JP4790491B2 - Automatic braking control device - Google Patents

Description

  The present invention is used for large vehicles (trucks, buses) for transporting cargo and passengers.

  The electronic control of automobiles has progressed steadily, and events that have so far depended solely on the judgment of the driver have been carried out by onboard computers.

  As an example, the distance between the preceding vehicle and the host vehicle (inter-vehicle distance) is monitored by a radar, and when the inter-vehicle distance approaches abnormally, appropriate braking control is automatically performed to prevent a collision. Sometimes, there is an automatic braking control device that minimizes the damage (see, for example, Patent Document 1).

JP 2005-31967 A Japanese Patent Laid-Open No. 11-180274

  The above-described automatic braking control device has already been put into practical use in passenger cars, but it must be solved when a similar function is to be used for large vehicles (trucks, buses) for transporting cargo and passengers. There is a problem that must be done.

  In other words, large vehicles have an extremely large mass compared to passenger cars, and in addition to the driver's own safety, the safety of passengers and cargo must be ensured. It is difficult to achieve the intended purpose with simple simple braking control, and it is necessary to perform more advanced automatic braking control than in the case of passenger cars. However, since such means has not been established, automatic braking control devices for trucks and buses have not yet been put into practical use.

  The present invention has been made under such a background, and an object thereof is to provide an automatic braking control device that can realize automatic braking control in a truck or a bus.

  The present invention is an automatic braking control device provided with a control unit that automatically performs braking control without a driving operation based on a sensor output including a distance from an object in the traveling direction of the host vehicle.

  Here, the feature of the present invention is that the control means includes the object and the vehicle derived based on a relative distance and a relative speed between the object and the vehicle obtained by the sensor output. Stepwise braking control that gradually increases the braking force or braking deceleration over multiple stages in a time-series manner automatically when the estimated time required to become less than the predetermined distance falls below the set value The vehicle is provided with braking control means, and the vehicle is provided with attitude control means for detecting a side slip of the own vehicle and suppressing the side slip of the own vehicle when the side slip of the own vehicle is detected. Is provided with means for prohibiting the stepwise braking control when the side slip suppression control by the posture control means is executed before or during execution of the stepwise braking control. The posture control means includes means for detecting a side slip of the host vehicle by detecting, for example, idling of a wheel.

  The predicted time required for the object and the vehicle to be derived based on the relative distance and relative speed between the object and the vehicle is equal to or less than a predetermined distance is, for example, a collision between the object and the vehicle This is the estimated time required to do this (hereinafter referred to as TTC (Time To Collision)).

  That is, the automatic braking control device of the present invention is a device that can reduce the impact at the time of collision while maintaining the stability of the vehicle even in large vehicles such as trucks and buses by performing stepwise braking control. is there.

  On the other hand, under conditions where the coefficient of friction of the road surface is small, such as when it is raining or snowing, it is undeniable that a slip will occur due to braking of the host vehicle and the vehicle will slip sideways. Attitude control means for suppressing a side slip including a side slip caused by such a slip is known (for example, see Patent Document 2).

  In situations where the friction coefficient of the road surface is small such that side slip suppression control by such posture control means is executed, if automatic braking control is not intentionally performed, it is rather possible to reduce damage by leaving the operation to the driver There is also. Therefore, in the present invention, when side slip suppression control by the attitude control means is executed before or during execution of stepwise braking control, stepwise braking control is prohibited.

  In addition, since the automatic braking control device is originally a safety measure means assuming a driver's side-by-side driving or dozing operation, when the stepwise braking control is prohibited by the prohibiting means, the driver's attention should be paid. It is desirable to provide a means for issuing an alarm to alert.

  In addition, when the host vehicle speed is less than a predetermined value and the value taken by the steering angle or yaw rate is out of the predetermined range, a means for prohibiting activation of the stepwise braking control means can be provided.

  That is, the stepwise braking control performed by the automatic braking control device of the present invention is, for example, when the vehicle speed before starting the braking control is 60 km / h or more, and a large steering wheel operation such as when changing lanes or driving sharp curves is performed. Since it is assumed to be used in a state where it is not performed, the start of the stepwise braking control can be restricted in other traveling states.

