Patent Publication Number: US-9904846-B2

Title: Pedestrian behavior predicting device and pedestrian behavior predicting method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a national phase application based on the PCT International Patent Application No. PCT/JP2011/071398 filed on Sep. 20, 2011, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The present invention relates to a pedestrian behavior predicting device and a pedestrian behavior predicting method. 
     BACKGROUND 
     A technique of predicting the behavior of a pedestrian at the periphery of a vehicle has been conventionally developed. 
     For example, a patent literature 1 discloses a pedestrian detecting device for extracting feature points from an image imaged with a camera, calculating movement information including a moving speed and/or moving direction of the extracted feature points, extracting a target region including a moving target three-dimensional object from the imaged image based on the calculated movement information of the feature points, comparing the movement information associated with the extracted target region and the movement information associated with a comparison region set at a periphery of the target region, and determining whether or not the target three-dimensional object included in the extracted target region is a pedestrian based on the comparison result of the movement information. 
     Patent literature 2 discloses a pedestrian rush out predicting device for acquiring time series change of the position and the moving speed and the peripheral information of the pedestrian existing at a front side of the own vehicle, comparing the acquired time series change of the position and the moving speed and the pattern of the time series change of the position and the moving speed of when the pedestrian rushes out to a road, and comparing the acquired peripheral information and the peripheral information obtained in advance for when the pedestrian rushes out to the road to predict whether or not the pedestrian will rush out to the road on which the own vehicle is travelling. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Application Laid-open No. 2009-294842 
     Patent Literature 2: Japanese Patent Application Laid-open No. 2010-102437 
     SUMMARY 
     Technical Problem 
     However, the behavior of the pedestrian at the periphery of the vehicle cannot be rapidly and accurately predicted in the conventional art (the patent literatures 1 and 2, etc.). For example, the pedestrian detecting device described in the patent literature 1 can capture the movement of the pedestrian and predict the linear rush out movement (continuous movement) of the pedestrian that is linearly predictable as the extension of the movement, but cannot predict the movement (discontinuous movement) of suddenly changing direction and rushing out to the road. Furthermore, the pedestrian rush out predicting device described in the patent literature 2 cannot ensure sufficient precision of environmental recognition and thus can still be improved. 
     In light of the foregoing, it is an object of the present invention to provide a pedestrian behavior predicting device and a pedestrian behavior predicting method capable of rapidly and accurately predicting the behavior of the pedestrian at the periphery of the vehicle. 
     Solution to Problem 
     A pedestrian behavior predicting device according to the present invention includes a pedestrian detecting means configured to detect a pedestrian from an imaged image and extract a partial image including the pedestrian; a movement change detecting means configured to detect change in movement of the pedestrian by accumulating shape information of the pedestrian acquired from the partial image extracted by the pedestrian detecting means and comparing the shape information of a predetermined time before and the current shape information using the accumulated shape information; a discontinuous movement estimating means configured to acquire discontinuous movement estimating information indicating a discontinuous movement of the pedestrian that occurs following the change in the movement of the pedestrian from a storage means at the time the change in the movement of the pedestrian is detected by the movement change detecting means; and a behavior predicting means configured to predict a behavior of the pedestrian using the discontinuous movement estimating information acquired by the discontinuous movement estimating means. 
     In the pedestrian behavior predicting device, it is preferable that the movement change detecting means detects the change in the movement of the pedestrian by acquiring a feature amount distribution representing the shape information of the pedestrian acquired from the partial image extracted by the pedestrian detecting means, normalizing the shape information represented by the acquired feature amount distribution, accumulating the normalized shape information, and comparing the shape information of a predetermined time before and the current shape information using the accumulated shape information. 
     In the pedestrian behavior predicting device, it is preferable that the discontinuous movement estimating means calculates an optical flow of the imaged image and acquires the discontinuous movement estimating information using the optical flow at the time the change in the movement of the pedestrian is detected by the movement change detecting means. 
     In the pedestrian behavior predicting device, it is preferable that the pedestrian detecting means acquires a position of the pedestrian on the imaged image, the pedestrian behavior predicting device preferably further includes a continuous movement estimating means configured to generate continuous movement estimating information indicating a continuous movement of the pedestrian that occurs following movement of the position of the pedestrian based on a history of positions of the pedestrian acquired by the pedestrian detecting means, and it is preferable that the behavior predicting means predicts the behavior of the pedestrian based on the continuous movement estimating information generated by the continuous movement estimating means. 
     In the pedestrian behavior predicting device, it is preferable that the discontinuous movement estimating information and the continuous movement estimating information include at least one of a moving direction and a moving speed of the pedestrian. 
     In the pedestrian behavior predicting device, it is preferable that the movement change detecting means further includes a shape information acquiring means configured to acquire the feature amount distribution of the pedestrian from the partial image extracted by the pedestrian detecting means using a predetermined feature amount, a normalizing means configured to normalize the feature amount distribution acquired by the shape information acquiring means and acquire a probability distribution corresponding to the feature amount distribution, a shape information accumulating means configured to accumulate the probability distribution acquired by the normalizing means, and a change detecting means configured to calculate a difference between the probability distribution of a predetermined time before and the current probability distribution accumulated by the shape information accumulating means using a predetermined scale, and detect the change in the movement of the pedestrian at the time the calculated difference is greater than a predetermined threshold value. 
     A pedestrian behavior predicting method according to the present invention includes a pedestrian detecting step configured to detect a pedestrian from an imaged image and extract a partial image including the pedestrian; a movement change detecting step configured to detect change in movement of the pedestrian by accumulating shape information of the pedestrian acquired from the partial image extracted in the pedestrian detecting step, and comparing the shape information of a predetermined time before and the current shape information using the accumulated shape information; a discontinuous movement estimating step configured to acquire discontinuous movement estimating information indicating a discontinuous movement of the pedestrian that occurs following the change in the movement of the pedestrian from a storage means at the time the change in the movement of the pedestrian is detected in the movement change detecting step; and a behavior predicting step configured to predict a behavior of the pedestrian using the discontinuous movement estimating information acquired in the discontinuous movement estimating step. 
