Patent Publication Number: US-2018054572-A1

Title: Control device, imaging device, mobile object, control method and program

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation application of PCT Application No. PCT/JP2016/067553, filed on Jun. 13, 2016, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     The disclosed embodiments relate to control devices, imaging devices, mobile objects, control methods, and programs. 
     BACKGROUND 
     A television camera device is disclosed in patent literature 1. A handle-attached seat can be attached on the upper portion of the camera unit of the television camera device. A handle lower end portion that can slide in a groove of the handle-attached seat can be formed on the handle. As a result, deterioration in handle balance can be suppressed even while moving the center of gravity of the camera. 
     Patent Literature 1 Japanese Patent Application Publication No. 2007-335990 
     SUMMARY 
     There are sometimes demands to appropriately control the attitude of an optical device based on at least one of the weight or the center of gravity of the optical device. 
     In one aspect, a control device can include an acquisition unit and a control unit. The acquisition unit can acquire information that indicates at least one of the mass or the center of gravity position of an optical device having one or more lens. The control unit can control the attitude of the optical device based on at least one of the mass or the center of gravity position indicated in information acquired by the acquisition unit. 
     The acquisition unit can acquire information that indicates the mass and the center of gravity position of the optical device. The control device can control the attitude of the optical device based on the mass and the center of gravity position of the optical device indicated in information acquired by the acquisition unit. 
     Information that indicates a plurality of center of gravity positions of the optical device can be acquired, corresponding to a plurality of respective positions of movable lenses from among one or more lens. 
     The plurality of center of gravity positions of the optical device can correspond to a plurality of respective focal distances of the optical device. 
     The plurality of center of gravity positions of the optical device can correspond to a plurality of respective focus positions of the optical device. 
     A measurement unit for measuring the center of gravity position of the optical device can be further provided. The acquisition unit can acquire information that indicates a first center of gravity position and a second center of gravity position. The first center of gravity position is the center of gravity position of the optical device measured by the measurement unit when the movable lens is in a first position. The second center of gravity position is the center of gravity position of the optical device measured by the measurement unit when the movable lens is in a second position. 
     The optical device can be held with the ability to rotate centrally around a rotational axis. The measurement unit can measure a first center of gravity position and a second center of gravity position when the rotation angle around the rotational axis of the optical device is a first angle. It can measure the first center of gravity position and the second center of gravity position when the rotation angle around the rotational axis of the optical device is at a second angle. 
     The optical device can be detachable from the control device. The optical device can be rotatably held with the rotational axis of a direction different from the gravitational direction as the center. The measurement unit can measure an external force applied on the optical device in a first state in which the optical device is not mounted on the control device and a second state in which the optical device is mounted on the control device. It can also measure the center of gravity position of the optical device based on the external force in the first state and the external force in the second state. 
     The optical device can be detachable from the control device. The control device can further include a storage unit for storing center of gravity position information that indicates the center of gravity position of the optical device measured by the measurement unit and associating it with identification information of the optical device. The acquisition unit can calculate the center of gravity position of the optical device based on the center of gravity position indicated by the center of gravity position information stored in the storage unit and associates it with identification information of the optical device mounted to the control device. 
     The optical device can be detachable from the control device. The optical device can have a storage unit for storing information that indicates at least one of the mass or the center of gravity position of the optical device. The acquisition unit can acquire information that indicates at least one of the mass or the center of gravity position of the optical device from the optical device mounted on the control device. 
     The storage unit can store information that indicates an actual measured value of the center of gravity position of the optical device. The acquisition unit can acquire information that indicates an actual measured value of the mass and the center of gravity position of the optical device from the optical device mounted on the control device. 
     The storage unit can store information that indicates the mass and the center of gravity position of the optical device. The acquisition unit can acquire information that indicates the mass and the center of gravity position of the optical device from the optical device mounted on the control device. 
     The acquisition unit can acquire information that indicates the center of gravity position of the optical device from the optical device by communicating with the optical device when the optical device is mounted on the control device. 
     The optical device can be detachable from the control device. The control device can further include a storage unit for associating classifications of a plurality of optical devices with identifying classification information and storing information that indicates at least one of the mass or the center of gravity position of the optical devices of each respective classification. The acquisition unit can acquire information that indicates at least one of the mass or the center of gravity position stored in the storage unit and associates it with classification information of the optical device mounted on the control device. 
