JP2013212772A - Automatic braking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic braking device capable of preventing brake control at unnecessary strength when a locked wheel is released.SOLUTION: In an automatic braking device 100, even when a wheel is locked and a vehicle speed of zero is estimated, deviation between target deceleration and actual deceleration is not accumulated during a period in which the wheel is locked. Accordingly, unnecessarily large feedback deceleration and instruction deceleration are prevented from being calculated. As a result, when the lock of the wheel is released, the brake control at unnecessarily large magnitude is prevented.

Description

  The present invention relates to an automatic braking device that controls the strength of a brake so as to reduce a deviation between a target deceleration and an actual deceleration.

  As a conventional technique in the above technical field, a braking / driving force control device described in Patent Document 1 is known. The braking / driving force control device described in Patent Document 1 includes a means for acquiring a target deceleration to be generated in the entire vehicle, a means for acquiring an actual deceleration generated in the entire vehicle, a target deceleration and an actual deceleration. Means for accumulating the deviation from the deceleration, and performs feedback control so as to reduce the accumulation of deviation between the target deceleration and the actual deceleration.

JP 2008-55994 A

  Incidentally, the actual deceleration may be estimated based on the vehicle speed obtained from the rotational speed of the wheel of the host vehicle. In such a case, when the wheel of the host vehicle is locked, the actual deceleration may be estimated to be zero even though the host vehicle is actually decelerating. Then, since the deviation between the target deceleration and the actual deceleration increases, the accumulated deviation is also calculated greatly. As a result, the brake strength is feedback-controlled to reduce the accumulation of deviations calculated to be larger than the actual, and when the vehicle's wheels are unlocked, the braking force of unnecessary strength is controlled. Control may occur.

  This invention is made in view of such a situation, and it is a subject to provide the automatic braking device which can suppress that the control of the brake by unnecessary strength arises at the time of cancellation | release of the lock | rock of a wheel. To do.

  In order to solve the above problems, an automatic braking apparatus according to the present invention is estimated from target deceleration calculation means for calculating a target deceleration indicating a target deceleration of the host vehicle, and the rotational speed of the wheels of the host vehicle. The actual deceleration estimating means for estimating the actual deceleration indicating the actual deceleration of the own vehicle based on the vehicle speed of the own vehicle, the target deceleration calculated by the target deceleration calculating means, and the actual deceleration estimating means A cumulative deviation calculating means for calculating the cumulative deviation by accumulating the deviation from the estimated actual deceleration; a brake control means for controlling the strength of the brake so as to reduce the cumulative deviation calculated by the cumulative deviation calculating means; The accumulated deviation calculating means interrupts accumulation of the deviation between the target deceleration and the actual deceleration during a period in which the wheels of the host vehicle are locked.

  In this automatic braking device, the target deceleration is calculated, and the actual deceleration is estimated based on the vehicle speed estimated from the rotational speed of the wheels. Then, the accumulated deviation is calculated by accumulating the deviation between the target deceleration and the actual deceleration, and the brake strength is controlled so as to reduce the accumulated deviation. In particular, in this automatic braking device, accumulation of the deviation between the target deceleration and the actual deceleration is interrupted during a period in which the wheels are locked. For this reason, it can be avoided that the accumulated deviation is calculated to be larger than the actual deviation due to the fact that the actual deceleration is estimated to be 0 due to the locking of the wheel. Therefore, according to this automatic braking device, it is possible to suppress the occurrence of brake control with unnecessary strength when the wheel lock is released.

  In the automatic braking device according to the present invention, the cumulative deviation calculating means may hold the cumulative deviation calculated and accumulated before the period during the period in which the wheels of the host vehicle are locked. it can. In this way, it is possible to reliably prevent the cumulative deviation between the target deceleration and the actual deceleration from being calculated larger than actual due to the locking of the wheels.

  In the automatic braking device according to the present invention, the target deceleration can be a deceleration necessary for urgently avoiding a collision between the host vehicle and an obstacle. When the collision with an obstacle is urgently avoided, the target deceleration becomes relatively large, so that the increase in cumulative deviation due to the estimated realization speed being zero due to wheel locking may become significant. is there. Therefore, the effect of interrupting the accumulation of the deviation between the target deceleration and the actual deceleration during the period when the wheel is locked is further increased.

  It is possible to provide an automatic braking device capable of suppressing the occurrence of brake control with unnecessary strength when the wheel is unlocked.

1 is a block diagram showing a schematic configuration of an embodiment of an automatic braking device according to the present invention. It is a schematic diagram for demonstrating the feedback control of the feedback control unit shown by FIG. It is a graph which shows a mode that the deviation of target deceleration and actual deceleration is accumulated in the period when a wheel is locked. 3 is a flowchart showing an example of an operation for calculating a cumulative deviation of the feedback control unit shown in FIG. 1. It is a graph which shows a mode that accumulation of the deviation of a target deceleration and an actual deceleration is avoided in the period when the wheel is locked.

