JP4535187B2 - Antenna attitude control device - Google Patents

Description

  The present invention relates to an antenna attitude control device that is mounted on a moving body such as a ship and performs polarization angle control of a satellite communication antenna that tracks a satellite.

  In a communication terminal station that is mounted on a mobile body such as a ship and communicates via a communication satellite, the attitude of the communication antenna installed on the mobile body is controlled in accordance with the movement of the mobile body to constantly track the satellite. Therefore, it is necessary to secure and maintain the communication line with the best directivity of radio waves with the satellite. Further, in such antenna tracking control, in order to obtain a better antenna gain, it is also necessary to control the antenna polarization direction with respect to the polarization angle of the radio wave from the satellite. For this reason, a technique has been proposed in which the polarization angle can be controlled in the attitude control of the satellite tracking antenna mounted on the mobile body (see, for example, Patent Document 1).

  In the antenna attitude control technique described in Patent Document 1, a coordinate transformation matrix between the moving body coordinates and the earth coordinates is calculated from the angular velocity component of the movement of the moving body detected using the angular velocity detecting means, and the acceleration detecting means is used. The drift component of the coordinate transformation matrix is removed based on the acceleration component of the moving body motion detected in this way and the orientation of the moving body detected using the geomagnetic azimuth compass or gyrocompass, and the command orientation that the antenna should take in the earth coordinate system Command attitude matrix consisting of angle, command elevation angle, and command polarization angle is determined, and command attitude matrix is converted to antenna attitude matrix on moving body coordinates using coordinate conversion matrix, and based on element components of antenna attitude matrix Thus, the attitude of the antenna mounted on the moving body is controlled.

JP-A-7-79111

  In the antenna attitude control technique described in Patent Document 1, a geomagnetic azimuth compass or gyrocompass mounted on a moving body is used to detect the azimuth of the moving body. When tracking the satellite, the direction detection value of the moving body is used as described later for the calculation of the polarization angle control component for adjusting the antenna polarization direction to the satellite polarization direction. When an error is included, it appears as an error of the polarization angle component to be controlled. The error of the polarization angle control value depends on the satellite elevation angle, and diverges as the satellite elevation angle decreases. For this reason, as the elevation angle of the satellite to be tracked becomes smaller, the polarization angle control error due to the error included in the azimuth detection value becomes larger, and there is a problem that the cross polarization identification degree of the antenna decreases.

  The present invention has been made to solve the above-described problems, and can control the polarization angle control error to be small regardless of the elevation angle of the satellite, thereby preventing the cross polarization discrimination of the antenna from being lowered. An object is to obtain an antenna attitude control device.

  According to a first aspect of the present invention, there is provided an antenna attitude control device based on a position detection unit that detects a position of a moving body, a position detection value of the moving body detected by the position detection unit, and satellite position information. A satellite direction calculation unit that calculates the satellite direction viewed from the position of the satellite, an azimuth detection unit that detects the azimuth of the moving body, a sway detection unit that detects a sway of the mobile body with respect to the horizontal plane, and a satellite elevation angle equal to or greater than a predetermined value Calculates the attitude of the moving body based on the direction detection value detected by the direction detection means, and when the satellite elevation angle is a predetermined value or less, the attitude of the moving body is calculated based on the shake detection value detected by the movement detection means. A polarization angle calculation that calculates the polarization angle of the radio wave from the satellite based on the attitude calculation unit that calculates the angle, the attitude of the moving body calculated by the attitude calculation unit, and the satellite direction calculated by the satellite direction calculation unit When, in which a polarization angle adjusting means for adjusting the polarization angle of the antenna based on the polarization angle calculated by the polarization angle calculator.

