JP4639939B2 - Travel control device - Google Patents

Description

  The present invention provides means for detecting an actual speed related quantity of the own vehicle, means for setting a target speed related quantity of the own vehicle, and braking force generating means for the own vehicle so that the actual speed related quantity becomes the target speed related quantity. And a travel control device comprising:

Conventionally, in switching between a first operation mode that decelerates with an engine brake or the like and a second operation mode that performs deceleration control with a hydraulic brake or the like, it is based on frequent switching of operation modes using hysteresis that changes with time and two threshold values. A technique for preventing blinking of a brake lamp and shock to a driver is known (for example, see Patent Document 1).
JP 2003-531051 A

  However, the above-described conventional technique has a problem in that, when the operation mode is switched, an uncomfortable feeling due to a change in deceleration received by the driver when switching from engine braking to hydraulic braking is not considered.

  The present invention has been made in view of such problems, and an object of the present invention is to reduce a sense of incongruity due to a change in deceleration during brake operation.

The travel control device according to the first aspect of the present invention is configured to brake the host vehicle so that the actual acceleration of the host vehicle becomes a braking target acceleration when the first target acceleration of the host vehicle becomes a value equal to or less than a threshold value. When the control means and the first target acceleration are equal to or less than the threshold, the mixing ratio of the first target acceleration increases as the difference between the first target acceleration and the threshold increases. As described above, means for calculating the braking target acceleration by performing an operation of mixing the first target acceleration and the second target acceleration having a smaller degree of deceleration than the first target acceleration, It is characterized by comprising.

The travel control device according to a second aspect of the present invention is the travel control device according to the first aspect, wherein the means for calculating the braking target acceleration further raises the first target acceleration by the threshold value. The second target acceleration is calculated.

The travel control device according to a third aspect of the present invention is the travel control device according to the first aspect, wherein the means for calculating the braking target acceleration is the time when the first target acceleration becomes a value equal to or less than the threshold value. When the actual acceleration is smaller than 0, the second target acceleration is further calculated based on the actual acceleration at the time point.

The travel control device according to a fourth aspect of the present invention is the travel control device according to the third aspect, wherein the means for calculating the braking target acceleration calculates the first target acceleration from the actual acceleration at the time point. The second target acceleration is calculated by raising the amount by subtracting the target acceleration.

The travel control device according to a fifth aspect of the present invention is the travel control device according to any one of the first to fourth aspects, wherein the minimum value of the mixing ratio is 0% and the maximum value is 100%. To do.

The travel control device according to a sixth aspect of the present invention is the travel control device according to the third aspect, wherein the means for calculating the braking target acceleration has a calculation result of the second target acceleration that is greater than the actual acceleration at the time. The second target acceleration is calculated so as to be a large value.

A travel control device according to a seventh invention is the travel control device according to any one of the first to sixth inventions, wherein the first target acceleration is calculated based on a target acceleration candidate corresponding to a travel situation of the host vehicle. It is characterized by further comprising means for performing.

A travel control device according to an eighth invention is the travel control device according to the seventh invention, wherein the target acceleration candidate has an acceleration required to travel while maintaining a predetermined distance from a preceding vehicle, and a constant vehicle speed. It includes the acceleration necessary to travel while maintaining, and the acceleration necessary to enter the corner at a speed at which unacceptable lateral acceleration does not occur when turning.

A travel control device according to a ninth aspect of the present invention is the travel control device according to any one of the first to eighth aspects, wherein the means for calculating the braking target acceleration further includes a travel resistance applied to the host vehicle or the host vehicle. The threshold value is changed according to a change in the gradient of the road on which the vehicle travels.

As described above, according to the travel control device of the first invention, it is possible to effectively mitigate changes in vehicle body acceleration. As a result, it is possible to reduce a sense of incongruity due to a change in deceleration when the brake is operated.

According to the travel control device of the second invention , the second target acceleration can be set to zero when the first target acceleration matches the threshold value.

According to the travel control device of the third invention, it is possible to realize a smoother acceleration change.

According to the travel control device of the fourth aspect of the present invention, the actual acceleration of the host vehicle at the time when the first target acceleration becomes a value equal to or smaller than the threshold value can be set as the second target acceleration.

