Abstract:
The present invention is to provide a wireless aircraft, a method of cancelling noise, and a program for the wireless aircraft, which are capable of maintaining the flight performance of the aircraft and decreasing noises. The wireless aircraft  10  having a motor and a propeller, in which the motor rotates the propeller, collects a motor-rotating sound from the motor and generates an antiphase sound wave against the collected motor-rotating sound, collects a marginal sound, and cancels noise by synthesizing the antiphase sound wave against the collected motor-rotating sound with the collected motor-rotating sound.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to Japanese Patent Application No. 2015-128437 filed on Jun. 26, 2015, the entire contents of which are incorporated by reference herein. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a wireless aircraft having a motor and a propeller, in which the motor rotates the propeller, a method of cancelling noise, and a program for the wireless aircraft. 
       BACKGROUND ART 
       [0003]    Recently, wireless aircrafts having a motor and a propeller, in which the motor rotates the propeller, have been put to practical use. Such wireless aircrafts collect sounds while flying in the air. 
         [0004]    Such wireless aircrafts collect undesired sounds such as motor-rotating sounds generated by rotating the propeller while flying in the air. In other words, the motor-rotating sounds mingle in the collected sounds as noises. 
         [0005]    Although differing from wireless aircrafts, a method of decreasing noises other than desired sounds has been disclosed, in which antiphase sound waves against the noises are generated to decrease the noises (refer to Patent Document 1). 
       CITATION LIST 
     Patent Literature 
       [0006]    Patent Document 1: JP 2012-118334 A 
       SUMMARY OF INVENTION 
       [0007]    According to Patent Document 1, ambient noises are collected, and antiphase sound waves against the collected ambient noises are generated and output from a first speaker to a predetermined space. In addition, antiphase sound waves against sounds collected from a speaker which is different from the first speaker are generated and output from a second speaker to a microphone. As a result, the collected ambient noises can be decreased. 
         [0008]    However, the method described in Patent Document 1 requires two or more speakers to decrease noises. This increases not only the cost but also the weight of the device to decrease the flight performance. 
         [0009]    The inventor has found that noises generated by a motor can be decreased by synthesizing antiphase sound waves against the noises. 
         [0010]    An objective of the present invention is to provide a wireless aircraft, a method of cancelling noise, and a program for the wireless aircraft, which are capable of maintaining the flight performance of the aircraft and decreasing noises. 
         [0011]    According to the first aspect of the present invention, a wireless aircraft having a motor and a propeller, the motor rotating the propeller, includes: 
         [0012]    an antiphase sound wave generation unit that collects a motor-rotating sound from the motor and that generates an antiphase sound wave against the collected motor-rotating sound; 
         [0013]    a microphone unit that collects a marginal sound; and 
         [0014]    a noise cancellation unit cancels noise by synthesizing the antiphase sound wave against the collected motor-rotating sound with the marginal sound collected by the microphone unit. 
         [0015]    According to the first aspect of the present invention, a wireless aircraft having a motor and a propeller, the motor rotating the propeller collects a motor-rotating sound from the motor and generates an antiphase sound wave against the collected motor-rotating sound, collects a marginal sound, and cancels noise by synthesizing the antiphase sound wave against the collected motor-rotating sound with the collected motor-rotating sound. 
         [0016]    The first aspect of the invention belongs to the category of a wireless aircraft but has the same working effects under different categories such as a method of cancelling noise and a program for a wireless aircraft. 
         [0017]    According to the second aspect of the present invention, in the wireless aircraft according to the first aspect of the present invention, the antiphase sound wave generation unit generates an antiphase sound wave against a previously stored motor-rotating sound. 
         [0018]    According to the second aspect of the present invention, the wireless aircraft according to the first aspect of the present invention generates an antiphase sound wave against a previously stored motor-rotating sound. 
         [0019]    According to the third aspect of the present invention, a method of cancelling noise executed by a wireless aircraft having a motor and a propeller, the motor rotating the propeller includes the steps of: 
         [0020]    collecting a motor-rotating sound from the motor and generating an antiphase sound wave against the collected motor-rotating sound; 
         [0021]    collecting a marginal sound; and 
         [0022]    cancelling noise by synthesizing the antiphase sound wave against the collected motor-rotating sound with the marginal sound collected by the microphone unit. 
         [0023]    According to the fourth aspect, a computer program product for use in a wireless aircraft having a motor and a propeller, the motor rotating the propeller, comprising a non-transitory computer usable medium having a set of instructions physically embodied therein, the set of instructions including computer readable program code, which when executed by the wireless aircraft causes the information processing unit to: 
         [0024]    collect a motor-rotating sound from the motor and generate an antiphase sound wave against the collected motor-rotating sound; 
         [0025]    collect a marginal sound; and 
         [0026]    cancel noise by synthesizing the antiphase sound wave against the collected motor-rotating sound with the marginal sound collected by the microphone unit. 