  According to a second aspect of the present invention, there is provided an antenna attitude control device based on a position detection means for detecting a position of a mobile body, a position detection value of the mobile body detected by the position detection means, and satellite position information. A satellite direction calculation unit that calculates the satellite direction viewed from the position of the satellite, a tracking control unit that controls the tracking of the antenna in the satellite direction, an azimuth detection unit that detects the azimuth of the moving body, and detects the movement of the moving body with respect to the horizontal plane The moving direction detection means, the satellite direction calculated from the position of the moving object calculated by the satellite direction calculation unit, the pointing direction of the antenna controlled by the tracking control unit in the fixed fixed reference coordinate system, and the satellite elevation angle are predetermined. When the value is greater than or equal to the value, the direction detection value detected by the direction detection means or when the satellite elevation angle is less than or equal to a predetermined value, the movement is detected based on the motion detection value detected by the motion detection means. Based on the attitude calculation unit for calculating the attitude of the body, the attitude of the moving object calculated by the attitude calculation unit, and the satellite direction calculated by the satellite direction calculation unit, the polarization angle of the radio wave from the satellite is calculated. A polarization angle calculation unit and polarization angle adjustment means for adjusting the polarization angle of the antenna based on the polarization angle calculated by the polarization angle calculation unit are provided.

  According to the present invention, in the calculation of the attitude of the moving object, the direction detection value of the moving object is obtained when the satellite elevation angle is greater than or equal to a predetermined value, and when the satellite elevation angle is less than or equal to the predetermined value, Since the detection value is used, the error of the polarization angle can be suppressed regardless of the elevation angle of the satellite, and the influence of the cross polarization component can be suppressed.

Embodiment 1 FIG.
1 is a block diagram showing a functional configuration of an antenna attitude control apparatus according to Embodiment 1 of the present invention. Basic attitude control of the satellite tracking antenna is performed by the antenna shaft drive control unit 13 in the drive control unit 2 changing the antenna directing direction (direction toward the antenna mirror surface 1) in accordance with an instruction from the tracking control unit 3. . The tracking control unit 3 uses the drive control method such as the conical scan method or the step track method for the antenna axis to generate an antenna angle command value so that the intensity of the received wave from the satellite becomes larger, and the generated antenna angle The command value is commanded to the antenna shaft drive control unit 11 and tracking control is performed so that the antenna directivity direction faces the satellite direction. The antenna drive control is simply performed by monitoring the angle of the antenna shaft output from the angle detector provided on the antenna shaft and driving the drive motor provided on the antenna shaft so as to follow the antenna angle command value. However, when the moving body is moving rapidly, an angular velocity sensor is provided on the antenna shaft, etc., motion compensation is performed using the angular velocity information of the antenna output from this angular velocity sensor, and the drive control in the antenna pointing direction is further improved. Try to stabilize.

  The position detection means 4 detects the current position (latitude, longitude) of the moving body by GPS (Global Positioning System) or the like, and gives the position detection value to the satellite direction calculation unit 5. The satellite direction calculation unit 5 is viewed from the antenna position (that is, the moving object) from the position detection value of the moving object acquired by the position detecting means 4 and the position (latitude, longitude, altitude) information of the tracking target satellite. Calculate the satellite direction. When the moving body is an aircraft, the current position of the moving body includes the altitude. In the attitude calculation unit 6, the satellite direction (direction in an LLN coordinate system described later) calculated by the satellite direction calculation unit 5 and the antenna pointing direction (fixed to a moving body described later) obtained as a result of tracking control by the tracking control unit 3. The orientation of the moving object (roll angle, pitch angle, yaw angle) based on the orientation detection value detected by the orientation detection means 7 or the motion detection value detected by the motion detection means 8. To do. The selection unit 9 switches the direction detection value and the shake detection value according to the magnitude of the satellite elevation angle in the satellite direction, and gives it to the attitude calculation unit 6. Here, the azimuth detecting means 7 is a device suitable for measuring the azimuth of a moving body, such as a magnetic azimuth sensor or a gyrocompass, and the sway detecting means 8 is a sway of the horizontal plane of the moving body such as an inclinometer or an inertial navigation device. It is a device suitable for detection. The polarization angle calculation unit 10 calculates the polarization angle of the radio wave from the satellite based on the attitude of the moving body calculated by the attitude calculation unit 6 and the satellite direction calculated by the satellite direction calculation unit 5. And is given to the antenna polarization angle drive control unit 12 in the drive control unit 2. The antenna polarization angle drive control unit 12 adjusts the polarization angle of the antenna so that the polarization angle of the given antenna is obtained. The polarization angle adjustment of the antenna includes a drive mechanism that mechanically rotates the antenna around its directivity direction and drives the drive mechanism, or a polarization converter that rotates two orthogonal axes of the received radio wave. Can also be done.