  Hereinafter, an embodiment of an automatic braking device according to the present invention will be described in detail with reference to the drawings. In the following description of the drawings, the same elements or corresponding elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a block diagram showing a schematic configuration of an embodiment of an automatic braking device according to the present invention. In this embodiment, the automatic braking device according to the present invention is applied to a system (for example, a pre-crash safety system) for a pre-crash brake (hereinafter referred to as “PB”).

  As shown in FIG. 1, the automatic braking device 100 includes a PB command unit (target deceleration calculation means) 10, a vehicle speed sensor 20, a feedback control unit (actual deceleration estimation means, cumulative deviation calculation means) 30, and brake control. A unit (brake control means) 40 is provided. Such an automatic braking device 100 is mounted on a vehicle. Hereinafter, a vehicle equipped with the automatic braking device 100 is referred to as “own vehicle”.

  The PB command unit 10 includes, for example, a sensor for monitoring the front of the host vehicle. For example, when the possibility of collision between the host vehicle and an obstacle such as a pedestrian or another vehicle increases, the PB command unit 10 assists in avoiding the collision or assists in reducing damage in the collision. Instruct to slow down. Therefore, the PB command unit 10 calculates a target deceleration indicating a target deceleration of the host vehicle. Then, the PB command unit 10 outputs information indicating the calculated target deceleration to the feedback control unit 30.

The target deceleration changes depending on the likelihood of collision between the host vehicle and the obstacle and the estimated time until the host vehicle collides with the obstacle. If the deceleration is necessary for emergency avoidance, it is a relatively large value of about 8 m / s ² , for example.

  The vehicle speed sensor 20 is, for example, a sensor that estimates the vehicle speed of the host vehicle from the rotational speed of the wheels of the host vehicle. The vehicle speed sensor 20 outputs information indicating the estimated vehicle speed of the host vehicle to the feedback control unit 30.

  The feedback control unit 30 estimates the actual deceleration indicating the actual deceleration of the host vehicle based on the change amount of the host vehicle speed input from the vehicle speed sensor 20. Further, the feedback control unit 30 acquires (calculates) a cumulative deviation by accumulating the deviation between the target deceleration input from the PB command unit 10 and the estimated actual deceleration.

  Further, the feedback control unit 30 outputs information indicating the command deceleration necessary for reducing the acquired cumulative deviation to the brake control unit 40. The brake control unit 40 controls the strength of the brake according to the command deceleration from the feedback control unit 30. Such feedback control will be specifically described with reference to FIG.

  As shown in FIG. 2, the feedback control unit 30 calculates a deviation by subtracting the actual speed from the target deceleration input from the PB command unit 10 and accumulates the calculated deviation to obtain a cumulative deviation. . For accumulation of the deviation, integration is generally used, but another calculation method in accordance with the brake characteristics of the host vehicle may be used. Then, the feedback control unit 30 calculates a command deceleration by adding a feedback deceleration obtained by multiplying the acquired accumulated deviation by a predetermined gain and a feedforward deceleration (target deceleration).

  By performing the feedback control as described above, for example, when the deviation accumulates with a positive value, that is, when the actual deceleration is smaller than the target deceleration, the feedback deceleration increases in the positive direction and the command decreases. Since the speed increases, the brake strength is controlled by the brake control unit 40 so that the actual deceleration approaches the target deceleration.

  On the other hand, if the deviation is accumulated with a negative value, that is, if the actual deceleration is larger than the target deceleration, the feedback deceleration decreases in the negative direction and the command deceleration decreases. The brake strength is controlled so that the realized speed approaches the target deceleration. That is, in any case, the brake control unit 40 controls the strength of the brake so that the target deceleration and the actual deceleration approach each other, that is, the cumulative deviation between the target deceleration and the actual speed is reduced. Will be.

  By the way, on some bad roads such as low μ roads, gravel roads, and snowy roads, the wheels of the host vehicle may be locked. In that case, since the rotational speed of the wheel of the host vehicle is 0 during the period in which the wheel is locked, the vehicle speed of the host vehicle is also the actual vehicle speed as shown by the solid line in FIG. Regardless of (broken line in the figure), the vehicle speed sensor 20 estimates zero.

  Therefore, as indicated by a broken line in FIG. 3B, the actual deceleration is also estimated to be 0 by the feedback control unit 30 during the period in which the wheel is locked. Therefore, during the period in which the wheels are locked, the deviation between the target deceleration and the actual speed becomes large, so that the accumulated deviation is greatly calculated by the feedback control unit 30.

  As a result, the feedback deceleration increases as shown in FIG. 2, and the command deceleration output to the brake control unit 40 also increases. As a result, when the wheel lock is released, that is, when the host vehicle recovers from the wheel lock, the brake control unit 40 controls the brake with an unnecessary strength. In that case, an unnecessarily large deceleration occurs, which may give anxiety to the following vehicle, for example.

