aCL, the process proceeds to S109, and deceleration control shown in FIG. If the auto cruise target acceleration a0 is larger than the preset threshold value aCL in S108, the program is exited as it is.

Next, the deceleration control executed in S109 described above will be described with reference to the flowchart of FIG.
First, in S201, the regenerative brake target deceleration Dect2 is set as the target deceleration Dect, for example, the auto cruise target acceleration a0 determined as a0 ≦ aCL in S108 described above, and a constant C2 calculated in advance for this target deceleration Dect is set. The regenerative brake target deceleration Dect2 is calculated by multiplication.

  Here, the pre-calculated constant C2 is a value that is an addition value with a pre-calculated constant C1 described later (that is, C1 + C2 = 1), and a value smaller than 0.5, and the remaining battery power The value is set closer to 0.5 as the capacity SOC is smaller.

  Then, this regenerative brake target deceleration Dect2 is output through, for example, a filter having a preset time constant T2 (for example, a first-order lag filter: expressed by the following equation (1)).

1 / (1 + T2 · s) (1)
Here, s is a Laplace operator. Further, the time constant T2 set in advance sufficiently considers the delay of the actual main brake deceleration Dec1 that is output with a delay of the main brake target deceleration Dec 1 described later, and the regenerative brake target deceleration Dec 2 is more The time constant is a large value set in advance so as to be output with a delay. Thus, this S201 shows the function of the 2nd target deceleration calculation means in hybrid ECU30.

  Next, the process proceeds to S202, where the main brake target deceleration Dect1 is set as the target deceleration Dect, for example, the autocruise target acceleration a0 determined as a0 ≦ aCL in S108 described above, and a constant calculated in advance for this target deceleration Dect. The main brake target deceleration Dect1 is calculated by multiplying by C1 (= 1-C2).

  The main brake target deceleration Dect1 is output through, for example, a filter having a preset time constant T1 (for example, a first-order lag filter: expressed by the following equation (2)).

1 / (1 + T1 · s) (2)
Here, the preset time constant T1 sufficiently considers the delay of the actual regenerative brake deceleration Dec2 that is output with a delay of the regenerative brake target deceleration Dec2, and the main brake target deceleration Dect1 is It is a time constant set in advance so that it is output earlier. Thus, this S202 shows the function of the 1st target deceleration calculation means in hybrid ECU30.

As described above, the deceleration control in the present embodiment is executed. In S202 described above, the main brake target deceleration Dect1 is changed to the target deceleration Dect-the predicted regenerative brake deceleration (regenerative brake target deceleration Dect2 When calculating with the actual regenerative brake deceleration Dec2) Dece output with a delay, the predicted regenerative brake deceleration Dece may be obtained as in the following equation (3).
Dece = 1 / (1+ (T2−t2) · s) · Dect2 (3)
Here, t2 is a deceleration response delay time obtained through the electric motor 3, and is a time previously obtained by experiments or the like. Thus, when calculating the main brake target deceleration Dect1, the regenerative brake deceleration Dece that is predicted in consideration of the response delay time t2 of the deceleration obtained through the electric motor 3 is calculated to obtain a more accurate result. The main brake target deceleration Dect1 may be calculated well.

Further, in S202 described above, the main brake target deceleration Dect1 is set to the target deceleration Dect−the predicted regenerative brake deceleration (the actual regenerative brake deceleration Dec2 output with the regenerative brake target deceleration Dec2 being delayed) Dece. In the case of calculation, the predicted regenerative brake deceleration Dece may be obtained as in the following equation (4).
Dece = 1 / (1+ (T2- (t2-t1)). S) .Dect2 (4)
Here, t1 is a response delay time of deceleration obtained through the main brake, and is a time obtained in advance through experiments or the like. In this way, when calculating the main brake target deceleration Dect1, the prediction is made in consideration of the deceleration response delay time t2 obtained through the electric motor 3 and the deceleration response delay time t1 obtained through the main brake. By calculating the regenerative brake deceleration Dece to be performed, the main brake target deceleration Dect1 may be calculated with higher accuracy.

  Thus, according to the embodiment of the present invention, in a hybrid vehicle equipped with cruise control with inter-vehicle distance control, the target acceleration a0 and the target deceleration Dect are set based on the driving state of the vehicle, When outputting with the main brake (main brake deceleration Dec1) by the friction brake and the regenerative brake (regenerative brake deceleration Dec2) by the electric motor 3, the response delay of the regenerative brake deceleration Dec2 is greater than the response delay of the main brake deceleration Dec1. Is set to be larger (delayed).

