JP4790522B2 - 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

  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 includes a control unit that automatically performs braking control based on a sensor output including a distance to an object in the traveling direction of the host vehicle without a driving operation, and the control unit is obtained from the sensor output. When the predicted value of the time required for the object and the vehicle to be within a predetermined distance or less derived based on the relative distance and relative speed between the object and the vehicle is less than a set value, This is an automatic braking control device provided with stepwise braking control means for performing stepwise braking control.

  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, a feature of the present invention is that the stepwise braking control means includes braking control means for gradually increasing the braking force over a plurality of stages in time series, and the braking control means There is a means for changing the braking pattern accordingly.

  In other words, when the distance to the object is sufficient and the TTC can be calculated as a time with a margin, the braking control gradually increases the braking force over a plurality of stages as originally planned. It can be performed. Thereby, braking control suitable for large vehicles such as trucks and buses can be performed.

  However, the object suddenly jumps out in front of the vehicle, or the radar that measures the distance between the preceding vehicle cannot detect the preceding vehicle until just before due to the special shape of the preceding vehicle, or the preceding vehicle In situations where the vehicle is traveling in a place that is biased to the left or right rather than in the middle of the lane, and the radar detects the preceding vehicle again and then detects it immediately before the preceding vehicle, the TTC is also the original plan. In some cases, the time may be much shorter than that. According to the present invention, it is possible to appropriately cope with such a situation.

  The means for changing the braking pattern can correspond to any TTC by providing means for reducing the number of stages of braking control in the original plan according to the TTC.

  Furthermore, the means for reducing the number of stages includes means for changing the shape of the braking pattern applied when the number of stages is not reduced to a new braking pattern shape corresponding to the number of stages to be reduced. Can do.

  According to this, more effective braking control can be realized as compared with a case where the number of steps is simply reduced.

  Alternatively, the means for changing the braking pattern may include means for changing the shape of the braking pattern without reducing the number of steps. According to this, a sudden change in the braking pattern can be avoided, and the stability of the vehicle can be kept high.

  According to the present invention, automatic braking control in a truck or bus can be realized. In particular, appropriate braking control can be performed even when the TTC is very short.

  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 flowchart showing an operation procedure of a braking pattern at the time of idle. FIG. 4 is a diagram showing a braking pattern at the time of the idle control that the braking control ECU has.

  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 a value derived based on the relative distance and relative speed between the object and the vehicle obtained by sensor outputs from the wave radar 1 and the vehicle speed sensor 13 falls below a set value. It is an automatic braking control device provided with stepwise braking control means for performing control.

  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.

  Here, the present embodiment is characterized in that the stepwise braking control means includes braking control means for gradually increasing the braking force over three stages in time series as shown in FIG. The control means is provided with means for changing the braking pattern in accordance with TTC.

  5 to 8 are diagrams for explaining the braking patterns # 1 to # 4 corresponding to the TTC, respectively, but this braking control means further reduces the number of steps in order to change the braking pattern. The shape of the braking pattern (for example, FIG. 4) applied when the number of steps is not reduced is changed to the shape of new braking patterns # 3 and # 4 corresponding to the number of steps to be reduced as shown in FIGS. Change to Further, like the braking patterns # 1 and # 2 shown in FIGS. 5 and 6, it is possible to change only the braking pattern shape without reducing the number of steps.

  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. 4 (b), first, braking of about 0.1G 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.

  FIG. 9 is a diagram showing a braking pattern at the time of half product possessed by the braking control ECU 4, and FIG. 10 is a diagram showing a braking pattern at the constant product possessed by the braking control ECU 4, but FIG. As shown in FIG. 10, 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 passengers. 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.

  Further, the means for changing to the shape of the new braking patterns # 1 to # 4 are also shown in FIG. 4 (at the time of empty product), FIG. 9 (at the time of half product), and FIG. 10 (at the time of constant product). A plurality of corresponding braking patterns # 1 to # 4 are stored in the braking pattern storage unit 41 in advance, and the braking pattern selection unit 40 selects a braking pattern adapted (or approximated) from these braking patterns according to the value of TTC. By selecting, the braking patterns shown in FIGS. 4, 9, and 10 can be changed to braking patterns # 1 to # 4, respectively.

  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 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, as shown in FIG. 11, only the full braking control shown in FIGS. 4B, 9B, and 10B 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. 2 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. 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 one of the braking patterns (FIGS. 4, 9, and 10) in advance based on the measurement result of the weight. The following description is an example in which the braking pattern of FIG. 4 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. When the host vehicle speed before starting the braking control is 60 km / h or more (S3), and the steering angle before starting the braking control is +30 degrees or less and -30 degrees or more (S4), the calculation is performed in step S2. When the TTC value is larger than the threshold value # 1 (S5), the braking pattern # 1 shown in FIG. 5 is selected. The shape of the braking pattern # 1 is the same as the shape of the braking pattern shown in FIG. Therefore, the threshold value # 1 is 2.4 seconds in the example of FIG.