         [0027]    The present invention is to provide a wireless aircraft, a method of cancelling noise, and a program for the wireless aircraft, which are capable of maintaining the flight performance of the aircraft and decreasing noises. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0028]      FIG. 1  is the conceptual diagram of the wireless aircraft  10  according to the first embodiment. 
           [0029]      FIG. 2  is the conceptual diagram of the wireless aircraft  10  according to the second embodiment. 
           [0030]      FIG. 3  is the functional block diagram of the wireless aircraft  10 . 
           [0031]      FIG. 4  is a flow chart showing the noise cancellation process executed by the wireless aircraft  10  according to the first embodiment. 
           [0032]      FIG. 5  is a flow chart showing the noise cancellation process executed by the wireless aircraft  10  according to the second embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0033]    Hereinafter, a preferable mode of the present invention will be described below with reference to the accompanying drawings. However, this is illustrative only, and the scope of the present invention is not limited thereto. 
       Wireless Aircraft  10  According to First Embodiment 
       [0034]    The present invention according to the first embodiment will be explained with reference to  FIG. 1 . The wireless aircraft  10  includes a microphone unit  100 , an antiphase sound wave generation unit  110 , and a communication unit  120 . The wireless aircraft  10  is an uninhabited airborne vehicle that is remotely controllable from an external terminal such as an operation terminal or computer and that is automatically controllable based on a predetermined action programmed inside the vehicle itself. The wireless aircraft  10  flies in the air with a propeller rotated by a motor. 
         [0035]    The wireless aircraft  10  collects a marginal sound from the microphone unit  100  to be described later by using the microphone unit  100 . The microphone unit  100  collects a sound from a sound source  200  and a motor sound source  300 . The sound from the sound source  200  comes from a place specified based on a remote request or a predetermined programmed action. The sound from the motor sound source  300  comes from a motor rotating a propeller of the wireless aircraft  10 . 
         [0036]    The microphone unit  100  includes a device collecting the sound from the sound source  200  and a device collecting the sound from the motor sound source  300  based on a remote request or a predetermined programmed action. The communication unit  120  includes a device transmitting and receiving short-range wireless communication signals and radio waves in a prescribed band. 
         [0037]    First, the wireless aircraft  10  collects a sound from the sound source  200  by using the microphone unit  100  based on a remote request or a predetermined programmed action (step S 01 ). 
         [0038]    At the same time, the wireless aircraft  10  also collects a motor-rotating sound from the motor sound source  300  by using the microphone unit  100  (step S 02 ). 
         [0039]    The wireless aircraft  10  analyzes the motor-rotating sound collected from the motor in the step S 02  by using the antiphase sound wave generation unit  110 , generates an antiphase sound wave against the analyzed motor-rotating sound, and outputs the antiphase sound wave to the microphone unit  100  (step S 03 ). 
         [0040]    The wireless aircraft  10  synthesizes the sound collected from the sound source  200  in the step S 01  with the antiphase sound wave generated in the step S 03  to perform noise cancellation (step S 04 ). In the step S 04 , since the sound collected from the sound source  200  is synthesized with the antiphase sound wave against the motor-rotating sound, the motor-rotating sound mingling in the sound from the sound source  200  can be cancelled. 
         [0041]    The wireless aircraft  10  transmits the sound data after performing the noise cancellation in the step S 04  to an external terminal by using the communication unit  120  (step S 05 ). 
       Wireless Aircraft  10  According to Second Embodiment 
       [0042]    The present invention according to the second embodiment will be explained with reference to  FIG. 2 . The wireless aircraft  10  includes a microphone unit  100 , an antiphase sound wave generation unit  110 , a communication unit  120 , and a motor sound memory unit  130 . The wireless aircraft  10  is an uninhabited airborne vehicle that is remotely controllable from an external terminal such as an operation terminal or computer and that is automatically controllable based on a predetermined action programmed inside the vehicle itself. The wireless aircraft  10  flies in the air with a propeller rotated by a motor. 
         [0043]    The wireless aircraft  10  collects a marginal sound from the microphone unit  100  to be described later by using the microphone unit  100 . The microphone unit  100  collects a sound from a sound source  200  and a motor sound source  300 . The sound from the sound source  200  comes from a place specified by a remote request or a predetermined programmed action. The sound from the motor sound source  300  comes from a motor rotating a propeller of the wireless aircraft  10 . 
         [0044]    The microphone unit  100  includes a device collecting the sound from the sound source  200  and a device collecting the sound from the motor sound source  300  based on a remote request or a predetermined programmed action. The communication unit  120  includes a device transmitting and receiving short-range wireless communication signals and radio waves in a prescribed band. The motor sound memory unit  130  includes a device storing the sound collected from the motor sound source  300 . 
