Driver assistance systems

Abstract

This system provides a driver assistance system that can accurately estimate the driver's fatigue level by taking into account the state of operation of the accelerator pedal. [Solution] The driver assistance system 1, which assists driving operations according to the driver's fatigue level, comprises an operation state acquisition unit 21 configured to acquire the operation state of the accelerator pedal operated by the driver, and a fatigue level calculation unit 22 configured to calculate the driver's fatigue level C based on the accumulated value of the accelerator pedal depression amount A from the operation state of the accelerator pedal acquired by the operation state acquisition unit 21.

Description

Technical Field

[0001] The present invention relates to a driving support system that supports driving operations according to the degree of fatigue of a vehicle driver.

Background Art

[0002] A driver who drives a vehicle gradually accumulates fatigue as the driving time increases. Therefore, conventionally, a driving support system that supports a driver's driving operation by detecting the driver's fatigue and giving a warning has been known. For example, Patent Document 1 discloses a device that takes fatigue reduction measures such as advising to take a break when the continuous driving time exceeds the allowable driving time. In the device of Patent Document 1, the degree of fatigue is calculated according to the high-fatigue driving time when driving in a high-fatigue area such as a road where the driver is not used to driving, and when the continuous driving time exceeds the allowable driving time changed according to the degree of fatigue, it is determined that it is the timing to take fatigue reduction measures.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the device described in Patent Document 1 mentioned above, the degree of fatigue is calculated according to the driving time spent driving in a high-fatigue area. However, the degree of fatigue estimated from driving time may not accurately reflect the actual fatigue accumulated by the driver. For example, the load on the driver's leg differs depending on whether the driver is lightly pressing the accelerator pedal or pressing it to its maximum extent. This is because the reaction force when the accelerator pedal is pressed generally increases as the amount the accelerator pedal is pressed increases due to the reaction force of the return spring. Therefore, it is desirable to accurately estimate the driver's fatigue level by also considering the driver's operation of the accelerator pedal.

[0005] This invention has been made in view of the above-described circumstances, and its purpose is to provide a driver assistance system that can accurately estimate the driver's fatigue level by taking into account the operation state of the accelerator pedal. [Means for solving the problem]

[0006] According to one aspect of the present invention, a driver assistance system that assists driving operations according to the driver's fatigue level includes an operation state acquisition unit configured to acquire the operation state of the accelerator pedal operated by the driver, and a fatigue level calculation unit configured to calculate the driver's fatigue level by accumulating the amount of depression of the accelerator pedal from the operation state of the accelerator pedal acquired by the operation state acquisition unit and based on the accumulated value of the depression amount. [Effects of the Invention]

[0007] The driver assistance system according to the present invention can accurately estimate the driver's fatigue level by taking into account the operation state of the accelerator pedal. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a block diagram showing a schematic configuration of a driver assistance system in a first embodiment of the present invention. [Figure 2]Figure 2 shows an example of the time-dependent changes in accelerator pedal depression and fatigue level. [Figure 3] Figure 3 is a flowchart showing the flow of driver assistance control in the first embodiment. [Figure 4] Figure 4 is a block diagram showing the schematic configuration of the driver assistance system in a second embodiment of the present invention. [Figure 5] Figure 5 shows an example of the time-dependent changes in accelerator pedal depression, brake pedal depression, and fatigue level. [Figure 6] Figure 6 is a flowchart showing the flow of driver assistance control in the second embodiment. [Figure 7] Figure 7 is a flowchart showing the flow of driver assistance control in the third embodiment. [Modes for carrying out the invention]

[0009] -First Embodiment- Hereinafter, a driver assistance system according to the first embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 is a block diagram showing the schematic configuration of the driver assistance system in this embodiment. As shown in Figure 1, the driver assistance system 1 includes an accelerator pedal sensor 11, a fatigue estimation device 20, a driver assistance controller 30, and a notification device 40, etc. The driver assistance system 1 according to this embodiment is configured to support the driver's driving operations with the driver assistance controller 30 based on the degree of fatigue of the vehicle driver calculated by the fatigue estimation device 20.

[0010] The accelerator pedal sensor 11 is located on the accelerator pedal (not shown) and detects the amount of depression the accelerator pedal is pressed by the driver. The amount of depression detected by the accelerator pedal sensor 11 is input to the fatigue estimation device 20.

[0011] The fatigue estimation device 20 is composed of a computer that includes, for example, a ROM for storing programs and data, a CPU for performing calculations, a RAM for storing dynamic data and calculation results, and an input / output interface. The fatigue estimation device 20 is configured to perform the functions of the operation state acquisition unit 21 and the fatigue level calculation unit 22 to estimate the fatigue level of the driver operating the vehicle. The estimation of fatigue level by the fatigue estimation device 20 will be described later.

[0012] The driver assistance controller 30 is composed of a computer that includes, for example, a ROM for storing programs and data, a CPU for performing calculations, a RAM for storing dynamic data and calculation results, and an input / output interface. The driver assistance controller 30 is configured to support the driver's driving operations according to the driver's fatigue level input from the fatigue estimation device 20. The support for driving operations includes, for example, at least one of notifying the driver and controlling the vehicle's speed.

