Driver state determination device

Abstract

Provided is a driver state determination device capable of detecting a decrease in a driver's physical function at a stage sufficiently early before the driver becomes a state in which the driver cannot drive and determining an abnormal state at an early stage. The driver state determination device (10) includes a vibration device (14) that imparts a vibration to a steering wheel (2), a vibration detector (16) that detects the vibration of the steering wheel, a steering angle sensor (12) that detects a steering angle of the steering wheel, and a controller (18) that controls the vibration device. The controller imparts a vibration of a prescribed excitation frequency (f0) to the steering wheel by the vibration device, calculates a steering torque level at the excitation frequency based on the vibration detected by the vibration detector, and determines that the driver is in an abnormal state when a correlation coefficient of a time change in the steering torque level in the imparting of the vibration and a time change in the steering angle in the imparting of the vibration is a prescribed value or more.

Description

Technical Field

[0001] This invention relates to a driver state determination device for determining whether a driver is in an abnormal state while driving a vehicle. Background Technology

[0002] Previously, devices have been proposed that warn the driver via sound and lights if the driver is determined to be in an abnormal state (see, for example, Patent Document 1). In the device described in Patent Document 1, if the state of no driver input continues for a predetermined time (e.g., 5 seconds) while the vehicle is in an automated driving assistance mode (e.g., lane keeping assist), a warning is issued to the driver. Subsequently, if the time without driver input continues further, a warning is issued and automatic intervention in vehicle operation (such as deceleration) is performed in sequence.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 6455456 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] If a certain disease (such as heart disease, brain disease, hypoglycemia, etc.) occurs, it is believed that the decline in bodily functions gradually progresses from higher to lower functions. For example, the decline in voluntary motor function (i.e., higher functions) gradually develops to the point of inability to move within tens of minutes. Then, within a few seconds of the onset of involuntary motor function decline (i.e., lower functions), the driver is unable to perform driving operations. Here, in the decline of voluntary motor function, for example, although the driver's lane-keeping ability and speed-keeping ability are reduced compared to when healthy, although not completely, the driver can still operate the vehicle. Therefore, in conventional devices that determine an abnormal state when the driver is unable to operate, the abnormal state cannot be determined during the decline of voluntary motor function. On the other hand, if an involuntary motor function decline occurs, the driver is unable to operate within a few seconds, so the time leeway between determining the abnormal state and confirming the driver's intention or taking appropriate measures such as automatically stopping the vehicle may be small. Therefore, it is desirable to be able to determine with high accuracy that the driver is in an abnormal state before the onset of involuntary motor function decline, in other words, during the stage when voluntary motor function decline has occurred.

[0008] The present invention was made to solve such a problem, and aims to provide a driver state determination device that can detect the decline in the driver's physical function at a stage sufficiently earlier than the driver becomes incapacitated and determine the abnormal state at an early stage.

[0009] Methods for solving problems

[0010] To address the aforementioned issues, the present invention provides a driver state determination device for determining abnormal states of a driver of a vehicle. The device comprises: a vibration device that applies vibration to the steering wheel of the vehicle's steering mechanism; a vibration detector that detects the vibration of the steering wheel; a steering angle sensor that detects the steering angle of the steering wheel; and a controller that controls the vibration device. The controller is configured to apply vibration at a predetermined excitation frequency to the steering wheel via the vibration device, calculate a value representing the intensity of the detected vibration at the excitation frequency based on the vibration detected by the vibration detector, and determine that the driver is in an abnormal state if the correlation coefficient between the time change of the vibration intensity value during the vibration application period and the time change of the steering angle during the vibration application period is above a predetermined value.

[0011] According to the present invention configured as described above, when the correlation coefficient between the time change of the intensity value of vibration at the excitation frequency during the vibration applied to the steering wheel and the time change of the steering angle during the vibration application is above a predetermined value, the controller determines that the driver is in an abnormal state. Therefore, it can determine the driver's abnormal state by utilizing the difference in muscle responsiveness corresponding to the presence or absence of a disease when vibration is applied to the steering wheel; specifically, by utilizing the fact that the correlation between the time change of the steering angle and the time change of the detected intensity value of vibration at the excitation frequency changes depending on the presence or absence of a disease. Thus, it is possible to detect the decline in the driver's physical function and determine the abnormal state at an early stage, before the driver becomes unable to drive, during the phase of declining voluntary motor function.

[0012] In this invention, it is preferred that the vibration detector is a steering torque sensor that detects the steering torque applied to the steering wheel, and the value representing the intensity of the vibration is the effective value of the steering torque at the excitation frequency detected by the steering torque sensor, or a decibel value obtained by classifying the effective value of the steering torque.

