Patent Publication Number: US-11662418-B2

Title: Blind area tracking method and apparatus for directional antenna and motion tracking system

Description:
This application is a continuation application of International Application No. PCT/CN2019/071993, filed on Jan. 16, 2019, which claims priority of Chinese Patent Application No. 201810031492.9, filed on Jan. 12, 2018, which is incorporated herein by reference in its entirely. 
    
    
     BACKGROUND 
     Technical Field 
     The present invention relates to the field of tracking system technologies, and in particular, to a blind area tracking method and apparatus for a directional antenna and a motion tracking system. 
     Related Art 
     As unmanned aerial vehicle technologies develop and mature, application scenarios of the unmanned aerial vehicle technologies become increasingly extensive. A large amount of measurement and control data needs to be exchanged between an unmanned aerial vehicle and a ground control system. Therefore, a motion tracking system may be adopted to ensure reliability of data transmission and improve a gain and an anti-interference capability during the data transmission. 
     A function of the motion tracking system is to isolate an effect of motion of a carrier (for example, a vehicle, a ship or an airplane) on an attitude of a directional antenna in a motion process of the carrier, and to ensure that the directional antenna is always aligned with a high-velocity maneuverable unmanned aerial vehicle, to implement continuous communication during the motion. For a frequently-used motion tracking system with an azimuth-pitch structure, there is a tracking blind area at a top location of the directional antenna. 
     When a tracking target flies through the tracking blind area, in the existing guidance manner, a one-time guidance policy is adopted, with which an azimuth of a tracking platform is directly driven to rotate to the other end of the blind area. In this guidance manner, the tracking target may be lost within the tracking blind area and a moving state of the tracking target needs to remain unchanged within the blind area. In this way, the motion tracking system can capture the tracking target again when the tracking target flies out of the blind area. 
     SUMMARY 
     To resolve the foregoing technical problem, embodiments of the present invention provide a blind area tracking method and apparatus and a motion tracking system that may keep effective tracking of a tracking target within a tracking blind area. 
     To resolve the foregoing technical problem, an embodiment of the present invention provides the following technical solution: a blind area tracking method for a directional antenna. The blind area tracking method includes: 
     acquiring a position and a velocity of a tracking target relative to the directional antenna; determining, according to the position and the velocity, whether the tracking target is located in a tracking blind area of the directional antenna; and driving, in a preset blind area guidance mode and when the tracking target is located in the tracking blind area, the directional antenna to rotate. 
     To resolve the foregoing technical problem, an embodiment of the present invention further provides the following technical solution: 
     a blind area tracking apparatus for a directional antenna. The blind area tracking apparatus includes: an information acquiring module, configured to acquire a position and a velocity of a tracking target; a blind area determining module, configured to determine, according to the position and the velocity, whether the tracking target is located in a tracking blind area of the directional antenna; and a driving module, configured to drive an azimuth axis and a pitch axis of the directional antenna to rotate, so that the directional antenna is aligned with the tracking target. 
     To resolve the foregoing technical problem, an embodiment of the present invention further provides the following technical solution: 
     a motion tracking system for an unmanned aerial vehicle. The motion tracking system includes a directional antenna, a motion platform, an information receiver and a control system; 
     the directional antenna being disposed on the motion platform and the motion platform being configured to track the unmanned aerial vehicle; the information receiver being configured to acquire a position of the directional antenna, a moving velocity of the motion platform and information about a position and a velocity of the unmanned aerial vehicle, the information being delivered by the unmanned aerial vehicle; and the control system being configured to drive, according to the position of the directional antenna, the moving velocity of the motion platform and the information about the position and the velocity of the unmanned aerial vehicle that are acquired by the information receiver and by using the foregoing blind area tracking method for a directional antenna, the directional antenna to rotate, so that the directional antenna keeps tracking of the unmanned aerial vehicle within the tracking blind area. 
     Compared with the prior art, the blind area tracking method provided in the embodiments of the present invention may help switch to a corresponding blind area guidance mode when an unmanned aerial vehicle enters a blind area, to implement all-the-way tracking of a tracking target and continuous communication between a directional antenna and the tracking target without temporarily losing the tracking target within the tracking blind area. In this way, a better tracking effect and a better communication effect are ensured. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more embodiments are described by way of example with reference to the corresponding figures in the accompanying drawings, and the descriptions are not to be construed as limiting the embodiments. Elements in the accompanying drawings that have same reference numerals are represented as similar elements, and unless otherwise particularly stated, the figures in the accompanying drawings are not drawn to scale. 
