Driving assistance method and driving assistance device

Abstract

This driving assistance method involves determining whether there has been a change from a state of depressing an accelerator pedal to a state of re-depression of the accelerator pedal following momentary release (S6). The driving assistance method further involves executing a process of outputting an alert to a driver if it is determined that there has been a change to the state of re-depression of the accelerator pedal following momentary release (S7). Alternatively, the driving assistance method involves executing a process of suppressing vehicle acceleration based on the operation of depressing the accelerator pedal if it is determined that there has been a change to the state of re-depression of the accelerator pedal following momentary release (S17).

Description

Driving assistance method and driving assistance device

[0001] The present invention relates to a driving assistance method and a driving assistance device.

[0002] The driving control device described in Patent Document 1 listed below activates a warning device that uses reaction force when the accelerator pedal depression angle becomes large, and if the depression angle becomes even larger, activates a warning device that uses sound, light, vibration, etc., and if the depression angle becomes even larger, stops the engine.

[0003] Utility Model Registration No. 3160731

[0004] However, in the case of a device that detects and warns of strong accelerator pedal depression, the vehicle has already accelerated suddenly when the accelerator pedal is depressed strongly, so the driver may panic at the unintended acceleration and be unable to take his / her foot off the accelerator pedal.The object of the present invention is to detect accelerator operation that may be erroneous at an early stage and notify the driver.

[0005] According to one aspect of the present invention, there is provided a driving assistance method that performs at least one of a process of outputting a warning to a driver and a process of suppressing vehicle acceleration based on accelerator pedal depression. The driving assistance method determines whether the accelerator pedal has changed from a depressed state to a depressed state after a momentary accelerator release, and performs at least one of the processes if it is determined that the accelerator pedal has changed from a momentary accelerator release to a depressed state again.

[0006] According to the present invention, it is possible to detect accelerator operation that may be erroneous early and notify the driver. The objects and advantages of the present invention are realized and attained by using the elements and combinations set forth in the claims. It should be understood that both the foregoing general description and the following detailed description are merely exemplary and explanatory and are not intended to limit the invention as claimed.

[0007] FIG. 1 is a schematic configuration diagram of an example of a vehicle equipped with an accelerator pedal operation warning device of an embodiment; FIG. 2 is a block diagram of an example of the functional configuration of a controller of a first embodiment; (a) and (b) are explanatory diagrams of the operation of the accelerator pedal operation warning device of the first embodiment; FIG. 3 is a flowchart of an example of an accelerator pedal operation warning method of the first embodiment; FIG. 4 is a block diagram of an example of the functional configuration of a controller of a second embodiment; (b) is an explanatory diagram of the operation of the accelerator pedal operation warning device of the second embodiment; and (c) is a flowchart of an example of an accelerator pedal operation warning method of the second embodiment.

[0008] 1 is a schematic diagram of an example of a vehicle equipped with an accelerator pedal operation warning device according to an embodiment. Vehicle 1 includes accelerator pedal 10, accelerator sensor 11, brake pedal 12, brake sensor 13, braking / driving force controller 14, power controller 15, driving force source 16, brake controller 17, braking device 18, vehicle speed sensor 20, human-machine interface (HMI) 21, pedal actuator 22, and controller 23. Accelerator sensor 11, brake sensor 13, vehicle speed sensor 20, HMI 21, pedal actuator 22, and controller 23 constitute the accelerator pedal operation warning device according to an embodiment.

[0009] Accelerator pedal 10 is a pedal that is depressed by the driver in response to a driving force request (the driver's own intention to accelerate) or a braking force request (the driver's own intention to decelerate). Accelerator sensor 11 detects the accelerator stroke amount, which is the stroke amount (depression amount) of accelerator pedal 10, and outputs an accelerator stroke amount information signal to braking / driving force controller 14 and controller 23. Brake pedal 12 is a pedal that the driver depresses in response to a braking force request only, and is provided separately from accelerator pedal 10. Brake sensor 13 detects the brake stroke amount, which is the stroke amount (depression amount) of brake pedal 12, and outputs a brake stroke amount information signal to braking / driving force controller 14 and controller 23.

[0010] The braking / driving force controller 14 is an electronic control unit (ECU) that controls the braking force and driving force generated in the vehicle 1 based on the accelerator stroke amount, and also controls the braking force generated in the vehicle 1 based on the brake stroke amount. The braking / driving force controller 14 includes a processor and peripheral components such as a storage device. The functions of the braking / driving force controller 14 described below are realized by the processor executing a computer program stored in the storage device. The braking / driving force controller 14 may also be formed by dedicated hardware. For example, the braking / driving force controller 14 may include a functional logic circuit (e.g., an FPGA or an ASIC) configured in a general-purpose semiconductor integrated circuit.

[0011] Braking / driving force controller 14 calculates a driving torque command value, which is a command value for driving torque determined based on the accelerator stroke amount, and outputs it to power controller 15. If driving force source 16 includes an electric motor, braking / driving force controller 14 may calculate a regenerative braking torque command value, which is a command value for regenerative braking torque determined based on the accelerator stroke amount, and output it to power controller 15. Braking / driving force controller 14 also calculates a friction braking torque command value, which is a command value for friction braking torque determined based on the brake stroke amount, and outputs it to brake controller 17.

