Vehicle Braking Control System

Abstract

To provide a vehicle brake control system capable of reducing electric power consumption compared to conventional systems.SOLUTION: A control device 40 executes control to increase brake force of a wheel on a roadside at a stop position relative to that on a wheel on an opposite side, when both conditions, that a distance from the stop position to a vehicle position is determined to be equal to or shorter than a predetermined distance on the basis of information from a position information acquisition section 20 and vehicle stop operation to stop a vehicle at the roadside of the stop position is determined to be performed on the basis of information from a vehicle operation acquisition section 30, are met. Thus, a difference in brake force enables a vehicle to turn toward the roadside without relying on steering operation. Therefore, the control device can control the vehicle while reducing electric power steering motor force and thereby reducing electric power consumption compared to a case where control to reduce power steering motor force is not executed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a braking control system for a public vehicle such as a bus. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2006-224706 discloses a technology that detects the driver's steering assistance request from the load applied by the driver to the steering wheel, and generates an inward yaw moment by generating a difference in the braking force between the left and right wheels in accordance with the steering assistance request.

[0003] However, the technology disclosed in the above publication has the following problems. It is desirable to reduce the power consumption of electric vehicles while they are running. However, the above publication does not mention anything about reducing power consumption. Therefore, there is room for improvement in reducing power consumption when buses and other public transport vehicles that frequently stop on the shoulder of the road stop on the shoulder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-224706 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a vehicle braking control system that can reduce power consumption compared to conventional systems. [Means for solving the problem]

[0006] The present invention that achieves the above object is as follows. (1) a location information acquisition unit that acquires vehicle location information; a vehicle behavior acquisition unit that acquires information on vehicle behavior for pulling over to the shoulder of a road at a predetermined stopping position; a control device that controls braking forces of left and right wheels based on information from the position information acquisition unit and the vehicle behavior acquisition unit; and The control device, when both of the following conditions are satisfied: it determines from information from the position information acquisition unit that the distance between the stopping position and the vehicle position is less than a predetermined distance; and it determines from information from the vehicle behavior acquisition unit that a stopping action is being taken to pull over to the shoulder of the road at the stopping position and stop the vehicle. This is a vehicle braking control system that controls the braking force of the wheels on the shoulder side of the stopping position to be stronger than the braking force of the wheels on the opposite side. (2) The control device further performs control to weaken the power steering motor force when both of the following conditions are satisfied: determining from the information of the position information acquisition unit that the distance between the stopping position and the vehicle position is less than a predetermined distance; and determining from the information of the vehicle behavior acquisition unit that a stopping action is being taken to pull over to the shoulder of the road at the stopping position. This is a braking control system for a vehicle described in (1). (3) The vehicle behavior acquisition unit acquires three pieces of information: information on blinker operation, information on brake operation, and information on steering operation; The control device determines that a stopping action is being taken to pull over to the shoulder of the stopping position when, based on information from the vehicle behavior acquisition unit, it determines that a turn signal is being operated toward the shoulder of the stopping position, that a brake is being operated, and that the steering operation direction is toward the shoulder of the stopping position. (1) A braking control system for a vehicle as described in (1). (4) A braking control system for a vehicle described in (3), wherein the control device maintains the control of making the braking force of the wheels on the shoulder side of the stopping position stronger than the braking force of the wheels on the opposite side when, while implementing control to make the braking force of the wheels on the shoulder side of the stopping position stronger than the braking force of the wheels on the opposite side, the control device determines, based on information from the vehicle behavior acquisition unit, that only the brake operation of the three pieces of information has begun to be released. [Effects of the Invention]

[0007] According to the vehicle braking control system of (1) and (2) above, when both of the following conditions are satisfied: the control device determines from information from the position information acquisition unit that the distance between the stopping position and the vehicle position is equal to or shorter than a predetermined distance, and determines from information from the vehicle behavior acquisition unit that a stopping action is being taken to pull over to the shoulder of the road at the stopping position, the control device performs control to strengthen the braking force of the wheels on the shoulder side of the stopping position more than the braking force of the wheels on the opposite side, allowing the vehicle to turn toward the shoulder due to the braking force difference without steering operation. Therefore, control to weaken the electric power steering motor force can be performed, and power consumption can be reduced compared to when control to weaken the power steering motor force is not performed.

