JP5546106B2 - Vehicle motion control device - Google Patents

Description

  The present invention relates to a vehicle motion control device, and more particularly to a device that performs automatic deceleration (deceleration control) of a vehicle when the vehicle passes a curve in front of the vehicle on a running road.

  Conventionally, there is one described in Patent Document 1 as one of such devices. In the device described in Patent Document 1, in order to set the vehicle speed to an appropriate approach vehicle speed when the vehicle enters the curve, the deceleration distance that requires deceleration when entering the curve, and the curve start point from the current position of the vehicle. The remaining distance until is acquired. Then, the deceleration control is started when the remaining distance that is decreasing reaches the deceleration distance, and the deceleration control is terminated when the remaining distance becomes zero and the vehicle passes the curve start point.

Moreover, there exists what was described in patent document 2 as one of this kind of apparatuses. In the device described in Patent Document 2, in order to suppress the driver from feeling uncomfortable such as a feeling of acceleration failure near the curve end point due to the deceleration control being performed during the curve travel, When it is determined that the vehicle is traveling ahead, the amount of deceleration control is decreased to reduce the degree of deceleration of the vehicle. In other words, the deceleration control is not finished until the vehicle passes the curve end point.
Japanese Patent No. 3385812 JP-A-2005-170152

  As shown in FIG. 16, in a general road, one curve is in order from a curve start point (curve entrance) to a curve end point (curve exit), an approach relaxation curve section, a constant curvature radius section, and an exit. It consists of relaxation curve sections. The relaxation curve is composed of a clothoid curve, for example. The relaxation curve section is provided so that the driver can smoothly turn the steering wheel and then gradually turn it back without requiring the driver to operate the steering wheel suddenly. It is for doing so.

  Assume that the approach relaxation curve section is long. In this case, when the deceleration control is performed so that the deceleration ends at the curve start point as in the device described in Patent Document 1, the start / end of the deceleration control is earlier than the driver's intention, and the driver You may feel uncomfortable.

  In addition, when the driver decelerates the vehicle even though the driver is trying to accelerate the vehicle, the driver may feel uncomfortable when the vehicle desires to accelerate the vehicle despite the driver's desire. Occurs when unable to do so. In particular, the driver does not drive while looking at the immediate vicinity in front of the host vehicle, but operates while predicting the vehicle state at that point while looking at a point ahead of the host vehicle. Therefore, when the deceleration control is not finished until the vehicle passes the curve end point as in the device described in Patent Document 2, the driver may still feel uncomfortable.

  The present invention has been made to cope with such a problem, and an object of the present invention is to provide a vehicle motion control device that can achieve deceleration control with less discomfort given to the driver when passing a curve in front of the vehicle ( It is to provide a deceleration control device.

  The vehicle motion control apparatus according to the present invention includes vehicle speed acquisition means, shape acquisition means, position acquisition means, determination means, calculation means, and deceleration control means. Hereinafter, these means will be described in order. Hereinafter, in the present specification, a side closer to the vehicle and a side farther from a certain point may be referred to as “front side” and “back side”, respectively. Further, “passing the curve start point” may be referred to as “entering the curve”, and “passing the curve end point” may be referred to as “exiting the curve”.

  The vehicle speed acquisition means acquires the vehicle speed of the vehicle using one of well-known methods such as a method using the output of the wheel speed sensor.

  The shape acquisition means acquires the shape of a curve in front of the vehicle on the road on which the vehicle is traveling. The shape of the curve can be acquired from road information stored in a navigation device mounted on the vehicle, for example.

  The position acquisition means acquires a relative position of the vehicle with respect to the curve. This relative position can be acquired from, for example, road information stored in a navigation device mounted on the vehicle and a vehicle position obtained from a global positioning system mounted on the navigation device.

  The determining means determines, based on the shape of the curve, a reference point that is a point in the middle of the curve and an appropriate vehicle speed when the vehicle passes through the reference point. “In the middle of a curve” is a point between a curve start point and a curve end point for one curve.

  The reference point may be determined, for example, as an end point of a relaxation curve section (start point of a constant curvature radius section) on the approach side of the curve, or a point closer to the vehicle with respect to the end point. Further, the appropriate vehicle speed can be set to a larger value (a value at which the vehicle can properly turn the curve) as the minimum curvature radius in the curve is larger, for example.

  The calculating means decelerates the vehicle on the road closer to the vehicle from the reference point (when the vehicle enters the curve) based on the reference point and the appropriate vehicle speed. In this case, a target vehicle speed characteristic that is a target of the vehicle speed reduction characteristic with respect to the position on the road is calculated.

  The target vehicle speed characteristic is, for example, a characteristic that increases as the vehicle speed becomes the appropriate vehicle speed at the reference point and moves away from the reference point toward the side closer to the vehicle. The target vehicle speed characteristic may be a characteristic in which a deceleration of the vehicle is constant.

  The deceleration control means is a control in which a relationship between the vehicle speed and the position of the vehicle with respect to the reference point obtained from the relative position (that is, a distance between the reference point and the vehicle) is determined based on the target vehicle speed characteristic. Deceleration control for decelerating the vehicle is started when a start condition is satisfied, and the deceleration control is performed when the vehicle speed reaches a predetermined range including the appropriate vehicle speed (when the deceleration control is started). finish.