  For example, if the vehicle speed before the start of braking control is less than 60 km / h, the vehicle has less kinetic energy, so there is no problem even if simple sudden braking control as conventionally applied to passenger cars is performed. Limit the start of stepwise braking control. Also, for example, if the steering angle before starting the braking control is + 30 ° or more or −30 ° or less, this means that the vehicle is changing lanes or driving in a sharp curve. Restrict. In this case, a yaw rate may be used instead of the steering angle.

  According to the present invention, automatic braking control in a truck or bus can be realized. In particular, it is possible to cope with the occurrence of side slip at the time of braking control.

  An automatic braking control apparatus according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a control system configuration diagram of the present embodiment. FIG. 2 is a flowchart showing a control procedure in the attitude control ECU. FIG. 3 is a flowchart showing a braking control procedure in the braking control ECU of this embodiment. FIG. 4 is a diagram showing a braking pattern at the time of the idle control that the braking control ECU has. FIG. 5 is a diagram showing a braking pattern at the time of half product of the braking control ECU. FIG. 6 is a diagram showing a braking pattern at the time of fixed volume possessed by the braking control ECU. FIG. 7 is a diagram showing a full-scale braking pattern that the braking control ECU has.

  As shown in FIG. 1, the braking control ECU 4, the gateway ECU 5, the meter ECU 6, the engine ECU 8, the axle weight meter 9, the EBS (Electric Breaking System) _ECU 10, and the attitude control ECU 16 are connected to each other via a VehicleCAN (J1939) 7.

  The steering sensor 2, the yaw rate sensor 3, the vehicle speed sensor 13, and the wheel speed sensor 14 are connected to the VehicleCAN (J1939) 7 via the gateway ECU 5, and the sensor information is taken into the braking control ECU 4. The brake control is performed by the EBS_ECU 10 driving the brake actuator 11. Note that the brake instruction to the EBS_ECU 10 is performed by the brake operation and braking control ECU 4 at the driver's seat (not shown). The brake information including information on the brake operation by the driver is also output from the EBS_ECU 10 and taken into the brake control ECU 4. The engine ECU 8 performs fuel injection amount control of the engine 12 and other engine control. Note that the injection amount control instruction to the engine ECU 8 is performed by the accelerator operation of the driver's seat. Further, the alarm display and buzzer sound output by the braking control ECU 4 are displayed on the display unit (not shown) of the driver's seat by the meter ECU 6. Since the control system related to steering other than the steering sensor 2 is not directly related to the present invention, the illustration is omitted.

  In this embodiment, as shown in FIG. 1, a millimeter wave radar 1 for measuring a distance from a preceding vehicle or a falling object such as a falling object in the traveling direction of the own vehicle, a steering sensor 2 for detecting a steering angle, This is an automatic braking control device including a braking control ECU 4 that automatically performs braking control based on sensor outputs such as a yaw rate sensor 3 for detecting the yaw rate and a vehicle speed sensor 13 for detecting the host vehicle speed without any driving operation. .

  The braking control ECU 4 automatically detects when the TTC derived based on the relative distance and relative speed between the object and the vehicle obtained from the sensor outputs from the millimeter wave radar 1 and the vehicle speed sensor 13 falls below a set value. Therefore, stepwise braking control is performed in which the braking force is gradually increased over a plurality of stages in time series. In this stepwise braking control, for example, as shown in FIG. 4, the braking force is gradually increased over three stages in time series.

  In the example of FIG. 4, first, in the first stage marked “alarm”, braking of about 0.1 G is applied from TTC 2.4 seconds to 1.6 seconds. At this stage, the so-called sudden braking is not yet applied, and the stop lamp is lit to notify the following vehicle that the sudden braking will be performed. Next, in the second stage described as “enlarged area braking”, braking of about 0.3 G is applied from TTC 1.6 seconds to 0.8 seconds. Finally, in the third stage, marked as “full-scale braking”, the maximum braking (about 0.5 G) is applied from TTC 0.8 seconds to 0 seconds.