[0013] The driver assistance controller 30, when the driver's fatigue level is high, notifies the driver, for example, through the notification device 40, to make the driver aware of the increasing fatigue and encourage the driver to rest. The driver assistance controller 30 may also be configured to control a drive unit and / or braking unit (not shown) to perform speed reduction control when the driver's fatigue level is high. As speed reduction control, for example, a speed limiter function that controls the driving force so that the vehicle speed does not exceed the upper speed limit may be used. By performing speed reduction control when the driver's fatigue level is high, it is possible to prevent the vehicle speed from increasing more than necessary and to support the driver's driving operation.

[0014] The notification device 40 is configured to provide notifications to the driver in response to commands from the driver assistance controller 30. The notification device 40 has, for example, a display, indicator lights, speakers, etc., located on the instrument panel at the front of the vehicle, and provides information to the driver through sight and / or hearing. The notification device 40 may also be configured to provide notifications through touch, for example.

[0015] The following describes in detail how the fatigue level of a driver is estimated by the fatigue estimation device 20. Drivers gradually accumulate fatigue as their driving time increases. However, the fatigue a driver actually feels is influenced not only by the length of driving time but also by vehicle characteristics and other factors. For example, focusing on the structure of the accelerator pedal, the load on the driver's leg differs depending on whether the driver is lightly pressing the accelerator pedal or pressing it to its maximum extent. This is because the reaction force when the accelerator pedal is pressed generally increases as the amount the accelerator pedal is pressed increases, due to the reaction force of the return spring.

[0016] Generally, the amount of accelerator pedal depression required to maintain the same speed differs between vehicles with larger and smaller engine displacements. To maintain a certain speed, a vehicle with a smaller engine displacement requires a greater accelerator pedal depression compared to a vehicle with a larger engine displacement. Therefore, for example, even if the vehicle speed and driving time are the same, driving a vehicle with a smaller engine displacement requires a greater accelerator pedal depression than driving a vehicle with a larger engine displacement, and the load on the driver's leg tends to be greater. Also, for example, even if the driving time is the same, driving at high speeds requires a greater accelerator pedal depression than driving at low speeds, so the load on the driver's leg tends to be greater when driving at high speeds.

[0017] Therefore, the fatigue estimation device 20 in the present embodiment focuses on vehicle characteristics that affect the driver's fatigue, such as the operating reaction force of the accelerator pedal, and is configured to accurately estimate the degree of fatigue actually felt by the driver in consideration of the operating state of the accelerator pedal by the driver.

[0018] The operation state acquisition unit 21 of the fatigue estimation device 20 acquires the accelerator pedal depression amount A detected by the accelerator pedal sensor 11 as the operation state of the accelerator pedal. The accelerator pedal depression amount A indicates 100% when the accelerator pedal is fully depressed, and indicates 0% when the accelerator pedal is released, that is, when the accelerator pedal is not depressed. The operation state acquisition unit 21 can grasp whether the accelerator pedal is depressed or not from the accelerator pedal depression amount A, and can grasp whether the accelerator pedal is being depressed or released from the change in the accelerator pedal depression amount A.

[0019] The fatigue degree calculation unit 22 of the fatigue estimation device 20 calculates the driver's fatigue degree C based on the operation state of the accelerator pedal acquired by the operation state acquisition unit 21. The fatigue degree calculation unit 22, for example, integrates the accelerator pedal depression amount A and calculates the fatigue degree C based on the integrated value of the accelerator pedal depression amount A. The fatigue estimation device 20 calculates the fatigue degree C by, for example, any of the following calculation methods. (1) Integrate the accelerator pedal depression amount A (2) Integrate the accelerator pedal depression amount A with weights (3) Integrate considering the change rate of the accelerator pedal depression amount A Specific examples of the calculation method of the fatigue degree C will be described below.

[0020] (1) Integrate the accelerator pedal depression amount A The fatigue calculation unit 22 non-dimensionalizes the accelerator pedal depression amount A detected by the accelerator pedal sensor 11 and then integrates them. For example, it multiplies the accelerator pedal depression amount A detected by the accelerator pedal sensor 11 at each sampling period by a predetermined conversion coefficient k. Then, by integrating the accelerator pedal depression amount A multiplied by the conversion coefficient k, it calculates the fatigue level C.

[0021] The conversion coefficient k is pre-set appropriately so that it increases as the accelerator pedal depression amount A increases. For example, the conversion coefficient k takes a value of 1 when the accelerator pedal depression amount A is 0%, i.e., when the accelerator pedal is not depressed, and increases in proportion to the increase in accelerator pedal depression amount A, taking a value of 1.1 when the accelerator pedal depression amount A is 100%, i.e., when the accelerator pedal is depressed to its maximum extent. When the accelerator pedal depression amount A is 50%, the conversion coefficient k = 1.05. In this case, the conversion coefficient k is expressed by the following (Equation 1). k=1+(A / 1000) (Formula 1)

[0022] The fatigue calculation unit 22 sets a flag to 1 when the accelerator pedal is depressed and sets a flag to 0 when the accelerator pedal is released. This flag is an ON / OFF flag that represents the ON / OFF state of the accelerator pedal. For example, when the ON / OFF flag is set to 1, the fatigue calculation unit 22 calculates the fatigue model value D (=1×k) by multiplying the above conversion coefficient k by the flag output value = 1. When the ON / OFF flag is set to 0, the fatigue model value D = 0 (=0×k).

