Driver assistance systems

Abstract

In vehicles that limit the driving force to maintain a certain distance from the vehicle ahead, the aim is to suppress the feeling of the vehicle lurching forward during lane changes and enable appropriate acceleration. [Solution] The driver assistance system assists the driver in driving their own vehicle and includes a control device. The control device performs torque limiting processing to limit the output torque of the vehicle's drive system to a limiting torque in response to the driver's requested torque based on the accelerator pedal opening of the vehicle's accelerator pedal, in order to maintain a certain distance between the vehicle and the preceding vehicle. When the start of a lane change operation by the driver of the vehicle is detected, the torque limiting processing includes a torque limiting correction process that increases the limiting torque based on the amount the accelerator pedal has been pressed since the detection of the start of the lane change operation.

Description

Technical Field

[0001] The present disclosure relates to a driving support system for a vehicle.

Background Art

[0002] Patent Document 1 discloses a driving support system for a vehicle. When the inter-vehicle distance of the host vehicle with respect to the preceding vehicle is smaller than a safe inter-vehicle distance, the driving support system prohibits an intervention of a driving operation for accelerating the host vehicle (override by an acceleration operation of the driver).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Even if the inter-vehicle distance of the host vehicle with respect to the preceding vehicle in the current own lane is relatively small, an acceleration operation of the driver performed along with a lane change of the host vehicle may be permitted. However, if the driving force limitation of the host vehicle that was being performed before the start of the lane change is simply released, a sense of jerk due to sudden acceleration may occur in the host vehicle.

[0005] The present disclosure has been made in view of the above problems, and in a vehicle that performs driving force limitation to keep the inter-vehicle distance of the host vehicle with respect to the preceding vehicle at a certain level or more, it is an object to provide a driving support system that can suppress a sense of jerk of the host vehicle during a lane change and realize appropriate acceleration.

Means for Solving the Problems

[0006] The driver assistance system described herein assists the driver in driving their own vehicle and includes a control device. The control device performs torque limiting processing to limit the output torque of the vehicle's drive system to a limiting torque in response to the driver's requested torque based on the accelerator pedal opening of the vehicle's accelerator pedal, in order to maintain a certain distance between the vehicle and the preceding vehicle. The torque limiting processing includes a limiting torque correction process that increases the limiting torque based on the amount the accelerator pedal has been pressed since the detection of the start of a lane change operation by the driver. [Effects of the Invention]

[0007] When torque limiting is applied, the vehicle's drive system does not generate output torque exceeding the limit torque, regardless of the accelerator pedal position, before the driver initiates a lane change operation. According to this disclosure, output torque is generated to correspond to the amount the accelerator pedal is pressed further after the lane change operation begins, regardless of the accelerator pedal position before the lane change operation begins. This suppresses the feeling of sudden lurching during lane changes and enables appropriate acceleration. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically shows an example of the configuration of a driver assistance system according to an embodiment. [Figure 2] This flowchart shows an example of the flow of processing related to the torque limiting function (torque limiting processing) according to the embodiment. [Figure 3] This is a supplementary diagram for explaining the torque limiting correction process included in the torque limiting process. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described with reference to the attached drawings.

[0010] 1. Configuration of the driver assistance system Figure 1 is a schematic diagram showing an example of the configuration of a driver assistance system 10 according to an embodiment. The driver assistance system 10 is installed in a vehicle (own vehicle) 1 and assists the driver 2 in driving the vehicle 1. The driver assistance system 10 includes a vehicle state sensor 12, a recognition sensor 14, a turn signal switch 16, a running gear 18, and an electronic control unit (ECU) 20.

[0011] The vehicle state sensor 12 detects the state of vehicle 1. The vehicle state sensor 12 includes, for example, a vehicle speed sensor, a longitudinal acceleration sensor, an accelerator pedal sensor, a brake pedal sensor, and a steering angle sensor. The recognition sensor 14 recognizes (detects) the surrounding conditions of vehicle 1. Examples of recognition sensors 14 include cameras, radar, etc.

[0012] The turn signal switch 16 is used to detect turn signal operation by driver 2 and outputs an operation signal to the ECU 20 in accordance with the operation of the turn signal switch 16 by driver 2. The turn signal operation signal includes a signal corresponding to a left turn, a signal corresponding to a right turn, and a signal corresponding to the turn signal off state.