     The control unit can control the attitude of the optical device based on a desired value of the attitude of the optical device, a detected value of the attitude of the optical device, and the attitude of the optical device estimated based on the information acquired by the acquisition unit. 
     The optical device can further have an imaging unit for capturing an image formed by one or more lens. 
     In one aspect, an imaging device can include the control device described above and an imaging unit for capturing an image formed by one or more lens. 
     The one or plurality of lenses can be included in an interchangeable lens that is detachable from the imaging unit. 
     In one aspect, in a mobile object provided with the control device, an acquisition unit can acquire information that indicates at least one of the mass or the center of gravity position of the optical device during a period from a time when power is applied to the mobile object until a time when the mobile object begins moving. 
     A drive unit, a detection unit and a verification unit can be further provided. The drive unit can move the mobile object. The detection unit can detect the state of the mobile object or the state around the mobile object. The verification unit can verify an operation verification of the drive unit and detection unit can be further provided. The acquisition unit can acquire information that indicates at least one of the mass or the center of gravity position of the optical device while the verification unit is executing the operation verification. 
     A step for acquiring information that indicates at least one of the mass or the center of gravity position of the optical device having one or more lens, and a step for controlling the attitude of the optical device based on at least one of the mass or the center of gravity position indicated by the acquired information may be provided. 
     In one aspect, a program executes the control method in a computer. 
     The features described above can also be arranged into a variety of sub-combinations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a configuration of a system. 
         FIG. 2  illustrates a function block of a UAV  100 . 
         FIG. 3  illustrates when an optical device  190  is held in a reference attitude. 
         FIG. 4  illustrates a distance hy until a center of gravity position G from a yaw axis. 
         FIG. 5  illustrates a format of first center of gravity position information stored in a memory  106  of the UAV body  101 . 
         FIG. 6  illustrates a format of second center of gravity position information stored in the memory  106  of the UAV body  101 . 
         FIG. 7  illustrates a format of third center of gravity position information illustrating a center of gravity position of a lens device  160 . 
         FIG. 8  illustrates when the lens device  160  is not mounted to an imaging unit  140 . 
         FIG. 9  illustrates a process for calculating hp from the center of gravity position of the lens device  160 . 
         FIG. 10  is a flowchart illustrating center of gravity position measurement procedures, in which hp and hy are measured. 
         FIG. 11  illustrates a format of fourth center of gravity position information stored in the UAV body  101  in another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present disclosure is described below using embodiments of the disclosure, but the embodiments below do not limit the disclosure according to the scope of the claims. All combinations of features described in the embodiments are not necessary for the means to solve the disclosure. 
     The scope of the claims, specification, drawings, and abstract include matters subject to protection by copyright. The owner of copyright does not raise objections to duplication by any person of these documents if it is as displayed in files or records of the Patent Office. However, all copyright is retained in other cases. 
       FIG. 1  is an exemplary diagram of a configuration of a system. The system can include an unmanned aerial vehicle (UAV)  100 . The UAV  100  can include a UAV body  101 , a plurality of rotary wings  108 , a gimbal  110 , and an optical device  190 . The optical device  190  can include an imaging unit  140  and a lens device  160 . The UAV  100  is an example of a mobile object provided with a subject. A mobile object can be a concept including other aerial vehicles that move through the air, vehicles that move on the ground, ships that move on the water, etc. in addition to UAV. The optical device  190  can function as an imaging device. 
     The UAV  100  can fly by controlling the rotation of the plurality of rotary wings  108 . The UAV  100  can fly using, for example, four rotary wings. The number of rotary wings  108  is not limited to four. The UAV  100  can be a fixed-wing aircraft that does not have rotary wings  108 . 
     The gimbal  110  can support the imaging unit  140  and lens device  160  so that the attitude of the imaging unit  140  and lens device  160  to the gimbal  110  can be changed. The gimbal  110  can rotatably support the imaging unit  140  and the lens device  160  with at least one axis as the center. For example, the gimbal  110  rotatably supports the imaging unit  140  and the lens device  160  with a respective pitch axis, roll axis, and yaw axis as the center. The gimbal  110  can hold the imaging unit  140 , and can hold the lens device  160 . 
     The imaging unit  140  can generate and record image data of an optical image formed via the lens device  160 . The lens device  160  can be a so-called interchangeable lens. The lens device  160  can be detachable from the imaging unit  140 . 
