The present application claims priority from Japanese Patent application serial no. 2018-063549 filed on Mar. 29, 2018, the content of which is hereby incorporated by reference into this application.
The present invention relates to a moving object imaging system and a moving object imaging method suitable for tracking and imaging of a flying object freely moving in space.
In the related art, there are known apparatuses that capture images of moving objects such flying objects moving in a target region. In order to track a moving object in motion and capture an image thereof, it is necessary to control the optical axis of the camera so as to capture the moving object in the imaging range of the camera. As a control method for directing the optical axis of the camera to the moving object, there is a known method capable of directing the optical axis of the camera to the moving object by driving a plurality of rotatable movable mirrors with motors having different rotation axes.
This technique is disclosed in, for example, JP-A-H10-136234. In the abstract of the document, the following description is given.
“A light transmissive window W1 is provided in a non-light-transmissive housing B1. In addition, in the non-light-transmissive housing B1, an imaging apparatus C1, an azimuth angle rotatable reflecting mirror M1, a tilt angle rotatable reflecting mirror M2, and motors m1 and m2 rotating the mirrors M1 and M2 are disposed. The rays I from the field of view of a subject pass through the window W1, and are then regularly reflected by the mirror M1, and reflected again by the mirror M2. Thereby, an image of the subject returns to an erect image, and the erect image of the subject is incident into the imaging apparatus C1.”
There is also known a technique of detecting change in posture of a camera due to disturbance or the like with an acceleration sensor and correcting the inclination of the captured image. For example, in the abstract of JP-A-2017-225039, the following description is given. “An imaging apparatus includes: an optical system; an element that outputs an image, which is incident through the optical system, as image data; an acceleration sensor that outputs a signal representing acceleration in three axial directions; an angular velocity sensor that outputs a signal representing an angular velocity around the three axes; and a circuit that processes the image data. The circuit corrects a low frequency component of the inclination of the image on the basis of the acceleration, and performs correction processing of correcting a high frequency component of the inclination of the image on the basis of the angular velocity.”
The method of installing the surveillance camera is not explicitly described in JP-A-H10-136234, in order to install the camera at a desired place. However, considering the ease of installation and movement and the degree of freedom, the camera is not strongly fixed to the ground or a structural member, but mostly fixed by using a simple supporting apparatus such as a tripod. In a case of adopting such a simple installation mode, there is a possibility that the posture of the surveillance camera changes due to disturbance such as wind or vehicle vibration in the outdoors. In addition, even in the indoor, the posture of the surveillance camera may change due to disturbance such as floor vibration caused by walking of a person. Then, especially when high-ratio zoom imaging is performed, blurring synchronized with disturbance may be mixed in the captured image data.
In JP-A-2017-225039, in a case where the posture of the camera changes due to disturbance, the inclination of the image data is corrected through image processing on the basis of acceleration, such that blurring is suppressed. However, since the inclination is corrected through image processing, it is difficult to cope with the change in posture of the movable mirror due to the influence of the disturbance which occurs in the camera having the movable mirror as in JP-A-H10-136234.
The present invention has been made in consideration of the above, and it is an object of the present invention to provide a moving object imaging system and a moving object imaging method capable of preventing blurring from being mixed in captured image data by controlling the posture of the movable mirror in accordance with disturbance even in a case where a camera using a movable mirror (reflecting mirror) is not fixed to the ground or a structural member and is installed on a simple supporting apparatus such as a tripod without a vibration damping apparatus.
In order to achieve the above-mentioned object, in the present invention, a moving object imaging system of the present invention includes: an imager that captures an image of a moving object and outputs captured image data; a deflector that changes a deflection angle of an optical axis of the imager by rotating a reflecting mirror; a housing that supports the deflector; a posture change detector that detects change in posture of the housing; and a control unit that controls a deflection angle of the deflector in accordance with a detection result of the posture change detector.
According to the present invention, even in the case where the camera using the movable mirror (reflecting mirror) is not fixed to the ground surface or the structural member and the camera is installed on a simple supporting apparatus such as a tripod without the vibration damping apparatus, it is possible to prevent the blurring from being mixed in the captured image data by controlling the posture of the movable mirror in accordance with disturbance.
Hereinafter, examples of the present invention will be described. In the following examples, for the sake of convenience, description will be given with reference to a plurality of examples. Unless otherwise stated, the examples do not unrelate to one another such that one example is a part of another example, or a modification example, details, supplementary explanation, or the like of all examples.