[0013] According to the present invention configured in this way, there is no need to set up a new vibration detector. The steering torque sensor can be used as a vibration detector, and the abnormal state of the driver can be determined at an early stage based on the correlation between the time change of the effective value of the steering torque at the excitation frequency, or the time change of the decibel value after the effective value of the steering torque is graded, and the time change of the steering angle.

[0014] In this invention, it is preferable to further include a sensor for detecting the driver's state. When the controller infers that the driver is in an abnormal state based on the sensor's detection signal, it applies vibration at an excitation frequency to the steering wheel via a vibration device. According to this configuration, the invention can determine an abnormal state through vibration application based on the sensor's detection signal, even when the probability of the driver being in an abnormal state is relatively high, thus enabling highly accurate determination of whether the driver is in an abnormal state.

[0015] In this invention, the preferred vibration device is the electric motor of the electric power steering system, which assists the driver's steering wheel operation. According to this invention, there is no need to install a new vibration device; the electric motor of the electric power steering system can be used as the vibration device.

[0016] Invention Effects

[0017] According to the driver state determination device of the present invention, it is possible to detect the decline in the driver's physical function and determine the abnormal state at an early stage, before the driver becomes incapacitated. Attached Figure Description

[0018] Figure 1 This is an explanatory diagram of a vehicle equipped with a driver status determination device according to an embodiment of the present invention.

[0019] Figure 2 This is a block diagram of a driver status determination device according to an embodiment of the present invention.

[0020] Figure 3 This is a graph showing the time variation of steering angle and steering torque level under excitation frequency according to an embodiment of the present invention.

[0021] Figure 4 This is a graph showing the time variation of steering angle and steering torque level under excitation frequency according to an embodiment of the present invention.

[0022] Figure 5 This is a graph showing the correlation coefficient between the time variation of the steering angle and the time variation of the steering torque level at the excitation frequency in an embodiment of the present invention.

[0023] Figure 6 This is a flowchart of the abnormal state determination and processing according to an embodiment of the present invention.

[0024] Explanation of reference numerals in the attached figures

[0025] 1 vehicle

[0026] 1a Steering device

[0027] 2. Steering wheel

[0028] 3. Steering Axle

[0029] 10 Driver Status Determination Device

[0030] 12 sensors

[0031] 14. Vibration device (electric motor)

[0032] 16 Vibration detectors (steering torque sensors)

[0033] 18 controllers

[0034] 20 Vehicle driving control devices Detailed Implementation

[0035] Hereinafter, the driver status determination device according to an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 This is an explanatory diagram of a vehicle equipped with a driver status determination device. Figure 2 This is a block diagram of the driver status determination device.

[0036] like Figure 1 As shown, the driver state determination device 10 of the present invention is mounted on a vehicle 1 having a steering device 1a. The steering device 1a includes a steering wheel 2, a steering shaft 3 fixedly connected thereto, and a connecting mechanism (not shown) connecting the steering shaft 3 to the steering wheel 4.

[0037] like Figure 2 As shown, the driver state determination device 10 includes one or more sensors 12 for detecting the driver's state, a vibration device 14 for imparting a specified vibration to the steering wheel 2, a vibration detector 16 for detecting the vibration of the steering wheel 2 or the steering shaft 3, a controller 18, and a vehicle driving control device 20.

[0038] Sensor 12 is a sensor for detecting the driver's state. The driver's state includes the driver's physical state and the vehicle operation state performed by the driver. Sensors 12 for detecting physical state include, for example, an in-vehicle camera that captures images of the driver, a heart rate sensor, an electrocardiogram sensor, and a steering wheel 2 grip force sensor. In addition, sensors 12 for detecting vehicle operation state include, for example, an external camera that captures images of the outside of the vehicle, a vehicle speed sensor, an acceleration sensor, a yaw rate sensor, a steering angle sensor, a steering torque sensor, a throttle opening sensor, a brake pressure sensor, a GPS sensor, and ADAS sensors.

[0039] For example, the controller 18 can use the driver's image signal (image data) captured by the in-vehicle camera to detect the driver's gaze direction, posture (upper body or head position), eyelid opening, and steering wheel grip force, and infer that the driver is in an abnormal state based on these detection results. For example, if the stability of the gaze direction is below a specified value, if the stability of the posture is below a specified value, if the eyelids are closed for more than a specified time, or if the steering wheel grip force is less than a specified value, the controller 18 can infer that the driver is in an abnormal state. Furthermore, the controller 18 can also infer that the driver is in an abnormal state based on the steering angle signal detected by the steering angle sensor and the image signal captured by the external camera. For example, if the stability of the vehicle 1's position relative to the center line on the road and the stability of the steering angle are below specified values, the controller 18 can infer that the driver is in an abnormal state.