     In the movement change detecting step, it is preferable that the change in the movement of the pedestrian is detected by acquiring a feature amount distribution representing the shape information of the pedestrian acquired from the partial image extracted in the pedestrian detecting step, normalizing the shape information represented with the acquired feature amount distribution, accumulating the normalized shape information and comparing the shape information of a predetermined time before and the current shape information. 
     In the discontinuous movement estimating step, it is preferable that an optical flow of the imaged image is calculated, and the discontinuous movement estimating information is acquired using the optical flow at the time the change in the movement of the pedestrian is detected in the movement change detecting step. 
     It is preferable that a position of the pedestrian on the imaged image is acquired in the pedestrian detecting step, the pedestrian behavior predicting method preferably further includes a continuous movement estimating step configured to generate continuous movement estimating information indicating a continuous movement of the pedestrian that occurs following movement of the position of the pedestrian based on a history of positions of the pedestrian acquired in the pedestrian detecting step, and the behavior of the pedestrian is preferably predicted in the behavior predicting step based on the continuous movement estimating information generated in the continuous movement estimating step. 
     Advantageous Effects of Invention 
     The present invention has an effect of rapidly and accurately predicting the behavior of the pedestrian at the periphery of the vehicle. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram illustrating one example of a configuration of the pedestrian behavior predicting device according to the present invention. 
         FIG. 2  is a flowchart illustrating an example of a pedestrian behavior predicting process according to a first embodiment. 
         FIG. 3  is a flowchart illustrating an example of a movement change detecting process according to the first embodiment. 
         FIG. 4  is a view illustrating an example of a movement change detection graph according to the first embodiment. 
         FIG. 5  is a flowchart illustrating one example of a pedestrian behavior predicting process according to a second embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of a pedestrian behavior predicting device and a pedestrian behavior predicting method according to the present invention will be described in detail based on the drawings. It should be noted that the present invention is not to be limited by the embodiments. Furthermore, the configuring elements described in the following embodiments include elements that can be easily contrived by those skilled in the art or elements that are substantially the same. 
     A configuration of a pedestrian behavior predicting device according to the present invention will be described with reference to  FIG. 1 .  FIG. 1  is a block diagram illustrating one example of a configuration of the pedestrian behavior predicting device according to the present invention. 
     As illustrated in  FIG. 1 , a pedestrian behavior predicting device  1  is configured using an automobile control computer, and the like mounted on a vehicle, for example, and is communicably connected to a camera  2  and a notification means  4  mounted on the vehicle. The camera  2  is a device that captures an image of the periphery of the own vehicle and generates image data (imaged image) in which the periphery of the own vehicle is shown. The camera  2  is, for example, an imaging means such as a CCD camera, or a CMOS camera capable of performing imaging in a visible light region or an infrared light region. The camera  2  is installed at an arbitrary position where the periphery of the vehicle such as the front side, the side, and the back side of the vehicle can be imaged. In the present embodiment, the pedestrian behavior predicting device  1  may be simultaneously used with the camera  2 , and a stereo camera, an imaging laser radar, and the like. The notification means  4  is a display that outputs image information, a speaker that outputs audio information, and the like. In the present embodiment, the notification means  4  is used to notify danger to a driver when the pedestrian at the periphery of the vehicle makes a dangerous move while the driver is driving the vehicle. 
     The pedestrian behavior predicting device  1  includes a controller  12  and a storage unit  14 . The controller  12  comprehensively controls the pedestrian behavior predicting device  1 , and is, for example, a CPU (Central Processing Unit), and the like. The storage unit  14  stores data, and is, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk, or the like. 
     The storage unit  14  includes a shape information storage unit  14   a  and a discontinuous movement estimating information storage unit  14   b.    
     The shape information storage unit  14   a  is a shape information storage means that stores shape information of the pedestrian extracted from an imaged image imaged by the camera  2 . The shape information is data indicating a feature amount of the shape of the pedestrian. The feature amount is not limited thereto, and includes at least one of a first feature amount, which uses a luminance itself of the imaged image, a second feature amount, which uses an edge of the imaged image, and a third feature amount, which uses a color of the imaged image. The first feature amount includes, for example, at least one of luminance, PCA of the luminance, Hu moment, LBP, Haarlike feature, and poselet. The second feature amount includes, for example, at least one of SIFT, PCA, SURF, GLOH, shape context, HOG, CoHOG, FIND, and edgelet. The third feature amount includes, for example, at least one of FGB and Lab. 
     The discontinuous movement estimating information storage unit  14   b  is a discontinuous movement estimating information storage means that stores image data at a time point the movement of the pedestrian changed, and discontinuous movement estimating information indicating the discontinuous movement of the pedestrian that occurs following the change in the movement of the pedestrian in correspondence. 
     The change in the movement of the pedestrian means the change in the dangerous movement of the pedestrian at the traffic environment, and includes change in shape at the start of change in the movement of the pedestrian, that is, the change in the feature amount of the image. The change in the movement of the pedestrian is not limited thereto, and includes, for example, sudden direction changing movement of the pedestrian, and sudden arm or leg raising movement of the pedestrian. The discontinuous movement includes, for example, the movement in which the pedestrian suddenly changes the advancing direction from the state of moving along the pavement, the movement in which the pedestrian suddenly moves at high speed from the state of moving at low speed along the pavement, and the movement in which the pedestrian suddenly starts to move from the stopped state. The discontinuous movement estimating information includes at least one of the moving direction or the moving speed of the pedestrian. 
