JP2007084046A - Automatic brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve an automatic brake control in a truck or a bus. <P>SOLUTION: A stepwise brake control is automatically performed when TTC obtained according to a relative distance and a relative speed between the own vehicle and an object is lower than a predetermined value. For example, a brake force or a brake reduction speed is gradually increased over a plurality of stages in time series. Moreover, the starting of the stepwise brake control is prohibited when a vehicle speed is not more than a predetermined value, and the value of a steering angle or a yaw rate is outside the predetermined range. <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 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. Is provided with stepwise braking control means for automatically performing stepwise braking control when the predicted value of the time required until the distance falls below the predetermined distance falls below the set value.

  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)).

  The stepwise braking control means includes, for example, braking control means for gradually increasing the braking force or the braking deceleration over a plurality of stages in time series.

  Thus, instead of using the maximum braking force or braking deceleration suddenly, gradually increasing the braking force or braking deceleration gradually, the braking normally performed by the driver of the truck or bus Since the braking pattern can be close to the pattern, the vehicle speed can be reduced while maintaining the stability of the vehicle.

  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.

  In other words, the stepwise braking control performed by the automatic braking control device of the present invention is such that, for example, 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.

  An automatic braking control apparatus according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of the automatic braking control device of this 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 loading that the braking control ECU has. FIG. 4 is a diagram showing a braking pattern at the time of half product of the braking control ECU. FIG. 5 is a diagram showing a braking pattern at the time of fixed volume possessed by the braking control ECU. FIG. 6 is a diagram showing 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, 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. .

  Here, the feature of the present embodiment is that the braking control ECU 4 is based on the relative distance and relative speed between the object and the vehicle obtained by sensor outputs from the millimeter wave radar 1 and the vehicle speed sensor 13. There is a stepwise braking control means for automatically performing stepwise braking control when the derived TTC falls below a set value.

  As shown in FIG. 3B, this stepwise braking control means includes braking control means for gradually increasing the braking force over three stages in time series. 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 0.5 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 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.

  In the present embodiment, 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.

  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 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 the present embodiment is such that 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 sharply 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 before starting the braking control is +30 degrees or more or −30 degrees or less, this is during lane change or sharp curve traveling, so it is outside the staged braking control application event and staged braking control. Restrict startup of. In this case, a yaw rate may be used instead of the steering angle.

  In this embodiment, when 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 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. 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 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 TTC is shown in FIG. If it is in the area (1) (S5), "alarm" braking control is executed (S8). If the TTC is in the region (2) shown in FIG. 3A (S6), "enlarged region braking" control is executed (S9). If the TTC is in the region (3) shown in FIG. 3 (a) (S7), "full-scale braking" control is executed (S10).

  Further, if the vehicle speed before starting the braking control is less than 60 km / h and 15 km / h or more (S3, S11) 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 (S13). Notification is performed by warning display or buzzer sound. Further, if the TTC is in the region (5) shown in FIG. 3C (S14), "full-scale braking" control is executed (S10).

  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 case 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 (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 fixed load. However, when compared with equal braking forces, the braking distance increases as the weight of loaded cargo and passengers increases. The steering avoidance limit curve 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.

  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.

  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.

The block block diagram of the automatic braking control apparatus of a present Example. The flowchart which shows operation | movement of braking control ECU of this invention 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
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

Claims (3)

In an automatic braking control device including 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,
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. An automatic braking control device comprising stepwise braking control means for automatically performing stepwise braking control when a value falls below a set value.   2. The automatic braking control device according to claim 1, wherein the stepwise braking control means includes braking control means for gradually increasing a braking force or a braking deceleration over a plurality of stages in time series.   2. The automatic braking control device according to claim 1, further comprising means for prohibiting the stepwise braking control means from starting 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.

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