Driving assistance systems

Abstract

The present invention provides a driver assistance device that increases the likelihood of accurately determining whether or not the driver is holding the steering wheel, even when the vehicle is traveling on a road (e.g., a straight road) where the driver does not need to perform steering operations to keep the vehicle along the road. [Solution] The driver assistance device performs a predetermined non-grip control to respond to the non-grip of the steering wheel when it determines that the driver is not gripping the steering wheel. When a predetermined starting condition is met, the driver assistance device starts sway control, which causes the vehicle to sway by changing the direction of travel. After the start of sway control, if the non-operation time during which the driver does not perform steering operations on the steering wheel continues for a predetermined threshold time or longer, the device determines that the driver is not gripping the steering wheel and performs non-grip control.

Description

Technical Field

[0005] ,

[0001] The present invention relates to a driving support device that performs predetermined non-grip control when a driver is not gripping the steering wheel.

Background Art

[0002] Conventionally, a driving support device that performs predetermined warning control as non-grip control when a driver is not gripping the steering wheel is known. For example, a driving support device described in Patent Document 1 (hereinafter referred to as the "conventional device") determines whether a driver is gripping the steering wheel using a steering angle sensor, a torque sensor, a touch sensor, etc. The conventional device gives an alarm when the non-grip time during which the driver is not gripping the steering wheel is longer than a predetermined time.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] In a situation where a vehicle is traveling on a road (e.g., a straight road) for which a driver does not need to perform a steering operation to drive the vehicle along the road (hereinafter referred to as an "operation-unnecessary situation"), the steering angle and the operation torque are constant. Therefore, in such a situation, it may not be possible to accurately determine whether a driver is gripping the steering wheel using a steering angle sensor and a torque sensor. On the other hand, when a touch sensor is arranged on the steering wheel, the manufacturing cost increases.

[0005] The present invention has been made to address the above-described problems. That is, one object of the present invention is to provide a driving support device that increases the possibility of accurately determining whether a driver is gripping the steering wheel even in an operation-unnecessary situation.

[0006] The driver assistance device of the present invention (hereinafter referred to as "the device of the present invention") performs a predetermined non-gripping control to respond to the non-gripping of the steering wheel (SW) when it is determined that the driver is not gripping the steering wheel (step 370, step 520). The aforementioned driving support device, If the predetermined start conditions are met (step 330 "Yes", step 335 "No", step 345 "Yes"), the vehicle's direction of travel is changed to initiate sway control (steps 350, 510), If, after the start of the sway control, the driver does not perform any steering operations on the steering wheel for a period of time (Tnon) that exceeds a predetermined threshold time (step 355 "Yes", step 365 "Yes"), it is determined that the driver is not gripping the steering wheel, and the non-grip control is performed (step 370, step 520). It is structured in this way.

[0007] According to the present invention, sway control is initiated when the starting conditions are met. When sway control is initiated, the driver is highly likely to perform steering operations to suppress the vehicle's sway. As a result, even in situations where no operation is required, the present invention can accurately determine whether or not the driver is gripping the steering wheel switch. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic system configuration diagram of a driver assistance device according to an embodiment of the present invention. [Figure 2] This is an explanatory diagram illustrating an example of the operation of a driver assistance device according to an embodiment of the present invention. [Figure 3] Figure 1 shows a flowchart of a portion of the gripping determination routine executed by the CPU of the ECU. [Figure 4] Figure 1 is a flowchart of the remaining part of the grip determination routine executed by the CPU of the ECU. [Figure 5] This is a flowchart of a non-operation control routine executed by the CPU of the ECU shown in FIG. 1.

Embodiments for Carrying Out the Invention

[0009] The driving support device 10 according to an embodiment of the present invention (hereinafter referred to as "this device 10") is applied to the vehicle VA and includes the components shown in FIG. 1. In this specification, the "ECU 20" is an electronic control device mainly comprising a microcomputer. The ECU 20 is also referred to as a control unit, a controller, and a computer. The microcomputer includes a CPU (processor), a ROM, a RAM, an interface (I / F), etc. The functions realized by the ECU 20 may be realized by a plurality of ECUs.