[0008] According to the vehicle braking control system of (3) above, when the control device determines, based on information from the vehicle behavior acquisition unit, that a turn signal has been operated toward the shoulder of the stopping position, that a brake operation has been performed, and that the steering operation direction is toward the shoulder of the stopping position, it determines that a stopping action is being taken to pull over to the shoulder of the stopping position and stop the vehicle.Therefore, it can determine that a stopping action is being taken based on three pieces of information, thereby improving the accuracy of the determination.

[0009] According to the vehicle braking control system of (4) above, if the control device determines based on information from the vehicle behavior acquisition unit that only the brake operation of the three pieces of information has begun to be released while the control device is implementing control to make the braking force of the wheels on the shoulder side of the stopping position stronger than the braking force of the wheels on the opposite side, the control device maintains the control to make the braking force of the wheels on the shoulder side of the stopping position stronger than the braking force of the wheels on the opposite side, so that even if the brake operation is released while the control device is implementing control to make the braking force of the wheels on the shoulder side of the stopping position stronger than the braking force of the wheels on the opposite side, it is possible to prevent the vehicle's driving direction from suddenly changing even though the steering angle is not changed. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram of a vehicle braking control system according to an embodiment of the present invention; [Figure 2]3 is a flowchart showing an example of a control routine of a control device in the vehicle braking control system according to the embodiment of the present invention. [Figure 3] 1 is a flowchart illustrating an example of a control routine performed by a control device in a vehicle braking control system according to an embodiment of the present invention, during the execution of control to make the braking force of wheels on the shoulder side of a stopped position stronger than the braking force of wheels on the opposite side. [Figure 4] 1A and 1B are schematic diagrams illustrating how the vehicle braking control system maintains the difference in braking force between the left and right wheels when only the brake operation is released during control to make the braking force of the wheel on the shoulder side of the vehicle stopped position stronger than the braking force of the wheel on the opposite side of the vehicle, in accordance with an embodiment of the present invention. FIG. 1A shows the state during control to make the braking force of the wheel on the shoulder side of the vehicle stopped position stronger than the braking force of the wheel on the opposite side of the vehicle (when the brake operation is not released), and FIG. 1B shows the state when the brake operation is released. DETAILED DESCRIPTION OF THE INVENTION

[0011] A vehicle braking control system (hereinafter simply referred to as a system) 10 according to an embodiment of the present invention will be described below with reference to the drawings. The system 10 may also be referred to as a vehicle braking control device.

[0012] The system 10 is applied to electric vehicles, such as buses, etc. The system 10 includes a location information acquisition unit 20, a vehicle behavior acquisition unit 30, and a control device 40, as shown in FIG.

[0013] The position information acquisition unit 20 acquires vehicle position information, and acquires current vehicle position estimation information using, for example, a GPS (Global Positioning System).

[0014] The vehicle behavior acquisition unit 30 acquires information on vehicle behavior for pulling over to the shoulder of the road (on the left side in Japan) at a predetermined stopping location such as a bus stop. The vehicle behavior acquisition unit 30 acquires three pieces of information: information on turn signal operation, information on brake operation, and information on steering operation. That is, the vehicle behavior acquisition unit 30 has a turn signal operation acquisition unit 31 that acquires information on turn signal operation, a brake operation acquisition unit 32 that acquires information on brake operation, and a steering operation acquisition unit 33 that acquires information on steering operation.

[0015] The turn signal operation acquisition unit 31 can detect whether or not a turn signal is being operated and the direction of the turn signal based on the turn signal operation performed by the driver. The brake operation acquisition unit 32 can detect whether or not the brake is ON based on the brake pedal depression operation performed by the driver. The type of brake is not particularly limited, and may be a disc brake or a drum brake. The steering operation acquisition unit 33 can detect the steering direction based on the steering angle of the steering wheel performed by the driver, etc.

