Patent Publication Number: US-11036218-B2

Title: Interaction apparatus, interaction method, recording medium storing interaction program, and robot

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an apparatus, a method, a recording medium storing a program, and a robot for interacting with a user while two-dimensionally moving through a predetermined space. 
     2. Description of the Related Art 
     There is a variety of conceivable situations in which a robot and a human, particularly a young child, have communication with each other. Examples of conceivable situations include a situation where the robot and the young child have a conversation with each other using language, a situation where the robot questions the young child and the young child answers, a situation where the robot and the young child assume their respective roles and play a game that entails actions, and similar situations. 
     In a case where the robot and the young child play a game such as hide-and-seek or tag, the robot needs to have a capability of winning a victory over the young child. As an example, in the case of hide-and-seek where the robot assumes the role of a seeker and the young child assumes the role of a hider, the young child can hide in a room of a house where there are a large number of places that become the robot&#39;s blind spots. Examples of places that become the robot&#39;s blind spots in which the young child can hide include a space between a door that is open and a wall, a space that is formed by the young child wrapping him/herself in a curtain, a space that is formed by the young child wrapping him/herself in a blanket on a sofa, and similar spaces. 
     In order to find the young child hiding in such a space that becomes a blind spot, the robot needs to recognize, as a blind spot, the space in which the young child is hiding and narrow down to the space in which the young child is hiding. For example, Japanese Patent No. 5407898 discloses a technology for checking how a blind spot exists in a space. 
     SUMMARY 
     However, the conventional technology has needed further improvement, as it has difficulty in identifying the position of a blind spot in which a user is hiding, although it can identify the position of a blind spot in a space. 
     One non-limiting and exemplary embodiment provides an apparatus, a method, a recording medium storing a program, and a robot that make it possible to identify a blind spot in which a user is highly likely to be hiding and that cannot be seen from the apparatus. 
     In one general aspect, the techniques disclosed here feature an apparatus for interacting with a user while two-dimensionally moving through a predetermined space, including: a movement mechanism; a sensor that detects an electromagnetic wave or sound wave reflected by an object; a microphone that acquires a sound of an area around the apparatus; a speaker; a processor; and a memory, wherein in a case where the processor has determined that the sound thus acquired contains a first speech to an effect that the user starts hide-and-seek with the apparatus, the processor selects, with reference to a first table stored in the memory, a first region where the number of blind spots is smallest in the space, the first table associating a plurality of regions included in the space and the numbers of blind spots in the plurality of regions with each other, the processor controls the movement mechanism to cause the apparatus to move to the first region, the processor causes the speaker to output a first sound, the processor counts a predetermined number, when counting the predetermined number, the processor causes the sensor to trace a movement locus of the user, in a case where the processor has finished counting the predetermined number, the processor causes the speaker to output a sound indicating that the processor has finished counting the predetermined number, in a case where the processor has determined that the sound thus acquired contains a second speech indicating that the user has finished hiding, the processor controls the movement mechanism to cause the apparatus to move through an entire region in the space through which the apparatus is able to move, in a case where the sensor has not detected the user by a time the apparatus finishes moving through the entire region, the processor selects, with reference to a second table stored in the memory, a first blind spot falling within a predetermined range from an end of the movement locus, the second table associating a blind spot in the space and a position of the blind spot with each other, the processor determines whether the apparatus intentionally loses in hide-and-seek, in a case where the processor has determined that the apparatus does not intentionally lose, the processor controls the movement mechanism to cause the apparatus to move to the first blind spot, the processor causes the speaker to output a second sound, in a case where the processor has determined that the sound thus acquired contains a third speech indicating an admission of defeat in hide-and-seek by the user, the processor causes the speaker to output a third sound, and in a case where the processor has determined that the sound thus acquired does not contain the third speech, the processor causes the speaker to output a fourth sound. 
     These general and specific aspects may be implemented using a computer program, and any combination of systems, methods, and computer programs. 
     The present disclosure makes it possible to identify a blind spot in which the user is highly likely to be hiding and that cannot be seen from the apparatus. 
     It should be noted that general or specific embodiments may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any selective combination thereof. 
     Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. The benefits and/or advantages may be individually obtained by the various embodiments and features of the specification and drawings, which need not all be provided in order to obtain one or more of such benefits and/or advantages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an example of a layout of a room where a robot and a young child play a game; 
         FIG. 2  is an external perspective view of a robot according to an embodiment of the present disclosure; 
         FIG. 3  is an internal perspective view of the robot according to the embodiment of the present disclosure; 
         FIG. 4  is a block diagram showing an example of a configuration of the robot according to the embodiment of the present disclosure; 
         FIG. 5  is a diagram showing an example of an object position information table according to the present embodiment; 
         FIG. 6  is a diagram showing an example of a blind spot target object table according to the present embodiment; 
         FIG. 7  is a diagram showing an example of a blind spot map table according to the present embodiment; 
         FIG. 8  is a diagram for explaining a visual field of the robot according to the present embodiment; 
         FIG. 9  is a diagram showing examples of a plurality of regions divided according to the number of blind spots according to the present embodiment; 
         FIG. 10  is a diagram showing an example of a number-of-blind-spots table according to the present embodiment; 
         FIG. 11  is a diagram showing an example of an intention interpretation table according to the present embodiment; 
         FIG. 12  is a flow chart showing an example of a process for creating the object position information table on the basis of data of an object recognition sensor according to the present embodiment; 
         FIG. 13  is a flow chart showing an example of a process for creating the blind spot map table on the basis of data of the object position information table according to the present embodiment; 
         FIG. 14  is a flow chart showing an example of a process for creating and updating the number-of-blind-spots table on the basis of data of the blind spot map table according to the present embodiment; 
         FIG. 15  is a first flow chart for explaining an example of a process by which the robot and a young child play hide-and-seek according to the present embodiment; 
         FIG. 16  is a second flow chart for explaining the example of the process by which the robot and the young child play hide-and-seek according to the present embodiment; 
         FIG. 17  is a third flow chart for explaining the example of the process by which the robot and the young child play hide-and-seek according to the present embodiment; 
         FIG. 18  is a diagram showing examples of speech text patterns that are outputted from a speaker according to the present embodiment; and 
         FIG. 19  is a diagram showing examples of expression patterns that are displayed on a display according to the present embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Underlying Knowledge Forming Basis of the Present Disclosure 
     In a case where a robot including a movement mechanism and a human, particularly a young child under 6, have communication with each other, it is conceivable that they may play a variety of games. Examples of games include a game in which the robot finds the young child hiding somewhere in a house. At a game starting sign from the young child, the game is started between the young child and the robot. The young child hides in a place in a room of the house where it is hard to find him/her. After a designated period of time such as 30 seconds or 1 minute has elapsed, the robot starts to seek for the hiding young child. In a case where the robot has successfully found the young child by identifying the place in which the young child is hiding, the robot is a winner. Further, in a case where the robot has failed to identify the place in which the young child is hiding or a case where the robot has erroneously identified the place in which the young child is hiding, the hiding young child is a winner. 
       FIG. 1  is a diagram showing an example of a layout of a room where the robot and the young child play a game. In a case where the game is played more than once, it is conceivable that the robot may 100% lose to the young child. As illustrated in  FIG. 1 , a room of a house has places that make the young child&#39;s body invisible from the robot&#39;s sight, such as a gap  1001  that is formed between a door that is open and a wall, a sofa  1002  on which the young child can hide by covering him/herself with a blanket, a closet  1003  in which the young child can hide by closing its door, and a curtain  1004  behind which the young child can hide by changing its shape. 
     In order to win in a case where the young child hides in such a place that becomes the robot&#39;s blind spot, the robot needs to grasp in advance blind-spot regions that do not come into sight even when the robot seeks in the room for the young child. A blind spot in the room can be identified by using the technology of Japanese Patent No. 5407898. 
     However, even if the robot can identify, using the technology of Japanese Patent No. 5407898, a plurality of blind-spot regions in the room that become blind spots when seen from the present position, it is difficult to narrow down which of the plurality of blind-spot regions the young child is hiding in. Even if the robot includes a movement mechanism and is able to move through every place in the room excluding obstacles, the robot needs to include a door opening and closing mechanism, a curtain opening and closing mechanism, or a blanket pulling mechanism in order to identify, from among such a space formed between the door that is open and the wall, such a space formed by the young child wrapping him/herself in the curtain, and such a space formed by the young child wrapping him/herself in the blanket on the sofa, the space in which the young child is hiding. 
     However, a robot not including a door opening and closing mechanism, a curtain opening and closing mechanism, or a blanket pulling mechanism is undesirably unable to reach the space formed between the door that is open and the wall, the space formed by the young child wrapping him/herself in the curtain, and the space formed by the young child wrapping him/herself in the blanket on the sofa. 
     Further, in a case where a plurality of blind-spot regions are present at the start of the game, the blind spot in which the young child cannot be identified from among the plurality of blind spots. Although the robot can randomly select one blind spot from among the plurality of blind spots, the young child may not be hiding in the blind spot randomly selected, and a technology for identifying, from among the plurality of blind spots, the blind spot in which the young child is hiding has not been heretofore studied. 
     In one general aspect, the techniques disclosed here feature an apparatus for interacting with a user while two-dimensionally moving through a predetermined space, including: a movement mechanism; a sensor that detects an electromagnetic wave or sound wave reflected by an object; a microphone that acquires a sound of an area around the apparatus; a speaker; a processor; and a memory, wherein in a case where the processor has determined that the sound thus acquired contains a first speech to an effect that the user starts hide-and-seek with the apparatus, the processor selects, with reference to a first table stored in the memory, a first region where the number of blind spots is smallest in the space, the first table associating a plurality of regions included in the space and the numbers of blind spots in the plurality of regions with each other, the processor controls the movement mechanism to cause the apparatus to move to the first region, the processor causes the speaker to output a first sound, the processor counts a predetermined number, when counting the predetermined number, the processor causes the sensor to trace a movement locus of the user, in a case where the processor has finished counting the predetermined number, the processor causes the speaker to output a sound indicating that the processor has finished counting the predetermined number, in a case where the processor has determined that the sound thus acquired contains a second speech indicating that the user has finished hiding, the processor controls the movement mechanism to cause the apparatus to move through an entire region in the space through which the apparatus is able to move, in a case where the sensor has not detected the user by a time the apparatus finishes moving through the entire region, the processor selects, with reference to a second table stored in the memory, a first blind spot falling within a predetermined range from an end of the movement locus, the second table associating a blind spot in the space and a position of the blind spot with each other, the processor determines whether the apparatus intentionally loses in hide-and-seek, in a case where the processor has determined that the apparatus does not intentionally lose, the processor controls the movement mechanism to cause the apparatus to move to the first blind spot, the processor causes the speaker to output a second sound, in a case where the processor has determined that the sound thus acquired contains a third speech indicating an admission of defeat in hide-and-seek by the user, the processor causes the speaker to output a third sound, and in a case where the processor has determined that the sound thus acquired does not contain the third speech, the processor causes the speaker to output a fourth sound. 
