Drowsiness estimation device and drowsiness estimation method

Abstract

This drowsiness estimation device is provided with: a sensing unit (11) that, on the basis of frames of captured images of the face of an occupant of a moving body, acquires drowsiness-related information for each frame; a first noise factor detection unit (12) that detects noise factor activity of the occupant on the basis of the drowsiness-related information; a feature quantity calculation unit (13) that calculates a drowsiness estimation feature quantity on the basis of noise factor-removed drowsiness-related information, which is obtained by removing, from the original drowsiness-related information, the drowsiness-related information on the basis of which the first noise factor detection unit (12) detected the noise factor activity; a drowsiness score calculation unit (14) that calculates a drowsiness score using the drowsiness estimation feature quantity calculated by the feature quantity calculation unit (13); and a drowsiness estimation unit (15) that estimates the occupant's drowsiness on the basis of the drowsiness score calculated by the drowsiness score calculation unit (14).

Description

Technical Field

[0001] The present disclosure relates to a drowsiness estimation device and a drowsiness estimation method.

Background Art

[0002] Generally, as characteristics of a person when drowsiness occurs, there are characteristics such as the opening of the eyes becoming small or the number of blinks increasing. Conventionally, as a technique for estimating the drowsiness of a passenger of a moving body based on this, there is a known technique for estimating the above-mentioned drowsiness using feature amounts such as the opening of the eyes or the number of blinks extracted using the information of the passenger's face (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In human behavior, there are behaviors similar to the characteristics when drowsiness occurs, such as so-called downward viewing, so-called frowning, or smiling. In the prior art, when estimating the drowsiness of a passenger, there is a problem that when the passenger exhibits behaviors similar to the characteristics when drowsiness occurs as described above, the estimation accuracy of the passenger's drowsiness may decrease. In addition, in the technique disclosed in Patent Document 1, when a change in the face orientation angle occurs immediately after the movement of the eyelids, or when the movement of the line of sight also occurs when the movement of the eyelids occurs, in order not to perform the determination of drowsiness, there is a possibility that the necessary determination of drowsiness itself is not performed, and the problem of still reducing the estimation accuracy of the passenger's drowsiness is not solved.

[0005] This disclosure is made to solve the above-mentioned problems and aims to provide a sleepiness estimation device that prevents a decrease in the accuracy of estimating sleepiness of an occupant of a mobile vehicle due to the occupant exhibiting behaviors similar to those that occur when sleepiness occurs. [Means for solving the problem]

[0006] The drowsiness estimation device according to this disclosure comprises: a sensing unit that acquires drowsiness-related information indicating the occupant's drowsiness-related state for each frame based on frames of captured images of the occupant's face of a moving vehicle; a first noise factor detection unit that detects noise factor behaviors, which are eye movements similar to drowsy-related behaviors performed by the occupant, based on the drowsiness-related information acquired by the sensing unit; a feature quantity calculation unit that calculates drowsiness estimation features for estimating the occupant's drowsiness based on drowsiness-related information after the noise factor removal unit has removed the drowsiness-related information that was the basis for the detection of noise factor behaviors by the first noise factor detection unit from the drowsiness-related information acquired by the sensing unit; a drowsiness score calculation unit that calculates a drowsiness score using the drowsiness estimation features calculated by the feature quantity calculation unit; and a drowsiness estimation unit that estimates the occupant's drowsiness based on the drowsiness score calculated by the drowsiness score calculation unit. The noise factor behavior includes downward gaze, and the first noise factor detection unit detects that the occupant was looking downward if, based on time-series drowsiness-related information, the occupant's gaze direction changes downward by an angle greater than or equal to the downward gaze determination angle during the downward gaze determination period. It is. [Effects of the Invention]

[0007] According to this disclosure, when estimating the drowsiness of an occupant of a mobile vehicle, it is possible to prevent a decrease in the accuracy of estimating the occupant's drowsiness due to the occupant exhibiting behaviors that have similar characteristics to those that occur when drowsiness occurs. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example configuration of the sleepiness estimation device according to Embodiment 1. [Figure 2] This is a flowchart illustrating the operation of the sleepiness estimation device according to Embodiment 1. [Figure 3]This flowchart illustrates the details of the feature calculation process in Embodiment 1, where the feature calculation unit identifies drowsiness-related information after noise factor removal based on exclusion flags assigned to drowsiness-related information to be excluded by the sensing result selection unit, and calculates drowsiness estimation features based on the identified drowsiness-related information after noise factor removal. [Figure 4] This flowchart illustrates the details of the feature calculation process in Embodiment 1, where the feature calculation unit calculates features for sleepiness estimation based on sleepiness-related information after noise factor removal output from the sensing result selection unit. [Figure 5] Figures 5A and 5B show an example of the hardware configuration of the sleepiness estimation device according to Embodiment 1. [Figure 6] This figure shows an example configuration of the sleepiness estimation device according to Embodiment 2. [Figure 7] This is a flowchart illustrating the operation of the drowsiness estimation device according to Embodiment 2. [Figure 8] This figure shows an example configuration of the sleepiness estimation device according to Embodiment 3. [Figure 9] This is a flowchart illustrating the operation of the drowsiness estimation device according to Embodiment 3. [Figure 10] This figure shows an example configuration of a sleepiness estimation device that combines the configurations of the sleepiness estimation device according to Embodiment 1, the sleepiness estimation device according to Embodiment 2, and the sleepiness estimation device according to Embodiment 3. [Figure 11] This is a flowchart illustrating the operation of a sleepiness estimation device that combines the configurations of the sleepiness estimation device according to Embodiment 1, the sleepiness estimation device according to Embodiment 2, and the sleepiness estimation device according to Embodiment 3. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described in detail below with reference to the drawings. Embodiment 1. FIG. 1 is a diagram showing a configuration example of a drowsiness estimation device 1 according to Embodiment 1. The drowsiness estimation device 1 according to Embodiment 1 is connected to an imaging device 2 and estimates the drowsiness of a person (hereinafter referred to as the "subject") who is the target of drowsiness estimation based on the image captured by the imaging device 2. In Embodiment 1, the subject is assumed to be a driver of a vehicle (not shown). Also, the drowsiness estimation device 1 according to Embodiment 1 is assumed to be mounted on the vehicle. In the following Embodiment 1, the driver of the vehicle is also simply referred to as the "driver".

[0010] The imaging device 2 is mounted on the vehicle. The imaging device 2 is installed at least at the center of the vehicle's dashboard, A-pillar, or meter panel so as to be able to image at least the driver's face. The imaging device 2 may be shared with a so-called "Driver Monitoring System (DMS)". The imaging device 2 is a visible light camera or an infrared camera. When the imaging device 2 is an infrared camera, the infrared camera is provided with a light source (not shown) that irradiates infrared light for imaging in the range including the driver's face. This light source is constituted by, for example, an LED (Light Emitting Diode). The imaging device 2 outputs the captured image (hereinafter referred to as the "captured image") to the drowsiness estimation device 1.

[0011] The drowsiness estimation device 1 includes a sensing unit 11, a first noise factor detection unit 12, a feature quantity calculation unit 13, a drowsiness score calculation unit 14, and a drowsiness estimation unit 15. The feature quantity calculation unit 13 includes a sensing result selection unit 131.

[0012] The sensing unit 11 acquires information indicating a state related to the drowsiness of the driver (hereinafter referred to as "drowsiness-related information") based on the captured image of the driver's face. Note that the sensing unit 11 acquires the captured image from the imaging device 2 in frame units. The sensing unit 11 acquires the drowsiness-related information for each frame. In Embodiment 1, the process of acquiring drowsiness-related information performed by the sensing unit 11 is referred to as the "sensing process".

[0013] The state related to the driver's drowsiness includes how much the driver's eyes are open (in other words, the eyelid opening degree), how much the driver's mouth is open (in other words, the mouth opening degree), the positions of the feature points on the driver's face, the driver's line of sight direction, the driver's face orientation, the driver's head position, etc. The feature points on the face are the outer corners of the eyes, the inner corners of the eyes, points on the outer periphery of the eyes, etc. The positions of the feature points on the driver's face are indicated by, for example, coordinates on the captured image. The driver's face orientation is represented by an angle, for example, with the case where the driver is facing forward with respect to the traveling direction of the vehicle as the reference (0 degrees). The driver's head position is represented by coordinates in the real space. Since the installation position and the angle of view of the imaging device 2 are known in advance, the sensing unit 11 can calculate the driver's face orientation and head position from the captured image. In Embodiment 1, what kind of state is regarded as a state related to the driver's drowsiness is determined in advance by an administrator or the like.

[0014] The sensing unit 11 may detect a state related to the driver's drowsiness using a known image recognition technique and acquire drowsiness-related information. The sensing unit 11 outputs the acquired drowsiness-related information to the first noise factor detection unit 12. At this time, the sensing unit 11 may, for example, associate the frame of the captured image from which the drowsiness-related information was acquired with the drowsiness-related information and output it to the first noise factor detection unit 12. In the following description, the drowsiness-related information output by the sensing unit 11 to the first noise factor detection unit 12, or the information in which the drowsiness-related information is associated with the frame of the captured image that is the source of the drowsiness-related information, is also referred to as the "sensing result". It is assumed that information indicating the capture date and time is attached to each frame of the captured image.

[0015] [[ID=*16]] The first noise factor detection unit 12 detects driver actions that involve eye movements and are similar to actions caused by drowsiness, based on drowsiness-related information acquired by the sensing unit 11 (hereinafter referred to as "noise factor actions"). In Embodiment 1, the process performed by the first noise factor detection unit 12 to detect noise factors is referred to as the "first noise factor detection process."

[0016] Examples of noise-causing behaviors include looking downwards (so-called downward gaze) or squinting. For example, when a driver looks at the instrument panel, they may be looking downwards. Furthermore, for example, a driver may make a so-called "grimacing face" when the sunlight is too bright. In Embodiment 1, this so-called grimacing face is also called a "patient face." Generally, when a person makes a "patient face," they narrow their eyes. Also, for example, generally, when a person smiles, they narrow their eyes.

[0017] On the other hand, when a person feels sleepy, they either cover their eyes with their eyelids to close them, or close their eyes to try and get rid of the sleepiness. When the eyes are covered with the eyelids or when the eyes are closed, the eyes become narrower.

[0018] Thus, the aforementioned behaviors such as looking downwards, making a pained expression, or smiling can be considered noise-generating behaviors similar to those caused by drowsiness, such as covering one's eyes with the eyelids or closing one's eyes. The first noise source detection unit 12 detects such noise source behavior. Furthermore, the types of behaviors that constitute noise-generating behaviors are predetermined by the administrators or other relevant personnel.

[0019] For example, if the noise-causing behavior is squinting, the first noise-causing behavior detection unit 12 detects that the driver has engaged in noise-causing behavior if, based on drowsiness-related information, the driver's eyelid opening degree is below a preset threshold (hereinafter referred to as the "eyelid opening degree determination threshold"). The first noise factor detection unit 12 may, for example, detect a noise factor behavior by the driver when the degree of eyelid opening of the driver becomes smaller than or equal to a preset threshold (hereinafter referred to as the "eyelid opening difference determination threshold") compared to the degree of eyelid opening based on the immediately preceding drowsiness-related information, based on time-series drowsiness-related information. The first noise factor detection unit 12 stores the sensing results acquired from the sensing unit 11 in a memory unit that is not shown in the time series. Based on the sensing results stored in the memory unit, the first noise factor detection unit 12 can identify the immediately preceding drowsiness-related information. The memory unit is located in a place accessible to the drowsiness estimation device 1. The threshold values ​​for determining the degree of eyelid opening and the threshold values ​​for determining the difference in the degree of eyelid opening are set as appropriate by the administrator or other relevant personnel and stored in the memory unit. In this case, drowsiness-related information includes at least the driver's eyelid opening degree.

