Patent Publication Number: US-10777183-B2

Title: Control apparatus, control system, and control method

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a control apparatus, a control system, and a control method for an unmanned flying object. 
     2. Description of the Related Art 
     Concerning an unmanned flying object, Japanese Unexamined Patent Application Publication No. 2017-9965 (Patent Literature 1) proposes a wireless aircraft capable of reducing undesired sound while maintaining flying performance of an apparatus body. Specifically, the wireless aircraft described in Patent Literature 1 flies in the air with a rotor blade (a propeller) rotated by a motor. The wireless aircraft described in Patent Literature 1 collects rotation sound of the motor, generates an acoustic wave having an opposite phase of the phase of the collected rotation sound, collects ambient sound, and combines the acoustic wave having the opposite phase of the phase of the collected rotation sound with the collected sound to perform so-called active noise cancelling (ANC). 
     SUMMARY 
     For example, a speaker for outputting sound having the opposite phase is mounted on the unmanned flying object. An effect of the ANC is exerted on the periphery of the unmanned flying object. However, there are limits in the magnitude of the output and performance such as directivity of the speaker. It is difficult to exert the effect of the ANC in a wide range. 
     One non-limiting and exemplary embodiment provides a control apparatus and the like that can expand a range in which undesired sound generated in an unmanned flying object is reduced. 
     In one general aspect, the techniques disclosed here feature a control apparatus including: a processor; and a memory including at least one set of instructions that, when executed by the processor, causes the processor to perform operations including: acquiring position information of one or more unmanned flying objects and noise information concerning first noises generated by the one or more unmanned flying objects; acquiring output region information indicating an output region of sound output from a speaker; calculating, using the position information, the output region information, and the noise information, second noises that reach the output region, with the second noises being caused by the first noises which are generated by the one or more unmanned flying objects; generating opposite phase signals for outputting opposite phase sounds with respect to the calculated second noises; and causing the speaker to output sound on a basis of the generated opposite phase signals. 
     With the control apparatus and the like according to the aspect of the present disclosure, a range in which undesired sound generated in the unmanned flying object is reduced can be expanded. 
     It should be note that these comprehensive and specific aspects may be realized by a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM or may be realized by any combination of the system, the apparatus, the method, the integrated circuit, the computer program, and the recording medium. 
     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 schematically illustrating the configurations of a control system and an unmanned flying object in a first embodiment; 
         FIG. 2  is a flowchart illustrating an example of the operation of a control apparatus in the first embodiment; 
         FIG. 3  is a diagram schematically illustrating the configurations of a control system, an unmanned flying object, and a control center in a modification of the first embodiment; and 
         FIG. 4  is a diagram schematically illustrating the configurations of a control system and an unmanned flying object in a second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Underlying Knowledge Forming Basis of the Present Disclosure 
     In recent years, an unmanned flying object represented as a drone, an unmanned aircraft, or a UAV (Unmanned Aerial Vehicle) as well has been started to be used. For example, by flying an unmanned flying object mounted with a camera and a microphone high in the air, photographing and sound collection can be performed in a place where people cannot easily reach. Such an unmanned flying object can be used in, for example, an outdoor event site. 
     On the other hand, basically, undesired sound generated by the unmanned flying object (mainly undesired sound generated by rotation of a rotor blade) is large. It is desired to reduce the undesired sound. Therefore, for example, it is conceivable to apply a technique (ANC) for collecting undesired sound (a reference signal) generated by the unmanned flying object and reduce the undesired sound. 
     The ANC is a technique for actively reducing noise such as undesired sound with opposite phase sound. Note that a technique for reducing only undesired sound from sound is also present. For example, undesired sound (a reference signal) is collected and opposite phase sound of the undesired sound is output from a speaker, whereby the undesired sound is reduced. The opposite phase sound of the undesired sound (the reference signal) is sound having an opposite phase to the phase of the undesired sound and is sound having a reversed waveform of a waveform of the undesired sound. Consequently, the sound collected as the undesired sound is reduced. 
     To apply such ANC, for example, a speaker for outputting sound having an opposite phase is mounted on the unmanned flying object. An effect of the ANC is exerted on the periphery of the unmanned flying object. However, there are limits in the magnitude of the output and performance such as directivity of the speaker. It is difficult to exert the effect of the ANC in a wide range. To cause the speaker to output sound having an opposite phase for reducing undesired sound (noise) in a low-frequency region, the weight of the speaker needs to be increased. This affects flight of the unmanned flying object. 
     A control apparatus according to an aspect of the present disclosure is a control apparatus including: a processor; and a memory including at least one set of instructions that, when executed by the processor, causes the processor to perform operations including: acquiring position information of one or more unmanned flying objects and noise information concerning first noises generated by the one or more unmanned flying objects; acquiring output region information indicating an output region of sound output from a speaker; calculating, using the position information, the output region information, and the noise information, second noises that reach the output region, with the second noises being caused by the first noises which are generated by the one or more unmanned flying objects; generating opposite phase signals for outputting opposite phase sounds with respect to the calculated second noises; and causing the speaker to output sound on a basis of the generated opposite phase signals. 