     According to this configuration, in a case where the processor has determined that the sound thus acquired contains a first speech to the effect that the user starts hide-and-seek with the apparatus, the processor selects, with reference to a first table stored in the memory, a first region where the number of blind spots is smallest in the space. The first table associates a plurality of regions included in the space and the numbers of blind spots in the plurality of regions with each other. The processor controls the movement mechanism to cause the apparatus to move to the first region. The processor causes the speaker to output a first sound. The processor counts a predetermined number. When counting the predetermined number, the processor causes the sensor to trace a movement locus of the user. In a case where the processor has finished counting the predetermined number, the processor causes the speaker to output a sound indicating that the processor has finished counting the predetermined number. In a case where the processor has determined that the sound thus acquired contains a second speech indicating that the user has finished hiding, the processor controls the movement mechanism to cause the apparatus to move through an entire region in the space through which the apparatus is able to move. In a case where the sensor has not detected the user by the time the apparatus finishes moving through the entire region, the processor selects, with reference to a second table stored in the memory, a first blind spot falling within a predetermined range from an end of the movement locus. The second table associates a blind spot in the space and a position of the blind spot with each other. The processor determines whether the apparatus intentionally loses in hide-and-seek. In a case where the processor has determined that the apparatus does not intentionally lose, the processor controls the movement mechanism to cause the apparatus to move to the first blind spot. The processor causes the speaker to output a second sound. In a case where the processor has determined that the sound thus acquired contains a third speech indicating an admission of defeat in hide-and-seek by the user, the processor causes the speaker to output a third sound. In a case where the processor has determined that the sound thus acquired does not contain the third speech, the processor causes the speaker to output a fourth sound. 
     Accordingly, after the movement locus of the user has been traced by the sensor when the predetermined number has been counted and the user is hiding in the first region where the number of blind spots is smallest in the space, a movement to the entire region through which the apparatus is able to move is started, and in a case where the sensor has not detected the user by the time the apparatus finishes moving through the entire region, the first blind spot falling within the predetermined range from the end of the movement locus of the user is selected and the apparatus is moved to the first blind spot. Note here that the first blind spot can be said to be a blind spot in which the user is highly likely to have hidden, as the first blind spot falls within the predetermined range from the end of the movement locus of the user. This makes it possible to identify a blind spot in which the user is highly likely to be hiding and that cannot been seen from the apparatus. 
     Further, the apparatus may be configured such that in a case where the processor has determined that the apparatus intentionally loses, the processor selects, with reference to the second table, a second blind spot falling outside the predetermined range, the processor controls the movement mechanism to cause the apparatus to move to the second blind spot, the processor causes the speaker to output the second sound, in a case where the processor has determined that the sound thus acquired contains the third speech, the processor causes the speaker to output the third sound, and in a case where the processor has determined that the sound thus acquired does not contain the third speech, the processor causes the speaker to output the fourth sound. 
     According to this configuration, in a case where the processor has determined that the apparatus intentionally loses, the processor selects, with reference to the second table, a second blind spot falling outside the predetermined range. The processor controls the movement mechanism to cause the apparatus to move to the second blind spot, and the processor causes the speaker to output the second sound. In a case where the processor has determined that the sound thus acquired contains the third speech, the processor causes the speaker to output the third sound. In a case where the processor has determined that the sound thus acquired does not contain the third speech, the processor causes the speaker to output the fourth sound. 
     Accordingly, in a case where the processor has determined that the apparatus intentionally loses, the processor selects the second blind spot falling outside the end of the movement locus of the user. This makes it possible to prevent the apparatus from always keeping winning a victory over the user in hide-and-seek. 
     Further, the apparatus may be configured such that the sensor includes at least one of a camera, an infrared sensor, an ultrasonic sensor, and a laser sensor. 
     According to this configuration, the sensor includes at least one of a camera, an infrared sensor, an ultrasonic sensor, and a laser sensor. This makes it possible to accurately recognize the position of an object that constitutes a blind spot in the predetermined space. 
     Further, the apparatus may be configured such that in a case where the processor has determined that the sound thus acquired does not contain the third speech and where the sensor has detected the user hiding in a third blind spot that is not included in the second table, the processor stores the third blind spot and a position of the third blind spot in the second table in association with each other. 
     According to this configuration, in a case where the processor has determined that the sound thus acquired does not contain the third speech and where the sensor has detected the user hiding in a third blind spot that is not included in the second table, the processor stores the third blind spot and a position of the third blind spot in the second table in association with each other. 
     Accordingly, in a case where a position in which the user was hiding has not been stored in the second table, the third blind spot in which the user was hiding and the position of the third blind spot are stored in the second table in association with each other. This makes it possible to improve the precision with which to identify the blind spot in which the user is hiding. 
     Further, the apparatus may be configured such that in a case where the sensor has detected the user by the time the apparatus finishes moving through the entire region, the processor causes the speaker to output the third sound. 
     According to this configuration, in a case where the sensor has detected the user by the time the apparatus finishes moving through the entire region, the processor causes the speaker to output the third sound. This makes it possible to detect the user in a case where the user is in a place that does not become a blind spot. 
     Further, the apparatus may be configured such that in causing the first sound to be outputted, the processor causes the display to display a first display corresponding to the first sound, that in causing the second sound to be outputted, the processor causes the display to display a second display corresponding to the second sound, that in causing the third sound to be outputted, the processor causes the display to display a third display corresponding to the third sound, and that in causing the fourth sound to be outputted, the processor causes the display to display a fourth display corresponding to the fourth sound. 
     According to this configuration, in causing the first sound to be outputted, the processor causes the display to display a first display corresponding to the first sound. Further, in causing the second sound to be outputted, the processor causes the display to display a second display corresponding to the second sound. Further, in causing the third sound to be outputted, the processor causes the display to display a third display corresponding to the third sound. Further, in causing the fourth sound to be outputted, the processor causes the display to display a fourth display corresponding to the fourth sound. 
     Accordingly, in addition to a sound, a display corresponding to the sound is displayed on the display. This allows the user to grasp the current situation not only through hearing but also through sight. 
     Further, the apparatus may be configured such that the display displays a facial expression of the apparatus with both eyes and a mouth, that the first sound indicates a start of hide-and-seek, and that the first display indicates a smile. 
     According to this configuration, after the apparatus has moved to the first region, the first sound indicating the start of hide-and-seek is outputted and the first display indicating a simile is displayed with both eyes and the mouth. This makes it possible to notify the user of the start of hide-and-seek. 
     Further, the apparatus may be configured such that the display displays a facial expression of the apparatus with both eyes and a mouth, that the second sound indicates that the apparatus has found the user, and that the second display indicates a smile. 
     According to this configuration, after the apparatus has moved to the first region, the second sound indicating that the apparatus has found the user is outputted and the second display indicating a simile is displayed with both eyes and the mouth. This makes it possible to determine the outcome of hide-and-seek by encouraging the user hiding in the blind spot to come out of the blind spot. 
     Further, the apparatus may be configured such that the display displays a facial expression of the apparatus with both eyes and a mouth, that the third sound indicates that the apparatus has won a victory over the user in hide-and-seek, and that the third display indicates a smile. 
     According to this configuration, in a case where the processor has determined that the sound thus acquired contains a third speech indicating an admission of defeat in hide-and-seek by the user, the third sound indicating the apparatus has won a victory over the user in hide-and-seek and the third display indicating a smile is displayed with both eyes and the mouth. This makes it possible to notify that user that the apparatus has won a victory over the user in hide-and-seek. 
     Further, the apparatus may be configured such that the display displays a facial expression of the apparatus with both eyes and a mouth, that the fourth sound indicates that the apparatus has lost to the user in hide-and-seek, and that the fourth display indicates a facial expression of sorrow. 
     According to this configuration, in a case where the processor has determined that the sound thus acquired does not contains a third speech indicating an admission of defeat in hide-and-seek by the user, the fourth sound indicating the apparatus has lost to the user in hide-and-seek and the fourth display indicating a facial expression of sorrow is displayed with both eyes and the mouth. This makes it possible to notify that user that the apparatus has lost to the user in hide-and-seek. 
     A robot according to another aspect of the present disclosure includes: a main housing that is a sphere from which a first side part and a second side part opposite to the first side part have been cut; a first spherical crown corresponding to the first side part; and a second spherical crown corresponding to the second side part, and the foregoing apparatus being a robot. This configuration makes it possible to apply the foregoing apparatus to a robot. 
     A method according to another aspect of the present disclosure is a method by which an apparatus interacts with a user while two-dimensionally moving through a predetermined space, including: in a case where the apparatus has determined that a sound acquired by a microphone contains a first speech to an effect that the user starts hide-and-seek with the apparatus, selecting, with reference to a first table stored in the memory, a first region where the number of blind spots is smallest in the space, the first table associating a plurality of regions included in the space and the numbers of blind spots in the plurality of regions with each other; controlling a movement mechanism to cause the apparatus to move to the first region; causing the speaker to output a first sound; counting a predetermined number; when counting the predetermined number, causing a sensor that detects an electromagnetic wave or sound wave reflected by an object to trace a movement locus of the user; in a case where the apparatus has finished counting the predetermined number, causing the speaker to output a sound indicating that the apparatus has finished counting the predetermined number; in a case where the apparatus has determined that the sound acquired by the microphone contains a second speech indicating that the user has finished hiding, controlling the movement mechanism to cause the apparatus to move through an entire region in the space through which the apparatus is able to move; in a case where the sensor has not detected the user by a time the apparatus finishes moving through the entire region, selecting, with reference to a second table stored in the memory, a first blind spot falling within a predetermined range from an end of the movement locus, the second table associating a blind spot in the space and a position of the blind spot with each other; determining whether the apparatus intentionally loses in hide-and-seek; in a case where the apparatus has determined that the apparatus does not intentionally lose, controlling the movement mechanism to cause the apparatus to move to the first blind spot; causing the speaker to output a second sound; in a case where the apparatus has determined that the sound acquired by the microphone contains a third speech indicating an admission of defeat in hide-and-seek by the user, causing the speaker to output a third sound; and in a case where the apparatus has determined that the sound acquired by the microphone does not contain the third speech, causing the speaker to output a fourth sound. 