[0020] Furthermore, for example, the first noise factor detection unit 12 may use a model that has previously learned the "endurance face" (hereinafter referred to as the "machine learning model") to detect when a noise factor behavior has occurred by the driver. The machine learning model used by the first noise factor detection unit 12 to detect noise factor behavior by the driver is also called the "first machine learning model." The first machine learning model is a machine learning model such as SVM (Support Vector Machine), Random Forest, LightGBM (Light Gradient Boosting Machine), or Convolutional Neural Network. The first machine learning model takes information indicating the location of feature points on a person's face in an image as input and outputs information indicating whether or not the person is making a face of endurance. The first machine learning model is pre-generated and stored in the memory unit. The first noise factor detection unit 12 inputs drowsiness-related information into the first machine learning model to obtain information indicating whether or not the driver is making a face indicating they are trying to endure the drowsiness, thereby detecting whether or not the driver is making a face indicating they are trying to endure the drowsiness. In this case, the drowsiness-related information includes at least the positional information of the driver's facial feature points on the captured image.

[0021] Furthermore, for example, if the noise-causing behavior is looking downwards, the first noise-causing behavior detection unit 12 detects, based on drowsiness-related information, that the driver has engaged in noise-causing behavior if the driver's gaze direction is below a preset threshold (hereinafter referred to as the "gaze direction determination threshold"). The first noise factor detection unit 12 may, for example, detect that a noise factor has occurred by the driver if the driver's gaze direction changes downward by a predetermined angle (hereinafter referred to as the "downward gaze determination angle") or more within a predetermined period (hereinafter referred to as the "downward gaze determination period") based on time-series drowsiness-related information. The threshold for determining the direction of gaze, the period for determining downward gaze, and the angle for determining downward gaze are set appropriately by the administrator or other relevant personnel according to the installation position and field of view of the imaging device 2, and are stored in the memory unit. In this case, drowsiness-related information includes at least the driver's gaze direction.

[0022] When the first noise factor detection unit 12 detects that a noise factor has occurred by the driver, it outputs information regarding the detected noise factor (hereinafter referred to as "noise factor information") to the feature calculation unit 13, along with the sensing results obtained from the sensing unit 11. The noise-causing behavior information includes information indicating that the first noise-causing behavior was detected by the first noise-causing behavior detection unit 12, and drowsiness-related information that led the first noise-causing behavior detection unit 12 to detect the noise-causing behavior. The noise-causing behavior information may further include information that can identify the type of noise-causing behavior detected by the first noise-causing behavior detection unit 12 (e.g., looking downwards, squinting).

[0023] The feature calculation unit 13 calculates features for estimating driver drowsiness (hereinafter referred to as "drowsiness estimation features") based on the drowsiness-related information obtained by the sensing unit 11, after the drowsiness-related information that the first noise factor detection unit 12 used to detect noise factor behavior has been removed (hereinafter referred to as "drowsiness-related information after noise factor removal"). In Embodiment 1, the process performed by the feature calculation unit 13 to calculate features for drowsiness estimation is referred to as the "feature calculation process."

[0024] The calculation of features for drowsiness estimation by the feature calculation unit 13 will be explained in detail.

[0025] First, the sensing result selection unit 131, which is part of the feature calculation unit 13, assigns an exclusion flag to the sleepiness-related information acquired by the sensing unit 11 that is to be excluded when calculating sleepiness estimation features, based on the noise factor behavior information related to noise factor behavior detected by the first noise factor detection unit 12.

[0026] For example, suppose the first noise factor detection unit 12 detects a noise factor behavior, which is the act of squinting. In this case, the sensing result selection unit 131 excludes the drowsiness-related information included in the sensing result that was the source of the noise factor behavior detected by the first noise factor detection unit 12. The sensing result selection unit 131 then assigns an exclusion flag to the drowsiness-related information to be excluded in the sensing result. As described above, the first noise factor detection unit 12 outputs the sensing results obtained from the sensing unit 11, along with the noise factor behavior information, to the feature calculation unit 13. Therefore, the sensing result selection unit 131 can identify the drowsiness-related information to be excluded from the noise factor behavior information and sensing results output from the first noise factor detection unit 12. The sensing result selection unit 131, based on the sensing results output from the first noise factor detection unit 12, assigns an exclusion flag to any drowsiness-related information included in the sensing results if it is drowsiness-related information that should be excluded. The sensing result selection unit 131 then outputs the sensing results, after assigning the exclusion flag to the drowsiness-related information to be excluded, to the feature calculation unit 13.

[0027] Next, the feature calculation unit 13 identifies the sleepiness-related information after the first noise factor detection unit 12 has detected noise factor behaviors, i.e., the sleepiness-related information after noise factor removal, by excluding the sleepiness-related information that the first noise factor detection unit 12 has identified as the source of the sleepiness-related information acquired by the sensing unit 11, based on the sensing results output from the sensing result selection unit 131. Then, the feature calculation unit 13 calculates features for sleepiness estimation based on the sleepiness-related information after removing the identified noise factors. In other words, the feature calculation unit 13 calculates features for sleepiness estimation based on sleepiness-related information that has not been flagged for exclusion, which is obtained from the sensing unit 11 via the first noise factor detection unit 12. Features used for estimating drowsiness include, for example, eyelid opening degree, mouth opening degree, driver's face orientation, driver's head position, driver's gaze direction, driver's PERCLOS (Percent of the time eyelids are closed), driver's blink count, or driver's blinking speed. The feature calculation unit 13 calculates the drowsiness estimation features described above based on the drowsiness-related information after noise factor removal.

[0028] Furthermore, if the features used for estimating drowsiness are features that need to be determined from the history of the driver's state, such as PERCLOS, blink count, or blink speed, the feature calculation unit 13 stores, for example, the sensing results output from the sensing result selection unit 131, and calculates the features used for estimating drowsiness based on the stored sensing results and the past several minutes of pre-set drowsiness-related information. The feature calculation unit 13 may, for example, calculate sleepiness estimation features based on sleepiness-related information after noise factor removal acquired during a previously stored, pre-set period (hereinafter referred to as the "feature calculation target period").

[0029] For example, if the feature calculation period is 3 minutes, the feature calculation unit 13 calculates sleepiness estimation features based on sleepiness-related information obtained after noise factor removal from the past 3 minutes, looking back from the present. In the drowsiness-related information after noise factor removal, drowsiness-related information acquired based on captured images obtained from the imaging device 2 is excluded. More specifically, among the drowsiness-related information acquired by the sensing unit 11 based on the imaging device 2, drowsiness-related information that was the basis for the first noise factor detection unit 12 detecting noise factor behavior is excluded. In other words, the feature calculation unit 13 does not use drowsiness-related information acquired based on frames of captured images in which a driver exhibiting noise factor behavior is captured in the calculation of drowsiness estimation features. More specifically, the feature calculation unit 13 does not use drowsiness-related information acquired based on frames of captured images in which a driver exhibiting noise factor behavior is captured in the calculation of drowsiness estimation features.

[0030] The feature calculation unit 13 outputs information (hereinafter referred to as "feature information") that associates drowsiness-related information, more specifically, drowsiness-related information after noise factor removal, with the calculated drowsiness estimation features to the drowsiness score calculation unit 14.

[0031] In this case, as described above, the sensing result selection unit 131 assigns an exclusion flag to the drowsiness-related information acquired by the sensing unit 11, and the feature calculation unit 13 identifies the drowsiness-related information after noise factor removal based on the exclusion flag, and calculates drowsiness estimation features from the identified drowsiness-related information after noise factor removal. However, this is just one example, and the feature calculation unit 13 may calculate the features for drowsiness estimation using other methods. For example, the sensing result selection unit 131 identifies drowsiness-related information to be excluded based on noise factor behavior information related to noise factor behavior detected by the first noise factor detection unit 12. Then, it excludes the identified drowsiness-related information to be excluded from the drowsiness-related information acquired by the sensing unit 11 that is included in the sensing results, and selects the drowsiness-related information after exclusion as drowsiness-related information after noise factor removal. When the sensing result selection unit 131 selects drowsiness-related information after noise factor removal, it outputs the sensing result including the selected drowsiness-related information after noise factor removal (hereinafter referred to as "noise-removed sensing result") to the feature calculation unit 13. The feature calculation unit 13 calculates features for sleepiness estimation based on the sleepiness-related information after noise factor removal output from the sensing result selection unit 131. In other words, the feature calculation unit 13 calculates sleepiness estimation features based on sleepiness-related information selected by the sensing result selection unit 131, which is included in the noise-removed sensing results from the sleepiness-related information acquired from the sensing unit 11 via the first noise factor detection unit 12. The feature calculation unit 13 may calculate the features for estimating drowsiness in this manner.

[0032] The drowsiness score calculation unit 14 calculates a drowsiness score using the drowsiness estimation features calculated by the feature calculation unit 13. The drowsiness score calculation unit 14 can identify the drowsiness estimation features calculated by the feature calculation unit 13 from the feature information output from the feature calculation unit 13. The drowsiness score calculated by the drowsiness score calculation unit 14 is a score that indicates the degree of driver drowsiness and is used to estimate the driver's drowsiness. In Embodiment 1, as an example, the drowsiness score is represented as "0" to "100", and a higher drowsiness score indicates a higher degree of driver drowsiness. The driver's drowsiness is estimated using the drowsiness score by the drowsiness estimation unit 15. In Embodiment 1, the process performed by the drowsiness score calculation unit 14 to calculate the drowsiness score is referred to as the "drowsiness score calculation process."

[0033] The drowsiness score calculation unit 14 calculates the drowsiness score, for example, using a machine learning model that has been pre-trained on drowsiness scores. The machine learning model used by the drowsiness score calculation unit 14 to calculate the drowsiness score is also called the "second machine learning model." The second machine learning model is a machine learning model such as SVM (Support Vector Machine), Random Forest, LightGBM (Light Gradient Boosting Machine), or Convolutional Neural Network. The second machine learning model takes, for example, features for drowsiness estimation as input and outputs a drowsiness score. The second machine learning model is pre-generated and stored in a location accessible to the drowsiness score calculation unit 14, such as the memory unit. The drowsiness score calculation unit 14 calculates the drowsiness score by inputting drowsiness estimation features into the second machine learning model to obtain the drowsiness score.

[0034] The drowsiness score calculation unit 14 may, for example, calculate the drowsiness score based on a pre-set rule for calculating the drowsiness score (hereinafter referred to as the "drowsiness score calculation rule"). The rules for calculating the drowsiness score are generated in advance by an administrator or similar person and stored in a location accessible to the drowsiness score calculation unit 14, such as a memory unit. The rules for calculating the drowsiness score include, for example, "If the number of blinks in the past 3 minutes is 20 or more, the drowsiness score will be '60'," which are rules for calculating the drowsiness score based on the number of blinks over a set period.

[0035] The drowsiness score calculation unit 14 outputs the calculated driver's drowsiness score to the drowsiness estimation unit 15.