       FIG. 2  illustrates a function block of the UAV  100 . The UAV  100  can include the UAV body  101 , the gimbal  110 , and the optical device  190 . The UAV body  101  can include a communication interface  102 , a UAV control unit  104 , a memory  106 , a drive unit  107 , and a detection unit  105 . 
     The drive unit  107  can be a mechanism for moving the UAV  100 . The drive unit  107  can include, for example, a plurality of rotary wings and a plurality of drive motors that drive the plurality of rotary wings. The UAV  100  can fly due to the drive unit  107  driving. 
     The communication interface  102  can communicate with an external transmitter. The communication interface  102  can receive various commands from a remote transmitter. The UAV control unit  104  can control the flight of the UAV  100  following the commands received from the transmitter. The UAV control unit  104  can control the gimbal  110 , the imaging unit  140 , and the lens device  160 . The UAV control unit  104  can be configured by microprocessors such as CPU or MPU, microcontrollers such as MCU, etc. The memory  106  can store programs etc. necessary for the UAV control unit  104  to control the gimbal  110 , the imaging unit  140 , and the lens device  160 . The memory  106  can be a computer readable recording medium, and can include at least one flash memory such as SRAM, DRAM, EPROM, EEPROM, USB memory etc. The memory  106  can be provided on a housing of the UAV  100 , and can be removably provided with the housing of the UAV  100 . The UAV control unit  104  and a gimbal control unit  112  can function as a control device of the UAV  100 . In such case, a program for adjusting the center of gravity position of an object system including the optical device  190  is read from the memory  106  and executed. The UAV control unit  104  can function as a control device of the UAV  100 . 
     The detection unit  105  can detect the state of the UAV  100  and the state around the UAV  100 . The detection unit  105  can detect, for example, a position including the latitude, longitude, and height of the UAV  100 , and a heading corresponding to the orientation of the nose of the UAV  100 . The detection unit  105  can include an imaging device for sensing that images the surroundings of the UAV  100 . 
     The UAV control unit  104  can include a verification unit  188 . The verification unit  188  can execute the initialization of the UAV  100  before flying. The verification unit  188  can execute an operation verification of the drive unit  107  and the detection unit  105 . The verification unit  188  can execute the operation verification of the drive unit  107  and the detection unit  105  before the UAV  100  begins to fly. The verification unit  188  can execute an operation verification of various sensors that detect the state of a drive motor that drives the rotary wings and the state of the UAV  100 . The period of time in which initialization is executed is an example of the period of time from when power is applied to the UAV  100  until the UAV  100  begins moving. 
     The gimbal  110  can have the gimbal control unit  112 , a yaw axis driver  114 , a pitch axis driver  116 , a roll axis driver  118 , a yaw axis drive motor  124 , a pitch axis drive motor  126 , a roll axis drive motor  128 , and a carrier  130 . 
     The carrier  130  can rotatably support the imaging unit  140  and the lens device  160  with the yaw axis, pitch axis, and roll axis as the center. The carrier  130  can include a yaw axis rotation mechanism  134 , a pitch axis rotation mechanism  136  and a roll axis rotation mechanism  138 . The yaw axis rotation mechanism  134  can rotate the imaging unit  140  and the lens device  160  using the yaw axis drive motor  124  with the yaw axis as the center. The pitch axis rotation mechanism  136  can rotate the imaging unit  140  and the lens device  160  using the pitch axis drive motor  126  with the pitch axis as the center. The roll axis rotation mechanism  138  can rotate the imaging unit  140  and the lens device  160  using the roll axis drive motor  128  with the roll axis as the center. 
     The gimbal control unit  112  is an example of a control unit that controls the attitude of the optical device  190 . The gimbal control unit  112  can acquire an operation command for the gimbal  110  from the UAV control unit  104 . This operation command can include a desired value of the yaw angle, a desired value of the pitch angle, and a desired value of the roll angle. The yaw angle can be the rotational angle of the optical device  190  around the yaw axis. The pitch angle can be the rotational angle of the optical device  190  around the pitch axis. The roll angle can be the rotational angle of the optical device  190  around the roll axis. 
     The gimbal control unit  112  can output an operation signal to the respective yaw axis driver  114 , pitch axis driver  116 , and roll axis driver  118  based on the operation command from the UAV control unit  104 . The yaw axis driver  114 , pitch axis driver  116 , and the roll axis driver  118  can drive the yaw axis drive motor  124 , pitch axis drive motor  126 , and roll axis drive motor  128  following the operation signal. The yaw axis rotation mechanism  134 , pitch axis rotation mechanism  136 , and roll axis rotation mechanism  138  can rotate, driven by the yaw axis drive motor  124 , pitch axis drive motor  126 , and roll axis drive motor  128 . The attitude of the optical device  190  can be adjusted as a result. 