According to the travel control device of the fifth invention, the braking target acceleration can have a value in the range of the second target acceleration to the first target acceleration.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  First, an example of a vehicle on which the traveling control device of the present invention is mounted will be described with reference to FIG.

  This vehicle includes wheels 100 on the front, rear, left and right respectively. In FIG. 1, “FL” indicates a left front wheel, “FR” indicates a right front wheel, “RL” indicates a left rear wheel, and “RR” indicates a left rear wheel.

  This vehicle includes an engine 140 as a power source. The drive source is not limited to the engine, and may be only an electric motor or a combination of the engine and the electric motor. The power source of the electric motor may be a secondary battery or a fuel cell.

  The driving state of engine 140 is electrically controlled according to the amount of operation of accelerator pedal 200 (an example of an operating member operated by the driver to control the longitudinal movement of the vehicle) by the driver. The operating state of the engine 140 is also automatically controlled as necessary regardless of the operation of the accelerator pedal 200 by the driver.

  Such electrical control of the engine 140 is, for example, electrically controlling the opening degree of a throttle valve (that is, the throttle opening degree) disposed in the intake manifold of the engine 140, although not shown, This can be realized by electrically controlling the amount of fuel injected into the 140 combustion chambers and electrically controlling the phase of the intake camshaft for adjusting the valve opening / closing timing.

  This vehicle is a rear wheel drive type in which left and right front wheels are rolling wheels and left and right rear wheels are drive wheels. Therefore, the output shaft of engine 140 is connected to each rear wheel via torque converter 220, transmission 240, propeller shaft 260 and differential 280, and drive shaft 300 that rotates with each rear wheel in that order. The torque converter 220, the transmission 240, the propeller shaft 260, and the differential 280 are power transmission elements common to the left and right rear wheels. The vehicle does not need to be a rear wheel drive type. For example, even if the vehicle is a front wheel drive type in which the left and right front wheels are drive wheels and the left and right rear wheels are rolling wheels, the vehicle is a 4WD type in which all wheels are drive wheels. There may be.

  The transmission 240 includes an automatic transmission (not shown). This automatic transmission electrically controls the gear ratio when shifting the rotational speed of engine 140 to the rotational speed of the output shaft of transmission 240. The automatic transmission may be a stepped transmission or a continuously variable transmission (CVT).

  Each wheel 100 is provided with a brake 560 that is actuated to suppress its rotation. The brake 560 is, for example, a disc brake type that generates a braking force by pressing a friction material (pad) on both surfaces of a disc (disk) that rotates integrally with the wheel 100 by the hydraulic pressure of the actuator, or a rotation that rotates integrally with the wheel 100. Any type of brake may be used including a drum brake type in which a friction member (shoe) is pressed against the inner surface of the member (drum) by hydraulic pressure of an actuator to generate a braking force.

  Each brake 560 is electrically operated according to an operation amount of a brake pedal 580 (an example of an operation member operated by the driver to control the longitudinal movement of the vehicle) by a driver by an actuator provided for each brake 560. In addition, it is automatically controlled for each wheel 100 as needed.

  As shown in FIG. 1, the travel control device 1000 is mounted on a vehicle in a state where it is electrically connected to the various actuators described above. The travel control device 1000 is a control device that operates using an auxiliary battery (not shown) as a power source, and mainly controls braking / driving force in automatic travel control (ACC: adaptive cruise control) as described in detail below.

  FIG. 2 is a system configuration diagram showing an embodiment of the travel control apparatus 1000 of the present embodiment. The travel control apparatus 1000 is embodied by an ECU (Electronic Control Unit). The ECU is configured by a microcomputer, and includes, for example, a ROM for storing a control program, a readable / writable RAM for storing calculation results, a timer, a counter, an input interface, an output interface, and the like.

  The travel control apparatus 1000 is roughly classified into functional groups, and includes a target acceleration calculation unit 10 and an actuator selection unit 20. An engine control unit 30 and a brake control unit 40 are connected to the actuator selection unit 20.

  The target acceleration calculation unit 10 includes a recognition unit 12, a target acceleration candidate calculation unit 14, an arbitration unit 16, and a change rate limiting unit 18.