     In the present embodiment, the data stored in the discontinuous movement estimating information storage unit  14   b  is stored in advance by the pedestrian behavior predicting device  1 . Specifically, the pedestrian behavior predicting device  1  corresponds the image data at the time point the change in the movement of the pedestrian is detected to a vector indicating the moving direction and the moving speed representing the discontinuous movement taken by the pedestrian after the change in the movement of the pedestrian, and stores it in the discontinuous movement estimating information storage unit  14   b . For example, if the pedestrian is moving along the pavement on the left side of the road, the pedestrian behavior predicting device  1  corresponds the image data at the time point the sudden direction changing movement toward the right of the pedestrian is detected to the vector indicating, the moving direction and the moving speed representing the movement in which the pedestrian advances toward the road after the sudden direction changing movement toward the right of the pedestrian, and stores it in the discontinuous movement estimating information storage unit  14   b . That is, the discontinuous movement estimating information storage unit  14   b  stores the movement of the pedestrian toward a dangerous direction (right direction in this case) in which the pedestrian suddenly rushes out toward the road side from the pavement in advance as the discontinuous movement estimating information. Furthermore, the pedestrian behavior predicting device  1  corresponds the image data at the time point the sudden direction changing movement toward the left of the pedestrian is detected to the vector indicating the moving direction and the moving speed representing the movement in which the pedestrian moves toward a building after the sudden direction changing movement toward the left of the pedestrian, and stores it in the discontinuous movement estimating information storage unit  14   b . That is, the discontinuous movement estimating information storage unit  14   b  stores the movement of the pedestrian toward a safe direction (left direction in this case) in which the pedestrian suddenly enters the building from the pavement in advance as the discontinuous movement estimating information. Therefore, in the present embodiment, the discontinuous movement estimating information storage unit  14   b  is configured as a knowledge base database that stores data acquired and accumulated beforehand by the pedestrian behavior predicting device  1 . 
     The pedestrian behavior predicting device  1  may update the data stored in the discontinuous movement estimating information storage unit  14   b  by online learning. For example, the pedestrian behavior predicting device  1  may update the data by successively storing the image data for a predetermined time from the time point the change in the movement of the pedestrian is detected, analyzing the image data group, and predicting the discontinuous movement taken by the pedestrian after the change in the movement of the pedestrian. 
     The controller  12  includes a pedestrian detecting unit  12   a , a movement change detecting unit  12   b , a discontinuous movement estimating unit  12   g , a continuous movement estimating unit  12   h , and a behavior predicting unit  12   i . The movement change detecting unit  12   b  further includes a shape information acquiring unit  12   c , a normalizing unit  12   d , a shape information accumulating unit  12   e , and a change detecting unit  12   f.    
     The pedestrian detecting unit  12   a  is a pedestrian detecting means for detecting a pedestrian from an imaged image. The pedestrian detecting unit  12   a  detects the pedestrian by performing pattern matching, and the like using data indicating the outline of the shape of the pedestrian stored in the storage unit  14  in advance. The pedestrian detecting unit  12   a  extracts a partial image including the pedestrian from the imaged image. The pedestrian detecting unit  12   a  also acquires the position of the pedestrian on the imaged image. The position of the pedestrian is preferably a three-dimensional, relative coordinate or an absolute coordinate with respect to the own vehicle. 
     The movement change detecting unit  12   b  is a movement change detecting means for detecting change in the movement of the pedestrian by accumulating the shape information of the pedestrian acquired from the partial image extracted by the pedestrian detecting unit  12   a , and comparing the shape information of a predetermined time before and the current shape information using the accumulated shape information. The movement change detecting unit  12   b  may detect the change in the movement of the pedestrian by acquiring a feature amount distribution representing the shape information of the pedestrian acquired from the partial image extracted by the pedestrian detecting unit  12   a , normalizing the shape information represented with the acquired feature amount distribution, accumulating the normalized shape information, and comparing the shape information of a predetermined time before and the current shape information using the accumulated shape information. The movement change detecting unit  12   b  detects the change in the movement of the pedestrian by the processes of the shape information acquiring unit  12   c , the normalizing unit  12   d , the shape information accumulating unit  12   e , and the change detecting unit  12   f.    
     The shape information acquiring unit  12   c  is a shape information acquiring means for acquiring the shape information of the pedestrian from the partial image extracted by the pedestrian detecting unit  12   a . Specifically, the shape information acquiring unit  12   c  acquires the feature amount distribution representing the shape information of the pedestrian from the partial image extracted by the pedestrian detecting unit  12   a  using a predetermined feature amount. The predetermined feature amount is a feature amount that can be represented as a probability distribution, and includes at least one of the first feature amount, the second feature amount, and the third feature amount described above. 
     The normalizing unit  12   d  is a normalizing means for normalizing the shape information acquired by the shape information acquiring unit  12   c . Specifically, the normalizing unit  12   d  normalizes the feature amount distribution acquired by the shape information acquiring unit  12   c , and acquires a probability distribution corresponding to the relevant feature amount distribution. 
     The shape information accumulating unit  12   e  is a shape information accumulating means for accumulating the shape information normalized by the normalizing unit  12   d . Specifically, the shape information accumulating unit  12   e  accumulates the probability distribution acquired by the normalizing unit  12   d . In other words, the shape information accumulating unit  12   e  stores the normalized shape information (i.e., probability distribution) in the shape information storage unit  14   a . In the present embodiment, the shape information accumulating unit  12   e  may accumulate the feature amount distribution before normalization acquired by the shape information acquiring unit  12   c.    