  If the TTC value calculated in step S2 is greater than threshold value # 2 and equal to or less than threshold value # 1 (S6), braking pattern # 2 shown in FIG. 6 is selected. The shape of the braking pattern # 2 is obtained by changing the shape of the braking pattern shown in FIG. The shape of the braking pattern before the change is indicated by a broken line. Although the three-step braking pattern is maintained, the braking pattern is shortened in the area of alarm and extended area braking. The threshold value # 2 is set around 1.6 seconds in the example of FIG. Thereby, compared with the case where the number of steps is reduced, the change of the braking pattern becomes gradual, and the stability of the vehicle can be kept high.

  If the TTC value calculated in step S2 is greater than threshold value # 3 and less than or equal to threshold value # 2 (S7), braking pattern # 3 shown in FIG. 7 is selected. The shape of the braking pattern # 3 is obtained by changing the shape of the braking pattern shown in FIG. The shape of the braking pattern before the change is indicated by a broken line. Compared with the shape of the braking pattern shown in FIG. 4B, there is no enlarged area braking, and full-scale braking starts immediately after the alarm. The threshold value # 3 is set around 0.8 seconds in the example of FIG.

  If the TTC value calculated in step S2 is equal to or less than the threshold value # 3 (S8), the braking pattern # 4 shown in FIG. 8 is selected. The shape of the braking pattern # 4 is obtained by changing the shape of the braking pattern shown in FIG. The shape of the braking pattern before the change is indicated by a broken line. Compared with the shape of the braking pattern shown in FIG.

  In this way, stepwise braking control is performed as much as possible according to the value of TTC, but sudden braking may be suddenly performed when the value of TTC is extremely small. Thereby, appropriate automatic braking control can be performed according to the value of TTC.

  Further, if the host vehicle speed before starting the braking control is less than 60 km / h and 15 km / h or more (S3, S13) 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 (S15). Notification is performed by warning display or buzzer sound. Further, if the TTC is in the region (5) shown in FIG. 4C (S16), "full-scale braking" control is executed (S17).

  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.

  Further, as shown in FIG. 3, in the braking pattern shown in FIG. 4, if the TTC is in the region (1) shown in FIG. 4A (S21), “alarm” braking control is executed (S24). . If the TTC is in the region (2) shown in FIG. 4A (S22), "enlarged region braking" control is executed (S25). Further, if the TTC is in the region (3) shown in FIG. 4A (S23), "full-scale braking" control is executed (S26). The same applies to the braking patterns shown in FIGS. 9 and 10.

  Here, FIG. 4, FIG. 9, and FIG. 10 will be described. The straight lines c, f, and i in FIGS. 4, 9, and 10 are called steering avoidance limit straight lines. Further, curves B, D, and F in FIGS. 4, 9, and 10 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.

  4, 9, and 10, a collision can no longer be avoided by a steering operation or a braking operation in an area where both of the lower sides of these straight lines or curves are involved.

  For example, in the example of the empty product in FIG. 4, 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. 9 shows an example at half load, and FIG. 10 shows an example at fixed load. However, when equal braking forces are used, 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.

  4 correspond to the straight lines d to f in FIG. 9 and the straight lines g to i in FIG. 10, and the curves A and B in FIG. 4 are the curves C and D in FIG. 9 and the curve E in FIG. , F, and the black point G in FIG. 4 corresponds to the black point H in FIG. 9 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, since appropriate braking control can be performed even when the TTC is very short, a wide range of unexpected situations can be dealt with.

The control system block diagram of a present Example. The flowchart which shows operation | movement of braking control ECU of a present Example. The flowchart which shows the operation | movement procedure of the braking pattern at the time of an empty product. The figure which shows the braking pattern at the time of the idle product which braking control ECU has. The figure for demonstrating braking pattern # 1. The figure for demonstrating braking pattern # 2. The figure for demonstrating braking pattern # 3. The figure for demonstrating braking pattern # 4. 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 (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 estimated time calculated when the object is detected for the first time or when the object is lost and detected again is the time limit for avoiding the collision by the braking operation or the limit for avoiding the collision by the steering operation If it was shorter than the time period, the automatic brake control device characterized by comprising means for changing the braking pattern.   2. The automatic braking control device according to claim 1, wherein the means for changing the braking pattern includes means for reducing the number of the steps.   The means for reducing the number of steps is a means for changing the shape of the braking pattern applied when the number of braking steps of the three steps is not reduced to a shape of a new braking pattern according to the number of steps to be reduced. 3. The automatic braking control device according to claim 2, further comprising: 2. The automatic braking control device according to claim 1, wherein the means for changing the braking pattern includes means for changing the shape of the braking pattern without reducing the number of steps.

Images