[0010] The camera 22 acquires image data by photographing the scenery in front of the vehicle VA. The ECU 20 acquires the image data from the camera 22. The vehicle speed sensor 24 measures a vehicle speed Vs representing the speed of the vehicle VA. The steering torque sensor 26 is disposed on a steering shaft SS connected to the steering wheel SW, and measures the torque generated on the steering shaft SS as a steering torque Tr. The acceleration sensor 28 measures a lateral acceleration G in the vehicle width direction (i.e., the lateral direction) of the vehicle VA. The ECU 20 acquires the measurement values of these sensors 24 to 28.

[0011] The steering motor 30 is incorporated in the steering mechanism 32. The steering mechanism 32 is a mechanism for steering the steered wheels in response to a steering operation of the steering wheel SW by the driver. Further, the steering motor 30 applies an automatic steering torque Tra for changing the steering angle (traveling direction of the vehicle VA) of the steered wheels in response to an instruction from the ECU 20.

[0012] The display 34 is disposed in the vehicle interior of the vehicle VA and displays warning display elements described later. The speaker 36 is disposed in the vehicle interior of the vehicle VA and outputs a warning sound.

[0013] <LTA Control> This device 10 is capable of performing LTA (Lane Tracing Assist) control. LTA control is a control that applies automatic steering torque Tra so that the vehicle VA travels along the lane without the driver having to operate the steering wheel SW. LTA control is one of the controls for autonomous driving. Details of LTA control are described, for example, in Japanese Patent Publication No. 2024-130577. LTA control is sometimes referred to as "lane keeping control". The driver is required to hold the steering wheel SW even when LTA control is being performed.

[0014] (Summary of operation) Referring to Figure 2, the operation of the ECU 20 of this device 10 will be explained. When LTA control is being performed, the ECU 20 of this device 10 determines whether the magnitude of the operating torque Trs (|Trs|) is less than the threshold torque Trth (see time t1 shown in Figure 2). The operating torque Trs is the torque applied to the steering shaft SS by the driver operating the steering wheel SW. The operating torque Trs is obtained by subtracting the automatic steering torque Tra from the steering torque Tr measured by the steering torque sensor 26. Hereinafter, the state in which the magnitude of the operating torque Trs (|Trs|) is less than the threshold torque Trth will be referred to as the "low torque state". The duration of the low torque state may also be referred to as the "non-operation time Tnon".

[0015] If both of the following conditions 1 and 2 are met, the ECU 20 determines that the start conditions have been met and starts the wobble control (see time t2 shown in Figure 2). Condition 1: The non-operation time Tnon is equal to or greater than the predetermined execution time Texe. Second condition: There is no curved road within a predetermined distance in front of vehicle VA, or the arrival time Tar required for vehicle VA to reach a curved road is equal to or greater than the threshold arrival time Tarth. In the wobbling control, the ECU 20 causes the vehicle VA to wobble in the vehicle width direction (to snake) by changing the traveling direction of the vehicle VA (by steering the steered wheels). More specifically, the ECU 20 controls the steering motor 30 so as to apply a wobbling torque Trf for causing the vehicle VA to wobble as an automatic steering torque Tra. When the wobbling control starts, as shown in FIG. 2, every time a predetermined time elapses, the traveling direction of the vehicle VA switches from the right direction to the left direction (from the left direction to the right direction), and the vehicle VA travels while wobbling. As shown in FIG. 2, the maximum value of the magnitude of the wobbling torque Trf is set to a value larger than the threshold torque Trth.

