Patent Publication Number: US-2018031074-A1

Title: Spatial stabilization apparatus and spatial stabilization method

Description:
TECHNICAL FIELD 
     The present disclosure relates to a spatial stabilization apparatus and a spatial stabilization method, and in particular to a spatial stabilization apparatus including a vibration suppression mechanism for preventing propagation of trembling and/or vibrations and a spatial stabilization method. 
     BACKGROUND ART 
     A spatial stabilization apparatus is an apparatus for stabilizing a pointing direction of a payload (an installed apparatus) such as a sensor, a camera, a communication antenna installed in a moving body such as an airplane, a vehicle, a ship, and an artificial satellite with respect to an inertial space even under a condition in which the pointing direction of the payload is affected by trembling and/or vibrations of the moving body. As a technique for improving the performance of such a spatial stabilization apparatus, a method in which a vibration suppression mechanism for preventing trembling and/or vibrations from propagating from an airframe is incorporated in a pointing mechanism for controlling the pointing direction of a payload has been known. For example, related techniques are disclosed in Patent Literature 1 to 6, etc. Note that trembling may be included in vibrations and vibrations may be included in trembling. 
       FIG. 11  shows a configuration of a related-art spatial stabilization apparatus (a vibration control mechanism for a pointing control apparatus)  900  disclosed in Patent Literature 1. As shown in  FIG. 11 , the related-art spatial stabilization apparatus  900  includes a vibration suppression unit  902  on which a pointing control apparatus  913  for controlling a direction of an installed apparatus  909  such as an antenna is placed and which is coupled to a fixed part  901  in such a manner that it can oscillate through a coil spring  903 , a plurality of noncontact-type actuators  904  which controls a position or an angle of the vibration suppression unit  902  with respect to the fixed part  901 , and a plurality of noncontact-type sensors  905  which measure a displacement, a speed, or an acceleration of the vibration suppression unit  902  with respect to the fixed part  901 . Further, the spatial stabilization apparatus  900  includes a displacement converter  906  which is implemented by using a digital signal processor (a DSP) and which performs a coordinate-transformation of a signal from each of the noncontact-type sensors  905  into a six-axis displacement, a compensator  907  which calculates six-axis control amounts from the coordinate-transformed six-axis displacements, and a distributer  908  which distributes the calculated six-axis control amounts to the respective noncontact-type actuators  904 , in which the position or the angle of the vibration suppression unit  902  with respect to the fixed part  901  is controlled. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Unexamined Patent Application Publication No. H10-132018 
     Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2009-19674 
     Patent Literature 3: Japanese Unexamined Patent Application Publication No. 2000-46977 
     Patent Literature 4: Japanese Unexamined Patent Application Publication No. H06-105189 
     Patent Literature 5: Japanese Unexamined Patent Application Publication No. H11-308604 
     Patent Literature 6: Japanese Unexamined Patent Application Publication No. 2004-205411 
     SUMMARY OF INVENTION 
     Technical Problem 
     The inventor of the present disclosure has found that there are cases in which vibrations cannot be sufficiently suppressed by the related technique such as the technique disclosed in Patent Literature 1. Specifically, when an installed apparatus is installed in a moving body, vibrations of the moving body are transferred to the installed apparatus and hence the installed apparatus vibrates. Depending on the frequency of the vibrations, the vibrations could lead to large shaking due to a resonance or the like. Therefore, it is necessary to suppress the vibrations transferred from the moving body as much as possible. 
     However, in the related technique, a predetermined transfer characteristic including a resonance frequency is used. Therefore, there is a problem that, depending on the frequency of occurring vibrations, there are cases in which the vibrations cannot be effectively suppressed. 
     In view of the above-described problem, an object of the present disclosure is to provide a spatial stabilization apparatus and a spatial stabilization method capable of effectively suppressing vibrations. 
     Solution to Problem 
     A spatial stabilization apparatus according to the present disclosure includes: a vibration suppression mechanism unit configured to suppress vibrations occurring in an installed apparatus installed in a moving body; an attitude angle detection unit configured to detect an attitude angle of the installed apparatus; a characteristic change unit configured to change a transfer characteristic of vibrations transferred from the moving body to the installed apparatus; and an attitude correction unit configured to control the vibration suppression mechanism unit based on the changed transfer characteristic so that the detected attitude angle is corrected. 