  When the driver performs a strong braking operation exceeding the braking force shown above, the stronger braking force is given priority. However, the driver's braking operation acts as a brake instruction to the EBS_ECU 10, and the driver has an ABS (Antilock Brake System) function or a running posture stabilization function even if the driver should perform an excessive braking operation. The EBS_ECU 10 appropriately adjusts the braking force of the brake actuator 11 based on these functions. In the case of the present embodiment, an attitude control ECU 16 described later is provided as a running attitude stabilization function. The ABS function is not mentioned because it has no direct relationship with the present invention.

  In the following description, the preceding vehicle will be described, but the automatic braking control device of this embodiment is also effective for falling objects on the road.

  The host vehicle is provided with an attitude control ECU 16 that detects a side slip of the host vehicle and suppresses the side slip of the host vehicle when the side slip of the host vehicle is detected. For example, the attitude control ECU 16 detects a side slip of the host vehicle by a wheel speed sensor 14 that detects the idling of the wheel, and executes appropriate side slip suppression control when the side slip is detected. The attitude control ECU 16 detects the side slip by detecting the idling of the wheels by the wheel speed sensor 14 and using a number of other parameters such as the vehicle speed, the acceleration of the vehicle, the yaw rate of the vehicle, and the like. Although there is an enhanced technique (for example, refer to Patent Document 2), in this embodiment, a technique using wheel idling detection by the wheel speed sensor 14 will be described in order to make the explanation easy to understand.

  The brake control ECU 4 prohibits the stepwise brake control when the side slip prevention control is executed by the attitude control ECU 16 before or during the stepwise brake control. Further, when the stepwise braking control is prohibited, an alarm for alerting the driver is issued.

  In other words, under circumstances where the coefficient of friction of the road surface is small such that the side-slip suppression control by the attitude control ECU 16 is executed, there is a case in which it is rather possible to reduce the damage by leaving the automatic braking control to the operation by the driver. is there. Therefore, in this embodiment, when the side slip suppression control by the attitude control ECU 16 is executed before or during the execution of the stepwise braking control, the braking control ECU 4 prohibits the stepwise braking control.

  Further, since the automatic braking control device is originally a safety measure means assuming a driver's side-by-side driving or dozing operation, an alarm that alerts the driver when the braking control ECU 4 prohibits stepwise braking control. Issue. The alarm is provided in the driver's seat via the meter ECU 6 and is displayed on a display unit (not shown). This display unit is, for example, a speaker or a display panel, and displays a warning to the driver by a buzzer sound or flashing light.

  Here, the control procedure of the attitude control ECU 16 will be described with reference to FIG. As shown in FIG. 2, the attitude control ECU 16 acquires wheel speed information from the wheel speed sensor 14 (S1), and detects whether or not attitude control is necessary (S2). For example, if the wheel speeds of the right rear wheel and the left rear wheel are compared and one of the wheel speeds is significantly faster than the other wheel speed, one of the left and right wheels is in a slip state and the other is locked. You can see that it is in a state. Such a state represents a side slip state. When such a side slip state is detected, for example, posture control information that reduces the braking force of the rear wheel in the locked state is output (S3). This is an instruction for restoring the grip force of the rear wheel in the locked state so that the left and right rear wheels can exert the braking force evenly. Note that the detailed method of posture control is already a known method as disclosed in, for example, Patent Document 2, and thus detailed description thereof is omitted here.

  4, 5, and 6 are diagrams showing braking patterns that the braking control ECU 4 has at the time of empty product, half product, and constant product, respectively, which are shown in FIGS. 4, 5, and 6. As described above, the braking pattern selection unit 40 of the braking control ECU 4 selects a braking pattern according to the loaded cargo or the weight of the passenger. As a selection method, a plurality of control patterns for “empty product”, “half product”, and “constant product” are stored in advance in the braking pattern storage unit 41 of the braking control ECU 4, and the braking pattern selection unit 401. Can be realized by selecting a braking pattern that matches (or approximates) these braking patterns according to the weight. The weight information of the loaded cargo and passengers is obtained by the axle weight meter 9 shown in FIG. 1 and is taken into the braking control ECU 4.

  Further, when the host vehicle speed is less than 60 km / h and the steering angle is not less than +30 degrees or not more than -30 degrees, the braking control ECU 4 prohibits the start of the stepwise braking control. A yaw rate may be used instead of the steering angle.