[0016] The control device 40 controls the braking force of the left and right wheels of the vehicle based on information (electrical signals) from the position information acquisition unit 20 and the vehicle behavior acquisition unit 30. The control device 40 performs control to create a difference in braking force between the left and right wheels, thereby generating yaw (a force that rotates the vehicle). Note that a similar technology is also used in technologies such as brake LDA (lane departure alert), which generates yaw by applying a difference in braking force to the left and right wheels to suppress lane departure and support the avoidance of lane / road departure.

[0017] The control device 40 has a stop position approach determination unit 41 that determines whether the distance between the next stop position and the current vehicle position is equal to or less than a predetermined distance (for example, equal to or less than 30 m) from the information from the position information acquisition unit 20, and a stop request determination unit 42 that determines whether a stopping action is being taken to pull over to the shoulder of the road at the stop position, from the information from the vehicle behavior acquisition unit 30. The stop request determination unit 42 makes a determination based on three pieces of information from the turn signal operation acquisition unit 31, the brake operation acquisition unit 32, and the steering operation acquisition unit 33.

[0018] The control device 40 is an ECU and has a calculation unit (CPU), a storage unit having a ROM and a RAM, an input unit (input interface), and an output unit (output interface). Information (electrical signals) from the position information acquisition unit 20 and the vehicle behavior acquisition unit 30 is read into the calculation unit via the input unit, and is determined in the calculation unit according to a control program stored in the ROM or RAM.

[0019] Fig. 2 is a flowchart showing an example of a control routine of the control device 40. The control routine shown in Fig. 2 is executed at predetermined time intervals after the vehicle's traction motor is supplied with power and starts to drive.

[0020] First, in step S0, information is input from the position information acquisition unit 20 and the vehicle behavior acquisition unit 30. Next, in step S1, based on information from the turn signal operation acquisition unit 31 of the vehicle behavior acquisition unit 30, the stop request determination unit 42 determines whether or not a turn signal is being operated to point to the shoulder of the road at the stop position. If it is determined in step S1 that a turn signal is not being operated, the process proceeds to step S6, where it proceeds directly (without sending a signal to the brake control ECU 50 to generate a braking force difference between the left and right wheels, and without sending a signal to the power steering ECU 51 to weaken the electric power steering motor force) to the end step. The brake control ECU 50 is an ECU that controls an automatic brake pressure applying device (ESC (Electronic Stability Control) actuator) for each wheel. The power steering ECU 51 is an ECU that controls the electric power steering motor. On the other hand, if it is determined in step S1 that the turn signal is being operated, the process proceeds to step S2.

[0021] In step S2, the stop request determination unit 42 determines whether or not a steering operation is being performed toward the shoulder of the road from the stop position based on information from the steering operation acquisition unit 33 of the vehicle behavior acquisition unit 30. If it is determined in step S2 that a steering operation is not being performed, the process proceeds to step S6, where it directly proceeds to the end step (without sending a signal to the brake control ECU 50 to generate a braking force difference between the left and right wheels, and without sending a signal to the power steering ECU 51 to weaken the electric power steering motor force). On the other hand, if it is determined in step S2 that a steering operation is being performed, the process proceeds to step S3.

[0022] In step S3, the stop request determination unit 42 determines whether or not a brake operation is being performed based on information from the brake operation acquisition unit 32 of the vehicle behavior acquisition unit 30. In steps S1 to S3, the control device 40 determines from the information from the vehicle behavior acquisition unit 30 whether or not a stopping action is being performed to pull over to the shoulder of the road at the stopping position.

[0023] If it is determined in step S3 that the brakes are not being applied, the process proceeds to step S6, and then proceeds to the end step (without sending a signal to the brake control ECU 50 to generate a braking force difference between the left and right wheels, and without sending a signal to the power steering ECU 51 to weaken the electric power steering motor force).On the other hand, if it is determined in step S3 that the brakes are being applied, the process proceeds to step S4.