         FIG.  1    is a schematic diagram of an application environment according to an embodiment of the present invention. 
         FIG.  2    is a flowchart of a blind area tracking method according to an embodiment of the present invention. 
         FIG.  3    is a schematic diagram of a horizontal reference plane when a tracking target is close to a directional antenna according to an embodiment of the present invention. 
         FIG.  4    is a schematic diagram of a horizontal reference plane when a tracking target is away from a directional antenna according to an embodiment of the present invention. 
         FIG.  5    is a schematic diagram of a vertical reference plane according to an embodiment of the present invention. 
         FIG.  6    is a structural block diagram of a blind area tracking apparatus according to an embodiment of the present invention. 
         FIG.  7    is a structural block diagram of an electronic device according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     To facilitate the understanding of the present invention, the present invention is further described below in further detail with reference to the accompanying drawings and specific embodiments. It should be noted that, when an element is described to be “fixed on” another element, it may be directly fixed on the another element, or there may be one or more intermediate elements therebetween. When an element is described to be “connected to” another element, it may be directly connected to the another element, or there may be one or more intermediate elements therebetween. In this specification, orientation or position relationships indicated by the terms such as “up”, “down”, “inside”, “outside” and “bottom” are based on orientation or position relationships shown in the accompanying drawings, and are used only for ease of description of the present invention and for brevity, rather than indicating or implying that the mentioned apparatus or element needs to have a particular orientation or needs to be constructed and operated in a particular orientation. Therefore, such terms should not be construed as limiting of the present invention. In addition, terms “first”, “second” and “third” are only used to describe the objective and cannot be understood as indicating or implying relative importance. 
     Unless otherwise defined, meanings of all technical and scientific terms used in this specification are the same as those usually understood by persons skilled in the technical field to which the present invention belongs. Terms used in the specification of the present invention are merely intended to describe objectives of the specific embodiments, but are not intended to limit the present invention. A term “and/or” used in this specification includes any or all combinations of one or more related listed items. 
     In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other, provided that they do not constitute a conflict with each other. 
       FIG.  1    shows an application environment according to an embodiment of the present invention. As shown in  FIG.  1   , the application environment includes an unmanned aerial vehicle  10 , a directional antenna  20  and a control system  30 . 
     The unmanned aerial vehicle  10  may be any type of aerial unmanned aircraft, such as a four-axis unmanned aerial vehicle. Specifically, the unmanned aerial vehicle  10  may adopt a plurality of types of fuselage structures or shapes and may be driven by one or more motors to move at a specific velocity in a space. 
     As a carrier, the unmanned aerial vehicle  10  may carry different functional devices to be used in a plurality of possible application scenarios, such as terrain survey, high altitude shooting and surveillance. 
     The directional antenna  20  is a wireless transceiver configured to establish a communication channel with the unmanned aerial vehicle  10  and transmit data in real time. 
     To ensure an effect of communication between the directional antenna  20  and the unmanned aerial vehicle  10 , the directional antenna  20  needs to be aligned with the unmanned aerial vehicle  10  (that is, pointing toward the unmanned aerial vehicle  10 ) in the real-time data transmission to ensure a sufficient gain of the antenna. 
     To increase application scenarios of a motion tracking system, the directional antenna  20  may be carried by a corresponding carrier and moves following the unmanned aerial vehicle  10  through the motion of the carrier. Specifically, the corresponding carrier, for example, a vehicle, a ship or another aircraft, may be selected according to an actual application scenario. In addition to having sufficient mobility, the directional antenna  20  needs to maintain a proper target angle (that is, a direction to which the directional antenna points in a stereoscopic space) to keep tracking of the unmanned aerial vehicle  10 . 
     In this embodiment, as shown in  FIG.  1   , the target angle may be specifically represented by an azimuth a and a pitch b, which are on two planes perpendicular to each other. For ease of calculation and statement, it is specified that for the azimuth, the north represents 0°, a clockwise direction represents [0, π] and a counterclockwise direction represents [0, −π]; for the pitch, an angle above a horizontal reference plane is positive and an angle below the horizontal reference plane is negative. 
     The control system  30  is a control and computation center of the entire motion tracking system. The target angle of the directional antenna  20  may be correspondingly adjusted according to a relative position relationship and a moving state between the unmanned aerial vehicle  10  and the directional antenna  20  and using a corresponding algorithm or guidance method, so that the directional antenna  20  can always keep tracking of the unmanned aerial vehicle  10 , avoiding a communication disconnection. In this embodiment, the control system  30  may receive information about positions and velocities of the directional antenna and the unmanned aerial vehicle by using a GPS receiver and adjust and control the target angle of the directional antenna  20  accordingly. 
