Driver condition determination device

Abstract

To provide a driver condition determining device that can sense deterioration of a physical function of a driver to promptly confirm a determination of an abnormal condition, early enough before the driver cannot drive a vehicle any more.SOLUTION: A driver condition determining device 10 comprises a vibrating device 14 that applies vibration to a steering wheel 2, a vibration detector 16 that detects vibrations 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 vibrating device. The controller makes the vibrating device apply vibrations of predetermined vibration frequencies f0 to the steering wheel, calculates steering torque levels in the vibration frequencies, on the basis of vibrations detected by the vibration detector, and determines that a driver is in an abnormal condition, when a coefficient of correlation between change with time of the steering torque levels during application of vibrations and change with time of the steering angle during the application of vibrations is equal to a predetermined value or more.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a driver condition determination device for determining whether a driver is in an abnormal state while driving a vehicle. [Background technology]

[0002] Conventionally, a device has been proposed that issues a warning to the driver by sound or light when it is determined that the driver is in an abnormal state (see, for example, Patent Document 1). In the device described in Patent Document 1, if a state in which the driver does not input any operation continues for a predetermined time (for example, 5 seconds) while the vehicle is traveling in an automatic driving assistance mode (for example, lane keeping assistance), a warning is issued to the driver. If there is a further period of time in which the driver does not input any operation, a warning and automatic intervention in vehicle operation (such as deceleration) is sequentially performed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6455456 Summary of the Invention [Problem to be solved by the invention]

[0004] When certain diseases (e.g., heart disease, brain disease, hypoglycemia, etc.) occur, the decline in bodily functions is thought to progress gradually from higher to lower functions. For example, the decline in voluntary movements (i.e., higher functions) progresses gradually over several tens of minutes until the driver is unable to drive. After that, the driver becomes unable to drive within a few seconds of the onset of the decline in involuntary movements (i.e., lower functions). During the decline in voluntary movements, for example, the driver's lane-keeping ability and speed maintenance ability are reduced compared to normal driving, but the driver can still operate the vehicle, albeit imperfectly. Therefore, conventional devices that determine an abnormal state when the driver becomes unable to operate the vehicle cannot determine an abnormal state during the decline in voluntary movements. On the other hand, once the decline in involuntary movements occurs, the driver becomes unable to operate the vehicle within a few seconds. Therefore, there may be little time between determining an abnormal state and confirming the driver's intentions or taking appropriate measures, such as automatically stopping the vehicle. Therefore, it is desirable to be able to accurately determine whether a driver is in an abnormal state before the decline in involuntary movements occurs, i.e., when the decline in voluntary movements occurs.

[0005] The present invention has been made to solve such problems, and aims to provide a driver condition determination device that can detect a decline in the driver's physical function at a stage well before the driver becomes unable to drive, and can quickly determine an abnormal state. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention provides a driver condition determination device for determining an abnormal state of a driver operating a vehicle, and includes a vibration device that applies vibration to the steering wheel of the vehicle's steering device, a vibration detector that detects 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 of a predetermined vibration frequency to the steering wheel using the vibration device, calculate a value representing the strength of the vibration detected at the vibration 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 in the value representing the strength of the vibration during the application of vibration and the time change in the steering angle during the application of vibration is greater than or equal to a predetermined value.

[0007] According to the present invention configured as described above, the controller determines that the driver is in an abnormal state when the correlation coefficient between the time change in the value representing the vibration intensity at the vibration frequency while vibration is being applied to the steering wheel and the time change in the steering angle while vibration is being applied is equal to or greater than a predetermined value. Therefore, the controller can determine the driver's abnormal state by utilizing the difference in muscle responsiveness depending on whether or not the driver has a disease when vibration is applied to the steering wheel, specifically, by utilizing the fact that the correlation between the time change in the steering angle and the time change in the value representing the detected vibration intensity at the vibration frequency changes depending on whether or not the driver has a disease. This makes it possible to detect a decline in the driver's physical function at a stage when voluntary motor function has declined, before the driver becomes unable to drive, and to determine the abnormal state at an early stage.

[0008] In the present invention, the vibration detector is preferably a steering torque sensor that detects the steering torque applied to the steering wheel, and the value representing the vibration intensity is an effective value at the excitation frequency of the steering torque detected by the steering torque sensor, or a decibel value obtained by leveling the effective value of the steering torque.