     The imaging unit  140  can have an imaging control unit  142 , an imaging element  144 , and a memory  146 . The imaging control unit  142  can be configured by a microprocessor such as CPU and MPU, a microcontroller such as MCU, etc. The imaging control unit  142  can control the imaging unit  140  and the lens device  160  based on an operation command of the imaging unit  140  and the lens device  160  from the UAV control unit  104 . The memory  146  can be a computer readable recording medium, and can include at least one flash memory such as SRAM, DRAM, EPROM, EEPROM, USB memory etc. The memory  146  can be provided inside a housing of the imaging unit  140 . It can also be removably provided with the housing of the imaging unit  140 . 
     The imaging element  144  can be held in the housing of the imaging unit  140 , can generate image data of an optical image formed via the lens device  160 , and can output this image data to the imaging control unit  142 . The imaging control unit  142  can store the image data output from the imaging element  144  to the memory  146 . The imaging control unit  142  can output and store image data to the memory  106  via the UAV control unit  104 . 
     The lens device  160  can have a lens control unit  162 , a lens  164 , a lens  166  and a lens  168 . The lens  164 , the lens  166  and the lens  168  can be arranged inside a body tube of the lens device  160 . One or all of the lens  164 , the lens  166 , and the lens  168  can be arranged to be able to move along the optic axis. A lens that can move along the optic axis is one example of a movable lens. The lens control unit  162  moves at least one of the lens  164 , lens  166 , or lens  168  along the optical axis following the lens operation command from the imaging control unit  142 . The lens device  160  can have one lens, or can have a plurality of lenses. The image formed by the lens of the lens device  160  is captured by the imaging unit  140 . 
     An example is described in the present embodiment wherein the UAV  100  can include the UAV control unit  104 , the gimbal control unit  112 , the imaging control unit  142  and the lens control unit  162 . However, one of the control units can execute a process executed in two or three of the UAV control unit  104 , the gimbal control unit  112 , the imaging control unit  142  and the lens control unit  162 . Processes executed in the UAV control unit  104 , the gimbal control unit  112 , the imaging control unit  142  and the lens control unit  162  can be executed in one control unit. 
     The acquisition unit  170  can acquire information that indicates at least one of the mass or the center of gravity position of the optical device  190 . The gimbal control unit  112  can control the attitude of the optical device  190  based on at least one of the mass or the center of gravity position indicated in the information acquired by the acquisition unit  170 . The time period for acquiring information that indicates at least one of the mass or the center of gravity position of the optical device  190  can be within a time period in which the initialization of the UAV  100  can be executed. The acquisition unit  170  can acquire information that indicates at least one of the mass or the center of gravity position of the optical device  190  while the verification unit  188  is executing the operation verification. 
     The acquisition unit  170  can acquire information that indicates the mass and the center of gravity position of the optical device  190 . The gimbal control unit  112  can control the attitude of the optical device  190  based on the mass and the center of gravity position of the optical device  190  indicated in the information obtained by the acquisition unit  170 . 
     The acquisition unit  170  can acquire information that indicates the plurality of center of gravity positions of the optical device  190  corresponding to a plurality of respective positions of a movable lens from among the one or more lens. The plurality of center of gravity positions of the optical device  190  can correspond to respective plurality of focal lengths of the optical device  190 . The plurality of center of gravity positions of the optical device  190  can correspond to respective plurality of focus positions of the optical device  190 . 
     The measuring unit  180  measures the center of gravity position of the optical device  190 . The acquisition unit  170  acquires information that indicates a first center of gravity position and a second center of gravity position. The first center of gravity position is the center of gravity position of the optical device  190  measured by the measurement unit  180  when the movable lens is in a first position. The second center of gravity position which is the center of gravity position of the optical device  190  measured by the measurement unit  180  when the movable lens is in a second position. 
     When the movable lens is in the first position, the lens device  160  can be at the telephoto end. That is to say, the focal length of the lens device  160  can be at its greatest length. The lens device  160  can be at the wide angle end when the movable lens is at the second position. That is to say, the focal length of the lens device  160  can be at its shortest length. The measurement unit  180  can measure the center of gravity position of the optical device  190  when the lens device  160  is in each of a plurality of positions between the telephoto end and the wide angle end. 