[0013] The running gear 18 is a device that operates the vehicle 1. For example, the running gear 18 includes a drive system, a braking system, and a steering system. The drive system includes, for example, at least one of an electric motor and an internal combustion engine for driving (accelerating) the vehicle 1 and generates the driving force of the vehicle 1. The braking system includes a brake actuator for braking (decelerating) the vehicle 1 and generates the braking force of the vehicle 1. The steering system includes, for example, a steering motor for steering the vehicle 1.

[0014] The ECU 20 is a computer that controls the vehicle 1 and corresponds to an example of a "control device" according to this disclosure. The ECU 20 includes a processor 22 and a storage device 24. The processor 22 performs various processes. These processes include processes related to the torque limiting function F described later. The storage device 24 stores various information necessary for the processing by the processor 22. The various processes performed by the ECU 20 are realized by the processor 22 executing a computer program. The computer program is stored in the storage device 24. Alternatively, the computer program may be recorded on a computer-readable recording medium. The ECU 20 may be configured by combining multiple ECUs.

[0015] 2. Torque limiting function In this embodiment, the driver assistance system 10 (ECU 20) controls the running gear 18 to activate predetermined driver assistance functions. The predetermined driver assistance functions include a torque limiting function F to maintain a certain distance D between the vehicle 1 and a preceding vehicle (e.g., preceding vehicle 3 (see Figure 1)).

[0016] To achieve the torque limiting function F described above, the ECU 20 performs the following "torque limiting process". Specifically, in the torque limiting process, the ECU 20 limits the output torque T of the vehicle 1's drive system to a limiting torque LT in relation to the torque requested by the driver 2 based on the accelerator pedal opening AP of the vehicle 1, in order to maintain the inter-vehicle distance D above a certain level. As a result, the driving force of the vehicle 1 is controlled (limited) in order to maintain the inter-vehicle distance D above a certain level. In addition, to achieve the torque limiting function F, the ECU 20 may also control the braking system included in the running gear 18. Specifically, the ECU 20 may control the braking force of the vehicle 1 in order to maintain the inter-vehicle distance D above a certain level.

[0017] Even if the inter-vehicle distance D of the host vehicle 1 with respect to the preceding vehicle in the current own lane (e.g., preceding vehicle 3) is relatively small, the acceleration operation of the driver 2 performed along with the lane change of the host vehicle 1 may be permitted. However, if the driving force limitation of the host vehicle 1 that was being performed before the start of the lane change is simply released, a sense of jerk due to sudden acceleration may occur in the host vehicle 1.

[0018] More specifically, the torque limitation function F that limits the output torque T of the drive device (in other words, the driving force of the host vehicle 1) according to the inter-vehicle distance D basically does not allow the driver 2 to override the limitation by depressing the accelerator pedal. On the other hand, when the driving force limitation is being performed, the driver 2 may, for example, attempt to change lanes for the purpose of overtaking the preceding vehicle 3. In such a case, the driving force limitation may be temporarily released. However, when the driving force limitation is being performed, the driver 2 may continue driving while inadvertently depressing the accelerator pedal too far. Therefore, if the driving force limitation is simply released when the start of the lane change is detected, an accelerator opening degree AP that is too large will be reflected in the driving force, and a sense of jerk may occur.

[0019] Therefore, the torque limitation process according to the present embodiment includes a "limiting torque correction process". According to the limiting torque correction process, when the ECU 20 detects the start of the lane change operation of the host vehicle 1 by the driver 2 during the execution of the torque limitation process, the ECU 20 increases the limiting torque LT based on the amount of increase in the depression of the accelerator pedal from the detection time point t0 of the start.

[0020] FIG. 2 is a flowchart showing an example of the flow of a process (torque limitation process) related to the torque limitation function F according to the present embodiment. The process of this flowchart is repeatedly executed while the host vehicle 1 is running. FIG. 3 is a supplementary diagram for explaining the limiting torque correction process included in the torque limitation process.

[0021] In step S100, the ECU 20 determines whether a predetermined condition for enabling the torque limit function F for maintaining the inter-vehicle distance D is satisfied. As a result, if the torque limit function F is not valid (step S100; No), the process proceeds to the end. On the other hand, if the torque limit function F is valid (step S100; Yes), the process proceeds to step S102.

[0022] In step S102, the ECU 20 calculates the inter-vehicle distance D based on the information of the recognition sensor 14 (e.g., camera, radar). Then, the ECU 20 determines whether the calculated inter-vehicle distance D is less than or equal to a predetermined value THd. The predetermined value THd is, for example, preset in advance as a value necessary to keep the inter-vehicle distance D at a certain level or more. If the inter-vehicle distance D is longer than the predetermined value THd (step S102; No), that is, if the limitation of the output torque T by the torque limit process is not necessary, the process proceeds to the end.