         [0045]    First, the wireless aircraft  10  collects a motor-rotating sound from the motor sound source  300  by using the microphone unit  100  (step S 10 ). In the step S 10 , the microphone unit  100  collects a motor-rotating sound from a motor rotating a propeller as the sound from the motor sound source  300 . 
         [0046]    The wireless aircraft  10  stores the sound collected from the motor sound source  300  in the step S 10  by using the motor sound memory unit  130  (step S 11 ). 
         [0047]    Then, the wireless aircraft  10  collects a sound from the sound source  200  by using the microphone unit  100  (step S 12 ). 
         [0048]    The wireless aircraft  10  obtains the motor-rotating sound stored in the step S 11  by using the antiphase sound wave generation unit  110  (step S 13 ), generates an antiphase sound wave against the obtained motor-rotating sound, and outputs the generated antiphase sound wave to the microphone unit  100  (step S 14 ). 
         [0049]    The wireless aircraft  10  synthesizes the sound collected from the sound source  200  in the step S 12  with the antiphase sound wave generated in the step S 14  to perform noise cancellation (step S 15 ). In the step S 15 , since the sound collected from the sound source  200  is synthesized with the antiphase sound wave against the motor-rotating sound, the motor-rotating sound mingling in the sound from the sound source  200  can be cancelled. 
         [0050]    The wireless aircraft  10  transmits the sound data after performing the noise cancellation in the step S 15  to an external terminal by using the communication unit  120  (step S 16 ). 
       Functions 
       [0051]    The configuration of the wireless aircraft  10  will be explained with reference to  FIG. 3 . The wireless aircraft  10  has the function described below to fly in the air with a propeller rotated by a motor and collect a marginal sound by using a microphone, etc. 
         [0052]    The wireless aircraft  10  is provided with a control unit  11  including a central processing unit (hereinafter referred to as “CPU”), a random access memory (hereinafter referred to as “RAM”), and a read only memory (hereinafter referred to as “ROM”); and a communication unit  12  including a Wi-Fi® enabled device complying with, for example, IEEE 802.11, a short-range wireless communication device such as an infrared communication device, and a device for transmitting and receiving radio wave in a predetermined band. 
         [0053]    The wireless aircraft  10  also includes a memory unit  13  such as a hard disk, a semiconductor memory, a recording medium, or a memory card for storing data. The memory unit  13  stores the motor-rotating sound from the wireless aircraft  10  to be described later. The wireless aircraft  10  also includes a generation unit  14  such as a device generating an antiphase sound wave against the motor-rotating sound to be described later. The wireless aircraft  10  also includes a sound collection unit  15  such as a microphone device collecting a marginal sound. 
         [0054]    In the wireless aircraft  10 , the control unit  11  reads a predetermined program and runs a data transmission module  20  in cooperation with the communication unit  12 . Furthermore, the control unit  11  reads a predetermined program and runs a motor sound storing module  30  in cooperation with the memory unit  13 . Still furthermore, the control unit  11  reads a predetermined program and runs an antiphase sound wave generation module  40  in cooperation with the generation unit  14 . Yet still furthermore, the control unit  11  reads a predetermined program and runs a sound collection module  50  in cooperation with the sound collection unit  15 . 
       Noise Cancellation Process in First Embodiment 
       [0055]      FIG. 4  is a flow chart showing the noise cancellation process executed by the wireless aircraft  10  according to the first embodiment. The tasks executed by the modules will be described below with this process. 
         [0056]    First, the sound collection module  50  determines whether or not the module has received a request of sound collection (step S 20 ). In the step S 20 , the sound collection module  50  determines whether or not the module has received a request of sound collection from an external terminal such as an operation terminal or computer. 
         [0057]    In the step S 20 , if determining that the sound collection module  50  has not received a request of sound collection (NO), the sound collection module  50  repeats this determination process until receiving the request. 
         [0058]    If determining that the sound collection module  50  has received a request of sound collection (YES) in the step S 20 , the sound collection module  50  starts to collect a marginal sound (step S 21 ). In the step S 21 , when starting to collect a marginal sound, the sound collection module  50  may also start to take images such as still or moving images around the wireless aircraft. In this case, when stopping collecting a marginal sound, the sound collection module  50  only has to stop taking the images. 
         [0059]    At the same time, the sound collection module  50  collects a motor-rotating sound from a motor rotating a propeller (step S 22 ). 
         [0060]    The antiphase sound wave generation module  40  analyzes the motor-rotating sound collected by the sound collection module  50  and generates an antiphase sound wave against the analyzed sound (step S 23 ). 
         [0061]    The antiphase sound wave generation module  40  outputs the generated antiphase sound wave to around a microphone (step S 24 ). 