  The recognition unit 12 acquires preceding vehicle information from a radar sensor and / or an image sensor 50 mounted on the vehicle. The radar radiates a detection wave, and receives the detection wave reflected by the preceding vehicle in the detection zone of the radar sensor among the radiated detection waves, so that the distance from the own vehicle of the preceding vehicle and the preceding vehicle A relative direction with respect to the own vehicle is generated as preceding vehicle information. For example, the radar sensor scans the front of the vehicle by reciprocatingly swinging the detection wave beam in a direction intersecting the traveling direction within a set angle range, thereby covering the entire fan-shaped detection zone. The detection wave emitted by the radar may be a light wave (for example, a laser wave), a radio wave (for example, a millimeter wave), or a sound wave (for example, an ultrasonic wave). By the way, all vehicles generally have a pair of reflectors separated from each other on the rear surface. By using the reflected waves from the pair of reflectors in each vehicle, the radar can distinguish each vehicle from other vehicles even in the detection zone.

  The image sensor is, for example, a sensor using a CCD (stereo) camera (hereinafter referred to as “front monitoring camera”). The front monitoring camera is mounted so as to capture a landscape in front of the vehicle, and is fixed, for example, near a room mirror in the vehicle interior. The image sensor, based on the image data of the preceding vehicle captured by the front monitoring camera, uses, for example, the principle of triangulation, to calculate the distance from the own vehicle of the preceding vehicle and the relative direction of the preceding vehicle to the own vehicle. Generated as preceding vehicle information.

  The target acceleration candidate calculation unit 14 calculates three target accelerations as target acceleration candidates, that is, a tracking target acceleration, a constant speed target acceleration, and a corner acceleration prohibition target acceleration. The target acceleration for tracking is calculated as the acceleration necessary for traveling while maintaining a predetermined distance or speed relationship with respect to the preceding vehicle based on the preceding vehicle information. The target acceleration for constant speed is calculated as an acceleration necessary for traveling while maintaining a predetermined constant vehicle speed. The target acceleration for corner acceleration prohibition is the acceleration (mainly deceleration) required to enter the corner approaching the front of the vehicle at a predetermined target speed (a speed at which unacceptable lateral acceleration does not occur when turning). Calculated.

  In the description of this embodiment, the direction of acceleration is positive on the front side in the vehicle traveling direction. Therefore, positive acceleration corresponds to the acceleration direction of the vehicle, and negative acceleration corresponds to the deceleration direction of the vehicle.

  In the arbitration unit 16, these target acceleration candidates are arbitrated according to predetermined arbitration conditions, and one appropriate target acceleration is determined from these mediation candidates. The target acceleration thus determined is subjected to processing for limiting the rate of change by the rate-of-change limiting unit 18 (for example, upper limit guard processing), and is output to the actuator selecting unit 20.

  The present invention is characterized by the final determination mode of the target acceleration in the actuator selection unit 20 described in detail below, and includes a method for calculating the target acceleration for tracking, the target acceleration for constant speed, and the target acceleration for corner acceleration prohibition, These arbitration methods and the like may be any other appropriate method.

The actuator selection unit 20 determines the target acceleration G _BR for brake instruction based on the target acceleration (hereinafter referred to as “target acceleration G1”) input from the target acceleration calculation unit 10 as described above.

FIG. 3 is a flowchart of the brake instruction target acceleration G _BR determination process realized by the actuator selection unit 20.

In step 1000, the actuator selection unit 20 monitors the target acceleration G1 input from the target acceleration calculation unit 10 every predetermined period as described above, and the target acceleration G1 is a predetermined threshold value G _thr for determining whether the brake 560 can be operated. It is determined whether or not (<0). If it does not fall below the predetermined threshold value G _thr , it is determined that the operation of the brake 560 is not necessary (step 1001), and the process ends as it is (in this case, the brake instruction target acceleration G _BR = 0). On the other hand, when the target acceleration G1 falls below the predetermined threshold _Gthr , the process proceeds to step 1100.