     When the movable lens is in the first position, the focus position of the lens device  160  can be at an infinite end. The focus position of the lens device  160  can be at the closest end when the movable lens is in the second position. The measurement unit  180  can measure the center of gravity position of the optical device  190  when the focus position of the lens device  160  is in each of a plurality of focus positions between the infinite end and the closest end. 
     The optical device  190  can be held with the ability to rotate centrally around a rotational axis. For example, the optical device  190  can be held with the ability to rotate around the respective axes of the yaw axis, pitch axis, and roll axis. The measurement unit  180  can measure a first center of gravity position and second center of gravity position when the rotational angle around the rotational axis of the optical device  190  is at a first angle, and also can measure the first center of gravity position and the second center of gravity position when the rotational angle around the rotational axis of the optical device  190  is at a second angle. For example, the measurement unit  180  can measure the first center of gravity position and second center of gravity position when the rotational angle around the pitch axis of the optical device  190  is at the first angle, and also can measure the first center of gravity position and the second center of gravity position when the rotational angle around the pitch axis of the optical device  190  is at a second angle. 
     The optical device  190  can be detachable from the UAV body  101 . The optical device  190  can be rotatably held with the rotational axis of a direction different from the gravitational direction as the center. The rotational axis of a direction different from the gravitational direction can be the pitch axis. The measurement unit  180  can measure external force applied on the optical device  190  in a first state with the optical device  190  not mounted on the UAV body  101  and a second state with the optical device  190  mounted on the UAV body  101 . It can also measure the center of gravity position of the optical device  190  based on the external force in the first state and the external force in the second state. 
     In the UAV body  101 , the memory  106  can associate, and store, information that indicates the center of gravity position of the optical device  190 , having been measured by the measurement unit  180 , with identification information of the optical device  190 . The memory  106  is an example of a storage unit for associating, and storing, information that indicates the center of gravity position of the optical device  190  with identification information of the optical device  190 . The acquisition unit  170  can calculate the center of gravity position of the optical device  190  based on the center of gravity position indicated by the center of gravity position information stored in the memory  106  and associate it with identification information of the optical device  190  mounted to the UAV body  101 . 
     A memory  163  can store information that indicates at least one of the mass or the center of gravity position of the optical device  190 . The acquisition unit  170  can acquire information that indicates at least one of the mass or the center of gravity position of the optical device  190  from the optical device  190  mounted on the UAV body  101 . The memory  163  can store information that indicates an actual measured value of the center of gravity position of the optical device  190 . The acquisition unit  170  can acquire information that indicates an actual measured value of the mass and the center of gravity position of the optical device  190  from the optical device  190  mounted on the UAV body  101 . When the weight of the optical device  190  is known, the measurement unit  180  can calculate an output value of torque applied on the gimbal  110  in the initial state of the optical device  190 . The sum of the weight and the center of gravity position can be equal to the output value of torque. Therefore, the measurement unit  180  can calculate the center of gravity position when the optical device  190  is mounted to the UAV body  101  based on the output value of torque calculated by the measurement unit  180  and the weight of the optical device  190 . The initial state of the optical device  190  refers to when the optical device  190  is mounted to the UAV body  101 , and when power is applied to the optical device  190 . 
     The memory  163  can store information that indicates the mass and the center of gravity position of the optical device  190 . The acquisition unit  170  can acquire information that indicates the mass and the center of gravity position of the optical device  190  from the optical device  190  mounted on the control device. The acquisition unit  170  can acquire information that indicates the center of gravity position of the optical device  190  from the optical device  190  by communicating with the optical device  190  when the optical device  190  is mounted on the UAV body  101 . 
     When the optical device  190  is detachable from the control device, the memory  106  can associate the classification of a plurality of optical devices  190  with identifying classification information and store information that indicates at least one of the mass or the center of gravity position of the optical device  190  of each respective classification. The acquisition unit  170  can acquire information that indicates at least one of the mass or the center of gravity position stored in the memory  106  and associates it with classification information of the optical device  190  mounted on the UAV body  101 . 
     The gimbal control unit  112  can control the attitude of the optical device  190  based on a desired value of the attitude of the optical device  190 , a detected value of the attitude of the optical device  190 , and the attitude of the optical device  190  estimated based on the information acquired by the acquisition unit  170 . The gimbal control unit  112  can control the attitude of the optical device  190  by feedback information based on the detected value of the attitude of the optical device  190 , and a feed forward control based on information acquired by the acquisition unit  170 . 