[0023] The fatigue model value D corresponds to the amount of accelerator pedal depression A for each sampling period and can be said to represent the degree of fatigue acting on the driver for each sampling period. Hereafter, the fatigue model value D calculated by calculation method (1) may be expressed as D(1). The fatigue level C is calculated by accumulating the fatigue model value D based on the amount of accelerator pedal depression A for each sampling period. In other words, the fatigue level C can be said to represent the degree of accumulation of driver fatigue accumulated by pressing the accelerator pedal.

[0024] Figures 2(a) and 2(b) show examples of the time variation of accelerator pedal depression A and fatigue level C, respectively. As shown in Figure 2(a), the accelerator pedal is depressed at time t1, increases at times t2 and t3, and is released at time t4. Then it is depressed again at time t10, increases at time t11, and is depressed to its maximum extent from time t12 onwards. As shown in Figure 2(b), fatigue level C begins to increase from time t1, and remains constant when the accelerator pedal is released at time t4. Then, when the accelerator pedal is depressed again at time t10, it increases again in accordance with the accelerator pedal depression A. From time t12 onwards, fatigue level C gradually increases.

[0025] If we denote the fatigue model values ​​D corresponding to the accelerator pedal depression amount A at times t1, t2, ..., tn as D_t1, D_t2, ..., D_tn, then the fatigue level C accumulated between time t1 and time tn is expressed by the following (Equation 2). C=D_t1+D_t2+···D_tn···(Formula 2) A higher fatigue level C indicates a greater degree of accumulated fatigue in the driver.

[0026] As shown in Figure 2(b), fatigue level C gradually increases when the accelerator pedal is depressed, and remains constant when the accelerator pedal is released. When the accelerator pedal is depressed to its maximum extent, the load on the driver's leg is greater due to the reaction force of the accelerator pedal compared to when the accelerator pedal is lightly depressed. When driving a vehicle with a small engine displacement and a vehicle with a large engine displacement at the same speed, the accelerator pedal needs to be pressed harder in the vehicle with the small engine displacement than in the vehicle with the large engine displacement. Therefore, for example, when driving a vehicle with a small engine displacement and a vehicle with a large engine displacement at the same speed for the same amount of time, the driver of the vehicle with the small engine displacement tends to accumulate more fatigue. The fatigue level C shown in Figure 2(b) accurately represents the degree of fatigue accumulated in the driver from the perspective of these vehicle characteristics.

[0027] (2) Add weights to the accelerator pedal depression amount A and calculate the sum. The fatigue calculation unit 22 calculates the fatigue level C, taking into account that the load on the driver's legs increases as the accelerator pedal depression amount A increases. The fatigue calculation unit 22 sets a weighting coefficient l that increases as the accelerator pedal depression amount A increases. For example, when the accelerator pedal depression amount A is 30%, l=1.3, when the accelerator pedal depression amount A is 40%, l=1.4, and when the accelerator pedal depression amount A is 50%, l=1.5. In this case, the weighting coefficient l is expressed by the following (Equation 3). l=1+(A / 100) (Formula 3)

[0028] The fatigue calculation unit 22 calculates a fatigue model value D by multiplying the accelerator pedal depression amount A detected by the accelerator pedal sensor 11 at each sampling period by the conversion coefficient k used in the calculation method (1) described above, and also by the weight coefficient l. Hereafter, the fatigue model value D calculated in calculation method (2) may be expressed as D(2). Then, the fatigue level C is calculated by integrating the fatigue model values ​​D. The fatigue model value D(2) calculated here is the value obtained by multiplying the fatigue model value D(1) calculated in calculation method (1) described above by the weight coefficient l. In other words, the fatigue model value D(2) can be said to be a value obtained by correcting the fatigue model value D(1) corresponding to the accelerator pedal depression amount A according to the magnitude of the accelerator pedal depression amount A. As a result, the fatigue level C is calculated as a value that more accurately reflects the load acting on the driver depending on the magnitude of the accelerator pedal depression amount A.

[0029] (3) The calculation is performed by taking into account the rate of change of accelerator pedal depression amount A. During driving, the driver adjusts the vehicle speed by adjusting the amount A of the accelerator pedal depression. The load on the driver's legs tends to increase as the change in the amount A of the accelerator pedal depression increases. Therefore, the fatigue calculation unit 22 calculates the rate of change E of the amount A of the accelerator pedal depression, and calculates the fatigue level C to be greater as the rate of change E increases. Furthermore, the fatigue calculation unit 22 also takes into account the direction of operation of the accelerator pedal when calculating the fatigue level C. Due to the structure of the human leg, the load on the legs is greater and fatigue tends to be greater when releasing the accelerator pedal than when pressing it down. Therefore, the fatigue calculation unit 22 calculates the fatigue level C to be greater when the accelerator pedal is being operated in the release direction than when the accelerator pedal is being pressed down.