In step 1100, the actuator selection unit 20 calculates the raised target acceleration G2 based on the target acceleration G1. The raised target acceleration G2 is obtained by raising the target acceleration G1 by a predetermined threshold G _thr , and specifically, (lifted target acceleration G2) = (target acceleration G1) − (predetermined threshold G _thr ). Accordingly, when the target acceleration G1 coincides with the predetermined threshold G _thr , the raising target acceleration G2 is zero.

Subsequently, in step 1200, the actuator selection unit 20 calculates a mixture ratio γ (0 ≦ γ ≦ 1) between the target acceleration G1 and the raised target acceleration G2 used when calculating the brake instruction target acceleration _GBR . A method of calculating the mixture ratio γ will be described later with reference to FIG.

Subsequently, in step 1300, the actuator selection unit 20 calculates the target acceleration G _BR for brake instruction using G _BR = γ · G1 + (1−γ) · G2 using the calculated mixture ratio γ.

Incidentally, once the target acceleration G1 is below a predetermined threshold value _{G thr,} thereafter, the target acceleration G1 exceeds the predetermined threshold value _{G thr,} until operation of the brake 560 is terminated, the periodic processing of step 1100, 1200, 1300 is It is repeated (for example, every calculation cycle of the target acceleration G1).

The actuator selection unit 20 sends the brake instruction target acceleration _GBR calculated in this way to the brake control unit 40 together with the target acceleration G1 for each calculation cycle. In addition, the actuator selection unit 20 sends the target acceleration G1 input from the target acceleration calculation unit 10 to the engine control unit 30 every calculation cycle as it is as “engine instruction target acceleration”. It should be noted that the brake instruction target acceleration G _BR and the engine instruction target acceleration calculated based on the target acceleration G1 obtained in the same cycle are in synchronization with each other, and the engine control unit 30 and the brake control, respectively. Sent to the unit 40.

The engine control unit 30 determines the target engine torque (finally the target throttle opening) and the target gear stage in accordance with the target acceleration G1 commanded from the actuator selection unit 20 as described above, and the engine 140 and the transmission 240 Integrated actuator control. When the target acceleration G1 commanded from the actuator selection unit 20 is equal to or less than the predetermined threshold value G _thr (that is, when a braking force greater than the maximum braking force that can be generated by the engine brake is commanded), the engine control unit 30 The throttle valve of the engine 140 is maintained in a fully closed state while shifting the transmission gear ratio of the transmission 240 in a decreasing direction.

Further, in the case of a vehicle including an electric motor (motor generator) as a drive source, the engine control unit 30 generates an electric braking force according to the negative target acceleration G1 commanded from the actuator selection unit 20. To control. Similarly, when the target acceleration G1 commanded from the actuator selection unit 20 is equal to or less than a predetermined threshold _Gthr (that is, the braking force greater than the maximum braking force that can be generated by regenerative braking is commanded). The maximum braking force that can be generated by regenerative braking is maintained. Whether or not the regenerative braking force is generated and / or the magnitude thereof may be determined and corrected according to other factors such as the state of the battery (secondary battery or fuel cell).

The brake control unit 40 controls the actuators of the brakes 560 so that the brake instruction target acceleration _GBR is realized when the target acceleration G1 commanded from the actuator selection unit 20 is equal to or less than the predetermined threshold _Gthr .

As described above, in this embodiment, the target acceleration G1 commanded from the actuator selection unit 20 is negative, but when the target acceleration G1 is not equal to or less than the predetermined threshold G _thr , the entire braking force is provided by the engine brake (or regenerative braking). _Only when the target acceleration G1 becomes equal to or less than the predetermined threshold value _Gthr , the brake 560 is activated (a hydraulic braking force is generated by a so-called mechanical brake). As a result, the brake 560 can be actuated as little as possible, and frequent lighting of the brake lamp and wear of the brake pads can be prevented.

  Here, with reference to FIG. 4, the characteristic configuration and operation of the present embodiment will be described. FIG. 4A is a graph showing how the target acceleration G1 changes in a traveling scene where deceleration is required, with the horizontal axis representing time and the vertical axis representing acceleration.

Here, as shown in FIG. 4 (A), under the situation where the steady running state is formed by the automatic running control, the inter-vehicle distance with the preceding vehicle starts to shorten near time t0, and deceleration is necessary. Thereafter, a driving scene is assumed in which the inter-vehicle distance is further shortened and the maximum deceleration G _MAX is required near time t2.