  In other words, the stepwise braking control performed by the automatic braking control device of this embodiment is such that the host vehicle speed before starting the braking control is 60 km / h or more, and a large steering wheel operation such as when changing lanes or driving sharp curves is performed. Since it is assumed that the vehicle is not used, it is possible to limit the start of the stepwise braking control in other driving conditions.

  Also, if the vehicle speed before the start of braking control is less than 60 km / h, the vehicle has less kinetic energy, so there is no problem even if simple sudden braking control as conventionally applied to passenger cars is performed. Since the usefulness of performing stepwise braking control is low, the activation of stepwise braking control is limited. Alternatively, if the steering angle before the start of the braking control is +30 degrees or more or -30 degrees or less, this means that the vehicle is changing lanes or traveling sharply. Restrict startup of. In this case, a yaw rate may be used instead of the steering angle.

  In this embodiment, when the vehicle speed before the start of the braking control is less than 60 km / h and not less than 15 km / h, the stepwise braking control is not performed, but as shown in FIG. Only the full-scale braking control shown in FIG. 6 (b) is performed. When only such full-scale braking control is performed, braking control equivalent to conventional automatic braking control used for passenger cars can be applied. In addition, when applying such automatic braking control equivalent to the conventional one, there is no need to determine whether or not the vehicle is changing lanes or traveling sharply.

  Next, the operation of the automatic braking control device of this embodiment will be described with reference to the flowchart of FIG. 3 will be described with reference to an example of a braking pattern at the time of idle product (FIG. 4), but the procedure of the flowchart of FIG. 3 also at other braking patterns (half product (FIG. 5), fixed product (FIG. 6)). According to As shown in FIG. 3, the braking control ECU 4 measures and monitors the inter-vehicle distance from the preceding vehicle and the vehicle speed of the preceding vehicle by the millimeter wave radar 1. Further, the vehicle speed is measured by the vehicle speed sensor 13 and monitored. Further, the weight of the loaded cargo and passengers is measured and monitored by the axle weight meter 9. The braking pattern selection unit 40 of the braking control ECU 4 selects in advance a braking pattern that matches (or approximates) from the braking patterns (FIGS. 4 to 6) based on the measurement result of the weight (S11). The following description is an example in which the braking pattern of FIG. 4 is selected. Further, the braking control ECU 4 monitors whether or not the side slip prevention control is executed by the posture control ECU 16 based on the posture control information of the posture control ECU 16.

Subsequently, the braking control ECU 4 calculates TTC from the inter-vehicle distance, the own vehicle speed, and the vehicle speed of the preceding vehicle (S12). The calculation method is
Distance between vehicles / (Self-vehicle speed-Vehicle speed of the preceding vehicle)
It is. In the braking control ECU 4, the vehicle speed before starting the braking control is 60 km / h or more (S13), the steering angle before starting the braking control is +30 degrees or less and -30 degrees or more (S14), and the TTC is shown in FIG. If it is in the region (1) shown in (a) (S15), and if the side-slip suppression control is not executed by the attitude control ECU 16 (S18) at this time, "alarm" braking control is executed (S19). Further, if the TTC is in the region (1) shown in FIG. 4A (S15), and if the side slip suppression control is executed by the attitude control ECU 16 at this time (S18), the braking control is prohibited and the driving is performed. A warning is issued to the person (S18).

  Further, if the TTC is in the region (2) shown in FIG. 4A (S16), and if the side slip suppression control is not executed by the attitude control ECU 16 at this time (S20), the “enlarged region braking” control is performed. Execute (S21). Further, if the TTC is in the region (2) shown in FIG. 4A (S16), and if the side slip suppression control is executed by the attitude control ECU 16 at this time (S20), the braking control is prohibited and the driving is performed. A warning is issued to the person (S28).

  Further, if the TTC is in the region (3) shown in FIG. 4A (S17), and if the side slip suppression control is not executed by the attitude control ECU 16 at this time (S22), the “full-scale braking” control is executed. (S23). Further, if the TTC is in the region (3) shown in FIG. 4A (S17), and if the side slip suppression control is executed by the attitude control ECU 16 at this time (S22), the braking control is prohibited and the driving is performed. A warning is issued to the person (S28).