[0030] The fatigue calculation unit 22 calculates the rate of change E of the accelerator pedal depression amount A detected by the accelerator pedal sensor 11. The rate of change E (% / s) of the accelerator pedal depression amount A is the change ΔA (%) of the accelerator pedal depression amount A (%) for each sampling period (s). The fatigue calculation unit 22 further sets a weighting coefficient m according to the direction of operation of the accelerator pedal. For example, if the accelerator pedal is being depressed, the fatigue calculation unit 22 sets the weighting coefficient m related to the direction of operation of the accelerator pedal to 1, and if the accelerator pedal is being released, it sets the weighting coefficient m related to the direction of operation of the accelerator pedal to 1.5.

[0031] The fatigue calculation unit 22 calculates a rate of change correction term F using the rate of change E of the accelerator pedal depression amount A and a weighting coefficient m related to the direction of operation of the accelerator pedal. For example, the rate of change correction term F is calculated by multiplying the rate of change E by the weighting coefficient m. In this case, the rate of change correction term F is expressed by the following (Equation 4). F=(E / 100)×m (Formula 4)

[0032] The fatigue calculation unit 22 calculates the fatigue model value D by adding the rate of change correction term F to the fatigue model value D(1) calculated in the calculation method (1) described above (D = D(1) + F). Hereafter, the fatigue model value D calculated in calculation method (3) may be expressed as D(3). Then, the fatigue level C is calculated by integrating the fatigue model values ​​D. The fatigue model value D(3) calculated here is a value obtained by correcting the fatigue model value D(1) calculated in the calculation method (1) described above based on the rate of change E of the accelerator pedal depression amount A and the direction of operation of the accelerator pedal. As a result, the fatigue level C is calculated as a value that reflects the load acting on the driver depending on the speed and direction of operation of the accelerator pedal.

[0033] The fatigue calculation unit 22 may calculate the rate of change correction term F based solely on the rate of change E of the accelerator pedal depression amount A. In this case, the rate of change correction term F is expressed as, for example, F = E / 100.

[0034] The fatigue level estimation process in this embodiment will be described in detail below using the flowchart in Figure 3. Figure 4 is a flowchart showing the flow of the driving support control, including the fatigue level estimation process in this embodiment. The process shown in Figure 3 is mainly performed periodically by the fatigue estimation device 20.

[0035] In step S101, if the ignition switch ON signal is received from an ignition switch (not shown), in step S102 the fatigue estimation device 20 resets the fatigue level C stored in the memory (not shown).

[0036] In step S103, the operation state acquisition unit 21 acquires the accelerator pedal depression amount A detected by the accelerator pedal sensor 11 as the operation state of the accelerator pedal.

[0037] In step S104, the fatigue calculation unit 22 determines whether the accelerator pedal is being operated based on the accelerator pedal operation state obtained in step S103. If accelerator pedal depression amount A = 0, it is determined that the accelerator pedal is not being operated, and the process proceeds to step S107. If accelerator pedal depression amount A is not 0, it is determined that the accelerator pedal is being operated, and the process proceeds to step S105.

[0038] In step S105, the fatigue calculation unit 22 calculates the fatigue model value D according to one of the calculation methods (1) to (3) described above. In step S106, the fatigue calculation unit 22 calculates the fatigue level C by adding the fatigue model value D calculated in step S105 to the fatigue level C calculated in the previous cycle. The fatigue level C calculated here is stored in memory (not shown).

[0039] In step S107, the fatigue calculation unit 22 determines whether the fatigue level C calculated in step S106 is equal to or greater than a preset threshold ThC. If it is determined in step S104 that the accelerator pedal has not been operated, the fatigue level C calculated in the previous cycle is compared with the threshold ThC. If it is determined that the fatigue level C is equal to or greater than the threshold ThC, the process proceeds to step S108. On the other hand, if it is determined that the fatigue level C is less than the threshold ThC, the process returns to step S103 and continues estimating the fatigue level C.

[0040] In step S108, the fatigue estimation device 20 transmits a signal to the driver support controller 30 indicating that the fatigue level C is equal to or greater than the threshold ThC. The driver support controller 30 controls the notification device 40 to notify the driver in response to the signal from the fatigue estimation device 20. The notification device 40 notifies the driver, for example, by audio output and / or display output, that the driver's fatigue level is increasing and encourages the driver to rest. In addition to notifying the driver, or instead of notifying the driver, the driver support controller 30 may perform, for example, vehicle speed reduction control.

[0041] In step S109, the fatigue estimation device 20 determines whether or not it has received an ignition switch off signal from the ignition switch. If it has not received an ignition switch off signal, it returns to step S103 and continues estimating the fatigue level C and notifying the driver. If it has received an ignition switch off signal, it terminates this process. This concludes the current process.

[0042] The driver assistance system 1 according to this embodiment, as described above, can provide the following effects.

[0043] (1) A driver assistance system that assists driving operations according to the driver's fatigue level includes an operation state acquisition unit 21 configured to acquire the operation state of the accelerator pedal operated by the driver, and a fatigue level calculation unit 22 configured to calculate the driver's fatigue level C based on the accumulated value of the accelerator pedal depression amount A from the operation state of the accelerator pedal acquired by the operation state acquisition unit 21.