In such a traveling scene, conventionally, according to control, the inter-vehicle distance from the preceding vehicle starts to decrease around time t0, and the target acceleration G1 becomes smaller and the target acceleration G1 becomes a predetermined value as shown in FIG. At time t1 when the value is equal to or less than the threshold value G _{thr, the} brake 560 is operated to generate the target acceleration G1 (a hydraulic braking force corresponding to the target acceleration G1 is generated). At this time, if the change in the actual vehicle body acceleration (actual acceleration) can be made to completely follow the change in the target acceleration G1, the realized acceleration is theoretically equal to the target acceleration G1, and the brake 560 is activated. There is no change in the vehicle acceleration that can be felt by the occupant, but in reality, there is a slight deviation between the two, which causes discomfort when the brake 560 is activated ( Shock) occurs.

FIG. 4B is a graph showing a change mode of the target acceleration G _BR according to the present embodiment in the same traveling scene, where the horizontal axis represents time and the vertical axis represents acceleration.

FIG. 4B shows the raising target acceleration G2 calculated in step 1100. As shown in FIG. 4B, the raised target acceleration G2 is a curve obtained by shifting the curve representing the trajectory of the target acceleration G1 by a predetermined threshold G _thr as shown in FIG. 4B. Accordingly, at the time t1 when the target acceleration G1 becomes equal to or less than the predetermined threshold value _Gthr , the raising target acceleration G2 becomes zero.

In the present embodiment, as described above in connection with the processing of step 1300, the brake instruction target acceleration after the time point t1 when the target acceleration G1 becomes equal to or less than the predetermined threshold G _thr is not the target acceleration G1 but the target acceleration. G _BR (= γ · G1 + (1−γ) · G2) is employed. That is, the target acceleration G _BR calculated by mixing the target acceleration G1 and the raising target acceleration G2 with an appropriate mixing ratio γ (0 ≦ γ ≦ 1) is employed as the brake instruction target acceleration.

In the present embodiment, the mixture ratio γ is determined according to which position the target acceleration G1 is between the predetermined threshold G _thr and the maximum deceleration G _MAX . That is, the closer the target acceleration G1 is to the predetermined threshold G _thr (for example, near the time point t1), the smaller the mixture ratio γ of the target acceleration G1 becomes, and as a result, the mixture ratio (1−γ ) Is a large value close to 1. On the other hand, the closer the target acceleration G1 is to the maximum deceleration G _MAX (for example, around the time point t2), the larger the mixture ratio γ of the target acceleration G1 becomes, and as a result, the mixture ratio (1- γ) is set to a small value close to 0.

When this is expressed by a mathematical expression, the absolute value of the difference between the maximum deceleration G _MAX (fixed value) and the threshold G _thr (fixed value) is α (see FIG. 4B), and the maximum deceleration G _MAX (fixed value). ) And the target acceleration G1 is β (see FIG. 4B), the mixture ratio γ of the target acceleration G1 is γ = 1−β / α. As described above, in this embodiment, the mixture ratio γ calculated in step 1200 is not a fixed value, but changes with the change in the target acceleration G1.

In this case, as shown in FIG. 4B, the target acceleration G _BR matches the raised target acceleration G2 at time t1, and matches the target acceleration G1 (= maximum deceleration G _MAX ) at time t2. It changes linearly while taking a value between the raised target acceleration G2 and the target acceleration G1.

Therefore, according to the traveling control according to the present embodiment, similarly, the inter-vehicle distance from the preceding vehicle starts to decrease near time t0, and the target acceleration G1 becomes smaller and smaller as shown in FIG. 4B. The brake 560 is actuated (hydraulic braking force is generated) at a time t1 when becomes less than or equal to the predetermined threshold G _thr . At this time, the hydraulic braking force generated by the brake 560 is not intended to correspond to the target acceleration G1 matching at time t1 a predetermined threshold value G _thr, the target acceleration G _BR matching raised target acceleration G2 is substantially zero It will be corresponding. Therefore, the hydraulic braking force generated by the brake 560 starts from zero and gradually increases to the maximum braking force from time t1 to time t2 when the maximum deceleration G _MAX is required.