     A spatial stabilization method according to the present disclosure is a spatial stabilization method for controlling a vibration suppression mechanism unit configured to suppress vibrations occurring in an installed apparatus installed in a moving body, including: detecting an attitude angle of the installed apparatus; changing a transfer characteristic of vibrations transferred from the moving body to the installed apparatus; and controlling the vibration suppression mechanism unit based on the changed transfer characteristic so that the detected attitude angle is corrected. 
     Advantageous Effects of Invention 
     According to the present disclosure, it is possible to provide a spatial stabilization apparatus and a spatial stabilization method capable of effectively suppressing vibrations. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a configuration diagram showing an outline of a spatial stabilization apparatus according to an embodiment; 
         FIG. 2  is a schematic diagram schematically showing a moving body according to a first embodiment; 
         FIG. 3  is a configuration diagram showing a block configuration of a radar apparatus according to the first embodiment; 
         FIG. 4  is a configuration diagram showing a configuration of a spatial stabilization apparatus according to the first embodiment; 
         FIG. 5  is a configuration diagram showing a block configuration of a control unit according to the first embodiment; 
         FIG. 6  is a flowchart showing an operation of the spatial stabilization apparatus according to the first embodiment; 
         FIG. 7  is a graph showing a vibration characteristic of the spatial stabilization apparatus according to the first embodiment; 
         FIG. 8  is a configuration diagram showing a configuration of a spatial stabilization apparatus according to a second embodiment; 
         FIG. 9  is a graph showing a filter characteristic of the spatial stabilization apparatus according to the second embodiment; 
         FIG. 10A  is a waveform diagram showing an example of a signal of the spatial stabilization apparatus according to the second embodiment; 
         FIG. 10B  is a waveform diagram showing an example of a signal of the spatial stabilization apparatus according to the second embodiment; and 
         FIG. 11  is a Cited Document diagram showing a configuration of a spatial stabilization apparatus in related art. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Outline of Embodiment 
       FIG. 1  shows an example of an outline of a spatial stabilization apparatus  10  according to this embodiment. As shown in  FIG. 1 , the spatial stabilization apparatus  10  includes an installed apparatus  13  installed in a moving body  11 , a vibration suppression mechanism unit  12  that suppresses vibrations occurring in the installed apparatus  13 , and an attitude angle detection unit  14  that detects an attitude angle of the installed apparatus  13 . The spatial stabilization apparatus  10  further includes a characteristic change unit  15  that changes a transfer characteristic of vibrations transferred from the moving body  11  to the installed apparatus  13 , and an attitude correction unit  16  that controls the vibration suppression mechanism unit  12  based on the changed transfer characteristic so that the detected attitude angle is corrected. 
     By changing the transfer characteristic of vibrations and controlling the vibration suppression mechanism unit as described above, it is possible to cope with various types of vibrations and thereby effectively suppress vibrations. 
     First Embodiment 
     A first embodiment is explained hereinafter with reference to the drawings. In this embodiment, an example in which in a moving body with a radar apparatus installed therein, vibration suppression control for an antenna of the radar apparatus is performed is explained. 
       FIG. 2  schematically shows a moving body  30  according to this embodiment. The moving body  30  according to this embodiment is an airplane, a vehicle, a ship, an artificial satellite, or the like. For example, the moving body  30  is a small airplane or a helicopter. The moving body  30  includes a radar apparatus  100  installed therein, and observes a state of the earth&#39;s surface or the like while traveling. As an example, the radar apparatus  100  may be an SAR (Synthetic Aperture Radar). The SAR reproduces an observation image from data (complex data) on an amplitude and a phase of a received wave obtained through an antenna based on a position/attitude of the antenna (i.e., the moving body) and thereby reads the state of the earth&#39;s surface. Note that since the SAR is used, it is necessary to suppress trembling and/or vibrations, in particular, trembling and/or vibrations of the antenna. Note that the radar apparatus  100  is not limited to the SAR and may be other radars such as a search radar. 
     The radar apparatus  100  includes, as main components, an antenna unit  101  including an antenna, and a signal processing unit  102  that performs signal processing for a radio wave transmitted/received by the antenna. For example, the antenna unit  101  is disposed in a lower part of an airframe  31  of the moving body  30  and emits a radio wave from the antenna toward the earth&#39;s surface located below the airframe  31 . The signal processing unit  102  is disposed inside the airframe  31  of the moving body  30  and displays an observation image observed through the antenna in real time. 