  The control start condition is satisfied, for example, when the current vehicle speed exceeds the vehicle speed at the “current position of the vehicle with respect to the reference point” in the target vehicle speed characteristic. The predetermined range may be zero. The deceleration control is performed so that the vehicle speed decreases along the target vehicle speed characteristic. For example, the vehicle speed is feedback-controlled so that the deviation between the current vehicle speed and the vehicle speed at the “current position of the vehicle with respect to the reference point” in the target vehicle speed characteristic becomes zero. Alternatively, a target deceleration (relative to a position on the road) is introduced and the deceleration is feedback controlled so that the current deceleration matches the target deceleration (eg, constant). The deceleration of the vehicle can be achieved by, for example, wheel braking, driving source output reduction, transmission downshifting (moving the shift stage to a lower side, increasing the reduction ratio), and the like.

  According to the vehicle motion control apparatus of the present invention, the deceleration control is such that the vehicle speed is reduced to the appropriate vehicle speed at a reference point in the middle of the curve (for example, the end point of the approach relaxation curve section). The target is executed regardless of the driver's acceleration / deceleration operation. In view of the fact that the distance from the curve start point to the reference point may be long (for example, when the approach relaxation curve section is long) or short, the deceleration control may determine whether the vehicle has entered the curve. You can get started though.

  In addition, when the vehicle is decelerated to an appropriate vehicle speed, the deceleration control is terminated regardless of whether the vehicle has left the curve. Therefore, the adjustment of the vehicle speed after the end of the deceleration control is left to the driver. From the above, the deceleration control (especially the start timing and end timing) tends to be in line with the driver's intention according to the shape of the curve, and as a result, the uncomfortable feeling given to the driver by the deceleration control is reduced. be able to.

  In the motion control device according to the present invention, the degree of acceleration of the vehicle is limited during a predetermined time from the end point of the deceleration control or while the vehicle travels a predetermined distance from the end point of the deceleration control. An acceleration restriction control means may be provided.

  According to this, for example, when the driver has already performed an acceleration operation from the stage where deceleration control is being executed, the degree of acceleration slip (rapid acceleration) of the drive wheels that can occur immediately after the end of deceleration control is suppressed. Can do. The vehicle acceleration limit can be achieved, for example, by limiting the throttle valve opening.

  In this case, the predetermined time or the predetermined distance is determined based on a distance of a constant radius of curvature section in the curve. For example, the longer the predetermined radius of curvature section, the longer the predetermined time or the longer the predetermined distance. According to this, when the distance of the constant curvature radius section is short, the acceleration restriction is released relatively early, and when it is long, the acceleration restriction is released relatively late, thereby reducing the uncomfortable feeling given to the driver by the acceleration restriction. be able to.

  By the way, there may be a case where two or more continuous curves such as a so-called S-shaped curve and a composite curve (for example, consisting of an approach relaxation curve section, a constant curvature radius section, and an exit relaxation curve section) continue. Alternatively, there is a case where there is a straight section between two curves, but this straight section is very short. In such a case, the shape acquisition unit may recognize two or more curves in front of the vehicle and acquire the shapes of the two or more curves.

  In this case, in the motion control apparatus according to the present invention, the determination means is configured to determine the reference point and the appropriate vehicle speed for each curve, and the calculation means corresponds to each curve. And determining a characteristic corresponding to the target vehicle speed characteristic based on the reference point and the appropriate vehicle speed, and among the control start conditions determined based on each of the two or more characteristics It is preferable that a characteristic corresponding to a condition that can be satisfied earliest is adopted as the target vehicle speed characteristic used by the deceleration control unit.

  According to this, deceleration control can be executed based on the curve that requires the earliest deceleration among the two or more curves.

  In the motion control apparatus according to the present invention, the target vehicle speed characteristic is a characteristic that the deceleration of the vehicle increases in the first half of the deceleration control and / or the deceleration in the second half of the deceleration control. May include a characteristic of decreasing.

  According to this, after the deceleration control is started, the vehicle is first decelerated relatively slowly, then the deceleration is gradually increased, and then the deceleration is decreased and the vehicle is decelerated relatively slowly. Deceleration control can be terminated. Therefore, the degree of change in jerk (jerk) felt by the driver can be reduced, and the uncomfortable feeling given to the driver by the deceleration control can be further reduced.

  In this case, as described above, when the target deceleration is used in the deceleration control, the target deceleration has a characteristic that the deceleration increases in the first half of the deceleration control and / or the deceleration control. It is set while corresponding to the position on the road so as to include the characteristic that the deceleration decreases in the second half. After the control start condition is satisfied, the deceleration is feedback-controlled so that the current deceleration matches the target deceleration set in this way.

  Embodiments of a vehicle motion control device (deceleration control device) according to the present invention will be described below with reference to the drawings.

(Constitution)
FIG. 1 shows a schematic configuration of a vehicle equipped with a motion control device (hereinafter referred to as “the present device”) according to an embodiment of the present invention. This device includes an engine EG that is a power source of the vehicle, an automatic transmission TM, a brake actuator BRK, an electronic control unit ECU, and a navigation device NAV.

  The engine EG is, for example, an internal combustion engine. That is, the opening degree of the throttle valve TV is adjusted by the throttle actuator TH according to the operation of the accelerator pedal (acceleration operation member) AP by the driver. An amount of fuel proportional to the amount of intake air adjusted according to the opening of the throttle valve TV is injected by a fuel injection actuator FI (injector). Thereby, the output torque according to the operation of the accelerator pedal AP by the driver can be obtained.

  The automatic transmission TM is a multi-stage automatic transmission having a plurality of shift stages or a continuously variable automatic transmission having no shift stages. The automatic transmission TM has a reduction ratio (the rotational speed of the EG output shaft (= TM input shaft) / the rotational speed of the TM output shaft) depending on the operating state of the engine EG and the position of the shift lever (transmission operation member) SF. Can be automatically changed (without operation of the shift lever SF by the driver).