       FIG. 3  illustrates when the optical device  190  is held in a reference attitude. As an example, the reference attitude can be such that the optical axis of the lens device  160  is approximately orthogonal to the gravitational direction. A reference attitude can be employed wherein the optical device  190  can be held at a predetermined pitch angle around the pitch axis. 
     The pitch axis drive motor  126  can generate holding torque T that holds the optical device  190 . The holding torque T can be applied to the optical device  190  via a pitch axis rotation mechanism. The optical device  190  can be held in a fixed attitude when the holding torque T balances with torque occurring due to gravity. 
     Gravity can act on the optical device  190  as an external force. It can be considered that gravity acts at a center of gravity position G of the optical device  190 . The size of torque occurring due to gravity can be hp×(m+M) for movement around the pitch axis of the optical device  190 . hp can be the distance from the pitch axis to the center of gravity position G. m can be the mass of the imaging unit  140 . M can be the mass of the lens device  160 . The relational expression T=hp×(m+M) can be fulfilled when the optical device  190  is held in a reference attitude by the holding torque T. 
     Mass information that indicates the mass M of the lens device  160  can be stored in the memory  163  of the lens device  160 . In the imaging unit  140 , the imaging control unit  142  can acquire information that indicates the mass M of the lens device  160  from the memory  163 . The acquisition unit  170  can communicate with the imaging control unit  142  and can acquire mass information of the lens device  160 . Mass information that indicates the mass m of the imaging unit  140  can be stored in the memory  106 . The acquisition unit  170  can acquire mass information of the imaging unit  140  from the memory  106 . The measurement unit  180  can acquire the holding torque T from the gimbal control unit  112 . The measurement unit  180  can calculate a distance h from the pitch axis to the center of gravity position G based on the relational expression relating to the holding torque T, the mass m of the imaging unit  140 , and the mass M of the lens device  160 . 
     The measurement unit  180  can measure the holding torque T for holding the optical device  190  in any combination of the zoom value and focus position of the lens device  160 . The measurement unit  180  can measure hp for an optional combination of the zoom value and focus position using the measurement of this holding torque T. 
     The gimbal control unit  112  can calculate a first operation signal based on the difference between a reference input signal and a feedback signal when controlling the pitch axis driver  116 . The gimbal control unit  112  can supply an operation signal to the pitch axis driver  116 . This operation signal can have a second operation signal added to the first operation signal. The reference input signal can be based on the desired value of the pitch angle. The feedback signal can be based on the detected value of the pitch angle. The second operation signal can be based on hp corresponding to the current zoom value and focus position of the lens device  160 , and the mass M+m of the optical device  190 . The second operation signal can indicate the attitude of the optical device  190  estimated based on hp and the mass M+m. As a result, the gimbal control unit  112  can control the pitch angle of the optical device  190  by feed forward control based on the center of gravity position of the optical device  190  and the mass of the optical device  190 . 
     The center of gravity position of the optical device  190  can dramatically change if the zoom value and focus position of the lens device  160  change. However, with the feedback control, the pitch angle of the optical device  190  can be suppressed from dramatically changing even if the center of gravity position of the optical device  190  dramatically changes. 
       FIG. 4  illustrates a distance hy from the yaw axis to the center of gravity position G. The distance hy is a function of hp and pitch angle θp. The distance hy is expressed as hy=hp×sine (θp). The measurement unit  180  can calculate hy in any θp based on the measured hp. 
     The gimbal control unit  112  can calculate the first operation signal based on the difference between the reference input signal and the feedback signal when controlling the yaw axis driver  114 . The gimbal control unit  112  can supply an operation signal to the pitch axis driver  116 . This operation signal can have the second operation signal added to the first operation signal. The reference input signal can be based on the desired value of the yaw angle. The feedback signal can be based on the detected value of the yaw angle. The second operation signal can be based on hy corresponding to the current zoom value and the current focus position of the lens device  160 , and the mass M+m of the optical device  190 . The second operation signal can indicate the attitude of the optical device  190  estimated based on hy and the mass M+m. As a result, the gimbal control unit  112  can control the yaw angle of the optical device  190  by feed forward control based on the center of gravity position of the optical device  190 , the mass of the optical device  190 , and the current pitch angle of the optical device  190 . 