[0044] The fatigue calculation unit 22 calculates a fatigue model value D(1) corresponding to the accelerator pedal depression amount A for each sampling period, and calculates the fatigue level C by integrating the fatigue model values ​​D(1). Generally, accelerator pedals are configured such that the reaction force acting on the driver's leg increases as the accelerator pedal depression amount A increases. Therefore, even if the driving time is the same, the load on the driver's leg differs depending on whether the accelerator pedal depression amount A is large or small, and the fatigue level C accumulated by the driver also differs. By calculating the fatigue level C based on the integrated value of the accelerator pedal depression amount A, it is possible to accurately estimate the fatigue level actually felt by the driver, taking into account the driver's operation of the accelerator pedal.

[0045] (2) The fatigue calculation unit 22 sets a weighting coefficient l that increases as the amount of accelerator pedal depression A increases, and calculates an integrated value by multiplying the depression amount A by the weighting coefficient l. For example, the fatigue calculation unit 22 calculates a fatigue model value D(2) by multiplying the fatigue model value D(1) corresponding to the amount of accelerator pedal depression A by the weighting coefficient l, and calculates the fatigue level C by integrating the fatigue model values ​​D(2). The reaction force when operating the accelerator pedal increases as the amount of accelerator pedal depression A increases, and the load on the driver's leg increases. By setting a weighting coefficient l that increases as the amount of accelerator pedal depression A increases, the fatigue level accumulated in the driver due to the reaction force when operating the accelerator pedal can be accurately estimated.

[0046] (3) The fatigue calculation unit 22 calculates the rate of change E of the accelerator pedal depression amount A, and further calculates the fatigue level C using the rate of change E. The load on the driver's legs tends to increase as the change in accelerator pedal depression amount A increases. Therefore, by calculating the fatigue level C considering the rate of change E of accelerator pedal depression amount A, it is possible to accurately estimate the fatigue level accumulated in the driver due to accelerator pedal operation.

[0047] (4) The fatigue calculation unit 22 calculates the fatigue level C to be greater when the rate of change E represents the release operation of the accelerator pedal compared to when the rate of change E represents the depression operation of the accelerator pedal. When a driver operates the accelerator pedal, the release operation places a greater load on the legs and tends to cause more fatigue than the depression operation. Therefore, the fatigue calculation unit 22 sets a weight coefficient m according to the direction of operation of the accelerator pedal, and the weight coefficient m is set to a larger value when the accelerator pedal is in the release operation than when the accelerator pedal is in the depression operation. For example, the fatigue calculation unit 22 calculates a rate of change correction term F based on the rate of change E of the accelerator pedal depression amount A and the weight coefficient m according to the direction of operation of the accelerator pedal, calculates a fatigue model value D(3) by adding the rate of change correction term F to the fatigue model value D(1) corresponding to the accelerator pedal depression amount A, and calculates the fatigue level C by integrating the fatigue model values ​​D(3). This makes it possible to accurately estimate the degree of fatigue accumulated in the driver due to accelerator pedal operation.

[0048] (5) The driving support system 1 further includes a driving support controller (driving support unit) 30 that provides driving support when the fatigue level C calculated by the fatigue level calculation unit 22 is equal to or greater than a predetermined threshold ThC. The driving support provided by the driving support controller 30 includes at least one of notifying the driver by the notification device 40 and controlling the vehicle's speed. This allows for accurate estimation of the driver's fatigue level C, and when the fatigue level C is increasing, it is possible to provide driving support to the driver by alerting the driver and / or controlling the speed.

[0049] -Second Embodiment- The following describes a driver assistance system according to a second embodiment of the present invention. Figure 4 is a block diagram showing the schematic configuration of the driver assistance system in this embodiment. The basic configuration of the driver assistance system according to the second embodiment is the same as that of the driver assistance system 1 of the first embodiment described above. The differences from the first embodiment will be mainly described below.

[0050] Even when the driver is operating the brake pedal, the driver's leg is subjected to a load due to the reaction force of the brake pedal, just as when the driver is operating the accelerator pedal. Furthermore, when the driver switches between the accelerator and brake pedals to adjust the vehicle speed, the driver needs to move their foot between the accelerator and brake pedals, which leads to fatigue. The driver assistance system 1A in this embodiment is configured to estimate the driver's fatigue level by further considering the driver's brake pedal operation.

[0051] As shown in Figure 4, the driver assistance system 1A in this embodiment further includes a brake pedal sensor 12. The brake pedal sensor 12 is located on a brake pedal (not shown) and detects the amount of pressure applied to the brake pedal by the driver. The brake pedal pressure B detected by the brake pedal sensor 12 is input to the fatigue estimation device 20A.

[0052] The brake pedal operation state acquisition unit 23 of the fatigue estimation device 20A acquires the brake pedal depression amount B detected by the brake pedal sensor 12 as the brake pedal operation state. The brake pedal depression amount B indicates 100% when the brake pedal is fully depressed and 0% when the brake pedal is released, i.e., when the brake pedal is not depressed. From the brake pedal depression amount B, the brake pedal operation state acquisition unit 23 can determine whether the brake pedal is depressed or not, and from the change in the brake pedal depression amount B, it can determine whether the brake pedal is depressed or released. Note that the fatigue estimation device 20A may be configured in the operation state acquisition unit 21 to acquire the brake pedal operation state in addition to the accelerator pedal operation state. In this case, the brake pedal operation state acquisition unit can be omitted.