  Next, a method for calculating the posture of the moving body in the posture calculation unit 6 will be described. First, the coordinate system will be described. As shown in FIG. 2, the moving body fixed coordinate system is configured such that the nose direction of the moving body is the x-axis, the bottom direction of the moving body is the z-axis, and the x-axis and the z-axis constitute a right-handed system. This is a coordinate system with the y axis taken along the axis. In addition, the LLN (Local Level North) coordinate system of the moving body is a right-handed system composed of the moving body position as the origin, the true north direction as the X axis, the earth center direction as the Z axis, and the X axis and the Z axis. Thus, the coordinate system takes the Y axis. The coordinate transformation from the vector U of the LLN coordinate system of the moving body to the vector u of the moving body fixed coordinate system is performed using the roll angle ψ, the pitch angle θ, and the yaw angle φ, which are the posture angles of the moving body, as follows: It is done as follows.

First, a case will be described in which the orientation of the moving object is calculated using the detected direction value of the moving object as a known amount. The antenna directing direction is tracking-controlled in a direction in which the intensity of the received wave from the satellite becomes larger and directs the satellite direction. The antenna polarization angle is calculated by the following method and output as an antenna polarization angle command value, and is adjusted and controlled by the antenna polarization angle drive control unit in an open loop. Input from the azimuth detecting means 7, which is a known quantity, the satellite direction vector P of the LLN coordinate system calculated from the position of the moving body and the satellite position, the antenna directing direction vector Q (satellite direction vector in the moving body fixed coordinate system) from which azimuth detection value (yaw angle) phi _t, and the orientation of the moving body is calculated by calculating a roll angle [psi _S and the pitch angle theta _S of the moving object is unknown amount. Then, using the azimuth detection value, the obtained roll angle and pitch angle, the satellite polarization direction vector R of the LLN coordinate system calculated from the position of the moving body, the satellite position, and the polarization angle information of the satellite is coordinate-transformed. Then, the satellite polarization direction vector T in the movable body fixed coordinate system is calculated. Using this vector, a command value for the antenna polarization angle is calculated, and the antenna polarization angle is adjusted and controlled in that direction. This procedure will be described in detail below.

The satellite direction vector P at the LLN coordinate system (the satellite direction vector in a mobile-fixed coordinate system) antenna direction vector in a mobile-fixed coordinate system Q, azimuth (yaw angle) detected value phi _t, calculated want attitude The following relational expression holds for the roll angle ψ _S and the pitch angle θ _S , which are the values of.

Since the vector Q is a unit vector, the degree of freedom of the variable is 2. Thus equation (2) is for pending variable on the right side with respect to the left side of the two degrees of freedom is two [psi _S and theta _S, can be calculated [psi _S and theta _S.
From the satellite polarization direction vector R of the LLN coordinate system calculated from the position of the moving body, the satellite position, and the polarization angle information of the satellite, the oscillation values ψ _S and θ _S and the direction detection value φ _t obtained above, The satellite polarization direction vector T in the mobile fixed coordinate system can be calculated from the following equation.

Next, let us consider a case where an error δφ _t is included in this azimuth detection value. When the same calculation as in equation (2) is performed, the calculated roll angle and pitch angle do not become the roll angle true value ψ _t and the pitch angle true value θ _t , and errors δψ _S and δθ _S are It will be included. That is, this relationship can be expressed by the following equation.

