JP2007084049A - Automatic brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain an automatic brake control for truck and bus. <P>SOLUTION: A stepwise brake control is automatically performed, when TTC obtained on the basis of a relative distance and relative speed between a target and an own vehicle is lower than a predetermined value. The stepwise brake control detects the normal drive condition of a driver when the driver serially performs a brake control gradually increasing brake force or brake deceleration speed in two or more steps, and reduces the number of stepwise control, when the normal drive condition of the driver is detected. The stepwise brake control decides that the driver is in normal driving conditions, until a predetermined time elapses after a turn signal or brake operation by the driver is detected. The stepwise brake control starts from a final step of the two or more steps. <P>COPYRIGHT: (C)2007,JPO&INPIT

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

  The above-described automatic braking control device has already been put into practical use in passenger cars, but it must be solved when trying to use the same function 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, passenger and cargo safety must be ensured, and it seems that this is done by automatic braking control of passenger cars. 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 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, Although it is a device that assumes the situation where the braking operation is not performed at all due to the driver's dozing or looking aside, by utilizing the present invention device even in the situation where the brake operation is performed by the driver, It is characterized by reducing the damage caused by the collision by assisting the driver's braking operation.

  That is, the automatic braking control device of the present invention includes a control unit that automatically performs braking control without a driving operation based on a sensor output including a distance to an object in the traveling direction of the host vehicle. The predicted value of the time required for the object and the vehicle to be less than a predetermined distance derived based on the relative distance and the relative speed between the object and the vehicle obtained by the sensor output is a set value. Stepwise braking control means that automatically performs stepwise braking control when the pressure falls below the level, the stepwise braking control means gradually increases the braking force or braking deceleration over a plurality of stages in time series. An automatic braking control device including control means.

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

  Here, the feature of the present invention is that it is provided with normal operation detecting means for detecting the normal driving state of the driver, and when the normal driving detecting means detects the normal driving state of the driver, the number of steps Is provided with a means for reducing the above.

  This makes it possible to execute different automatic braking control in situations where the driver is asleep or looking aside and in situations where the driver is in a normal driving state and performing a collision avoidance operation until just before the collision. Therefore, even when the driver is performing a collision avoidance operation, the automatic braking control by the device of the present invention can be used effectively.

  The normal driving detection means may include means for determining that the driver is in a normal driving state until a predetermined time or more has elapsed from a detection time of a direction indicator or brake operation by the driver.

  Thus, it can be determined that the driver is in a normal driving state until a predetermined time or more elapses from the time when the operation of either or both of the direction indicator and the brake is detected.

  Further, the means for reducing may include means for starting automatic braking control from the final stage of the plurality of stages. In other words, if the driver is performing a collision avoidance operation, stepwise braking control is no longer necessary, so that the device of the present invention may start braking control from the final step.

  According to the present invention, it is possible to reduce damage caused by a collision by using automatic braking control in a truck or bus together with a collision avoidance operation by a driver. For example, even when a braking operation by the driver suddenly becomes difficult due to an unexpected situation, the vehicle speed can be surely reduced by the automatic 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 the operation of a braking control ECU (Electric Control Unit) of this embodiment. FIG. 3 is a diagram showing a braking pattern (at the time of idle product) that the braking control ECU has. FIG. 4 is a diagram showing a braking pattern (half-product time) that the braking control ECU has. FIG. 5 is a diagram showing a braking pattern (at the time of fixed volume) that the braking control ECU has. FIG. 6 is a diagram illustrating an example of a full-scale braking pattern possessed by the braking control ECU.

  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, and the EBS (Electric Breaking System) _ECU 10 are connected to each other via a VehicleCAN (J1939) 7.

  The steering sensor 2, the yaw rate sensor 3, and the vehicle speed sensor 13 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, A braking control ECU 4 that automatically performs braking control based on sensor outputs such as a yaw rate sensor 3 for detecting yaw rate and a vehicle speed sensor 13 for detecting own vehicle speed is provided. Stepwise braking automatically when TTC derived based on the relative distance and relative speed between the object and the vehicle obtained from sensor outputs from the wave radar 1 and the vehicle speed sensor 13 falls below a set value. Stepwise braking control means for performing control is provided, and this stepwise braking control means, as shown in FIG. 3 (b), is brake braking that gradually increases the braking force over three stages in time series. Including the means.