  For this reason, when the target deceleration Dect based on the driving state of the vehicle as shown by the broken line in FIG. 4A is to be output, the regenerative brake target deceleration Dect2 (FIG. 4) calculated based on the target deceleration Dect or the like. The broken line (b) is output after being largely delayed in consideration of the response delay of the main brake, as indicated by the regenerative brake deceleration Dec2 of the solid line in FIG. Further, the main brake target deceleration Dect1 calculated based on the target deceleration Dect shown by the broken line in FIG. 4C is the regenerative brake, as the main brake deceleration Dec1 shown by the solid line in FIG. The response delay is smaller than that of the deceleration Dec2 and output. Accordingly, since the actual deceleration Dec output with respect to the target deceleration Dect is the sum of the regenerative brake deceleration Dec2 and the main brake deceleration Dec1, the output is delayed as shown by the solid line in FIG. However, since the peak value of the regenerative brake deceleration Dec2 and the peak value of the main brake deceleration Dec1 are separated from each other, the peak of the actual deceleration Dec as shown by ΔDecp in FIG. The value and the peak value of the target deceleration Dect are substantially equal (preventing an excessive increase as in the conventional ΔDecp as shown in FIG. 5A), causing a sudden deceleration and making the driver uncomfortable. Smooth running control can be performed without giving.

  In the embodiment of the present invention, the response delay of the regenerative brake with a small deceleration is set larger than the response delay of the main brake. Therefore, even when the main brake is operated to ensure the stability of the vehicle, etc. Prompt response by the main brake is possible.

  Note that the configuration of the hybrid vehicle according to the present embodiment is merely an example, and the configuration of the hybrid vehicle using other configurations (such as a clutch and an automatic transmission) may be used.

DESCRIPTION OF SYMBOLS 1 Power unit 2 Engine 3 Electric motor (2nd deceleration means)
5 Automatic transmission 7 Forward / reverse switching device 8 CVT
9 Primary pulley 10 Secondary pulley 20 Clutch 25 Inverter 26 Battery 30 Hybrid ECU (first target deceleration calculation means, second target deceleration calculation means)
31 Engine ECU
32 motor ECU
33 Battery ECU
34 Transmission ECU
35 Brake ECU
36 Brake drive (first reduction means)
40 Stereo camera unit 41 Stereo camera 42 Preview ECU
50 Sensors and switches

Claims (5)

The target acceleration and the target deceleration are set based on the driving state of the vehicle, and the first deceleration unit and the second deceleration unit different from the first deceleration unit are operated when the target deceleration is output. In a vehicle travel control device,
First target deceleration calculation means for calculating a first target deceleration output with a first response delay from the first deceleration means based on at least the target deceleration;
At least based on the target deceleration, the second deceleration means having a second response delay later than the first response delay is output, the first second lower than the target deceleration Second target deceleration calculating means for calculating the target deceleration of
Equipped with a,
The second response delay is set larger than the first response delay so that the peak value of the target deceleration and the peak value of the actual deceleration are substantially equal.
The vehicle travel control apparatus according to claim 1, wherein the first target deceleration and the second target deceleration are calculated so that a sum of both is the target deceleration .   2. The vehicle according to claim 1, wherein the first deceleration means is a main brake braking means for generating a friction deceleration, and the second deceleration means is a regenerative brake braking means for generating a regeneration deceleration. Travel control device. At least one of the first target deceleration and the second target deceleration is output from each deceleration means through a filter having a predetermined time constant,
The vehicle travel control apparatus according to claim 1 or 2, wherein the second response delay is made larger than the first response delay by setting the time constant.   The first target deceleration calculation means includes the second target deceleration including the first target deceleration including the target deceleration and the second response delay output from the second deceleration means. The vehicle travel control device according to claim 1, wherein the vehicle travel control device is calculated based on a predicted value of the vehicle.   The first target deceleration calculation means includes the second target deceleration including the first target deceleration including the target deceleration and the second response delay output from the second deceleration means. 4. The vehicle travel control device according to claim 1, wherein the vehicle travel control device is calculated on the basis of the predicted value and the first response delay. 5.

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