  The brake actuator BRK has a known configuration including a plurality of solenoid valves, a hydraulic pump, a motor, and the like. The brake actuator BRK supplies the brake pressure (brake hydraulic pressure) according to the operation of the brake pedal (brake operation member) BP by the driver to the wheel cylinder WC ** of the wheel WH ** and controls when not controlled. Sometimes, the braking pressure in the wheel cylinder WC ** can be adjusted for each wheel independently of the operation of the brake pedal BP (and the operation of the accelerator pedal AP).

  Note that “**” at the end of each symbol is a comprehensive notation such as “fl” or “fr” that indicates which wheel each symbol is related to, and “fl” is on the left. The front wheel, “fr” indicates the right front wheel, “rl” indicates the left rear wheel, and “rr” indicates the right rear wheel. For example, the wheel cylinder WC ** comprehensively indicates a left front wheel wheel cylinder WCfl, a right front wheel wheel cylinder WCfr, a left rear wheel wheel cylinder WCrl, and a right rear wheel wheel cylinder WCrr.

  This device consists of a wheel speed sensor WS ** that detects the wheel speed of the wheel WH **, a braking pressure sensor PW ** that detects the braking pressure in the wheel cylinder WC **, and the steering wheel SW (from the neutral position). A) Steering wheel angle sensor SA that detects the rotation angle, Yaw rate sensor YR that detects the yaw rate of the vehicle body, Longitudinal acceleration sensor GX that detects acceleration (deceleration) in the vehicle body longitudinal direction, and Acceleration in the lateral direction of the vehicle body The lateral acceleration sensor GY, the engine rotation speed sensor NE that detects the rotation speed of the output shaft of the engine EG, the acceleration operation amount sensor AS that detects the operation amount of the accelerator pedal AP, and the operation amount of the brake pedal BP. A brake operation amount sensor BS, a shift position sensor HS that detects the position of the shift lever SF, and a throttle valve opening sensor TS that detects the opening of the throttle valve TV are provided.

  The electronic control unit ECU is a microcomputer that electronically controls the powertrain system and the chassis system. The electronic control unit ECU is electrically connected to the various actuators described above, the various sensors described above, and the automatic transmission TM, or can communicate with each other via a network. The electronic control unit ECU is composed of a plurality of control units (ECU1 to ECU3) connected to each other via a communication bus CB.

  ECU1 in the electronic control unit ECU is a wheel brake control unit and controls the brake actuator BRK based on signals from the wheel speed sensor WS **, longitudinal acceleration sensor GX, lateral acceleration sensor GY, yaw rate sensor YR, etc. Thus, braking pressure control (wheel brake control) such as well-known anti-skid control (ABS control), traction control (TCS control), and vehicle stability control (ESC control) is executed.

  The ECU 2 in the electronic control unit ECU is an engine control unit that controls the throttle actuator TH and the fuel injection actuator FI based on signals from the acceleration operation amount sensor AS and the like, thereby controlling the output torque of the engine EG (engine control). Is supposed to run.

  The ECU 3 in the electronic control unit ECU is an automatic transmission control unit, and executes a reduction ratio control (transmission control) by controlling the automatic transmission TM based on a signal from the shift position sensor HS or the like. It has become.

  The navigation device NAV includes a navigation processing device PRC. The navigation processing device PRC includes vehicle position detection means (global positioning system) GPS, yaw rate gyro GYR, input unit INP, storage unit MAP, and display unit (display). ) Electrically connected to MTR. The navigation device NAV is electrically connected to the electronic control unit ECU or can communicate wirelessly.

  The vehicle position detection means GPS can detect the position (latitude, longitude, etc.) of the vehicle by one of the well-known methods using positioning signals from artificial satellites. The yaw rate gyro GYR can detect the angular velocity (yaw rate) of the vehicle body. The input unit INP is configured to input an operation related to the navigation function by the driver. The storage unit MAP stores various information such as map information and road information.

  The navigation processing device PRC comprehensively processes signals from the vehicle position detection means GPS, yaw rate gyro GYR, input unit INP, and storage unit MAP, and displays the processing results (information related to the navigation function) on the display unit MTR. It is supposed to be.

(Curve deceleration control)
Hereinafter, the curve deceleration control executed by the apparatus configured as described above will be described. Curve deceleration control means that when a vehicle is about to enter a curve with a vehicle speed higher than the speed at which the vehicle can properly pass through the curve (that is, when emergency braking is required), the vehicle can properly pass through the curve. This control decelerates the vehicle regardless of the driver's acceleration / deceleration operation (AP / BP operation). Vehicle deceleration is accomplished using at least one of engine EG output reduction, transmission TM downshift, and wheel brakes.

  In curve deceleration control, deceleration starts based on the vehicle speed (vehicle speed) Vx, the shape of the curve in front of the vehicle, and the relative position of the curve and the vehicle (the position of the vehicle with respect to the curve, the distance between the curve and the vehicle). A point is determined, and deceleration is started at this point. And deceleration is complete | finished when the vehicle speed Vx becomes appropriate.

  The curve deceleration control will be described in detail below with reference to the routine shown by the flowchart in FIG. 2 and the diagram showing the relationship between the position of the vehicle on the road and the vehicle speed shown in FIG. The routine shown in FIG. 2 is executed, for example, every predetermined calculation cycle.