     The motion tracking system including the directional antenna  20  and the control system  30  has an azimuth-pitch structure, and there is a tracking blind area at a top of the directional antenna  20 . The blind area tracking method provided in the embodiments of the present invention may be applied to the control system  30  to keep continuous tracking of the unmanned aerial vehicle  10 , to avoid temporarily losing a target. 
       FIG.  2    is a flowchart of a blind area tracking method for a directional antenna according to an embodiment of the present invention. As shown in  FIG.  2   , the method includes the following steps: 
     Step  201 : Acquire a position and a velocity of a tracking target relative to a directional antenna. 
     Specifically, the tracking target may be a movable target with which the directional antenna needs to be aligned and establish a communication connection. In this embodiment, an unmanned aerial vehicle is used as an example of the tracking target. 
     To execute a corresponding task or implement a specific function, an unmanned aerial vehicle has corresponding position and velocity information at different moments. In this embodiment, a corresponding spatial coordinate system may be established with a position of the directional antenna as a reference point to represent information about a position and a velocity of the unmanned aerial vehicle relative to the directional antenna. Specifically, positions and velocities of the tracking target and the directional antenna are respectively acquired by using sensors with corresponding functions, and then the position and the velocity of the tracking target relative to the directional antenna are acquired. 
     Step  202 : Determine, according to the position and the velocity, whether the tracking target is located in a tracking blind area of the directional antenna. 
     According to a relative position relationship between the unmanned aerial vehicle  10  and the directional antenna  20  and velocity information of the unmanned aerial vehicle  10  and the directional antenna  20 , the control system  30  may determine through calculation whether the tracking target is within the tracking blind area. 
     Step  203 : Drive, in a preset blind area guidance mode and when the tracking target is located in the tracking blind area, the directional antenna to rotate. 
     The control system  30  supports two preset working modes, that is, the blind area guidance mode and a normal tracking mode. When the unmanned aerial vehicle  10  is within the tracking blind area, the control system  30  works in the blind area guidance mode to ensure that the directional antenna  20  can keep continuous tracking of the unmanned aerial vehicle  10 . A corresponding target angle control policy may be adopted to make the directional antenna  20  rotate accordingly to track the unmanned aerial vehicle, so that continuous communication between the directional antenna  20  and the unmanned aerial vehicle  10  may be implemented. 
     When the unmanned aerial vehicle  10  is out of the tracking blind area, the control system  30  may adopt the normal tracking mode. The control system  30  solves relative position information of the unmanned aerial vehicle  10  and the directional antenna  20  to acquire the target angle of the directional antenna  20  (that is, the foregoing azimuth and pitch), thereby driving the directional antenna to rotate (step  204 ). Specifically, the control system  30  may adjust the target angle of the directional antenna by driving an azimuth axis and a pitch axis of the directional antenna to rotate, so that the directional antenna is aligned with the unmanned aerial vehicle (that is, the tracking target). 
     In some embodiments, whether the unmanned aerial vehicle is within the tracking blind area may be specifically determined based on two different phases, that is, a phase in which the unmanned aerial vehicle enters the tracking blind area and a phase in which the unmanned aerial vehicle leaves the tracking blind area. 
     That the tracking target is close to the directional antenna belongs to the phase of determining whether the unmanned aerial vehicle enters the tracking blind area. In this case, a critical time at which the tracking target enters the tracking blind area may be first calculated. The critical time is a moment when the unmanned aerial vehicle  10  just enters a boundary of the tracking blind area, and may be used as a specific indicator for determining whether the unmanned aerial vehicle  10  enters the tracking blind area. 
     Then, whether the tracking target enters the tracking blind area is determined according to the critical time and the position and the velocity of the tracking target. After the critical time is acquired through calculation, whether the unmanned aerial vehicle  10  has entered the tracking blind area may be determined according to a current moving state of the unmanned aerial vehicle  10 . 
       FIG.  3    is a schematic diagram of projections of the unmanned aerial vehicle  10  and the directional antenna  20  in a horizontal reference plane according to an embodiment of the present invention. With reference to the projections shown in  FIG.  3   , the following describes, by using a geometrical relationship, a specific process of determining. 
     As shown in  FIG.  3   , AC represents a projection of the directional antenna currently pointing to the horizontal reference plane. A represents the position of the directional antenna. P′ represents a projection of the tracking target in the horizontal reference plane and v′ represents a velocity projection of the tracking target in the horizontal reference plane. 
     Along a velocity direction, there is a straight line L 1  in the horizontal reference plane. B represents an intersection point of the straight line L 1  that passes through v′ in the horizontal reference plane and a vertical line L 2  perpendicular to the straight line L 1 . The vertical line L 2  is a vertical line that passes through the point A. 
     The critical time may be calculated using the following formula (1): 
     