     According to this configuration, in a case where the apparatus has determined that a sound acquired by a microphone contains a first speech to the effect that the user starts hide-and-seek with the apparatus, the apparatus selects, with reference to a first table stored in the memory, a first region where the number of blind spots is smallest in the space. The first table associates a plurality of regions included in the space and the numbers of blind spots in the plurality of regions with each other. The apparatus controls a movement mechanism to cause the apparatus to move to the first region. The apparatus causes the speaker to output a first sound. The apparatus counts a predetermined number. When counting the predetermined number, the apparatus causes a sensor that detects an electromagnetic wave or sound wave reflected by an object to trace a movement locus of the user. In a case where the apparatus has finished counting the predetermined number, the apparatus causes the speaker to output a sound indicating that the apparatus has finished counting the predetermined number. In a case where the apparatus has determined that the sound acquired by the microphone contains a second speech indicating that the user has finished hiding, the apparatus controls the movement mechanism to cause the apparatus to move through an entire region in the space through which the apparatus is able to move. In a case where the sensor has not detected the user by the time the apparatus finishes moving through the entire region, the apparatus selects, with reference to a second table stored in the memory, a first blind spot falling within a predetermined range from an end of the movement locus. The second table associates a blind spot in the space and a position of the blind spot with each other. The apparatus determines whether the apparatus intentionally loses in hide-and-seek. In a case where the apparatus has determined that the apparatus does not intentionally lose, the apparatus controls the movement mechanism to cause the apparatus to move to the first blind spot. The apparatus causes the speaker to output a second sound. In a case where the apparatus has determined that the sound acquired by the microphone contains a third speech indicating an admission of defeat in hide-and-seek by the user, the apparatus causes the speaker to output a third sound. In a case where the apparatus has determined that the sound acquired by the microphone does not contain the third speech, the apparatus causes the speaker to output a fourth sound. 
     Accordingly, after the movement locus of the user has been traced by the sensor when the predetermined number has been counted and the user is hiding in the first region where the number of blind spots is smallest in the space, a movement to the entire region through which the apparatus is able to move is started, and in a case where the sensor has not detected the user by the time the apparatus finishes moving through the entire region, the first blind spot falling within the predetermined range from the end of the movement locus of the user is selected and the apparatus is moved to the first blind spot. Note here that the first blind spot can be said to be a blind spot in which the user is highly likely to have hidden, as the first blind spot falls within the predetermined range from the end of the movement locus of the user. This makes it possible to identify a blind spot in which the user is highly likely to be hiding and that cannot been seen from the apparatus. 
     A non-transitory computer-readable recording medium storing a program according to another aspect of the present disclosure is a non-transitory computer-readable recording medium storing a program for interacting with a user while two-dimensionally moving through a predetermined space, the program causing a processor of an apparatus for interacting with the user to execute a process including: in a case where the processor has determined that a sound acquired by a microphone contains a first speech to an effect that the user starts hide-and-seek with the apparatus, selecting, with reference to a first table stored in the memory, a first region where the number of blind spots is smallest in the space, the first table associating a plurality of regions included in the space and the numbers of blind spots in the plurality of regions with each other; controlling a movement mechanism to cause the apparatus to move to the first region; causing the speaker to output a first sound; counting a predetermined number; when counting the predetermined number, causing a sensor that detects an electromagnetic wave or sound wave reflected by an object to trace a movement locus of the user; in a case where the processor has finished counting the predetermined number, causing the speaker to output a sound indicating that the apparatus has finished counting the predetermined number; in a case where the processor has determined that the sound acquired by the microphone contains a second speech indicating that the user has finished hiding, controlling the movement mechanism to cause the apparatus to move through an entire region in the space through which the apparatus is able to move; in a case where the sensor has not detected the user by a time the apparatus finishes moving through the entire region, selecting, with reference to a second table stored in the memory, a first blind spot falling within a predetermined range from an end of the movement locus, the second table associating a blind spot in the space and a position of the blind spot with each other; determining whether the apparatus intentionally loses in hide-and-seek; in a case where the processor has determined that the apparatus does not intentionally lose, controlling the movement mechanism to cause the apparatus to move to the first blind spot; causing the speaker to output a second sound; in a case where the processor has determined that the sound acquired by the microphone contains a third speech indicating an admission of defeat in hide-and-seek by the user, causing the speaker to output a third sound; and in a case where the processor has determined that the sound acquired by the microphone does not contain the third speech, causing the speaker to output a fourth sound. 
     In a case where the processor has determined that a sound acquired by a microphone contains a first speech to the effect that the user starts hide-and-seek with the apparatus, the processor selects, with reference to a first table stored in the memory, a first region where the number of blind spots is smallest in the space. The first table associates a plurality of regions included in the space and the numbers of blind spots in the plurality of regions with each other. The processor controls a movement mechanism to cause the apparatus to move to the first region. The processor causes the speaker to output a first sound. The processor counts a predetermined number. When counting the predetermined number, the processor causes a sensor that detects an electromagnetic wave or sound wave reflected by an object to trace a movement locus of the user. In a case where the processor has finished counting the predetermined number, the processor causes the speaker to output a sound indicating that the apparatus has finished counting the predetermined number. In a case where the processor has determined that the sound acquired by the microphone contains a second speech indicating that the user has finished hiding, the processor controls the movement mechanism to cause the apparatus to move through an entire region in the space through which the apparatus is able to move. In a case where the sensor has not detected the user by the time the apparatus finishes moving through the entire region, the processor selects, with reference to a second table stored in the memory, a first blind spot falling within a predetermined range from an end of the movement locus. The second table associates a blind spot in the space and a position of the blind spot with each other. The apparatus determines whether the apparatus intentionally loses in hide-and-seek. In a case where the processor has determined that the apparatus does not intentionally lose, the apparatus controls the movement mechanism to cause the apparatus to move to the first blind spot. The apparatus causes the speaker to output a second sound. In a case where the processor has determined that the sound acquired by the microphone contains a third speech indicating an admission of defeat in hide-and-seek by the user, the apparatus causes the speaker to output a third sound. In a case where the processor has determined that the sound acquired by the microphone does not contain the third speech, the apparatus causes the speaker to output a fourth sound. 
     Accordingly, after the movement locus of the user has been traced by the sensor when the predetermined number has been counted and the user is hiding in the first region where the number of blind spots is smallest in the space, a movement to the entire region through which the apparatus is able to move is started, and in a case where the sensor has not detected the user by the time the apparatus finishes moving through the entire region, the first blind spot falling within the predetermined range from the end of the movement locus of the user is selected and the apparatus is moved to the first blind spot. Note here that the first blind spot can be said to be a blind spot in which the user is highly likely to have hidden, as the first blind spot falls within the predetermined range from the end of the movement locus of the user. This makes it possible to identify a blind spot in which the user is highly likely to be hiding and that cannot been seen from the apparatus. 
     An embodiment for carrying out the present disclosure is described below with reference to the drawings. Identical signs refer to identical objects throughout all of the following drawings unless otherwise noted. It should be noted that each of the embodiments to be described below shows an example of the present disclosure. The numerical values, shapes, constituent elements, steps, and orders of steps that are shown in the following embodiments are mere examples and are not intended to limit the present disclosure. Further, those of the constituent elements according to the following embodiments which are not recited in an independent claim representing the most generic concept are described as optional constituent elements. Further, the contents of each of the embodiments may be combined with the contents of the other embodiment. 
     Embodiment 
       FIG. 2  is an external perspective view of a robot  100 , which is an example of an interaction apparatus  200 , according to an embodiment of the present disclosure, and  FIG. 3  is an internal perspective view of the robot  100 , which is an example of the interaction apparatus  200 , according to the embodiment of the present disclosure. 
     As shown in  FIG. 2 , the robot  100  (interaction apparatus  200 ) includes a main housing  201  that is spherical, a first spherical crown  202 , and a second spherical crown  203 . The main housing  201 , the first spherical crown  202 , and the second spherical crown  203  constitute a sphere as a whole. That is, the robot  100  has a spherical shape. The robot  100  interacts with a user while two-dimensionally moving through a predetermined space. The first spherical crown  202  and the second spherical crown  203  is coupled to each other by a shaft (not illustrated) provided in the main housing  201 . Meanwhile, the shaft and the main housing  201  are not fixed to each other. Accordingly, rotating the shaft causes the first spherical crown  202  and the second spherical crown  203  to rotate, allowing the robot  100  to move forward or move backward. 
     Further, as shown in  FIG. 2 , the robot  100  includes a speaker  118  in the main housing  201 , and includes a camera  204  and a microphone  109  in the first spherical crown  202 . The speaker  118  outputs a sound of the robot  100 . The camera  204  acquires a picture of an environment surrounding the robot  100 . The microphone  109  acquires a sound of the environment surrounding the robot  100 . In the present aspect, the robot  100  includes the speaker  118  in the main housing  201 . However, this does not imply any limitation. The robot  100  needs only include the speaker  118  in any of the main housing  201 , the first spherical crown  202 , and the second spherical crown  203 . In the present aspect, the robot  100  includes the camera  204  in the first spherical crown  202 . However, this does not imply any limitation. The robot  100  needs only include the camera  204  in any of the main housing  201 , the first spherical crown  202 , and the second spherical crown  203 . Adjusting the locations and number of cameras  204  makes it possible to acquire a 360-degree picture of an area around the robot  100 . In the present aspect, the robot  100  includes the microphone  109  in the first spherical crown  202 . However, this does not imply any limitation. The robot  100  needs only include the microphone  109  in any of the main housing  201 , the first spherical crown  202 , and the second spherical crown  203 . 