[0012] The power controller 15 is an electronic control unit that controls the drive torque generated by the drive power source 16, which may be an electric motor or an engine, and includes a processor and peripheral components such as a storage device. The power controller 15 may be formed by dedicated hardware. The power controller 15 controls the drive torque generated by the drive power source 16 based on a drive torque command value output from the braking / driving force controller 14. If the drive power source 16 includes an electric motor, the power controller 15 controls the regenerative braking torque generated by the drive power source 16 based on a regenerative braking torque command value.

[0013] Brake controller 17 is an electronic control unit that controls the friction braking torque generated in braking device 18, and includes a processor and peripheral components such as a storage device. Brake controller 17 may be formed by dedicated hardware. Brake controller 17 controls the friction torque generated in driving force source 16 based on the friction braking torque command value output from braking / driving force controller 14. Note that braking / driving force controller 14, power controller 15, brake controller 17, and controller 23 may each be separate controllers, or any or all of these controllers may be integrated into the same controller.

[0014] The vehicle speed sensor 20 detects the vehicle speed V of the vehicle 1 from the rotational speed (wheel speed) of the wheels of the vehicle 1 and the rotational speed of the drive motor and engine, which are the drive power source 16. The vehicle speed sensor 20 outputs an information signal of the vehicle speed V to the controller 23. The HMI 21 is an interface device that exchanges information between the vehicle 1 and an occupant. The HMI 21 includes display devices visible to the occupant of the vehicle 1 (e.g., a display panel provided near the meter or on the center console, the meter itself, a head-up display, etc.), lamps such as warning lights, speakers, buzzers, and controls (e.g., buttons, switches, levers, dials, touch panels, etc.). The pedal actuator 22 is an actuator that applies a physical force to the accelerator pedal 10. For example, the pedal actuator 22 may vibrate the accelerator pedal 10 based on a control signal from the controller 23, or may generate a pedal reaction force that pushes back the accelerator pedal 10 depressed by the driver.

[0015] The controller 23 is an electronic control unit that performs control to prevent the accelerator pedal 10 from being mistakenly depressed instead of the brake pedal 12. For example, the controller 23 includes a computer including a processor 23a and peripheral components such as a storage device 23b. The processor 23a may be, for example, a central processing unit (CPU) or a micro-processing unit (MPU). The storage device 23b may include any of a semiconductor storage device, a magnetic storage device, and an optical storage device. The storage device 23b may include memories such as a read-only memory (ROM) and a random access memory (RAM) used as main storage devices, as well as registers and cache memories. The functions of the controller 23 described below are realized, for example, by the processor 23a executing computer programs stored in the storage device 23b.

[0016] The controller 23 may be formed of dedicated hardware for executing each of the information processes described below. For example, the controller 23 may include a functional logic circuit configured in a general-purpose semiconductor integrated circuit. For example, the controller 23 may have a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

[0017] The controller 23 determines whether the state has changed from a state in which the accelerator pedal 10 is depressed to a state in which the accelerator pedal 10 is depressed again after a momentary accelerator release. If the state has changed from a state in which the accelerator pedal 10 is depressed again after a momentary accelerator release, the controller 23 determines that it is unclear whether the driver intends to accelerate. In this case, the controller 23 outputs a warning to the driver. This allows the controller 23 to detect an accelerator operation in which it is unclear whether the driver intends to accelerate early and outputs a warning to the driver before the vehicle 1 suddenly accelerates, so that the driver can recover from mistaking the accelerator pedal 10 for the brake pedal 12 before strongly depressing the accelerator pedal 10.

[0018] FIG. 2 is a block diagram of an example of the functional configuration of the controller 23 according to the first embodiment. The controller 23 includes an acceleration intention determination unit 30, a timer 31, and an alarm generation unit 32. The acceleration intention determination unit 30 determines whether the driver is depressing the accelerator pedal 10 (i.e., whether the accelerator pedal 10 is being depressed) based on the accelerator stroke amount detected by the accelerator sensor 11. For example, the acceleration intention determination unit 30 may determine that the driver is depressing the accelerator pedal 10 if the accelerator stroke amount is equal to or greater than a predetermined value, and may determine that the driver is not depressing the accelerator pedal 10 if the accelerator stroke amount is less than the predetermined value. The acceleration intention determination unit 30 also calculates the operation speed at which the driver depresses the accelerator pedal 10 based on the accelerator stroke amount detected by the accelerator sensor 11. For example, the acceleration intention determination unit 30 may calculate the accelerator stroke amount per unit time as the operation speed.

[0019] The acceleration intention determination unit 30 also determines whether the driver is depressing the brake pedal 12 (i.e., whether the brake pedal 12 is being depressed) based on the brake stroke amount detected by the brake sensor 13. For example, it may determine that the driver is depressing the brake pedal 12 when the brake stroke amount is equal to or greater than a predetermined value, and may determine that the driver is not depressing the brake pedal 12 when the brake stroke amount is less than the predetermined value. The acceleration intention determination unit 30 also determines whether the vehicle speed V detected by the vehicle speed sensor 20 is equal to or less than a predetermined speed Vth.