[0040] The vibration device 14 includes an electric motor capable of outputting reciprocating rotation and is mounted on the steering shaft 3. The vibration device 14 is configured such that, upon receiving a control signal, it causes the steering shaft 3 to reciprocate circumferentially at a predetermined frequency and a small angle. This imparts a predetermined frequency of vibration to the steering wheel 2 via the steering shaft 3. Furthermore, a vibration detector 16 is mounted on the steering shaft 3 to detect the vibration state of the steering wheel 2 via the steering shaft 3.

[0041] Vehicle 1 is equipped with an electric power steering system. The electric power steering system includes an electric motor connected to the steering shaft 3 to provide steering assistance torque, and a steering torque sensor connected to the steering shaft 3 to detect the steering torque applied to the steering wheel 2. In this embodiment, the electric motor in the electric power steering system constitutes a vibration device 14, and the steering torque sensor constitutes a vibration detector 16.

[0042] Therefore, the electric motor functions as an electric power steering device, providing auxiliary torque to the steering shaft 3. Additionally, the electric motor functions as a vibration device 14, causing the steering shaft 3 to reciprocate circumferentially at a small angle, thereby vibrating the steering shaft 3 and the steering wheel 2.

[0043] Additionally, the steering torque sensor, acting as both an electric power steering device and a vibration detector 16, detects the steering torque applied to the steering shaft 3 via the steering wheel 2. The steering torque sensor detects vibrations of the steering wheel 2 by detecting variations in the steering torque corresponding to the circumferential torsion of the steering shaft 3. The controller 18 calculates the intensity of the steering wheel 2's vibration at a predetermined frequency based on the time-varying steering torque detected by the vibration detector 16 (steering torque sensor).

[0044] The controller 18 is a computer device equipped with a processor 18a (CPU), a memory 18b (RAM, ROM, etc.) for storing various programs and databases, and input / output devices for electrical signals. The controller 18 controls the sensor 12, the vibration device 14, the vibration detector 16, and the vehicle driving control device 20. The controller 18 is configured such that if the sensor 12, the vibration device 14, and the vibration detector 16 determine that the driver is in an abnormal state, it sends a control signal to the vehicle driving control device 20, thereby enabling automatic driving to stop the vehicle 1 in a safe location. The vehicle driving control device 20 includes a steering control device, an engine control device, a drive motor control device, and a brake control device.

[0045] The controller 18 receives detection signals from various sensors 12 and infers whether the driver's physical function has declined (whether the driver is in an abnormal state) based on the detection signals. If the abnormal state is inferred, the controller 18 outputs a working signal for a specified period (e.g., 1 second) to the vibration device 14 and receives detection signals from the vibration detector 16. Based on the detection signals, the controller 18 determines whether the driver is in an abnormal state (determining if the driver is in an abnormal state). Furthermore, if the abnormal state is determined, the controller 18 uses the vehicle driving control device 20 to bring the vehicle 1 to a stop via automatic driving.

[0046] Next, refer to Figures 3-5 The abnormal state determination process of the driver state determination device 10 in this embodiment will be explained. Figure 3 as well as Figure 4 It is a graph showing the time-varying change of steering torque level at different steering angles and excitation frequencies. Figure 5 This is a graph showing the correlation coefficient between the time variation of the steering angle and the time variation of the steering torque level at the excitation frequency.

[0047] Figure 3 This shows the time variation of the steering angle and the time variation of the steering torque level at the excitation frequency when the driver is in an abnormal state. Additionally, Figure 4 This shows the time variation of the steering angle and the time variation of the steering torque level at the excitation frequency when the driver is in a normal state.

[0048] The vibration device 14 applies vibrations at a predetermined frequency to the steering wheel 2 for a predetermined period (e.g., excitation frequency f0 = 20 Hz). The vibration detector 16 outputs a detection signal detected for at least the aforementioned predetermined period (e.g., 1 second) to the controller 18. The controller 18 filters the timing signal received from the vibration detector 16, i.e., the detection signal, using Fourier transform or similar methods to obtain a timing signal of the steering torque at the excitation frequency f0. Furthermore, based on the obtained timing signal of the steering torque at the excitation frequency f0, a decibel value (steering torque level [dB]) after classifying the effective value of the steering torque is calculated, which is used as a value representing the intensity of the vibration of the steering wheel 2 at the excitation frequency f0.