[0053] The fatigue calculation unit 22 calculates the fatigue level C using the brake pedal operation state acquired by the brake pedal operation state acquisition unit 23, in addition to the accelerator pedal operation state. For example, the fatigue calculation unit 22 calculates the fatigue level C by adding the integrated value of the brake pedal depression amount B to the integrated value of the accelerator pedal depression amount A. In other words, the fatigue calculation unit 22 calculates the fatigue level C by integrating the accelerator pedal depression amount A when the accelerator pedal is operated by the driver, and by integrating the brake pedal depression amount B when the brake pedal is operated.

[0054] The fatigue calculation unit 22 calculates a fatigue model value Db corresponding to the brake pedal depression amount B, which is detected by the brake pedal sensor 12 at each sampling period, by multiplying it by a predetermined conversion coefficient n. The conversion coefficient n is set appropriately so that it increases as the brake pedal depression amount B increases, similar to the conversion coefficient k used in the calculation method (1) described above.

[0055] The fatigue calculation unit 22 calculates the fatigue level C by adding the fatigue model value Db corresponding to the brake pedal depression amount B to the fatigue model value D corresponding to the accelerator pedal depression amount A calculated by any of the calculation methods (1) to (3) described above. When calculating the fatigue model value Db corresponding to the brake pedal depression amount B, the fatigue model value Db may also be calculated by weighting the brake pedal depression amount B or taking into account the rate of change of the brake pedal depression amount B, similar to the calculation methods (2) to (3) described for the accelerator pedal depression amount A.

[0056] Figures 5(a) to 5(c) show examples of the time variation of accelerator pedal depression A, brake pedal depression B, and fatigue level C, respectively. As shown in Figure 5(a), the accelerator pedal is depressed at time t1, increases at times t2 and t3, and is released at time t4. Then, as shown in Figure 5(b), the brake pedal is depressed at time t5, increases at time t6, and is released at time t8. After that, the accelerator pedal is depressed again at time t10 and released at time t14, then the brake pedal is depressed again at time t15 and released at time t17. In this way, the accelerator pedal and brake pedal are operated alternately by switching between them.

[0057] As shown in Figure 5(c), fatigue level C begins to increase from time t1 in accordance with the accelerator pedal depression A. When the brake pedal is depressed at time t5, fatigue level C increases in accordance with the brake pedal depression B. Subsequently, fatigue level C increases in accordance with the accelerator pedal depression operation at time t10, and in accordance with the brake pedal depression operation at time t15. As shown in Figure 5(c), fatigue level C gradually increases even when the accelerator pedal is released and the brake pedal is depressed. The fatigue level C shown in Figure 5(c) accurately represents the fatigue accumulated in the driver, taking into account the load on the driver's legs due to the operation of depressing the brake pedal, and the fatigue caused by switching between the accelerator and brake pedals.

[0058] The fatigue level estimation process in this embodiment will be described in detail below using the flowchart in Figure 6. Figure 6 is a flowchart showing the flow of the driving support control, including the fatigue level estimation process in this embodiment. The process shown in Figure 6 is mainly performed periodically by the fatigue estimation device 20A. The processes in steps S101 to S109 of the flowchart in Figure 6 are the same as the processes in steps S101 to S109 of the flowchart in Figure 3, so a detailed explanation will be omitted.

[0059] In step S103, the operation state acquisition unit 21 acquires the accelerator pedal depression amount A detected by the accelerator pedal sensor 11 as the operation state of the accelerator pedal. Furthermore, the brake pedal operation state acquisition unit 23 acquires the brake pedal depression amount B detected by the brake pedal sensor 12 as the operation state of the brake pedal.

[0060] In step S104, the fatigue calculation unit 22 determines whether the accelerator pedal is being operated based on the operation state of the accelerator pedal obtained in step S103. If it is determined that the accelerator pedal is being operated, the process proceeds to step S105; if it is determined that the accelerator pedal is not being operated, the process proceeds to step S201.

[0061] In step S201, the fatigue calculation unit 22 determines whether the brake pedal is being operated based on the brake pedal operation state obtained in step S103. If the brake pedal depression amount B = 0, it is determined that the brake pedal is not being operated, and the process proceeds to step S107. If the brake pedal depression amount B is not 0, it is determined that the brake pedal is being operated, and the process proceeds to step S202.

[0062] In step S202, the fatigue calculation unit 22 calculates a fatigue model value Db corresponding to the brake pedal depression amount B, as described above. In step S106, the fatigue calculation unit 22 calculates the fatigue level C by adding the fatigue model value D corresponding to the accelerator pedal depression amount A calculated in step S105, or the fatigue model value Db corresponding to the brake pedal depression amount B calculated in step S202, to the fatigue level C calculated in the previous cycle. The fatigue level C calculated here is stored in a memory (not shown).

[0063] In the second embodiment described above, in addition to the effects and advantages of the first embodiment described above, the following effects and advantages can be achieved.

[0064] The driver assistance system 1A further includes a brake pedal operation state acquisition unit 23 configured to acquire the operation state of the brake pedal operated by the driver. The fatigue level calculation unit 22 further uses the brake pedal operation state acquired by the brake pedal operation state acquisition unit 23 to calculate the fatigue level C. Even when the accelerator pedal is not being operated, if the driver is operating the brake pedal, the driver's legs are subjected to a load due to the reaction force of the brake pedal, and fatigue accumulates. Therefore, by taking the brake pedal operation state into account when calculating the fatigue level C, the accuracy of the fatigue level C estimation can be improved.