     The first noise generated from the unmanned flying object is, for example, attenuated by space propagation or reflected on a building before the first noise reaches the output region. In the output region, the first noise changes from the first noise at the time of the generation in the unmanned flying object. Therefore, when the output region of the sound output from the speaker and a generation source of the first noise are apart from each other, simply by generating the signal having the opposite phase of the phase of the first noise that is, for example, not attenuated at the time of the generation in the unmanned flying object, even if the sound is output from the speaker on the basis of the signal, the noise cannot be accurately reduced in the output region. On the other hand, according to the present disclosure, the second noise generated from the unmanned flying object and reaching the output region, that is, noise changing from the first noise at the time of the generation in the unmanned flying object is calculated. Therefore, the speaker can be disposed in the periphery of the output region, which is a region where noise is desired to be reduced such as the ground away from the unmanned flying object. Therefore, the speaker may not be mounted on the unmanned flying object. A weight on board of the unmanned flying object can be reduced. When the speaker is not mounted on the unmanned flying object, there is no limit in the weight and the like of the speaker. Therefore, the speaker can be increased in size in order to improve the performance of the speaker. A plurality of speakers can be used. Consequently, a range in which undesired sound can be reduce can be expanded. 
     Preferably, in the control apparatus of the present disclosure, the operations further include: acquiring time information indicating a generation time of the first noises; calculating, from the position information, the output region information, and the time information, a reaching time of the second noises that reach the output region; and causing the speaker to output the sound on the basis of the generated opposite phase signals according to the calculated reaching time. 
     It is desirable to synchronize, with arrival of the noise, timing for outputting, with the speaker, the opposite phase sound of the second noise generated in the unmanned flying object and reaching the output region. This is because, if the timing is not synchronized, the noise cannot be reduced or only the opposite phase sound from the speaker is transmitted to the output region, and the opposite phase noise becomes noise to the contrary. On the other hand, according to this aspect, because the reaching time of the second noise reaching the output region is calculated, sound is output from the speaker on the basis of the opposite phase signal according to the reaching time. Therefore, the noise can be accurately reduced according to the arrival of the second noise at the output region. 
     Preferably, in the control apparatus of the present disclosure, the one or more unmanned flying objects include two or more unmanned flying objects, and the operations further include: calculating the second noises and the reaching time of the second noises for each of the two or more unmanned flying objects; generating the opposite phase signals with respect to the calculated second noises for each of the two or more unmanned flying objects; superimposing the opposite phase signals generated for each of the two or more unmanned flying objects; and causing the speaker to output the sound on a basis of a signal obtained by the superimposing. 
     The noises respectively generated from the two or more unmanned flying objects and reaching the output region respectively reach the output region. Therefore, the opposite phase signals with respect to the noises are superimposed. The speaker outputs sound based on a signal obtained by the superimposition. Consequently, the noises can be accurately reduced in the output region. 
     Preferably, in the control apparatus of the present disclosure, the noise information includes a magnitude of the first noises, and the operations further include: calculating a magnitude of the second noises using the position information and the magnitude of the first noises; and causing the speaker to output the sound on the basis of the generated opposite phase signals having a magnitude corresponding to the calculated magnitude of the second noises. 
     For example, the magnitude (the amplitude) of the first noise generated from the unmanned flying object changes according to space propagation before the first noise reaches the output region. For example, the amplitude of the noise decreases according to propagation attenuation. Therefore, the opposite phase signal for outputting the opposite phase sound having magnitude corresponding to the magnitude of the second noise reaching the output region is generated. Consequently, the noise can be accurately reduced in the output region. 
     Preferably, in the control apparatus of the present disclosure, the noise information includes a frequency of the first noises, and the operations further include: calculating a frequency of the second noises using the position information and the frequency of the first noises; and generating the opposite phase signals having a frequency corresponding to the calculated frequency of the second noises. 
     For example, the frequency of the first noise generated from the unmanned flying object changes according to space propagation before the first noise reaches the output region. For example, the frequency of the noise changes according to the movement of the unmanned flying object. Therefore, the opposite phase signal for outputting the opposite phase sound having the frequency of the second noise reaching the output region is generated. Consequently, the noise can be accurately reduced in the output region. 
     Preferably, in the control apparatus of the present disclosure, the operations further include: acquiring identification information of specific sounds output from one or more second speakers included in the one or more unmanned flying objects; detecting, using the acquired identification information, a signal corresponding to the specific sounds from a signal output from a microphone disposed in the output region; and causing the speaker to output the sound on the basis of the generated opposite phase signals when the signal corresponding to the specific sounds is detected. 
     The noise (undesired sound) and the specific sound propagate in the space at equal sound speed. Therefore, the first noise generated at the same timing as timing when the specific sound is output from the speaker of the unmanned flying object reaches the output region at the same timing as timing when the specific sound reaches the output region. Therefore, when the signal corresponding to the specific sound is detected (in other words, the timing when the specific sound reaches the output region), sound is output from the speaker disposed around the output region on the basis of the opposite phase signal. Consequently, the noise can be accurately reduced in the output region. 