  First, in step 205, a process for recognizing a curve ahead of the vehicle is executed. The curve recognition process is performed by at least one of the navigation device NAV and an image recognition device (not shown). For example, the presence of a curve is recognized when the vehicle approaches a predetermined distance from the curve.

  In step 210, it is determined whether or not a curve exists. If the existence of a curve is not recognized, this routine is terminated. On the other hand, when the existence of the curve is recognized (see point (point N) Pcn in FIG. 3), the processing from step 215 onward is executed.

  In step 215, the current vehicle speed Vx is acquired, in step 220, the shape of the curve closest to the front of the vehicle is acquired, and in step 225, the relative position between the curve from which the shape has been acquired and the vehicle is acquired. Such information can be obtained through a network in the vehicle.

  The shape of the curve (curve radius of curvature Rc) can be read from the curve information included in the map information stored in the storage unit MAP. More specifically, the map information stores in advance the positions of the curve start point, curve end point, and the like, and the radius of curvature at each position. Further, the positions of specific points (node points) on the road and the radius of curvature at each position are stored. As shown in FIG. 4, the curvature radius of the curve can be estimated based on an approximate curve that connects these points geometrically and smoothly. This method is described in detail in Japanese Patent No. 3378490.

  The relative position Pc between the curve and the vehicle is acquired by using the vehicle position detecting means GPS of the navigation device NAV and the map information. More specifically, the current vehicle position (latitude, longitude, etc.) is detected on the coordinates fixed to the earth by the vehicle position detection means GPS. Further, after the initial position of the vehicle is determined by the vehicle position detection means GPS, the vehicle position from the initial position is determined based on information obtained from the yaw rate gyro GYR, the acceleration sensors GX and GY, the wheel speed sensor WS **, and the like. The current vehicle position can be estimated by sequentially updating the relative position. On the other hand, the position of the road (longitude, latitude) is stored in the map information. Therefore, the relative position between the curve and the vehicle can be acquired by comparing the current vehicle position with the road position.

  Further, the relative position between the curve and the vehicle, and the shape of the curve (curvature radius of curvature) can also be acquired by using image processing of a CCD camera mounted on the vehicle. More specifically, a white line on the road or a road edge is detected based on an image of a stereo camera mounted on the vehicle. Then, the distance distribution in the entire image is calculated based on the shift amount of the corresponding position in the stereo image and the principle of triangulation, and the distance from the vehicle to the curve (that is, the curve and the vehicle) is calculated based on the calculation result. Relative distance) and the radius of curvature of the curve. This method is described in detail in Japanese Patent No. 3378490.

  In step 230, the appropriate vehicle speed Vq is determined based on the curvature radius of the curve (for example, the minimum curvature radius Rm in the curve) (see FIG. 3). The appropriate vehicle speed Vq is set to a larger value as the minimum radius of curvature Rm is larger, for example, using the table shown in FIG.

  In step 235, the reference point Pcr is determined. The reference point Pcr is a point targeted for achieving the appropriate vehicle speed Vq. The reference point Pcr can be selected, for example, as a start point of a constant curvature radius section in a curve (a point closest to the vehicle in a section with a constant curvature radius). In FIG. 16, this point corresponds to the constant curvature radius section start point Cs (= end point of the approach relaxation curve section). Further, the reference point Pcr can be selected as a point where the radius of curvature is minimum in the curve.

  In addition, the constant curvature radius section start point Cs is the point Cs1 in FIG. 4 (the node point on the foremost side in the range of the constant curvature radius section obtained from an approximate curve obtained by geometrically and smoothly connecting a plurality of node points. Or a point Cs2 in FIG. 4 (a start point (an end point on the near side) of a constant radius of curvature section obtained from the approximate curve) in FIG.

  In step 240, as shown by the line AB in FIG. 3, the target vehicle speed characteristic when the vehicle is decelerated with a preset deceleration characteristic (for example, deceleration Gxi) starting from the appropriate vehicle speed Vq at the reference point Pcr. Vt is calculated. Here, the deceleration characteristic can be a preset constant value. As shown in FIG. 3, the target vehicle speed characteristic Vt is a target of a vehicle speed reduction characteristic with respect to a position on the road, and the vehicle speed becomes an appropriate vehicle speed Vq at the reference point Pcr and is closer to the vehicle from the reference point Pcr (front side). It is a characteristic that becomes larger as it moves away toward the side. FIG. 3 shows a case where the deceleration characteristic is constant. In this case, the A-B line is an upwardly convex curve, but here, the A-B line is described as a straight line for easy understanding.

  Further, as shown by the line E-F in FIG. 3, the deceleration characteristic set in advance (for example, the same as that of the target vehicle speed characteristic Vt, starting from the appropriate vehicle speed Vq at the point Pch just before the distance Lh from the reference point Pcr). The target vehicle speed characteristic Vh for notification when the vehicle is decelerated with the deceleration characteristic) is calculated. As shown in FIG. 3, the target vehicle speed characteristic Vh for notification is also a target of the vehicle speed reduction characteristic with respect to the position on the road, and the vehicle speed becomes an appropriate vehicle speed Vq at the point Pch and from the point Pch toward the near side. It is a characteristic that becomes larger as the distance increases.

  In step 245, it is determined whether or not curve deceleration control is being executed. If curve deceleration control is not being executed, it is determined in step 250 whether or not the conditions for starting curve deceleration control are satisfied. (Start determination).