     As shown in  FIG. 3 , the robot  100  includes a first display unit  116   a , a second display unit  116   b , and a third display unit  116   c  inside the main housing  201 . The first display unit  116   a , the second display unit  116   b , and the third display unit  116   c  are seated on a fixed metal plate  205 . The fixed metal plate  205  is attached to the shaft via an arm  206 . The first display unit  116   a , the second display unit  116   b , and the third display unit  116   c  are constituted, for example, by a plurality of light-emitting diodes. The first display unit  116   a , the second display unit  116   b , and the third display unit  116   c  display a facial expression of the robot  100 . Specifically, the first display unit  116   a , the second display unit  116   b , and the third display unit  116   c  display a part of the face, e.g. the eyes or mouth, of the robot  100  as shown in  FIG. 2  by individually controlling the turning on of the plurality of light-emitting diodes. In the example shown in  FIGS. 2 and 3 , the first display unit  116   a , the second display unit  116   b , and the third display unit  116   c  display images of the right eye, the left eye, and the mouth, respectively. Moreover, the images of the right eye, the left eye, and the mouth are emitted outward through the main housing  201 , which is composed of a transparent or semitransparent member. 
     As shown in  FIG. 3 , the robot  100  includes a weight  207  in a lower part of the inside of the main housing  201 . For this reason, the robot  100  has its center of gravity located below the center of the main housing  201 . This allows the robot  100  to stably operate. 
       FIG. 4  is a block diagram showing an example of a configuration of the robot  100  according to the embodiment of the present disclosure. 
     The robot  100  includes a processor  11 , a memory  12 , one or more object recognition sensors  101 , one or more microphones  109 , one or more display  116 , one or more speakers  118 , and a movement mechanism  121 . 
     The movement mechanism  121  causes the robot  100  to move. The movement mechanism  121  includes a first drive wheel  210 , a second drive wheel  211 , a first motor  212 , and a second motor  213  (not illustrated). 
     The processor  11  includes a contour detector  102 , an object recognizer  103 , a blind spot determiner  105 , a blind spot counter  107 , a sound recognizer  110 , an intention interpreter  111 , an action executer  112 , an initial position determiner  113 , a main controller  114 , a display information output controller  115 , and a sound information output controller  117 . The memory  12  is for example a nonvolatile semiconductor memory and includes an object position information table  104 , a blind spot map table  106 , a number-of-blind-spots table  108 , a blind spot target object table  119 , and an intention interpretation table  120 . The processor  11  and the memory  12  are disposed in a control circuit  209  (not illustrated). 
     The object recognition sensor  101  is a sensor, attached to the robot  100 , that can recognize the shape of an object. The object recognition sensor  101  includes, for example, at least one of a camera, an infrared sensor, an ultrasonic sensor, and a laser sensor. The object recognition sensor  101  detects an electromagnetic wave or sound wave reflected by an object. A sensor value that is acquired by the object recognition sensor  101  is outputted to the contour detector  102  and the object recognizer  103 . The object recognition sensor  101  includes a camera  208  (not illustrated). 
     The contour detector  102  receives a sensor value from the object recognition sensor  101 , determines the shape of an object in a room, and detects the contours of the object. The contour detector  102  stores, in the object position information table  104 , information indicating the contours of the object thus detected. 
     The object recognizer  103  receives a sensor value from the object recognition sensor  101  and recognizes the class of an object in a room. In making a determination, the object recognizer  103  recognizes what an object is that is installed in the room. An object that the object recognizer  103  recognizes is not limited to an installation, such as a table, a television, or a curtain, that is installed in the room, and the room per se is recognized as an object. The object recognizer  103  stores, in the object position information table  104 , information indicating the class of the object thus recognized. Further, the object recognizer  103  also outputs a recognition result to the main controller  114 . 
     The object position information table  104  receives the contours of an object as detected by the counter detector  102  and the class of the object as recognized by the object recognizer  103  and has stored therein in association with one another an object ID for identifying the object, a position range indicating the contours of the object, and the object class. 
       FIG. 5  is a diagram showing an example of the object position information table  104  according to the present embodiment. An object ID  301  is granted as information that identifies an object in storing its position range and object class. A position range  302  indicates the contours of an object and is detected by the counter detector  102 . The position range  302  in the object position information table  104  represents a region of a room or the object in a two-dimensional plane. The position range  302  is expressed, for example, by an aggregate of coordinates of the apices of a polygon representing the region of the room or the object. An object class  303  indicates the class of an object and is recognized by the object recognizer  103 . 
     The blind spot target object table  119  has stored therein a list of objects that can constitute blind spots for the robot  100  when the robot  100  plays with a young child. The young child is an example of the user, and a target with which the robot  100  interacts is not limited to the young child. 
       FIG. 6  is a diagram showing an example of the blind spot target object table  119  according to the present embodiment. As shown in  FIG. 6 , the blind spot target object table  119  has stored therein blind spot target objects  501  indicating objects that can constitute blind spots for the robot  100  when the robot  100  plays with the young child. Examples of the blind spot target objects  501  include a sofa, a curtain, a futon, a blanket, and a closet. 
     The blind spot determiner  105  refers to the object position information table  104  and the blind spot target object table  119 , compares an object class of the object position information table  104  and a blind spot target object of the blind spot target object table  119  with each other, and creates the blind spot map table  106 . The blind spot  105  determines the object class as a blind spot target in a case where the object class of the object position information table  104  is included in the blind spot target object table  119 . 
       FIG. 7  is a diagram showing an example of the blind spot map table  106  according to the present embodiment. 
     The blind spot determiner  105  creates the blind spot map table  106  that, as illustrated in  FIG. 7 , associates a blind-spot region ID  401 , a position range  402 , a region class  403 , and a blind spot target  404  with one another for each object subjected to a determination as to whether it constitutes a blind spot. The blind spot determiner  105  always monitors changes in value of the object position information table  104 , and in the case of a change in value of the object position information table  104 , the blind spot determiner  105  compares an object class of the object position information table  104  and a blind spot target object of the blind spot target object table  119  with each other and updates the blind spot map table  106 . 
     The blind spot map table  106  is a table that indicates whether individual regions indicating objects in a room become blind spots. As illustrated in  FIG. 7 , the blind spot map table  106  is represented by a set of the blind-spot region ID  401 , the position range  402 , the region class  403 , and the blind spot target  404  and has stored therein for each region information indicating whether it becomes a blind spot target. 
     The blind spot counter  107  divides a region in a room through which the robot  100  is able to move, counts, for each of the plurality of regions thus divided, the number of objects of blind spot target, included in the objects of blind spot target of the blind spot map table  106 , that do not fall within a visual field range of the robot  100  in that region, and stores the number of objects of blind spot target in the number-of-blind-spot table  108 . 
       FIG. 8  is a diagram for explaining the visual field range of the robot  100  according to the present embodiment.  FIG. 9  is a diagram showing examples of a plurality of regions divided according to the number of blind spots according to the present embodiment. 
     In a case where the robot  100  is in a position shown in  FIG. 8 , a visual field range  602  from the robot  100  is a range indicated by diagonal lines. It should be noted that the camera that the robot  100  includes has such a visual field as to be able to shoot 360 degrees in a horizontal direction. The blind spot counter  107  calculates, as the number of blind spots, the number of position ranges of objects of blind spot target of the blind spot map table  106  that do not overlap the visual field range  602  of the robot  100 . In  FIG. 8 , the number of blind spots is 1, as only the position range of the closet, which is an object of blind spot target, does not overlap the visual field range  602 . Once the blind spot counter  107  counts the number of blind spots for all positions in a room shown in  FIG. 8  through which the robot  100  is able to move, the room is divided into a plurality of regions  701  to  708  shown in  FIG. 9 . In  FIG. 9 , the number of blind spots in each of the regions  701 ,  703 , and  705  is 0, the number of blind spots in each of the regions  702 ,  704 , and  706  is 1, and the number of blind spots in each of the regions  707  and  708  is 2. 
     The blind spot counter  107  calculates the number of blind spots in a plurality of positions in the room on the basis of the visual field range of the robot  100  and the positions of objects that constitute blind spot targets, and divides the room into a plurality of regions according to the number of blind spots. The blind spot counter  107  stores number-of-blind-spots IDs granted to identify the plurality of regions, position ranges indicating the respective ranges of the plurality of regions, the respective numbers of blind spots of the plurality of regions, and blind-spot region IDs for identifying the respective blind-spot regions of the plurality of regions in the number-of-blind-spots table  108  in association with one another. 
       FIG. 10  is a diagram showing an example of the number-of-blind-spots table  108  according to the present embodiment. In a case where the regions are divided as shown in  FIG. 9 , the number-of-blind-spots table  108  has information stored therein in a format illustrated in  FIG. 10 . The number-of-blind-spots table  108  (first table) associates the plurality of regions included in the room (predetermined space) and the numbers of blind spots in the plurality of regions with each other. 
     The number-of-blind-spots table  108  is created and updated by the blind spot counter  107 . As shown in  FIG. 10 , the number-of-blind-spots table  108  is represented by a set of a number-of-blind-spots region ID  801 , a position range  802 , the number of blind spots  803 , and a blind-spot region ID  804 , and has stored therein the number of blind spots for each region in the room. The number-of-blind-spots region ID  801  is identification information for identifying each of the plurality of divided regions. The position range  802  in the number-of-blind-spots table  108  represents the plurality of divided regions in a two-dimensional plane. The position range  802  is expressed, for example, by an aggregate of coordinates of the apices of a polygon representing each of the plurality of regions. The blind-spot region ID  804  corresponds to the blind-spot region ID  401  of the blind spot map table  106 . 
     The microphone  109  acquires a sound of an area around the robot  100 . The microphone  109  collects a sound that the young child produces in speaking to the robot  100 , and outputs audio data to the sound recognizer  110 . 
     The sound recognizer  110  receives a sound from the microphone  109  and converts it into a speech text of the young child. On completion of the sound conversion, the sound recognizer  110  outputs the resulting speech text to the intention interpreter  111 . 
     The intention interpreter  111  receives a speech text from the sound recognizer  110  and determines whether the speed text thus received is included in the intention interpretation table  120 . In a case where the intention interpreter  111  has determined that the speed text is included in the intention interpretation table  120 , the intention interpreter  111  determines the content of an action that the robot  100  should execute. The intention interpreter  111  outputs, to the action executer  112  and the main controller  114 , information indicating the content of the action thus determined that the robot  100  should execute. 
       FIG. 11  is a diagram showing an example of the intention interpretation table  120  according to the present embodiment. 