     Preferably, in the control apparatus of the present disclosure, the operations further include calculating, using the detected signal corresponding to the specific sounds and the noise information, the second noises that reach the output region. 
     Consequently, influence on the first noise generated from the unmanned flying object due to space propagation before the noise reaches the output region can be predicted from influence on the specific sound due to space propagation before the specific sound reaches the output region. Therefore, the second noise reaching the output region can be more accurately calculated. 
     A control system according to an aspect of the present disclosure is a control system including: the above-described control apparatus; and the speaker that outputs the sound to the output region. 
     Consequently, the range in which undesired sound can be reduced can be expanded. Further, the weight on board of the unmanned flying object can also be reduced. 
     A control method according to an aspect of the present disclosure is a control method including: acquiring, by a computer, position information of one or more unmanned flying objects and noise information concerning first noises generated by the one or more unmanned flying objects; acquiring, by the computer, output region information indicating an output region of sound output from a speaker; calculating, by the computer, using the position information, the output region information, and the noise information, second noises reaching the output region, with the second noises being caused by the first noises which are generated by the one or more unmanned flying objects; generating, by the computer, opposite phase signals for outputting opposite phase sounds with respect to the calculated second noises; and causing, by the computer, the speaker to output sound on a basis of the generated opposite phase signals. 
     Consequently, the range in which undesired sound can be reduced can be expanded. Further, the weight on board of the unmanned flying object can also be reduced. 
     It should be note that these comprehensive and specific aspects may be realized by a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM or may be realized by any combination of the system, the apparatus, the method, the integrated circuit, the computer program, and the recording medium. 
     Embodiments are specifically explained below with reference to the drawings. Note that all of the embodiments explained below indicate comprehensive or specific examples. Numerical values, shapes, materials, components, disposed positions and connection forms of the components, steps, order of the steps, and the like described in the embodiments below are example and are not meant to limit the claims. Among the components in the embodiments, components not described in the independent claims indicating a highest order concept are explained as optional components. 
     Figures used in the following explanation are schematic diagrams and do not always strictly illustrate disposition, sizes, and the like of the components. 
     First Embodiment 
     A first embodiment is explained below with reference to  FIGS. 1 to 3 . 
       FIG. 1  is a diagram schematically illustrating the configurations of a control system  1  and an unmanned flying object  20  in the first embodiment. 
     The unmanned flying object  20  includes, for example, a body control unit  21 , a noise-information acquiring unit  22 , a time managing unit  23 , and a communication unit  24 . 
     The body control unit  21  is a processing unit that controls flight of the unmanned flying object  20 . The body control unit  21  includes a GPS (Global Positioning System) or the like for acquiring position information of the unmanned flying object  20  necessary for the control of the flight. 
     The noise-information acquiring unit  22  acquires noise information concerning first noise generated from the unmanned flying object  20 . For example, the noise information includes the magnitude and the frequency of the first noise generated from the unmanned flying object  20 . Note that the noise information may include the phase of the first noise. For example, the noise-information acquiring unit  22  acquires noise information including the amplitude (in other words, sound pressure) and the frequency of noise generated from the unmanned flying object  20  collected by a microphone mounted on the unmanned flying object  20 . Note that the noise-information acquiring unit  22  may acquire information such as rotating speed of a rotor blades included in the unmanned flying object  20 , rotating speed of a motor, and a control command to the unmanned flying object  20  and acquire noise information concerning the first noise specified from these kinds of information. This is because these kinds of information are information correlated to the first noise generated from the unmanned flying object  20  and noise information concerning the first noise generated from the unmanned flying object  20  can be predicted from these kinds of information. 
     For example, as the rotating speed of the rotor blade (the rotating speed of the motor) increases, the amplitude of noise (wind noise) generated by the rotor blade increases and the frequency of the noise increases. Therefore, for example, by measuring, in advance, noise generated from the rotor blade at each rotating speed of the rotor blade, the rotating speed of the rotor blade and noise information concerning undesired sound generated from the rotor blade can be modeled in advance. 
     The control command includes a command involving rotation of the rotor blade for, for example, ascending and descending the unmanned flying object  20 , moving the unmanned flying object  20  to the front and the rear and the left and the right, and turning the unmanned flying object  20 . The control command includes a moving route or speed information in future. Therefore, it is possible to predict from the control command how the rotating speed of the rotor blade fluctuates in future. That is, the control command (a predicted value of the rotating speed of the rotor blade) and noise information concerning undesired sound generated from the rotor blade can be modeled in advance. 
     The time managing unit  23  has a function of managing time synchronized with the control system  1 . That is, time managed in the time managing unit  23  and time managed in the control system  1  indicate the same time each other. The time managing unit  23  acquires time information indicating time at timing when the body control unit  21  acquires position information of the unmanned flying object  20  and time at timing when the noise-information acquiring unit  22  acquires noise information. Note that, for time synchronization of a plurality of systems, a time synchronizing function included in the GPS may be used or a time management server may be set in the control system  1  and a time synchronizing function such as an NTP (Network Time Protocol) may be used. 