  As shown in FIG. 6, the start determination is made based on the relative distance between the curve and the vehicle, that is, the distance Lv between the reference point Pcr and the vehicle, and the vehicle speed Vx. Lv = 0 means the reference point Pcr. In FIG. 6, the upper left area (area indicated by fine dots) of the target vehicle speed characteristic Vt represents an area (deceleration control area) where deceleration control is executed. An area between the target vehicle speed characteristic Vt and the target vehicle speed characteristic Vh for notification (area indicated by hatching) is an area (notification for warning) to the driver (warning lamp lighting etc.) before starting deceleration control. Area).

  As the vehicle approaches the curve, the distance Lv decreases and the vehicle speed Vx changes according to the driving state of the driver. Along with this, the point (Lv, Vx) moves on the coordinate plane of FIG. First, a warning is given to the driver at a point where this point (Lv, Vx) crosses the characteristic Vh.

  This warning prompts the driver to operate the brake pedal BP and decelerate the vehicle. As a result, when the driver performs a relatively strong brake operation and the vehicle sufficiently decelerates, and thereafter the point (Lv, Vx) does not cross the characteristic Vt, the curve deceleration control is not started.

  On the other hand, if the driver did not perform a braking operation or a relatively weak braking operation and the point (Lv, Vx) crosses the characteristic Vt after that, the condition for starting the curve deceleration control is satisfied. Then, curve deceleration control is started. This curve deceleration control is executed regardless of the driver's acceleration / deceleration operation before the start of control.

  For example, in FIG. 6, when traveling at a constant vehicle speed (vehicle speed Vxa), when decelerating by operating a brake pedal (vehicle speed Vxb), when accelerating by operating an accelerator pedal (vehicle speed Vxc) In any case, curve deceleration control is started when the point (Lv, Vx) crosses the characteristic Vt (see points Aa, Ab, Ac). In FIG. 3, a warning is given at the point (point F) Pcu where the line representing the characteristic Vh and the line representing the transition of the vehicle speed Vx intersect (the alarm is started and continued), and the transition of the characteristic Vt and the vehicle speed Vx is represented. Curve deceleration control is started at a point (point B) Pcs where the line intersects.

  As described above, an alarm is issued when the current vehicle speed exceeds the vehicle speed at the “current position Lv of the vehicle with respect to the reference point” in the target vehicle speed characteristic Vh for notification (the notification start condition is satisfied), and then When the current vehicle speed exceeds the vehicle speed at the “current position Lv of the vehicle with respect to the reference point” in the target vehicle speed characteristic Vt, the curve deceleration control is started (the condition for starting the curve deceleration control is satisfied). Thus, the notification start condition is set to be established earlier than the start condition of the curve deceleration control.

  When the start condition for the curve deceleration control is satisfied, the curve deceleration control is started / executed at step 255. FIG. 7 is a functional block diagram related to curve deceleration control. As shown in FIG. 7, the target vehicle speed characteristic acquisition means B1 calculates the target vehicle speed Vt corresponding to the current vehicle position obtained from the target vehicle speed characteristic Vt. The vehicle speed acquisition means B2 acquires the current vehicle speed Vx.

  In the deceleration control amount calculation means B3, the deceleration control amount Gst is determined based on the deviation ΔVx (= Vx−Vt, see FIG. 3) between the vehicle speed Vx and the target vehicle speed Vt. The deceleration control amount Gst is determined to be “0” when the deviation ΔVx is negative, and is determined to be a larger value as ΔVx is larger when the deviation ΔVx is positive.

  Based on the deceleration control amount Gst, the engine output is reduced by the engine output reduction means B4 (at least one of the throttle opening reduction, the ignition timing retardation, and the fuel injection amount reduction), the transmission Any one or more of an increase (shift down, etc.) of the “reduction ratio” by the control means B5 and an application of braking torque (application of braking pressure) by wheel braking by the wheel brake control means B6 are executed. As a result, the vehicle speed Vx decreases along the target vehicle speed characteristic Vt, and is reduced to the appropriate vehicle speed Vq.

  As described above, when the curve deceleration control is being executed, it is determined at step 260 whether or not the condition for ending the curve deceleration control is satisfied. This termination condition is satisfied when the vehicle speed Vx reaches approximately the appropriate vehicle speed Vq. Specifically, as shown in FIG. 3, the curve deceleration control is terminated at a point (point G) where the decreasing vehicle speed Vx enters a minute range Hn including the appropriate vehicle speed Vq.

  If the end condition for the curve deceleration control is satisfied, at step 265, the acceleration limiting control is started / executed. That is, the wheel brake control is completely finished (braking torque and braking pressure are reduced to zero), while the acceleration is limited (throttle opening is limited) and the transmission TM is downshifted. The state continues over a continuation value (where “value” is distance or time) Ksg (see FIG. 3).

  Since the curve deceleration control is performed independently of the driver's acceleration / deceleration operation, the driver may be operating the accelerator pedal AP during the curve deceleration control. In such a case, if acceleration limitation is not performed immediately after the end of the curve deceleration control, the vehicle may accelerate suddenly (an excessive acceleration slip may occur in the drive wheels). For this reason, the acceleration limiting control is executed over a predetermined continuation value Ksg.

  In the acceleration limiting control, as shown in FIG. 3, first, acceleration is completely limited over a predetermined period (from point G to point D, from deceleration control end point to point Pca). Thereafter, the acceleration limitation (acceleration Gxo) gradually increases as the acceleration limit is gradually relaxed (from point D to point C, from point Pca to point Pco). Finally, the acceleration restriction is released (point C, point Pco).