     The change detecting unit  12   f  is a change detecting means for detecting the change in the movement of the pedestrian by comparing the shape information of a predetermined time before and the current shape information using the normalized shape information accumulated by the shape information accumulating unit  12   e , that is, the normalized shape information stored in the shape information storage unit  14   a . Specifically, the change detecting unit  12   f  calculates the difference between the probability distribution of a predetermined time before and the current probability distribution accumulated in the shape information storage unit  14   a  by the shape information accumulating unit  12   e  using a predetermined scale, and detects the change in the movement of the pedestrian when the calculated difference is greater than a predetermined threshold value. The predetermined scale is a scale for measuring the difference between the probability distributions with a distance or a pseudo-distance. The distance is not limited thereto, and includes Lp norm, for example, L1 norm (Manhattan distance), L2 norm (Euclidean distance), and L infinity norm (uniform norm). The distance may include a Mahalanobis distance. When using the Mahalanobis distance, the distribution is preferably created from a plurality of vectors p(t) of the past. The distance may include a Hamming distance. When using the Hamming distance, the numerical values are preferably discretized to a certain extent. The pseudo-distance is not limited thereto, and includes Kullback-Leibler divergence (hereinafter referred to as KL divergence). The KL divergence is the scale for measuring the distance between two probability distributions P, Q, and is well known in the field of information theory. 
     In the present embodiment, if the feature amount distribution of before normalization is accumulated by the shape information accumulating unit  12   e , the change detecting unit  12   f  may normalize the feature amount distribution of a predetermined time before and the current feature amount distribution stored in the shape information storage unit  14   a , acquire the probability distributions corresponding to each of the feature amount distribution the predetermined time before and the current feature amount distribution, calculate the difference between the acquired probability distribution of the predetermined time before and the current probability distribution using a predetermined scale, and detect the change in the movement of the pedestrian when the calculated difference is greater than a predetermined threshold value. 
     The discontinuous movement estimating unit  12   g  is a discontinuous movement estimating means for acquiring the discontinuous movement estimating information indicating the discontinuous movement of the pedestrian that occurs following the change in the movement of the pedestrian from the discontinuous movement estimating information storage unit  14   b  when the change in the movement of the pedestrian is detected by the movement change detecting unit  12   b . Specifically, when the change in the movement of the pedestrian is detected by the movement change detecting unit  12   b , the discontinuous movement estimating unit  12   g  searches the image data stored in the discontinuous movement estimating information storage unit  14   b  in advance corresponding to the image data at the time point the change in the movement of the pedestrian is detected by pattern matching, and the like. The discontinuous movement estimating unit  12   g  acquires the discontinuous movement estimating information corresponded in advance with the searched image data from the discontinuous movement estimating information storage unit  14   b . The discontinuous movement estimating information includes at least one of the moving direction or the moving speed of the pedestrian. 
     When the change in the movement of the pedestrian is detected by the movement change detecting unit  12   b , the discontinuous movement estimating unit  12   g  may calculate an optical flow of the imaged image and acquire the discontinuous movement estimating information using the optical flow. Specifically, the discontinuous movement estimating unit  12   g  calculates the vector (i.e., optical flow) indicating in which direction the pedestrian on the imaged image is moving based on a correlation of the partial image including the pedestrian and a background image of the periphery of the pedestrian from the temporally successive imaged image. The discontinuous movement estimating unit  12   g  acquires the discontinuous movement estimating information indicating the moving direction and the moving speed of the pedestrian using the calculated optical flow. 
     The continuous movement estimating unit  12   h  is a continuous movement estimating means for generating the continuous movement estimating information indicating the continuous movement of the pedestrian that occurs following the movement of the position of the pedestrian based on a history of positions of the pedestrian acquired by the pedestrian detecting unit  12   a . The continuous movement includes, for example, the movement in which the pedestrian linearly advances at a constant speed from the pavement toward the road. The continuous movement estimating information includes at least one of the moving direction or the moving speed of the pedestrian. The continuous movement estimating unit  12   h  generates the continuous movement estimating information indicating the continuous movement (e.g., movement in which the pedestrian continuously moves, movement in which the pedestrian stops from the moving state, movement in which the pedestrian slows down, and the like) by linear prediction. 
     The behavior predicting unit  12   i  is a behavior predicting means for predicting the behavior of the pedestrian using the discontinuous movement estimating information acquired by the discontinuous movement estimating unit  12   g . For example, when the pedestrian is moving along the pavement on the left side of the road, the behavior predicting unit  12   i  predicts the behavior of the pedestrian using the vector (i.e., discontinuous movement estimating information) indicating the moving direction and the moving speed representing the movement in which the pedestrian proceeds toward the road side after the sudden direction changing movement toward the right of the pedestrian acquired by the discontinuous movement estimating unit  12   g . In this case, the behavior predicting unit  12   i  predicts, as the behavior of the pedestrian, the movement of the pedestrian toward a dangerous direction (right direction in this case) in which the pedestrian suddenly rushes out toward the road side from the pavement. The behavior predicting unit  12   i  predicts the behavior of the pedestrian using the vector (i.e., discontinuous movement estimating information) indicating the moving direction and the moving speed representing the movement in which the pedestrian moves toward the building after the sudden direction changing movement toward the left of the pedestrian acquired by the discontinuous movement estimating unit  12   g . In this case, the behavior predicting unit  12   i  predicts, as the behavior of the pedestrian, the movement of the pedestrian toward a safe direction (left direction in this case) in which the pedestrian suddenly enters the building from the pavement. The behavior predicting unit  12   i  may predict the behavior of the pedestrian based on the continuous movement estimating information generated by the continuous movement estimating unit  12   h . For example, when the pedestrian is linearly moving at a constant speed from the pavement toward the road, the behavior predicting unit  12   i  predicts, as the behavior of the pedestrian, the linear rush out movement of the pedestrian that can be linearly predicted as an extension of the movement. Furthermore, the behavior predicting unit  12   i  may predict, as the behavior of the pedestrian, the pathway indicating when and where the user is at, for example, based on the continuous movement estimating information or the discontinuous movement estimating information. 