       FIG. 3  shows functional blocks of the radar apparatus  100  according to this embodiment. As shown in  FIG. 3 , the radar apparatus  100  according to this embodiment includes a transmission unit  110 , a reception unit  111 , an image processing unit  112 , a circulator  113 , a control unit  120 , an antenna  201 , an antenna driving mechanism  202 , a vibration suppression mechanism  203 , and an antenna sensor  103 . For example, the antenna unit  101  may include the antenna  201 , the antenna driving mechanism  202 , the vibration suppression mechanism  203 , and the antenna sensor  103 . Further, the signal processing unit  102  may include the transmission unit  110 , the reception unit  111 , the image processing unit  112 , the circulator  113 , and the control unit  120 . 
     The transmission unit  110  generates a transmission signal for carrying out an observation by using an SAR. The circulator  113  transmits the transmission signal generated by the transmission unit  110  from the antenna  201  and outputs a reception signal received by the antenna  201  to the reception unit  111 . The antenna driving mechanism  202  drives the antenna  201  so that the antenna  201  has an optimal direction and an optimal position according to control by the control unit  120 . The antenna  201  transmits a transmission wave (i.e., a transmission signal) to an object to be observed and receives a reception wave (i.e., a reception signal) reflected on the object to be observed. The vibration suppression mechanism  203  suppresses trembling and/or vibrations occurring in the antenna  201  according to control by the control unit  120 . 
     The antenna sensor  103  detects an amount of displacement of the antenna  201 , which has been displaced according to the driving of the antenna driving mechanism  202 , and detects trembling and/or vibrations of the antenna  201 . The antenna sensor  103  is an attitude angle sensor that detects an attitude angle of the antenna  201 . Alternatively, the antenna sensor  103  may be a GPS (Global Positioning System), a speed sensor, an acceleration sensor, a gyroscopic sensor, a resolver, a displacement sensor, a rate sensor, or the like. 
     The reception unit  111  performs signal processing for the reception signal received by the antenna  201  and thereby generates a signal that the image processing unit  112  can process. The image processing unit  112  performs image processing for the reception signal processed by the reception unit  111 , detects an object to be observed, generates an observation image, and displays the generated observation image. 
     The control unit  120 , which is a control unit that controls each unit of the radar apparatus, controls the antenna driving mechanism  202 , the vibration suppression mechanism  203 , and so on based on the detection result of the antenna sensor  103  and the observation result of the image processing unit  112 . The control unit  120  is an antenna driving control unit that controls the driving of the antenna driving mechanism  202 , and also serves as a vibration suppression control unit that controls a vibration suppression operation performed by the vibration suppression mechanism  203 . 
     For example, in the case of a spotlight mode in which a specific object to be observed is observed, the control unit  120  controls the antenna driving mechanism  202  so that a radio wave is emitted from a flight path toward the object to be observed all the time. Further, in the case of a strip-map mode in which an area along a flight path is observed, the control unit  120  controls the antenna driving mechanism  202  so that a radio wave is emitted to the flight path at a specific angle. In this embodiment, the control unit  120  changes a transfer characteristic including a resonance frequency of vibrations and controls the vibration suppression mechanism  203  based on the changed transfer characteristic. 
     A spatial stabilization apparatus  20  according to this embodiment is an apparatus that stabilizes the attitude of the antenna  201  against trembling and vibrations of the moving body  30 , and includes, for example, the antenna  201 , the antenna driving mechanism  202 , the vibration suppression mechanism  203 , the antenna sensor  103 , and the control unit  120 . 
       FIG. 4  shows a configuration example of the spatial stabilization apparatus  20  according to this embodiment. As shown in  FIG. 4 , the antenna driving mechanism  202  is a bi-axial gimbal mechanism for rotationally driving the antenna  201  around two axes. The antenna driving mechanism  202  rotationally drives the antenna  201  around an EL (elevation) axis and an AZ (azimuth) axis according to control by the control unit  120 . The AZ axis is perpendicular to the trajectory of the moving body  30  and the EL axis is perpendicular to the AZ axis. For example, the antenna sensor  103  is disposed on the bottom (in a base part) of the antenna driving mechanism  202  and detects the attitudes of the antenna  201  and the antenna driving mechanism  202 . The antenna sensor  103  may be directly mounted on the antenna  201 . 
