Patent Publication Number: US-2021167848-A1

Title: Control method, unmanned aerial vehicle, and remote control device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of patent application Ser. No. 16/518,955, filed on Jul. 22, 2019, which is a continuation of International Application No. PCT/CN2017/072265, filed on Jan. 23, 2017, the entire contents of both of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the technology field of consumer electronics and, more particularly, to a control method, an unmanned aerial vehicle, and a remote control device. 
     BACKGROUND 
     Radio frequency signals of an unmanned aerial vehicle (“UAV”) and a remote control device may be transmitted at the maximum power, such that good transmission of image signals and control signals at a long distance can be maintained. However, it may be a waste of energy when the flight is at a short distance. In the meantime, maintaining the maximum transmission power for a long time period may bring relatively large electromagnetic radiation effects to human bodies located adjacent to a remote control device, and bring large interferences to the surrounding electromagnetic environment. 
     SUMMARY 
     In accordance with an aspect of the present disclosure, there is provided a method for controlling a signal transmission power of at least one of an unmanned aerial vehicle (“UAV”) or a remote control device. The method includes determining whether a remote control distance between the UAV and the remote control device increases or decreases. The method also includes increasing or maintaining a signal transmission power of at least one of the UAV or the remote control device if the remote control distance increases. The method further includes decreasing or maintaining the signal transmission power of at least one of the UAV or the remote control device if the remote control distance decreases. 
     In accordance with another aspect of the present disclosure, there is provided an unmanned aerial vehicle (“UAV”). The UAV includes a processor configured to determine whether a remote control distance between the UAV and a remote control device increases or decreases. The UAV also includes a transmitter configured to increase or maintain a signal transmission power of at least one of the UAV or the remote control device if the remote control distance increases. The transmitter is also configured to decrease or maintain the signal transmission power of at least one of the UAV or the remote control device if the remote control distance decreases. 
     In accordance with another aspect of the present disclosure, there is provided a remote control device. The remote control device includes a processor configured to determine whether a remote control distance between an unmanned aerial vehicle (“UAV”) and the remote control device increases or decreases. The remote control device also includes a transmitter configured to increase or maintain a signal transmission power of at least one of the UAV or the remote control device if the remote control distance increases. The transmitter is also configured to decrease or maintain the signal transmission power of at least one of the UAV or the remote control device if the remote control distance decreases. 
     According to the control method, UAV, and remote control device of the present disclosure, when a remote control distance between the UAV and the remote control device increases, the UAV and/or the remote control device may be controlled to increase or maintain a signal transmission power respectively. When the remote control distance between the UAV and the remote control device decreases, the UAV and/or the remote control device may be controlled to decrease or maintain the signal transmission power, respectively. As such, the transmission power of the UAV and the remote control device may be reduced while maintaining the normal signal transmission between the UAV and the remote control device. On the one hand, energy may be saved for the UAV and the remote control device, avoiding waste. On the other hand, maintaining the maximum power to transmit signals at all time can be avoided, thereby reducing the electromagnetic radiation effects of the transmission power on human bodies located adjacent to the remote control device, as well as reducing interference with the surrounding electromagnetic environment. 
     Additional aspects and advantages of the technical solutions of the present disclosure will be partially provided in the following descriptions, and partially become obvious from the following descriptions. Alternatively, the additional aspects and advantages of the technical solutions can be understood from practicing the various embodiments of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To better describe the technical solutions of the various embodiments of the present disclosure, the accompanying drawings showing the various embodiments will be briefly described. As a person of ordinary skill in the art would appreciate, the drawings show only some embodiments of the present disclosure. Without departing from the scope of the present disclosure, those having ordinary skills in the art could derive other embodiments and drawings based on the disclosed drawings without inventive efforts. 
         FIG. 1  is a flow chart illustrating a control method, according to an example embodiment. 
         FIG. 2  is a schematic diagram of functional modules of the UAV and the remote control device, according to an example embodiment. 
         FIG. 3  is a flow chart illustrating a control method, according to another example embodiment. 
         FIG. 4  is a schematic diagram of functional modules of the UAV and the remote control device, according to another example embodiment. 
         FIG. 5  is a flow chart illustrating a control method, according to another example embodiment. 
         FIG. 6  is a schematic diagram of functional modules of the UAV, according to an example embodiment. 
         FIG. 7  is a schematic diagram of functional modules of the remote control device, according to an example embodiment. 
         FIG. 8  is a schematic diagram of functional modules of the UAV and the remote control device, according to another example embodiment. 
         FIG. 9  is a flow chart illustrating a control method, according to another example embodiment. 
         FIG. 10  is a flow chart illustrating a control method, according to another example embodiment. 
         FIG. 11  is a schematic diagram of functional modules of the UAV and the remote control device, according to another example embodiment. 
         FIG. 12  is a flow chart illustrating a control method, according to another example embodiment. 
         FIG. 13  is a flow chart illustrating a control method, according to another example embodiment. 
         FIG. 14  is a flow chart illustrating a control method, according to another example embodiment. 
     