     Now, a pedestrian behavior predicting process executed by the pedestrian behavior predicting device  1  described above will be described with reference to  FIG. 2  to  FIG. 5 . Hereinafter, the pedestrian behavior predicting process executed by the pedestrian behavior predicting device  1  according to the present invention will be described in the order of a first embodiment and a second embodiment. In the pedestrian behavior predicting process below, SIFT feature amount will be described by way of example for the feature amount indicating the shape of the pedestrian, but this is not the sole case. The KL divergence will be described by way of example as a scale for measuring the difference between the probability distributions P, Q, but this is not the sole case. 
     [First Embodiment] 
     The pedestrian behavior predicting process according to the first embodiment will be described with reference to  FIG. 2  to  FIG. 4 .  FIG. 2  is a flowchart illustrating an example of a pedestrian behavior predicting process according to the first embodiment.  FIG. 3  is a flowchart illustrating an example of a movement change detecting process according to the first embodiment.  FIG. 4  is a view illustrating an example of a movement change detection graph according to the first embodiment. In the present embodiment, the pedestrian behavior predicting process is assumed to be repeatedly executed while the driver is driving the vehicle. 
     As illustrated in  FIG. 2 , the controller  12  of the pedestrian behavior predicting device  1  first acquires an imaged image, in which the periphery of the own vehicle is shown, from the camera  2  (step SA 1 ). 
     Next, the pedestrian detecting unit  12   a  of the pedestrian behavior predicting device  1  detects the pedestrian from the imaged image acquired in step SA 1  (step SA 2 ). For example, the pedestrian detecting unit  12   a  detects an object by performing pattern matching, and the like using the data indicating the outline of the shape of the pedestrian stored in the storage unit  14  in advance. 
     The controller  12  of the pedestrian behavior predicting device  1  then determines whether or not the pedestrian is detected in step SA 2  (step SA 3 ). The controller  12  proceeds to the processes of the next step SA 4  and step SA 7  when determining that the pedestrian is detected in step SA 3  (step SA 3 : Yes). That is, the controller  12  executes in parallel the processes shown in steps SA 4  to SA 6  and the processes shown in steps SA 7  to SA 11  when determining that the pedestrian is detected in step SA 3 . The controller  12  terminates the pedestrian behavior predicting process as is when determining that the pedestrian is not detected in step SA 3  (step SA 3 : No). 
     The pedestrian detecting unit  12   a  of the pedestrian behavior predicting device  1  then acquires the position of the pedestrian on the imaged image (step SA 4 ) when determining that the pedestrian is detected in step SA 3  (step SA 3 : Yes). The pedestrian detecting unit  12   a  acquires the three-dimensional relative coordinate or the absolute coordinate with respect to the own vehicle for the position of the pedestrian. 
     The continuous movement estimating unit  12   h  of the pedestrian behavior predicting device  1  then generates the continuous movement estimating information indicating the continuous movement of the pedestrian that occurs following the movement of the position of the pedestrian based on a history of positions of the pedestrian acquired by the pedestrian detecting unit  12   a  in step SA 4  (step SA 5 ). The continuous movement includes, for example, the movement in which the pedestrian linearly advances at a constant speed from the pavement toward the road. The continuous movement estimating information includes at least one of the moving direction or the moving speed of the pedestrian. The continuous movement estimating unit  12   h  generates the continuous movement estimating information indicating the continuous movement (e.g., movement in which the pedestrian continuously moves, movement in which the pedestrian stops from the moving state, movement in which the pedestrian slows down, and the like) by linear prediction. 
     The behavior predicting unit  12   i  of the pedestrian behavior predicting device  1  predicts the behavior of the pedestrian using the continuous movement estimating information generated by the continuous movement estimating unit  12   h  in step SA 5  (step SA 6 ). For example, when the pedestrian is linearly moving at a constant speed from the pavement toward the road, the behavior predicting unit  12   i  predicts, as the behavior of the pedestrian, the linear rush out movement of the pedestrian that can be linearly predicted as an extension of the movement. Thereafter, the pedestrian behavior predicting process is terminated. 
     Returning back to step SA 3 , the pedestrian detecting unit  12   a  of the pedestrian behavior predicting device  1  extracts the partial image including the pedestrian from the imaged image (step SA 7 ) when determining that the pedestrian is detected in step SA 3  (step SA 3 : Yes). 
     The movement change detecting unit  12   b  of the pedestrian behavior predicting device  1  then detects the change in the movement of the pedestrian (step SA 8 ) by normalizing the shape information of the pedestrian acquired from the partial image extracted by the pedestrian detecting unit  12   a  in step SA 7 , accumulating the normalized shape information, and comparing the shape information of a predetermined time before and the current shape information using the accumulated shape information. The change in the movement of the pedestrian means the change in the dangerous movement of the pedestrian at the traffic environment, and includes change in shape at the start of change in the movement of the pedestrian, that is, the change in the feature amount of the image. The change in the movement of the pedestrian is not limited thereto, and includes, for example, sudden direction changing movement of the pedestrian, and sudden arm or leg raising movement of the pedestrian. 
     The details of the movement change detecting process executed by the movement change detecting unit  12   b  in step SA 8  will now be described with reference to  FIG. 3  and  FIG. 4 . As will be described below, the movement change detecting unit  12   b  detects the change in the movement of the pedestrian by the processes of the shape information acquiring unit  12   c , the normalizing unit  12   d , the shape information accumulating unit  12   e , and the change detecting unit  12   f.    
     As illustrated in  FIG. 3 , the shape information acquiring unit  12   c  of the pedestrian behavior predicting device  1  acquires the shape information of the pedestrian from the partial image extracted by the pedestrian detecting unit  12   a  in step SA 7  of  FIG. 2  (step SB 1 ). Specifically, the shape information acquiring unit  12   c  carries out the calculation of the SIFT feature amount as the feature amount distribution v(t) representing the shape information of the pedestrian from the partial image extracted by the pedestrian detecting unit  12   a  in step SA 7  of  FIG. 2 . The SIFT feature amount is well known in the field of image recognition, and the like as a feature amount that represents shape. Furthermore, the SIFT feature amount represents, with a histogram, the edge in which direction is distributed in which portion of the imaged image including the object, and thus can be represented as the probability distribution. 