     The communication unit  24  is, for example, a communication interface including an antenna and a transmission and reception circuit for a wireless signal. For example, information is transmitted from the unmanned flying object  20  to the control system  1  (a control apparatus  10  explained below) via the communication unit  24 . The communication unit  24  transmits the position information of the unmanned flying object  20  acquired by the body control unit  21 , the noise information acquired by the noise-information acquiring unit  22 , and the time information acquired by the time managing unit  23  to the control system  1 . 
     The control system  1  includes a control apparatus  10  and one or more speakers  30  that output sounds to an output region A 1 . The control system  1  includes three speakers  30  disposed to surround the output region A 1 . Note that the number of the speakers  30  to be disposed is not limited to three and may be any number if the number is one or more. The output region A 1  is a region to which the sounds from the speakers  30  are output and is a region where noises (second noises explained below) generated from one or more unmanned flying objects  20  and reaching the region are reduced. For example, the output region A 1  is a region on the ground but may be, for example, a region in the air. 
     The control apparatus  10  is an apparatus for reducing, in the output region A 1  of the sounds output from the speakers  30 , noises generated from the one or more unmanned flying objects  20  and reaching the output region A 1 . The configuration of the control apparatus  10  is explained with reference to  FIG. 2  as well. 
       FIG. 2  is a flowchart illustrating an example of the operation of the control apparatus  10  in the first embodiment. 
     The control apparatus  10  includes a first acquiring unit  11 , a second acquiring unit  12 , a calculating unit  13 , a signal generating unit  14 , an output control unit  15 , a communication unit  16 , and a storing unit  17 . The control apparatus  10  is, for example, an apparatus including a processor (a microprocessor), a memory (the storing unit  17 ), and a communication circuit (the communication unit  16 ). The communication unit  16  may include an antenna. Note that a memory other than the storing unit  17  may be included in the memory. The memory (the storing unit  17 ) is a ROM, a RAM, or the like and can store a control program to be executed by the processor. The first acquiring unit  11 , the second acquiring unit  12 , the calculating unit  13 , the signal generating unit  14 , and the output control unit  15  are realized by the processor that executes the control program stored in the memory in the control apparatus  10 . 
     The first acquiring unit  11  acquires position information of the one or more unmanned flying objects  20  and noise information concerning the first noise generated from one or more unmanned flying objects  20  (step S 11 ). For example, the first acquiring unit  11  acquires position information and noise information received by the communication unit  16  communicating with the communication unit  24  of the unmanned flying object  20 . At this time, the first acquiring unit  11  further acquires time information indicating generation time of the first noise (time when the noise-information acquiring unit  22  acquires the noise information). 
     The second acquiring unit  12  acquires output region information indicating the output region A 1  of sounds output from the speakers  30  (step S 12 ). The output region information specifically includes position information, range information, and the like of the output region A 1 . For example, the output region information is stored in the storing unit  17  in advance. Note that the communication unit  16  may receive output region information from an external terminal or the like and store the output region information in the storing unit  17  or update the output region information stored in the storing unit  17 . 
     The calculating unit  13  calculates, using the position information, the output region information, and the noise information, second noises reaching the output region A 1  in the first noises generated from the one or more unmanned flying objects  20  (step S 13 ). The magnitude (the amplitude) of sound is attenuated according to a distance from a generation source of the sound. An amount of the attenuation can be more easily derived by an experiment or the like or by a publicly-known method or the like. The position of the generation source of the first noise is the position of the unmanned flying object  20  as well. Therefore, the position of the generation source of the first noise is included in the position information of the unmanned flying object  20 . A distance from the generation source of the first noise is calculated from the position of the unmanned flying object  20 , the position of the output region A 1  included in the output region information, and the like. The magnitude of the first noise in the generation source of the first noise is included in the noise information. Therefore, the calculating unit  13  can calculate how much the magnitude (the amplitude) of the first noise (i.e., noise in the position of the unmanned flying object  20 ) included in the noise information is attenuated before the first noise reaches the output region A 1 , that is, can calculate the second noise generated from the unmanned flying object  20  and reaching the output region A 1 . Note that the calculating unit  13  may calculate how much the frequency of the first noise included in the noise information changes before the first noise reaches the output region A 1 . The calculating unit  13  may calculate a phase of the second noise at a point in time when the second noise reaches the output region A 1 . For example, a change in the phase of noise is caused by a multipath or the like that occurs, for example, when the noise reflects on an object. Presence or absence or a degree of the change of the phase may be calculated from characteristics (e.g., presence or absence of buildings and heights of the buildings) on a route from the position of the unmanned flying object  20  to the output region A 1 . Map information and the like may be stored in the storing unit  17  and the like. The calculating unit  13  may calculate the second noise reaching the output region A 1  considering the influence (reflection, etc.) of an obstacle or the like present around the output region A 1  and the unmanned flying object  20 . 
     The calculating unit  13  calculates, from the position information, the output region information, and the time information, a reaching time of the second noise reaching the output region A 1 . The reaching time of the second noise can be calculated from generation time of the first noise, the distance between the generation source of the first noise and the output region A 1 , and sound speed in the air. The generation time of the first noise is included in the time information. The distance between the generation source of the first noise and the output region A 1  is calculated from the position of the unmanned flying object  20 , the position of the output region A 1 , and the like. The sound speed in the air is substantially a fixed value of approximately 340 m/s. Therefore, the calculating unit  13  can calculate the reaching time of the second noise reaching the output region A 1 . 