[0009] According to the present invention configured in this manner, the steering torque sensor can be used as a vibration detector without the need to install a new vibration detector, and the driver's abnormal state can be determined early based on the correlation between the time change in the effective value of the steering torque at the excitation frequency, or the time change in the decibel value obtained by leveling the effective value of the steering torque, and the time change in the steering angle.

[0010] In the present invention, preferably, a sensor for detecting the state of the driver is further provided, and when the controller estimates that the driver is in an abnormal state based on the detection signal of the sensor, the controller applies vibrations of the excitation frequency to the steering wheel using the vibration device. According to the present invention configured in this manner, when there is a relatively high possibility that the driver is in an abnormal state based on the detection signal of the sensor, it is possible to determine that the driver is in an abnormal state by applying vibrations, and it is possible to determine with high accuracy that the driver is in an abnormal state.

[0011] In the present invention, the vibration device is preferably an electric motor for an electric power steering device that assists the driver in steering the steering wheel. According to the present invention configured in this manner, the electric motor of the electric power steering device can be used as the vibration device without providing a new vibration device. [Effects of the Invention]

[0012] According to the driver condition determination device of the present invention, it is possible to detect a decline in the driver's physical function at a stage well before the driver becomes unable to drive, and to determine an abnormal state early. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an explanatory diagram of a vehicle equipped with a driver state determination device according to an embodiment of the present invention; [Figure 2] 1 is a block diagram of a driver state determination device according to an embodiment of the present invention. [Figure 3]10 is a graph showing the time change of the steering angle and the steering torque level at the excitation frequency according to an embodiment of the present invention. [Figure 4] 10 is a graph showing the change over time in steering angle and steering torque level at an excitation frequency according to an embodiment of the present invention. [Figure 5] 10 is a graph showing a correlation coefficient between a time change in steering angle and a time change in steering torque level at an excitation frequency according to an embodiment of the present invention. [Figure 6] 1 is a flowchart of an abnormal state determination process according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0014] A driver's condition determination device according to an embodiment of the present invention will be described below with reference to the accompanying drawings. Fig. 1 is an explanatory diagram of a vehicle equipped with the driver's condition determination device, and Fig. 2 is a block diagram of the driver's condition determination device.

[0015] 1, a driver state determination device 10 according to an embodiment 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) that connects the steering shaft 3 to steered wheels 4.

[0016] As shown in FIG. 2, the driver state determination device 10 includes one or more sensors 12 that detect the driver's state, a vibration device 14 that applies a predetermined vibration to the steering wheel 2, a vibration detector 16 that detects vibration of the steering wheel 2 or the steering shaft 3, a controller 18, and a vehicle driving control device 20.

[0017] The sensor 12 is a sensor that detects the driver's state. The driver's state includes the driver's physical state and the vehicle operation state by the driver. The sensor 12 that detects the physical state is, for example, an in-vehicle camera that captures an image of the driver, a heart rate sensor, an electrocardiogram sensor, a grip force sensor for the steering wheel 2, etc. The sensor 12 that detects the vehicle operation state is, for example, an outside-vehicle camera that captures an image outside the vehicle, a vehicle speed sensor, an acceleration sensor, a yaw rate sensor, a steering angle sensor, a steering torque sensor, an accelerator opening sensor, a brake pressure sensor, a GPS sensor, an ADAS sensor, etc.

[0018] For example, the controller 18 can use image signals (image data) of the driver captured by an in-vehicle camera to detect the driver's gaze direction, posture (upper body or head position), eyelid closure, and grip strength of the driver on the steering wheel 2, and can estimate 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 predetermined value, if the stability of the posture is below a predetermined value, if the eyelids are closed for a predetermined period of time, or if the grip strength of the steering wheel 2 is less than a predetermined value, the controller 18 can estimate that the driver is in an abnormal state based on a steering angle signal detected by a steering angle sensor, an image signal captured by an external camera, and the like. For example, if the stability of the position of the vehicle 1 from the center line on the road, the stability of the steering angle, and the like are below a predetermined value, the controller 18 can estimate that the driver is in an abnormal state.