[0023] On the other hand, if the inter-vehicle distance D is less than or equal to the predetermined value THd (step S102; Yes), that is, if the limitation of the output torque T by the torque limit process is necessary, the process proceeds to step S104. In step S1, the ECU 20 calculates a limit torque LT1 (first limit torque) corresponding to the currently calculated inter-vehicle distance D as the limit torque LT. More specifically, the ECU 20 calculates the limit torque LT1 such that, for example, the shorter the calculated inter-vehicle distance D, the lower it becomes. However, the limit torque LT1 may be calculated as a constant value that does not depend on, for example, the calculated inter-vehicle distance D. After that, the process proceeds to step S106.

[0024] In step S106, the ECU 20 calculates the accelerator opening degree AP1 (first accelerator opening) from the limiting torque LT1 calculated in step S104 and the vehicle speed V of the vehicle 1. The vehicle speed V is obtained, for example, using a vehicle state sensor 12 (e.g., vehicle speed sensor). More specifically, the ECU 20's storage device 24 stores the relationship between the accelerator opening degree AP and the output torque T with respect to the vehicle speed V, as shown in Figure 3, for example, as a map or relational expression. Based on this relationship, the ECU 20 calculates the accelerator opening degree AP1 (first accelerator opening) corresponding to the current vehicle speed V (e.g., V1) and limiting torque LT1 of the vehicle 1. The process then proceeds to step S108.

[0025] In step S108, the ECU 20 determines whether or not the driver 2 has operated the turn signal based on the operation signal of the turn signal switch 16. This determination is performed to detect the start of a lane change operation by the driver 2 of the vehicle 1. The detection of the start of a lane change operation may be performed by, for example, determining whether or not the driver 2 has steered the vehicle 1 using a steering angle sensor, instead of determining whether or not the turn signal has been operated.

[0026] If the turn signal is activated (step S108; Yes), that is, if the start of a lane change operation is detected, the process proceeds to step S110. In step S110, the ECU 20 stores the accelerator pedal opening degree AP at the time t0 when the turn signal operation (start of lane change operation) is detected as the reference opening degree AP0 in the storage device 24. The process then proceeds to step S114. On the other hand, if the turn signal is not activated (step S108; No), that is, if the start of a lane change operation is not detected, the ECU 20 sets (resets) the reference opening degree AP0 to 0 (step S112). The process then proceeds to the end. In addition, the reference opening degree AP0 is the degree to which the accelerator pedal is pressed when the driver 2 indicates their intention to change lanes by performing a lane change operation.

[0027] In step S114, the ECU 20 uses the accelerator pedal sensor included in the vehicle state sensor 12 to determine whether the accelerator pedal has been pressed further from the reference opening degree AP0 stored in step S100. More specifically, the ECU 20 may determine whether the accelerator pedal has been pressed further so that the accelerator opening degree AP becomes greater than the reference opening degree AP0 by a predetermined value or more.

[0028] If the above-mentioned additional pedal pressure occurs (step S114; Yes), the process proceeds to step S116. In step S116, the ECU 20 calculates the accelerator pedal position deviation ΔAP, which is obtained by subtracting the reference position AP0 from the accelerator pedal position AP at the time when it was determined that additional pedal pressure had occurred. This accelerator pedal position deviation ΔAP corresponds to the amount the accelerator pedal has been pressed further since the detection time t0.

[0029] In step S118, following step S116, the ECU20 calculates the accelerator opening AP2 (second accelerator opening) for lane changes. More specifically, the ECU20 calculates the accelerator opening AP2 by adding the accelerator opening deviation ΔAP calculated in step S116 to the accelerator opening AP1 calculated in step S106.

[0030] In step S120, following step S118, the ECU 20 calculates a limiting torque LT2 (second limiting torque) corresponding to the accelerator opening AP2 calculated in step S118 and the current vehicle speed V (e.g., V1) based on the above relationship (see Figure 3). More specifically, the ECU 20 calculates the limiting torque LT2 such that, for example, the larger the accelerator opening deviation ΔAP calculated in step S116, the greater the increase in the limiting torque LT1. However, the limiting torque LT2 may also be calculated to increase by a constant amount independent of the calculated accelerator opening deviation ΔAP relative to the limiting torque LT1.

[0031] Furthermore, in step S120, the ECU20 updates the limiting torque LT used in the torque limiting process with the limiting torque LT2 calculated as described above. Additionally, the limiting torque LT2 is higher than the limiting torque LT1 before the update. In other words, according to the limiting torque correction process of this embodiment, when changing lanes, the torque limiting using the limiting torque LT is relaxed according to the accelerator opening deviation ΔAP relative to the reference opening AP0.