     The vibration suppression mechanism  203  is disposed between the airframe  31  and an assembled unit of the antenna driving mechanism  202  and the antenna  201 , and supports the antenna driving mechanism  202  and the antenna  201 . When the airframe  31  vibrates (Δx), the vibrations are transferred and hence the antenna driving mechanism  202  and the antenna  201  vibrate (Δy). The vibration suppression mechanism  203  suppresses the vibrations (Δy) that occur in the antenna driving mechanism  202  and the antenna  201  according to the transfer of the vibrations (Δx) of the airframe  31 . 
     The vibration suppression mechanism  203  is an active vibration suppression apparatus and includes a vibration suppression spring  211  and a vibration suppression actuator  212 . One end of the vibration suppression spring  211  is fixed to the airframe  31  and the other end is fixed to the antenna driving mechanism  202  (and the antenna  201 ). For example, the bottom of the antenna driving mechanism  202  has a circular shape in a plan view and a plurality of vibration suppression springs  211  are arranged near the outer circumference of the bottom of the antenna driving mechanism  202  so that the antenna driving mechanism  202  is supported in a well-balanced manner. The vibration suppression springs  211  suppress vibrations that are transferred from the airframe  31  to the antenna driving mechanism  202  and the antenna  201  by elasticity corresponding to their spring constant. 
     Similarly to the vibration suppression spring  211 , one end of the vibration suppression actuator  212  is fixed to the airframe  31  and the other end is fixed to the antenna driving mechanism  202  (and the antenna  201 ). For example, a plurality of vibration suppression actuators  212  are arranged near the outer circumference of the bottom of the antenna driving mechanism  202  so that they correspond to the plurality of vibration suppression springs  211 . The vibration suppression actuators  212  are driven according to control of the control unit  120  and generate a vibration suppression force for suppressing vibrations of the antenna  201 . The vibration suppression force is a reactive force that acts in an opposite direction to the direction of the vibration transferred from the airframe  31  to the antenna  201 . 
     The control unit  120  includes a characteristic change unit  121  and an attitude correction unit  122 . Note that other configurations may be used, provided that a vibration suppression operation (a spatial stabilization method) according to this embodiment can be realized. The characteristic change unit  121  changes a characteristic (a transfer characteristic) of vibrations that transferred from the airframe  31  to the antenna  201  and hence occur in the antenna  201 . In this embodiment, the characteristic change unit  121  controls the driving of the vibration suppression actuator  212  so that the resonance frequency and/or the peak value of vibrations are changed. 
     The attitude correction unit  122  controls the driving of the vibration suppression actuator  212  so that vibrations of the antenna  201  detected by the antenna sensor  103  are corrected by the changed characteristic (the transfer characteristic) of the vibrations. For example, the attitude correction unit  122  drives the vibration suppression actuator  212  according to a signal (a value) that is obtained by adding a detection result of the antenna sensor  103  to a target attitude angle of the antenna  201 . 
       FIG. 5  shows a more specific configuration example of the control unit  120  included in the spatial stabilization apparatus  20  according to this embodiment. As shown in  FIG. 5 , the control unit  120  includes, for example, a sensor processing unit  130 , a control calculation unit  140 , and a driver unit  150 . Note that the sensor processing unit  130 , the control calculation unit  140 , and the driver unit  150  may be configured as one block or may be divided into an arbitrary number of blocks. 
     It can also be considered that the sensor processing unit  130  and the control calculation unit  140  constitute a control unit that generates a driving signal(s) (a drive command value(s)) for driving the antenna driving mechanism  202  and the vibration suppression mechanism  203 . 
     The sensor processing unit  130  processes the detection signal detected by the antenna sensor  103 . For example, the sensor processing unit  130  includes a noise reduction unit  131  and a coupled control calculation unit  132 . The noise reduction unit  131  removes noises from the detection signal detected by the antenna sensor  103 . For example, the noise reduction unit  131  is a low-pass filter or the like. 
     The coupled control calculation unit  132  performs a coordinate conversion and/or a target value calculation necessary for driving the antenna driving mechanism  202  and the vibration suppression mechanism  203  based on the detection signal of the antenna sensor  103 . The target value calculation is preferably performed so that the antenna driving mechanism  202  and the vibration suppression mechanism  203  are both controlled in a coupled manner (a corresponding manner), rather than making them operate independently of each other. In particular, for the vibration suppression control, a target value is generated while incorporating the attitude of the bi-axial gimbal (the attitude in the AZ and EL directions) into the calculation. 