[0020] The timer 31 measures the accelerator-off time Tc, which is the period during which the driver releases the accelerator pedal 10. For example, the start time t1 of the accelerator-off time Tc may be the time when the accelerator stroke amount decreases and becomes equal to or less than a threshold value. For example, it may be the time when the accelerator stroke amount decreases and reaches zero. Alternatively, for example, the start time t1 may be the time when the accelerator stroke amount starts to decrease. Alternatively, for example, the end time t2 of the accelerator-off time Tc may be the time when the accelerator stroke amount increases and becomes greater than a threshold value. For example, it may be the time when the accelerator stroke amount increases and becomes greater than zero. Alternatively, for example, the end time t2 may be the time when the accelerator stroke amount starts to increase.

[0021] For example, the acceleration intention determination unit 30 may cause the timer 31 to start measuring the accelerator off time Tc at a start time t1 when it detects a change in state from the accelerator pedal 10 being depressed to the accelerator off state (e.g., a change in state from the accelerator pedal 10 being depressed to the accelerator not being depressed). After the start time t1, the acceleration intention determination unit 30 may read the time measurement result of the timer 31 at an end time t2 when it detects a change in state from the accelerator off state to the accelerator not being depressed (e.g., a change in state from the accelerator not being depressed to the accelerator pedal 10 being depressed), thereby obtaining the accelerator off time Tc = t2 - t1.

[0022] The acceleration intention determination unit 30 determines whether the accelerator pedal 10 has changed from a depressed state to a state where the accelerator pedal 10 is momentarily released and then re-depressed. For example, the acceleration intention determination unit 30 may determine whether the accelerator release is momentary based on the length of the accelerator-off time Tc. For example, the acceleration intention determination unit 30 may determine that the accelerator release is momentary if the accelerator-off time Tc is within a predetermined time T1, and may determine that the accelerator release is not momentary if the accelerator-off time Tc is longer than the predetermined time T1. For example, the predetermined time T1 may be set based on the general (or standard) time required to change from the accelerator pedal 10 to the brake pedal 12. The predetermined time T1 may be, for example, one second.

[0023] If the acceleration intention determination unit 30 determines that the accelerator pedal 10 has changed back to a depressed state after a momentary accelerator release, it determines that it is unclear whether the driver's depression of the accelerator pedal 10 (i.e., accelerator operation) that began at the end time t2 of the accelerator release is an operation with the driver's intention to accelerate. That is, it determines that it is unclear whether the driver intends to accelerate. On the other hand, if the acceleration intention determination unit 30 determines that the accelerator pedal 10 has changed back to a depressed state after a non-momentary accelerator release, it determines that the depression of the accelerator pedal 10 that began at the end time t2 is an operation with the driver's intention to accelerate. That is, it determines that the driver intends to accelerate.

[0024] If it is determined that the driver's intention to accelerate is unclear, the warning generation unit 32 generates a warning (hereinafter referred to as a "push-misapplication warning") to notify the driver that there is a possibility that the accelerator pedal 10 has been mistaken for the brake pedal 12. The warning generation unit 32 outputs the push-misapplication warning to the driver from the HMI 21 and / or the pedal actuator 22. For example, the push-misapplication warning may be a visual message, an auditory message, an alarm sound, or the illumination of a warning lamp. Furthermore, for example, the warning generation unit 32 may activate the pedal actuator 22 to vibrate the accelerator pedal 10 as a push-misapplication warning, or may generate a pedal reaction force that pushes back the accelerator pedal 10 that the driver is pressing.

[0025] Conversely, if it is determined that the driver intends to accelerate, the warning generation unit 32 does not generate a warning for misapplication of pressure. Note that if the driver changes from depressing the brake pedal 12 to depressing the accelerator pedal 10, the driver's intention to accelerate can be estimated. Therefore, in this case, the warning generation unit 32 does not need to generate a warning for misapplication of pressure. For example, if the driver changes from depressing the brake pedal 12 to depressing the accelerator pedal 10 while the accelerator is off, the warning generation unit 32 does not need to generate a warning for misapplication of pressure.

[0026] Furthermore, misapplication of the accelerator pedal 10 and the brake pedal 12 is likely to occur when the vehicle speed V is low and is unlikely to occur when the vehicle speed V is high. For this reason, the warning generation unit 32 may generate a misapplication warning when the vehicle speed V when the accelerator pedal 10 is pressed again after a momentary accelerator release is equal to or lower than a predetermined speed Vth, and may not generate a misapplication warning when the vehicle speed V when the accelerator pedal 10 is pressed again after a momentary accelerator release is higher than the predetermined speed Vth. For example, the predetermined speed Vth may be set based on a speed range where misapplication of the accelerator pedal 10 and the brake pedal 12 is common. The predetermined speed Vth may be 20 km / h.