[0024] In step S4, the stop position approach determination unit 41 determines whether the distance between the next stop position and the current estimated vehicle position is equal to or less than a predetermined distance (for example, equal to or less than 30 m) based on information from the position information acquisition unit 20. If it is determined in step S4 that the distance between the next stop position and the current estimated vehicle position is not equal to or less than the predetermined distance, the process proceeds to step S6, and then proceeds to the end step (without sending a signal to the brake control ECU 50 to generate a braking force difference between the left and right wheels, and without sending a signal to the power steering ECU 51 to weaken the electric power steering motor force). On the other hand, if it is determined in step S4 that the distance between the next stop position and the current estimated vehicle position is equal to or less than the predetermined distance, the process proceeds to step S5.

[0025] In step S5, it is determined from the information from vehicle behavior acquisition unit 30 in steps S1 to S3 that a stopping action is being taken to pull over to the shoulder of the road at the stopping position and stop the vehicle, and in step S4 it is determined from the information from position information acquisition unit 20 that the distance between the stopping position and the vehicle position is less than a predetermined distance, so (i) a signal to brake control ECU 50 is sent to increase the braking force of the wheels on the shoulder side of the stopping position more than the braking force of the wheels on the opposite side, and (ii) a signal to decrease the electric power steering motor force is sent to power steering ECU 51. The order of (i) and (ii) above does not matter, and they may be performed simultaneously. Then, the process proceeds to the end step.

[0026] In the above (i), the difference between the braking force of the wheels on the shoulder side of the stopping position and the braking force of the wheels on the opposite side is determined according to (proportional to) the steering angle. Also, in the above (i), the wheels on the shoulder side to which the braking force is increased may be only the front wheels, only the rear wheels, or both the front and rear wheels. In the above (ii), weakening the electric power steering motor force means weakening the motor force compared to when this control is not implemented, and also includes not operating the electric power steering motor.

[0027] If the brake operation is completely released while the control device 40 is executing the control of step S5, it may be determined in step S3 that the brake operation is not being performed, and the control of step S5 may be turned OFF, causing the vehicle's direction of travel to suddenly change, even though the steering angle has not changed. Therefore, the control device 40 executes the control routine shown in Fig. 3 while executing the control of step S5.

[0028] Fig. 3 is a flowchart showing a control routine of the control device 40 during the control of step S5 in Fig. 2. The control routine shown in Fig. 3 is performed at predetermined time intervals while the control of step S5 in Fig. 2 is being performed.

[0029] First, in step S10, information is input from the vehicle behavior acquisition unit 30. Next, in step S11, it is determined based on the information from the vehicle behavior acquisition unit 30 whether only the brake operation has begun to be released (whether the brake has begun to be turned off or the brake pedal has begun to be released) while the turn signal operation and steering operation are continuing. If it is determined in step S11 that the turn signal operation and steering operation are continuing and the brake operation has not begun to be released, the process proceeds to step S13, where the control of step S5 in FIG. 2 is carried out as is, and the process proceeds to the end step. On the other hand, if it is determined in step S11 that only the brake operation has begun to be released while the turn signal operation and steering operation are continuing, the process proceeds to step S12.

[0030] In step S12, a signal to maintain the control for increasing the braking force of the wheels on the shoulder side of the stopping position more than the braking force of the wheels on the opposite side in accordance with the steering angle (maintaining the control (i) in step S5) is sent to the brake control ECU 50. Then, the process proceeds to the end step.