Therefore, according to the present embodiment, the target acceleration G1 becomes equal to or less than the predetermined threshold value G _{thr in a} situation where the change in the actual vehicle body acceleration (actual acceleration) does not completely follow the change in the target acceleration G1. Even when the operation is performed, the change in the vehicle body acceleration that can be felt as described above is effectively mitigated, and the uncomfortable feeling (shock) when the brake 560 is operated can be effectively reduced.

Further, in this embodiment, the brake 560 is operated at the time t1 when the target acceleration G1 becomes equal to or less than the predetermined threshold value _Gthr , so that the brake 560 is compared with a configuration in which the target acceleration G1 is smoothed by a filter. It is possible to eliminate the response delay of the operation. Maximum Also, at time t2 the target acceleration G1 is equal to the maximum deceleration G _MAX, since the target acceleration G _BR corresponding to the maximum deceleration G _MAX is commanded, that are required to ensure safe travel control The deceleration G _MAX can be generated without a response delay.

Next, another preferred embodiment of the present invention will be described with reference to FIGS. This embodiment differs from the above-described embodiment only in the method for determining the brake instruction target acceleration G _BR , and other configurations (for example, the method for realizing the brake instruction target acceleration G _BR ) are different from those in the above-described embodiment. The description of the same part is omitted.

FIG. 5 is a flowchart of the brake instruction target acceleration G _BR determination process realized by the actuator selection unit 20 of this embodiment. Note that the same processing in the flowchart of FIG. 3 used in the above-described embodiment is denoted by the same step number and description thereof is omitted.

In step 1010 following step 1000, the actuator selection unit 20 calculates the actual acceleration (actual vehicle acceleration) at the time when the target acceleration G1 becomes equal to or less than the predetermined threshold G _thr, and determines whether the actual acceleration is greater than zero. to decide. The actual acceleration may be derived based on an output signal from a wheel speed sensor provided on each wheel 100 (for example, it may be derived as a differential value of speed).

When the actual acceleration is greater than or equal to zero, the same processing as in the above-described embodiment, that is, the same processing as in steps 1100, 1200, and 1300 in FIG. 3 is performed, and the target acceleration G _BR ( = Γ · G1 + (1−γ) · G2) is determined. Incidentally, when entering the routine of step 1100 side, thereafter, the target acceleration G1 exceeds the predetermined threshold value _{G thr,} until operation of the brake 560 is completed, the process of step 1100, 1200, 1300 are periodically repeated.

  On the other hand, if the actual acceleration is less than zero, the process proceeds to step 1110.

In step 1110, the actuator selector 20, the actual acceleration of the time the target acceleration G1 is equal to or less than a predetermined threshold value G _thr (hereinafter referred to as "actual acceleration Greal") based on, for calculating the raised target acceleration G2. The raised target acceleration G2 is obtained by raising the target acceleration G1 by the amount obtained by subtracting the target acceleration G1 from the actual acceleration Greal. Specifically, (raised target acceleration G2) = (actual acceleration Greal).

Subsequently, the actuator selector 20, as step 1210, the mixing ratio γ (0 ≦ γ ≦ the target acceleration G1 and the additional target acceleration G2 used to calculate the target acceleration G _BR brake instruction (= actual acceleration Greal) 1) is calculated. The calculation method of the mixing ratio γ is the same as in the above-described embodiment.

Subsequently, the actuator selection unit 20 calculates a brake instruction target acceleration G _BR in step 1310 using G _BR = γ · G1 + (1−γ) · G2 using the calculated mixture ratio γ.

Incidentally, when entering the routine of step 1110 side, thereafter, the target acceleration G1 exceeds the predetermined threshold value _{G thr,} until operation of the brake 560 is completed, the process of step 1110,1210,1310 are periodically repeated.

FIG. 6 is a diagram corresponding to FIG. 4A, and is a graph showing a change mode of the target acceleration G _BR according to the present embodiment in the same traveling scene as described above. The horizontal axis represents time, and the vertical axis represents acceleration. is there. FIG. _6A is a graph showing how the target acceleration G _BR changes when the routine on the step 1100 side in FIG. 5 is entered, and FIG. 6B shows the case where the routine on the step 1110 side is entered. It is a graph which shows the change mode of target acceleration _GBR . However, in this example, as shown in FIGS. 6 (A) and 6 (B), the actual acceleration changes in the respective driving scenes shown in FIGS. 6 (A) and 6 (B). To do.