    
    
       
     
       
         
           
               
             
               
                   
               
               
                 List of Major Elements: 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Unmanned aerial vehicle 
                 100 
               
               
                   
                 First processor 
                 10 
               
               
                   
                 First transmitter 
                 12 
               
               
                   
                 First distance detector 
                 14 
               
               
                   
                 Global positioning system 
                 142 
               
               
                   
                 Barometer 
                 144 
               
               
                   
                 First calculator 
                 146 
               
               
                   
                 First storage device 
                 16 
               
               
                   
                 First signal receiver 
                 18 
               
               
                   
                 Remote control device 
                 200 
               
               
                   
                 Second processor 
                 20 
               
               
                   
                 Second transmitter 
                 22 
               
               
                   
                 Distance detector 
                 24 
               
               
                   
                 Horizontal distance acquisition module 
                 242 
               
               
                   
                 Height acquisition module 
                 244 
               
               
                   
                 Second calculator 
                 246 
               
               
                   
                 Second storage device 
                 26 
               
               
                   
                 Second signal receiver 
                 28 
               
               
                   
                   
               
            
           
         
       
     
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Next, the embodiments of the present disclosure will be described in detail. Illustrations of the embodiments are shown in the accompanying drawings. The same or similar reference numerals indicate the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are illustrative, are used to explain the present disclosure, and should not be understood as limiting the present disclosure. 
     It should be understood that in the present disclosure, relational terms such as “first,” “second” are only used for descriptive purposes only, and should not be understood as indicating or implying relative importance or implicitly indicating the quantity of the referenced technical features. As such, a feature modified by the “first” or “second” may indicate or implicitly include one or more such features. In the descriptions of the present disclosure, “multiple” means two or more than two, unless expressly specified otherwise. 
     As used herein, when a first component (or unit, element, member, part, piece) is referred to as “coupled,” “mounted,” “fixed,” “secured” to or with a second component, it is intended that the first component may be directly coupled, mounted, fixed, or secured to or with the second component, or may be indirectly coupled, mounted, or fixed to or with the second component via another intermediate component. The terms “coupled,” “mounted,” “fixed,” and “secured” do not necessarily imply that a first component is permanently coupled with a second component. The first component may be detachably coupled with the second component when these terms are used. When a first component is referred to as “connected” to or with a second component, it is intended that the first component may be directly connected to or with the second component or may be indirectly connected to or with the second component via an intermediate component. The connection may include mechanical and/or electrical connections. The connection may be permanent or detachable. The electrical connection may be wired or wireless. When a first component is referred to as “disposed,” “located,” or “provided” on a second component, the first component may be directly disposed, located, or provided on the second component or may be indirectly disposed, located, or provided on the second component via an intermediate component. When a first component is referred to as “disposed,” “located,” or “provided” in a second component, the first component may be partially or entirely disposed, located, or provided in, inside, or within the second component. The terms “perpendicular,” “horizontal,” “vertical,” “left,” “right,” “up,” “upward,” “upwardly,” “down,” “downward,” “downwardly,” and similar expressions used herein are merely intended for describing relative positional relationship. 
     In addition, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context indicates otherwise. The terms “comprise,” “comprising,” “include,” and the like specify the presence of stated features, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups. The term “and/or” used herein includes any suitable combination of one or more related items listed. For example, A and/or B can mean A only, A and B, and B only. The term “and/or” may be interpreted as “at least one of” the related items. For example, A and/or B may be interpreted as at least one of A or B, such as A, B, or A and B. The symbol “/” means “or” between the related items separated by the symbol. The phrase “at least one of A, B, or C” encompasses all combinations of A, B, and C, such as A only, B only, C only, A and B, B and C, A and C, and A, B, and C. In this regard, A and/or B can mean at least one of A or B. The term “module” as used herein includes hardware components or devices, such as circuit, housing, sensor, connector, etc. The term “communicatively couple(d)” or “communicatively connect(ed)” indicates that related items are coupled or connected through a communication channel, such as a wired or wireless communication channel. The term “unit,” “sub-unit,” or “module” may encompass a hardware component, a software component, or a combination thereof. For example, a “unit,” “sub-unit,” or “module” may include a processor, a portion of a processor, an algorithm, a portion of an algorithm, a circuit, a portion of a circuit, etc. 
     Further, when an embodiment illustrated in a drawing shows a single element, it is understood that the embodiment may include a plurality of such elements. Likewise, when an embodiment illustrated in a drawing shows a plurality of such elements, it is understood that the embodiment may include only one such element. The number of elements illustrated in the drawing is for illustration purposes only, and should not be construed as limiting the scope of the embodiment. Moreover, unless otherwise noted, the embodiments shown in the drawings are not mutually exclusive, and they may be combined in any suitable manner. For example, elements shown in one embodiment but not another embodiment may nevertheless be included in the other embodiment. 
     The following descriptions provide various different embodiments or examples for realizing the different structures of the present disclosure. To simplify the description of the present disclosure, components and configurations of specified examples are described. They are only examples and are not intended to limit the scope of the present disclosure. In addition, various embodiments of the present disclosure may use repeated reference numbers and/or reference alphabets. Such repetition is for the purpose of simplification and clarity, and does not indicate any relationship between the various embodiments and/or configurations. Further, the present disclosure provides examples of various processes and materials. A person having ordinary skills in the art can recognize that other processes and/or other materials may be used. 
     Next, the various embodiments of the present disclosure will be described. The illustrations of the various embodiments are shown in the accompanying drawings. The same or similar reference numerals indicate the same or similar components or components having the same or similar functions. The embodiments described below with reference to the drawings are illustrative only, are used to explain the present disclosure, and should not be understood to limit the scope of the present disclosure. 