[0036] The drowsiness estimation unit 15 estimates the driver's drowsiness based on the drowsiness score calculated by the drowsiness score calculation unit 14. The driver's drowsiness estimated by the drowsiness estimation unit 15 may be represented by multiple states, such as "awake," "mildly drowsy," and "severely drowsy," or it may be represented by a binary value, such as "drowsy" or "not drowsy," or it may be a continuous value indicating the degree of drowsiness. In Embodiment 1, the process performed by the drowsiness estimation unit 15 to estimate the driver's drowsiness is referred to as the "drowsiness estimation process."

[0037] The drowsiness estimation unit 15 estimates the driver's drowsiness, for example, using a machine learning model that has been pre-trained on drowsiness. The machine learning model used by the drowsiness estimation unit 15 to estimate driver drowsiness is also called the "third machine learning model." The third machine learning model is a machine learning model such as SVM (Support Vector Machine), Random Forest, LightGBM (Light Gradient Boosting Machine), or Convolutional Neural Network. The third machine learning model, for example, takes a drowsiness score as input and outputs information indicating drowsiness. This information may include, for example, information indicating multiple states of driver drowsiness, information indicating whether the driver is "drowsy" or "not drowsy," or a continuous value indicating the degree of drowsiness. The third machine learning model is pre-generated and stored in a location accessible to the sleepiness estimation unit 15, such as the memory unit. The drowsiness estimation unit 15 estimates the driver's drowsiness by inputting a drowsiness score into a third machine learning model to obtain information indicating drowsiness.

[0038] The drowsiness estimation unit 15 may, for example, estimate the driver's drowsiness based on pre-set rules for estimating the driver's drowsiness (hereinafter referred to as "drowsiness estimation rules"). The rules for estimating drowsiness are generated in advance by an administrator or similar person and stored in a location accessible to the drowsiness estimation unit 15, such as a memory unit. The rules for estimating drowsiness include conditions that associate the range of the drowsiness score with information indicating multiple states of driver drowsiness, such as "If the drowsiness score is between '0' and '50', the driver is 'awake'; if the drowsiness score is between '50' and '60', the driver is 'mildly drowsy'; and if the drowsiness score is '60' or higher, the driver is 'severely drowsy'"; conditions such as "If the drowsiness score is '60' or higher, the driver is 'drowsy'; if the drowsiness score is less than '60', the driver is 'not drowsy'"; or a formula for calculating the degree of drowsiness based on the drowsiness score.

[0039] The drowsiness estimation unit 15 outputs the driver's drowsiness estimation result (hereinafter referred to as "drowsiness estimation result") to an external device (not shown) of the drowsiness estimation device 1. For example, the drowsiness estimation unit 15 outputs the drowsiness estimation result to a warning device installed in the vehicle. If the drowsiness estimation result indicates that the driver is drowsy, the warning device outputs a warning. For example, the sleepiness estimation unit 15 may store the sleepiness estimation result in the memory unit.

[0040] The operation of the drowsiness estimation device 1 according to Embodiment 1 will be described below. Figure 2 is a flowchart illustrating the operation of the drowsiness estimation device 1 according to Embodiment 1. For example, when the vehicle's power is turned on and an image is output from the imaging device 2, the drowsiness estimation device 1 repeats the operations shown in the flowchart of Figure 2 until the vehicle's power is turned off.

[0041] The sensing unit 11 acquires an image of the driver's face from the imaging device 2 and performs sensing processing to acquire drowsiness-related information based on the acquired image (step ST10). The sensing unit 11 outputs the sensing result to the first noise source detection unit 12.

[0042] The first noise factor detection unit 12 performs a first noise factor detection process (step ST20) to detect noise factor behaviors by the driver that are similar to behaviors caused by drowsiness, based on the drowsiness-related information acquired by the sensing unit 11 in step ST10. When the first noise source detection unit 12 detects that a noise source behavior has occurred by the driver, it outputs the noise source behavior information, along with the sensing results obtained from the sensing unit 11, to the feature calculation unit 13. Furthermore, if the first noise factor detection unit 12 does not detect any noise-causing behavior by the driver, it may output information to the feature calculation unit 13 indicating that it did not detect any noise-causing behavior, or it may choose not to output anything to the feature calculation unit 13.

[0043] The feature calculation unit 13 performs a feature calculation process to calculate drowsiness estimation features based on the drowsiness-related information after noise factor removal, which is obtained by excluding the drowsiness-related information that the first noise factor detection unit 12 used to detect noise factor behaviors in step ST20, from the drowsiness-related information acquired by the sensing unit 11 in step ST10 (step ST30). More specifically, the feature calculation unit 13 performs a feature calculation process to calculate drowsiness estimation features based on the drowsiness-related information after noise factor removal, which is obtained by excluding the drowsiness-related information that the first noise factor detection unit 12 used to detect noise factor behaviors, from the drowsiness-related information acquired by the sensing unit 11. The feature extraction unit 13 outputs the feature information to the drowsiness score calculation unit 14.

[0044] The drowsiness score calculation unit 14 performs a drowsiness score calculation process (step ST40) using the drowsiness estimation features calculated by the feature calculation unit 13 in step ST30 to calculate the drowsiness score. The drowsiness score calculation unit 14 outputs the calculated driver's drowsiness score to the drowsiness estimation unit 15.

[0045] The drowsiness estimation unit 15 performs a drowsiness estimation process to estimate the driver's drowsiness based on the drowsiness score calculated by the drowsiness score calculation unit 14 in step ST40 (step ST50). The drowsiness estimation unit 15 outputs the driver drowsiness estimation result.

[0046] Figure 3 is a flowchart illustrating an example of the details of the process in step ST30 of Figure 2. More specifically, Figure 3 is a flowchart illustrating the details of the feature calculation process in Embodiment 1, where the feature calculation unit 13 identifies drowsiness-related information after noise factor removal based on exclusion flags assigned to drowsiness-related information to be excluded by the sensing result selection unit 131, and calculates drowsiness estimation features based on the identified drowsiness-related information after noise factor removal.

[0047] Based on the noise factor behavior information related to the noise factor behavior detected by the first noise factor detection unit 12, the sensing result selection unit 131 assigns an exclusion flag to the drowsiness-related information acquired by the sensing unit 11 that is to be excluded when calculating the drowsiness estimation feature (step ST301). The sensing result selection unit 131 outputs the sensing results to the feature calculation unit 13 after adding an exclusion flag to the drowsiness-related information to be excluded.

[0048] Based on the sensing results output from the sensing result selection unit 131 in step ST301, the feature calculation unit 13 identifies the drowsiness-related information after noise factor removal by excluding the drowsiness-related information to be excluded, which has been flagged for exclusion by the sensing result selection unit 131, from the drowsiness-related information acquired by the sensing unit 11 (step ST302).

[0049] Then, the feature calculation unit 13 calculates features for sleepiness estimation based on the sleepiness-related information after noise factor removal identified in step ST302 (step ST303). The feature extraction unit 13 outputs the feature information to the drowsiness score calculation unit 14.

[0050] Figure 4 is a flowchart illustrating another example of the details of the process in step ST30 of Figure 2. More specifically, Figure 4 is a flowchart illustrating the details of the feature calculation process in Embodiment 1, where the feature calculation unit 13 calculates features for sleepiness estimation based on sleepiness-related information after noise factor removal output from the sensing result selection unit 131.

[0051] The sensing result selection unit 131 identifies drowsiness-related information to be excluded based on noise factor behavior information related to noise factor behavior detected by the first noise factor detection unit 12. Then, it excludes the identified drowsiness-related information to be excluded from the drowsiness-related information acquired by the sensing unit 11 that is included in the sensing results, and selects the drowsiness-related information after exclusion as drowsiness-related information after noise factor removal (step ST311). When the sensing result selection unit 131 selects drowsiness-related information after noise factor removal, it outputs the noise-removed sensing result to the feature calculation unit 13.

[0052] The feature calculation unit 13 calculates features for sleepiness estimation based on the sleepiness-related information after noise factor removal output from the sensing result selection unit 131 in step ST311 (step ST312). The feature extraction unit 13 outputs the feature information to the drowsiness score calculation unit 14.

[0053] In this way, the drowsiness estimation device 1 acquires drowsiness-related information frame by frame based on the captured image of the driver's face, and detects noise factor behaviors by the driver that are similar to behaviors caused by drowsiness based on the acquired drowsiness-related information. The drowsiness estimation device 1 calculates drowsiness estimation features based on the drowsiness-related information after removing the drowsiness-related information that was the source of the detection of noise factor behaviors from the acquired drowsiness-related information. Then, the drowsiness estimation device 1 calculates a drowsiness score using the drowsiness estimation features, and estimates the driver's drowsiness based on the calculated drowsiness score.

[0054] Human behavior includes actions that exhibit characteristics similar to those associated with drowsiness, such as looking downwards, frowning, or smiling; in other words, these are considered "noise factor" behaviors. In conventional technology, when estimating driver drowsiness, the accuracy of the estimate may decrease if the driver engages in the noise-generating behaviors described above. More specifically, in conventional technology, when estimating driver drowsiness, the features calculated based on the facial information of a driver engaging in noise-generating behavior—that is, the captured image of the driver's face—may become noise, potentially reducing the accuracy of the driver drowsiness estimate.

[0055] In response to this, the drowsiness estimation device 1 calculates drowsiness estimation features based on drowsiness-related information after noise factor removal, as described above, and estimates the driver's drowsiness based on the drowsiness score calculated using the drowsiness estimation features. Therefore, the drowsiness estimation device 1 can prevent a decrease in the accuracy of estimating a driver's drowsiness due to the driver engaging in noise-generating behavior. More specifically, the drowsiness estimation device 1 can prevent a decrease in the accuracy of estimating a driver's drowsiness due to the use of noise-generating features in the driver's drowsiness estimation, thereby enabling highly accurate drowsiness estimation. Furthermore, when estimating driver drowsiness, the noisy features are those calculated based on captured images of drivers exhibiting noise-causing behaviors. Features calculated based on captured images of drivers not exhibiting noise-causing behaviors are necessary for accurate driver drowsiness estimation. The drowsiness estimation device 1 removes only the noise features calculated due to noise-causing behaviors such as looking downwards, even if the driver is engaging in such behaviors. The remaining features, after the noise features have been removed, are used as drowsiness estimation features to estimate the driver's drowsiness. In other words, even if the driver is engaging in noise-causing behaviors, the drowsiness estimation device 1 does not stop estimating the driver's drowsiness altogether, but instead uses the necessary features to perform the drowsiness estimation. This prevents the drowsiness estimation device 1 from reducing the accuracy of the driver's drowsiness estimation by preventing the use of noise features, thereby enabling highly accurate drowsiness estimation.

[0056] Figures 5A and 5B show an example of the hardware configuration of the sleepiness estimation device 1 according to Embodiment 1. In Embodiment 1, the functions of the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, and the drowsiness estimation unit 15 are realized by the processing circuit 1001. That is, the drowsiness estimation device 1 includes a processing circuit 1001 for controlling the estimation of the driver's drowsiness based on the captured image acquired from the imaging device 2, using the feature quantities obtained by excluding the feature quantities calculated due to the driver engaging in noise factor behavior as drowsiness estimation feature quantities. The processing circuit 1001 may be dedicated hardware as shown in Figure 5A, or it may be a processor 1004 that executes a program stored in memory as shown in Figure 5B.