  FIGS. 6 (A) and 6 (B) show the raising target acceleration G2 calculated in steps 1100 and 1110, respectively.

In the case of FIG. 6A, as in FIG. 5B, the raised target acceleration G2 is apparent from the above-described calculation method, but the locus curve of the target acceleration G1 is shifted in parallel by a predetermined threshold value G _thr . It becomes a curve. Accordingly, at the time t1 when the target acceleration G1 becomes equal to or less than the predetermined threshold value _Gthr , the raising target acceleration G2 becomes zero.

  In the case of FIG. 6B, the raising target acceleration G2 is apparent from the above-described calculation method, but the target acceleration G1 is shifted in parallel by shifting the locus curve of the target acceleration G1 by “the amount obtained by subtracting the target acceleration G1 from the actual acceleration Greal”. It becomes a curve.

In this embodiment, by considering the actual acceleration Greal at which the target acceleration G1 as described above is equal to or less than a predetermined threshold value G _thr, in addition to the same effect as the above embodiment, further, the actual acceleration Greal negative In this case, a smoother acceleration change can be realized, and a larger total braking force can be secured until the maximum deceleration G _MAX is reached. That is, in the present embodiment, when the actual acceleration Greal is negative, an appropriate initial hydraulic braking force (not zero) according to the actual acceleration Greal can be generated at the time t1 when the brake 560 starts operation. Thus, it is possible to increase the total generated braking force until reaching the maximum deceleration G _MAX while alleviating the shock at the start of operation of the brake 560.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

For example, in the above-described embodiment, the brake instruction target acceleration G _BR (mixing ratio γ) is between the target acceleration G1 and the raised target acceleration G2, with the target acceleration G1 and the predetermined threshold G _thr or the maximum deceleration G _MAX . However, the present invention is not limited to such a configuration and can be changed nonlinearly.

  Further, in the above-described embodiment, the raising target acceleration G2 is set by shifting (translating) the target acceleration G1 by a certain predetermined value, but the present invention is not limited to this. For example, the target acceleration with a degree of deceleration smaller than the target acceleration G1 is shifted without being based on the target acceleration G1 (independent of the target acceleration G1). You may set as the raising target acceleration G2.

In the above-described embodiment, when the target acceleration G1 substantially coincides with the predetermined threshold _Gthr , the mixture ratio γ of the target acceleration G1 is set to 0. As a result, the mixture ratio of the raised target acceleration G2 is set to 1. However, the present invention is not limited to this. For example, when the raising target acceleration G2 is set so that the raising target acceleration G2 is positive and the target acceleration G1 substantially matches the predetermined threshold _Gthr , the target acceleration G1 and the raising target acceleration G2 are not 1: 0. The final target acceleration (brake instruction target acceleration G _BR ) calculated as a result of mixing at the mixing ratio may be substantially zero.

Similarly, in the above-described embodiment, when the target acceleration G1 is substantially equal to a predetermined threshold value G _thr, actual acceleration Greal substantially the same raising target acceleration G2 is the vehicle, the mixing ratio of 1: 0 and set to be However, the present invention is not limited to this. For example, the final target acceleration calculated as a result of setting the raised target acceleration G2 to a value larger than the actual acceleration Greal and mixing the target acceleration G1 and the raised target acceleration G2 with a mixture ratio other than 1: 0. (Brake instruction target acceleration G _BR ) may substantially match the actual acceleration Greal of the vehicle.

In the above-described embodiment, the predetermined threshold value G _thr is a fixed value corresponding to the maximum braking force that can be generated by a braking force generation unit (for example, engine brake or regenerative brake) other than the brake 560. May be changed as a parameter. For example, considering that the braking force acting on the entire vehicle changes mainly depending on the running resistance that depends on the vehicle speed and the change in the road gradient, the variable threshold is added to the predetermined threshold G _thr as a parameter. May be given.