     The coupled control calculation unit  132  determines the target value based on an observation mode, an attitude and an amount of movement of the airframe, an attitude and an amount of displacement of the antenna, and so on. The coupled control calculation unit  132  generates an AZ (azimuth) target angle, an AZ angle, and an AZ angular speed as AZ control parameters, generates an EL (elevation) target angle, an EL angle, and an EL angular speed as EL control parameters, and generates a vibration suppression target value and a vibration suppression control amount as vibration suppression control parameters. For example, it can be considered that the output of the coupled control calculation unit  132  corresponds to a signal (a value), shown in  FIG. 4 , that is obtained by combining the target attitude angle and the antenna sensor  103 . 
     The control calculation unit  140  performs control by using PID (Proportional Integral Derivative) controller, a phase lead/delay controller, an optimal controller, and so on so that detected values follow the respective target values. The control calculation unit  140  includes an AZ control unit  141 , an EL control unit  142 , and a vibration suppression control unit  143 . 
     The AZ (azimuth) control unit  141  generates an AZ drive command value for driving the antenna  201  in an azimuth direction based on the input AZ target angle, the AZ angle, and the AZ angular speed so that the antenna  201  moves to the AZ target angle. The EL (elevation) control unit  142  generates an EL drive command value for driving the antenna  201  in an elevation direction based on the input EL target angle, the EL angle, and the EL angular speed so that the antenna  201  moves to the EL target angle. 
     The vibration suppression control unit  143  generates a vibration suppression command value for performing vibration suppression driving of the antenna  201  based on the input vibration suppression target value and the vibration suppression control amount so that the antenna  201  moves to the vibration suppression target value. For example, it can be considered that the vibration suppression control unit  143  corresponds to the characteristic change unit  121  and the attitude correction unit  122  shown in  FIG. 4 . 
     The driver unit  150  generates a driving signal for driving the antenna driving mechanism  202  and the vibration suppression mechanism  203 . The driver unit  150  includes a motor driver  151  and a vibration suppression driver  152 . The motor driver  151  is a drive unit for driving the antenna driving mechanism  202 . 
     The motor driver  151  generates an AZ driving voltage based on the input AZ drive command value and supplies the generated AZ driving voltage to the antenna driving mechanism  202  (a motor for azimuth). The motor driver  151  generates an EL driving voltage based on the input EL drive command value and supplies the generated EL driving voltage to the antenna driving mechanism  202  (a motor for elevation). 
     The vibration suppression driver  152  is a drive unit for driving the vibration suppression mechanism  203 . The vibration suppression driver  152  generates a vibration suppression driving voltage for driving the antenna  201  based on the input vibration suppression command value and supplies the generated vibration suppression driving voltage to the vibration suppression actuator  212  of the vibration suppression mechanism  203 . 
     Next, a vibration suppression operation (a spatial stabilization method) according to this embodiment is explained with reference to  FIGS. 6 and 7 . Note that the operation explained below is explained on the assumption that the operation is mainly performed by the characteristic change unit  121  and the attitude correction unit  122 . However, the operation may be implemented by an arbitrary configuration in the control unit  120 . 
     As shown in  FIG. 6 , the characteristic change unit  121  of the control unit  120  acquires a transfer characteristic (S 101 ) and changes the acquired transfer characteristic (S 102 ). 
     For example, the characteristic change unit  121  acquires a transfer characteristic  300  as shown in  FIG. 7 . The transfer characteristic indicates transfer ratio Δy/Δx of vibrations versus frequency of the vibrations. The characteristic change unit  121  may acquire information on a characteristic that is stored in advance in a storage unit or the like, or determine a characteristic according to the configuration of the moving body  30 , the vibration suppression mechanism  203 , the antenna  201 , and so on. For example, the transfer characteristic (the transfer function) may be specified based on the spring constant of the vibration suppression spring  211  of the vibration suppression mechanism  203 . 
     The characteristic change unit  121  changes the acquired transfer characteristic  300  to transfer characteristics  301  to  303 . The characteristic change unit  121  may change the transfer characteristic to one of the transfer characteristics  301  to  303 , or may change the transfer characteristic to a characteristic that is obtained by combining the transfer characteristics  301  to  303 . For example, the characteristic change unit  121  changes the characteristic by changing a parameter of the transfer function. 