     As shown in  FIG. 1  and  FIG. 2 , a control method of the present disclosure may be used to control a signal transmission power of a UAV  100  and/or a remote control device  200 . The control method may include the following steps: 
     S 1 : determining whether a remote control distance D between the UAV  100  and the remote control device  200  increases or decreased; 
     S 2 : when the remote control distance D increases, increasing or maintaining a signal transmission power of the UAV  100  and/or the remote control device  200 ; and 
     S 3 : when the remote control distance D decreases, decreasing or maintaining the signal transmission power of the UAV  100  and/or the remote control device  200 . 
     In some embodiments, determining whether the remote control distance D between the UAV  100  and the remote control device  200  increases or decreases may be judged directly based on the distance between the UAV  100  and the remote control device  200 . For example, the distance between the UAV  100  and the remote control device  200  may be calculated through a distance detector. In some embodiments, determining whether the remote control distance D between the UAV  100  and the remote control device  200  increases or decreases may be judged from a parameter that can indirectly reflect a distance change between the UAV  100  and the remote control device  200 . For example, when the distance between the UAV  100  and the remote control device  200  increases, a signal-to-noise ratio of a signal transmitted between the UAV  100  and the remote control device  200  decreases; when the distance between the UAV  100  and the remote control device  200  decreases, the signal-to-noise ratio of the signal transmitted between the UAV  100  and the remote control device  200  increases. As such, the signal-to-noise ratio of the signal received by the UAV and the remote control device  200  may be used as a parameter that reflects whether the distance between the UAV  100  and the remote control device  200  increases or decreases. 
     Referring to  FIG. 2 , the control method may be executed by the UAV  100 . In some embodiments, the UAV  100  may include a first processor  10  and a first transmitter  12 . The first processor  10  may be configured to execute step S 1 , and the first transmitter  12  may be configured to execute steps S 2  and S 3 . The first processor  10  and the first transmitter  12  may be electrically connected. The first processor  10  may be configured to control the first transmitter  12  to change a transmission power. In other words, the first processor  10  may be configured to determine whether the remote control distance D between the UAV  100  and the remote control device  200  increases or decreases. The first transmitter  12  may be configured to increase or maintain the signal transmission power of the UAV  100  and/or the remote control device  200  when the remote control distance D increases. The first transmitter  12  may also be configured to decrease or maintain the signal transmission power of the UAV  100  and/or the remote control device  200  when the remote control distance D decreases. 
     Referring to  FIG. 2 , the control method may be executed by the remote control device  200 . In some embodiments, the remote control device  200  may include a second processor  20  and a second transmitter  22 . The second processor  20  may be configured to execute step S 1 , and the second transmitter  22  may be configured to execute steps S 2  and S 3 . The second processor  20  and the second transmitter  22  may be electrically connected. The second processor  20  may be configured to control the second transmitter  22  to change transmission power. In other words, the second processor  20  may be configured to determine whether the remote control distance D between the UAV  100  and the remote control device  200  increases or decreases. The second transmitter  22  may be configured to increase or maintain the signal transmission power of the UAV  100  and/or the remote control device  200  when the remote control distance D increases. The second transmitter  22  may also be configured to decrease or maintain the signal transmission power of the UAV  100  and/or the remote control device  200  when the remote control distance D decreases. In some embodiments, the remote control device  200  may include any one of terminals having a control function, such as a cell phone, a remote controller, a smart watch, smart glasses, or a smart helmet. 
     In some embodiments, the control method, UAV  100 , and the remote control device  200  may be configured to: when the remote control distance D between the UAV  100  and the remote control device  200  increases, controlling the UAV  100  and/or the remote control device  200  to increase or maintain the signal transmission power respectively; when the remote control distance D between the UAV  100  and the remote control device  200  decreases, controlling the UAV  100  and/or the remote control device  200  to decrease or maintain the signal transmission power respectively. As such, the transmission power of the UAV  100  and/or the remote control device  200  may be reduced while maintaining the normal signal transmission between the UAV  100  and the remote control device  200 . On the one hand, energy may be saved for the UAV  100  and the remote control device  200 , avoiding waste. On the other hand, maintaining the maximum power to transmit signals at all time can be avoided, thereby reducing the electromagnetic radiation effects of the transmission power on human bodies located adjacent to the remote control device  200 , as well as reducing interference with the surrounding electromagnetic environment. 
     Referring to  FIG. 3 , in some embodiments, the control method may also include the following steps: 
     S 4 : detecting a remote control distance D between the UAV  100  and the remote control device  200 . In some embodiments, the remote control distance between the UAV  100  and the remote control device  200  is a spatial straight distance between the UAV  100  and the remote control device  200 . In some embodiments, the control method may first execute step S 4 , and then execute step S 1  and step S 2  or S 3 . 
     Referring to  FIG. 4 , the control method may be executed by the UAV  100 . In some embodiments, the UAV  100  may include a first distance detector  14  configured to execute step S 4 . In other words, the first distance detector  14  may be configured to measure or detect the remote control distance D between the UAV  100  and the remote control device  200 . The first distance detector  14  and the first processor  10  may be electrically connected. The remote control distance D between the UAV  100  and the remote control device  200  obtained by the first distance detector  14  may be transmitted to the first processor  10 . 
     In some embodiments, the control method may be executed by the remote control device  200 . The remote control device  200  may include a second distance detector  24  configured to execute step S 4 . In other words, the second distance detector  24  may be configured to detect the remote control distance D between the UAV  100  and the remote control device  200 . The second distance detector  24  and the second processor  20  may be electrically connected. The remote control distance between the UAV  100  and the remote control device  200  obtained by the second distance detector  24  may be transmitted to the second processor  20 . 
     In some embodiments, the first distance detector  14  and the second distance detector  24  may be distance sensors, respectively. In some embodiments, the first distance detector  14  and the second distance detector  24  may both be single component, such as an infrared distance sensor, an ultrasonic distance sensor, a time of flight (“TOF”) distance sensor, etc. The remote control distance D between the UAV  100  and the remote control device  200  may be obtained or detected directly through the above distance sensor. In other embodiments, the first distance detector  14  and the second distance detector  24  may each include multiple components, such as a global positioning system, a barometer, and a processor. The remote control distance D between the UAV  100  and the remote control device  200  may be obtained through the multiple components. In some embodiments, the remote control distance D may be obtained through other methods. For example, the UAV  100  may transmit a time signal to the remote control device  200 , such as 9:00. The second distance detector  24  may receive the time signal, obtain a time at which the time signal is received, such as 9:05, and calculate a difference between the two time instances (e.g., 5 minutes), and calculate the remote control distance D between the UAV  100  and the remote control device  200  based on a signal transmission speed. In some embodiments, the first distance detector  14  may obtain the remote control distance D through the same method. 