[0019] The vibration device 14 is equipped with an electric motor capable of outputting reciprocating rotation, and is attached to the steering shaft 3. The vibration device 14 is configured to rotate the steering shaft 3 reciprocally in the circumferential direction at a predetermined frequency and at a small angle upon receiving a control signal. As a result, vibration of the predetermined frequency is applied to the steering wheel 2 via the steering shaft 3. In addition, a vibration detector 16 is attached to the steering shaft 3, and detects the vibration state of the steering wheel 2 via the steering shaft 3.

[0020] The vehicle 1 is equipped with an electric power steering device. The electric power steering device includes an electric motor connected to the steering shaft 3 to apply a steering assist torque, a steering torque sensor connected to the steering shaft 3 to detect the steering torque applied to the steering wheel 2, and the like. In this embodiment, among the components of the electric power steering device, the electric motor constitutes a vibration device 14, and the steering torque sensor constitutes a vibration detector 16.

[0021] Therefore, the electric motor operates as an electric power steering device to apply an assist torque to the steering shaft 3. In addition, the electric motor operates as a vibration device 14 to vibrate the steering shaft 3 and the steering wheel 2 by reciprocating the steering shaft 3 in the circumferential direction at a small angle.

[0022] The steering torque sensor also functions as an electric power steering device and vibration detector 16, and operates to detect the steering torque applied to the steering shaft 3 via the steering wheel 2. The steering torque sensor detects the vibration of the steering wheel 2 by detecting the fluctuation in the steering torque according to the circumferential torsion of the steering shaft 3. The controller 18 calculates the strength of the vibration of the steering wheel 2 at a predetermined frequency based on the change over time in the steering torque detected by the vibration detector 16 (steering torque sensor).

[0023] The controller 18 is a computer device equipped with a processor 18a as a CPU, a memory 18b (RAM, ROM, etc.) that stores various programs and databases, an input / output device for electric signals, etc. The controller 18 controls the sensor 12, the vibration device 14, the vibration detector 16, and the vehicle driving control device 20. When the controller 18 determines that the driver is in an abnormal state using the sensor 12, the vibration device 14, and the vibration detector 16, it is configured to send a control signal to the vehicle driving control device 20 and automatically drive the vehicle 1 to stop at a safe place. The vehicle driving control device 20 includes a steering control device, an engine control device, a drive electric motor control device, a brake control device, etc.

[0024] The controller 18 receives detection signals from the various sensors 12 and estimates whether the driver's physical functions have declined (whether the driver is in an abnormal state) based on the detection signals. If it is estimated that the driver is in an abnormal state, the controller 18 outputs an activation signal to the vibration device 14 for a predetermined period (e.g., one second) and receives a detection signal from the vibration detector 16. Based on the detection signal, the controller 18 determines whether the driver is in an abnormal state (confirms that the driver is in an abnormal state). Then, if it is determined that the driver is in an abnormal state, the controller 18 causes the vehicle 1 to stop automatically using the vehicle driving control device 20.

[0025] Next, the abnormal state determination process performed by the driver state determination device 10 of this embodiment will be described with reference to Figures 3 to 5. Figures 3 and 4 are graphs of the time change between the steering angle and the steering torque level at the excitation frequency, and Figure 5 is a graph of the correlation coefficient between the time change between the steering angle and the time change between the steering torque level at the excitation frequency.

[0026] Fig. 3 shows the time change of the steering angle and the time change of the steering torque level at the excitation frequency when the driver is in an abnormal state, while Fig. 4 shows the time change of the steering angle and the time change of the steering torque level at the excitation frequency when the driver is in a normal state.

[0027] The vibration device 14 applies vibration of a predetermined frequency (for example, excitation frequency f0 = 20 Hz) to the steering wheel 2 for a predetermined period of time. The vibration detector 16 outputs a detection signal detected for at least the predetermined period of time (for example, 1 second) to the controller 18. The controller 18 filters the detection signal, which is a time-series signal received from the vibration detector 16, using a Fourier transform or the like, to obtain a time-series signal of the steering torque at the excitation frequency f0. Furthermore, from the obtained time-series signal of the steering torque at the excitation frequency f0, it calculates a decibel value (steering torque level [dB]) that is a level of the effective value of the steering torque as a value representing the strength of vibration of the steering wheel 2 at the excitation frequency f0.

[0028] As can be seen from FIG. 3, in an abnormal state, when the change in the steering angle is large while vibration is being applied by the vibration device 14, the change in the steering torque level also becomes large.