     The center of gravity position of the optical device  190  can dramatically change if the zoom value and the focus position of the lens device  160  change. However, with the feedback control, the yaw angle of the optical device  190  can be suppressed from dramatically changing even if the center of gravity position of the optical device  190  dramatically changes. 
       FIG. 5  illustrates a format of first center of gravity position information stored in the memory  106  of the UAV body  101 . The first center of gravity position information can include a plurality of groups of zoom values, focus values, and hp data. The memory  106  can associate, and store the first center of gravity position information with a lens ID. The lens ID can be identification information that identifies the lens device  160 . 
       FIG. 6  illustrates a format of second center of gravity position information stored in the memory  106  of the UAV body  101 . The second center of gravity position information can include a plurality of groups of zoom values, focus values, pitch angles, and by data. The memory  106  can associate, and store, the second center of gravity position information with a lens ID. 
       FIG. 7  illustrates a format of third center of gravity position information that indicates a center of gravity position of the lens device  160 . The third center of gravity position information can include a plurality of groups of zoom values, focus values, and h L  data. h L  is, for example, the distance from a mounting face on the lens device  160  to the center of gravity position of the lens device  160 . The measurement unit  180  can calculate h L  using h L =hp−Lm. Lm can be the distance from the pitch axis to the mounting face on the imaging unit  140 . 
     The UAV control unit  104  can transmit the calculated third center of gravity position information to the lens device  160  via the imaging control unit  142 . In the lens device  160 , the lens control unit  162  can store this transmitted third center of gravity position information to the memory  163 . 
     When the third center of gravity position information has been stored in the memory  163 , the third center of gravity position information can be then supplied to the UAV control unit  104  via the lens control unit  162  and the imaging control unit  142  if the lens device  160  is mounted on the gimbal  110 . The acquisition unit  170  can calculate the center of gravity position of the lens device  160  using the acquired third center of gravity position information. The method for calculating the center of gravity position of the lens device  160  using the third center of gravity position information will be described in relation to  FIG. 8  and  FIG. 9 . 
       FIG. 8  illustrates when the lens device  160  is not mounted to the imaging unit  140 . The measurement unit  180  measures the distance from the pitch axis to the center of gravity position Gc of the imaging unit  140  using a method similar to the measurement method described in relation to  FIG. 3 . 
     The measurement unit  180  can acquire a holding torque T 0  from the gimbal control unit  112 . This holding torque T 0  can hold the imaging unit  140  in a reference attitude. As illustrated in  FIG. 8 , the relational expression T 0 =h p0 ×m is fulfilled. The measurement unit  180  can calculate h po  based on the mass m of the imaging unit  140  and the holding torque T 0 . 
       FIG. 9  illustrates a process for calculating hp from the center of gravity position of the lens device  160 . The measurement unit  180  can calculate hp using (−h p0 ×m+(h L +Lm)×M)/(m+M). As a result, the measurement unit  180  can calculate hp and hy corresponding to the plurality of groups of zoom values and focus values using the third center of gravity position information when the third center of gravity position information is stored in the lens device  160 . In such a case, the operation for holding the optical device  190  in a reference attitude and acquiring the holding torque T as described in relation to  FIG. 3  can be unnecessary. 
       FIG. 10  is a flowchart illustrating center of gravity position measurement procedures, in which hp and hy are measured. The process of this flowchart can be executed in parallel with initialization by the verification unit  188 . 
     At S 302 , the UAV control unit  104  can determine whether the third center of gravity position information of the lens device  160  is stored in the lens device  160 . When the third center of gravity position information is not stored in the lens device  160 , the acquisition unit  170  can acquire the mass M of the lens device  160  (S 304 ). The acquisition unit  170  can read the mass M stored in the memory  106  and associate it with a lens ID of the lens device  160 . 
     The process from S 306  to S 314  can be a loop process relating to a combination of zoom values and focus values of the lens device  160 . At S 308 , the UAV control unit  104  can control the gimbal control unit  112  and hold the optical device  190  at a reference attitude. This reference attitude can be the reference attitude illustrated in  FIG. 3 . At S 310 , the measurement unit  180  measures the holding torque T around the pitch axis. At S 312 , the measurement unit  180  can calculate hp, which indicates the center of gravity position. hp can be then calculated for each of the predetermined plurality of combinations of zoom values and focus values in the loop process from S 306  to S 314 . 
     At S 316 , the measurement unit  180  can calculate hy, which indicates the center of gravity position at the pitch angle θp. The method for calculating by can be based on the method described in  FIG. 4 , etc. 