     As such, the UAV  100  and the remote control device  200  may directly detect the distance between the UAV  100  and the remote control device  200  through the first distance detector  14  and the second distance detector  24 , respectively. 
     In some embodiments, the UAV  100  and the remote control device  200  may respectively detect the distance between them through the first distance detector  14  and the second distance detector  24 , respectively. Thus, the UAV  100  and the remote control device  200  may respectively change the transmission power of the UAV  100  and/or the remote control device  200  based on the distance detected by the UAV  100  and the remote control device  200 , respectively. 
     Referring to  FIG. 5 , in some embodiments, step S 4 , i.e., the step of detecting the remote control distance D between the UAV  100  and the remote control device  200  may include: 
     S 41 : obtaining a horizontal distance of the UAV  100  relative to the remote control device  200 ; 
     S 42 : obtaining a height of the UAV  100  relative to the remote control device  200 ; and 
     S 43 : calculating the remote control distance D based on the horizontal distance and the height. 
     In some embodiments, the sequence for executing the steps S 41  and S 42  is not limited. For example, steps S 41  and S 42  may be executed simultaneously. Alternatively, step S 41  may be executed before or after step S 42 , and step S 43  may be executed after execution of steps S 41  and S 42  are completed. 
     Referring to  FIG. 6 , the control method may be executed by UAV  100 . In some embodiments, the first distance detector  14  of the UAV  100  may include a global positioning system  142 , a barometer  144 , and a first calculator  146 . The global positioning system  142 , the barometer  144 , and the first calculator  146  may be configured to execute steps S 41 , S 42 , and S 43 , respectively. In other words, the global positioning system  142  may be configured to obtain a horizontal distance of the UAV  100  relative to the remote control device  200 . The barometer  144  may be configured to obtain a height of the UAV  100  relative to the remote control device  200 . The first calculator  146  may be configured to calculate the remote control distance D based on the horizontal distance and the height. The global positioning system  142  and the barometer  144  may both be electrically connected with the first calculator  146 . The data obtained by the global positioning system  142  and the barometer  144  may both be transmitted to the first calculator  146  for processing. In some embodiments, the global positioning system  142  may include, but not be limited to, any one of the Global Positioning System (“GPS”) of the United States, the Global Navigation Satellite System (“GLONASS”) of Russia, the Beidou system of China, and the Galileo system of Europe. 
     Referring to  FIG. 7 , the control method may be executed by the remote control device  200 . In some embodiments, the second distance detector  24  of the remote control device  200  may include a horizontal distance acquisition module  242 , a height acquisition module  244 , and a second calculator  246 . The horizontal distance acquisition module  242 , the height acquisition module  244 , and the second calculator  246  may be configured to execute the steps S 41 , S 42 , and S 43 , respectively. In other words, the horizontal distance acquisition module  242  may be configured to obtain the horizontal distance of the UAV  100  relative to the remote control device  200 . The height acquisition module  244  may be configured to obtain the height of the UAV  100  relative to the remote control device  200 . The second calculator  246  may be configured to calculate the remote control distance D based on the horizontal distance and the height. The horizontal distance acquisition module  242  and the height acquisition module  244  may both be electrically connected with the second calculator  246 . Data obtained by the horizontal distance acquisition module  242  and the height acquisition module  244  may both be transmitted to the second calculator  246  for processing. The horizontal distance acquisition module  242  may include, but not be limited to, any one of the GPS, GLONASS, the Beidou system of China, and the Galileo system of Europe. The height acquisition module  244  may include, but not be limited to, the barometer. 
     As such, the remote control distance D between the UAV  100  and the remote control device  200  may be calculated based on the horizontal distance of the UAV  100  relative to the remote control device  200  and the height of the UAV  100  relative to the remote control device  200 . 
     Referring to  FIG. 8 , in some embodiments, the UAV  100  and the remote control device  200  may each include a first storage device  16  and a second storage device  26 . The first storage device  16  and the second storage device  26  may both be configured to store a pre-configured truth table (as shown in Table 1). The truth table may include a distance range and preset transmission power corresponding to the distance range. The step of increasing or maintaining the signal transmission power of the UAV and/or the remote control device (step S 2 ) may include controlling the UAV  100  and/or the remote control device  200  to execute the preset transmission power based on the remote control distance D and the distance range; and/or 
     The step of decreasing or maintaining the signal transmission power of the UAV  100  and/or the remote control device  200  (step S 3 ) may include controlling the UAV  100  and/or the remote control device  200  to execute the preset transmission power based on the remote control distance and the distance range. 
     Next descriptions explain the step of controlling the UAV  100  and/or the remote control device  200  to execute the preset transmission power based on the remote control distance D and the distance range: when the remote control distance D varies within a distance range in the truth table, the transmission power of the UAV  100  and the remote control device  200  may remain unchanged. For example, although the remote control distance D changes, if it remains in a range of (1, 2] km, then the transmission power of the UAV  100  may remain at 19 dBm (decibel-milliwatts), and the transmission power of the remote control device  200  remains at 19 dBm. When the remote control distance D increases from a distance range to another distance range in the truth table, e.g., when the remote control distance D increases from the range of (1, 2] to the range of (2, 3], the transmission power of the UAV  100  and the remote control device  200  may be increased. For example, the transmission power of the UAV  100  may be increased from 19 dBm to 22 dBm. The transmission power of the remote control device  200  may be increased from 19 dBm to 22 dBm. When the remote control distance D decreases from a distance range to another distance range in the truth table, e.g., when the remote control distance D decreases from the range of (1, 2] to the range of (0, 1], the transmission power of the UAV  100  and the remote control device  200  may be decreased. For example, the transmission power of the UAV  100  may be decreased from 19 dBm to 16 dBm, and the transmission power of the remote control device  200  may be decreased from 19 dBm to 16 dBm. In addition, the distance range and the preset transmission power in the truth table 1 may be obtained through practical external field test. In some embodiments, the truth table may be obtained through testing multiple different external field environments. For example, the external field environment may include: city environment, sea environment, mountain environment, plateau environment, etc. As such, the transmission power of the UAV  100  and the remote control device  200  in the truth table is relatively accurate. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Distance range 
                 Remote control device preset 
                 UAV preset transmission 
               