     In the example of the transfer characteristic  301 , control is performed so that a peak value at a resonance frequency f 1  is lowered. In the case of the transfer characteristic  301 , it is possible to prevent the largest vibration from occurring. In the example of the transfer characteristic  302 , control is performed so that the resonance frequency f 1  is lowered to a resonance frequency f 2 . In the case of the transfer characteristic  302 , it is possible to prevent vibrations having frequencies higher than the resonance frequency f 2  from occurring by lowering the resonance frequency to the resonance frequency f 2 . In the example of the transfer characteristic  303 , control is performed so that the characteristic in frequencies lower than the resonance frequency f 1  is lowered. In the case of the transfer characteristic  303 , it is possible to prevent vibrations from occurring at the start of shaking. 
     Next, the antenna sensor  103  detects the attitude of the antenna (S 103 ) and the attitude correction unit  122  of the control unit  120  corrects the attitude of the antenna (S 104 ). The attitude correction unit  122  performs control so that the attitude of the antenna  201  is corrected by the transfer characteristic that has been changed as shown in  FIG. 7 . 
     As described above, in this embodiment, the attitude of the antenna mounted on the moving body is corrected by changing the transfer characteristic for the vibration suppression mechanism for the antenna. In this way, vibrations can be suppressed more effectively compared to the case where the transfer characteristic is fixed. It is possible to considerably suppress vibrations that are transferred from the moving body to the antenna by changing the peak value of the transfer characteristic, the resonance frequency, and/or the transfer ratio in a low-frequency band. Vibrations are different depending on the moving body. For example, while a large airplane vibrates slowly with a long period, a small airplane or a helicopter vibrates quickly with a short period. It is possible to suppress such various types of vibrations by changing the transfer characteristic as explained in this embodiment. 
     Second Embodiment 
     A second embodiment is explained hereinafter with reference to the drawings. In this embodiment, an example in which vibration suppression control is performed based on an active attitude change in addition to the vibration suppression control in the first embodiment is explained. 
       FIG. 8  shows a configuration of a spatial stabilization apparatus  20  according to this embodiment. As shown in  FIG. 8 , the spatial stabilization apparatus  20  includes an airframe sensor  104  and an active attitude change extraction unit  160  in addition to the configuration of the first embodiment. The rest of the configuration is similar to that of the first embodiment. 
     The airframe sensor  104  is disposed in the airframe  31  and detects the attitude (displacements in roll, pitch and yaw) of the airframe  31 , vibrations thereof, and so on. Similarly to the antenna sensor  103 , the airframe sensor  104  is an attitude angle sensor. For example, the airframe sensor  104  may be a GPS, a speed sensor, an acceleration sensor, a gyroscopic sensor, a resolver, a displacement sensor, a rate sensor, or the like. 
     The active attitude change extraction unit  160  extracts an active attitude change from the attitude angle of the moving body and sets (adds) this extracted active attitude change in the target attitude angle of the vibration suppression mechanism. The active attitude change means a large active change in the attitude of a moving body that occurs when the moving body changes its trajectory such as when it turns in the horizontal direction or in the vertical direction. Further, the active attitude change does not include any change caused by vibrations or trembling. For example, the active attitude change extraction unit  160  can be formed by using a low-pass filter. 
       FIG. 9  is an example of a frequency characteristic of a low-pass filter which serves as the active attitude change extraction unit  160 . The active attitude change extraction unit  160  cuts off signals having frequencies higher than a cut-off frequency fc and lets signals having frequencies lower than the cut-off frequency fc pass therethrough. In order to remove vibration components of the airframe  31 , the cut-off frequency fc is set to a frequency lower than the frequency of vibrations of the airframe  31 . 
     For example, the airframe sensor  104  generates a detection signal shown in  FIG. 10A  and supplies the generated detection signal to the low-pass filter, which serves as the active attitude change extraction unit  160 . As shown in  FIG. 10A , the detection signal includes high-frequency vibration components. For example, the moving body repeats an observation by using a radar device and a turning action. The moving body has a constant attitude in the observation and its attitude considerably rolls in the turning action. Then, the active attitude change extraction unit  160  removes high-frequency vibration components from the detection signal by using the low-pass filter and thereby generates an attitude change extraction signal shown in  FIG. 10B . 