On the other hand, the following equation holds for the roll angle true value ψ _t , the pitch angle true value θ _t , and the azimuth (yaw angle) true value φ _t .

  The following formula is obtained by comparing the formula (4) with the formula (5).

  In order to rearrange this equation (6), the satellite direction P in the LLN coordinate system is expressed using the angle α in the azimuth angle (Az) direction and the angle β in the elevation angle (El) direction as follows: .

When this is applied to Equation (6), also the generality simplified using this since it maintained as φ _{t +} α = 0 for simplicity, the following equation is obtained.

Next, when formula (8) is rearranged with a policy of ignoring the secondary minute amounts of δψ _S , δθ _S , and δφ _t , the following formula is obtained.

From this equation, for error .delta..phi _t, expression indicating the amount of error [Delta] [phi] _S and .delta..theta _S is obtained as follows.

From equation (11), .delta..phi _t is the error of the yaw angle (azimuth detection value), it can be seen that appears as the error [Delta] [phi] _S of -cosβ / sin (β-θ) multiplied by with the roll angle.

  Next, how there is a fluctuation estimation error in the roll angle and the yaw angle will be described. The relationship between the polarization angle direction, the roll angle, and the yaw angle error is as shown in FIG. As can be seen from FIG. 3, when the error in the polarization angle direction is δρ, δρ is the sum of the projections of the yaw angle error and the roll angle error. Therefore, the following equation is obtained.

  Summarizing equations (11) and (12) gives the following equation:

  From equation (13), it can be seen that the error δρ in the polarization angle direction is proportional to the yaw angle error δφ and diverges as the satellite elevation angle β decreases.

  On the other hand, when the detected values of fluctuation in the roll and pitch planes are used as known quantities, the following relationship is obtained by arranging them in the same manner.

  From equation (14), it can be seen that the error δρ in the polarization angle direction is proportional to the roll angle error δψ (actually the combination of the roll angle error and the pitch angle error) and diverges as the satellite elevation angle β increases. .

As described above, the error in the polarization angle direction increases as the satellite elevation angle decreases when the moving direction detection value is used as a known amount, whereas when the moving body fluctuation detection value is used. It can be seen that the satellite elevation angle increases as the satellite elevation angle increases. Therefore, if the satellite elevation angle is smaller than a predetermined value as a boundary, the motion detection value is used, whereas if the satellite elevation angle is larger than the predetermined value, the azimuth detection value is used to calculate the antenna attitude component, It becomes possible to suppress the control error of the polarization angle.
Since the errors included in the azimuth detection value and the shake detection value are determined by the performance of the equipment used for detection, the satellite elevation angle at which the polarization angle control error can be kept to a minimum as shown in FIG. The selection of both detection values may be switched by giving them as parameters.

  As described above, according to the first embodiment of the present invention, when the polarization angle generated by the attitude of the moving body is obtained, the movement is performed when the satellite elevation angle is a predetermined value or more in the calculation of the attitude component of the moving body. It is configured to use the body orientation detection value, and if the satellite elevation angle is less than the predetermined value, the motion detection value with respect to the horizontal plane of the moving body is used, so the polarization angle is calculated regardless of the satellite elevation angle. The error in can be suppressed to a small level, and the influence of the cross polarization component can be suppressed. In addition, it is possible to prevent a decrease in the degree of cross polarization identification of the antenna, and when using a satellite transponder, the influence on the back polarization can be suppressed to be small, and the satellite frequency can be effectively used. Become.