               
                 D (km) 
                 transmission power (dBm) 
                 power (dBm) 
               
               
                   
               
             
            
               
                 ≤1 
                 16 
                 16 
               
               
                 1 &lt; D ≤ 2 
                 19 
                 19 
               
               
                 2 &lt; D ≤ 3 
                 22 
                 22 
               
               
                 3 &lt; D ≤ 4 
                 25 
                 25 
               
               
                 4 &lt; D 
                 28 
                 28 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the first storage device  16  and the first processor  10  of the UAV  100  may be electrically connected. The first processor  10  may obtain the remote control distance D between the UAV  100  and the remote control device  200 , and may control the first transmitter  12  based on the truth table stored in the first storage device  16  to maintain or change the transmission power. The second storage device  26  and the second processor  20  of the remote control device  200  may be electrically connected. The second processor  20  may obtain the distance between the UAV  100  and the remote control device  200  and may control the second transmitter  22  based on the truth table stored in the second storage device  26  to maintain or change the transmission power. As such, the transmission power of the UAV  100  and the remote control device  200  may be reduced while maintaining the normal signal transmission between the UAV  100  and the remote control device  200 . On the one hand, energy may be saved for the UAV  100  and the remote control device  200 , avoiding waste. On the other hand, maintaining the maximum power to transmit signals at all time may be avoided, thereby reducing the electromagnetic radiation effects of the transmission power on human bodies located adjacent to the remote control device  200 , as well as reducing the interference with the surrounding electromagnetic environment. 
     Referring to  FIG. 9 , in some embodiments, three steps S 4 , S 1 , and S 2  or S 3  may be executed once every first predetermined time interval T 1 . In other words, three steps of detecting the distance between the UAV  100  and the remote control device  200 , determining whether the remote control distance D between the UAV  100  and the remote control device  200  increases or decreases, increasing or maintaining the signal transmission power of the UAV  100  and/or the remote control device  200 , or decreasing or maintaining the signal transmission power of the UAV  100  and/or the remote control device  200  may be executed once every first predetermined time interval T 1 . 
     Referring to  FIG. 6  and  FIG. 8 , the control method may be executed by the UAV  100 . In some embodiments, step S 4  executed by the first distance detector  14  of the UAV  100  (in some embodiments, step S 4  may include steps S 41 , S 42 , and S 43 ), step S 1  executed by the first processor  10 , and step S 2  or S 3  executed by the first transmitter  12  may be executed once every first predetermined time interval T 1 . 
     Referring to  FIG. 7  and  FIG. 8 , the control method may be executed by the remote control device  200 . In some embodiments, step S 4  executed by the second distance detector  24  of the remote control device  200  (in some embodiments, step S 4  may include steps S 41 , S 42 , and S 43 ), step S 1  executed by the second processor  20 , and step S 2  or S 3  executed by the second transmitter  22  may be executed once every first predetermined time interval T 1 . 
     As such, at every first predetermined time interval T 1 , the UAV  100  and the remote control device  200  may each detect the remote control distance D between the UAV  100  and the remote control device  200 . Accordingly, the transmission power of the UAV  100  and the remote control device  200  may be changed in real time based on the remote control distance D and the truth table and maintain the quality of the signal transmission between the UAV  100  and the remote control device  200 . 
     In some embodiments, the first predetermined time interval T 1  implemented in the control method, the UAV  100 , and the remote control device  200  may be any suitable value obtained from the range of (0.001-1) second. For example, the first predetermined time interval T 1  may be 0.001 second, 0.005 second, 0.01 second, 0.05 second, 0.1 second, 0.15 second, 0.2 second, 0.25 second, 0.3 second, 0.35 second, 0.4 second, 0.45 second, 0.5 second, 0.55 second, 0.6 second, 0.65 second, 0.7 second, 0.75 second, 0.8 second, 0.85 second, 0.9 second, 0.95 second, or 1 second. In some embodiments, value of the first predetermined time interval T 1  may be set based on a flight velocity of the UAV  100 . 
     Referring to  FIG. 10 , in some embodiments, step S 1 , i.e., determining whether the remote control distance D between the UAV  100  and the remote control device  200  increases or decreases may include the following steps: 
     S 11 : detecting a current signal-to-noise ratio St of a signal receiver of the UAV  100  and/or the remote control device  200 ; 
     S 12 : comparing the current signal-to-noise ratio St with a reference signal-to-noise ratio S 0 ; 
     S 13 : if the current signal-to-noise ratio St is smaller than the reference signal-to-noise ratio S 0 , determining that the remote control distance D increases; 
     S 14 : if the current signal-to-noise ratio St is greater than the reference signal-to-noise ratio S 0 , determining that the remote control distance D decreases. 
     In some embodiments, steps S 11 , S 12 , and S 13  or S 14  are executed in the listed order. In some embodiments, the reference signal-to-noise ratio S 0  may be determined through external field testing the UAV  100 . When the current signal-to-noise ratio St equals to the reference signal-to-noise ratio S 0 , images and control signals may be transmitted with a high quality without any interruptions or risk of data loss. In some embodiments, the reference signal-to-noise ratio S 0  may be obtained from a range of (−4 to −2) dB. For example, the reference signal-to-noise ratio S 0  may have a value of −4 dB, −3.9 dB, −3.8 dB, −3.75 dB, −3.6 dB, −3.5 dB, −3.4 dB, −3.3 dB, −3.25 dB, −3.2 dB, −3.1 dB, −3 dB, −2.9 dB, −2.8 dB, −2.75 dB, −2.7 dB, −2.6 dB, −2.5 dB, −2.4 dB, −2.3 dB, −2.25 dB, −2.2 dB, −2.1 dB, −2 dB. The value of the reference signal-to-noise ratio S 0  may be selected based on the flight velocity of the UAV  100 . In some embodiments, if the current signal-to-noise ratio St of the UAV  100  and the remote control device  200  equals to the reference signal-to-noise ratio S 0 , then normal signal transmission between the UAV  100  and the remote control device  200  may be maintained. If the current signal-to-noise ratio St is smaller than the reference signal-to-noise ratio S 0 , under the condition that the transmission power of the UAV  100  and the remote control device  200  remains unchanged, it may indicate that the quality of signal transmission between the UAV  100  and the remote control device  200  decreases and that the remote control distance D increases. If the current signal-to-noise ratio St is greater than the reference signal-to-noise ratio S 0 , under the condition that that the transmission power of the UAV  100  and the remote control device  200  remains unchanged, it may indicate that the quality of signal transmission between the UAV  100  and the remote control device  200  increases and that the remote control distance D decreases. 