     The normalizing unit  12   d  of the pedestrian behavior predicting device  1  then normalizes the L1 norm of the feature amount distribution v(t) acquired in step SB 1  to 1, and acquires the feature amount (probability distribution) p(t) as illustrated in the following equation (1) (step SB 2 ).
 
Σ i   |p   i ( t )|=1  (1)
 
     The shape information accumulating unit  12   e  of the pedestrian behavior predicting device  1  accumulates the shape information acquired in step SB 2  in the shape information storage unit  14   a  (step SB 3 ). In other words, the shape information accumulating unit  12   e  carries out the accumulation of the feature amount (probability distribution) p(t) normalized in step SB 2 . 
     The change detecting unit  12   f  of the pedestrian behavior predicting device  1  carries out the calculation of the difference d(t, n) between the feature amount of n frames before and the current feature amount from the feature amount (probability distribution) p(t) accumulated in step SB 3  (step SB 4 ). The controller  12  carries out the calculation of the difference d(t, n) using the KL divergence, as illustrated in the following equation (3).
 
 d ( t,n )= D   KL ( p ( t )|| p ( t−n ))  (2)
 
     
       
         
           
             
               
                 
                   
                     
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                   ) 
                 
               
             
           
         
       
     
     The change detecting unit  12   t  of the pedestrian behavior predicting device  1  determines whether or not the difference d(t, n) calculated in step SB 4  is greater than a predetermined threshold value Thre, as illustrated in  FIG. 4  (step SB 5 ). The vertical axis of  FIG. 4  indicates the KL divergence, and the horizontal axis indicates the frame of time. In  FIG. 4 , a state in which the object pedestrian is moving along the pavement is illustrated in frames  54  to  174 , and a state in which the pedestrian suddenly changed the movement is illustrated in frame  180 . 
     The change detecting unit  12   f  of the pedestrian behavior predicting device  1  determines that there is change in the movement of the pedestrian when determining that the difference d(t, n) is greater than the threshold value Thre in step SB 5  (step SB 6 ). Thereafter, the movement change detecting process is terminated. When determining that the difference d(t, n) is smaller than the threshold value Thre in step SB 5  (step SB 5 : No), the change detecting unit  12   f  determines that there is no change in the movement of the pedestrian, and terminates the movement change detecting process as is. That is, the pedestrian behavior predicting device  1  proceeds to the process of step SA 9  of  FIG. 2  after terminating the movement change detecting process illustrated in  FIG. 3 . 
     Returning again back to  FIG. 2 , the pedestrian behavior predicting process according to the first embodiment will be continued. The controller  12  of the pedestrian behavior predicting device  1  determines whether or not the change in the movement of the pedestrian is detected in step SA 8  (step SA 9 ). The controller  12  proceeds to the process of the next step SA 10  when determining that the change in the movement of the pedestrian is detected in step SA 9  (step SA 9 : Yes). The controller  12  terminates the pedestrian behavior predicting process when determining that the change in the movement of the pedestrian is not detected in step SA 9  (step SA 9 : No). 
     When determining that the change in the movement of the pedestrian is detected in step SA 8  (step SA 9 : Yes), the discontinuous movement estimating unit  12   g  of the pedestrian behavior predicting device  1  acquires the discontinuous movement estimating information indicating the discontinuous movement of the pedestrian that occurs following the change in the movement of the pedestrian from the discontinuous movement estimating information storage unit  14   b  (step SA 10 ). The discontinuous movement includes, for example, the movement in which the pedestrian suddenly changes the advancing direction and proceeds toward the road side from the state of moving along the pavement, the movement in which the pedestrian suddenly moves at high speed from the state of moving at low speed along the pavement, and the movement in which the pedestrian suddenly starts to move from the stopped state. The discontinuous movement estimating information includes at least one of the moving direction or the moving speed of the pedestrian. 
     Specifically, in step SA 10 , the discontinuous movement estimating unit  12   g  searches by pattern matching, and the like the image data stored in the discontinuous movement estimating information storage unit  14   b  in advance corresponding to the image data at the time point the change in the movement of the pedestrian is detected when the change in the movement of the pedestrian is detected in step SA 9 . The discontinuous movement estimating unit  12   g  acquires the discontinuous movement estimating information corresponded in advance with the searched image data from the discontinuous movement estimating information storage unit  14   b.    
     The behavior predicting unit  12   i  of the pedestrian behavior predicting device  1  then predicts the behavior of the pedestrian using the discontinuous movement estimating information acquired by the discontinuous movement estimating unit  12   g  in step SA 10  (step SA 11 ). Thereafter, the pedestrian behavior predicting process is terminated. 
     For example, when the pedestrian is moving along the pavement on the left side of the road, the behavior predicting unit  12   i  predicts the behavior of the pedestrian using the vector (i.e., discontinuous movement estimating information) indicating the moving direction and the moving speed representing the movement in which the pedestrian proceeds toward the road side after the sudden direction changing movement toward the right of the pedestrian acquired by the discontinuous movement estimating unit  12   g  in step SA 10 . That is, the behavior predicting unit  12   i  predicts the movement of the pedestrian toward the dangerous direction (right direction in this case) in which the pedestrian suddenly rushes out from the pavement toward the road as the behavior of the pedestrian. The behavior predicting unit  12   i  predicts the behavior of the pedestrian using the vector (i.e., discontinuous movement estimating information) indicating the moving direction and the moving speed representing the movement in which the pedestrian moves toward the building after the sudden direction changing movement toward the left of the pedestrian acquired by the discontinuous movement estimating unit  12   g  in step SA 10 . That is, the behavior predicting unit  12   i  predicts the movement of the pedestrian toward the safe direction (left direction in this case) in which the pedestrian suddenly enters the building from the pavement as the behavior of the pedestrian. Furthermore, the behavior predicting unit  12   i  may predict, as the behavior of the pedestrian, the pathway indicating when and where the user is at, for example, based on the continuous movement estimating information or the discontinuous movement estimating information. Thereafter, the pedestrian behavior predicting process is terminated. 