  Here, since the driver may want to accelerate toward the end of the curve, the state is shifted down in the transmission TM for a predetermined value ("value" is distance or time) even after the acceleration restriction is released. (That is, the reduction ratio is kept constant). The curve deceleration control has been described above.

  The target vehicle speed characteristic Vt can be set to a characteristic represented by a thick solid line (curve) in FIG. 8 so that the time change amount (jerk) of the deceleration becomes small. That is, in the first half of the curve deceleration control, immediately after the deceleration control is started (point B2), the vehicle is gradually decelerated from the vehicle speed Vs, and then the deceleration is gradually increased. Thereafter, in the second half of the curve deceleration control, the deceleration is decreased, and the vehicle is slowly decelerated to the appropriate vehicle speed Vq immediately before the deceleration control ends (point A2). The driver tends to feel the change in deceleration very sensitively, so adopting such characteristics makes the smoother feeling of deceleration slower than when a constant deceleration characteristic is adopted. Can be given to the driver.

  Further, instead of the above characteristic shown by a solid line in FIG. 8, the curve is approximated by a plurality of (here, three) straight lines having different slopes (decelerations) as shown by a one-dot chain line in FIG. The obtained characteristics (deceleration Gx1a, Gx1b, Gx1c) can be adopted. In addition, in the above characteristic indicated by the solid line in FIG. 8, a characteristic may be adopted in which the deceleration is constant in either the first half or the second half of the curve deceleration control.

  In consideration of deceleration delay during curve deceleration control (for example, automatic transmission TM shift-down delay, etc.), the reference point Pcr is the starting point Cs of a constant radius of curvature section within the curve (= end of the approach relaxation curve section) It is possible to set a point on the near side (see FIG. 16) by a distance Lpr with respect to the point). As a result, the vehicle can be decelerated to the appropriate vehicle speed Vq earlier than the reference point Pcr in anticipation of the point information and the like including an error.

  In this case, the distance Lpr is determined to be a larger value as ΔVp increases based on the difference ΔVp (= Vxo−Vq) between the approach vehicle speed Vxo and the appropriate vehicle speed Vq using the table shown by the solid line in FIG. can do. Here, the approaching vehicle speed Vxo refers to the point where the curve is recognized (point Pcn in FIG. 3), the point where the alarm is started (point Pcu in FIG. 3), and the point where the curve deceleration control is started. Of the vehicle speeds at the three points (point Pcs in FIG. 3), any one vehicle speed itself, the vehicle speed (average, weighting, etc.) obtained based on any two vehicle speeds, or the three vehicle speeds Vehicle speed (average, weighting, etc.) obtained based on

  Further, as indicated by a solid line in FIG. 9, the distance Lpr can be determined to be larger as the appropriate vehicle speed Vq is larger. Furthermore, the distance Lpr can be set to a larger value as the vehicle speed Vxo is larger, or can be set to a larger value as the minimum curvature radius Rm is larger. This is because, as the vehicle speed increases, it is necessary to start deceleration earlier as the vehicle speed increases, considering that the error in the moving distance of the vehicle due to the error in the point information and the like increases.

  Furthermore, as indicated by a broken line in FIG. 9, when the vehicle is accelerating at any of the three points, the distance Lpr is set to a larger value than when the vehicle is traveling at a constant speed. can do. Similarly, when the vehicle tends to decelerate at any of the three points, the distance Lpr can be set to a smaller value than when the vehicle is traveling at a constant speed.

  The continuation value Ksg (see FIG. 3) of the acceleration limiting control described above becomes larger as Lit becomes larger based on the distance Lit (see FIG. 16) of the constant radius of curvature section using the table shown in FIG. A large value can be determined (lower limit Ksg0). This is based on the fact that the shorter the lit, the earlier the acceleration restriction is released, thereby reducing the sense of discomfort given to the driver by the acceleration restriction.

  Further, the continuation value Ksg can be determined to be a larger value as Vq increases based on the appropriate vehicle speed Vq using the table shown in FIG. This is based on the fact that when the accelerator pedal AP is operated before the acceleration restriction is released, the greater the appropriate vehicle speed Vq, the greater the degree of acceleration slip of the drive wheels that can occur immediately after the acceleration restriction is released.

  By the way, there may be a case where two or more continuous curves such as a so-called S-shaped curve and a composite curve (for example, consisting of an approach relaxation curve section, a constant curvature radius section, and an exit relaxation curve section) continue. In such a case, two or more curves in front of the vehicle can be recognized. For example, FIG. 12 shows a case where two curves (the back curve has a smaller minimum radius of curvature) are recognized.

  In this case, as shown in FIG. 12, the reference point (Pcr1, Pcr2) and the appropriate vehicle speed (Vq1, Vq2) are determined for each curve, and the target vehicle speed characteristics are determined for each curve based on the corresponding reference point and the appropriate vehicle speed. (Vt1, Vt2) is determined. Then, the curve deceleration control is executed based on the target vehicle speed characteristic (Vt2 in FIG. 12) that satisfies the above-described curve deceleration control start condition (see FIG. 6). That is, in FIG. 12, the vehicle is decelerated from the vehicle speed Vs2 by the curve deceleration control at the point (point B2) Pcs. As a result, the curve deceleration control can be executed based on the curve that is required to be decelerated earlier among the two curves (the curve on the back side in FIG. 12).