     Referring to  FIG. 11 , the control method may be executed by the UAV  100 . In some embodiments, the UAV  100  may include a first signal receiver  18  electrically connected with the first processor  10 . The first processor  10  may be configured to execute steps S 11 , S 12 , S 13 , and S 14 . In other words, the first processor  10  may be configured to detect a current signal-to-noise ratio St of the first signal receiver  18  of the UAV  100 , and compare the current signal-to-noise ratio St with a reference signal-to-noise ratio S 0 . The first processor  10  may be configured to determine that the remote control distance D increases if the current signal-to-noise ratio St is smaller than the reference signal-to-noise ratio S 0 , and determine that the remote control distance D decreases if the current signal-to-noise ratio St is greater than the reference signal-to-noise ratio S 0 . 
     In some embodiments, the control method may be executed by the remote control device  200 . In some embodiments, the remote control device  200  may include a second signal receiver  28  electrically connected with the second processor  20 . The second processor  20  may be configured to execute steps S 11 , S 12 , S 13 , and S 14 . In other words, the second processor  20  may be configured to detect a current signal-to-noise ratio St of the second signal receiver  28  of the remote control device  200 , and compare the current signal-to-noise ratio St with a reference signal-to-noise ratio S 0 . The second processor  20  may be configured to determine that the remote control distance D increases if the current signal-to-noise ratio St is smaller than the reference signal-to-noise ratio S 0 , and determine that the remote control distance D decreases if the current signal-to-noise ratio St is greater than the reference signal-to-noise ratio S 0 . 
     Referring to  FIG. 12  and  FIG. 14 , in some embodiments, step S 2 , i.e., the step of increasing or maintaining the signal transmission power of the UAV  100  and/or the remote control device  200  when the remote control distance D increases (in some embodiments, it means the current signal-to-noise ratio St is smaller than the reference signal-to-noise ratio S 0 ) may include: 
     S 21 : adding a predetermined change value Pstep to a current signal transmission power of the UAV  100  and/or the remote control device  200  to obtain an updated signal transmission power, and maintaining an updated current signal-to-noise ratio St to be the reference signal-to-noise ratio S 0 . When the current signal-to-noise ratio St is the reference signal-to-noise ratio S 0 , images and control signals may be transmitted at a high quality. As such, when the current signal-to-noise ratio St of the UAV  100  and the remote control device  200  equals to the reference signal-to-noise ratio S 0 , signals can be transmitted normally at the remote control distance D between the UAV  100  and the remote control device  200 . 
     Referring to  FIG. 11 , the control method may be executed by the UAV  100 . In some embodiments, the first transmitter  12  of the UAV  100  may execute step S 21 . In other words, the predetermined change value Pstep may be added to the current signal transmission power of the UAV  100  to obtain an updated signal transmission power, and the updated current signal-to-noise ratio St may be maintained to be the reference signal-to-noise ratio S 0 . 
     In some embodiments, the control method may be executed by the remote control device  200 . In some embodiments, the second transmitter  22  of the remote control device  200  may be configured to execute step S 21 . In other words, the predetermined change value Pstep may be added to the current signal transmission power of the remote control device  200  to obtain an updated signal transmission power, and the updated current signal-to-noise ratio St may be maintained to be the reference signal-to-noise ratio S 0 . 
     Referring to  FIG. 13 , in some embodiments, step S 3 , i.e., the step of decreasing or maintaining the signal transmission power of the UAV  100  and/or the remote control device  200  when the remote control distance D decreases (in some embodiments, it indicates that the current signal-to-noise ratio St is greater than the reference signal-to-noise ratio S 0 ) may include: 
     S 31 : calculating a current difference S between the current signal-to-noise ratio St of the UAV  100  and/or the remote control device  200  and a reference signal-to-noise ratio S 0 ; 
     S 32 : compare the current difference S with a predetermined difference δS; 
     S 33 : if the current difference S is smaller than or equal to the predetermined difference δS, maintaining the current signal transmission power of the UAV  100  and/or the remote control device  200  unchanged; 
     S 34 : if the current difference S is greater than the predetermined difference δS, reducing the current signal transmission power of the UAV  100  and/or the remote control device  200  by a predetermined change value Pstep to obtain an updated signal transmission power, and maintaining an updated current signal-to-noise ratio St to be the reference signal-to-noise ratio S 0 . 
     In some embodiments, the predetermined difference δS is greater than 0 (δS&gt;0). If the current difference S is smaller than the predetermined difference δS, i.e., if the current signal-to-noise ratio St is greater than the reference signal-to-noise ratio S 0  and smaller than or equal to a sum of the reference signal-to-noise S 0  and the predetermined difference δS (i.e., S 0 &lt;St≤(S 0 +δS)), then the current signal transmission power of the UAV  100  and/or the remote control device  200  may be maintained unchanged. If the current difference S is greater than the predetermined difference δS, i.e., if the current signal-to-noise ratio St is greater than the sum of the reference signal-to-noise ratio S 0  and the predetermined difference δS (i.e., St&gt;(S 0 +δS)), the current signal transmission power of the UAV  100  and/or the remote control device  200  may be reduced by the predetermined change value Pstep to obtain an updated signal transmission power. As such, by setting the predetermined difference δS, instability of the transmission power caused by reducing the current signal transmission power of the UAV  100  and/or the remote control device  200  by the predetermined change value Pstep may be avoided. 