     The controller  12  of the pedestrian behavior predicting device  1  outputs the image information and/or the audio information that calls the attention on the pedestrian to the driver of the vehicle through the notification means  4  based on the prediction result of the predicted behavior of the pedestrian after terminating the pedestrian behavior predicting process. The controller  12  of the pedestrian behavior predicting device  1  may execute the vehicle control to avoid collision with the pedestrian based on the prediction result of the predicted behavior of the pedestrian. 
     According to the first embodiment, the behavior of the pedestrian at the periphery of the vehicle can be rapidly and accurately predicted than the prior art. For example, the pedestrian detecting device described in the patent literature 1 can capture the movement of the pedestrian and predict the linear rush out movement (continuous movement) of the pedestrian that is linearly predictable as the extension of the movement, but cannot predict the movement (discontinuous movement) of suddenly changing direction and rushing out to the road. According to the first embodiment, even the discontinuous movement can be predicted, and thus the behavior of the pedestrian can be rapidly and accurately predicted than the prior art. Furthermore, the pedestrian rush out predicting device described in the patent literature 2 cannot ensure sufficient precision of environmental recognition and thus can still be improved. According to the first embodiment, the continuous movement is predicted by linear prediction when there is no change in the movement of the pedestrian, and the discontinuous movement is predicted from the shape change of the imaged image when there is change in the movement of the pedestrian, and hence the pedestrian behavior predicting method corresponding to various environments can be applied, and as a result, the behavior of the pedestrian of the periphery of the vehicle can be rapidly and accurately predicted than the prior art. Thus, according to the first embodiment, when the pedestrian at the periphery of the vehicle makes a dangerous move while the driver is driving the vehicle, the danger can be notified to the driver rapidly and accurately so that the possibility of occurrence of traffic accident can be reduced. 
     Furthermore, the pedestrian behavior predicting device  1  according to the first embodiment corresponds the image data at the time point the change in the movement of the pedestrian is detected to the vector indicating the moving direction and the moving speed representing the discontinuous movement taken by the pedestrian after the change in the movement of the pedestrian, and stores it in the discontinuous movement estimating information storage unit  14   b . Thus, according to the first embodiment, consideration can be made even to the direction in which the discontinuous movement after the change in the movement of the pedestrian is detected is performed. As a result, the behavior of the pedestrian can be predicted in a distinguished manner of whether being carried out toward the dangerous direction or whether being carried out toward the safe direction according to the first embodiment. 
     For example, the pedestrian behavior predicting device  1  according to the first embodiment corresponds the image data at the time point the sudden direction changing movement toward the right of the pedestrian is detected to the vector indicating the moving direction and the moving speed representing the movement in which the pedestrian proceeds toward the road side after the sudden direction changing movement toward the right of the pedestrian, and stores it in the discontinuous movement estimating information storage unit  14   b . Thus, for example, when the pedestrian is moving along the pavement on the left side of the road, the movement of the pedestrian toward the dangerous direction (right direction in this case) in which the pedestrian suddenly rushes out toward the road side from the pavement can be predicted as the behavior of the pedestrian based on the discontinuous movement estimating information stored in the discontinuous movement estimating information storage unit  14   b  according to the first embodiment. 
     The pedestrian behavior predicting device  1  according to the first embodiment corresponds the image data at the time point the sudden direction changing movement toward the left of the pedestrian is detected to the vector indicating the moving direction and the moving speed representing the movement in which the pedestrian moves toward the building after the sudden direction changing movement toward the left of the pedestrian, and stores it in the discontinuous movement estimating information storage unit  14   b . Thus, for example, when the pedestrian is moving along the pavement on the left side of the road, the movement of the pedestrian toward the safe direction (left direction in this case) in which the pedestrian suddenly enters the building from the pavement can be predicted as the behavior of the pedestrian based on the discontinuous movement estimating information stored in the discontinuous movement estimating information storage unit  14   b  according to the first embodiment. 
     Thus, according to the first embodiment, when the pedestrian at the periphery of the vehicle makes a dangerous move while the driver is driving the vehicle, the danger can be notified to the driver more rapidly and accurately, so that the possibility of occurrence of traffic accidents can be further reduced. 
     [Second Embodiment] 
     A pedestrian behavior predicting process according to a second embodiment will now be described with reference to  FIG. 5 .  FIG. 5  is a flowchart illustrating one example of the pedestrian behavior predicting process according to the second embodiment. In the present embodiment, the pedestrian behavior predicting process is assumed to be repeatedly executed while the driver is driving the vehicle. 
     As illustrated in  FIG. 5 , the controller  12  of the pedestrian behavior predicting device  1  first acquires the imaged image in which the periphery of the own vehicle is shown from the camera  2  (step SC 1 ). 
     Next, the pedestrian detecting unit  12   a  of the pedestrian behavior predicting device  1  detects the pedestrian from the imaged image acquired in step SC 1  (step SC 2 ). 
     The controller  12  of the pedestrian behavior predicting device  1  then determines whether or not the pedestrian is detected in step SC 2  (step SC 3 ). The controller  12  proceeds to the processes of the next step SC 4  and step SC 7  when determining that the pedestrian is detected in step SC 3  (step SC 3 : Yes). That is, the controller  12  executes in parallel the processes shown in steps SC 4  to SC 6  and the processes shown in steps SC 7  to SC 12  when determining that the pedestrian is detected in step SC 3 . The controller  12  terminates the pedestrian behavior predicting process as is when determining that the pedestrian is not detected in step SC 3  (step SC 3 : No). 