[0057] If the processing circuit 1001 is dedicated hardware, it may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

[0058] When the processing circuit is a processor 1004, the functions of the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, and the drowsiness estimation unit 15 are realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in memory 1005. The processor 1004 executes the functions of the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, and the drowsiness estimation unit 15 by reading and executing the program stored in memory 1005. In other words, the drowsiness estimation device 1 includes memory 1005 for storing a program that, when executed by the processor 1004, will result in the execution of steps ST10 to ST50 in Figure 2 described above. Furthermore, the program stored in memory 1005 can be said to cause the computer to execute the processing procedures or methods of the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, and the drowsiness estimation unit 15. Here, memory 1005 refers to non-volatile or volatile semiconductor memory such as RAM, ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or magnetic disks, flexible disks, optical disks, compact disks, minidiscs, DVDs (Digital Versatile Discs), etc.

[0059] Furthermore, the functions of the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, and the drowsiness estimation unit 15 may be partially implemented by dedicated hardware and partially implemented by software or firmware. For example, the sensing unit 11 can be implemented by a processing circuit 1001 as dedicated hardware, while the functions of the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, and the drowsiness estimation unit 15 can be implemented by the processor 1004 reading and executing a program stored in memory 1005. Furthermore, the drowsiness estimation device 1 includes devices such as an imaging device 2, and an input interface device 1002 and an output interface device 1003 that perform wired or wireless communication.

[0060] In the above embodiment 1, the drowsiness estimation device 1 is an in-vehicle device mounted on a vehicle, and the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, and the drowsiness estimation unit 15 are provided in the drowsiness estimation device 1. The system is not limited to this configuration, however, a drowsiness estimation system may be configured with the in-vehicle device and the server, with some of the sensing unit 11, first noise factor detection unit 12, feature quantity calculation unit 13, drowsiness score calculation unit 14, and drowsiness estimation unit 15 being mounted on the vehicle's in-vehicle device, and the others being provided on a server connected to the in-vehicle device via a network. Alternatively, the sensing unit 11, the first noise factor detection unit 12, the feature calculation unit 13, the drowsiness score calculation unit 14, and the drowsiness estimation unit 15 may all be provided on the server.

[0061] Furthermore, in the above embodiment 1, the subject was, for example, the driver of a vehicle, but this is merely an example. The subject may be a passenger other than the driver of a vehicle. Also, the subject may be a passenger, including the driver, of a moving vehicle other than a vehicle, such as a bus, train, or airplane. The drowsiness estimation device 1 according to embodiment 1 can be applied as a drowsiness estimation device for estimating the drowsiness of passengers of a moving vehicle other than a vehicle.

[0062] As described above, according to Embodiment 1, the drowsiness estimation device 1 is configured to include: a sensing unit 11 that acquires drowsiness-related information indicating the state related to the occupant's drowsiness for each frame based on frames of captured images of the occupant's face of a moving vehicle; a first noise factor detection unit 12 that detects noise factor behaviors, which are actions by the occupant that involve eye movements and are similar to actions caused by drowsiness, based on the drowsiness-related information acquired by the sensing unit 11; a feature quantity calculation unit 13 that calculates drowsiness estimation features for estimating the occupant's drowsiness based on drowsiness-related information after the noise factor removal has been removed from the drowsiness-related information acquired by the sensing unit 11, which is the source of the drowsiness-related information that the first noise factor detection unit 12 used to detect the noise factor behavior; a drowsiness score calculation unit 14 that calculates a drowsiness score using the drowsiness estimation features calculated by the feature quantity calculation unit 13; and a drowsiness estimation unit 15 that estimates the occupant's drowsiness based on the drowsiness score calculated by the drowsiness score calculation unit 14. Therefore, when the drowsiness estimation device 1 estimates the drowsiness of the occupants of a mobile vehicle, it can prevent a decrease in the accuracy of the occupant's drowsiness estimation due to the occupant exhibiting behaviors similar to those that occur when drowsiness occurs.

[0063] Embodiment 2. There are certain driving conditions for a moving vehicle that are expected to reduce the likelihood of drowsiness among the occupants. If, under these driving conditions, it is presumed that the occupants are drowsy, this is a false presumption (overestimation). If an alarm is issued based on this false presumption, the alarm is an overreaction and may be bothersome to the occupants. Embodiment 2 describes an embodiment in which the estimated drowsiness of the occupants is corrected so as not to be overestimated when it is estimated from the driving state of the moving vehicle that drowsiness of the occupants is unlikely to occur. In the second embodiment described below, the target audience is assumed to be the vehicle driver.

[0064] Figure 6 shows an example of the configuration of the drowsiness estimation device 1a according to Embodiment 2. The drowsiness estimation device 1a according to Embodiment 2 is connected to a vehicle information acquisition device 3 in addition to the imaging device 2. The vehicle information acquisition device 3 outputs vehicle-related information (hereinafter referred to as "vehicle information") to the drowsiness estimation device 1a. Vehicle information includes vehicle speed information, information indicating whether the turn signals are being used on the vehicle (in other words, whether the turn signals are working), information indicating the amount the brakes are pressed, information indicating the steering angle, information indicating the accelerator pedal position, etc. The vehicle information acquisition device 3 includes, for example, a vehicle speed sensor for detecting the vehicle's speed, a turn signal sensor for detecting the operation status of the turn signals, a brake sensor for detecting the amount the brake pedal is pressed, a steering angle sensor for detecting the steering angle, and an accelerator sensor for detecting the accelerator pedal opening. In Figure 6, the drowsiness estimation device 1a is shown to be connected to one vehicle information acquisition device 3, but this is just one example, and multiple vehicle information acquisition devices 3 can be connected to the drowsiness estimation device 1a.

[0065] Regarding the configuration of the drowsiness estimation device 1a according to Embodiment 2, the same reference numerals are used for components that are the same as those in the drowsiness estimation device 1 described with reference to Figure 1 in Embodiment 1, and redundant explanations are omitted. The drowsiness estimation device 1a according to Embodiment 2 differs from the drowsiness estimation device 1 according to Embodiment 1 in that it includes a second noise factor detection unit 16 and a score correction unit 17.

[0066] The second noise factor detection unit 16 acquires vehicle information from the vehicle information acquisition device 3 and, based on the acquired vehicle information, detects the driving conditions of the vehicle that are expected to be less likely to cause drowsiness in the driver (hereinafter referred to as "noise factor driving conditions"). In Embodiment 2, the process performed by the second noise source detection unit 16 to detect the noise source driving state is referred to as the "second noise source detection process".

[0067] Examples of driving conditions that contribute to noise include, for example, when the vehicle is traveling at a low speed, when the turn signals are used frequently while the vehicle is in motion, when the brakes are used frequently, or when there are large changes in the steering angle of the vehicle. Furthermore, the specific vehicle driving conditions that constitute noise-generating driving conditions are predetermined by the administrator or other relevant parties.

[0068] When a vehicle is slowing down and driving at a low speed, or when the turn signals are being used frequently, for example, when the vehicle is approaching an intersection or about to change lanes, it is assumed that the driver is less likely to become drowsy. Furthermore, if a vehicle is frequently using its brakes, it can be inferred that it is, for example, stuck in traffic. Furthermore, if a vehicle is exhibiting significant changes in steering angle, it is presumed that, for example, the vehicle is in a parking lot or driving through an intersection.

[0069] Under the vehicle driving conditions described above, it is assumed that the driver is unlikely to experience drowsiness. Administrators and other relevant personnel should obtain such information in advance by conducting experiments or other means. The administrators then determine the aforementioned vehicle driving conditions, which are assumed to make it less likely for the driver to become drowsy, as "noise-causing driving conditions," and store information regarding these noise-causing driving conditions in a memory unit or other location where the noise-causing driving conditions can be accessed. The information regarding the noise-causing driving conditions is information that the second noise-causing detection unit 16 uses to determine the noise-causing driving conditions. For example, conditions for determining that a vehicle is in a noise-causing driving condition are set. These conditions for determining that a vehicle is in a noise-causing driving condition include, for example, the vehicle speed being below a preset threshold, the frequency of turn signal use during a preset period being above a preset threshold, the frequency of brake use during a preset period being above a preset threshold, and the amount of change in steering angle during a preset period being above a preset threshold.

[0070] The second noise factor detection unit 16 stores the vehicle information acquired from the vehicle information acquisition device 3 in a time-series format in a storage unit or the like. Based on the stored vehicle information, the second noise factor detection unit 16 can determine changes in the vehicle's driving state, such as changes in the steering angle.

[0071] When the second noise source detection unit 16 detects that the vehicle's driving state is a noise source driving state, it outputs information regarding the detected noise source driving state (hereinafter referred to as "noise source driving state information") to the score correction unit 17, along with the vehicle information acquired from the vehicle information acquisition device 3. The noise-causing driving condition information includes information indicating that the second noise-causing driving condition has been detected by the second noise-causing driving condition detection unit 16. The noise-causing driving condition information may further include information that allows for the identification of the type of noise-causing driving condition detected by the second noise-causing driving condition detection unit 16 (e.g., low-speed driving, frequent use of turn signals, frequent use of brakes, large changes in steering angle).

[0072] The score correction unit 17 corrects the drowsiness score calculated by the drowsiness score calculation unit 14 when the second noise factor detection unit 16 detects a noise factor driving condition. In Embodiment 2, the drowsiness score calculation unit 14 outputs the calculated driver's drowsiness score to the score correction unit 17. The score correction unit 17 corrects the drowsiness score according to predetermined rules (hereinafter referred to as "score correction rules"). The score correction rules are pre-set by the administrator or other relevant personnel and stored in a location accessible to the score correction unit 17, such as a memory unit. In Embodiment 2, the process performed by the score correction unit 17 to correct the drowsiness score is referred to as the "drowsiness score correction process."

[0073] A specific example of the correction of the drowsiness score by the score correction unit 17 in Embodiment 2 will be described. For example, suppose the score correction rule includes the rule, "If a noisy driving condition is detected, multiply the drowsiness score by 0.5." For example, suppose the drowsiness score calculated by the drowsiness score calculation unit 14 is "90". Also, suppose the second noise factor detection unit 16 detects that the frequency of turn signal use during a predetermined period is above a predetermined threshold, and therefore the vehicle is in a noisy driving state with frequent turn signal use. Furthermore, when the vehicle is frequently using its turn signals, it is possible that it is making frequent lane changes, for example. If such a driving condition is detected as a noise-generating driving condition, it is assumed that the driver is less likely to become drowsy. Nevertheless, the fact that the drowsiness score calculation unit 14 calculated a high drowsiness score of "90" suggests that, for example, when the driver frequently changes lanes, they check left and right, and this was considered an eye-closing action (i.e., an action that occurs when drowsiness occurs). In other words, the drowsiness score calculated by the drowsiness score calculation unit 14 may be incorrect. In this case, the score correction unit 17 corrects the drowsiness score to "45".

[0074] For example, suppose the drowsiness estimation unit 15 is configured to estimate "drowsiness present" if the drowsiness score exceeds "50". In this case, if the drowsiness score is "90", the drowsiness estimation unit 15 will estimate "drowsiness present". Then, for example, an alarm device (not shown) will output an alarm based on the drowsiness estimation result of the drowsiness estimation unit 15, which is "drowsiness present". In the example described above, if the score correction unit 17 does not correct the drowsiness score, a drowsiness warning will be output to the driver even though it is assumed that the driver is not drowsy. The score correction unit 17 corrects the drowsiness score when the second noise factor detection unit 16 detects that the vehicle is in a noisy driving state. This prevents the drowsiness estimation unit 15 from overestimating the driver's drowsiness and suppresses the over-warnings described above.