     The intention interpretation table  120  has information stored therein in a format illustrated in  FIG. 11 . The intention interpretation table  120  is represented by a set of a text ID  901  for identifying a speech text, a text  902  indicating the speech text, and an action content  903  indicating an action of the robot  100  corresponding to the speech text. The intention interpreter  111  searches for a text  902  that perfectly or partially matches a speech text received from the sound recognizer  110  and, in a case where there exists a text  902  corresponding to the speech text, extracts an action content  903  corresponding to the text  902 . 
     The action executer  112  receives information indicating the action content  903  from the intention interpreter  111  and executes, on the robot  100 , an action corresponding to the action content thus determined. In playing a game, supposed in the present disclosure, in which the robot  100  seeks for and finds a young child hiding in a room, the action executer  112  instructs the initial position determiner  113  to determine an initial position of the robot  100  in the room at the start of the game. 
     In a case where the intention interpreter  111  has determined that an acquired sound contains a first speech to the effect that the user starts to play hide-and-seek with the robot  100 , the initial position determiner  113  selects, with reference to the number-of-blind-spots table  108  (first table) stored in the memory  12 , a region (first region) where the number of blind spots is smallest in the room (predetermined space). 
     The initial position determiner  113  is called by the action executer  112  to select, with reference to the number-of-blind-spots table  108 , a region where the number of blind spots  803  is smallest. In a case where there exist a plurality of regions where the number of blind spots  803  is smallest, the initial position determiner  113  selects one region from among the plurality of regions. In so doing, there is no particular limit to a method for selecting a region, provided one region is selected. For example, the initial position determiner  113  may randomly select one region from among the plurality of regions where the number of blind spots  803  is smallest or may calculate the area of each region from the position range  802  and selects a region that is largest in area. The initial position determiner  113  instructs the main controller  114  to cause the robot  100  to move to the region thus selected. 
     The main controller  114  receives a region indicating the initial position of the robot  100  from the initial position determiner  113 . At a stage where the region has been designated, the main controller  114  executes a sequence of the game, supposed in the present disclosure, in which the robot  100  seeks for and finds a young child hiding in a room. It should be noted that the game in the present embodiment is hide-and-seek. Further, in hide-and-seek, the young child hides and the robot  100  seeks for the young child. Further, the outcome of usual hide-and-seek is determined by the robot  100  finding (detecting) the young child. However, the outcome of hide-and-seek of the present embodiment is further determined by the robot  100  moving to the blind spot in which the young child is hiding, outputting a sound indicating that the robot  100  has found the young child, and acquiring a speech sound of the young child indicating whether he/she has lost in hide-and-seek. 
     First, the main controller  114  transmits, to the display information output controller  115 , facial expression data to be displayed in preparing for hide-and-seek and transmits, to the sound information output controller  117 , audio data to be outputted in preparing for hide-and-seek. The display information output controller  115  generates a facial expression of the robot  100  on the basis of the facial expression data. The sound information output controller  117  generates a sound of the robot  100  on the basis of the audio data. 
     After that, the main controller  114  instructs the movement mechanism  121  to move to a region that becomes an initial position determined by the initial position determiner  113  and monitors completion of movement of the robot  100 . The main controller  114  controls the movement mechanism  121  to cause the robot  100  to move to a region (first region) selected by the initial position determiner  113 . In accordance with the instruction from the main controller  114 , the movement mechanism  121  causes the robot  100  to move to the initial position. It should be noted that the initial position is for example a center (barycentric) position of the region thus selected. 
     On completion of movement of the robot  100 , the main controller  114  starts hide-and-seek. The main controller  114  transmits, to the display information output controller  115 , facial expression data to be displayed in preparing for hide-and-seek and transmits, to the sound information output controller  117 , audio data to be outputted in preparing for hide-and-seek. The sound information output controller  117  generates, on the basis of the audio data, a first sound indicating the start of hide-and-seek and causes the speaker  118  to output the first sound. The display information output controller  115  generates a facial expression of the robot  100  on the basis of the facial expression data and, in causing the first sound to be outputted, causes the display  116  to display a first display corresponding to the first sound. The display  116  displays the facial expression of the robot  100  with both eyes and the mouth. The first display indicates a smile. 
     Then, the main controller  114  counts a predetermined number. The main controller  114  starts to count time during which the young child hides and, after a predetermined period of time has elapsed, checks with the young child whether he/she has finished hiding. When counting the predetermined number, the main controller  114  causes the object recognition sensor  101  to trace a movement locus of the user. While counting, the main controller  114  tracks a motion of the young child in accordance with data that it receives from the object recognizer  103 . In a case where the main controller  114  has finished counting the predetermined number, the sound information output controller  117  causes the speaker  118  to output a sound indicating that the main controller has finished counting the predetermined number. By receiving, from the intention interpreter  111 , an action of starting seeking or postponing the start of seeking, the main controller  114  checks whether the young child has finished hiding. On receiving the action of starting seeking or postponing the start of seeking, the main controller  114  counts again the time during which the young child hides. 
     In a case where the main controller  114  has determined that a sound acquired by the microphone  109  contains a speech (second speech) indicating that the user has finished hiding, the main controller  114  controls the movement mechanism  121  to cause the robot  100  to move through the entire region in the room (predetermined space) through which the robot  100  is able to move. On receiving the action of starting seeking from the intention interpreter  111 , the main controller  114  instructs the movement mechanism  121  to move through every place in the room in order to find the hiding young child. In accordance with this instruction, the robot  100  starts to move through the inside of the room. 
     While the robot  100  is moving, the main controller  114  receives, from the object recognizer  103 , an image of any object that comes into sight of the robot  100 . In a case where the object recognition sensor  101  has detected the young child by the time the robot  100  finishes moving through the entire region, the sound information output controller  117  causes the speaker  118  to output a sound (third sound) indicating that the robot  100  has won a victory over the young child in hide-and-seek. That is, in a case where the young child, who is a target of seeking, comes into sight of the robot  100  while the robot  100  is moving, the main controller  114  causes the robot  100  to move to the position of the young child, transmits, to the display information output controller  115 , facial expression data indicating that the robot  100  has found the young child, and transmits, to the sound information output controller  117 , audio data indicating the robot  100  has found the young child. 
     In a case where the object recognition sensor  101  has not detected the young child by the time the robot  100  finishes moving through the entire region, the main controller  114  selects, with reference to the blind spot map table  106  (second table) stored in the memory  12 , a blind spot (first blind spot) falling within a predetermined range from an end of the movement locus of the young child. That is, in a case where the young child, who is the target of seeking, comes into sight of the robot  100  while the robot  100  is moving, the main controller  114  extracts, with reference to the blind spot map table  106 , a blind-spot region that lies ahead of the end of the locus of the young child traced during the counting. 
     Further, since the robot  100  stores the movement locus of the young child, the robot  100  can find the young child with a high probability by selecting the blind spot closest to the end of the movement locus, so that there is a possibility that the robot  100  always wins a victory over the young child in hide-and-seek. To address this problem, the robot  100  is configured to lose to the young child in hide-and-seek by intentionally making a mistake with a predetermined probability in finding the position in which the young child is hiding. The main controller  114  determines whether the robot  100  intentionally loses in hide-and-seek. In a case where the main controller  114  has determined that the robot  100  does not intentionally lose, the main controller  114  controls the movement mechanism  121  to cause the robot  100  to move to the blind-spot region (first blind spot) thus extracted. In a case where a plurality of blind-spot regions have been extracted, the main controller  114  selects one blind-spot region as a destination of movement. 
     Further, in a case where the main controller  114  has determined that the robot  100  intentionally loses, the main controller  114  selects, with reference to the blind spot map table  106  (second table), a blind spot (second blind spot) falling outside the predetermined range from the end of the movement locus of the young child. Then, the main controller  114  controls the movement mechanism  121  to cause the robot  100  to move to the blind spot (second blind spot) thus selected. 
     After completion of movement to the blind spot (first blind spot) falling within the predetermined range from the end of the movement locus of the young child or the blind spot (second blind spot) falling outside the predetermined range from the end of the movement locus of the young child, the sound information output controller  117  causes the speaker  118  to output a second sound indicating that the robot  100  has found the young child. In causing the second sound to be outputted, the display information output controller  115  causes the display  116  to display a second display corresponding to the second sound. The second display indicates a smile. That is, the main controller  114  transmits, to the display information output controller  115 , facial expression data indicating that the robot  100  has found the young child, and transmits, to the sound information output controller  117 , audio data indicating that the robot  100  has found the young child. 
     The main controller  114  determines whether a sound acquired by the microphone  109  contains a speech (third speech) indicating an admission of defeat by the young child. In a case where the main controller  114  has determined that the sound acquired by the microphone  109  contains the speech (third speech) indicating an admission of defeat by the young child, the sound information output controller  117  causes the speaker  118  to output a sound (third sound) indicating that the robot  100  has won a victory over the young child in hide-and-seek. In causing the third sound to be outputted, the display information output controller  115  causes the display  116  to display a third display corresponding to the third sound. The third display indicates a smile. In the case of a reception from the intention interpreter  111  to the effect that the young child has made a speech indicating he/she has been found by the robot  100 , the main controller  114  transmits, to the display information output controller  115 , facial expression data indicating that the robot  100  has won, and transmits, to the sound information output controller  117 , audio data indicating that the robot  100  has won. The sound information output controller  117  generates, on the basis of the audio data, the third sound indicating that the robot  100  has won, and causes the speaker  118  to output the third sound. The display information output controller  115  generates, on the basis of the facial expression data, the third display indicating that the robot  100  has won, and causes the display  116  to display the third display. 
     On the other hand, in a case where the intention interpreter  111  has determined that the sound acquired by the microphone  109  does not contain the speech (third speech) indicating an admission of defeat by the young child, the sound information output controller  117  causes the speaker  118  to output a sound (fourth sound) indicating that the robot  100  has lost to the young child in hide-and-seek. In causing the fourth sound to be outputted, the display information output controller  115  causes the display  116  to display a fourth display corresponding to the fourth sound. The fourth sound indicates a facial expression of sorrow. In the case of a reception from the intention interpreter  111  to the effect that the young child has made a speech indicating that the robot  100  has made a mistake in finding the young child, the main controller  114  transmits, to the display information output controller  115 , facial expression data indicating that the robot  100  has been defeated, and transmits, to the sound information output controller  117 , audio data indicating that the robot  100  has been defeated. The sound information output controller  117  generates, on the basis of the audio data, the fourth sound indicating that the robot  100  has been defeated, and causes the speaker  118  to output the fourth sound. The display information output controller  115  generates, on the basis of the facial expression data, the fourth display indicating that the robot  100  has been defeated, and causes the display  116  to display the fourth display. 