         [0062]    The sound collection module  50  synthesizes the sound wave of the collected marginal sound with the antiphase sound wave generated in the step S 23  (step S 25 ), eliminates the motor-rotating sound from the collected marginal sound, and generates sound data (step S 26 ). 
         [0063]    The data transmission module  20  transmits the sound data generated in the step S 26  to the external terminal (step S 27 ). 
         [0064]    The sound collection module  50  determines whether or not the module has received a request of end-of-sound collection (step S 28 ). In the step S 28 , the sound collection module  50  determines whether or not the module has received a request of end-of-sound collection from an external terminal. In the step S 28 , the wireless aircraft  10  may generate a request of end-of-sound collection based on a previously set program, etc., in the case, for example, where a predetermined time has passed since sound collection is started or where the wireless aircraft has moved a predetermined distance since sound collection is started. 
         [0065]    In the step S 28 , if determining that the sound collection module  50  has not received a request of end-of-sound collection (NO), the sound collection module  50  repeats the steps from S 22  to S 27 . 
         [0066]    If determining that the sound collection module  50  has received a request of end-of-sound collection (YES) in the step S 28 , the sound collection module  50  stops collecting any sounds (step S 29 ) 
       Noise Cancellation Process in Second Embodiment 
       [0067]      FIG. 5  is a flow chart showing the noise cancellation process executed by the wireless aircraft  10  according to the second embodiment. The tasks executed by the modules will be described below with this process. 
         [0068]    First, the sound collection module  50  collects a sound from a motor rotating a propeller (step S 30 ). 
         [0069]    The motor sound storing module  30  stores the collected motor-rotating sound (step S 31 ). 
         [0070]    The antiphase sound wave generation module  40  analyzes the stored motor-rotating sound and generates an antiphase sound wave against the analyzed sound (step S 32 ). 
         [0071]    Then, the sound collection module  50  determines whether or not the module has received a request of sound collection (step S 33 ). In the step S 33 , the sound collection module  50  determines whether or not the module has received a request of sound collection from an external terminal such as an operation terminal or computer. 
         [0072]    In the step S 33 , if determining that the sound collection module  50  has not received a request of sound collection (NO), the sound collection module  50  repeats this determination process until receiving the request. 
         [0073]    If determining that the sound collection module  50  has received a request of sound collection (YES) in the step S 33 , the sound collection module  50  starts to collect a marginal sound (step S 34 ). In the step S 34 , when starting to collect a marginal sound, the sound collection module  50  may also start to take images such as still or moving images around the wireless aircraft. In this case, when stopping collecting a marginal sound, the sound collection module  50  only has to stop taking the images. 
         [0074]    The antiphase sound wave generation module  40  outputs the antiphase sound wave generated in the step S 32  to around a microphone (step S 35 ). 
         [0075]    The sound collection module  50  synthesizes the sound wave of the collected marginal sound with the antiphase sound wave generated in the step S 32  (step S 36 ), eliminates the motor-rotating sound from the collected marginal sound, and generates sound data (step S 37 ). 
         [0076]    The data transmission module  20  transmits the sound data generated in the step S 37  to the external terminal (step S 38 ). 
         [0077]    The sound collection module  50  determines whether or not the module has received a request of end-of-sound collection (step S 39 ). In the step S 39 , the sound collection module  50  determines whether or not the module has received a request of end-of-sound collection from an external terminal. In the step S 39 , the wireless aircraft  10  may generate a request of end-of-sound collection based on a previously set program, etc., in the case, for example, where a predetermined time has passed since sound collection is started or where the wireless aircraft has moved a predetermined distance since sound collection is started. 
         [0078]    In the step S 39 , if determining that the sound collection module  50  has not received a request of end-of-sound collection (NO), the sound collection module  50  repeats the steps from S 35  to S 38 . 
         [0079]    If determining that the sound collection module  50  has received a request of end-of-sound collection (YES) in the step S 39 , the sound collection module  50  stops collecting any sounds (step S 40 ). 
         [0080]    To achieve the means and the functions that are described above, a computer (including CPU, an information processor, and various terminals) reads and executes a predetermined program. For example, the program is provided in the form recorded in a computer-readable medium such as a flexible disk, CD (e.g. CD-ROM), and DVD (e.g. DVD-ROM, DVD-RAM). In this case, a computer reads a program from the recording medium, forwards and stores the program to and in an internal or an external storage, and executes it. The program may be previously recorded in, for example, a storage (recording medium) such as a magnetic disk, an optical disk, and a magnetic optical disk and provided from the storage to a computer through a communication line. 
         [0081]    The embodiments of the present invention are described above. However, the present invention is not limited to the above-mentioned embodiments. The effects described in the embodiments of the present invention are only the most preferable effect produced from the present invention. The effects of the present invention are not limited to those described in the embodiments of the present invention. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               10  Wireless aircraft