  Further, if the host vehicle speed before starting the braking control is less than 60 km / h and 15 km / h or more (S13, S24), and the TTC is in the region (4) shown in FIG. 4C (S25), the braking control ECU 4 Notifies the driver that the relative distance from the preceding vehicle is short (S26). Notification is performed by warning display or buzzer sound.

  Further, if the TTC is in the region (5) shown in FIG. 4C (S27), and if the side slip suppression control is not executed by the attitude control ECU 16 at this time (S22), the “full-scale braking” control is executed. (S23). Further, if the TTC is in the region (5) shown in FIG. 4C (S27), and if the slip control is executed by the attitude control ECU 16 at this time (S22), the braking control is prohibited and the driving is prohibited. A warning is issued to the person (S28).

  For detecting the steering angle, the yaw rate from the yaw rate sensor 3 can be used instead of the steering angle from the steering sensor 2. Alternatively, the steering angle and the yaw rate may be used in combination.

  Here, FIG. 4 to FIG. 6 will be described. The straight lines c, f, i, and l in FIGS. 4 to 6 are called steering avoidance limit straight lines. Also, curves B, D, F, and H in FIGS. 4 to 6 are called braking avoidance limit curves.

  That is, the steering avoidance limit straight line is a straight line indicating a limit at which a collision can be avoided by a steering operation within a predetermined TTC in the relationship between one relative distance to the obstacle and one relative speed with the obstacle. The braking avoidance limit curve is a curve indicating a limit at which a collision can be avoided by a braking operation within a predetermined TTC in the relationship between one relative distance to the obstacle and one relative speed with the obstacle.

  In FIGS. 4 to 6, in the area under both of these straight lines or curves, the collision can no longer be avoided by the steering operation or the braking operation.

  For example, in the example of the empty product in FIG. 4, the straight line c has TTC set to 0.8 seconds. In the present embodiment, a straight line b when the TTC is 1.6 seconds is provided above the steering avoidance limit straight line c, and a straight line a when the TTC is 2.4 seconds is provided. Further, a curve A with TTC set at 1.6 seconds is provided above the braking avoidance limit curve B with TTC set at 0.8 seconds.

  The initial state of the vehicle has a relative distance and a relative speed with respect to the obstacle indicated by a black point G in FIG. When the host vehicle speed before the start of braking control is 60 km / h or more, the relative distance gradually decreases, and when the vehicle reaches the position of the straight line a, the alarm mode is set (area (1)). In the alarm mode, braking of about 0.1 G is applied from TTC 2.4 seconds to 1.6 seconds. During this period, it is meaningful to turn on the stop lamp and inform the subsequent vehicle of braking. When the relative speed further decreases and reaches the position of the straight line b, the expansion area braking mode is set (area (2)). In the enlarged area braking mode, braking of about 0.3 G is applied from TTC 1.6 seconds to 0.8 seconds. When the position of the straight line c is reached, the full braking mode is set (area (3)). In the full-scale braking mode, the maximum braking force (about 0.5G) is applied from TTC 0.8 seconds to 0 seconds. According to the calculation in step S12 in FIG. 3, a collision occurs at this time. However, the actual TTC is longer than the calculation result of step S12.

  In other words, in the calculation of TTC in the automatic braking control device targeted by the present invention, precise distance measurement and complicated calculation processing are omitted as much as possible, and a general-purpose simple distance measurement device (for example, millimeter wave radar) or a calculation device is used. It is assumed that. Such considerations are useful for keeping vehicle manufacturing costs or maintenance costs low.

  Therefore, strictly speaking, the preceding vehicle and the subject vehicle, which are the objects, are performing a uniform acceleration motion by braking (deceleration), and therefore the TTC calculation must also be calculated based on the uniform acceleration motion. By calculating the TTC as simply performing constant velocity motion, precise distance measurement and complicated arithmetic processing are omitted.

  In addition, by performing a calculation that is regarded as such a constant velocity motion, the calculated TTC value becomes smaller than the actual TTC value. There is no hindrance.