[0016] When the wobbling control is started, usually, the driver performs a steering operation to suppress the wobbling of the vehicle VA. The operation torque Trs due to such a steering operation is, as shown by the dashed-dotted line in FIG.  2, delayed with respect to the wobbling torque Trf, has substantially the same magnitude as the wobbling torque Trf, and is a torque in the opposite direction to the wobbling torque Trf. When the driver performs such a steering operation, the magnitude of the operation torque Trs becomes equal to or greater than the threshold torque Trth.

[0017] When the small torque state continues for a predetermined threshold warning time at time t3 after the start of the wobbling control (in other words, at time t3 when the non-operation time Tnon from time t1 continues for the warning time Tal), the ECU 20 determines that the driver is not holding the steering wheel SW and performs warning control. In the warning control, the ECU 20 displays a warning display element indicating that the driver is not holding the steering wheel SW on the display 34 and outputs a warning sound from the speaker 36.

[0018] At time t4 when the small torque state continues for a further predetermined time (in other words, at time t4 when the non-operation time Tnon from time t1 continues for the end time Tend), the ECU 20 performs end control to end the LTA control.

[0019] As described above, in this embodiment, when a predetermined start condition is satisfied, the ECU 20 starts the wobbling control, and when the non-operation time Tnon continues for a threshold warning time or more from the start of the wobbling control, it is determined that the driver is not gripping the steering wheel SW. During the execution of the wobbling control, the driver is highly likely to perform a steering operation to suppress the wobbling of the vehicle VA. Thus, even in a situation where operation is not required (for example, when the vehicle VA is traveling on a straight road), the device 10 can accurately determine whether the driver is gripping the steering wheel SW. As a result, the device 10 can reduce the possibility that warning control is performed and the possibility that the LTA control ends even though the driver is gripping the steering wheel SW. Further, the device 10 only needs to include the steering torque sensor 26 and does not need to include a touch sensor. Thereby, the manufacturing cost can be reduced.

[0020] (Specific operation) The CPU of the ECU 20 executes the routine shown by the flowchart in FIGS. 3 and 5 every time a predetermined time elapses.

[0021] <Gripping determination routine> When an appropriate time comes, the CPU starts processing from step 300 in FIG. 3, and the processing proceeds to step 305. In step 305, the CPU determines whether the LTA control is being executed.

[0022] When the CPU is executing the LTA control, the CPU determines "Yes" in step 305 and executes steps 310 to 320.

[0023] Step 310: The CPU obtains the steering torque Tr based on the measured value of the steering torque sensor 26. Step 315: The CPU obtains the operation torque Trs by subtracting the automatic steering torque Tra from the steering torque Tr. Step 320: The CPU determines whether the magnitude (|Trs|) of the operation torque Trs is less than the threshold torque Trth.

[0024] If the magnitude of the operating torque Trs (|Trs|) is less than the threshold torque Trth, the CPU determines "Yes" in step 320 and executes steps 325 and 330. Step 325: The CPU adds "1" to the idle time Tnon. Step 330: The CPU determines whether the non-operation time Tnon is greater than or equal to the execution time Texe.

[0025] If the non-operation time Tnon is less than the execution time Texe, the CPU determines "No" in step 330, and the process proceeds to step 395. In step 395, the CPU terminates this routine.

[0026] If the non-operation time Tnon is greater than or equal to the execution time Texe, the CPU determines "Yes" in step 330, and the process proceeds to step 335. In step 335, the CPU determines, based on the image data, whether or not a curved road exists within a predetermined distance in front of the vehicle VA. More specifically, the CPU identifies the white line that demarcates the lane in which the vehicle VA is traveling, based on the image data, and determines whether or not a curved road exists based on the curvature of that white line.

[0027] If a curved road exists, the CPU determines "Yes" in step 335 and executes steps 340 and 345. Step 340: The CPU obtains the arrival time Tar by dividing the distance between the vehicle VA and the entrance to the curved road by the vehicle speed Vs. Step 345: The CPU determines whether the arrival time Tar is greater than or equal to the threshold arrival time Tarth.