     In  FIG. 8 , the detection signal detected by the antenna sensor  103  and the position change extraction signal extracted by the active attitude change extraction unit  160  are added to the target attitude angle and the resultant signal is input to the control unit  120 . The control unit  120  controls the vibration suppression mechanism  203  based on the detection signal detected by the antenna sensor  103  and the position change extraction signal extracted by the active attitude change extraction unit  160 . 
     In the related technique, only the target attitude angle of the vibration suppression mechanism is supplied in advance. Therefore, there is a problem that when the attitude angle of the moving body considerably changes due to the change in the trajectory or the like, the attitude angle of the vibration suppression mechanism becomes unstable and/or the attitude angle gets closer to the limit of the operating range. 
     Therefore, this embodiment includes means for detecting an attitude angle of a moving body and means for extracting an active attitude change from the attitude angle of the moving body, and the attitude angle extracted by this extraction means is set (added) in the target attitude angle of the vibration suppression mechanism. 
     In this way, at the time of an active attitude change of the moving body such as a change in the trajectory, the correction is made so as to follow this attitude change. Therefore, it is possible to prevent propagation of trembling/vibrations without making the attitude angle of the vibration suppression mechanism unstable. Therefore, it is possible to stabilize the pointing direction of a payload with respect to an inertial space throughout the entire moving path including a trajectory change. 
     Note that the present disclosure is not limited to the above-described embodiments and can be modified as appropriate without departing from the spirit and scope of the present disclosure. 
     For example, in the above-described embodiment, an example in which vibrations of an antenna mounted on a moving body are suppressed is explained. However, vibrations of other installed apparatuses installed in the moving body such as a sensor or a camera may be suppressed. 
     Each structure in the above-described embodiment may be constructed by software, hardware, or both of them. Further, each structure may be constructed by one hardware device or one software program, or a plurality of hardware devices or a plurality of software programs. Each function (each process) in the embodiment may be implemented by a computer including a CPU, a memory, and so on. For example, a control program for performing a control method according to the embodiment may be stored in a storage device (a storage medium) and each function may be implemented by having a CPU execute the control program stored in the storage device. 
     Although the present disclosure is explained above with reference to embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. 
     This application is based upon and claims the benefit of priority from Japanese patent applications No. 2015-033903, filed on Feb. 24, 2015, the disclosure of which is incorporated herein in its entirety by reference. 
     REFERENCE SIGNS LIST 
       10  SPATIAL STABILIZATION APPARATUS 
       11  MOVING BODY 
       12  VIBRATION SUPPRESSION MECHANISM UNIT 
       13  INSTALLED APPARATUS 
       14  ATTITUDE ANGLE DETECTION UNIT 
       15  CHARACTERISTIC CHANGE UNIT 
       16  ATTITUDE CORRECTION UNIT 
       20  SPATIAL STABILIZATION APPARATUS 
       30  MOVING BODY 
       31  AIRFRAME 
       100  RADAR APPARATUS 
       101  ANTENNA UNIT 
       102  SIGNAL PROCESSING UNIT 
       103  ANTENNA SENSOR 
       104  AIRFRAME SENSOR 
       110  TRANSMISSION UNIT 
       111  RECEPTION UNIT 
       112  IMAGE PROCESSING UNIT 
       113  CIRCULATOR 
       120  CONTROL UNIT 
       121  CHARACTERISTIC CHANGE UNIT 
       122  ATTITUDE CORRECTION UNIT 
       130  SENSOR PROCESSING UNIT 
       131  NOISE REDUCTION UNIT 
       132  COUPLED CONTROL CALCULATION UNIT 
       140  CONTROL CALCULATION UNIT 
       141  AZ (AZIMUTH) CONTROL UNIT 
       142  EL (ELEVATION) CONTROL UNIT 
       143  VIBRATION SUPPRESSION CONTROL UNIT 
       150  DRIVER UNIT 
       151  MOTOR DRIVER 
       152  VIBRATION SUPPRESSION DRIVER 
       160  ACTIVE ATTITUDE CHANGE EXTRACTION UNIT 
       201  ANTENNA 
       202  ANTENNA DRIVING MECHANISM 
       203  VIBRATION SUPPRESSION MECHANISM 
       211  VIBRATION SUPPRESSION SPRING 
       212  VIBRATION SUPPRESSION ACTUATOR