  Further, when the host vehicle speed before starting the braking control is 15 km / h or more and less than 60 km / h, the relative distance is gradually shortened, and when the vehicle reaches the position of the straight line b, the notification mode is set (region (4)). . In the notification mode, the driver is notified that the relative distance to the obstacle is shortened by an alarm display or a buzzer sound. When the position of the straight line c is reached, the full braking mode is set (area (5)). In the full-scale braking mode, the maximum braking force (about 0.5G) is applied from TTC 0.8 seconds to 0 seconds.

  In this embodiment, such stepwise braking control is prohibited during execution of the side slip suppression control by the attitude control ECU 16.

In addition, since the braking distance increases as the weight of the loaded cargo or passenger increases, the steering avoidance limit straight line and the braking avoidance limit curve also move upward in the figure. Thereby, regions (1), (2), (3)
, (4), (5) area increases according to the weight of the loaded cargo and passengers.

  4 correspond to the straight lines d to f in FIG. 5 and the straight lines g to i in FIG. 6, and the curves A and B in FIG. 4 are the curves C and D in FIG. 5 and the curve E in FIG. , F, and the black point G in FIG. 4 corresponds to the black point H in FIG. 5 and the black point I in FIG.

  ADVANTAGE OF THE INVENTION According to this invention, the automatic braking control in a truck or a bus | bath can be implement | achieved, and it can contribute to traffic safety. In particular, it is possible to cope with the occurrence of side slip at the time of braking control.

The control system block diagram of a present Example. The flowchart which shows the control procedure in attitude | position ECU. The flowchart which shows the brake control procedure in brake control ECU of a present Example. The figure which shows the braking pattern at the time of the idle product which braking control ECU has. The figure which shows the braking pattern at the time of the half product which braking control ECU has. The figure which shows the braking pattern at the time of the fixed volume which braking control ECU has. The figure which shows the full-scale braking pattern which braking control ECU has.

Explanation of symbols

1 Millimeter wave radar 2 Steering sensor 3 Yaw rate sensor 4 Braking control ECU
5 Gateway ECU
6 Meter ECU
7 VehicleCAN (J1939)
8 Engine ECU
9 Shaft weigher 10 EBS_ECU
11 Brake actuator 12 Engine 13 Vehicle speed sensor 14 Wheel speed sensor 16 Attitude control ECU
40 Braking pattern selection unit 41 Braking pattern storage unit

Claims (4)

Control means for automatically performing braking control without a driving operation based on a sensor output including a distance from an object in the traveling direction of the host vehicle,
The control means calculates an estimated time required for the object and the vehicle to collide based on a relative distance and a relative speed between the object and the vehicle obtained from the sensor output, and the estimated time Stepwise braking control means for automatically performing stepwise braking control when the time falls below the set time,
This stepwise braking control means is a braking control means for increasing the braking force or braking deceleration in three stages in a time series including the first braking stage, the second braking stage, and the third braking stage.
The braking in the first braking stage, the second braking stage, and the third braking stage is such that a constant amount of braking force or braking deceleration is continuously given,
When the predicted time falls below a preset predetermined time before a limit time that can avoid a collision by a braking operation, the braking of the first braking stage is continuously applied until a limit time that can avoid a collision by the braking operation,
When the predicted time is less than a limit time that can avoid a collision by the braking operation, the braking of the second braking stage is continuously given until a limit time that can avoid a collision by a steering operation,
An automatic braking control device that continuously applies braking in a third braking stage when the predicted time is less than a time limit for avoiding a collision by a steering operation,
The own vehicle is provided with posture control means for detecting the side slip of the own vehicle and suppressing the side slip of the own vehicle when the side slip of the own vehicle is detected,
The stepwise braking control means includes means for prohibiting the stepwise braking control when side slip suppression control by the posture control means is executed before or during execution of the stepwise braking control. An automatic braking control device.   2. The automatic braking control device according to claim 1, wherein the attitude control means includes means for detecting a side slip of the host vehicle by detecting idling of a wheel.   2. The automatic braking control device according to claim 1, further comprising a means for issuing an alarm for alerting the driver when the stepwise braking control is prohibited by the prohibiting means.   4. The vehicle according to claim 1, further comprising means for prohibiting start of the stepwise braking control means when the host vehicle speed is less than a predetermined value and the value of the steering angle or yaw rate is outside the predetermined range. Automatic braking control device.

Images