       
         
           
             
               
                 
                   
                     
                       K 
                       ⁢ 
                       
                         
                           φ 
                           . 
                         
                         max 
                       
                       ⁢ 
                       
                         t 
                         I 
                       
                     
                     = 
                     
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                       ⁢ 
                          
                       
                         ( 
                         
                           
                             
                               v 
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                             ⁢ 
                             
                               t 
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                             A 
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                             B 
                           
                         
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                   ; 
                 
               
               
                 
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     K representing an azimuth velocity margin coefficient, {dot over (φ)} max  representing a maximum azimuth velocity of the directional antenna and t 1  representing the critical time. 
     The critical time is a time value that meets formula (1). When other data is known, the control system  30  may acquire, through derivation and calculation, the critical time that meets formula (1). 
     The azimuth velocity margin coefficient is a percentage accounting for the maximum azimuth velocity of the directional antenna. To ensure that the directional antenna has a sufficient margin to meet requirements of some acceleration maneuvering motions or steering motions of the unmanned aerial vehicle  10  within the tracking blind area, a proper value may be set for K according to actual conditions. 
     In some embodiments, the value of K may be set to 80%. That is, the directional antenna has a 20% angular velocity margin within the tracking blind area. In this way, it may be ensured that the directional antenna  20  has an additional steering capability in the preset blind area guidance mode, so that an effect of tracking the unmanned aerial vehicle  10  can be maintained under extreme conditions such as acceleration maneuvering or carrier steering of the unmanned aerial vehicle  10  within the tracking blind area. 
     Correspondingly, when P′B&lt;v′t 1 , it is determined that the tracking target enters the tracking blind area. When P′B&gt;v′t 1 , it is determined that the tracking target is out of the tracking blind area. 
     In some embodiments, when the unmanned aerial vehicle is in a phase of being close to the directional antenna and entering the tracking blind area, with reference to the schematic diagram shown in  FIG.  3   , an azimuth velocity of the directional antenna may be calculated using the following formula (2): 
                           φ   .     I     =       φ   2       t   1         ;       t   1     =         P   ′     ⁢   B       v   ′           ,           (   2   )               
{dot over (φ)} 1  representing the azimuth velocity and φ 2  representing an included angle (that is, an angle CAB) between the projection of the directional antenna currently pointing to the horizontal reference plane and the vertical line.
 