[0075] The examples mentioned above are just a few examples. The score correction rules may differ from those given in the example above. Furthermore, score correction rules may be set up to adjust the degree to which the drowsiness score is corrected depending on the type of noise-causing driving conditions. For example, the score correction rules could include the following: "If a noisy driving condition is detected, such as frequent use of turn signals, the drowsiness score is multiplied by 0.5; if a noisy driving condition is detected, such as low-speed driving, the drowsiness score is multiplied by 0.7."

[0076] The score correction unit 17 outputs the corrected drowsiness score (hereinafter referred to as the "corrected drowsiness score") to the drowsiness estimation unit 15. The drowsiness estimation unit 15 estimates the driver's drowsiness based on the corrected drowsiness score.

[0077] The operation of the drowsiness estimation device 1a according to Embodiment 2 will be described. Figure 7 is a flowchart illustrating the operation of the drowsiness estimation device 1a according to Embodiment 2. For example, when the vehicle's power is turned on and an image is output from the imaging device 2, the drowsiness estimation device 1a repeats the operation shown in the flowchart of Figure 7 until the vehicle's power is turned off. The specific operations in steps ST10 to ST40 and step ST50 in Figure 7 are the same as the specific operations in steps ST10 to ST40 and step ST50 in Figure 2, which were explained in Embodiment 1. Therefore, the same step numbers are used and redundant explanations are omitted.

[0078] The second noise source detection unit 16 acquires vehicle information from the vehicle information acquisition device 3 and performs a second noise source detection process to detect noise source driving conditions based on the acquired vehicle information (step ST60). If the second noise source detection unit 16 detects that the vehicle's driving state is a noise source driving state, it outputs the noise source driving state information, along with the vehicle information acquired from the vehicle information acquisition device 3, to the score correction unit 17. Furthermore, if the second noise factor detection unit 16 does not detect that the vehicle's driving state is a noise-generating driving state, it may output information to the score correction unit 17 indicating that it did not detect that the vehicle is in a noise-generating driving state, or it may choose not to output anything to the score correction unit 17.

[0079] If the second noise factor detection unit 16 detects a noise factor driving condition in step ST60, the score correction unit 17 performs a drowsiness score correction process to correct the drowsiness score calculated by the drowsiness score calculation unit 14 (step ST45). The score correction unit 17 outputs the corrected drowsiness score to the drowsiness estimation unit 15.

[0080] Note that in the flowchart in Figure 7, the processes in steps ST10 to ST40 and the process in step ST60 are assumed to be performed in parallel, but this is only one example. For example, the drowsiness estimation device 1a may perform the process in step ST60 after the processing in steps ST10 to ST40. It is sufficient that steps ST10 to ST40 and step ST60 have been completed before step ST45 is processed.

[0081] In this way, the drowsiness estimation device 1a acquires drowsiness-related information frame by frame based on the frame of the captured image of the driver's face, and detects noise factor behaviors by the driver that are similar to behaviors caused by drowsiness based on the acquired drowsiness-related information. The drowsiness estimation device 1a calculates drowsiness estimation features based on the drowsiness-related information after removing the drowsiness-related information that was the source of the detection of noise factor behaviors from the acquired drowsiness-related information. Then, the drowsiness estimation device 1a calculates a drowsiness score using the drowsiness estimation features, and estimates the driver's drowsiness based on the calculated drowsiness score. Furthermore, the drowsiness estimation device 1a corrects the calculated drowsiness score if it detects a noisy driving condition based on vehicle information. If the drowsiness score has been corrected, the drowsiness estimation device 1a estimates the driver's drowsiness based on the corrected drowsiness score. Therefore, the drowsiness estimation device 1a can prevent a decrease in the accuracy of estimating a driver's drowsiness due to the driver engaging in noise-generating behaviors. More specifically, it can prevent a decrease in the accuracy of estimating a driver's drowsiness due to the use of noise-generating features in the estimation of a driver's drowsiness, thereby enabling highly accurate drowsiness estimation and preventing overestimation of driver drowsiness.

[0082] The hardware configuration of the drowsiness estimation device 1a according to Embodiment 2 is the same as the hardware configuration of the drowsiness estimation device 1 described using Figures 5A and 5B in Embodiment 1, so it is omitted from the illustration. In Embodiment 2, the functions of the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, the drowsiness estimation unit 15, the second noise factor detection unit 16, and the score correction unit 17 are realized by the processing circuit 1001. That is, the drowsiness estimation device 1a includes a processing circuit 1001 for controlling the estimation of driver drowsiness by using feature quantities calculated based on captured images acquired from the imaging device 2, excluding feature quantities calculated due to the driver engaging in noise factor behavior, as drowsiness estimation feature quantities, and for correcting the drowsiness score based on vehicle information acquired from the vehicle information acquisition device 3. The processing circuit 1001 reads and executes the program stored in the memory 1005, thereby executing the functions of the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, the drowsiness estimation unit 15, the second noise factor detection unit 16, and the score correction unit 17. In other words, the drowsiness estimation device 1a includes a memory 1005 for storing a program that, when executed by the processing circuit 1001, will result in the execution of steps ST10 to ST60 in Figure 7 described above. It can also be said that the program stored in the memory 1005 causes the computer to execute the procedures or methods of the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, the drowsiness estimation unit 15, the second noise factor detection unit 16, and the score correction unit 17. The drowsiness estimation device 1a includes devices such as an imaging device 2 and a vehicle information acquisition device 3, as well as an input interface device 1002 and an output interface device 1003 that perform wired or wireless communication.

[0083] In the above embodiment 2, the drowsiness estimation device 1a is an in-vehicle device mounted on a vehicle, and the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, the drowsiness estimation unit 15, the second noise factor detection unit 16, and the score correction unit 17 are provided in the drowsiness estimation device 1a. The system is not limited to this configuration, however, a drowsiness estimation system may be configured with the in-vehicle device and the server, with some of the sensing unit 11, first noise factor detection unit 12, feature quantity calculation unit 13, drowsiness score calculation unit 14, drowsiness estimation unit 15, second noise factor detection unit 16, and score correction unit 17 being mounted on the vehicle's in-vehicle device, and the others being provided on a server connected to the in-vehicle device via a network. Alternatively, the sensing unit 11, the first noise factor detection unit 12, the feature calculation unit 13, the drowsiness score calculation unit 14, the drowsiness estimation unit 15, the second noise factor detection unit 16, and the score correction unit 17 may all be provided on the server.

[0084] Furthermore, in the above embodiment 2, the subject was, for example, the driver of a vehicle, but this is merely an example. The subject may be a passenger other than the driver of a vehicle. Alternatively, the subject may be a passenger, including the driver, of a moving vehicle other than a vehicle, such as a bus, train, or airplane. The drowsiness estimation device 1a according to embodiment 2 can be applied as a drowsiness estimation device for estimating the drowsiness of passengers of a moving vehicle other than a vehicle.

[0085] As described above, according to Embodiment 2, the drowsiness estimation device 1a is configured to include: a sensing unit 11 that acquires drowsiness-related information indicating the state related to the occupant's drowsiness for each frame based on frames of captured images of the occupant's face of a moving vehicle; a first noise factor detection unit 12 that detects noise factor behaviors, which are actions by the occupant that involve eye movements and are similar to actions caused by drowsiness, based on the drowsiness-related information acquired by the sensing unit 11; a feature quantity calculation unit 13 that calculates drowsiness estimation features for estimating the occupant's drowsiness based on drowsiness-related information after the noise factor removal has been removed from the drowsiness-related information acquired by the sensing unit 11, which is the source of the drowsiness-related information that the first noise factor detection unit 12 used to detect the noise factor behavior; a drowsiness score calculation unit 14 that calculates a drowsiness score using the drowsiness estimation features calculated by the feature quantity calculation unit 13; and a drowsiness estimation unit 15 that estimates the occupant's drowsiness based on the drowsiness score calculated by the drowsiness score calculation unit 14. Therefore, when the sleepiness estimation device 1a estimates the sleepiness of the occupants of a mobile vehicle, it can prevent a decrease in the accuracy of the occupant's sleepiness estimation due to the occupant exhibiting behaviors similar to those that occur when sleepiness occurs.

[0086] Furthermore, the drowsiness estimation device 1a includes a second noise factor detection unit 16 that detects a noise factor driving state, which is a driving state of the moving vehicle that is assumed to be less likely to cause drowsiness in the occupant, based on moving vehicle information related to the moving vehicle, and a score correction unit 17 that corrects the drowsiness score calculated by the drowsiness score calculation unit 14 when the second noise factor detection unit 16 detects a noise factor driving state. The drowsiness estimation unit 15 is configured to estimate the occupant's drowsiness based on the corrected drowsiness score after the score correction unit 17 has corrected the drowsiness score calculated by the drowsiness score calculation unit 14. As a result, the drowsiness estimation device 1a can prevent overestimation of the occupant's drowsiness.

[0087] Embodiment 3. In Embodiment 2, the drowsiness estimation device detected a noisy driving condition based on vehicle information, and corrected the drowsiness score when it detected a noisy driving condition, thereby preventing misestimation (overestimation) of drowsiness. On the other hand, malfunctions in the sensing unit can also lead to misestimation of drowsiness. For example, even if a vehicle driver is driving with their eyes open and their eye behavior is normal, a mistake in the sensing unit's sensing process may cause it to mistakenly detect that the driver's eyes are closed, resulting in the acquisition of incorrect drowsiness-related information. If the feature calculation unit were to calculate drowsiness estimation features based on this incorrect drowsiness-related information, it might calculate drowsiness estimation features that could, for example, estimate "drowsiness present." As a result, the drowsiness estimation unit could overestimate the driver's drowsiness. Embodiment 3 describes an embodiment that corrects the drowsiness score, taking into account the possibility of errors in the sensing process by such a sensing unit. In the third embodiment described below, the target audience is assumed to be the vehicle driver.

[0088] Figure 8 shows an example of the configuration of the drowsiness estimation device 1b according to Embodiment 3. Regarding the configuration of the drowsiness estimation device 1b according to Embodiment 3, the same reference numerals are used for components that are the same as those in the drowsiness estimation device 1 described with reference to Figure 1 in Embodiment 1, and redundant explanations are omitted. The drowsiness estimation device 1b according to Embodiment 3 differs from the drowsiness estimation device 1 according to Embodiment 1 in that it includes a third noise factor detection unit 18 and a score correction unit 17.

[0089] The third noise factor detection unit 18 detects the occurrence of an event (hereinafter referred to as "noise factor sensing") in which the sensing unit 11 is presumed to have misidentified a state related to occupant drowsiness, based on the drowsiness-related information acquired by the sensing unit 11. In Embodiment 3, the sensing unit 11 outputs the sensing results to the first noise factor detection unit 12 and the third noise factor detection unit 18. In Embodiment 3, the process performed by the third noise factor detection unit 18 to detect noise factor sensing is referred to as the "third noise factor detection process".