  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.

  In the example of FIG. 3B, first, braking of about 0.1 G is applied from TTC 2.4 seconds to 1.6 seconds in the first stage marked “alarm”. 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 0.5G) 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 braking operation of the driver acts as a brake instruction to the EBS (Electric Breaking System) _ECU 10, and the EBS_ECU 10 appropriately adjusts the braking force of the brake actuator 11 even if the driver should perform an excessive braking operation.

  As shown in FIGS. 3 to 5, the braking control ECU 4 includes a braking pattern selection unit 40 that changes the braking pattern according to the weight of the loaded cargo or the passenger. As a method of changing, the braking pattern storage unit 41 of the braking control ECU 4 stores in advance a plurality of control patterns for “empty product”, “half product”, and “constant product”, and the braking pattern selection unit 40. Can be realized by selecting a braking pattern that matches (or approximates) from 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.

  Here, the feature of this embodiment is that the braking control ECU 4 includes a normal operation detection unit 50 that detects the normal operation state of the driver, and the normal operation detection unit 50 detects the normal operation state of the driver. When it is, the number of steps is reduced.

  The normal operation detection unit 50 indicates that the driver is in a normal operation state until a predetermined time or more has elapsed from the detection time of the operation of the direction indicator or the brake by the driver based on the direction indicator operation information or the brake information. to decide. The predetermined time is, for example, 10 seconds.

  When the number of steps is reduced, as shown in FIG. 6, automatic braking control is started from “full-scale braking” in “alarm”, “enlarged area braking”, and “full-scale braking” shown in FIGS. To do.

  In addition, 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, there is provided means for prohibiting activation of the stepwise braking control means. 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. Further, if the steering angle is + 30 ° or more or −30 ° or less, this is during a lane change or a sharp curve traveling, so it is outside the application event of the stepwise braking control and restricts the start of the stepwise braking control. . In this case, a yaw rate may be used instead of the steering angle.

  In this embodiment, if the host vehicle speed before the start of braking control is less than 60 km / h and is 15 km / h (minimum speed at which the usefulness of automatic braking control (full-scale braking control) is recognized) or more, stepwise Although the braking control is not performed, only the full-scale braking control shown in FIGS. 3B to 5B is performed as shown in FIG. When only such full-scale braking control is performed, braking control equivalent to conventional automatic braking control used in passenger cars can be applied. Note that 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. FIG. 2 will be described by taking a braking pattern at the time of idle product (FIG. 3) as an example, but the procedure of the flowchart of FIG. 2 is also followed at the time of half product (FIG. 4) or constant product (FIG. 5). As shown in FIG. 2, the distance between the preceding vehicle and the vehicle speed of the preceding vehicle are measured and monitored 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 (S1). The braking pattern selection unit 40 of the braking control ECU 4 selects in advance one of the braking patterns (FIGS. 3 to 5) based on the measurement result of the weight. The following description is an example in which the braking pattern of FIG. 3 is selected.

TTC is calculated from the inter-vehicle distance, the own vehicle speed, and the vehicle speed of the preceding vehicle (S2). The calculation method is
Distance between vehicles / (Self-vehicle speed-Vehicle speed of the preceding vehicle)
It is. The host vehicle speed before starting the braking control is 60 km / h or more (S3), the steering angle before starting the braking control is +30 degrees or less and -30 degrees or more (S4), and the direction indicator or brake operation by the driver If a predetermined time (for example, 10 seconds) has elapsed from the time, the normal operation detection unit 50 of the braking control ECU 4 determines that the driver is in an abnormal operation state such as a snooze operation or a side-view operation (S5). If the TTC is in the region (1) shown in FIG. 3A (S6), "alarm" braking control is executed (S9). If the TTC is in the region (2) shown in FIG. 3A (S7), "enlarged region braking" control is executed (S10). If the TTC is in the region (3) shown in FIG. 3 (a) (S8), "full-scale braking" control is executed (S11). Further, if a predetermined time or more has not elapsed since the direction indicator or the brake operation time by the driver (S5), the normal operation detection unit 50 of the braking control ECU 4 can determine that the driver is in the normal operation state. In this case, when the TTC enters the region (3) shown in FIG. 3A (S8), the “full-scale braking” control is executed (S11).