[0029] On the other hand, as can be seen from FIG. 4, in the normal state, while vibration is being applied by the vibration device 14, the magnitude of the steering torque level is approximately constant regardless of the magnitude of the change in the steering angle.

[0030] Figure 5 shows the results of experiments using a vehicle simulator to determine the correlation coefficient between the time change in steering torque level and the time change in steering angle at the excitation frequency during vibration application for multiple subjects with disorders that affect driving ability level (simulating abnormal drivers) and multiple subjects without disorders (simulating normal drivers). As shown in Figure 5, for the abnormal drivers, the correlation coefficient averaged approximately 0.7, and even taking error into account, it was approximately 0.5 or more, indicating a strong correlation between the change in steering angle and the change in steering torque level. On the other hand, for the normal drivers, the correlation coefficient averaged approximately 0.3, and even taking error into account, it was less than 0.5, indicating no strong correlation between the change in steering angle and the change in steering torque level.

[0031] It has been known that disorders related to physical movement (e.g., disorders of the basal ganglia) can cause abnormalities in muscle tone and coordination. It is also known that muscle viscoelasticity changes depending on how muscle force is applied. Therefore, the inventors hypothesized that differences in the muscle movement and tone required to hold the steering wheel occur between a normal driver and a driver in an abnormal state with impaired physical function. This results in differences in muscle viscoelasticity, which in turn leads to differences in muscle response characteristics when vibrations are input to the driver's muscles via the steering wheel. Based on this hypothesis, the inventors conducted research and experimentally found that, as described above, the correlation between the time change in steering angle and the time change in steering torque level when vibrations are applied to the steering wheel changes depending on the presence or absence of a disease. In other words, the driver condition determination device of this embodiment utilizes these muscle response characteristics to apply vibrations to the steering wheel 2 and analyze the response to the vibrations to determine whether the driver is in an abnormal state.

[0032] Next, the flow of the abnormal state determination process performed by the driver state determination device 10 of this embodiment will be described with reference to Fig. 6. Fig. 6 is a flowchart of the abnormal state determination process.

[0033] 6 is started when the power supply of the vehicle 1 is turned on, and is repeatedly executed by the controller 18. When the abnormal state determination process is started, the controller 18 first acquires a detection signal from the sensor 12 (step S11), and estimates whether the driver is in a normal state or an abnormal state based on the detection signal (step S12). As a result, if it is estimated that the driver is not in an abnormal state (i.e., is in a normal state) (S12: No), the abnormal state determination process is terminated.

[0034] On the other hand, if it is estimated that the driver is in an abnormal state (step S12: Yes), the controller 18 outputs a control signal to cause the vibration device 14 to vibrate the steering wheel 2 at a predetermined vibration frequency f0 for a predetermined period (e.g., 1 second) (step S13). Furthermore, while the vibration device 14 is vibrating the steering wheel, 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).

[0035] When a predetermined period of time has elapsed (step S15: Yes), controller 18 filters the time-series signal of steering torque acquired from vibration detector 16 to acquire a time-series signal of steering torque at excitation frequency f0. Furthermore, from the acquired time-series signal of steering torque at excitation frequency f0, controller 18 calculates a steering torque level by leveling the effective value of the steering torque at excitation frequency f0. Then, controller 18 acquires a correlation coefficient between the time change of the steering torque level at excitation frequency f0 during application of vibration and the time change of the steering angle (step S16).

[0036] If the acquired correlation coefficient is less than a predetermined threshold (for example, 0.5) (step S17: No), the controller 18 determines that the driver is not in an abnormal state, and ends the abnormal state determination process.

[0037] On the other hand, if the correlation coefficient acquired in step S16 is equal to or greater than the predetermined threshold (step S17: Yes), the controller 18 determines that the driver is in an abnormal state (step S18) and executes an automatic driving intervention process (step S19). In the automatic driving intervention process, the controller 18 sends a control signal to the vehicle driving control device 20 to stop the vehicle 1 in a safe place by automatic driving, for example. After step S19, the controller 18 ends the abnormal state determination process.

[0038] In this embodiment, if an abnormal state of the driver is estimated in the process of step S12 (step S12: Yes), vibration is applied to the steering wheel 2 (step S13). However, apart from the process of step S12, vibration may be applied to the steering wheel 2 periodically to determine whether the driver is in an abnormal state (steps S16 and S17).