[0028] If the arrival time Tar is greater than or equal to the threshold arrival time Tarth, the CPU determines that the start condition has been met. In this case, the CPU determines "Yes" in step 345, and the process proceeds to step 350. In step 350, the CPU sets the execution flag Xexe to "1". The execution flag Xexe is set to "1" when sway control is performed and to "0" when sway control is not performed. The execution flag Xexe is set to "0" in the initialization routine. The CPU executes the initialization routine when the ignition key switch (not shown) of the vehicle VA is changed from the off position to the on position.

[0029] The process then proceeds to step 355 shown in Figure 4. In step 355, the CPU determines whether the non-operation time Tnon is greater than or equal to the alarm time Tal.

[0030] If the non-operation time Tnon is less than the alarm time Tal, the CPU determines "No" in step 355, and the process proceeds to step 395.

[0031] If the non-operation time Tnon is greater than or equal to the alarm time Tal, the CPU determines "Yes" in step 355 and executes steps 360 and 365. Step 360: The CPU sets the alarm flag Xal to "1". The alarm flag Xal is set to "1" when alarm control is performed and to "0" when alarm control is not performed. The alarm flag Xal is set to "0" in the initialization routine. Step 365: The CPU determines whether the non-operation time Tnon is greater than or equal to the end time Tend.

[0032] If the non-operation time Tnon is greater than or equal to the end time Tend, the CPU determines "Yes" in step 365 and executes steps 370 and 375. Step 370: The CPU terminates LTA control. Step 375: The CPU sets the idle time Tnon to "0", and sets the execution flag Xexe and alarm flag Xal to "0". The process then proceeds to step 395.

[0033] If the CPU is not performing LTA control when the process proceeds to step 305 shown in Figure 3, the CPU determines "No" in step 305, and the process proceeds to step 375 shown in Figure 4.

[0034] If the magnitude of the operating torque Trs (|Trs|) is greater than or equal to the threshold torque Trth when the process proceeds to step 320 shown in Figure 3, the CPU determines "No" in step 320, and the process proceeds to step 375 shown in Figure 4.

[0035] If no curved path exists when the process proceeds to step 335 shown in Figure 3, the CPU determines "No" in step 335 and the process proceeds to step 350.

[0036] If the time to reach Tar is less than the threshold time to reach Tarth when the process proceeds to step 345, the CPU determines "No" in step 345, and the process proceeds to step 355 as shown in Figure 4.

[0037] If the non-operation time Tnon is less than the alarm time Tal when the process proceeds to step 355, the CPU determines "No" in step 355 and the process proceeds to step 395.

[0038] If the non-operation time Tnon is less than the end time Tend when the process proceeds to step 365, the CPU determines "No" in step 365 and the process proceeds to step 395.

[0039] <Non-operation control routine> When the appropriate time arrives, the CPU starts processing from step 500 in Figure 5, and the processing proceeds to step 505. In step 505, the CPU determines whether the execution flag Xexe is "1".

[0040] If the execution flag Xexe is "0", the CPU determines "No" in step 505, and the process proceeds to step 595. In step 595, the CPU terminates this routine.

[0041] If the execution flag Xexe is "1", the CPU determines "Yes" in step 505 and executes steps 510 and 515. Step 510: The CPU controls the steering motor 30 to apply the wobble torque (Trf) to the steering shaft SS as an automatic steering torque (Tra). Step 515: The CPU determines whether the alarm flag Xal is "1".

[0042] If the alarm flag Xal is "0", the CPU determines "No" in step 515, and the process proceeds to step 595. If the alarm flag Xal is "1", the CPU determines "Yes" in step 515, and the process proceeds to step 520. In step 520, the CPU displays the above-mentioned alarm display elements on the display 34 and outputs the above-mentioned alarm sound from the speaker 36. After that, the process proceeds to step 595.