[0027] The time (timing) t3 at which the warning generation unit 32 starts outputting a pedal misapplication warning when it is determined that the driver's intention to accelerate is unclear may be variably controlled. For example, the time interval Δt1 from the end time t2 of accelerator release to the time t3 at which the warning generation unit 32 starts outputting a pedal misapplication warning may be variably controlled. For example, the output of the pedal misapplication warning may be started earlier when the accelerator off time Tc is short than when it is long (i.e., the time interval Δt1 may be shorter when the accelerator off time Tc is short than when it is long). For example, the shorter the accelerator off time Tc, the earlier the output of the pedal misapplication warning may be started (i.e., the shorter the accelerator off time Tc, the shorter the time interval Δt1).

[0028] Furthermore, for example, if it is determined that the driver's intention to accelerate is unclear, the output of the erroneous pedal warning may be initiated earlier if the operation speed of the accelerator pedal 10, which began at the end time t2 of the accelerator release, is high than if the operation speed is low (the time interval Δt1 may be made shorter if the operation speed is high than if the operation speed is low). For example, the output of the erroneous pedal warning may be initiated earlier the higher the operation speed (i.e., the higher the operation speed, the shorter the time interval Δt1 may be).

[0029] In addition, for example, the warning generation unit 32 may variably control the intensity of the pedal misapplication warning. For example, the warning generation unit 32 may change the intensity of the pedal misapplication warning by changing the size or intensity of the stimulus (visual stimulus, auditory stimulus, tactile stimulus) output as the pedal misapplication warning without changing the type of stimulus. For example, the intensity of the pedal misapplication warning may be changed by changing the size, brightness, or saturation of the visual message displayed on the display device of the HMI 21. In addition, for example, the intensity of the pedal misapplication warning may be changed by changing the illuminance of the light of the warning lamp.

[0030] The intensity of the pedal misapplication warning may also be changed by, for example, changing the volume or pitch (frequency) of the auditory message or warning sound output from the speaker or buzzer of the HMI 21. The intensity of the pedal misapplication warning may also be changed by, for example, changing the magnitude of the vibration or pedal reaction force applied to the accelerator pedal 10 by the pedal actuator 22. The warning generation unit 32 may also change the intensity of the pedal misapplication warning by changing the type of stimulus output as the pedal misapplication warning. For example, the warning generation unit 32 may change the intensity of the pedal misapplication warning by changing the type of stimulus output as the pedal misapplication warning between at least two of a visual stimulus, an auditory stimulus, and a tactile stimulus.

[0031] For example, the alarm generation unit 32 may output a visual message or turn on a warning lamp as a relatively weak mis-pedal alarm, generate vibration of the accelerator pedal 10 or pedal reaction force as a tactile stimulus as a relatively strong mis-pedal alarm, or output an auditory message or alarm sound as an auditory stimulus as a medium-strength mis-pedal alarm.

[0032] For example, the warning generation unit 32 may output a stronger pedal misapplication warning when the accelerator off time Tc is short than when it is long. For example, the shorter the accelerator off time Tc, the stronger the pedal misapplication warning may be output. For example, the shorter the accelerator off time Tc, the stronger the pedal misapplication warning may be output. Furthermore, for example, the warning generation unit 32 may output a stronger pedal misapplication warning when the operating speed of the accelerator pedal 10 starting from the end time t2 of the accelerator release is high than when it is low. For example, the higher the operating speed, the stronger the pedal misapplication warning may be output.

[0033] Furthermore, for example, the acceleration intention determination unit 30 may variably control the predetermined time T1, which is a threshold for determining whether the accelerator release is momentary. For example, the predetermined time T1 may be set according to the frequency at which it is determined that the driver's intention to accelerate is unclear (i.e., the frequency at which it is determined that the accelerator pedal 10 is pressed again after a momentary accelerator release). For example, the predetermined time T1 may be shortened when the frequency is high compared to when it is low. For example, the acceleration intention determination unit 30 may set the predetermined time T1 to be shorter when the frequency is equal to or greater than a threshold than when it is less than the threshold.

[0034] As a result, if the frequency of determining whether the driver intends to accelerate is unclear is high, the predetermined time T1 is set to a short time, making it less likely that the driver's intention to accelerate is unclear. As a result, it is possible to make it less likely that a pedal misapplication warning will be output. As a result, it is possible to reduce the likelihood of a pedal misapplication warning being output in cases where the driver frequently switches between depressing and releasing the accelerator pedal 10 to adjust speed or when driving in traffic jams. Note that a switch or other operator connected to the HMI 21 may also be used to suppress the pedal misapplication warning.

[0035] For example, the acceleration intention determination unit 30 may count the number of times it is determined that the driver's intention to accelerate is unclear (i.e., the number of times it is determined that the accelerator pedal 10 is pressed down again after a momentary accelerator release). If the number of times it is determined that the driver's intention to accelerate is unclear during the period between the current time and a predetermined first time before the current time is equal to or greater than a threshold, the predetermined time T1 may be shortened. For example, the predetermined time T1 may be shortened to a time shorter than an initial value (fixed value). On the other hand, if the number of times it is determined that the driver's intention to accelerate is unclear during the period between the current time and a predetermined second time before the current time is less than a threshold, the predetermined time T1 may be extended. For example, the predetermined time T1 may be extended to the initial value (fixed value). The second time may be the same length as the first time or may be different from the first time (e.g., the second time may be longer or shorter than the first time), thereby providing hysteresis between the condition for shortening and the condition for extending the predetermined time T1.