     Referring to  FIG. 11 , the control method may be executed by the UAV  100 . In some embodiments, the first transmitter  12  of the UAV  100  may be configured to execute steps S 31 , S 32 , S 33 , and S 34 . In other words, the first transmitter  12  may be configured to: 
     calculate a current difference S between the current signal-to-noise ratio St of the UAV  100  and the reference signal-to-noise ratio S 0 ; 
     compare the current difference S with a predetermined difference δS; 
     if the current difference S is smaller than or equal to the predetermined difference δS, control the UAV  100  to maintain the current signal transmission power of the UAV  100  unchanged; 
     if the current difference S is greater than the predetermined difference δS, control the UAV  100  to reduce the current signal transmission power of the UAV  100  by a predetermined change value Pstep to obtain an updated signal transmission power, and to maintain an updated current signal-to-noise ratio St to be the reference signal-to-noise ratio S 0 . 
     Referring to  FIG. 11 , the control method may be executed by the remote control device  200 . In some embodiments, the second transmitter  22  of the remote control device  200  may execute steps S 31 , S 32 , S 33 , and S 34 . In other words, the second transmitter  22  may be configured to: 
     calculate a current difference S between a current signal-to-noise ratio St of the remote control device  200  and a reference signal-to-noise ratio S 0 ; 
     compare the current difference S with a predetermined difference δS; 
     if the current difference S is smaller than or equal to the predetermined difference δS, control the remote control device  200  to maintain a current signal transmission power of the remote control device  200  unchanged; 
     if the current difference S is greater than the predetermined difference δS, control the remote control device  200  to reduce a current signal transmission power of the remote control device  200  by a predetermined change value Pstep to obtain an updated signal transmission power, and to maintain an updated current signal-to-noise ratio St to be the reference signal-to-noise ratio S 0 . 
     In some embodiments, after step S 1  (in some embodiments, step S 1  may include steps S 11 , S 12 , and S 13 ) is executed, steps S 21  or S 31 , step S 32  and step S 33  or S 34  may be executed. 
     As such, when the signal-to-noise ratio St received by the UAV  100  and the remote control device  200  is greater than the reference signal-to-noise ratio S 0 , i.e., when the remote control distance D between the UAV  100  and the remote control device  200  decreases, the signal transmission power of the UAV  100  and the remote control device  200  may be reduced, or the UAV  100  and the remote control device  200  may be controlled to maintain the signal transmission power. While the normal signal transmission between the UAV  100  and the remote control device  200  is maintained, on the one hand, energy may be saved for the UAV  100  and the remote control device  200 , avoiding waste. On the other hand, maintaining the maximum power to transmit signals at all the time may be avoided, thereby reducing electromagnetic radiation effects of the transmission power on human bodies located adjacent to the remote control device  200 , as well as reducing interference with the surrounding electromagnetic environment. 
     In some embodiments, the reference signal-to-noise ratio S 0  implemented in the control method, the UAV  100  and the remote control device  200  may be obtained through external field test. In some embodiments, the reference signal-to-noise ratio S 0  may be obtained through external field testing of multiple different environments. In some embodiments, the reference signal-to-noise ratio S 0  may be obtained through testing multiple different external field environments. For example, the external field environments may include: a city environment, a sea environment, a mountain environment, a plateau environment, etc. As such, the reference signal-to-noise ratio S 0  may accurately reflect a relationship between the remote control distance D between the UAV  100  and the remote control device  200  and the signal transmission power. 
     In some embodiments, the predetermined difference δS implemented in the control method, the UAV  100  and the remote control device  200  may be any suitable value obtained in the range of (2˜3) dB. For example, the value of the predetermined difference δS may include: 2 dB, 2.1 dB, 2.2 dB, 2.25 dB, 2.3 dB, 2.4 dB, 2.5 dB, 2.6 dB, 2.7 dB, 2.75 dB, 2.8 dB, 2.9 dB, or 3 dB. The value of the predetermined difference δS may be selected based on the flight velocity of the UAV  100 . As such, when the value of the predetermined difference δS is obtained from the range of (2˜3) dB, instability phenomenon of the signal transmission power caused by reducing the current signal transmission power of the UAV  100  and/or the remote control device  200  by a predetermined change value may be avoided. 
     In some embodiments, the predetermined change value Pstep implemented in the control method, the UAV  100  and the remote control device  200  may be any value obtained in the range of (0.5˜1) dB. For example, the predetermined change value Pstep may include: 0.5 dB, 0.55 dB, 0.6 dB, 0.65 dB, 0.7 dB, 0.75 dB, 0.8 dB, 0.85 dB, 0.9 dB, 0.95 dB, or 1 dB. The value of the predetermined change value Pstep may be selected based on the flight velocity of the UAV  100 . 
     Referring to  FIG. 14 , in some embodiments, the step of detecting a current signal-to-noise ratio St of a signal receiver of the UAV  100  and/or the remote control device  200  (including step S 11 ) to the step of obtaining an updated signal transmission power (step S 21  or S 33 ) or to the step of maintaining the current signal transmission power of the UAV  100  and/or the remote control device  200  unchanged (step S 34 ) may be executed once at every second predetermined time interval T 2 . 
     Referring to  FIG. 11 , the control method may be executed by the UAV  100 . In some embodiments, the step of detecting the current signal-to-noise ratio St of the first signal receiver  18  of the UAV  100  (including step S 11 ) executed by the first processor  10  of the UAV  100 , to the step of obtaining an updated signal transmission power (including step S 21  or S 33 ) executed by the first transmitter  12 , or to the step of maintaining the current signal transmission power of the UAV  100  and/or the remote control device  200  unchanged (step S 34 ) may be executed once at every second predetermined time interval T 2 . 