     The signal generating unit  14  generates an opposite phase signal for outputting opposite phase sound with respect to the second noise calculated by the calculating unit  13  (step S 14 ). That is, the signal generating unit  14  generates an opposite phase signal for reducing, rather than the first noise generated from the unmanned flying object  20 , the second noise that is, for example, attenuated by space propagation before reaching the output region A 1 . The opposite phase signal is a signal obtained by inverting the amplitude or the like of the second noise calculated by the calculating unit  13 . 
     The output control unit  15  causes the speakers  30  to output sounds on the basis of the opposite phase signal generated by the signal generating unit  14  (step S 15 ). For example, because the reaching time of the second noise reaching the output region A 1  is calculated by the calculating unit  13 , the output control unit  15  causes the speakers  30  to output the sounds on the basis of the generated opposite phase signal according to the reaching time. The speakers  30  output the sounds toward the output region A 1 . The sounds are acoustic waves having an opposite phase of the phase of the second noise generated from the unmanned flying object  20  and reaching the output region A 1 . Therefore, the noise can be reduced in the output region A 1 . 
     Note that, in  FIG. 1 , one unmanned flying object  20  is illustrated as the one or more unmanned flying objects  20 . However, the one or more unmanned flying objects  20  may be two or more unmanned flying objects  20 . In this case, the first acquiring unit  11  acquires position information of each of the two or more unmanned flying objects  20  and noise information of each of the two or more unmanned flying objects  20 . The calculating unit  13  calculates, concerning each of the two or more unmanned flying objects  20 , the second noise using the position information, the noise information, and the output region information. The calculating unit  13  calculates a reaching time of the second noise concerning each of the two or more unmanned flying objects  20 . 
     At this time, the signal generating unit  14  generates each of opposite phase signals with respect to each of the calculated second noises and superimposes each of the opposite phase signals according to the calculated reaching time of the second noise. For example, the signal generating unit  14  sets superimposing timing according to reaching times of the noises and superimposes the noises that reach the set timing. The output control unit  15  causes the speakers  30  to output sounds on the basis of the superimposed signals. 
     In the explanation referring to  FIG. 1 , the unmanned flying object  20  directly communicates with the control apparatus  10  not via a repeater or the like. However, the unmanned flying object  20  may communicate via the repeater or the like. This is explained with reference to  FIG. 3 . 
       FIG. 3  is a diagram schematically illustrating the configurations of the control system  1 , the unmanned flying object  20 , and a control center  40  in a modification of the first embodiment. This modification is different from the explanation referring to  FIG. 1  in that the control apparatus  10  and the unmanned flying object  20  wirelessly communicate via the control center  40 . Otherwise, this modification is the same as the explanation referring to  FIG. 1 . Therefore, explanation of the similarities is omitted. The difference is mainly explained. 
     The control center  40  is, for example, a computer that performs management, operation, and the like of the unmanned flying object  20 . The control center  40  is capable of wirelessly communicating with the unmanned flying object  20 . The control center  40  is capable of communicating with the control apparatus  10  by wire or by radio. For example, the control center  40  generates a control command and transmits the control command to the unmanned flying object  20 . The body control unit  21  of the unmanned flying object  20  controls flight of the unmanned flying object  20  on the basis of the control command. 
     The communication unit  24  transmits the position information of the unmanned flying object  20  acquired by the body control unit  21 , the noise information acquired by the noise-information acquiring unit  22 , and the time information acquired by the time managing unit  23  to the control center  40 . The control center  40  receives these kinds of information and transmits the information to the communication unit  16  of the control apparatus  10 . 
     For example, when the noise-information acquiring unit  22  acquires a control command to the unmanned flying object  20  and acquires noise information concerning the first noise estimated from the control command, because the control command is generated by the control center  40 , the control center  40  can estimate the noise information by itself and may not receive the noise information from the unmanned flying object  20 . That is, in this case, the unmanned flying object  20  may not include the noise-information acquiring unit  22 . When the control center  40  has a function of observing the position of the unmanned flying object  20 , the control center  40  may not receive the noise information from the unmanned flying object  20 . That is, in this case, the unmanned flying object  20  may not include the GPS. In such a case, the control center  40  can transmit the control command to the unmanned flying object  20  and, at the same time, transmit the position information and the control command (the noise information) to the control apparatus  10  without waiting for the position information and the control command (the noise information) to be received from the unmanned flying object  20 . Therefore, an opposite phase signal can be generated beforehand. A processing delay and the like do not need to be considered. 