  In addition, the road surface friction coefficient may decrease during execution of the curve deceleration control, such as when ice or snow remains in the curve. FIG. 13 shows a case where the road surface friction coefficient decreases after the point Plm between the point Pcs where the curve deceleration control is started and the reference point Pcr. Even in such a case, the curve deceleration control described above is not terminated when the vehicle position reaches the reference point Pcr, but is executed until the vehicle speed Vx enters the minute range Hn including the appropriate vehicle speed Vq. Is done. For this reason, the curve deceleration control is continued even after passing the reference point Pcr, and the vehicle can be surely decelerated to the appropriate vehicle speed Vq.

  FIG. 14 shows an example when the curve deceleration control is executed by this apparatus. When the vehicle passes through the point Pcs where the start condition of the curve deceleration control described above is satisfied, the curve deceleration control is started. As a result, the throttle opening is limited (up to the upper limit value but not larger than the upper limit value), the reduction ratio of the transmission TM is increased (shift down to change the gear stage from Tr to Ts), and Application of braking torque (braking pressure) by the wheel brake is started.

  The vehicle is gradually decelerated by the curve deceleration control, and the curve deceleration control is terminated at a point where the vehicle speed Vx substantially matches the appropriate vehicle speed Vq (near the reference point Pcr). Thereby, while the braking torque of the wheel brake becomes “0”, the above-described acceleration restriction control is started subsequently. For this reason, until the vehicle passes through the point Pca, the throttle opening limit (upper limit value = 0) is provided, and then the limit is gradually weakened, and the restriction is limited when the vehicle passes through the point Pco. Completely released. At this time, in preparation for the driver's acceleration operation, the transmission TM is still maintained in the downshifted state (shift stage = Ts) until the vehicle passes the point Pce. However, when the driver's acceleration operation is not performed, a shift up is performed in which the gear position is changed from Ts to Tr.

  Further, as described above, the target vehicle speed characteristic Vt is used as the control start condition for the curve deceleration control. On the other hand, after the curve deceleration control is started, the deceleration control is performed based on the target deceleration without using the target vehicle speed characteristic Vt. It can be carried out. As described above, when the curve deceleration control is performed using the deviation ΔVx (see FIG. 3), the vehicle deceleration changes microscopically in order to achieve the target vehicle speed characteristic Vt. Therefore, after the start of deceleration control is determined using the target vehicle speed characteristic Vt, deceleration control (for example, braking pressure control of the wheel brake) is executed so that the vehicle deceleration matches the target deceleration. The

  Thereby, since the deceleration of the vehicle is directly controlled, the microscopic deceleration change of the vehicle can be suppressed as compared with the case where the deviation ΔVx is used. On the other hand, there is a possibility that a point where the vehicle speed Vx substantially coincides with the appropriate vehicle speed Vq is separated from the reference point Pcr (deceleration control error). However, even in this case, since the deceleration control is terminated when the vehicle speed Vx substantially matches the appropriate vehicle speed Vq, the vehicle speed Vx can be reliably reduced to the appropriate vehicle speed Vq. Further, as described above, by setting the reference point Pcr closer to the start point of the constant curvature radius section of the curve, the above-described deceleration control error can be absorbed.

  As described above, when the curve deceleration control is performed using the target deceleration, the target deceleration Gxt is set based on the above-described “distance Lv between the reference point Pcr and the vehicle” as shown in FIG. Can do. As indicated by the solid line in FIG. 15, the target deceleration Gxt can be set to a relatively small value immediately after the start of the curve deceleration control, and then gradually increased. Furthermore, as indicated by a broken line in FIG. 15, the target deceleration Gxt can be gradually decreased as it approaches the reference point Pcr after being increased. Thereby, the same effect as the case shown in FIG. 8 is acquired. That is, the deceleration control starts with a gradual deceleration and then a strong deceleration, which matches the driver's feeling. In addition, since the deceleration is relaxed at the end of the deceleration control, it is possible to suppress the time change (jerk) of the deceleration.

  Also, if the driver operates the brake pedal BP during curve deceleration control, the vehicle deceleration requested by the driver (requested deceleration Gdr) is compared with the vehicle deceleration Gcv in curve deceleration control. When the required deceleration Gdr is larger than the vehicle deceleration Gcv (Gdr> Gcv, Gdr, Gcv are positive values), the curve deceleration control is terminated and the vehicle is decelerated according to the driver's brake pedal operation. The On the other hand, when the required deceleration Gdr is equal to or less than the vehicle deceleration Gcv (Gdr ≦ Gcv, Gdr, and Gcv are positive values), the curve deceleration control is continued. This is to ensure the degree of deceleration of the vehicle necessary for traveling on the curve at the appropriate vehicle speed Vq.

  Here, the required deceleration Gdr is determined based on the braking operation amount Bs detected by the braking operation amount sensor BS. The vehicle deceleration Gcv for curve deceleration control is the longitudinal acceleration (deceleration) Gx detected by the longitudinal acceleration sensor GX during curve deceleration control, the deceleration characteristics of the curve deceleration control (for example, deceleration Gxi), the target deceleration Gxt, It is calculated based on at least one of the deceleration control amounts Gst.

  Further, when the driver is operating the brake pedal BP, the acceleration restriction control after the end of the curve deceleration control is not performed. This is because the driver does not operate the accelerator pedal AP, and therefore it is not necessary to limit unnecessary acceleration slip.

  As described above, according to the motion control apparatus according to the embodiment of the present invention, the curve deceleration control is performed so that the vehicle speed Vx is curved at the reference point Pcr in the middle of the curve (for example, at the end point of the approach relaxation curve section or in front thereof). The vehicle is executed regardless of whether or not the driver performs acceleration / deceleration operation, with the goal of reducing the vehicle speed to an appropriate vehicle speed Vq for traveling properly. That is, this curve deceleration control can be started regardless of whether the vehicle has entered the curve.