     After acquiring the azimuth velocity through calculation, the control system  30  may drive the directional antenna  20  to rotate at the azimuth velocity (that is, to rotate around a direction axis at a particular angular velocity), thereby keeping the tracking of the unmanned aerial vehicle  10 . 
     That the tracking target is away from the directional antenna belongs to the phase of determining whether the unmanned aerial vehicle leaves the tracking blind area.  FIG.  4    is a schematic diagram of the horizontal reference plane when the unmanned aerial vehicle is away from the directional antenna according to an embodiment of the present invention. 
     As shown in  FIG.  4   , AC represents a projection of the directional antenna currently pointing to the horizontal reference plane. A represents the position of the directional antenna. P′ represents a projection of the tracking target in the horizontal reference plane and v′ represents a velocity projection of the tracking target in the horizontal reference plane. 
     Along a velocity direction, there is a straight line L 1  in the horizontal reference plane. B represents an intersection point of the straight line L 1  that passes through v′ in the horizontal reference plane and a vertical line L 2  perpendicular to the straight line L 1 . The vertical line L 2  is a vertical line that passes through the point A. D represents an intersection point between the tracking blind area and the straight line L 1 . D meets the following formula: P′D=v′t 2 ;
 
∠BAP′=φ 3 ,∠BAC=φ 4  and ∠CAD=φ 5 .
 
     Whether the tracking target leaves the tracking blind area is detected using a predetermined detection period, which specifically includes: 
     determining, using the following formula (3), whether the unmanned aerial vehicle  10  has flown away from the tracking blind area: 
     
       
         
           
             
               
                 
                   
                     
                       
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     t 0     +    representing the detection period, P′ representing the projection of the tracking target in the horizontal reference plane, K representing the azimuth velocity margin coefficient, {dot over (φ)} max  representing the maximum azimuth velocity of the directional antenna and v′ representing the velocity projection of the tracking target in the horizontal reference plane. 
     In some embodiments, the detection period may be a very short period of time, for example, 1 ms or a longer/shorter period. The detection period may be specifically set by persons skilled in the art according to actual conditions. 
     Formula (3) is a conditional expression for determining. When the acquired information about the velocity and the position of the unmanned aerial vehicle can meet formula (3), it may be determined that the tracking target has not left the tracking blind area. When the acquired information about the velocity and the position cannot meet formula (3), it is determined that the tracking target has left the tracking blind area. 
     Based on the schematic diagram shown in  FIG.  4   , in some embodiments, when the tracking target is in a phase of being away from the directional antenna but not leaving the tracking blind area, an azimuth velocity of the directional antenna may be calculated using the following formula (4): 
     
       
         
           
             
               
                 
                   
                     
                       
                         φ 
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                         t 
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                   4 
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     t 2  being calculated using the following formula (5): 
     
       
         
           
             
               
                 
                   
                     
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     Similarly, after acquiring the corresponding azimuth velocity through calculation, the control system  30  may drive the directional antenna to rotate at the corresponding azimuth velocity (that is, to drive the directional antenna to rotate around a direction axis), thereby implementing continuous tracking of the unmanned aerial vehicle within the tracking blind area. 
     In addition to the application environment of a motion tracking platform for the unmanned aerial vehicle shown in  FIG.  1   , the method provided in the embodiments of the present invention may also be applied to another motor-driven power device, to control the directional antenna to keep tracking of the tracking target within the tracking blind area. 
     In some other embodiments, in addition to control of the azimuth velocity, the pitch of the directional antenna may be further adjusted, thereby ensuring that the directional antenna can track the unmanned aerial vehicle well within the tracking blind area and maintaining good communication with the unmanned aerial vehicle. 
       FIG.  5    is a schematic diagram of adjusting the pitch of the directional antenna according to an embodiment of the present invention. As shown in  FIG.  5   , AC represents a projection of the directional antenna currently pointing to the horizontal reference plane and P″ represents a projection of the tracking target in a vertical reference plane, the vertical reference plane P 1  being a vertical plane in which the azimuth of the directional antenna is located. 
     The control system  30  may calculate the pitch of the directional antenna using the following formula (6):
 
θ=∠CAP″  (6);
 