     In some embodiments, the control method may be executed by the remote control device  200 . In some embodiments, the step of detecting the current signal-to-noise ratio St of the second signal receiver  28  of the remote control device  200  (including step S 11 ) executed by the second processor  20  of the remote control device  200  to the step of obtaining an updated signal transmission power (including step S 21  or S 33 ) executed by the second transmitter  22 , or to the step of maintaining the current signal transmission power of the UAV  100  and/or the remote control device  200  unchanged (step S 34 ) may be executed once at every second predetermined time interval T 2 . 
     As such, at every second predetermined time interval T 2 , the UAV  100  and the remote control device  200  may obtain the most recent current signal-to-noise ratio, such that the UAV  100  and the remote control device  200  may obtain an updated signal transmission power based on the current signal-to-noise ratio St, the reference signal-to-noise ratio S 0 , the predetermined difference δS, and the predetermined change value Pstep, thereby realizing changing the signal transmission power of the remote control device  200  and the UAV  100  in real time. 
     In some embodiments, the second predetermined time interval T 2  implemented in the control method, the UAV  100 , and the remote control device  200  may be any suitable value selected from the range of (0.001-1) second. For example, the second predetermined time interval T 2  may include: 0.001 second, 0.005 second, 0.01 second, 0.05 second, 0.1 second, 0.15 second, 0.2 second, 0.25 second, 0.3 second, 0.35 second, 0.4 second, 0.45 second, 0.5 second, 0.55 second, 0.6 second, 0.65 second, 0.7 second, 0.75 second, 0.8 second, 0.85 second, 0.9 second, 0.95 second, or 1 second. The value of the second predetermined time interval T 2  may be selected based on the flight velocity of the UAV  100 . 
     A person having ordinary skill in the art can appreciate that when the description mentions “an embodiment,” “some embodiments,” “an illustrative embodiment,” “an example,” “a specific example,” or “some examples,” it means that specific characteristics, structures, materials, or features described with reference to the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, illustrative expression of the above terms does not necessarily mean the same embodiment or example. Further, the described specific characteristics, structures, materials, or features may be combined in a suitable manner in one or more embodiments or examples. 
     Processes or methods described in the flow charts or described in other manners may be understood as including one or more code modules, segments, or portions of executable instructions configured to execute specific logic functions or steps of a process. The scope of the preferred embodiments of the present disclosure may include other executions. Executions may not need follow the illustrated or described sequence or order. The functions may be executed in a substantially simultaneous manner or in a reversed order. These should be understood by a person having ordinary skills in the technical field of the embodiments of the present disclosure. 
     Logics and/or steps of illustrated in the flow chart or described in other manners may be regarded as a fixed-order sequence list of executable instructions configured to execute the logic functions. The logics and/or steps may be executed in any suitable non-transitory computer-readable medium, and may be used by instruction-execution systems, apparatuses, or devices (e.g., computer-based systems, systems having processors, or other systems that can retrieve instructions from the instruction-execution systems, apparatuses, or devices and execute the instructions), or may be used in combination with the instruction-execution systems, apparatuses, or devices. In the present specification, a “computer-readable medium” may include any device that can include, store, communicate, broadcast, or transfer programs to be used by instruction-execution systems, apparatuses, or devices. Examples of the computer-readable medium may include, but not be limited to, the following: an electrical connector (e.g., an electrical device) having one or multiple wirings, a portable computer disk (e.g., a magnetic device), a random access memory (“RAM”), a read only memory (“ROM”), an erasable programmable read only memory (“EPROM”) or a flash memory, an optical device, or a portable compact disc read only memory (“CDROM”). In some embodiments, the computer-readable medium may be paper on which the programs may be printed or other suitable medium, because the paper or other medium may be optically scanned. The scanned copy may be edited, interpreted, or if necessary processed using other suitable method to obtain the programs in an electrical manner. The programs can then be stored in a computer storage device. 
     A person having ordinary skills in the art can appreciate that various parts of the present disclosure may be implemented using related hardware, computer software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods may be executed by software or firmware stored in the computer-readable storage medium and executable by a suitable instruction-executing system. For example, if the present disclosure is executed by hardware, the hardware may include any of the following technologies known in the art or any combination thereof: a discrete logic circuit of a logic gate circuit configured to perform logic functions for digital signals, an application specific integrated circuit having suitable combinations of logic gate circuits, a programmable gate array (“PGA”), a field programmable gate array (“FPGA”), etc. 
     A person having ordinary skills in the art can understand that some or all of the steps of the above embodiments of the disclosed method may be implemented by a program instructing relevant hardware. The program may be stored in a computer-readable medium. When executed, the program may include one of the steps or a combination of the steps of the disclosed method. 
     Various functional units may be integrated in a single processing module, or may exist as separate physical units. In some embodiments, two or more units may be integrated in a single module. The integrated module may be executed by hardware or by software functional modules. If the integrated module is executed by software functional modules and sold or used as an independent product, the integrated module may also be stored in a computer-readable storage medium. 
     The storage medium mentioned above may be a read only storage device (e.g., memory), a magnetic disk, or an optical disk, etc. Although the above has shown and described the embodiments of the present disclosure, it should be understood that the above embodiments are illustrative, and cannot be understood as limiting the present disclosure. A person having ordinary skills in the art can modify, edit, replace, and vary the embodiments within the scope of the present disclosure.