     In a case where the intention interpreter  111  has determined that the sound acquired by the microphone  109  does not contain the speech (third speech) indicating an admission of defeat by the young child and where the object recognition sensor  101  has detected the young child hiding in a blind spot (third blind spot) that is not included in the blind spot map table  106  (second table), the main controller  114  may store the third blind spot and the position of the third blind spot in the blind spot map table  106  (second table) in association with each other. That is, in a case where when the robot  100  has been defeated, the place in which the young child was hiding is not included as a blind spot target in the blind spot map table  106 , the main controller  114  may add, as a blind spot target to the blind spot map table  106 , an object placed in the place in which the young child was hiding. 
     The display information output controller  115  receives facial expression data of the robot  100  from the main controller  114  and controls how the display  116  performs a display. 
     The display  116  receives facial expression data from the display information output controller  115  and displays a facial expression of the robot  100 . The display  116  is constituted, for example, by an LED (light-emitting diodes), an LCD (liquid crystal display), or an organic EL (electroluminescence). The display  116  may be constituted by one or more displays and may be configured in any way that can express a facial expression of the robot  100 . In the present embodiment, the display  116  includes the first to third display unit  116   a , the second display unit  116   b , and the third display unit  116   c , which are shown in  FIG. 3 . 
     The sound information output controller  117  receives audio data of the robot  100  from the main controller  114  and controls how the speaker  118  outputs a sound. 
     The speaker  118  receives audio data from the sound information output controller  117  and reproduces the audio data thus received. 
     The interaction apparatus  200  includes the processor  11 , the memory  12 , the object recognition sensor  101 , the microphone  109 , the display  116 , the speaker  118 , and the movement mechanism  121 . The interaction apparatus  200  does not need to include the display  116 . 
     Further, some or all of the components of the processor  11  and the memory  12  may be provided in a server communicably connected to the robot  100  via a network. 
     In the following, processes for creating and updating the object position information table  104 , the blind spot map table  106 , and the number-of-blind-spots table  108  from data of the object recognition sensor  101  are described with reference to  FIGS. 12, 13, and 14 , respectively. 
       FIG. 12  is a flow chart showing an example of the process for creating the object position information table  104  on the basis of the data of the object recognition sensor  101  according to the present embodiment. 
     First, in step S 1 , in order to create the object position information table  104 , the main controller  114  instructs the movement mechanism  121  so that the robot  100  randomly moves through a region in a room through which the robot  100  is able to move. Autonomously or in accordance with an instruction from the user, the main controller  114  starts a movement to create the object position information table  104 . In autonomously creating the object position information table  104 , the main controller  114  may start, for example every one day or every one week, a movement to create the object position information table  104 . Although step S 1  assumes that the robot  100  randomly moves, the robot  100  does not need to randomly move, provided the robot  100  is able to move through every place in the region in the room through which the robot  100  is able to move. In accordance with the instruction from the main controller  114 , the movement mechanism  121  causes the robot  100  to randomly move. 
     Next, in step S 2 , the main controller  114  instructs the object recognition sensor  101  to photograph the inside of the room while the robot  100  is moving. The object recognition sensor  101  photographs the inside of the room and outputs photographed data to the contour detector  102  and the object recognizer  103 . 
     Next, in step S 3 , the contour detector  102  detects the contours of the room and the contours of an object in the room using the photographed data outputted from the object recognition sensor  101 . 
     Next, in step S 4 , the object recognizer  103  recognizes the class of the room and the class of the object in the room using the photographed data outputted from the object recognition sensor  101 . 
     Next, in step S 5 , the contour detector  102  stores the contours of the room and the contours of the object in the room as position ranges in the object position information table  104 , and the object recognizer  103  stores the class of the room and the class of the object in the room as object classes in the object position information table  104 . In a case where only the contour detector  102  has stored a position range in the object position information table  104 , only the object ID  301  and the position range  302  are stored. 
     Next, in step S 6 , the main controller  114  determines whether the robot  100  has moved through the whole of the region through which the robot  100  is able to move. In a case where the main controller  114  has determined here that the robot  100  has moved through the whole of the region through which the robot  100  is able to move (YES in step S 6 ), the process is ended. 
     On the other hand, In a case where the main controller  114  has determined that the robot  100  has not moved through the whole of the region through which the robot  100  is able to move (NO in step S 6 ), the process returns to step S 1 . 
       FIG. 13  is a flow chart showing an example of the process for creating the blind spot map table  106  on the basis of data of the object position information table  104  according to the present embodiment. 
     First, in step S 11 , the blind spot determiner  105  monitors a change to the object position information table  104 . 
     Next, in step S 12 , the blind spot determiner  105  determines whether the object position information table  104  has been changed. In a case where the blind spot determiner  105  has determined here that the object position information table  104  has not been changed (NO in step S 12 ), the process returns to step S 11 . 
     On the other hand, in a case where the blind spot determiner  105  has determined that the object position information table  104  has been changed (YES in step S 12 ), the process proceeds to step S 13 , in which the blind spot determiner  105  refers to the blind spot target object table  119  to acquire a list of objects that the robot  100  judges as blind spot targets. 
     Next, in step S 14 , the blind spot determiner  105  compares the object position information table  104  and the blind spot target object table  119  with each other to identify, from among object classes stored in the object position information table  104 , an object class that constitutes a blind spot target for the robot  100 . In the case of the layout of  FIG. 1 , the blind spot determiner  105  identifies the sofa  1002 , the closet  1003 , and the curtain  1004  as object classes that constitute blind spot targets. 
     Next, in step S 15 , the blind spot determiner  105  stores information indicating whether an object class constitutes a blind spot target in the blind spot map table  106  in association with each region class. The blind spot determiner  105  stores position ranges and object classes stored in the object position information table  104  as position ranges and region classes in the blind spot map table  106 . 
       FIG. 14  is a flow chart showing an example of the process for creating and updating the number-of-blind-spots table  108  on the basis of data of the blind spot map table  106  according to the present embodiment. 
     First, in step S 21 , the blind spot counter  107  monitors a change to the blind spot map table  106 . 
     Next, in step S 22 , the blind spot counter  107  determines whether the blind spot map table  106  has been changed. In a case where the blind spot counter  107  has determined here that the blind spot map table  106  has not been changed (NO in step S 22 ), the process returns to step S 21 . 
     On the other hand, in a case where the blind spot counter  107  has determined that the blind spot map table  106  has been changed (YES in step S 22 ), the process proceeds to step S 23 , in which in order to count, at each set of coordinates of the region in the room through which the robot  100  is able to move, the number of blind-spot regions falling outside a visual field range that can be seen from a point of view of the robot  100 , the blind spot counter  107  randomly selects one set of coordinates from the region in the room through which the robot  100  is able to move. For example, the blind point counter  107  selects coordinates corresponding to the position of the robot  100  shown in  FIG. 8 . 
     Next, in step S 24 , the blind spot counter  107  calculates the visual field range of the robot  100  at the coordinates thus selected and counts the number of regions of blind spot target that are present outside the visual field range. In the example shown in  FIG. 8 , the number of blind spots is 1, as the closet is the only blind spot target that is present outside the visual field range  602  of the robot  100 . In so doing, it is preferable that the blind spot counter  107  make the number of blind spots at all coordinates falling within a circle of a predetermined radius centered at the coordinates at which the number of blind spots was counted equal to the number of blind spots thus counted. For example, the blind spot counter  107  may make the number of blind spots at coordinates falling within a circle having a radius of 10 cm equal to the number of blind spots at the coordinates of the center. Although it is assumed here that the number of blind spots at all coordinates falling within a circle of a predetermined radius centered at the coordinates at which the number of blind spots was counted is equal to the number of blind spots thus counted, the circle does not necessarily imply any limitation. This makes it possible to eliminate the process for counting the number of blind spots. 
     Next, in step S 25 , the blind spot counter  107  determines whether it has counted the number of blind spots at all of the coordinates of the region in the room through which the robot  100  is able to move. 
     In a case where the blind spot counter  107  has determined here that it has not counted the number of blind spots at all of the coordinates (NO in step S 25 ), the process proceeds to step S 26 , in which the blind spot counter  107  selects, from the region in the room through which the robot  100  is able to move, other coordinates at which the number of blind spots has not been counted, and the process returns to step S 24 . 
     On the other hand, in a case where the blind spot counter  107  has determined here that it has counted the number of blind spots at all of the coordinates (YES in step S 25 ), the process proceeds to step S 27 , in which the blind spot counter  107  divides the region in the room through which the robot  100  is able to move into a plurality of regions according to the number of blind spots thus counted and stores the number of blind spots in the number-of-blind-spots table  108  in association with each of the regions thus divided. That is, the blind spot counter  107  stores a number-of-blind-spots ID that identifies each of the regions thus divided, a position range indicating the range of each of the regions thus divided, the number of blind spots of each of the regions thus divided, and a blind-spot region ID for identifying the blind-spot region of each of the regions thus divided in the number-of-blind-spots table  108  in association with one another. The blind spot counter  107  divides the region in the room through which the robot  100  is able to move into regions constituted by coordinates at which the numbers of blind spots counted are equal. 
     In the present embodiment, in the case of discovery of coordinates at which there is no region of blind spot target outside the visual field range, i.e. in the case of discovery of coordinates at which the number of blind spots counted is 0, the blind spot counter  107  may execute step S 27  without selecting other coordinates at that point of time. 
     In the following, a process by which the robot  100  finds a young child hiding in a room is described with reference to  FIGS. 15, 16, and 17 . 
       FIG. 15  is a first flow chart for explaining an example of the process by which the robot  100  and the young child play hide-and-seek according to the present embodiment.  FIG. 16  is a second flow chart for explaining the example of the process by which the robot and the young child play hide-and-seek according to the present embodiment.  FIG. 17  is a third flow chart for explaining the example of the process by which the robot and the young child play hide-and-seek according to the present embodiment. 
     First, in step S 31 , the intention interpreter  111  determines whether a sound acquired by the microphone  109  contains a first speech to the effect that hide-and-seek is started. In starting hide-and-seek, the young child uses his/her voice to announce his/her intention to want to play hide-and-seek. The intention interpreter  111  determines whether the content of a speech made by the young child is a speech indicating that hide-and-seek is started. 