     θ representing the pitch. 
     After determining the pitch of the directional antenna, the control system  30  further drives the directional antenna to rotate at the pitch (that is, the control system  30  drives the directional antenna to rotate around the pitch axis), to track the unmanned aerial vehicle. 
     There are two different phases in the blind area tracking method provided in the embodiments of the present invention. In the first phase, the unmanned aerial vehicle is close to the directional antenna. In the second phase, the unmanned aerial vehicle is away from the directional antenna. 
     In the first phase, the critical time used for determining whether the unmanned aerial vehicle has entered the tracking blind area is calculated using formula (1). After the unmanned aerial vehicle enters the tracking blind area, the azimuth velocity of the directional antenna is calculated using formula (2). 
     In the second phase, formula (3) is used as a condition for determining, after sampling is performed at intervals of a particular period of time, whether the unmanned aerial vehicle has left the tracking blind area. If the unmanned aerial vehicle has not left the tracking blind area, the azimuth velocity of the directional antenna is calculated using formulas (4) and (5). 
     In addition, if the unmanned aerial vehicle is within the tracking blind area, a current pitch of the directional antenna is calculated using formula (6). 
     According to the blind area tracking method provided in the embodiments of the present invention, whether the tracking target enters or leaves the blind area may be determined in real time, and real-time guidance for the azimuth and the pitch of the directional antenna is implemented within the blind area, thereby ensuring accuracy of tracking within the tracking blind area. 
     In the foregoing preset blind area guidance mode, the target may be continuously tracked within the blind area. The azimuth velocity margin coefficient is set, and a particular azimuth velocity adjustment margin is reserved. Therefore, the directional antenna may track the target well even when the tracking target is maneuvering in the tracking blind area. 
     An embodiment of the present invention further provides a blind area tracking apparatus.  FIG.  6    is a schematic structural diagram of the blind area tracking apparatus according to this embodiment of the present invention. As shown in  FIG.  6   , the blind area tracking apparatus includes an information acquiring module  610 , a blind area determining module  620  and a driving module  630 . 
     The information acquiring module  610  is configured to acquire a position and a velocity of a tracking target. The blind area determining module  620  is configured to determine, according to the position and the velocity, whether the tracking target is located in a tracking blind area of a directional antenna. The driving module  630  is configured to drive the directional antenna to rotate around an azimuth axis and a pitch axis, so that the directional antenna is aligned with the tracking target. 
     As shown in  FIG.  1   , in this embodiment, a direction to which the directional antenna points in a stereoscopic space may be represented by an azimuth and a pitch, which are on two planes perpendicular to each other. The azimuth axis is an axis corresponding to the azimuth and may be an axis Z in  FIG.  1   . The pitch axis is an axis corresponding to the pitch and may be an axis Y in  FIG.  1   . 
     When the directional antenna rotates around the azimuth axis, the azimuth changes accordingly. Similarly, when the pitch axis of the directional antenna rotates, the pitch axis also changes accordingly. 
     Therefore, after determining an azimuth velocity and a pitch that are required, the driving module  630  may control a current direction of the directional antenna by separately controlling a velocity at which the directional antenna rotates around the azimuth axis and an angle at which the directional antenna rotates around the pitch axis, to ensure that the directional antenna points toward the tracking target. 
     During actual operations, the information acquiring module  610  acquires the position and the velocity of the tracking target relative to the directional antenna first. Then, the blind area determining module  620  determines, according to the position and the velocity, whether the tracking target is located in the tracking blind area of the directional antenna. 
     According to a result of the determining by the blind area determining module  620 , the driving module  630  drives, in a preset blind area guidance mode and when the tracking target is located in the tracking blind area, the directional antenna to rotate around the azimuth axis and the pitch axis. When the tracking target is out of the tracking blind area, the driving module  630  drives, in a normal tracking mode, the directional antenna to rotate around the azimuth axis and the pitch axis. 
     In some embodiments, as shown in  FIG.  6   , the blind area determining module  620  may specifically include a blind area entry calculation unit  621  and a blind area exit calculation unit  622 . 
     The blind area entry calculation unit  621  is configured to: calculate a critical time at which the tracking target enters the tracking blind area when the tracking target is close to the directional antenna; and determine whether the tracking target enters the tracking blind area according to the critical time and the position and the velocity of the tracking target. 
     The blind area exit calculation unit  622  is configured to detect, by using a predetermined detection period when the tracking target is away from the directional antenna, whether the tracking target leaves the tracking blind area. That is, determining whether the tracking target is within the tracking blind is divided into two different phases. 