[0090] One example of noise factor sensing is the erroneous acquisition of drowsiness-related information due to the sensing unit 11 mistakenly detecting that the driver's eyes are closed, or in other words, that their eyelids are only slightly open, even though they are actually open. Such erroneous acquisition of drowsiness-related information may lead to an erroneous estimation of the driver's drowsiness when the drowsiness estimation unit 15 estimates the driver's drowsiness based on the drowsiness-related information. The third noise factor detection unit 18 detects whether the above-mentioned noise factor sensing is occurring, for example, based on the time-series sleepiness-related information acquired by the sensing unit 11, by determining whether or not sleepiness-related information that can be determined to be an extremely long period of continuous eye closure has been acquired. The third noise factor detection unit 18 detects that the above-mentioned noise factor sensing is occurring if sleepiness-related information that can be determined to be an extremely long period of continuous eye closure has been acquired. For example, the third noise factor detection unit 18 detects that if a state determined to be eye-closed, or more specifically, a state in which the degree of eyelid opening is below a preset threshold (hereinafter referred to as the "degree of eyelid opening for continuous eye-closing determination"), continues for a preset period (hereinafter referred to as the "period for continuous eye-closing determination"), based on time-series sleepiness-related information, then sleepiness-related information that could be considered to be extremely long-lasting eye-closing has been acquired, that is, noise factor sensing has occurred. The degree of eyelid opening for continuous eye-closing determination and the period for continuous eye-closing determination are predetermined by an administrator or the like and stored in a location accessible to the third noise factor detection unit 18. The third noise factor detection unit 18 only needs to acquire time-series sleepiness-related information from the sensing results stored in the memory unit.

[0091] Another example of noise factor sensing is the erroneous acquisition of drowsiness-related information due to repeated erroneous detections by the sensing unit 11, such as falsely detecting that the driver's eyes are closed when they are actually open, and falsely detecting that the driver's eyes are open when they are actually closed. Such erroneous acquisition of drowsiness-related information may lead to an erroneous estimation of the driver's drowsiness when the drowsiness estimation unit 15 estimates the driver's drowsiness based on the drowsiness-related information. The third noise factor detection unit 18 detects whether the above-mentioned noise factor sensing is occurring, for example, based on the time-series sleepiness-related information acquired by the sensing unit 11, by determining whether or not sleepiness-related information that can be determined to indicate an extremely high number of blinks has been acquired. The third noise factor detection unit 18 detects that the above-mentioned noise factor sensing is occurring if sleepiness-related information that can be determined to indicate an extremely high number of blinks has been acquired. For example, the third noise factor detection unit 18 detects the driver's blinks based on time-series drowsiness-related information using a known blink detection method. If the third noise factor detection unit 18 detects more than a predetermined number of blinks (hereinafter referred to as the "blink count determination threshold") within a predetermined period (hereinafter referred to as the "blink judgment period"), it detects that drowsiness-related information that can be judged as an extremely high number of blinks has been acquired, that is, that noise factor sensing is occurring. The blink judgment period and the blink count determination threshold are predetermined by an administrator or the like and stored in a location accessible to the third noise factor detection unit 18.

[0092] It should be noted that the above examples are merely illustrations, and the conditions for the third noise factor detection unit 18 to detect that noise factor sensing is occurring based on the drowsiness-related information acquired by the sensing unit 11 are determined in advance by the administrator or other appropriate personnel.

[0093] When the third noise factor detection unit 18 detects that noise factor sensing is occurring, it outputs information regarding the detected noise factor sensing (hereinafter referred to as "noise factor sensing information") along with the sensing result to the score correction unit 17. The noise factor sensing information includes information indicating that the third noise factor detection unit 18 has detected that noise factor sensing is occurring. The noise factor sensing information may further include information that allows for the identification of the type of noise factor sensing detected by the third noise factor detection unit 18 (e.g., extreme continuous eye closure, extremely frequent blinking).

[0094] When the third noise factor detection unit 18 detects noise factor sensing, the score correction unit 17 corrects the drowsiness score calculated by the drowsiness score calculation unit 14 based on the noise factor sensing. In Embodiment 3, the drowsiness score calculation unit 14 outputs the calculated driver drowsiness score to the score correction unit 17. The score correction unit 17 corrects the drowsiness score according to predetermined score correction rules. In Embodiment 3, the process performed by the score correction unit 17 to correct the drowsiness score is referred to as the "drowsiness score correction process."

[0095] A specific example of the correction of the drowsiness score by the score correction unit 17 in Embodiment 3 will be described. For example, suppose the score correction rule is set to "multiply the drowsiness score by 0.5 if noise source sensing is detected." For example, suppose the drowsiness score calculated by the drowsiness score calculation unit 14 is "90". Also, suppose the third noise factor detection unit 18 detects, based on the drowsiness-related information acquired from the sensing unit 11, that the eyelid opening degree has remained below the eyelid opening degree for continuous eye closure determination for a continuous eye closure determination period (e.g., 10 seconds), and that noise factor sensing, which is the acquisition of drowsiness-related information that could be considered an extremely long period of continuous eye closure, has occurred. Closing one's eyes continuously for 10 seconds is abnormal, but despite this abnormal state, the fact that the sleepiness score calculation unit 14 calculated a high sleepiness score of "90" suggests that the abnormal state of continuous eye closure may have been considered a state of sleepiness, and that the feature calculation unit 13 may have calculated features that could lead to a high sleepiness score. In other words, the sleepiness score calculated by the sleepiness score calculation unit 14 may be incorrect. In this case, the score correction unit 17 corrects the drowsiness score to "45".

[0096] For example, the drowsiness estimation unit 15 estimates "drowsiness present" if the drowsiness score exceeds "50". In this case, if the drowsiness score is "90", the drowsiness estimation unit 15 estimates "drowsiness present". Then, for example, an alarm device (not shown) outputs an alarm based on the drowsiness estimation result of the drowsiness estimation unit 15, which is "drowsiness present". In the example described above, if the score correction unit 17 does not correct the drowsiness score, a drowsiness warning will be output to the driver even though it is assumed that the driver is not drowsy. The score correction unit 17 corrects the drowsiness score when the third noise factor detection unit 18 detects that a noise factor is being sensed. This prevents the drowsiness estimation unit 15 from overestimating the driver's drowsiness and suppresses the over-alerts described above.

[0097] The examples mentioned above are just a few examples. The score correction rules may differ from those given in the example above. Furthermore, score correction rules may be set up to adjust the degree to which the drowsiness score is corrected depending on the type of noise factor sensing, for example. For example, the score correction rule may include the following: "If noise factor sensing, which is the misacquisition of sleepiness-related information that may be interpreted as an extremely long period of continuous eye closure, is detected, multiply the sleepiness score by 0.5; if noise factor sensing, which is the misacquisition of sleepiness-related information that may be interpreted as an extremely high number of blinks, is detected, multiply the sleepiness score by 0.7."

[0098] The score correction unit 17 outputs the corrected drowsiness score to the drowsiness estimation unit 15. The drowsiness estimation unit 15 estimates the driver's drowsiness based on the corrected drowsiness score.

[0099] The operation of the drowsiness estimation device 1b according to Embodiment 3 will be described below. Figure 9 is a flowchart illustrating the operation of the drowsiness estimation device 1b according to Embodiment 3. For example, when the vehicle's power is turned on and an image is output from the imaging device 2, the drowsiness estimation device 1b repeats the operations shown in the flowchart of Figure 9 until the vehicle's power is turned off. The specific operations in steps ST10 to ST40 and step ST50 in Figure 9 are the same as the specific operations in steps ST10 to ST40 and step ST50 in Figure 2, which were explained in Embodiment 1. Therefore, the same step numbers are used and redundant explanations are omitted.

[0100] The third noise factor detection unit 18 acquires drowsiness-related information from the sensing unit 11 and performs a third noise factor detection process to detect the occurrence of noise factor sensing based on the acquired drowsiness-related information (step ST70). When the third noise factor detection unit 18 detects the occurrence of a noise factor sensing, it outputs the noise factor sensing information, along with the drowsiness-related information, from the sensing unit 11 to the score correction unit 17. Furthermore, if the third noise factor detection unit 18 does not detect the occurrence of noise factor sensing, it may output information to the score correction unit 17 indicating that it did not detect the occurrence of noise factor sensing, or it may choose not to output anything to the score correction unit 17.

[0101] If the third noise factor detection unit 18 detects noise factor sensing in step ST70, the score correction unit 17 performs a sleepiness score correction process to correct the sleepiness score calculated by the sleepiness score calculation unit 14 based on the noise factor sensing (step ST45). The score correction unit 17 outputs the corrected drowsiness score to the drowsiness estimation unit 15.

[0102] Note that in the flowchart in Figure 9, the processes in steps ST10 to ST40 and the process in step ST70 are shown to be performed in parallel, but this is only one example. For example, the drowsiness estimation device 1b may perform the process in step ST70 after the processing in steps ST10 to ST40. It is sufficient that steps ST10 to ST40 and step ST70 have been completed before step ST45 is processed.

[0103] In this way, the drowsiness estimation device 1b acquires drowsiness-related information frame by frame based on the captured image of the driver's face, and detects noise factor behaviors by the driver that are similar to behaviors caused by drowsiness based on the acquired drowsiness-related information. The drowsiness estimation device 1b calculates drowsiness estimation features based on the drowsiness-related information after removing the drowsiness-related information that was the source of the detection of noise factor behaviors from the acquired drowsiness-related information. Then, the drowsiness estimation device 1b calculates a drowsiness score using the drowsiness estimation features, and estimates the driver's drowsiness based on the calculated drowsiness score. Furthermore, the drowsiness estimation device 1b corrects the drowsiness score if it detects the occurrence of noise factor sensing based on drowsiness-related information. If the drowsiness score has been corrected, the drowsiness estimation device 1b estimates the driver's drowsiness based on the corrected drowsiness score. Therefore, the drowsiness estimation device 1b can prevent a decrease in the accuracy of estimating a driver's drowsiness due to the driver engaging in noise-generating behaviors. More specifically, it can prevent a decrease in the accuracy of estimating a driver's drowsiness due to the use of noise-generating features in the driver's drowsiness estimation, thereby enabling highly accurate drowsiness estimation and preventing overestimation of driver drowsiness.

[0104] The hardware configuration of the drowsiness estimation device 1b according to Embodiment 3 is the same as the hardware configuration of the drowsiness estimation device 1 described using Figures 5A and 5B in Embodiment 1, so it is omitted from the illustration. In Embodiment 3, the functions of the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, the drowsiness estimation unit 15, the score correction unit 17, and the third noise factor detection unit 18 are realized by the processing circuit 1001. That is, the drowsiness estimation device 1b includes a processing circuit 1001 for controlling the estimation of the driver's drowsiness based on the captured image acquired from the imaging device 2, using the feature quantity calculated due to the driver engaging in noise factor behavior as the drowsiness estimation feature quantity, and for correcting the drowsiness score based on drowsiness-related information acquired based on the captured image. The processing circuit 1001 reads and executes the program stored in the memory 1005, thereby executing the functions of the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, the drowsiness estimation unit 15, the score correction unit 17, and the third noise factor detection unit 18. In other words, when the drowsiness estimation device 1b is executed by the processing circuit 1001, it performs steps ST10 to ST50 and step ST in Figure 7 described above. 6 The system includes a memory 1005 for storing a program that will ultimately be executed. Furthermore, the program stored in memory 1005 can be said to cause the computer to execute the procedures or methods of the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, the drowsiness estimation unit 15, the score correction unit 17, and the third noise factor detection unit 18. The drowsiness estimation device 1b includes devices such as an imaging device 2, and an input interface device 1002 and an output interface device 1003 that perform wired or wireless communication.