     As explained above, the control apparatus  10  includes the first acquiring unit  11  that acquires the position information of the one or more unmanned flying objects  20  and the noise information concerning the first noises generated from the one or more unmanned flying objects  20 , the second acquiring unit  12  that acquires the output region information indicating the output region A 1  of the sounds output from the speakers  30 , the calculating unit  13  that calculates, using the position information, the output region information, and the noise information, the second noises reaching the output region A 1  in the first noises generated from the one or more unmanned flying objects  20 , the signal generating unit  14  that generates the opposite phase signals for outputting the opposite phase sounds with respect to the calculated second noises, and the output control unit  15  that causes the speakers  30  to output the sounds on the basis of the generated opposite phase signals. 
     The first noise generated from the unmanned flying object  20  is, for example, attenuated and reflected by space propagation before reaching the output region A 1  and, in the output region A 1 , changes compared with the time of the generation in the unmanned flying object  20 . Therefore, when the output region A 1  of the sounds output from the speakers  30  and the generation source of the first noise are apart from each other, simply by generating the signal having the opposite phase of the phase of the first noise that is, for example, not attenuated at the time of the generation in the unmanned flying object  20 , even if the sounds are output from the speakers  30  on the basis of the signal, the noise cannot be accurately reduced in the output region A 1 . On the other hand, according to the present disclosure, the second noise generated from the unmanned flying object  20  and reaching the output region A 1 , that is, noise changing from the first noise at the time of the generation in the unmanned flying object  20  is calculated. Therefore, the speakers  30  can be disposed in the periphery of the output region A 1 , which is a region where noise is desired to be reduced such as the ground away from the unmanned flying object  20 . Therefore, the speakers  30  may not be mounted on the unmanned flying object  20 . A weight on board of the unmanned flying object  20  can be reduced. When the speakers  30  are not mounted on the unmanned flying object  20 , there is no limit in the weight and the like of the speakers  30 . Therefore, the speakers  30  can be increased in size in order to improve the performance of the speakers  30 . A plurality of speakers  30  can be used. Consequently, a range in which undesired sound can be reduce can be expanded. 
     The first acquiring unit  11  may further acquire time information indicating generation time of the first noise. The calculating unit  13  may calculate, from the position information, the output region information, and the time information, a reaching time of the second noise reaching the output region A 1 . The output control unit  15  may cause the speakers  30  to output sounds on the basis of the generated opposite phase signal according to the calculated reaching time. 
     Timing when opposite phase sound of the second noise generated in the unmanned flying object  20  and reaching the output region A 1  is output by the speakers  30  is desirably synchronized with arrival of the noise. This is because, if the timing is not synchronized, the noise cannot be reduced or only the opposite phase sound from the speakers  30  is transmitted to the output region A 1  and the opposite phase noise becomes noise to the contrary. On the other hand, according to this embodiment, because the reaching time of the second noise reaching the output region A 1  is calculated, sounds are output from the speakers  30  on the basis of the opposite phase signal according to the reaching time. Therefore, the noise can be accurately reduced according to the arrival of the second noise at the output region A 1 . 
     The one or more unmanned flying objects  20  may be two or more unmanned flying objects  20 . The calculating unit  13  may calculate the second noise and the reaching time of the second noise concerning each of the two or more unmanned flying objects  20 . The signal generating unit  14  may generate each of opposite phase signals with respect to each of the calculated second noises and superimpose each of the opposite phase signals according to each of the calculated reaching times of the second noises. The output control unit  15  may cause the speakers  30  to output sounds on the basis of a signal obtained by the superimposition. 
     Noises respectively generated from the two or more unmanned flying objects  20  and reaching the output region A 1  respectively reach the output region A 1 . Therefore, the opposite phase signals with respect to the noises are superimposed and the speakers  30  output the sounds based on the signal obtained by the superimposition. Consequently, the noises can be accurately reduced in the output region A 1 . 
     The noise information may include the magnitude of the first noise. The calculating unit  13  may calculate the magnitude of the second noise from the position information and the magnitude of the first noise. The output control unit  15  may cause the speakers  30  to output sounds based on the opposite phase signal having magnitude corresponding to the calculated magnitude of the second noise. 
     For example, the magnitude (the amplitude) of the first noise generated from the unmanned flying object  20  changes according to space propagation before the first noise reaches the output region A 1 . For example, the amplitude of the noise decreases according to propagation attenuation. Therefore, the opposite phase signal for outputting the opposite phase sound having magnitude corresponding to the magnitude of the second noise reaching the output region A 1  is generated. Consequently, the noise can be accurately reduced in the output region A 1 . 
     The noise information may include the frequency of the first noise. The calculating unit  13  may calculate the frequency of the second noise from the position information and the frequency of the first noise. The signal generating unit  14  may generate the opposite phase signal having the calculate frequency of the second noise. 
     For example, the frequency of the first noise generated from the unmanned flying object  20  changes according to space propagation before the first noise reaches the output region A 1 . For example, the frequency of the noise changes according to the movement of the unmanned flying object  20 . Therefore, the opposite phase signal for outputting the opposite phase sound having the frequency of the second noise reaching the output region A 1  is generated. Consequently, the noise can be accurately reduced in the output region A 1 . 
     The control system  1  includes the control apparatus  10  and the speakers  30  that output sounds to the output region A 1 . 
     Consequently, the range in which undesired sound can be reduced can be expanded. Further, the weight on board of the unmanned flying object  20  can be reduced. 