  In addition, when the vehicle is decelerated to the appropriate vehicle speed Vq, the curve deceleration control is terminated regardless of whether the vehicle has left the curve. As described above, curve deceleration control (particularly, the start timing and end timing) tends to be in line with the driver's intention according to the shape of the curve, and as a result, the uncomfortable feeling given to the driver by the curve deceleration control is reduced. be able to.

  Further, the acceleration limiting control is executed for a predetermined period following the end of the curve deceleration control. Therefore, in the case where the driver is operating the accelerator pedal AP during the curve deceleration control, it is possible to suppress the degree of sudden acceleration of the vehicle (acceleration slip of the drive wheels) that can occur immediately after the completion of the curve deceleration control. it can.

1 is a schematic configuration diagram of a vehicle equipped with a vehicle motion control device according to an embodiment of the present invention. It is the flowchart which showed the routine for performing curve deceleration control which the electronic control unit of the apparatus shown in FIG. 1 performs. It is the graph which showed an example of the relationship between the position on the road of a vehicle, and a vehicle speed. It is the graph which showed the relationship between the position on a road, and the curvature radius of a curve. It is the graph which showed the relationship between the minimum curvature radius and the appropriate vehicle speed. It is a figure for demonstrating the start conditions of curve deceleration control. It is a functional block diagram concerning curve deceleration control. It is the graph which showed the modification of the target vehicle speed characteristic used for curve deceleration control. It is the graph which showed the table used when setting the distance from the starting point of the fixed curvature radius section of a reference point when a reference point is set in the near side to the starting point of a fixed curvature radius section. . It is the graph which showed the relationship between the distance of a fixed curvature radius area, and the continuation value of acceleration limitation control. It is the graph which showed the relationship between a suitable vehicle speed and the continuation value of acceleration limitation control. It is a figure for demonstrating the curve deceleration control performed when two curves are recognized. It is the figure which showed the example when the road surface friction coefficient fell during curve deceleration control execution. It is the figure which showed an example at the time of curve deceleration control being performed by the apparatus shown in FIG. 6 is a graph showing a relationship between a position on a road and a target deceleration when curve deceleration control is performed using the target deceleration. It is a figure for demonstrating the shape of a curve.

Explanation of symbols

  BP ... brake pedal, AP ... accelerator pedal, SF ... shift lever, WS ** ... wheel speed sensor, PW ** ... brake pressure sensor, TS ... throttle valve opening sensor, HS ... shift position sensor, TH ... throttle actuator, FI ... Fuel injection actuator, BRK ... Brake actuator, TM ... Automatic transmission, EG ... Engine, ECU ... Electronic control unit, NAV ... Navigation device, GPS ... Global positioning system, MAP ... Memory

Claims (5)

Vehicle speed acquisition means for acquiring the vehicle speed of the vehicle;
Shape acquisition means for acquiring the shape of a curve in front of the vehicle on the road on which the vehicle is traveling;
Position acquisition means for acquiring a relative position of the vehicle with respect to the curve;
A reference point is determined based on the shape of the curve and the end point of the relaxation curve section on the approaching side of the curve, and when the vehicle passes the determined reference point based on the shape of the curve. A determination means for determining an appropriate vehicle speed;
Based on the reference point and the appropriate vehicle speed, the vehicle speed reduction characteristic target for the position on the road when the vehicle is decelerated on the road closer to the vehicle from the reference point. Computing means for computing a certain target vehicle speed characteristic;
Deceleration control for decelerating the vehicle when a relationship between the vehicle speed and the position of the vehicle with respect to the reference point obtained from the relative position satisfies a control start condition determined based on the target vehicle speed characteristic. Deceleration control means for starting and ending the deceleration control when the vehicle speed reaches a predetermined range including the appropriate vehicle speed;
When the driver of the vehicle operates the accelerator pedal of the vehicle, the vehicle travels a predetermined distance from the end point of the deceleration control or the vehicle travels a predetermined distance from the end point of the deceleration control. Acceleration limiting control means for limiting the degree of acceleration of the vehicle;
A vehicle motion control apparatus comprising:   The vehicle motion control device according to claim 1,
  The acceleration restriction control means includes
  A vehicle motion control device configured not to limit the degree of acceleration of the vehicle when a driver of the vehicle is operating a brake pedal of the vehicle. In the vehicle motion control apparatus according to claim 1 or 2 ,
The acceleration restriction control means includes
A vehicle motion control device configured to determine the predetermined time or the predetermined distance based on a distance of a constant curvature radius section in the curve. In the vehicle motion control apparatus according to any one of claims 1 to 3 ,
When the shape acquisition means acquires the shape of two or more curves in front of the vehicle,
The determining means includes
For each curve, the reference point and the appropriate vehicle speed are determined,
The computing means is
For each of the curves, a characteristic corresponding to the target vehicle speed characteristic is determined based on a preset deceleration, the corresponding reference point, and the appropriate vehicle speed, and among the two or more characteristics, the characteristics Motion control of a vehicle configured to employ, as the target vehicle speed characteristic used by the deceleration control means, a characteristic corresponding to a condition that can be satisfied at an earliest among the control start conditions respectively determined based on apparatus. The vehicle motion control apparatus according to any one of claims 1 to 4 ,
The target vehicle speed characteristic calculated by the calculation means is a characteristic in which the deceleration of the vehicle increases in the first half of the deceleration control and / or a characteristic in which the deceleration decreases in the second half of the deceleration control. A vehicle motion control device comprising:

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