[0036] For example, the acceleration intention determination unit 30 may count the number of times at any timing or period that it is determined that the driver has the intention to accelerate, measure the driving time of the vehicle 1, and calculate the frequency at which it is determined that the driver has the intention to accelerate by dividing the number of times that it is determined that the driver has the intention to accelerate by the driving time, and may shorten the specified time T1 when the calculated frequency is high more than when it is low.

[0037] Next, the operation of the accelerator pedal operation warning device of the first embodiment will be described. FIG. 3(a) is a schematic diagram of the warning generation timing of the conventional technology when a pedal misapplication occurs, and FIG. 3(b) is a schematic diagram of the operation of the accelerator pedal operation warning device of the first embodiment. As shown in FIG. 3(a), the conventional technology outputs a warning at time tx when the accelerator pedal depression amount reaches or exceeds a predetermined depression amount A1. However, because the vehicle speed has already increased at this point, the driver may panic at the unintended acceleration and be unable to remove his or her foot from the accelerator pedal 10. Furthermore, a warning may also be erroneously output when the accelerator pedal 10 is depressed too hard, for example, on an uphill slope.

[0038] In contrast, the accelerator pedal operation warning device of the present embodiment outputs a mis-depression warning when the accelerator pedal 10 is depressed again after a short accelerator-off time Tc≦T1 (time t3), as shown in FIG. 3(b).

[0039] Pedal misapplication is most likely to occur in an emergency situation. In an emergency situation, attention resources are insufficient, and even though the pedal next to the foot is the accelerator pedal 10, the driver may mistakenly press it for the brake pedal 12. This is one of the causes of pedal misapplication, and it is more likely to occur in elderly people who have fewer attention resources. For this reason, if a situation arises in which the driver takes their foot off the accelerator pedal 10 for a moment and then tries to press the accelerator pedal 10 again from this state, the system assumes that the driver is hastily trying to switch from the accelerator pedal 10 to the brake pedal 12, and outputs a pedal misapplication warning. This allows the driver to realize that they have misapplication before they press the accelerator pedal 10 too hard, and to switch to the brake pedal 12.

[0040] (Operation) Figure 4 is a flowchart of an example of the accelerator pedal operation warning method of the first embodiment. In step S1, the acceleration intention determination unit 30 determines whether the accelerator pedal 10 is depressed. If the accelerator pedal 10 is depressed (step S1: Y), the process proceeds to step S2. If the accelerator pedal 10 is not depressed (step S1: N), the process returns to step S1. In step S2, the acceleration intention determination unit 30 determines whether the accelerator pedal 10 is in an accelerator-off state. If the accelerator pedal 10 is in an accelerator-off state (step S2: Y), the process proceeds to step S3. If the accelerator pedal 10 is not in an accelerator-off state (step S2: N), the process returns to step S1.

[0041] In step S3, the acceleration intention determination unit 30 determines whether the vehicle speed V is equal to or less than a predetermined speed Vth. If the vehicle speed V is equal to or less than the predetermined speed Vth (step S3: Y), the process proceeds to step S4. If the vehicle speed V is not equal to or less than the predetermined speed Vth (step S3: N), the process returns to step S1. In step S4, the acceleration intention determination unit 30 causes the timer 31 to start measuring the accelerator-off time Tc. In step S5, the acceleration intention determination unit 30 determines whether the accelerator pedal 10 is depressed (whether the accelerator-off state has ended). If the accelerator pedal 10 is depressed (step S5: Y), the process proceeds to step S6. If the accelerator pedal 10 is not depressed (step S5: N), the process proceeds to step S9.

[0042] In step S6, the acceleration intention determination unit 30 determines whether the accelerator off time Tc is equal to or less than a predetermined time T1. If the accelerator off time Tc is equal to or less than the predetermined time T1 (step S6: Y), the acceleration intention determination unit 30 determines that it is unclear whether the depression of the accelerator pedal 10 detected in step S5 is an operation with the driver's intention to accelerate. Then, the process proceeds to step S7. If the accelerator off time Tc is not equal to or less than the predetermined time T1 (step S6: N), the acceleration intention determination unit 30 determines that the depression of the accelerator pedal 10 detected in step S5 is an operation with the driver's intention to accelerate. Then, the process proceeds to step S8.

[0043] In step S7, the warning generation unit 32 outputs a pedal misapplication warning to the driver. The process then proceeds to step S8. In step S8, the acceleration intention determination unit 30 stops the timer 31 from timing the accelerator-off time Tc. The process then ends. If it is determined in step S5 that the accelerator pedal 10 is not depressed (step S5: N), the acceleration intention determination unit 30 determines in step S9 whether the brake pedal 12 is depressed. If the brake pedal 12 is depressed (step S9: Y), the process proceeds to step S8. If the brake pedal 12 is not depressed (step S9: N), the process returns to step S5.