  In order to drive the antenna and change the directivity direction, it is necessary to provide a drive mechanism for each axis of the antenna, and a mechanical drive system such as 2-axis drive or 3-axis drive is used. In the case of biaxial driving, an AZ / EL mechanical driving method using an azimuth axis (AZ axis) and an elevation angle axis (EL axis) and an XY mechanical driving method using two horizontal axes are often used. In the case of 3-axis drive, a mechanical drive system that adds cross EL axis drive to the AZ / EL mechanical drive system, a mechanical drive system that adds EL axis drive to the AZ / cross EL drive, and XY drive to AZ drive A mechanical drive system or the like to add The biaxial drive has a simple mechanism because the number of axes is small, but the so-called zenith mode becomes a singular point of tracking. As a means for avoiding the zenith mode, the driving method by the three-axis driving provides an effective driving method. In the conical scan drive control method, the reception level is monitored by rotating the antenna directivity direction into a cone with a predetermined small cone apex angle, and the space search is performed while gradually shifting the antenna directivity direction. A technique such as driving control so that the wave level becomes larger is used. Further, in the step track drive control method, a technique is used in which a spatial search is performed by shifting the antenna directing direction stepwise, and drive control is performed so that the level of the received wave from the satellite becomes higher.

It is a block diagram which shows the function structure of the antenna attitude | position control apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the relationship between each axis | shaft in the fixed coordinate system of the moving body which mounts an antenna, and the attitude | position component of a moving body. It is explanatory drawing which shows the relationship between each axis | shaft in the LLN coordinate system of a mobile body position, and a polarization angle direction. It is explanatory drawing which shows the relationship between a polarization angle control error and a satellite elevation angle.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Antenna mirror surface, 2 Drive control part, 3 Tracking control part, 4 Position detection means, 5 Satellite direction calculation part, 6 Attitude calculation part, 7 Direction detection means, 8 Shake detection means, 9 Selection part, 10 Polarization angle calculation part , 11 Antenna axis drive control unit, 12 antenna polarization angle drive control unit.

Claims (2)

Position detecting means for detecting the position of the moving body, and a satellite direction calculation unit for calculating the satellite direction viewed from the position of the moving body based on the position detection value of the moving body and the satellite position information detected by the position detecting means. An azimuth detecting means for detecting the azimuth of the moving body, a sway detecting means for detecting the sway of the moving body with respect to the horizontal plane, and a azimuth detection value detected by the azimuth detecting means when the satellite elevation angle is a predetermined value or more. Calculating the attitude of the moving object, and when the satellite elevation angle is less than or equal to a predetermined value, the attitude calculating unit calculates the attitude of the moving object based on the motion detection value detected by the motion detecting means, and the attitude calculating unit A polarization angle calculation unit that calculates a polarization angle of a radio wave from the satellite based on the attitude of the mobile body calculated and the satellite direction calculated by the satellite direction calculation unit, and the polarization calculated by the polarization angle calculation unit Corner based There are antenna attitude control apparatus characterized by comprising a polarization angle adjusting means for adjusting the polarization angle of the antenna.   Position detecting means for detecting the position of the moving body, and a satellite direction calculation unit for calculating the satellite direction viewed from the position of the moving body based on the position detection value of the moving body and the satellite position information detected by the position detecting means. Calculated by the tracking control unit that controls the tracking of the antenna in the satellite direction, the direction detection unit that detects the direction of the moving object, the movement detection unit that detects the movement of the moving object with respect to the horizontal plane, and the satellite direction calculation unit. Satellite direction viewed from the position of the moving object, pointing direction of the antenna controlled by the tracking control unit in the moving object fixed reference coordinate system, and the direction detected by the direction detecting means when the satellite elevation angle is a predetermined value or more A posture calculation unit that calculates the posture of the moving body based on the motion detection value detected by the motion detection means when the detected value or the satellite elevation angle is equal to or smaller than a predetermined value; The polarization angle calculation unit that calculates the polarization angle of the radio wave from the satellite based on the attitude of the moving body calculated by the above and the satellite direction calculated by the satellite direction calculation unit, and the polarization angle calculation unit An antenna attitude control device comprising polarization angle adjusting means for adjusting the polarization angle of the antenna based on the polarization angle.

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