[0049] according to Figure 3 It can be seen that under abnormal conditions, when the vibration is applied by the vibration device 14, the change in steering torque level also increases when the change in steering angle is large.

[0050] On the other hand, according to Figure 4 It can be seen that, under normal conditions, during the vibration imparted by the vibration device 14, the magnitude of the steering torque level is almost constant regardless of the magnitude of the change in steering angle.

[0051] Figure 5 The results show the correlation coefficients between the time variation of steering torque level and the time variation of steering angle at the excitation frequency of the vibration, obtained through experiments using a vehicle simulator. These results were presented for multiple subjects who were assumed to be in an abnormal state and suffered from a disease affecting their driving ability, and for multiple subjects who were assumed to be in a normal state and did not suffer from any disease. Figure 5 As shown, among drivers in abnormal conditions, the average correlation coefficient is approximately 0.7, and even considering the error, it is above 0.5, indicating a strong correlation between changes in steering angle and steering torque level. On the other hand, among drivers in normal conditions, the average correlation coefficient is approximately 0.3, and even considering the error, it is less than 0.5, indicating no strong correlation between changes in steering angle and steering torque level.

[0052] Previously, it was known that when a disease related to body movement occurs (e.g., a disease of the basal ganglia of the brain), muscle tension and coordination become abnormal. Furthermore, it is known that the viscoelasticity of muscles varies depending on the method of applying force to the muscles. Therefore, the inventors hypothesized that differences exist between the movement and tension of the muscles used to maintain the steering wheel in a driver in a normal state and a driver in an abnormal state with decreased bodily function. As a result, differences in muscle viscoelasticity occur, leading to differences in the muscle response characteristics when vibration is applied to the driver's muscles via the steering wheel. Based on this hypothesis, the inventors conducted further research, and as described above, experiments revealed that the correlation between the time-varying steering angle and the time-varying steering torque level when vibration is applied to the steering wheel varies depending on the presence or absence of a disease. That is, the driver state determination device of this embodiment utilizes these muscle response characteristics to determine whether the driver is in an abnormal state by applying vibration to the steering wheel 2 and analyzing its response.

[0053] Next, refer to Figure 6 The process for determining and processing abnormal states of the driver state determination device 10 in this embodiment will be explained. Figure 6 This is a flowchart for determining and handling abnormal states.

[0054] Figure 6 The abnormal state determination process begins when the power to vehicle 1 is turned on and is repeatedly executed by controller 18. After the abnormal state determination process begins, firstly, controller 18 obtains a detection signal from sensor 12 (step S11) and infers whether the driver is in a normal or abnormal state based on the detection signal (step S12). As a result, if it is inferred that the driver is not in an abnormal state (i.e., in a normal state) (S12: No), the abnormal state determination process ends.

[0055] On the other hand, if it is deduced that the driver is in an abnormal state (step S12: Yes), the controller 18 outputs a control signal and causes the steering wheel 2 to vibrate at a predetermined excitation frequency f0 for a predetermined period (e.g., 1 second) via the vibration device 14 (step S13). In addition, during the period when the steering wheel is vibrated by the vibration device 14, the controller 18 obtains the steering angle from the sensor 12 (steering angle sensor) and the steering torque from the vibration detector 16 (steering torque sensor) (step S14).

[0056] If the specified period has elapsed (step S15: Yes), the controller 18 filters the timing signal of the steering torque obtained from the vibration detector 16 to obtain the timing signal of the steering torque at the excitation frequency f0. Then, based on the obtained timing signal of the steering torque at the excitation frequency f0, the controller calculates the steering torque level after classifying the effective value of the steering torque at the excitation frequency f0. Finally, the correlation coefficient between the time variation of the steering torque level at the excitation frequency f0 and the time variation of the steering angle during vibration application is obtained (step S16).

[0057] Then, if the obtained correlation coefficient is less than a specified threshold (e.g., 0.5) (step S17: No), the controller 18 sets the driver to not be in an abnormal state and ends the abnormal state determination process.

[0058] On the other hand, if the correlation coefficient obtained in step S16 is above a predetermined threshold (step S17: Yes), the controller 18 determines that the driver is in an abnormal state (step S18) and executes autonomous driving intervention processing (step S19). In the autonomous driving intervention processing, the controller 18 sends a control signal to the vehicle driving control device 20, for example, to stop the vehicle 1 in a safe place through autonomous driving. After step S19, the controller 18 ends the abnormal state determination processing.