     Second Embodiment 
     A second embodiment is explained with reference to  FIG. 4 . 
       FIG. 4  is a diagram schematically illustrating the configurations of a control system  1   a  and an unmanned flying object  20   a  in the second embodiment. 
     The unmanned flying object  20   a  is different from the unmanned flying object  20  in the first embodiment in that the unmanned flying object  20   a  does not include the time managing unit  23  and includes a speaker  25 . Otherwise, the unmanned flying object  20   a  is the same as the unmanned flying object  20  in the first embodiment. Therefore, the difference is mainly explained. 
     The unmanned flying object  20   a  includes the speaker  25  that outputs specific sound. The specific sound includes identification information. For example, in a system that includes a microphone and recognizes identification information in advance, when the identification information can be detected from sound collected by the microphone, it can be recognized that the specific sound is included in the collected sound. 
     The unmanned flying object  20   a  outputs the specific sound from the speaker  25 . The communication unit  16  transmits position information, noise information, and identification information to the control system  1   a.    
     The control system  1   a  is different from the control system  1  in the first embodiment in that the control system  1   a  includes a control apparatus  10   a  instead of the control apparatus  10  and includes a microphone  50 . The control apparatus  10   a  is different from the control apparatus  10  in the first embodiment in that the control apparatus  10   a  further includes a signal detecting unit  18 . Otherwise, the control system  1   a  and the control apparatus  10   a  are the same as the control system  1  and the control apparatus  10  in the first embodiment. Therefore, the difference is mainly explained below. 
     The microphone  50  is disposed in the output region A 1  and is capable of collecting sound propagated to the output region A 1 . Note that a plurality of microphones  50  may be disposed according to the size of the output region A 1 . The microphone  50  converts the collected sound into an electric signal and outputs the electric signal to the signal detecting unit  18 . 
     The first acquiring unit  11  further acquires identification information of specific sounds respectively output from speakers  25  of one or more unmanned flying objects  20   a . For example, the first acquiring unit  11  acquires identification information received by the communication unit  16  communicating with the communication unit  24  of the unmanned flying object  20   a . Note that the identification information may be stored in advance in, for example, the storing unit  17 . The first acquiring unit  11  may acquire the identification information from the storing unit  17  or the like. 
     The signal detecting unit  18  detects, using the identification information acquired by the first acquiring unit  11 , a signal corresponding to the specific sound from the signal output from the microphone  50  disposed in the output region A 1 . The control apparatus  10   a  has acquired the identification information. When the identification information is successfully detected from the sound collected by the microphone  50  as explained above, the control apparatus  10   a  can recognize that the specific sound is included in the collected sound. Consequently, the control apparatus  10   a  can recognize that the specific sound output from the speaker  25  of the unmanned flying object  20   a  reaches the output region A 1 , that is, can recognize that noise generated from the unmanned flying object  20   a  at timing when the specific sound is output also reaches the output region A 1 . 
     When the signal corresponding to the specific sound is detected, the output control unit  15  causes the speakers  30  to output sounds on the basis of an opposite phase signal generated by the signal generating unit  14 . In the second embodiment, the unmanned flying object  20   a  does not include the time managing unit  23 . A reaching time of the second noise reaching the output region A 1  is not calculated by the calculating unit  13 . However, time when the signal corresponding to the specific sound corresponds to the reaching time. Therefore, the output control unit  15  causes the speakers  30  to output sounds on the basis of the opposite phase signal according to the time when the signal corresponding to the specific sound is detected. The speakers  30  output the sounds toward the output region A 1 . As explained in the first embodiment, the sounds are acoustic waves having the opposite phase of the phase of the second noise generated from the unmanned flying object  20   a  and reaching the output region A 1 . Therefore, the noise can be reduced in the output region A 1 . 
     Note that the calculating unit  13  may calculate the second noise reaching the output region A 1  using the detected signal corresponding to the specific sound and the noise information. Specifically, the specific sound is, for example, attenuated by space propagation before reaching the output region A 1 . Sound information including the amplitude and the frequency of the specific sound changes in the output region A 1  compared with when the specific sound is generated in the unmanned flying object  20   a . The signal corresponding to the specific sound detected by the signal detecting unit  18  includes the sound information after the change by the space propagation. Therefore, influence due to the space propagation can be estimated by comparing the sound information of the specific sound when being output from the speaker  25  of the unmanned flying object  20   a  and the sound information after the change by the space propagation. The influence is exerted on the first noise generated from the unmanned flying object  20   a  before the first noise reaches the output region A 1 . Therefore, the second noise reaching the output region A 1  can be more accurately calculated from the estimated influence. 
     Note that the calculating unit  13  can calculate, without using the position information, the second noise reaching the output region A 1  according to the estimated influence. That is, when the calculating unit  13  does not use the position information, the unmanned flying object  20   a  may not include a GPS or the like. 
     As in the modification of the first embodiment, the control apparatus  10   a  and the unmanned flying object  20   a  may perform wireless communication via the control center  40 . 