[0031] Figure 4(a) is a diagram showing an example of the work difference between the braking forces of the left and right wheels when the control of step S5 in Figure 2 is being carried out, i.e., when the brakes are being operated, and Figure 4(b) is a diagram showing the work difference between the braking forces of the left and right wheels when only the brake operation is released from the state of Figure 4(a) without changing the turn signals or the steering angle. FIG. 4(a) shows a case where the braking force work of the wheels opposite the shoulder is 700 Nm, the braking force work of the wheels opposite the shoulder is 1000 Nm, and the braking force work difference between the left and right wheels is 300 Nm. FIG. 4(b) shows that even when the brake operation is released and the braking force work of the wheels opposite the shoulder becomes 0 Nm, the braking force work of the wheels on the shoulder is maintained at 300 Nm (the braking force of the wheels on the shoulder is not set to zero) in order to maintain the work difference between the left and right wheels of 300 Nm. In this way, even when only the brake operation is released during the control of step S5 of FIG. 2 (i.e., when the control of step S5 of FIG. 2 is released), maintaining the braking force work difference between the left and right wheels prevents the vehicle from suddenly changing its direction of travel even when the steering angle is not changed.

[0032] Next, the operation and effects of the embodiment of the present invention will be explained. (A) In the case of a bus, the vehicle typically steers in the same direction (left in Japan) at each stop (bus stop), often steering in the same direction (about once per kilometer). Therefore, it is desirable to reduce steering power consumption to improve fuel economy. In this embodiment of the present invention, when both of the following conditions are satisfied (steps S1 to S4 in FIG. 2 ): the control device 40 determines, based on information from the position information acquisition unit 20, that the distance between the stop position and the vehicle position is less than a predetermined distance; and the control device 40 determines, based on information from the vehicle behavior acquisition unit 30, that a vehicle is attempting to pull over to the shoulder of the road at the stop position and stop the vehicle (steps S1 to S4 in FIG. 2 ), it controls the braking force of the wheels on the shoulder side of the stop position more than the braking force of the wheels on the opposite side. This allows the vehicle to turn toward the shoulder due to the braking force difference without steering. Therefore, control can be performed to reduce the electric power steering motor force (step S5), thereby reducing power consumption compared to when control to reduce the power steering motor force is not performed. In other words, it is possible to reduce the power used for steering when a bus or other vehicle frequently stops on the shoulder.

[0033] (B) The steering angle required to pull over to the shoulder of a road at a predetermined stopping location such as a bus stop is relatively small, unlike when turning at a right angle on a road, so the present invention, which turns the vehicle by using the difference in braking force between the left and right wheels, can be realized relatively easily.

[0034] (C) When the control device 40 determines, based on information from the vehicle behavior acquisition unit 30, that the turn signal has been operated toward the shoulder of the stopping position, that the brakes have been operated, and that the steering operation direction is toward the shoulder of the stopping position (steps S1 to S3), it determines that a stopping action is being taken to pull over to the shoulder of the stopping position and stop the vehicle.Therefore, it can determine that a stopping action is being taken based on three pieces of information, thereby improving the accuracy of the determination.

[0035] (D) During the control of step S5 in FIG. 2, if it is determined based on information from the vehicle behavior acquisition unit 30 that only the brake operation of the three pieces of information has begun to be released, the control device 40 maintains control to make the braking force of the wheels on the shoulder side of the stopping position stronger than the braking force of the wheels on the opposite side (step S12 in FIG. 3). Therefore, even if the brake operation is released during the control of step S5 and the control of step S5 is released, it is possible to prevent the vehicle's traveling direction from suddenly changing even though the steering angle has not changed.