  The automatic braking device 100 has a configuration for avoiding such a situation. That is, in the automatic braking device 100, the brake control unit 40 interrupts the accumulation of the deviation between the target deceleration and the actual deceleration during the period in which the wheels of the host vehicle are locked. More specifically, the brake control unit 40 holds the accumulated deviation that is accumulated and calculated before that period during the period in which the wheels of the host vehicle are locked.

  As a result, it can be avoided that the cumulative deviation is calculated to be larger than the actual deviation due to the difference between the actual deceleration and the target deceleration due to wheel locking. Therefore, when the wheel is unlocked, it is possible to suppress the brake control with an unnecessary strength with the command deceleration corresponding to the accumulated deviation calculated to be larger than the actual, and consequently to the following vehicle. And avoiding anxiety.

  The PB command unit 10, the feedback control unit 30, and the brake control unit 40 are mainly composed of a computer including a CPU, a ROM, a RAM, and the like. Each operation of the PB command unit 10, the feedback control unit 30, and the brake control unit 40 is realized by executing a predetermined program in the computer.

  Subsequently, an operation related to calculation of the cumulative deviation of the feedback control unit 30 in the automatic braking apparatus 100 according to the present embodiment will be described. FIG. 4 is a flowchart showing an example of an operation for calculating the cumulative deviation of the feedback control unit shown in FIG. As shown in FIG. 4, first, the feedback control unit 30 determines whether or not the vehicle speed of the host vehicle input from the vehicle speed sensor 20 is 0, that is, whether or not the wheels of the host vehicle are locked. Is performed (step S101).

  When the result of the determination in step S101 is a result indicating that the vehicle speed of the host vehicle is not 0, that is, a result indicating that the wheels of the host vehicle are not locked, the feedback control unit 30 performs the target reduction. The accumulated deviation is calculated by accumulating the deviation between the speed and the actual deceleration (step S102). In addition, as described above, integration is generally used for accumulation of deviations, but other calculation methods in accordance with the brake characteristics of the host vehicle may be used. Thereafter, the current process is terminated, and the determination in step S101 is performed again at a predetermined time interval.

  On the other hand, when the result of the determination in step S101 is a result indicating that the vehicle speed of the host vehicle is 0, that is, the wheels of the host vehicle are locked (or the host vehicle is already stopped). ), The feedback control unit 30 interrupts the accumulation of the deviation between the target deceleration and the actual deceleration, and fixes (holds) the accumulated deviation calculated up to the previous time (step S103). . Thereafter, the current process is terminated, and the determination in step S101 is performed again at a predetermined time interval.

  As described above, in the automatic braking device 100, even if the wheels are locked and the vehicle speed is estimated to be 0 as shown in FIG. 5A, as shown in FIG. Since the deviation between the target deceleration and the actual deceleration is not accumulated during the period in which the wheel is locked, it is possible to prevent the feedback deceleration and the command deceleration from being calculated more than necessary.

  As a result, according to the automatic braking apparatus 100, when the lock of the wheel of the host vehicle is released, the brake control with an unnecessary size is suppressed. That is, according to the automatic braking device 100, it is possible to avoid an unnecessarily large deceleration from occurring, and thus to avoid giving anxiety to the following vehicle.

  The above embodiment describes one embodiment of the automatic braking device according to the present invention. Therefore, the automatic braking device according to the present invention is not limited to the automatic braking device 100 described above. The automatic braking device according to the present invention can be arbitrarily modified from the automatic braking device 100 described above without departing from the scope of the claims recited in the claims.

  For example, in the above-described embodiment, the automatic braking device according to the present invention is applied to a system for PB. However, the automatic braking device according to the present invention is not limited to such a system, and is applied to any system. be able to.

  DESCRIPTION OF SYMBOLS 10 ... PB command unit (target deceleration calculation means), 30 ... Feedback control unit (actual deceleration estimation means, cumulative deviation calculation means), 40 ... Brake control unit (brake control means), 100 ... Automatic braking device

Claims (3)

Target deceleration calculating means for calculating a target deceleration indicating a target deceleration of the host vehicle;
Actual deceleration estimation means for estimating an actual deceleration indicating an actual deceleration of the host vehicle based on a vehicle speed of the host vehicle estimated from a rotation speed of a wheel of the host vehicle;
A cumulative deviation calculating means for calculating a cumulative deviation by accumulating a deviation between the target deceleration calculated by the target deceleration calculating means and the actual deceleration estimated by the actual deceleration estimating means;
Brake control means for controlling the strength of the brake so as to reduce the cumulative deviation calculated by the cumulative deviation calculation means,
The automatic deviation device, wherein the cumulative deviation calculation means interrupts the accumulation of deviations between the target deceleration and the actual deceleration during a period in which the wheels of the host vehicle are locked.   2. The accumulated deviation calculation unit holds the accumulated deviation calculated and accumulated before the period during a period in which the wheels of the host vehicle are locked. Automatic braking device.   The automatic braking apparatus according to claim 1, wherein the target deceleration is a deceleration necessary for urgently avoiding a collision between the host vehicle and an obstacle.

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