[0065] -Third Embodiment- The following describes a driver assistance system according to a third embodiment of the present invention. The basic configuration of the driver assistance system according to the third embodiment is the same as that of the driver assistance system 1A of the second embodiment described above. The following mainly describes the differences from the first and second embodiments.

[0066] When a vehicle is traveling on a congested road, the driver needs to frequently switch between the accelerator and brake pedals to adjust the vehicle speed, which tends to lead to driver fatigue. Therefore, in the driver assistance system 1A of this embodiment, when the vehicle is traveling on a congested road, a correction element G representing driver fatigue caused by the congestion is set, and the fatigue level C is calculated taking the correction element G into account.

[0067] The fatigue estimation device 20A is configured to acquire traffic congestion information for the road the vehicle is traveling on by receiving traffic congestion information distributed from, for example, a VICS (registered trademark) center. The fatigue estimation device 20A may also recognize whether traffic congestion is occurring based on image data of the area in front of the vehicle captured by an imaging device (not shown).

[0068] If traffic congestion occurs on the road the vehicle is traveling on, the fatigue calculation unit 22 sets a correction element G based on, for example, the operating state of the brake pedal or the operating state of the accelerator pedal. The fatigue calculation unit 22 sets, for example, the fatigue model value Db corresponding to the brake pedal depression amount B described in the second embodiment above as the correction element G.

[0069] The fatigue calculation unit 22 may set the number of times the accelerator pedal is pressed as a correction element G. In this case, the fatigue calculation unit 22 sets the correction element G such that the fatigue level C increases as the number of times the accelerator pedal is pressed increases. For example, when the output value of the ON / OFF flag described in the first embodiment above changes from 0 to 1, the fatigue calculation unit 22 determines that the accelerator pedal has been pressed and sets the correction element G to a predetermined value (for example, G=0.1). As a result, each time the accelerator pedal is pressed from a released state, the correction element G is added to the fatigue level C, and the fatigue level C increases as the number of times the accelerator pedal is pressed increases. If the output value of the ON / OFF flag does not change from 0 to 1, the correction element G is set to 0.

[0070] The fatigue level estimation process in this embodiment will be described in detail below using the flowchart in Figure 7. Figure 7 is a flowchart showing the flow of the driving support control including the fatigue level estimation process in this embodiment. The process shown in Figure 7 is mainly performed periodically by the fatigue estimation device 20A. The process in steps S101 to S109 of the flowchart in Figure 7 is the same as the process in steps S101 to S109 of the flowchart in Figure 6, so a detailed explanation will be omitted.

[0071] In step S104, the fatigue calculation unit 22 determines whether the accelerator pedal is being operated based on the operation state of the accelerator pedal obtained in step S103. If it is determined that the accelerator pedal is being operated, the process proceeds to step S105; if it is determined that the accelerator pedal is not being operated, the process proceeds to step S301.

[0072] In step S301, traffic congestion information is obtained, and it is determined whether the road the vehicle is traveling on is congested or not. If it is determined that the road is congested, the process proceeds to step S302; if it is determined that the road is not congested, the process proceeds to step S106.

[0073] In step S302, the fatigue calculation unit 22 sets a correction element G based on the operating state of the brake pedal or the accelerator pedal. If it is determined in step S104 that the accelerator pedal is being operated, a correction element G based on the number of times the accelerator pedal has been pressed is set. On the other hand, if it is determined in step S104 that the accelerator pedal is not being operated, a correction element G based on the operating state of the brake pedal is set.

[0074] In step S106, the fatigue calculation unit 22 calculates the fatigue level C by adding the fatigue model value D corresponding to the accelerator pedal depression amount A calculated in step S105, and / or the correction element G calculated in step S302, to the fatigue level C calculated in the previous cycle. The fatigue level C calculated here is stored in a memory (not shown).

[0075] In the third embodiment described above, in addition to the effects and advantages of the first and second embodiments described above, the following effects and advantages can be achieved.

[0076] (1) The fatigue calculation unit 22 sets a correction element G when the road on which the vehicle is traveling is congested, and calculates the fatigue level C taking the correction element G into account. When driving on a congested road, fatigue accumulates in the driver even at low speeds. Therefore, by calculating the fatigue level C to be larger by taking the correction element G into account during congestion, the accuracy of the fatigue level C estimation can be improved by taking into account the fatigue accumulated in the driver during congestion.

[0077] (2) The fatigue calculation unit 22 sets a correction element G based on at least one of the operating state of the brake pedal operated by the driver and the number of times the accelerator pedal is pressed. When driving on a congested road, the driver frequently switches between pressing the accelerator pedal and the brake pedal to adjust the vehicle speed, so fatigue tends to accumulate in the driver's legs. Therefore, by calculating the fatigue level C to be larger by taking the correction element G into account during traffic congestion, the accuracy of estimating the fatigue level C can be improved by taking into account the load placed on the driver by frequent pedal operation.