[0105] In the above embodiment 3, the drowsiness estimation device 1b is an in-vehicle device mounted on a vehicle, and the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, the drowsiness estimation unit 15, the score correction unit 17, and the third noise factor detection unit 18 are provided in the drowsiness estimation device 1b. The system is not limited to this configuration, however, a drowsiness estimation system may be configured using an in-vehicle device and a server, with some of the sensing unit 11, first noise factor detection unit 12, feature quantity calculation unit 13, drowsiness score calculation unit 14, drowsiness estimation unit 15, score correction unit 17, and third noise factor detection unit 18 mounted on an in-vehicle device, and the others provided on a server connected to the in-vehicle device via a network. Alternatively, the sensing unit 11, the first noise factor detection unit 12, the feature quantity calculation unit 13, the drowsiness score calculation unit 14, the drowsiness estimation unit 15, the score correction unit 17, and the third noise factor detection unit 18 may all be provided on the server.

[0106] Furthermore, in the above embodiment 3, the subject was, for example, the driver of a vehicle, but this is merely an example. The subject may be a passenger other than the driver of a vehicle. Also, the subject may be a passenger, including the driver, of a moving vehicle other than a vehicle, such as a bus, train, or airplane. Embodiment 3 The sleepiness estimation device 1b can be applied as a sleepiness estimation device for estimating sleepiness in occupants of moving objects other than vehicles.

[0107] As described above, according to Embodiment 3, the drowsiness estimation device 1b is configured to include: a sensing unit 11 that acquires drowsiness-related information indicating the state related to the occupant's drowsiness for each frame based on frames of captured images of the occupant's face of a moving vehicle; a first noise factor detection unit 12 that detects noise factor behaviors, which are actions by the occupant that involve eye movements and are similar to actions caused by drowsiness, based on the drowsiness-related information acquired by the sensing unit 11; a feature quantity calculation unit 13 that calculates drowsiness estimation features for estimating the occupant's drowsiness based on drowsiness-related information after the noise factor removal has been removed from the drowsiness-related information acquired by the sensing unit 11, which is the source of the drowsiness-related information that the first noise factor detection unit 12 used to detect the noise factor behavior; a drowsiness score calculation unit 14 that calculates a drowsiness score using the drowsiness estimation features calculated by the feature quantity calculation unit 13; and a drowsiness estimation unit 15 that estimates the occupant's drowsiness based on the drowsiness score calculated by the drowsiness score calculation unit 14. Therefore, when the drowsiness estimation device 1b estimates the drowsiness of the occupants of a mobile vehicle, it can prevent a decrease in the accuracy of the occupant's drowsiness estimation due to the occupant exhibiting behaviors similar to those that occur when drowsiness occurs.

[0108] Furthermore, the drowsiness estimation device 1b includes a third noise factor detection unit 18 that detects the occurrence of noise factor sensing, which is an event in which the sensing unit 11 is presumed to have mis-detected a state related to the occupant's drowsiness and thus mis-acquired drowsiness-related information, based on the drowsiness-related information acquired by the sensing unit 11, and a score correction unit 17 that corrects the drowsiness score calculated by the drowsiness score calculation unit 14 when the third noise factor detection unit 18 detects the occurrence of noise factor sensing. The drowsiness estimation unit 15 is configured to estimate the occupant's drowsiness based on the corrected drowsiness score after the score correction unit 17 has corrected the drowsiness score calculated by the drowsiness score calculation unit 14. Therefore, the drowsiness estimation device 1b can prevent overestimation of the occupant's drowsiness.

[0109] The drowsiness estimation device may also be configured by combining the configurations of the drowsiness estimation device 1 according to Embodiment 1, the drowsiness estimation device 1a according to Embodiment 2, and the drowsiness estimation device 1b according to Embodiment 3. Figure 10 shows an example configuration of a sleepiness estimation device 1c, which combines the configurations of the sleepiness estimation device 1 according to Embodiment 1, the sleepiness estimation device 1a according to Embodiment 2, and the sleepiness estimation device 1b according to Embodiment 3. Figure 11 is a flowchart illustrating the operation of a sleepiness estimation device 1c, which combines the configurations of the sleepiness estimation device 1 according to Embodiment 1, the sleepiness estimation device 1a according to Embodiment 2, and the sleepiness estimation device 1b according to Embodiment 3.

[0110] Thus, the drowsiness estimation device 1c includes a sensing unit 11 that acquires drowsiness-related information indicating the occupant's drowsiness state for each frame based on frames of captured images of the occupant's face (e.g., driver) of a moving object (e.g., vehicle), and a first noise factor detection unit 12 that detects noise factor behaviors by the occupant based on the drowsiness-related information acquired by the sensing unit 11. Based on the drowsiness-related information acquired by the sensing unit 11, the first noise factor detection unit 12 removes the drowsiness-related information that was the basis for detecting noise factor behaviors, resulting in drowsiness-related information after noise factor removal. A feature calculation unit 13 calculates drowsiness estimation features for estimating occupant drowsiness, a drowsiness score calculation unit 14 calculates a drowsiness score using the drowsiness estimation features calculated by the feature calculation unit 13, a drowsiness estimation unit 15 estimates occupant drowsiness based on the drowsiness score calculated by the drowsiness score calculation unit 14, and a second noise factor detection unit 16 detects noise factor driving conditions that are assumed to be unlikely to cause drowsiness in the occupant (e.g., driver) based on mobile information (vehicle information) related to the moving object (e.g., vehicle), and the sensing unit 11 acquires drowsiness-related information. The system includes a third noise factor detection unit 18 that detects the occurrence of noise factor sensing, which is an event in which the sensing unit 11 is presumed to have misidentified a state related to occupant drowsiness and thus misidentified drowsiness-related information based on drowsiness-related information acquired by the sensing unit 11, and a score correction unit 17 that corrects the drowsiness score calculated by the drowsiness score calculation unit 14 based on the noise factor driving state or the occurrence of noise factor sensing when the second noise factor detection unit 16 detects a noise factor driving state or when the third noise factor detection unit 18 detects the occurrence of noise factor sensing, and the drowsiness estimation unit 15 can be configured to estimate occupant drowsiness based on the corrected drowsiness score after the score correction unit 17 has corrected it. As a result, the drowsiness estimation device 1c can prevent a decrease in the accuracy of estimating a crew member's drowsiness due to the crew member engaging in noise-generating behavior. More specifically, it can prevent a decrease in the accuracy of estimating a crew member's drowsiness due to the use of noise-generating features, enabling highly accurate drowsiness estimation and preventing overestimation of crew member drowsiness.

[0111] In the drowsiness estimation device 1c, the score correction rule used by the score correction unit 17 when correcting the drowsiness score is set to a rule that takes into account both the noise factor driving conditions and the occurrence of noise factor sensing. For example, the score correction rule might include the following: "If a noisy driving condition is detected, multiply the drowsiness score by 0.5. If the occurrence of a noise-causing sensing is detected, multiply the drowsiness score by 0.5. If both a noisy driving condition and the occurrence of a noise-causing sensing are detected, correct the drowsiness score by the product of the multiplier corresponding to the noisy driving condition (i.e., 0.5) and the multiplier corresponding to the occurrence of a noise-causing sensing (i.e., 0.5)." Furthermore, for example, the score correction rule may include the following rule: "If a noisy driving condition is detected, multiply the drowsiness score by 0.5. If the occurrence of a noise-causing sensing is detected, multiply the drowsiness score by 0.5. If both a noisy driving condition and the occurrence of a noise-causing sensing are detected, correct the drowsiness score according to the weights set for the noisy driving condition and the noise-causing sensing." The weights assigned to different noise-generating driving conditions and noise-generating sensing conditions are predetermined by the administrator or other relevant parties. This allows the sleepiness estimation device 1c to further enhance the correction effect of the sleepiness score.

[0112] Furthermore, it is possible to freely combine the embodiments, modify any component of each embodiment, or omit any component in each embodiment. [Industrial applicability]

[0113] The drowsiness estimation device of this disclosure can prevent a decrease in the accuracy of estimating the drowsiness of an occupant of a mobile vehicle due to the occupant exhibiting behaviors that have similar characteristics to those that occur when drowsiness occurs. [Explanation of Symbols]

[0114] 1, 1a, 1b, 1c Drowsiness estimation device, 2 Imaging device, 3 Vehicle information acquisition device, 11 Sensing unit, 12 First noise factor detection unit, 13 Feature calculation unit, 131 Sensing result selection unit, 14 Drowsiness score calculation unit, 15 Drowsiness estimation unit, 16 Second noise factor detection unit, 17 Score correction unit, 18 Third noise factor detection unit, 1001 Processing circuit, 1002 Input interface device, 1003 Output interface device, 1004 Processor, 1005 Memory.

Claims

1. A sensing unit that acquires sleepiness-related information indicating the state of sleepiness of the occupant for each frame based on the frames of captured images of the occupant's face of the moving vehicle, Based on the drowsiness-related information acquired by the sensing unit, a first noise factor detection unit detects noise factor behaviors, which are actions by the occupant that involve eye movements and are similar to actions caused by drowsiness. A feature calculation unit calculates a feature quantity for estimating the drowsiness of the occupant based on the drowsiness-related information obtained by the sensing unit, which is obtained by removing the drowsiness-related information obtained by the first noise factor detection unit from the drowsiness-related information that was the basis for the detection of the noise factor behavior by the sensing unit, A sleepiness score calculation unit calculates a sleepiness score using the sleepiness estimation features calculated by the feature calculation unit, A sleepiness estimation unit estimates the sleepiness of the occupant based on the sleepiness score calculated by the sleepiness score calculation unit. Equipped with, The aforementioned noise-generating behaviors include downward viewing, The first noise factor detection unit detects that the occupant was looking downwards if, based on the time-series drowsiness-related information, the occupant's gaze direction changes downwards by an angle greater than or equal to the downward-looking determination angle during the downward-looking determination period. A sleepiness estimation device characterized by the following features.

2. A sensing unit that acquires sleepiness-related information indicating a state related to sleepiness of the occupant of a mobile vehicle, based on frames of captured images of the occupant's face, for each frame, Based on the drowsiness-related information acquired by the sensing unit, a first noise factor detection unit detects noise factor behaviors, which are actions by the occupant that involve eye movements and are similar to actions caused by drowsiness. A feature calculation unit calculates a feature quantity for estimating the drowsiness of the occupant based on the drowsiness-related information obtained by the sensing unit, which is obtained by removing the drowsiness-related information obtained by the first noise factor detection unit from the drowsiness-related information that was the basis for the detection of the noise factor behavior by the sensing unit, A sleepiness score calculation unit calculates a sleepiness score using the sleepiness estimation features calculated by the feature calculation unit, A sleepiness estimation unit estimates the sleepiness of the occupant based on the sleepiness score calculated by the sleepiness score calculation unit, A second noise factor detection unit detects a noise factor driving state, which is a driving state of the moving body that is assumed to be less likely to cause drowsiness in the occupant, based on the moving body information related to the moving body. When the second noise factor detection unit detects the noise factor driving condition, the system includes a score correction unit that corrects the drowsiness score calculated by the drowsiness score calculation unit. The drowsiness estimation unit, when the score correction unit corrects the drowsiness score calculated by the drowsiness score calculation unit, estimates the drowsiness of the occupant based on the corrected drowsiness score after the score correction unit has corrected it. A sleepiness estimation device characterized by the following features.