     In a case where the intention interpreter  111  has determined that the sound thus acquired does not contain the first speech to the effect that hide-and-seek is started (NO in step S 31 ), the determination process of step S 31  is repeatedly executed. 
     On the other hand, in a case where the intention interpreter  111  has determined that the sound thus acquired contains the first speech to the effect that hide-and-seek is started (YES in step S 31 ), the action executer  112  instructs the initial position determiner  113  to determine the initial position of the robot  100  in the room so that hide-and-seek is started. 
     Next, in step S 33 , the initial position determiner  113  selects, from the number-of-blind-spots table  108 , a region where the number of blind spots is smallest, and determines the region thus selected as the initial position of the robot  100 . In a case where there exist a plurality of regions where the number of blind spots is smallest, the initial position determiner  113  selects one region from among the plurality of regions. The initial position determiner  113  may randomly select one region from among the plurality of regions or may select, from among the plurality of regions, a region that is largest in area. There is no particular limit to a method for selecting one region from among the plurality of regions where the number of blind spots is smallest. 
     Since a region where the number of blind spots is smallest is thus determined as the initial position of the robot  100 , the largest number of blind-spot regions can be put within the visual field of the camera, so that the locus of a movement of the young child hiding in a blind-spot region can be more accurately traced. 
     Next, in step S 34 , in order to respond to the speech made by the young child to start hide-and-seek, the sound information output controller  117  outputs a sound indicating a response to the first speech to the effect that hide-and-seek is started. 
       FIG. 18  is a diagram showing examples of speech text patterns that are outputted from the speaker  118  according to the present embodiment. The memory  12  of the robot  100  has stored therein a speech text pattern table shown in  FIG. 18 . The speech text pattern table is a table in which speech IDs  1601  for identifying from one situation to another the texts of speeches that the robot  100  makes and speech texts  1602  of speeches that the robot  100  makes in various situations are associated with each other. In response to the first speech to the effect that hide-and-seek is started, the sound information output controller  117  for example selects a speech text  1602  corresponding to a speech ID  1601  of “1” shown in  FIG. 18 , converts the speech text  1602  thus selected into a sound, and outputs the sound from the speaker  118 . In the present embodiment, in a case where a plurality of speech texts are associated with one speech ID, the sound information output controller  117  randomly selects one speech text from among the plurality of speech texts. 
     Next, in step S 35 , in order to respond to the speech made by the young child to start hide-and-seek, the display information output controller  115  displays a facial expression indicating a response to the first speech to the effect that hide-and-seek is started. 
       FIG. 19  is a diagram showing examples of expression patterns that are displayed on the display  116  according to the present embodiment. The memory  12  of the robot  100  has stored therein a facial expression pattern table shown in  FIG. 19 . The facial expression pattern table is a table in which facial expression IDs  1701  for identifying from one situation to another facial expressions that the robot  100  displays and facial expression patterns  1702  that the robot  100  displays in various situations are associated with each other. In response to the first speech to the effect that hide-and-seek is started, the display information output controller  115  for example selects a facial expression pattern  1702  corresponding to a facial expression ID  1701  of “1” shown in  FIG. 19  and displays, on the display  116 , the facial expression  1702  thus selected. In the present embodiment, in a case where a plurality of facial expression patterns are associated with one facial expression ID, the display information output controller  115  randomly selects one facial expression pattern from among the plurality of facial expression patterns. 
     Next, in step S 36 , the main controller  114  controls the movement mechanism  121  to cause the robot  100  to move to the region thus selected. The main controller  114  instructs the movement mechanism  121  to cause the robot  100  to move to the region thus selected. In accordance with the instruction from the main controller  114 , the movement mechanism  121  causes the robot  100  to move to the region thus selected. For example, the main controller  114  causes the robot  100  to move to the barycentric position of the region thus selected. 
     Next, in step S 37 , the sound information output controller  117  outputs, from the speaker  118 , a sound (first sound) indicating the start of hide-and-seek. In outputting the sound indicating the start of hide-and-seek, the sound information output controller  117  for example selects a speech text  1602  corresponding to a speech ID  1601  of “2” shown in  FIG. 18 , converts the speech text  1602  thus selected into a sound, and outputs the sound from the speaker  118 . In the present embodiment, in a case where a plurality of speech texts are associated with one speech ID, the sound information output controller  117  randomly selects one speech text from among the plurality of speech texts. 
     Next, in step S 38 , the display information output controller  115  displays, on the display  116 , a facial expression (first display) indicating the start of hide-and-seek. In displaying the facial expression indicating the start of hide-and-seek, the display information output controller  115  for example selects a facial expression pattern  1702  corresponding to a facial expression ID  1701  of “2” shown in  FIG. 19  and displays, on the display  116 , the facial expression  1702  thus selected. In the present embodiment, in a case where a plurality of facial expression patterns are associated with one facial expression ID, the display information output controller  115  randomly selects one facial expression pattern from among the plurality of facial expression patterns. 
     After step S 38 , the young child starts hide-and-seek and moves through the inside of the room in order to hide. 
     Next, in step S 39 , the display information output controller  115  displays, on the display  116 , a facial expression indicating that the robot  100  is not watching the young child. In displaying the facial expression indicating that the robot  100  is not watching the young child, the display information output controller  115  for example selects a facial expression pattern  1702  corresponding to a facial expression ID  1701  of “4” shown in  FIG. 19  and displays, on the display  116 , the facial expression  1702  thus selected. In the present embodiment, in a case where a plurality of facial expression patterns are associated with one facial expression ID, the display information output controller  115  randomly selects one facial expression pattern from among the plurality of facial expression patterns. 
     Next, in step S 40 , the main controller  114  starts to count time during which for the young child to hide in the room. Time until the end of the counting is set in advance. For example, a period of 30 seconds or 1 minute is set in advance. 
     Next, in step S 41 , while counting time, the main controller  114  uses the recognition sensor  101  and the object recognizer  103  to trace a movement locus of the young child. The main controller  114  treats the position of the young child in the room at the start of the counting as a starting point and traces the movement locus of the young child from the starting point. The main controller  114  stores, in the memory  12 , the movement locus of the young child thus traced. 
     Next, in step S 42 , the sound information output controller  117  outputs, from the speaker  118 , a sound indicating the end of the counting. In outputting the sound indicating the end of the counting, the sound information output controller  117  for example selects a speech text  1602  corresponding to a speech ID  1601  of “3” shown in  FIG. 18 , converts the speech text  1602  thus selected into a sound, and outputs the sound from the speaker  118 . In the present embodiment, in a case where a plurality of speech texts are associated with one speech ID, the sound information output controller  117  randomly selects one speech text from among the plurality of speech texts. 
     Next, in step S 43 , the intention interpreter  111  determines whether a sound acquired by the microphone  109  contains a second speech indicating that the young child has finished hiding. 
     In a case where the intention interpreter  111  has determined here that the sound thus acquired does not contain the second speech indicating that the young child has finished hiding (NO in step S 43 ), the process returns to step S 40 . In a case where the sound thus acquired does not contain the second speech indicating that the young child has finished hiding, the intention interpreter  111  may determine whether the sound thus acquired contains a speech indicating a postponement of the start of seeking. In a case where the intention interpreter  111  has determined that the sound thus acquired contains a speech indicating a postponement of the start of seeking, the process may return to step S 40 . In a case where the intention interpreter  111  has determined that the sound thus acquired does not contain a speech indicating a postponement of the start of seeking, the process may proceed to step S 44 , as it is estimated that the young child has finished hiding. 
     On the other hand, in a case where the intention interpreter  111  has determined here that the sound thus acquired contains the second speech indicating that the young child has finished hiding (YES in step S 43 ), the process proceeds to step S 44 , in which the action executer  112  instructs the main controller  114  to start to seek for the young child. 
     Next, in step S 45 , the sound information output controller  117  outputs, from the speaker  118 , a sound indicating the start of seeking for the young child. In outputting the sound indicating the start of seeking for the young child, the sound information output controller  117  for example selects a speech text  1602  corresponding to a speech ID  1601  of “4” shown in  FIG. 18 , converts the speech text  1602  thus selected into a sound, and outputs the sound from the speaker  118 . In the present embodiment, in a case where a plurality of speech texts are associated with one speech ID, the sound information output controller  117  randomly selects one speech text from among the plurality of speech texts. 
     Next, in step S 46 , the display information output controller  115  displays, on the display  116 , a facial expression indicating the start of seeking for the young child. In displaying the facial expression indicating the start of seeking for the young child, the display information output controller  115  for example selects a facial expression pattern  1702  corresponding to a facial expression ID  1701  of “1” shown in  FIG. 19  and displays, on the display  116 , the facial expression  1702  thus selected. In the present embodiment, in a case where a plurality of facial expression patterns are associated with one facial expression ID, the display information output controller  115  randomly selects one facial expression pattern from among the plurality of facial expression patterns. 
     Next, in step S 47 , on receiving the instruction to start to seek for the young child, the main controller  114  controls the movement mechanism  121  to cause the robot  100  to start to move. At this point in time, the main controller  114  controls the movement mechanism  121  to cause the robot  100  to move through the entire region in the room through which the robot  100  is able to move. In so doing, the main controller  114  may cause the robot  100  to randomly move to search everywhere in the entire room or may move while storing a movement locus of the robot  100  so as to reduce the number of regions through which the robot  100  has not moved. There is no particular limit to how to move. Further, the main controller  114  seeks for the young child during a movement. At this point in time, the main controller  114  uses the object recognition sensor  101  and the object recognizer  103  to seek for the young child so as to detect the face of the young child stored in advance. The face of the young child may be stored at the start of hide-and-seek such as a period of time between step S 39  and step S 40 , or may be user-registered in advance. 
     Next, in step S 48 , the main controller  114  determines whether the young child, who is the target of seeking, has been detected by the object recognition sensor  101  and the object recognizer  103  while the robot  100  is moving. In a case where the main controller  114  has determined that the young child, who is the target of seeking, has been detected during the movement (YES in step S 48 ), the process proceeds to step S 55 . 
     On the other hand, in a case where the main controller  114  has determined that the young child, who is the target of seeking, has not been detected during the movement (NO in step S 48 ), the process proceeds to step S 49 , in which the main controller  114  determines whether the robot  100  has finished moving through the entire region in the room through which the robot  100  is able to move. In a case where the main controller  114  has determined here that the robot  100  has not finished moving through the entire region in the room through which the robot  100  is able to move (NO in step S 49 ), the process returns to step S 48 . 