  Further, if the vehicle speed before starting the braking control is less than 60 km / h and 15 km / h or more (S3, S12) and the TTC is in the region (4) shown in FIG. In contrast, the fact that the relative distance from the preceding vehicle is short is notified (S14). Notification is performed by warning display or buzzer sound. Further, if the TTC is in the region (5) shown in FIG. 3C (S15), "full-scale braking" control is executed (S11).

  Note that 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, FIGS. 3 to 5 will be described. The straight lines c, f, i in FIGS. 3 to 5 are called steering avoidance limit straight lines. Also, the curves B, D, and F in FIGS. 3 to 5 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. 3 to 5, 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. 3, the straight line c has TTC set to 0.8 seconds. In this embodiment, a straight line a when the TTC is 2.4 seconds is provided above the steering avoidance limit straight line c, and a straight line b when the TTC is 1.6 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 S2 of FIG. 2, a collision occurs at this time. However, in practice, since the host vehicle speed is reduced by the braking control, the actual TTC is longer than the calculation result of step S2.

  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 (about 0.5G) is applied from TTC 0.8 seconds to 0 seconds.

  FIG. 4 shows an example at half load, and FIG. 5 shows an example at constant load. However, when compared with equal braking forces, the braking distance increases as the weight of loaded cargo and passengers increases. The avoidance limit curve and the braking avoidance limit curve also move upward in the figure. Thereby, the area of area | region (1), (2), (3), (4), (5) becomes large according to the weight of a loaded cargo or a passenger.

  The straight lines a to c in FIG. 3 correspond to the straight lines df to f in FIG. 4 and the straight lines g to i in FIG. 5, and the curves A and B in FIG. 3 are the curves C and D in FIG. , F, and the black point G in FIG. 3 corresponds to the black point H in FIG. 4 and the black point I in FIG.

  According to the present invention, automatic braking control in trucks and buses can be used in combination with a collision avoidance operation by a driver, which can contribute to traffic safety.

The control system block diagram of a present Example. The flowchart which shows operation | movement of braking control ECU of a present Example. The figure which shows the braking pattern (at the time of an empty product) which braking control ECU has. The figure which shows the braking control pattern (at the time of half product) which braking control ECU has. The figure which shows the braking pattern (at the time of 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
8 Engine ECU
9 Shaft weigher 10 EBS_ECU
11 Brake Actuator 12 Engine 13 Vehicle Speed Sensor 40 Brake Pattern Selection Unit 41 Brake Pattern Storage Unit 50 Normal Operation Detection Unit

Claims (3)

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 predicts the time required for the object and the vehicle, which are derived based on the relative distance and relative speed between the object and the vehicle obtained from the sensor output, to be equal to or less than a predetermined distance. Stepwise braking control means for automatically performing stepwise braking control when the value falls below the set value,
The stepwise braking control means is an automatic braking control device including a braking control means for gradually increasing a braking force or a braking deceleration over a plurality of stages in a time series,
Provided with a normal driving detection means for detecting the normal driving state of the driver,
An automatic braking control device comprising: means for reducing the number of steps when the normal driving detecting means detects a normal driving state of the driver.   The said normal driving | running detection means is provided with the means to judge that the said driver | operator is in a normal driving | running state until more than predetermined time passes from the detection time of operation of a direction indicator or a brake by a driver | operator. The automatic braking control device described.   The automatic braking control device according to claim 1, wherein the reducing means includes means for starting automatic braking control from a final stage of the plurality of stages.

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