[0032] On the other hand, if the accelerator pedal is not pressed further from the reference opening AP0 (step S114; No), the process proceeds to step S122. In step S122, the ECU20 determines whether the current accelerator opening AP has decreased to or below a predetermined accelerator OFF determination threshold (e.g., accelerator opening 0%).

[0033] If the accelerator opening AP has not decreased to below the accelerator OFF judgment threshold (step S122; No), the process proceeds to the end. On the other hand, if the accelerator opening AP has decreased to below the accelerator OFF judgment threshold (step S122; Yes), that is, if the accelerator opening AP is pressed back to below the accelerator OFF judgment threshold without any further pressing that satisfies the judgment in step S114 after detection time t0, the ECU 20 sets (resets) the reference opening AP0 to 0 (step S124).

[0034] 3. Effects When the torque limiting process described above is performed, the drive system of the vehicle 1 does not generate an output torque T greater than or equal to the limit torque LT, regardless of the accelerator opening AP, before the driver 2 starts the lane change operation. According to this embodiment, the output torque T is generated to correspond to the amount the accelerator pedal is pressed further after the lane change operation starts (accelerator opening deviation ΔAP), regardless of the accelerator opening AP before the lane change operation starts. This makes it possible to suppress the feeling of sudden lurching during lane changes and achieve appropriate acceleration.

[0035] Furthermore, as mentioned above, the limiting torque LT2 (second limiting torque) may be calculated such that the larger the accelerator opening deviation ΔAP, the greater the increase in the limiting torque LT1 (first limiting torque). This makes it possible to increase the output torque T (in other words, relax the limiting torque LT) by an amount that better matches the demands of driver 2 who pressed the accelerator pedal further after starting a lane change operation, compared to an example where the limiting torque LT2 is calculated to increase by a constant amount relative to the limiting torque LT1, regardless of the accelerator opening deviation ΔAP. This leads to an improvement in the drivability of vehicle 1.

[0036] Furthermore, as mentioned above, the limiting torque LT1 (first limiting torque) may be calculated such that it decreases as the calculated inter-vehicle distance D decreases. This allows for a more appropriate determination of the limiting torque LT1 required to maintain the inter-vehicle distance D above a certain level, compared to, for example, an example where the limiting torque LT1 is calculated as a constant value independent of the inter-vehicle distance D. [Explanation of Symbols]

[0037] 1 Vehicle (own vehicle), 3 Preceding vehicle, 10 Driver assistance system, 20 Electronic control unit (ECU), 22 Processor, 24 Memory

Claims

1. A driver assistance system that assists the driver in operating their own vehicle, Equipped with a control device, The control device performs a torque limiting process to maintain a certain distance between its vehicle and the preceding vehicle, by limiting the output torque of the vehicle's drive system to a limiting torque in response to the torque requested by the driver based on the accelerator pedal opening of the vehicle's accelerator pedal. The torque limiting process includes a torque limiting modification process that increases the limiting torque based on the amount the accelerator pedal is pressed further from the time the driver starts a lane change operation of the vehicle, when the driver starts a lane change operation of the vehicle. Driver assistance system.

2. A driver assistance system according to claim 1, The control device includes a storage device that stores the accelerator opening at the detection point as a reference opening, The torque limiting process includes calculating a first limiting torque corresponding to the distance between vehicles as the limiting torque when the distance between vehicles is less than or equal to a predetermined value. The aforementioned limiting torque correction process is performed by Based on the relationship between the accelerator opening and the output torque with respect to the vehicle speed, the first accelerator opening corresponding to the vehicle speed of the vehicle and the first limiting torque is calculated. The second accelerator opening is calculated by adding the accelerator opening deviation corresponding to the amount of increased pedal pressure to the first accelerator opening, Based on the above relationship, the second limiting torque corresponding to the second accelerator opening and the vehicle speed is calculated, The limiting torque is updated by the second limiting torque, including Driver assistance system.

3. A driver assistance system according to claim 2, The aforementioned limiting torque correction process includes calculating the second limiting torque such that the amount of increase relative to the first limiting torque increases as the accelerator opening deviation increases. Driver assistance system.

4. A driving assistance system according to claim 2 or 3, The torque limiting process includes calculating the first limiting torque such that it decreases as the distance between vehicles decreases, when the distance between vehicles is less than or equal to the predetermined value. Driver assistance system.

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