     On the other hand, in a case where the main controller  114  has determined here that the robot  100  has finished moving through the entire region in the room through which the robot  100  is able to move (YES in step S 49 ), the process proceeds to step S 50 , in which by utilizing the movement locus of the young child traced, the main controller  114  selects, from the blind spot map table  106 , a first blind-spot region that is present within a predetermined range from an end of the movement locus of the young child. In a case where a plurality of blind-spot regions are present within the predetermined range from the end of the movement locus, the main controller  114  selects one blind-spot region from among the plurality of blind-spot regions falling within the predetermined range. At this point in time, the main controller  114  may randomly select one blind-spot region from among the plurality of blind-spot regions falling within the predetermined range or may select one blind-spot region that is closest to the end from among the plurality of blind-spot regions falling within the predetermined range. 
     Next, in step S 51 , the main controller  114  determines whether the robot  100  intentionally loses. At this point in time, the main controller  114  randomly determines whether the robot  100  intentionally loses. A probability of intentional losing is designated in advance for the robot  100 . 
     In a case where the main controller  114  has determined that the robot  100  does not intentionally lose (NO in step S 51 ), the process proceeds to step S 52 , in which the main controller  114  controls the movement mechanism  121  to cause the robot  100  to move to the first blind-spot region thus selected. 
     On the other hand, in a case where the main controller  114  has determined that the robot  100  intentionally loses (YES in step S 51 ), the process proceeds to step S 53 , in which by utilizing the movement locus of the young child traced, the main controller  114  selects, from the blind spot map table  106 , a second blind-spot region that is present outside the predetermined range from the end of the movement locus of the young child. In a case where a plurality of blind-spot regions are present outside the predetermined range from the end of the movement locus of the young child, the main controller  114  selects one blind-spot region from among the plurality of blind-spot regions falling outside the predetermined range. At this point in time, the main controller  114  may randomly select one blind-spot region from among the plurality of blind-spot regions falling outside the predetermined range or may select one blind-spot region that is farthest from the end from among the plurality of blind-spot regions falling outside the predetermined range. 
     Next, in step S 54 , the main controller  114  controls the movement mechanism  121  to cause the robot  100  to move to the second blind-spot region thus selected. 
     Next, in step S 55 , the sound information output controller  117  outputs, from the speaker  118 , a sound (second sound) indicating that the robot  100  has found the young child. In outputting the sound indicating that the robot  100  has found the young child, the sound information output controller  117  for example selects a speech text  1602  corresponding to a speech ID  1601  of “5” shown in  FIG. 18 , converts the speech text  1602  thus selected into a sound, and outputs the sound from the speaker  118 . In the present embodiment, in a case where a plurality of speech texts are associated with one speech ID, the sound information output controller  117  randomly selects one speech text from among the plurality of speech texts. 
     Next, in step S 56 , the display information output controller  115  displays, on the display  116 , a display (second display) indicating that the robot  100  has found the young child. In displaying the facial expression indicating that the robot  100  has found the young child, the display information output controller  115  for example selects a facial expression pattern  1702  corresponding to a facial expression ID  1701  of “2” shown in  FIG. 19  and displays, on the display  116 , the facial expression  1702  thus selected. In the present embodiment, in a case where a plurality of facial expression patterns are associated with one facial expression ID, the display information output controller  115  randomly selects one facial expression pattern from among the plurality of facial expression patterns. 
     In a case where steps S 55  and S 56  have been executed after the main controller  114  has determined in step S 48  that the young child, who is the target of seeking, has been detected while the robot  100  is moving, the hide-and-seek process may be ended, as it is clear that the robot  100  has won. 
     Next, in step S 57 , the intention interpreter  111  determines whether a sound acquired by the microphone  109  contains a third sound indicating an admission of defeat by the young child, who is the target of seeking. 
     In a case where the intention interpreter  111  has determined that the sound thus acquired contains the third speech indicating an admission of defeat by the young child, who is the target of seeking (YES in step S 57 ), the process proceeds to step S 58 , in which the sound information output controller  117  outputs, from the speaker  118 , a sound (third sound) indicating that the robot  100  has won a victory over the young child in hide-and-seek. In outputting the sound indicating that the robot  100  has won a victory over the young child in hide-and-seek, the sound information output controller  117  for example selects a speech text  1602  corresponding to a speech ID  1601  of “6” shown in  FIG. 18 , converts the speech text  1602  thus selected into a sound, and outputs the sound from the speaker  118 . In the present embodiment, in a case where a plurality of speech texts are associated with one speech ID, the sound information output controller  117  randomly selects one speech text from among the plurality of speech texts. 
     Next, in step S 59 , the display information output controller  115  displays, on the display  116 , a facial expression (third display) indicating that the robot  100  has won a victory over the young child in hide-and-seek. In displaying the facial expression indicating that the robot  100  has won a victory over the young child in hide-and-seek, the display information output controller  115  for example selects a facial expression pattern  1702  corresponding to a facial expression ID  1701  of “2” shown in  FIG. 19  and displays, on the display  116 , the facial expression  1702  thus selected. In the present embodiment, in a case where a plurality of facial expression patterns are associated with one facial expression ID, the display information output controller  115  randomly selects one facial expression pattern from among the plurality of facial expression patterns. 
     On the other hand, in a case where the intention interpreter  111  has determined that the sound thus acquired does not contain the third speech indicating an admission of defeat by the young child, who is the target of seeking (NO in step S 57 ), the process proceeds to step S 60 , in which the sound information output controller  117  outputs, from the speaker  118 , a sound (fourth sound) indicating that the robot  100  has lost to the young child in hide-and-seek. In outputting the sound indicating that the robot  100  has lost to the young child in hide-and-seek, the sound information output controller  117  for example selects a speech text  1602  corresponding to a speech ID  1601  of “7” shown in  FIG. 18 , converts the speech text  1602  thus selected into a sound, and outputs the sound from the speaker  118 . In the present embodiment, in a case where a plurality of speech texts are associated with one speech ID, the sound information output controller  117  randomly selects one speech text from among the plurality of speech texts. 
     Next, in step S 61 , the display information output controller  115  displays, on the display  116 , a facial expression (fourth display) indicating that the robot  100  has lost to the young child in hide-and-seek. In displaying the facial expression indicating that the robot  100  has lost to the young child in hide-and-seek, the display information output controller  115  for example selects a facial expression pattern  1702  corresponding to a facial expression ID  1701  of “3” shown in  FIG. 19  and displays, on the display  116 , the facial expression  1702  thus selected. In the present embodiment, in a case where a plurality of facial expression patterns are associated with one facial expression ID, the display information output controller  115  randomly selects one facial expression pattern from among the plurality of facial expression patterns. 
     Thus, after the movement locus of the young child has been traced by the object recognition sensor  101  when the predetermined number has been counted and the young child is hiding in the first region where the number of blind spots is smallest in the space, a movement to the entire region through which the robot  100  is able to move is started, and in a case where the object recognition sensor  101  has not detected the young child by the time the robot  100  finishes moving through the entire region, the first blind-spot region falling within the predetermined range from the end of the movement locus of the young child is selected and the robot  100  is moved to the first blind-spot region. Note here that the first blind spot can be said to be a blind spot in which the young child is highly likely to have hidden, as the first blind spot falls within the predetermined range from the end of the movement locus of the young child. This makes it possible to identify a blind spot in which the young child is highly likely to be hiding and that cannot been seen from the robot  100 . 
     Next, in step S 62 , the main controller  114  uses the object recognition sensor  101  and the object recognizer  103  to detect the young child, who is the target of seeking. 
     Next, in step S 63 , the main controller  114  determines whether a region corresponding to the position of the young child, who is the target of seeking, thus detected is registered as a blind spot target in the blind spot map table  106 . In a case where the main controller  114  has determined that the region corresponding to the position of the young child, who is the target of seeking, is registered as a blind spot target in the blind spot map table  106  (YES in step S 63 ), the hide-and-seek process is ended. 
     On the other hand, in a case where the main controller  114  has determined that the region corresponding to the position of the young child, who is the target of seeking, is not registered as a blind spot target in the blind spot map table  106  (NO in step S 63 ), the process proceeds to step S 64 , in which the main controller  114  registers the region corresponding to the position of detection of the young child as a blind spot target in the blind spot map table  106  and updates the blind spot map table  106 . 
     For example, in the blind spot map table  106  of  FIG. 7 , the door is not registered as a blind spot target; therefore, in a case where the young child is hiding in the gap between the door and the wall of  FIG. 1 , the robot  100  cannot identify the position in which the young child is hiding. However, once the young child is detected in a gap  1001  between the door and the wall after the robot  100  has lost, a region corresponding to the position of the door where the young child has been detected is registered as a blind spot target in the blind spot map table  106  and the blind spot map table  106  is updated. This allows the robot  100  to select the door as a blind-spot region in playing a next round of hide-and-seek and identify the gap  1001  between the door and the wall as a position in which the young child is hiding. 
     In the present disclosure, all or a part of any of unit, device, part or portion, or any of functional blocks in the illustrated block diagrams may be implemented as one or more of electronic circuits including, but not limited to, a semiconductor device, a semiconductor integrated circuit (IC) or an LSI. The LSI or IC can be integrated into one chip, or also can be a combination of plural chips. For example, functional blocks other than a memory may be integrated into one chip. The name used here is LSI or IC, but it may also be called system LSI, VLSI (very large scale integration), or ULSI (ultra large scale integration) depending on the degree of integration. A Field Programmable Gate Array (FPGA) that can be programmed after manufacturing an LSI or a reconfigurable logic device that allows reconfiguration of the connection or setup of circuit cells inside the LSI can be used for the same purpose. 
     Further, it is also possible that all or a part of the functions or operations of the unit, device, part or portion are implemented by executing software. In such a case, the software is recorded on one or more non-transitory recording media such as a ROM, an optical disk or a hard disk drive, and when the software is executed by a processor, the software causes the processor together with peripheral devices to execute the functions specified in the software. A system or apparatus may include such one or more non-transitory recording media on which the software is recorded and a processor together with necessary hardware devices such as an interface. 
     An apparatus, a method, a recording medium storing a program, and a robot according to the present disclosure are useful as an apparatus, a method, a recording medium storing a program, and a robot that make it possible to identify a blind spot in which a user is highly likely to be hiding and that cannot be seen from the apparatus.