  In the above-described embodiments, the acceleration of the vehicle is used as a physical quantity representing the target value. Target engine torque or the like) may alternatively be used as the target value. In addition, the speed of the vehicle may be employed as a physical quantity representing the target value. Comparing the actual speed and the target speed, if the target speed is greater than the actual speed, the target speed will be the value on the acceleration side. Conversely, if the target speed is smaller than the actual speed, the target speed will be decelerated. When the target speed is equal to the actual speed, the target speed is zero acceleration / deceleration.

  In the above-described embodiment, it is assumed that the automatic traveling control is realized by feedback control based on vehicle speed information obtained from the wheel speed sensor so as to realize the target acceleration G1, but the target acceleration calculating unit 10 It is also possible to realize by open loop control by adding a running resistance, a road gradient and the like to the target acceleration determined by.

It is a top view of a vehicle. 1 is a system configuration diagram illustrating an embodiment of a travel control device according to the present embodiment. 6 is a flowchart of a determination process of a brake instruction target acceleration _GBR realized by the actuator selection unit 20 according to the first embodiment. FIG. 4A is a graph showing how the target acceleration G1 changes in a certain driving scene that requires deceleration, and FIG. 4B shows how the target acceleration G _BR changes in the driving scene according to this embodiment. It is a graph which shows. It is a flowchart of the determination process of the target acceleration _GBR for brake instructions implement | achieved by the actuator selection part 20 of Example 2. FIG. FIG. _6A is a graph showing how the target acceleration G _BR changes when the routine on the step 1100 side in FIG. 5 is entered, and FIG. 6B shows the case where the routine on the step 1110 side is entered. It is a graph which shows the change mode of target acceleration _GBR .

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Target acceleration calculating part 12 Recognition part 14 Target acceleration candidate calculating part 16 Arbitration part 18 Change rate restriction | limiting part 20 Actuator selection part 30 Engine control part 40 Brake control part 50 Radar sensor and / or image sensor 100 Wheel 140 Engine 200 Accelerator pedal 220 Torque converter 240 Transmission 260 Propeller shaft 280 Differential 300 Drive shaft 560 Brake 580 Brake pedal

Claims (9)

Means for controlling the brake of the host vehicle so that the actual acceleration of the host vehicle becomes a braking target acceleration when the first target acceleration of the host vehicle becomes a value equal to or less than a threshold;
When the first target acceleration is equal to or less than the threshold value, the first target acceleration and the threshold value are increased so that the mixing ratio of the first target acceleration increases as the difference between the first target acceleration and the threshold value increases. And a means for calculating the braking target acceleration by performing a calculation of mixing one target acceleration and a second target acceleration that is less decelerated than the first target acceleration . The travel control device according to claim 1, wherein the means for calculating the braking target acceleration further calculates the second target acceleration by raising the first target acceleration by the threshold value . The means for calculating the braking target acceleration is further configured to calculate the braking target acceleration based on the actual acceleration at the time when the actual acceleration at the time when the first target acceleration becomes a value equal to or less than the threshold. The travel control device according to claim 1 , wherein a target acceleration of 2 is calculated . The means for calculating the braking target acceleration calculates the second target acceleration by raising the first target acceleration by an amount obtained by subtracting the first target acceleration from the actual acceleration at the time point. Item 4. The travel control device according to item 3 . The travel control device according to claim 1 , wherein the minimum value of the mixing ratio is 0% and the maximum value is 100% . The means for calculating the braking target acceleration calculates the second target acceleration so that a calculation result of the second target acceleration is larger than the actual acceleration at the time point . Travel control device. The travel control apparatus according to any one of claims 1 to 6, further comprising means for calculating the first target acceleration based on a target acceleration candidate corresponding to a traveling state of the host vehicle . The target acceleration candidates are the acceleration required to travel while maintaining a predetermined distance from the preceding vehicle, the acceleration necessary to travel while maintaining a constant vehicle speed, and the speed at which unacceptable lateral acceleration does not occur when turning The travel control device according to claim 7, wherein the travel control device includes an acceleration required to enter the corner . The travel according to any one of claims 1 to 8, wherein the means for calculating the braking target acceleration further changes the threshold according to a change in a running resistance applied to the host vehicle or a gradient of a road on which the host vehicle runs. Control device.

Images