A moving object imaging system according to Example 1 of the present invention will be described with reference to
In the moving object imaging apparatus 1 shown here, the imager 7 and the deflection unit 3 are provided on the base of a rigid body such that the optical axis of the imager 7 is parallel to the x axis and the optical axis of the imager 7 can be deflected in the vertical direction or the lateral direction by the deflection unit 3. The moving object imaging apparatus 1 also includes an imaging apparatus control unit 2 that controls the imaging timing and the imaging magnification of the imager 7, the deflection angle in the deflection unit 3, and the like. Thus, the captured image data 8, which is obtained by tracking the flying object 10 through the control, is output from the imager 7.
In order to track the optical axis of the imager 7 on the flying object 10, the deflection unit 3 includes a reflecting mirror 4x that deflects the optical axis in the vertical direction, and a reflecting mirror 4y that deflects the optical axis in the lateral direction, in a housing 3a made of a rigid body such as a steel plate. In addition, the deflection unit 3 includes a deflector 5x that rotates the reflecting mirror 4x around the x axis, on the side surface of the housing 3a, and a deflector 5y that rotates the reflecting mirror 4y around the y axis, on the upper surface of the housing 3a. It should be noted that the reflecting mirrors 4x and 4y and the deflectors 5x and 5y may be collectively referred to as a deflection unit. Further, an angular velocity sensor 6x is disposed on the rotation axis of the deflector 5x, and an angular velocity sensor 6y is disposed on the rotation axis of the deflector 5y. By using the angular velocity sensors 6x and 6y, in a case where the posture of the deflection unit 3 changes due to the influence of disturbance such as vibration or wind, the amount of rotation Δθx around the x axis can be detected on the basis of the angular velocity ωx which is output from the angular velocity sensor 6x, and the amount of rotation Δθy around the y axis can be detected on the basis of the angular velocity ωy which is output from the angular velocity sensor 6y. In the following description, the two reflecting mirrors may be collectively referred to as the reflecting mirror 4, the two deflectors may be collectively referred to as a deflector 5, and the two angular velocity sensors may be collectively referred to as an angular velocity sensor 6.
In addition to a motor (not shown) such as a galvano motor capable of angle control, the deflector 5 includes an angle sensor 51 such as an encoder that detects the deflection angle of the motor shown in
The imaging apparatus control unit 2 further includes a target angle calculation unit 2a that calculates a target deflection angle θ0 of the reflecting mirror 4 necessary for tracking the flying object 10 and capturing an image of the flying object 10 at the center of the captured image data 8, a deflection angle command unit 2b that outputs a deflection angle command value θ1 based on a target deflection angle θ0 to the motor control unit 52 of the deflector 5, an angular velocity detection unit 2c that detects the angular velocity ω from the output of the angular velocity sensor 6, and an imager control unit (not shown) that controls the imaging timing of the imager 7. The functions of the respective units in the imaging apparatus control unit 2 are realized by loading a program stored in an auxiliary storage device such as a hard disk or the like of the imaging apparatus control unit 2 on a main storage device such as a semiconductor memory and the like and causing a computing device such as a CPU to execute the program. However, in the following description, such well-known operations will be appropriately omitted, and description thereof will be given.
In the deflector 5, a value obtained by subtracting a motor rotation angle θ2 detected by the angle sensor 51 from the received deflection angle command value θ1 is input to a compensator C. Then, a current value corresponding to the difference between the deflection angle command value θ1 and the motor rotation angle θ2 is output from the compensator C, and the motor rotates in accordance with the current value. As a result, the reflecting mirror 4 is set at a predetermined angle designated by the imaging apparatus control unit 2.
As described above, in the present example, the deflector 5 is controlled by using the deflection angle command value θ1 that cancels the amount of rotation Δθ due to disturbance such as wind. With such a configuration, even in a case where the posture of the deflection unit 3 changes due to the influence of disturbance, the deflection angle of the reflecting mirror 4 is sequentially corrected in a direction to cancel out the influence of the disturbance. As a result, the influence of disturbance can be suppressed in the captured image data 8 of the imager 7, and the captured image data 8 can be made free from blurring.
As described above, according to the present example, even in a case where the moving object imaging apparatus using the deflection unit is installed on the simple supporting apparatus such as a tripod, it is possible to prevent blurring from being mixed in the captured image data by controlling the posture of the reflecting mirror in the deflection unit in accordance with disturbance such as wind.