[0044] Second Embodiment When the accelerator pedal 10 is pressed again after a momentary accelerator release, the controller 23 of the second embodiment determines that the driver's intention to accelerate is unclear and suppresses vehicle acceleration based on the depression of the accelerator pedal 10. This allows early detection of an accelerator operation in which the driver's intention to accelerate is unclear and suppresses acceleration of the vehicle 1, allowing the driver to recover from mistaking the accelerator pedal 10 for the brake pedal 12 before strongly depressing the accelerator pedal 10. FIG. 5 is a block diagram of an example of the functional configuration of the controller 23 of the second embodiment. The controller 23 of the second embodiment has a configuration similar to that of the controller 23 of the first embodiment, and the same or similar components are designated by the same reference numerals. The controller 23 includes an acceleration suppression unit 33.

[0045] When the accelerator pedal 10 is depressed again after a momentary accelerator release, the acceleration suppression unit 33 suppresses acceleration of the vehicle 1 caused by depression of the accelerator pedal 10 starting from the end time t2 of the accelerator release, thereby preventing a sudden start or sudden acceleration of the vehicle 1. Note that in the following description, the control that suppresses acceleration of the vehicle 1 caused by depression of the accelerator pedal 10 starting from the end time t2 of the accelerator release when the accelerator pedal 10 is depressed again after a momentary accelerator release may be referred to as "acceleration suppression control."

[0046] For example, acceleration suppression unit 33 may output an acceleration prohibition signal to braking / driving force controller 14 to reduce or set to zero the driving torque generated by driving force source 16. When receiving the acceleration prohibition signal, braking / driving force controller 14 may reduce the driving torque command value to be output to power controller 15 to a value smaller than the driving torque command value determined based on the accelerator stroke amount, or set it to zero.

[0047] Furthermore, for example, the acceleration suppression unit 33 may output an automatic deceleration signal to the braking / driving force controller 14 to cause the brake device 18 to generate a braking torque or increase the braking torque. When the automatic deceleration signal is received, the braking / driving force controller 14 sets the friction braking torque command value to be output to the brake controller 17 and the regenerative braking torque command value to be output to the power controller 15 to a value greater than 0, or increases them to a value greater than the friction braking torque command value determined based on the brake stroke amount or the regenerative braking torque command value determined based on the accelerator stroke amount. Note that the acceleration suppression unit 33 may be configured so that the implementation of the acceleration suppression control can be suppressed by an operator such as a switch also received by the HMI 21.

[0048] Conversely, if it is determined that the driver intends to accelerate, the acceleration suppression unit 33 does not perform the acceleration suppression control. In this case, the braking / driving force controller 14 performs acceleration control based on the accelerator pedal depression operation. For example, the braking / driving force controller 14 performs control to accelerate the vehicle 1 with a driving torque determined based on the accelerator stroke amount. If the driver changes from a state in which he / she depresses the brake pedal 12 to a state in which he / she depresses the accelerator pedal 10, the driver's intention to accelerate can be estimated. Therefore, in this case, it is not necessary to perform the acceleration suppression control. For example, if the state in which he / she depresses the brake pedal 12 to a state in which he / she depresses the accelerator pedal 10 while the accelerator is off, it is not necessary to perform the acceleration suppression control.

[0049] In addition, the acceleration suppression unit 33 performs acceleration suppression control if the vehicle speed V when the accelerator pedal 10 is pressed again after a momentary accelerator release is equal to or less than a predetermined speed Vth, and does not need to perform acceleration suppression control if the vehicle speed V is higher than the predetermined speed Vth even when the accelerator pedal 10 is pressed again after a momentary accelerator release.

[0050] The time (timing) t4 at which the acceleration suppression unit 33 starts the acceleration suppression control when it is determined that the driver's intention to accelerate is unclear may be variably controlled. That is, the time interval Δt2 from the end time t2 of the accelerator release to the time t4 at which the acceleration suppression unit 33 starts the acceleration suppression control may be variably controlled. For example, the acceleration suppression control may be started earlier when the accelerator off time Tc is short than when it is long (that is, the time interval Δt2 may be made shorter when the accelerator off time Tc is short than when it is long). For example, the shorter the accelerator off time Tc is, the earlier the acceleration suppression control may be started (that is, the shorter the accelerator off time Tc is, the shorter the time interval Δt2 may be).

[0051] Furthermore, for example, if it is determined that it is unclear whether the driver intends to accelerate, the acceleration suppression control may be initiated earlier if the operation speed of the accelerator pedal 10, which began at the end time t2 of the accelerator release, is high than if it is low (i.e., the time interval Δt2 may be made shorter if the operation speed is high than if it is low). For example, the higher the operation speed, the earlier the acceleration suppression control may be initiated (i.e., the higher the operation speed, the shorter the time interval Δt2 may be).