[0043] As described above, the device 10 determines that the driver is not gripping the steering wheel switch if the non-operation time Tnon continues for longer than the threshold alarm time after the start of sway control. This allows the device 10 to accurately determine whether or not the driver is gripping the steering wheel switch, even in situations where no operation is required.

[0044] (modified version) In the above embodiment, the non-operation time Tnon was counted when the magnitude of the operating torque Trs (|Trs|) was less than the threshold torque Trth, but it is not limited to this. The non-operation time Tnon may also be counted when the magnitude of the operating lateral acceleration Gs (|Gs|), which represents the lateral acceleration G of the vehicle VA due to steering operation, is less than the threshold lateral acceleration Gth.

[0045] The lateral acceleration Gs is obtained by subtracting the automatic lateral acceleration Ga from the lateral acceleration G measured by the acceleration sensor 28. The automatic lateral acceleration Ga is the lateral acceleration G of the vehicle VA due to LTA control or sway control. The automatic lateral acceleration Ga is obtained based on the vehicle speed Vs and the automatic steering torque Tra.

[0046] In the above embodiment, if it is determined that the driver is not gripping the steering wheel switch, both alarm control and termination control are executed; however, it is sufficient for at least one of the alarm control and termination control to be executed. The alarm control and termination control are controls to respond to the non-gripping of the steering wheel switch, and may also be referred to as non-gripping control.

[0047] In the above embodiment, the gripping determination routine shown in Figures 3 and 4 was executed only during LTA control, but it may also be executed when LTA control is not performed.

[0048] In step 335 shown in Figure 3, the CPU determined whether or not a curved road exists based on image data, but it may also determine whether or not a curved road exists by referring to map data.

[0049] This device 10 is applicable to vehicles such as engine-powered vehicles, hybrid vehicles, plug-in hybrid vehicles, fuel cell vehicles, and electric vehicles. [Explanation of Symbols]

[0050] 10...Driving assistance system, 26...Steering torque sensor, 28...Accelerometer, 30...Steering motor, 34...Display, 36...Speaker, SW...Steering wheel.

Claims

1. In a driver assistance device that performs predetermined non-gripping control to respond to the non-gripping of the steering wheel when it is determined that the driver is not gripping the steering wheel, The aforementioned driving support device, When predetermined starting conditions are met, sway control is initiated to cause the vehicle to sway by changing the direction of travel. If, after the start of the sway control, the driver does not perform any steering operations on the steering wheel for a period of time exceeding a predetermined threshold, it is determined that the driver is not gripping the steering wheel, and the non-grip control is performed. A driver assistance system configured in such a way.

2. In the driving support device according to claim 1, The driver assistance device is configured to perform non-gripping control if, after the start of the sway control, the magnitude of the operating torque generated by the steering operation is less than a predetermined threshold torque, or if, after the start of the sway control, the magnitude of the lateral acceleration of the vehicle generated by the steering operation is less than a predetermined threshold lateral acceleration, these conditions persist for a threshold time or longer. Driving assistance system.

3. In the driving support device according to claim 2, The aforementioned driving support device, A first condition is that the state in which the magnitude of the operating torque is less than the threshold torque, or the state in which the magnitude of the lateral acceleration is less than the threshold lateral acceleration, continues for a predetermined execution time or longer, The second condition is that there is no curved road within a predetermined distance in front of the vehicle, or the time it takes for the vehicle to reach the curved road is equal to or greater than a predetermined threshold time. If both conditions are met, the start condition is deemed to have been met, and the sway control is started. A driver assistance system configured in such a way.

4. In a driving assistance device according to any one of claims 1 to 3, The driver assistance device is configured to perform at least one of the following as the non-grip control: a warning control to inform the driver that the steering wheel is not being gripped, and an termination control to terminate the lane keeping control that allows the vehicle to travel along the lane without the driver performing any steering operations. Driving assistance system.

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