Next, a moving object imaging system according to Example 2 of the present invention will be described with reference to
In the moving object imaging system of Example 1, change in posture around the rotation axis of the reflecting mirror 4 is detected as the amount of rotation Δθ by using the angular velocity sensor 6. However, in the configuration of the moving object imaging system of the present example, by using an acceleration sensor 9 to be described later, the change in posture due to the movement of the housing 3a of the deflection unit 3 is detected as an amount of shift Δ, and display data 8a to be displayed on the image display device 30 is extracted on the basis of the amount of shift Δ.
The acceleration sensor 9 of the present example is capable of individually detecting accelerations a (ax, ay, az) in three directions applied in a case where the deflection unit 3 moves due to disturbance such as wind. Then, the correction amount calculation unit 2e of the imaging apparatus control unit 2 performs the integration processing twice on the acceleration a in each direction, thereby calculating the amount of movement of the deflection unit 3 due to disturbance (amount of shift Δ (Δx, Δy, Δz)).
Next, a processing method of the captured image data 8 using the amount of shift Δ will be described with reference to
As described above, the amount of shift Δ, which is output by the correction amount calculation unit 2e, corresponds to the amount of movement of the deflection unit 3 due to disturbance. Thus, in a case where the amount of shift Δ is output, it can be presumed that the flying object 10 on the captured image data 8 is at a position which is shifted by the amount of shift Δ from a position predetermined by the imaging apparatus control unit 2.
In order to correct this shift, the image processing device 20 of the present example extracts a region with a predetermined size shifted by an amount of shift, which is input from the correction amount calculation unit 2e, Δ from the center of the captured image data 8 on the basis of the amount of shift Δ, and transmits the region as display data 8a to the image display device 30. Through this processing, the display data 8a corrected for the influence of the amount of shift Δ due to the disturbance can be displayed on the image display device 30. Thus, even in a case where the display data 8a is a moving image, the influence of blurring due to disturbance can be reduced.
According to the moving object imaging apparatus of the present example described above, it is possible to suppress the disturbance influence through the control shown in
Next, a moving object imaging system according to Example 3 of the present invention will be described with reference to
In Examples 1 and 2, the deflection angle of the reflecting mirror 4 is corrected on the basis of the amount of rotation Δθ around the axis of the deflection unit 3 detected by the angular velocity sensor 6, and in Example 2, the deflection detected by the acceleration sensor 9 On the basis of the amount of shift Δ of the deflection unit 3, the display data 8a was extracted from the captured image data 8.
On the other hand, in the moving object imaging system of the present example, two acceleration sensors 9 are provided on the surface of the housing 3a of the deflection unit 3. On the basis of these outputs, the amount of rotation Δθ around the axis of the deflection unit 3 and the amount of shift Δ are calculated. Thereby, even in a configuration in which the angular velocity sensor 6 is omitted, control for coping with disturbance according to Examples 1 and 2 can be executed.
Next, a method of calculating the amount of shift Δ and the amount of rotation Δθ of the deflection unit 3 through the correction amount calculation unit of the imaging apparatus control unit 2 will be described with reference to
The amount of rotation Δθ obtained by the correction amount calculation unit 2e on the basis of Equation 1 is equivalent to the amount of rotation Δθ of the deflection unit 3 in
In addition to the image processing in consideration of the amount of shift Δ as in Example 2, the present example also executes image processing in which the amount of rotation Δθ of the deflection unit 3 is considered. As shown in
In the image processing device 20 of the present example, in a manner similar to that of Example 2, the image processing in which the amount of shift Δ is considered is performed, and then the display data 8a is determined. In the present example, unlike Example 2, since the outputs of the two acceleration sensors 9 are obtained, the correction amount calculation unit 2e calculates the amount of shift Δ used for the image correction processing on the basis of the following (Expression 2).
According to the moving object imaging apparatus 1 of the present example described above, in addition to the effects obtained in Examples 1 and 2, the influence of the inclination of the deflection unit 3 due to disturbance can be removed from the display data 8a displayed on the image display device 30. Therefore, the display data 8a with higher quality can be displayed.
It should be noted that the present invention is not limited to the above-mentioned examples, but includes various modification examples. For example, the above-mentioned examples have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one example may be replaced by the configuration of another example, and the configuration of one example may be added to the configuration of another example. Further, in the configuration of each example, addition of another configuration, deletion, and replacement may be possible.
Number | Date | Country | Kind |
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2018-063549 | Mar 2018 | JP | national |