3. The aforementioned noise-causing driving conditions include: the moving body is traveling at a low speed; the turn signals are used frequently while the moving body is traveling; the brakes are used frequently while the moving body is traveling; or the steering angle of the moving body changes significantly. The sleepiness estimation device according to claim 2.

4. A sensing unit that acquires sleepiness-related information indicating a state related to sleepiness of the occupant of a mobile vehicle, based on frames of captured images of the occupant's face, for each frame, Based on the drowsiness-related information acquired by the sensing unit, a first noise factor detection unit detects noise factor behaviors, which are actions by the occupant that involve eye movements and are similar to actions caused by drowsiness. A feature calculation unit calculates a feature quantity for estimating the drowsiness of the occupant based on the drowsiness-related information obtained by the sensing unit, which is obtained by removing the drowsiness-related information obtained by the first noise factor detection unit from the drowsiness-related information that was the basis for the detection of the noise factor behavior by the sensing unit, A sleepiness score calculation unit calculates a sleepiness score using the sleepiness estimation features calculated by the feature calculation unit, A sleepiness estimation unit estimates the sleepiness of the occupant based on the sleepiness score calculated by the sleepiness score calculation unit, A third noise factor detection unit detects the occurrence of noise factor sensing, which is an event in which the sensing unit is presumed to have misidentified the sleepiness-related information due to a misdetection of the sleepiness-related state of the occupant, based on the sleepiness-related information acquired by the sensing unit, When the third noise factor detection unit detects the occurrence of the noise factor sensing, the score correction unit corrects the drowsiness score calculated by the drowsiness score calculation unit. The drowsiness estimation unit, when the score correction unit corrects the drowsiness score calculated by the drowsiness score calculation unit, estimates the drowsiness of the occupant based on the corrected drowsiness score after the score correction unit has corrected it. A sleepiness estimation device characterized by the following features.

5. The third noise factor detection unit detects that noise factor sensing has occurred when the sensing unit has acquired sleepiness-related information that can be determined to indicate a long period of continuous eye closure, or when the sensing unit has acquired sleepiness-related information that can be determined to indicate a high number of blinks. The sleepiness estimation device according to feature 4.

6. A sensing unit that acquires sleepiness-related information indicating a state related to sleepiness of the occupant of a mobile vehicle, based on frames of captured images of the occupant's face, for each frame, Based on the drowsiness-related information acquired by the sensing unit, a first noise factor detection unit detects noise factor behaviors, which are actions by the occupant that involve eye movements and are similar to actions caused by drowsiness. A feature calculation unit calculates a feature quantity for estimating the drowsiness of the occupant based on the drowsiness-related information obtained by the sensing unit, which is obtained by removing the drowsiness-related information obtained by the first noise factor detection unit from the drowsiness-related information that was the basis for the detection of the noise factor behavior by the sensing unit, A sleepiness score calculation unit calculates a sleepiness score using the sleepiness estimation features calculated by the feature calculation unit, A sleepiness estimation unit estimates the sleepiness of the occupant based on the sleepiness score calculated by the sleepiness score calculation unit, A second noise factor detection unit detects a noise factor driving state, which is a driving state of the moving body that is assumed to be less likely to cause drowsiness in the occupant, based on the moving body information related to the moving body. A third noise factor detection unit detects the occurrence of noise factor sensing, which is an event in which the sensing unit is presumed to have misidentified the sleepiness-related information due to a misdetection of the sleepiness-related state of the occupant, based on the sleepiness-related information acquired by the sensing unit, When the second noise factor detection unit detects the noise factor driving state, or when the third noise factor detection unit detects the occurrence of the noise factor sensing, the system includes a score correction unit that corrects the drowsiness score calculated by the drowsiness score calculation unit based on the noise factor driving state or the occurrence of the noise factor sensing. The drowsiness estimation unit estimates the drowsiness of the occupant based on the corrected drowsiness score after the score correction unit has made corrections. A sleepiness estimation device characterized by the following features.

7. The score correction unit, When the second noise factor detection unit detects the noise factor driving state and the third noise factor detection unit detects the occurrence of the noise factor sensing, the drowsiness score is corrected according to the weights set for the noise factor driving state and the noise factor sensing. The sleepiness estimation device according to claim 6.

8. The feature calculation unit, Based on the noise factor behavior information related to the noise factor behavior detected by the first noise factor detection unit, the sensing unit acquires sleepiness-related information, and the sleepiness-related information that the first noise factor detection unit used to detect the noise factor behavior is excluded from the calculation of the sleepiness estimation feature quantity, and the sensing result selection unit assigns an exclusion flag to such sleepiness-related information. The sensing unit identifies the drowsiness-related information after noise factor removal by excluding the drowsiness-related information to which the sensing result selection unit has assigned the exclusion target flag from the drowsiness-related information acquired by the sensing unit, and calculates the drowsiness estimation feature quantity based on the identified drowsiness-related information after noise factor removal. A sleepiness estimation device according to any one of claims 1, 2, 4, or 6.

9. The feature calculation unit, Based on the noise factor behavior information related to the noise factor behavior detected by the first noise factor detection unit, the sensing result selection unit selects the drowsiness-related information obtained by the sensing unit, after excluding the drowsiness-related information that was the basis for the first noise factor detection unit detecting the noise factor behavior, as the drowsiness-related information after noise factor removal. Based on the drowsiness-related information after noise factor removal selected by the sensing result selection unit, the drowsiness estimation feature quantity is calculated. A sleepiness estimation device according to any one of claims 1, 2, 4, or 6.

10. The occupant of the moving body is the driver of the vehicle. A sleepiness estimation device according to any one of claims 1, 2, 4, or 6.

11. The sensing unit acquires sleepiness-related information for each frame, based on the frame of the captured image of the occupant's face captured by the sensing unit, and the sensing unit acquires sleepiness-related information for each frame, indicating the occupant's state related to sleepiness. The first noise factor detection unit, based on the drowsiness-related information acquired by the sensing unit, detects noise factor behaviors, which are behaviors by the occupant that involve eye movements and are similar to behaviors caused by drowsiness. The process involves a feature calculation unit calculating sleepiness estimation features for estimating the occupant's sleepiness based on the sleepiness-related information obtained by the sensing unit, after the sleepiness-related information that was the basis for the first noise factor detection unit detecting the noise factor behavior has been removed. The drowsiness score calculation unit calculates a drowsiness score using the drowsiness estimation features calculated by the feature calculation unit, The drowsiness estimation unit includes the step of estimating the drowsiness of the occupant based on the drowsiness score calculated by the drowsiness score calculation unit, The aforementioned noise-generating behaviors include downward viewing, The first noise factor detection unit detects that the occupant was looking downwards if, based on the time-series drowsiness-related information, the occupant's gaze direction changes downwards by an angle greater than or equal to the downward-looking determination angle during the downward-looking determination period. A method for estimating drowsiness, characterized by the following features.

12. The sensing unit acquires sleepiness-related information indicating a state related to sleepiness of the occupant, based on the frames of the captured images of the occupant's face captured by the sensing unit, for each frame, The first noise factor detection unit, based on the drowsiness-related information acquired by the sensing unit, detects noise factor behaviors, which are behaviors by the occupant that involve eye movements and are similar to behaviors caused by drowsiness. The process involves a feature calculation unit calculating sleepiness estimation features for estimating the occupant's sleepiness based on the sleepiness-related information obtained by the sensing unit, after the sleepiness-related information that was the basis for the first noise factor detection unit detecting the noise factor behavior has been removed. The drowsiness score calculation unit calculates a drowsiness score using the drowsiness estimation features calculated by the feature calculation unit, The drowsiness estimation unit estimates the drowsiness of the occupant based on the drowsiness score calculated by the drowsiness score calculation unit, The second noise factor detection unit detects a noise factor driving state, which is a driving state of the moving body that is assumed to be less likely to cause drowsiness in the occupant, based on the moving body information related to the moving body. The score correction unit includes a step of correcting the drowsiness score calculated by the drowsiness score calculation unit when the second noise factor detection unit detects the noise factor driving condition. The drowsiness estimation unit, when the score correction unit corrects the drowsiness score calculated by the drowsiness score calculation unit, estimates the drowsiness of the occupant based on the corrected drowsiness score after the score correction unit has corrected it. A method for estimating drowsiness, characterized by the following features.

13. The sensing unit acquires sleepiness-related information indicating a state related to sleepiness of the occupant, based on the frames of the captured images of the occupant's face captured by the sensing unit, for each frame, The first noise factor detection unit, based on the drowsiness-related information acquired by the sensing unit, detects noise factor behaviors, which are behaviors by the occupant that involve eye movements and are similar to behaviors caused by drowsiness. The process involves a feature calculation unit calculating sleepiness estimation features for estimating the occupant's sleepiness based on the sleepiness-related information obtained by the sensing unit, after the sleepiness-related information that was the basis for the first noise factor detection unit detecting the noise factor behavior has been removed. The drowsiness score calculation unit calculates a drowsiness score using the drowsiness estimation features calculated by the feature calculation unit, The drowsiness estimation unit estimates the drowsiness of the occupant based on the drowsiness score calculated by the drowsiness score calculation unit, The third noise factor detection unit detects the occurrence of a noise factor sensing event, which is an event in which the sensing unit is presumed to have misidentified the sleepiness-related information due to the sensing unit misidentifying a sleepiness-related state of the occupant, based on the sleepiness-related information acquired by the sensing unit. The score correction unit includes a step of correcting the drowsiness score calculated by the drowsiness score calculation unit when the third noise factor detection unit detects the occurrence of the noise factor sensing. The sleepiness estimation method is characterized in that, if the score correction unit corrects the sleepiness score calculated by the sleepiness score calculation unit, the sleepiness estimation unit estimates the sleepiness of the occupant based on the corrected sleepiness score after the score correction unit has corrected it.

14. The sensing unit acquires sleepiness-related information indicating a state related to sleepiness of the occupant, based on the frames of the captured images of the occupant's face captured by the sensing unit, for each frame, The first noise factor detection unit, based on the drowsiness-related information acquired by the sensing unit, detects noise factor behaviors, which are behaviors by the occupant that involve eye movements and are similar to behaviors caused by drowsiness. The process involves a feature calculation unit calculating sleepiness estimation features for estimating the occupant's sleepiness based on the sleepiness-related information obtained by the sensing unit, after the sleepiness-related information that was the basis for the first noise factor detection unit detecting the noise factor behavior has been removed. The drowsiness score calculation unit calculates a drowsiness score using the drowsiness estimation features calculated by the feature calculation unit, The drowsiness estimation unit estimates the drowsiness of the occupant based on the drowsiness score calculated by the drowsiness score calculation unit, The second noise factor detection unit detects a noise factor driving state, which is a driving state of the moving body that is assumed to be less likely to cause drowsiness in the occupant, based on the moving body information related to the moving body. The third noise factor detection unit detects the occurrence of a noise factor sensing event, which is an event in which the sensing unit is presumed to have misidentified the sleepiness-related information due to the sensing unit misidentifying a sleepiness-related state of the occupant, based on the sleepiness-related information acquired by the sensing unit. The score correction unit includes a step of correcting the drowsiness score calculated by the drowsiness score calculation unit based on the noise factor driving state or the occurrence of noise factor sensing when the second noise factor detection unit detects the noise factor driving state or the occurrence of noise factor sensing, The drowsiness estimation unit estimates the drowsiness of the occupant based on the corrected drowsiness score after the score correction unit has made corrections. A method for estimating drowsiness, characterized by the following features.

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