     At S 318 , the UAV control unit  104  can store the first center of gravity position information to the memory  106  and associate it with a combination of zoom values and focus values. The UAV control unit  104  then can store the second center of gravity position information to the memory  106  associating it with a combination of zoom values, focus values, and pitch angles θp. 
     At S 320 , the measurement unit  180  can store the third center of gravity position information to the memory  163  of the lens device  160 . The operation of this flowchart can be completed when the process at S 320  is finished. 
     At the determination in S 302 , if the third center of gravity position information can be stored in the memory  163  of the lens device  160 , the acquisition unit  170  acquires it from the lens device  160  (S 330 ). The acquisition unit  170  can calculate the first center of gravity position information and the second center of gravity position information and store them to the memory  106  (S 332 ). The operation of this flowchart can be completed when the process at S 332  is finished. 
     With the UAV  100 , it is possible to control the attitude of the optical device  190  based on the actual measured value of the center of gravity position of the optical device  190 . As a result, control can be performed while considering individual differences between the lens device  160  and the imaging unit  140 . 
     The third center of gravity position information measured in the UAV  100  can be stored in the memory  163  of the lens device  160 . In a modified example, the third center of gravity position information can be information measured when manufacturing the lens device  160 . 
       FIG. 11  illustrates a format of fourth center of gravity position information stored in the UAV body  101  in another form. The memory  106  can store center of gravity position information including a plurality of groups of zoom value, focus value, and h L  data. The zoom values, focus values, and h L  can be all information similar to the third center of gravity position information described in relation to  FIG. 7 , etc. The fourth center of gravity position information can be center of gravity position information and associate it with the lens classification. In this aspect, the fourth center of gravity position information can differ from the third center of gravity position information. The fourth center of gravity position information can be information written to the memory  106  when the UAV  100  is manufactured. The memory  106  can store the fourth center of gravity position information and associate it with a classification ID that identifies the lens classification of the lens device  160 . 
     When the lens device  160  is mounted to the imaging unit  140 , the acquisition unit  170  can acquire the classification ID that identifies the classification of the lens device  160  from the lens device  160 . The acquisition unit  170  can acquire the fourth center of gravity position information stored in the memory  106  and associate it with the classification ID. The acquisition unit  170  can calculate the center of gravity position of the optical device  190  using the fourth center of gravity position information. The center of gravity position of the optical device  190  can be calculated using a process similar to the process described in relation to  FIG. 7  to  FIG. 9 . 
     The lens device  160  can be an interchangeable lens. However, the lens device  160  can be integrally provided with the imaging unit  140 . In such a case, the optical device  190  including the lens device  160  and the imaging unit  140  can be detachable from the gimbal  110 . 
     At least one step of the plurality of steps shown can be implemented by hardware or a program commanding related hardware. The program can be stored in a computer readable recording medium. The recording medium can include at least one of a ROM, magnetic disk, or optical disk. 
     The present disclosure was described using embodiments, but the technical scope of the disclosure is not limited to the scope in the above embodiments. It should be clear to a person skilled in the art that the above embodiments are susceptible to various modifications or improvements. It should also be clear from the scope of the claims that forms having such modifications or improvements can be included in the technical scope of the present disclosure. 
     The order of each process in the operations, procedures, steps, stages, etc., of the devices, systems, programs, and methods in the scope of the claims, specification, and drawings is not specifically disclosed using “beforehand”, “in advance”, etc., and any order is possible as long as a postprocess does not use the output of a preprocess. Even if “first,” “next”, etc., are used for convenience in describing the flow of operations in the scope of the claims, specification and drawings, it does not mean that it must be executed in this order. “Orthogonal” can also be “intersecting”. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
           100  UAV 
           101  UAV body 
           102  Communication interface 
           104  UAV control unit 
           105  Detection unit 
           106  Memory 
           107  Drive unit 
           108  Rotary wings 
           110  Gimbal 
           112  Gimbal control unit 
           114  Yaw axis driver 
           116  Pitch axis driver 
           118  Roll axis driver 
           124  Yaw axis drive motor 
           126  Pitch axis drive motor 
           128  Roll axis drive motor 
           130  Carrier 
           134  Yaw axis rotation mechanism 
           136  Pitch axis rotation mechanism 
           138  Roll axis rotation mechanism 
           140  Imaging unit 
           164  Lens 
           190  Optical device