[0052] FIG. 6 is a schematic diagram illustrating the operation of the accelerator pedal operation warning device of the second embodiment. The accelerator pedal operation warning device of the second embodiment initiates acceleration suppression control when the accelerator pedal 10 is depressed again after a short accelerator-off time Tc≦T1 (time t4). Missteps are more likely to occur in an emergency situation. In an emergency situation, attentional resources are insufficient, and a driver may mistake the pedal beside the accelerator pedal 10 for the brake pedal 12 and press it down. This is one of the causes of missteps, and is more likely to occur in elderly people with limited attentional resources. Therefore, if a driver momentarily releases their foot from the accelerator pedal 10 and then attempts to re-depress the accelerator pedal 10, the system assumes that the driver is hastily switching from the accelerator pedal 10 to the brake pedal 12, and suppresses vehicle acceleration based on the accelerator pedal 10 depression.

[0053] FIG. 7 is a flowchart of an example of an accelerator pedal operation warning method according to the second embodiment. The processes of steps S11 to S16, S19, and S20 are the same as the processes of steps S1 to S6, S8, and S9 in FIG. 4. If the accelerator-off time Tc is equal to or less than the predetermined time T1 in step S16 (step S16: Y), the process proceeds to step S17. If the accelerator-off time Tc is not equal to or less than the predetermined time T1 (step S16: N), the process proceeds to step S18. In step S17, the acceleration suppression unit 33 performs acceleration suppression control. Thereafter, the process proceeds to step S19. In step S18, the braking / driving force controller 14 performs acceleration control based on the depression of the accelerator pedal. Thereafter, the process proceeds to step S19.

[0054] The first and second embodiments may be combined. That is, when the acceleration intention determination unit 30 determines that the accelerator pedal 10 is pressed again after a momentary accelerator release, the warning generation unit 32 may output a mis-pedal warning, and the acceleration suppression unit 33 may perform acceleration suppression control.

[0055] Effects of the Embodiment (1) The controller 23 determines whether the accelerator pedal 10 has changed from a depressed state to a state in which the accelerator pedal 10 is depressed again after a momentary accelerator release. If the accelerator pedal 10 has changed back to a depressed state after a momentary accelerator release, the controller 23 executes a process to output a pedal misapplication warning to the driver. Alternatively, if the accelerator pedal 10 has changed back to a depressed state after a momentary accelerator release, the controller 23 executes a process to suppress vehicle acceleration based on depression of the accelerator pedal 10. This allows for early detection of accelerator operation, whether or not the driver intends to accelerate, and outputs a pedal misapplication warning to the driver or suppresses acceleration of the vehicle 1 before the vehicle 1 suddenly accelerates. This allows the driver to recover from misapplication of the accelerator pedal 10 instead of the brake pedal 12 before strongly depressing the accelerator pedal 10. If the controller 23 determines that the accelerator pedal 10 has changed back to a depressed state after a momentary accelerator release, the controller 23 may execute both a process to output a warning to the driver and a process to suppress vehicle acceleration based on depression of the accelerator pedal.

[0056] (2) Controller 23 may use timer 31 to measure the duration of the momentary accelerator release. This makes it possible to determine whether depression of accelerator pedal 10 after accelerator release is an operation intended to accelerate. (3) If the state changes from a state in which brake pedal 12 is depressed to a state in which accelerator pedal 10 is depressed during accelerator release, controller 23 may not execute the process of outputting a pedal misapplication warning or the process of suppressing vehicle acceleration based on depression of accelerator pedal 10. This makes it possible to prevent erroneous output of a pedal misapplication warning or suppression of acceleration.

[0057] (4) When the accelerator pedal 10 is depressed again after a momentary accelerator release and the vehicle speed V is higher than the predetermined speed Vth, the controller 23 may not execute the process of outputting a pedal misapplication warning or the process of suppressing acceleration of the vehicle 1 based on depression of the accelerator pedal 10. This prevents erroneous output of a pedal misapplication warning or suppression of acceleration. (5) The controller 23 may output a pedal misapplication warning earlier or output a stronger pedal misapplication warning when the period of momentary accelerator release is short compared to when it is long. Furthermore, the controller 23 may suppress acceleration of the vehicle 1 based on depression of the accelerator pedal 10 earlier when the period of momentary accelerator release is short compared to when it is long. This allows the output of a pedal misapplication warning or acceleration suppression control to be started earlier, or a stronger pedal misapplication warning to be output, in situations with a high degree of urgency.

[0058] (6) Controller 23 may output an earlier pedal misapplication warning or a stronger pedal misapplication warning when the speed at which accelerator pedal 10 is pressed again after a momentary accelerator release is high compared to when it is low. Controller 23 may suppress acceleration of vehicle 1 based on depression of accelerator pedal 10 earlier when the speed at which accelerator pedal 10 is pressed again after a momentary accelerator release is high compared to when it is low. This makes it possible to start outputting a pedal misapplication warning or acceleration suppression control earlier, or to output a stronger pedal misapplication warning, in situations with a high degree of urgency.