     As explained above, the control apparatus  10   a  may further include the signal detecting unit  18 . The first acquiring unit  11  may further acquire the identification information of the specific sounds respectively output from the speakers  25  included in the one or more unmanned flying objects  20   a . The signal detecting unit  18  may detect, using the acquired identification information, the signal corresponding to the specific sound from the signal output from the microphone  50  disposed in the output region A 1 . The output control unit  15  may cause the speakers  30  to output sounds on the basis of the generated opposite phase signal when the signal corresponding to the specific sound is detected. 
     Both of the noise (undesired sound) and the specific sound are propagated in the space at equal sound speed. Therefore, the first noise generated at the same timing as timing when the specific sound is output from the speaker  25  of the unmanned flying object  20   a  reaches the output region A 1  at the same timing as timing when the specific sound reaches the output region A 1 . Therefore, when the signal corresponding to the specific sound is detected (in other words, at the timing when the specific sound reaches the output region A 1 ), sounds are output from the speakers  30  disposed around the output region A 1  on the basis of the opposite phase signal. Consequently, noise can be surely reduced in the output region A 1 . 
     The calculating unit  13  may calculate the second noise reaching the output region A 1  using the detected signal corresponding to the specific sound and the noise information. 
     Influence on the first noise generated from the unmanned flying object  20   a  due to space propagation before the noise reaches the output region A 1  can be predicted from influence on the specific sound due to space propagation before the specific sound reaches the output region A 1 . Therefore, the second noise reaching the output region A 1  can be more accurately calculated. 
     Other Embodiments 
     The control apparatus and the control system of the present disclosure are explained above on the basis of the embodiments. However, the present disclosure is not limited to the embodiments. Various modifications conceived by those skilled in the art applied to the embodiments and forms constructed by combining constituent elements in different embodiments are also included in the scope of the present disclosure as long as the modifications and the forms do not deviate from the gist of the present disclosure. 
     For example, the control apparatuses  10  and  10   a  may be realized by a server apparatus or the like. The functional components included in the control apparatuses  10  and  10   a  may be distributed and disposed in a plurality of server apparatuses. 
     For example, in the embodiments, the first acquiring unit  11  acquires the time information. However, the first acquiring unit  11  may not acquire the time information. This is because, for example, when a communication delay in the wireless communication between the control apparatus  10  and the unmanned flying object  20  is fixed, generation time of the noise information can be calculated from time when the first acquiring unit  11  acquires the noise information and the like. 
     The present disclosure not only can be realized as the control apparatus and the control system but also can be realized as an information processing method including steps (processing) performed by the components configuring the control apparatus and the control system. 
     Specifically, as illustrated in  FIG. 2 , the control method includes acquiring, using a computer, the position information of the one or more unmanned flying objects  20  and the noise information concerning the first noises generated from the one or more unmanned flying objects  20  (step S 11 ), acquiring the output region information indicating the output region A 1  of the sounds output from the speakers  30  (step S 12 ), calculating, using the position information, the output region information, and the noise information, the second noises reaching the output region A 1  in the first noises generated from the one or more unmanned flying objects  20  (step S 13 ), generating the opposite phase signal for outputting the opposite phase sound with respect to the calculated second noises (step S 14 ), and causing the speakers  30  to output sounds on the basis of the generated opposite phase signal (step S 15 ). 
     For example, the steps may be executed by a computer (a computer system). The present disclosure can be realized as a computer program for causing the computer to execute the steps included in the method. Further, the present disclosure can be realized as a non-transitory computer-readable recording medium such as a CD-ROM having the computer program recorded therein. 
     For example, when the present disclosure is realized by the computer program (software), the computer program is executed using hardware resources such as a CPU, a memory, and an input/output circuit of the computer, whereby the steps are executed. That is, the CPU acquires data from the memory, the input/output circuit, or the like and performs an arithmetic operation and outputs an arithmetic operation result to the memory, the input/output circuit, or the like, whereby the steps are executed. 
     A plurality of components included in the control apparatus and the control system in the embodiments may be respectively realized as dedicated or general-purpose circuits. The components may be realized as one circuit or may be realized as a plurality of circuits. 
     The plurality of components included in the control apparatus and the control system in the embodiments may be realized as an LSI (Large Scale Integration), which is an integrated circuit (IC). The components may be individually integrated into one chip or may be integrated into one chip to include a part or all of the components. The LSI is sometimes called system LSI, super LSI, or ultra LSI according to a difference in a degree of integration. 
     The integrated circuit is not limited to the LSI and may be realized by a dedicated circuit or a general-purpose processor. A programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor capable of reconfiguring connection and setting of circuit cells inside the LSI may be used. 
     Further, if a technique for circuit integration replacing the LSI emerges according to the progress of the semiconductor technique or another technique deriving from the semiconductor technique, naturally, circuit integration of the components included in the control apparatus and the control system may be performed using the technique. 
     Besides, forms obtained by applying various modifications conceived by those skilled in the art to the embodiments and forms realized by optionally combining the components and the functions in the embodiments within a range not departing from the gist of the present disclosure are also included in the present disclosure. 
     An aspect of the present disclosure can be used in, for example, a system for reducing noise generated from an unmanned flying object.