     Specifically, according to calculation results of the blind area entry calculation unit  621  and the blind area exit calculation unit  622 , the driving module  630  may specifically adopt the corresponding blind area guidance mode or normal tracking mode to control the azimuth axis and the pitch axis of the directional antenna to rotate, to keep tracking of an unmanned aerial vehicle. 
     The blind area entry calculation unit  621 , the blind area exit calculation unit  622  and the driving module  630  may specifically perform the steps of the calculating method (that is, the preset blind area guidance mode) provided in the foregoing method embodiments to acquire the azimuth and the pitch of the directional antenna through calculation. 
     It should be noted that, the foregoing method and apparatus embodiments are implemented based on a same inventive concept. Technical effects and technical features that may be provided in the method embodiments may be executed or implemented by corresponding functional modules in the apparatus embodiments. For ease of description, details are not described herein again. 
       FIG.  7    is a schematic structural diagram of an electronic device according to an embodiment of the present invention. The electronic device may be used as a basis for hardware of the control system  30  to perform the blind area tracking method provided in the foregoing method embodiments. As shown in  FIG.  7   , the electronic device  70  includes one or more processors  701  and a memory  702 . One processor  701  is used as an example in  FIG.  7   . 
     The foregoing electronic device may further include an input apparatus  703  and an output apparatus  704 . Certainly, another suitable apparatus module may be added or reduced according to actual conditions. 
     The processor  701 , the memory  702 , the input apparatus  703  and the output apparatus  704  may be connected using a bus or in another manner. In  FIG.  7   , connection using a bus is used as an example. 
     As a non-volatile computer-readable storage medium, the memory  702  may be configured to store a non-volatile software program, a non-volatile computer executable program and module, such as a program instruction or module corresponding to the blind area tracking method provided in the embodiments of the present invention, for example, the information acquiring module  610 , the blind area determining module  620  and the driving module  630  shown in  FIG.  6   . The processor  701  executes various functional applications and data processing of a server by running the non-volatile software program, instruction and module stored in the memory  702 . That is, the processor  701  implements the blind area tracking method provided in the foregoing method embodiments. 
     The memory  702  may include a program storage area and a data storage area. The program storage area may store an operating system, and an application program required by at least one function. The data storage area may store data created according to use of the blind area tracking apparatus, and the like. In addition, the memory  702  may include a high speed random access memory, and may also include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory, or another non-volatile solid-state storage device. In some embodiments, the memory  702  may optionally include a memory disposed remotely relative to the processor  70 . Examples of the foregoing network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communications network and a combination thereof. 
     The input apparatus  703  may receive inputted numerical or character information and generate a key signal input related to user settings and function control of the blind area tracking apparatus. The output apparatus  704  may include a display device such as a display screen. The one or more modules are stored in the memory  702  and perform, when executed by the one or more processors  701 , the blind area tracking method provided in any of the foregoing method embodiments. 
     Persons of skilled in the art may further be aware that, each step of the exemplary motor control method described in the embodiments disclosed in this specification can be implemented by using electronic hardware, computer software, or a combination thereof. To clearly describe interchangeability between the hardware and the software, compositions and steps of each example have been generally described according to functions in the foregoing descriptions. Whether the functions are performed by hardware or software depends on particular applications and design constraint conditions of the technical solutions. 
     Persons skilled in the art may use different methods to implement the described functions for each particular application, but it should not be considered that the implementation goes beyond the scope of the present invention. The computer software may be stored in a computer-readable storage medium. When the program is executed, the program may include the procedures of the embodiments of the foregoing methods. The storage medium may be a magnetic disk, an optical disc, a read-only memory, a random access memory, or the like. 
     Finally, it should be noted that the foregoing embodiments are merely intended for describing the technical solutions of the present invention, but not for limiting the present invention. Under the thinking of the present invention, combinations may also be made between the technical features in the foregoing embodiments or in different embodiments, the steps may be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for simplicity. Although the present invention is described in detail with reference to the foregoing embodiments, persons of ordinary skill in the art should understand that they may still make modifications to the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features thereof, without departing from the scope of the technical solutions of the embodiments of the present invention.