[0036] In the embodiment of the present invention, the location information acquisition unit 20 is provided, the control device 40 has the stop position approach determination unit 41, and the determination step S4 in Fig. 2 is performed. However, these (the location information acquisition unit 20, the stop position approach determination unit 41, and the determination step S4) may be omitted. In this case, the claims of the present invention are as follows. [1] a vehicle behavior acquisition unit that acquires information on a vehicle behavior for pulling over to a shoulder of a road at a predetermined stopping position; a control device that controls braking forces of left and right wheels based on information from the vehicle behavior acquisition unit; and When the control device determines from the information of the vehicle behavior acquisition unit that a stopping action is being taken to pull over to the shoulder of the road at the stopping position and stop the vehicle, it performs control to strengthen the braking force of the wheels on the shoulder side of the stopping position more than the braking force of the wheels on the opposite side. [2] The vehicle braking control system described in [1], wherein when the control device determines from the information of the vehicle behavior acquisition unit that a stopping action is being taken to pull over to the shoulder of the road at the stopping position, the control device performs control to weaken the power steering motor force compared to when the stopping action is not being taken. [3] The vehicle behavior acquisition unit acquires three pieces of information: information on blinker operation, information on brake operation, and information on steering operation; The vehicle braking control system described in [1], wherein the control device determines that a stopping action is being taken to pull over to the shoulder of the stopping position when, based on information from the vehicle behavior acquisition unit, it determines that a turn signal is being operated toward the shoulder of the stopping position, that a brake operation is being performed, and that the steering operation direction is toward the shoulder of the stopping position. [4] The vehicle braking control system described in [3], wherein the control device maintains the control of making the braking force of the wheels on the shoulder side of the stopping position stronger than the braking force of the wheels on the opposite side when, while implementing control to make the braking force of the wheels on the shoulder side of the stopping position stronger than the braking force of the wheels on the opposite side, it determines based on information from the vehicle behavior acquisition unit that only the brake operation of the three pieces of information has begun to be released. [Explanation of symbols]

[0037] 10 Vehicle braking control system 20 Location information acquisition section 30 Vehicle Behavior Acquisition Department 31 Turn signal operation acquisition unit 32 Brake operation acquisition unit 33 Steering operation acquisition unit 40 Control device 41 Parking position approach determination unit 42 Stop request determination section 50 Brake control ECU 51 Power steering ECU

Claims

1. a location information acquisition unit that acquires location information of a vehicle; a vehicle behavior acquisition unit that acquires information on vehicle behavior for pulling over to the shoulder of a road at a predetermined stopping position; a control device that controls braking forces of left and right wheels based on information from the position information acquisition unit and the vehicle behavior acquisition unit; and The control device When both of the following conditions are satisfied: it is determined from the information of the position information acquisition unit that the distance between the stopping position and the vehicle position is equal to or shorter than a predetermined distance; and it is determined from the information of the vehicle behavior acquisition unit that a stopping behavior is being performed to pull over to the shoulder of the road at the stopping position and stop the vehicle, control is performed to strengthen the braking force of the wheels on the shoulder side of the stopping position more than the braking force of the wheels on the opposite side, Furthermore, the vehicle braking control system performs control to weaken the power steering motor force compared to when both of these conditions are not satisfied.

2. A location information acquisition unit that acquires vehicle location information; a vehicle behavior acquisition unit that acquires information on vehicle behavior for pulling over to the shoulder of a road at a predetermined stopping position; a control device that controls braking forces of left and right wheels based on information from the position information acquisition unit and the vehicle behavior acquisition unit; and the vehicle behavior acquisition unit acquires three pieces of information: information on blinker operation, information on brake operation, and information on steering operation; The control device When both of the following conditions are satisfied: it is determined from the information of the position information acquisition unit that the distance between the stopping position and the vehicle position is equal to or shorter than a predetermined distance; and it is determined from the information of the vehicle behavior acquisition unit that a stopping behavior is being performed to pull over to the shoulder of the road at the stopping position and stop the vehicle, control is performed to strengthen the braking force of the wheels on the shoulder side of the stopping position more than the braking force of the wheels on the opposite side, A vehicle braking control system that determines that a stopping action is being taken to pull over to the shoulder of the stopping position when, based on information from the vehicle behavior acquisition unit, it determines that a turn signal is being operated toward the shoulder of the road in the stopping position, that a brake is being operated, and that the steering operation direction is toward the shoulder of the road in the stopping position.

3. A braking control system for a vehicle as described in claim 2, wherein, while implementing control to make the braking force of the wheels on the shoulder side of the stopping position stronger than the braking force of the wheels on the opposite side, if the control device determines based on information from the vehicle behavior acquisition unit that only the brake operation of the three pieces of information has begun to be released, it maintains the control to make the braking force of the wheels on the shoulder side of the stopping position stronger than the braking force of the wheels on the opposite side.

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