[0059] In addition, in this embodiment, during the processing of step S12, if it is deduced that the driver is in an abnormal state (step S12: Yes), vibration is applied to the steering wheel 2 (step S13). However, it is also possible to configure the steering wheel 2 to be vibrated periodically, separately from the processing of step S12, and to determine the abnormal state (steps S16, S17).

[0060] In addition, in this embodiment, the value representing the intensity of the vibration of the steering wheel 2 at the excitation frequency f0 is the decibel value (steering torque level) after the effective value of the steering torque is graded. However, the effective value of the steering torque can also be used, and the abnormal state of the driver can be determined based on the correlation coefficient between the time change of the effective value of the steering torque at the excitation frequency f0 and the time change of the steering angle.

[0061] Next, the effects of the driver status determination device 10 in this embodiment will be explained.

[0062] The controller 18 applies a prescribed excitation frequency f0 to the steering wheel 2 via the vibration device 14, and calculates a value representing the steering torque level at the excitation frequency f0 based on the vibration detected by the vibration detector 16. If the correlation coefficient between the time change of the steering torque level during vibration application and the time change of the steering angle during vibration application is above a predetermined value, the driver is determined to be in an abnormal state. Therefore, by utilizing the difference in muscle responsiveness corresponding to the presence or absence of a disease when vibration is applied to the steering wheel 2, specifically by utilizing the fact that the correlation between the time change of the steering angle and the time change of the detected vibration intensity value at the excitation frequency f0 changes according to the presence or absence of a disease, the driver's abnormal state can be determined. Thus, before the driver becomes unable to drive, during the stage of declining voluntary motor function, the decline in the driver's physical function can be detected, and the determination of an abnormal state can be made at an early stage.

[0063] Furthermore, the vibration detector 16 is a steering torque sensor that detects the steering torque applied to the steering wheel 2. The value representing the intensity of the vibration is the effective value of the steering torque at the excitation frequency f0 detected by the steering torque sensor, or a decibel value after classifying the effective value of the steering torque. Therefore, without the need to install a new vibration detector 16, the steering torque sensor can be used as the vibration detector 16, and the driver's abnormal state can be determined at an early stage based on the correlation between the time change of the effective value of the steering torque at the excitation frequency f0, or the time change of the decibel value after classifying the effective value of the steering torque, and the time change of the steering angle.

[0064] Furthermore, based on the detection signal from sensor 12, controller 18 applies a predetermined excitation frequency f0 to steering wheel 2 via vibration device 14 when it infers that the driver is in an abnormal state. Thus, based on the detection signal from sensor 12, when the probability of the driver being in an abnormal state is relatively high, it can determine the abnormal state based on the vibration applied, enabling high-precision determination of whether the driver is in an abnormal state.

[0065] Furthermore, the vibration device 14 is an electric motor used in the electric power steering system to assist the driver in steering the steering wheel 2. Therefore, there is no need to install a new vibration device 14; the electric motor of the electric power steering system can be used as the vibration device 14.

Claims

1. A driver state determination device for determining abnormal states of a driver operating a vehicle, characterized in that, have: A vibration device that imparts vibration to the steering wheel of the vehicle's steering system; A vibration detector detects the vibration of the steering wheel; A steering angle sensor detects the steering angle of the steering wheel; as well as The controller controls the vibration device. The controller is configured as follows: The steering wheel is subjected to vibration at a specified excitation frequency by the vibration device. Based on the vibration detected by the vibration detector, a value representing the intensity of the detected vibration at the excitation frequency is calculated. If the correlation coefficient between the time variation of the value representing the intensity of the vibration during the period of vibration application and the time variation of the steering angle during the period of vibration application is above a predetermined value, the driver is determined to be in an abnormal state.

2. The driver status determination device as described in claim 1, characterized in that, The vibration detector is a steering torque sensor that detects the steering torque applied to the steering wheel. The value representing the intensity of the vibration is the effective value of the steering torque detected by the steering torque sensor at the excitation frequency, or a decibel value obtained by classifying the effective value of the steering torque.

3. The driver status determination device as described in claim 1 or 2, characterized in that, It also has sensors to detect the driver's condition. When the controller infers that the driver is in an abnormal state based on the detection signal from the sensor, it applies vibration at the excitation frequency to the steering wheel through the vibration device.

4. The driver status determination device as described in claim 1 or 2, characterized in that, The vibration device is an electric motor used in an electric power steering system to assist the driver in steering the steering wheel.

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