     The pedestrian detecting unit  12   a  of the pedestrian behavior predicting device  1  acquires the position of the pedestrian on the imaged image (step SC 4 ) when determining that the pedestrian is detected in step SC 3  (step SC 3 : Yes). 
     The continuous movement estimating unit  12   h  of the pedestrian behavior predicting device  1  then generates the continuous movement estimating information indicating the continuous movement of the pedestrian that occurs following the movement of the position of the pedestrian based on a history of positions of the pedestrian acquired by the pedestrian detecting unit  12   a  in step SC 4  (step SC 5 ). The continuous movement includes, for example, the movement in which the pedestrian linearly advances at a constant speed from the pavement toward the road. The continuous movement estimating information includes at least one of the moving direction or the moving speed of the pedestrian. 
     The behavior predicting unit  12   i  of the pedestrian behavior predicting device  1  predicts the behavior of the pedestrian using the continuous movement estimating information generated by the continuous movement estimating unit  12   h  in step SC 5  (step SC 6 ). Thereafter, the pedestrian behavior predicting process is terminated. 
     Returning back to step SC 3 , the pedestrian detecting unit  12   a  of the pedestrian behavior predicting device  1  extracts the partial image including the pedestrian from the imaged image (step SC 7 ) when determining that the pedestrian is detected in step SC 3  (step SC 3 : Yes). 
     The movement change detecting unit  12   b  of the pedestrian behavior predicting device  1  detects the change in the movement of the pedestrian based on the partial image extracted by the pedestrian detecting unit  12   a  in step SC 7  (step SC 8 ). The details of the movement change detecting process executed by the movement change detecting unit  12   b  in step SC 8  are similar to  FIG. 3  and  FIG. 4  described above, and thus the description thereof will be omitted. 
     The controller  12  of the pedestrian behavior predicting device  1  then determines whether or not the change in the movement of the pedestrian is detected in step SC 8  (step SC 9 ). The controller  12  proceeds to the process of the next step SC 10  when determining that the change in the movement of the pedestrian is detected in step SC 9  (step SC 9 : Yes). The controller  12  terminates the pedestrian behavior predicting process when determining that the change in the movement of the pedestrian is not detected in step SC 9  (SC 9 : No). 
     The discontinuous movement estimating unit  12   g  of the pedestrian behavior predicting device  1  calculates the optical flow of the imaged image (step SC 10 ) when determining that the change in the movement of the pedestrian is detected in step SC 8  (step SC 9 : Yes). Specifically, the discontinuous movement estimating unit  12   g  calculates the vector (i.e., optical flow) indicating in which direction the pedestrian on the imaged image is moving based on a correlation of the partial image including the pedestrian and a background image of the periphery of the pedestrian from the temporally successive imaged image. 
     The discontinuous movement estimating unit  12   g  of the pedestrian behavior predicting device  1  acquires the discontinuous movement estimating information indicating the discontinuous movement that occurs following the change in the movement of the pedestrian using the optical flow calculated in step SC 10  (step SC 11 ). The discontinuous movement includes, for example, the movement in which the pedestrian suddenly changes the advancing direction and proceeds toward the road side from the state of moving along the pavement, the movement in which the pedestrian suddenly moves at high speed from the state of moving at low speed along the pavement, and the movement in which the pedestrian suddenly starts to move from the stopped state. The discontinuous movement estimating information includes at least one of the moving direction or the moving speed of the pedestrian. 
     The behavior predicting unit  12   i  of the pedestrian behavior predicting device  1  predicts the behavior of the pedestrian using the discontinuous movement estimating information acquired by the discontinuous movement estimating unit  12   g  in step SC 11  (step SC 12 ). Thereafter, the pedestrian behavior predicting process is terminated. 
     The controller  12  of the pedestrian behavior predicting device  1  outputs the image information and/or the audio information that calls the attention on the pedestrian to the driver of the vehicle through the notification means  4  based on the prediction result of the predicted behavior of the pedestrian after terminating the pedestrian behavior predicting process. The controller  12  of the pedestrian behavior predicting device  1  may execute the vehicle control to avoid collision with the pedestrian based on the prediction result of the predicted behavior of the pedestrian. 
     According to the second embodiment, the vector (i.e., discontinuous movement estimating information) indicating the moving direction and the moving speed representing the discontinuous movement taken by the pedestrian after the change in the movement of the pedestrian can be acquired using the optical flow calculated from the imaged image. Thus, according to the second embodiment, consideration can also be made on the direction of the discontinuous movement of after the change in the movement of the pedestrian is detected, similar to the first embodiment described above, even if the discontinuous movement estimating information is not stored in the storage means in advance. As a result, according to the second embodiment, the behavior of the pedestrian can be predicted in a distinguished manner of whether being carried out toward the dangerous direction or whether being carried out toward the safe direction. Therefore, according to the second embodiment, when the pedestrian at the periphery of the vehicle makes a dangerous move while the driver is driving the vehicle, the danger can be notified to the driver more rapidly and accurately, and thus the possibility of occurrence of traffic accidents can be further reduced, similar to the first embodiment described above. 
     REFERENCE SIGNS LIST 
       1  pedestrian behavior predicting device 
       12  controller 
       12   a  pedestrian detecting unit 
       12   b  movement change detecting unit 
       12   c  shape information acquiring unit 
       12   d  normalizing unit 
       12   e  shape information accumulating unit 
       12   f  change detecting unit 
       12   g  discontinuous movement estimating unit 
       12   h  continuous movement estimating unit 
       12   i  behavior predicting unit 
       14  storage unit 
       14   a  shape information storage unit 
       14   b  discontinuous movement estimating information storage unit 
       2  camera 
       4  notification means