[0078] (3) The fatigue calculation unit 22 further calculates the fatigue level C using the number of times the accelerator pedal is pressed. Since the fatigue accumulated in the driver tends to increase with the number of times the accelerator pedal is pressed from the released state, the accuracy of estimating the fatigue level C can be improved by considering the number of times the accelerator pedal is pressed.

[0079] -Variations- (1) In the above-described embodiment, an ON / OFF flag was set according to the operation state of the accelerator pedal, and the fatigue model value D was calculated by multiplying the flag output value (1 or 0) by a conversion coefficient k (k = 1 to 1.1). However, the fatigue model value D is not limited to this, and can be calculated by various methods. For example, the conversion coefficient k may be set to increase from 0 to 0.1 in accordance with the increase in accelerator pedal depression amount A, and the fatigue model value D may be calculated by adding the conversion coefficient k to the output value of the ON / OFF flag according to the operation state of the accelerator pedal.

[0080] (2) In the flowchart of Figure 3 of the first embodiment, if it is determined in step S104 that the accelerator pedal is not being operated, the process proceeds to step S107, where the fatigue level C calculated in the previous cycle is compared with the threshold ThC. However, this is not limited to this, and for example, even if it is determined in step S104 that the accelerator pedal is not being operated, the process may be configured to proceed to step S105 and calculate the fatigue model value D. As described above, if the accelerator pedal is not being operated, the flag output value of the ON / OFF flag is 0, and the fatigue model value D is 0. Therefore, the fatigue level C calculated in the current cycle will be the same value as the fatigue level C calculated in the previous cycle. Thus, the method for estimating the fatigue level C in the fatigue estimation device 20 is not limited to the one described using the flowchart of Figure 3 above, and various modifications are possible.

[0081] (3) In the above-described embodiment, an example was described in which a fatigue model value D is calculated for each sampling period of the accelerator pedal sensor 11, and the fatigue level C is calculated by integrating the fatigue model values ​​D. However, the calculation period for the fatigue model value D and the fatigue level C may be longer than the sampling period. This can reduce the computational load on the fatigue estimation device 20.

[0082] (4) In the third embodiment described above, the correction element G was set based on at least one of the operating state of the brake pedal operated by the driver and the number of times the accelerator pedal was pressed. However, the method of setting the correction element G during traffic congestion is not limited to this. For example, if it is determined that traffic congestion is occurring in step S301 of the flowchart in Figure 7, in step S302, the correction element G may be set to a fixed value (>0) regardless of the operating state of the brake pedal and the number of times the accelerator pedal was pressed. This allows for calculations to be made so that the fatigue level C during traffic congestion is large, taking into account that fatigue tends to accumulate in the driver during traffic congestion.

[0083] Although several embodiments of the present invention have been described above, it should be noted that the present invention is not limited to the above embodiments, and various further modifications and changes are possible within the scope of the present invention. [Explanation of Symbols]

[0084] 1.1A Driver Assistance System 11. Accelerator pedal sensor 12 Brake pedal sensor 20,20A Fatigue Estimation Device 21 Operation status acquisition unit 22 Fatigue level calculation unit 23 Brake pedal operation status acquisition unit 30. Driver assistance controller 40. Notification device

Claims

1. A driver assistance system that assists driving operations according to the driver's fatigue level, An operation state acquisition unit configured to acquire the operation state of the accelerator pedal operated by the aforementioned driver, A fatigue calculation unit is configured to calculate the driver's fatigue level based on the accumulated value of the accumulated value of the accelerator pedal depression, which is obtained from the operating state of the accelerator pedal acquired by the operating state acquisition unit. A driver assistance system equipped with these features.

2. The driver assistance system according to claim 1, wherein the fatigue calculation unit sets a weighting coefficient that increases as the amount of depression of the accelerator pedal increases, and calculates the cumulative value by multiplying the amount of depression by the weighting coefficient.

3. The driver assistance system according to claim 1, wherein the fatigue calculation unit calculates the rate of change of the amount the accelerator pedal is pressed, and further calculates the fatigue level using the rate of change.

4. The driver assistance system according to claim 3, wherein the fatigue calculation unit calculates the fatigue level such that when the rate of change represents the release operation of the accelerator pedal, the fatigue level is greater than when the rate of change represents the pressing operation of the accelerator pedal.

5. The system further includes a brake pedal operation state acquisition unit configured to acquire the operating state of the brake pedal operated by the aforementioned driver, The driving support system according to claim 1, wherein the fatigue level calculation unit further calculates the fatigue level using the brake pedal operation state acquired by the brake pedal operation state acquisition unit.

6. The driver assistance system according to claim 1, wherein the fatigue level calculation unit further calculates the fatigue level using the number of times the accelerator pedal is pressed.

7. The driver assistance system according to claim 1, wherein the fatigue calculation unit sets a correction element when the road on which the vehicle is traveling is congested, and calculates the fatigue level taking the correction element into account.

8. The driver assistance system according to claim 7, wherein the fatigue calculation unit sets the correction element based on at least one of the operating state of the brake pedal operated by the driver and the number of times the accelerator pedal is pressed.

9. The system further includes a driving support unit that performs driving support when the fatigue level calculated by the fatigue level calculation unit is equal to or greater than a predetermined threshold, The driving assistance system according to any one of claims 1 to 8, wherein the assistance for the driving operation includes at least one of notifying the driver and controlling the vehicle's speed.

Images