[0059] (7) The controller 23 may determine that the accelerator pedal has been momentarily released and then re-depressed if the accelerator-off time Tc from the start time t1 to the end time t2 of the accelerator-off period is within a predetermined time T1. A shorter predetermined time T1 may be set when the temporal frequency of determining that the accelerator pedal has been re-depressed after a momentarily released accelerator is high compared to when the temporal frequency is low. This reduces the likelihood of a pedal misapplication warning being issued or of acceleration suppression control being implemented in cases where the driver frequently switches between depressing and releasing the accelerator pedal 10 to adjust speed or when driving in traffic congestion.

[0060] All examples and conditional terms described herein are intended for educational purposes to aid the reader in understanding the present invention and the concepts provided by the inventor for the advancement of technology, and should be construed without limitation to the specifically described examples and conditions above, and the configuration of examples herein for illustrating the advantages and disadvantages of the present invention. Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the present invention.

[0061] 1...vehicle, 10...accelerator pedal, 11...accelerator sensor, 12...brake pedal, 13...brake sensor, 14...braking / driving force controller, 15...power controller, 16...driving force source, 17...brake controller, 18...braking device, 20...vehicle speed sensor, 21...human machine interface (HMI), 22...pedal actuator, 23...controller, 23a...processor, 23b...storage device, 30...acceleration intention determination unit, 31...timer, 32...alarm generation unit, 33...acceleration suppression unit

Claims

1. A driving assistance method that performs at least one of a process of outputting an alarm to a driver and a process of suppressing acceleration of a vehicle based on an accelerator pedal depression operation, The controller determining whether or not the accelerator stroke amount has increased to greater than 0 or has started to increase after a momentary accelerator release from a depressed state of the accelerator pedal; executes at least one of the processes when it is determined that the accelerator stroke amount has increased to be greater than 0 or has started to increase after the momentary accelerator release. A driving assistance method comprising:

2. 2. The driving assistance method according to claim 1, wherein the method performs both a process of outputting an alert to the driver and a process of suppressing acceleration of the vehicle based on depression of the accelerator pedal, and wherein both processes are executed when it is determined that the accelerator stroke amount has increased to greater than 0 or has started to increase after the momentary accelerator release.

3. 3. The driving assistance method according to claim 1, wherein the duration of the instantaneous accelerator release is measured by a timer.

4. The driving assistance method according to any one of claims 1 to 3, characterized in that, when the state changes from a state in which the brake pedal is depressed to a state in which the accelerator pedal is depressed while the accelerator is released, at least one of the processes is not executed.

5. The driving assistance method according to any one of claims 1 to 4, characterized in that at least one of the processes is not executed if the accelerator stroke amount increases and becomes greater than 0 after the momentary accelerator release, or if the accelerator stroke amount starts to increase but the vehicle speed is higher than a predetermined speed.

6. The driving assistance method according to any one of claims 1 to 5, wherein the method performs processing to output an alarm to the driver, and the alarm is output at an earlier point in time or at a stronger intensity when the period of momentary accelerator release is short compared to when the period of momentary accelerator release is long.

7. 7. The driving assistance method according to claim 1, wherein the method performs processing to suppress acceleration of the vehicle based on depression of the accelerator pedal, and the method suppresses acceleration of the vehicle based on depression of the accelerator pedal at an earlier point in time when the period of the momentary accelerator release is short compared to when the period is long.

8. 8. The driving assistance method according to claim 1, wherein the method performs processing to output a warning to the driver, and the warning is output earlier or stronger when the operation speed at which the accelerator pedal is depressed again after the momentary accelerator release is high compared to when the operation speed is low.

9. 9. The driving assistance method according to claim 1, wherein the method performs processing to suppress acceleration of the vehicle based on depression of the accelerator pedal, and the method suppresses acceleration of the vehicle based on depression of the accelerator pedal at an earlier point in time when the operation speed at which the accelerator pedal is depressed again after the momentary accelerator release is high compared to when the operation speed is low.

10. If the period from the start to the end of the accelerator release is within a predetermined time, it is determined that the accelerator stroke amount has increased to greater than 0 after the momentary accelerator release or that the accelerator stroke amount has started to increase, The driving assistance method according to any one of claims 1 to 9, wherein a shorter predetermined time is set when the temporal frequency at which it is determined that the accelerator stroke amount has increased to greater than 0 or that the accelerator stroke amount has started to increase after the momentary accelerator release is high compared to when the temporal frequency at which it is determined that the accelerator stroke amount has started to increase after the momentary accelerator release is low.

11. A driving assistance device that performs at least one of a process of outputting an alarm to a driver and a process of suppressing acceleration of a vehicle based on an accelerator pedal depression operation, a sensor for detecting the operation of the accelerator pedal; a controller that determines whether an accelerator stroke amount has increased to greater than 0 or has started to increase after a momentary accelerator release from a depressed state of the accelerator pedal, and executes at least one of the processes when it determines that the accelerator stroke amount has increased to greater than 0 or has started to increase after the momentary accelerator release; and A driving assistance device comprising:

12. 11. The driving assistance method according to claim 1, wherein the accelerator release is an operation in which the driver takes his / her foot off the accelerator pedal.

13. 12. The driving support device according to claim 11, wherein the accelerator release is an operation in which the driver takes his / her foot off the accelerator pedal.