[0039] In addition, in this embodiment, a decibel value (steering torque level) obtained by leveling the effective value of the steering torque is used as a value representing the strength of vibration of the steering wheel 2 at the excitation frequency f0, but the effective value of the steering torque may be used instead, and the abnormal state of the driver may be determined based on the correlation coefficient between the time change in the effective value of the steering torque at the excitation frequency f0 and the time change in the steering angle.

[0040] Next, the operation and effect of the driver condition determination device 10 of the present embodiment will be described.

[0041] The controller 18 applies vibrations at a predetermined excitation frequency f0 to the steering wheel 2 using the vibration device 14, calculates a value representing the steering torque level at the excitation frequency f0 based on the vibrations detected by the vibration detector 16, and determines that the driver is in an abnormal state if the correlation coefficient between the time change in the steering torque level during application of the vibrations and the time change in the steering angle during application of the vibrations is equal to or greater than a predetermined value. This makes it possible to determine the driver's abnormal state by utilizing the difference in muscle responsiveness depending on whether or not the driver has a disease when vibrations are applied to the steering wheel 2, specifically, by utilizing the fact that the correlation between the time change in the steering angle and the time change in the value representing the strength of the detected vibrations at the excitation frequency f0 changes depending on whether or not the driver has a disease. Therefore, it is possible to detect a decline in the driver's physical function and determine the abnormal state early, at a stage when voluntary motor function declines, before the driver becomes unable to drive.

[0042] Furthermore, the vibration detector 16 is a steering torque sensor that detects the steering torque applied to the steering wheel 2, and the value that indicates the strength 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 obtained by leveling the effective value of the steering torque. This makes it possible to use the steering torque sensor as the vibration detector 16 without providing a new vibration detector 16, and makes it possible to quickly determine whether the driver is in an abnormal state based on the correlation between the time change in the effective value of the steering torque at the excitation frequency f0 or the time change in the decibel value obtained by leveling the effective value of the steering torque, and the time change in the steering angle.

[0043] Furthermore, when the controller 18 estimates that the driver is in an abnormal state based on the detection signal of the sensor 12, it causes the vibration device 14 to apply vibrations at a predetermined vibration frequency f0 to the steering wheel 2. As a result, when the detection signal of the sensor 12 indicates that there is a relatively high possibility that the driver is in an abnormal state, it is possible to determine whether the driver is in an abnormal state by applying vibrations, and it is possible to determine with high accuracy that the driver is in an abnormal state.

[0044] The vibration device 14 is an electric motor for an electric power steering device that assists the driver in steering the steering wheel 2. This allows the electric motor of the electric power steering device to be used as the vibration device 14, without the need to provide a new vibration device 14. [Explanation of symbols]

[0045] 1 vehicle 1a Steering gear 2 steering wheels 3 Steering shaft 10 Driver condition determination device 12 sensors 14 Vibration device (electric motor) 16 Vibration detector (steering torque sensor) 18 Controller 20 Vehicle driving control device

Claims

1. A driver condition determination device that determines an abnormal condition of a driver who drives a vehicle, a vibration device that applies vibration to a steering wheel of a steering device of the vehicle; a vibration detector that detects vibration of the steering wheel; a steering angle sensor for detecting a steering angle of the steering wheel; a controller for controlling the vibration device, The controller applying vibration of a predetermined vibration frequency to the steering wheel by the vibration device; calculating a value representing the intensity of the detected vibration at the excitation frequency based on the vibration detected by the vibration detector; the system is configured to determine that the driver is in an abnormal state when a correlation coefficient between a time change in a value representing the strength of the vibration while the vibration is being applied and a time change in the steering angle while the vibration is being applied is equal to or greater than a predetermined value. Driver condition determination device.

2. the vibration detector is a steering torque sensor that detects a steering torque applied to the steering wheel, 2. The driver state determination device according to claim 1, wherein the value representing the vibration intensity is an effective value of the steering torque detected by the steering torque sensor at the excitation frequency, or a decibel value obtained by leveling the effective value of the steering torque.

3. Further provided is a sensor for detecting the state of the driver, 3. The driver state determination device according to claim 1, wherein the controller applies vibrations of the excitation frequency to the steering wheel using the vibration device when it is estimated that the driver is in an abnormal state based on the detection signal of the sensor.

4. 3. The driver's state determination device according to claim 1, wherein the vibration device is an electric motor for an electric power steering device that assists the driver in steering the steering wheel.

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