JPH05164830A - Automatic tracking system - Google Patents

Abstract

PURPOSE:To obtain an automatic tracking system for a video camera which can readily prevent troubles caused by radio interference. CONSTITUTION:A radio wave generated from an oscillator 2 kept by a subject is detected by a first and a second radio wave receivers 7, 8. Output from the radio wave receivers 7, 8 is mixed with output from a local oscillator 15 by a first and a second mixer 13, 14 to obtain a first and a second differential frequency signal. The first and the second differential frequency signal are passed through low-pass filters 16, 17 and are then inputted to a phase comparator 8. The output of the phase comparator 18 controls a motor 5a to have a camera tracked the subject. A frequency component based on radio interference is inhibited by the low-pass filters 16, 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a public automatic tracking device for automatically tracking a video camera on an object.

[0002]

2. Description of the Related Art In order to automatically track a video camera to a subject, an oscillator or a light source is attached to the subject, and the radio waves emitted from the subject are detected by a plurality of wave receivers. There has been proposed an automatic tracking device configured to detect the movement of an object based on the phase difference of frequency signals and move the video camera so that the phase difference becomes zero.

[0003]

However, when a plurality of automatic tracking video cameras of the same type are used in close proximity, the frequency difference between them is usually about 20 kHz. May receive and malfunction.

Therefore, an object of the present invention is to provide an automatic tracking device in which malfunction due to interference is unlikely to occur.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a tracking object for automatically tracking a moving object with a wave signal generator, and a support for supporting the tracking object. And a drive means for moving the tracking object relative to the support, and a control means for controlling the drive means, wherein the control means generates a wave signal generated from the wave signal generator. First and second wave receivers respectively attached to the tracking object at a predetermined interval to receive a signal, a local oscillator for generating a signal having a frequency close to the frequency of the wave signal, and the first and second wave receivers. A first mixer for mixing a first output signal obtained from the first receiver and a local oscillation frequency signal obtained from the local oscillator to form a frequency signal having a first difference; Second output from the two receivers Signal mixing means for mixing the local oscillation frequency signal and the local oscillation frequency signal to form a second difference frequency signal, and the first and second mixers respectively connected to the first and second mixers. A first and a second low pass filter for passing the difference frequency signal, and a signal corresponding to the phase difference between the first and the second difference frequency signal passed through the first and second low pass filters. The present invention relates to an automatic tracking device that includes a phase comparator that controls the driving means so as to reduce the phase difference.

[0006]

If the frequency of the local oscillator according to the present invention has a difference of 100 Hz from the frequencies of the first and second output frequency signals, the first and second mixers are provided. From 100 as the frequency signal of the first and second differences
A Hz signal is obtained. This 100Hz frequency is the first
And the second low-pass filter to become the input of the phase comparator, and the phases are compared. If the distances between the first and second wave receivers and the wave signal generator of the moving object are not equal, a phase difference occurs between the two inputs of the phase comparator. Therefore, when the tracking object is driven so that this phase difference becomes zero, automatic tracking is achieved. Two automatic tracking devices of the same type are used close to each other, and the frequency of both wave signal generators is, for example, 20.
If there is a difference of kHz, even if the wave signal of one automatic tracking device is input to the receiver of the other automatic tracking device, the output frequencies of the first and second mixers are, for example, 20.
It becomes 1kHz, for example, the first and second which pass 100Hz
Can be completely blocked by the low pass filter of Therefore, it is possible to obtain a phase comparison output that is not affected by the frequency signal of another automatic tracking apparatus that is in close proximity, and it is possible to perform accurate automatic tracking.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an automatic tracking device for a video camera according to an embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 2, an automatic tracking device of a video camera has a transmitting antenna as a wave signal generator attached to an object 1 such as a person who is a moving object, for example, 1,0.
An oscillator 2 of 0,000 kHz, a video camera 3 as a tracking object, a support 4 of the camera 3, and a camera 3
A drive device 5 for moving the relative to the support body 4,
The control device 6 controls the drive device 5 so that the camera 3 tracks the subject 1. The control device 6 receives radio waves continuously radiated from the oscillator 2 of the subject 1 and
The angular position of the camera 3 with respect to is determined, and the drive device 5 is controlled so that the camera 3 tracks the subject 1. The drive device 5 is composed of a motor 5a supported by a support 4 and a rotation shaft 5b provided between the motor 5a and the camera 3, and the rotation of the motor 5a rotates the camera 3 in one plane. Let

FIG. 1 shows the control device 6 of FIG. 2 in detail. The control device 6 has first and second wave receivers (antennas) 7 and 8 which are fixedly arranged on the camera 3 at a constant distance D in the rotation plane of the camera 3. The first and second wave receivers 7 and 8 receive the radio wave radiated from the oscillator 2 of the subject at the first frequency f1 (for example, 1,000,000 kHz), and output the first and second output signals of the frequency f1. Is sent.

First and second bandpass filters 9 and 10 connected to the first and second wave receivers 7 and 8 extract a component of the first frequency f1 of the first and second output signals. Is configured to. Since it is practically impossible or difficult to configure the first and second bandpass filters 9 and 10 to extract only the specific frequency f1, for example,
Another frequency signal having a difference of about 20 kHz from f1 also passes through the bandpass filters 9 and 10. The first and second bandpass filters 9 and 10 are the first and second amplifiers 1
It is connected to the first and second mixers 13 and 14 through 1 and 12.

The local oscillator 15 outputs a signal of a second frequency f2 close to the first frequency f1 (for example, a frequency 100 Hz lower than f1). Since the local oscillator 15 is connected to the first and second mixers 13 and 14, the first and second mixers 13 and 14 have the first and second frequencies f.
1 and f2 are mixed, and the output of the difference between them, f1 -f2 = f3, is obtained. The third frequency f3, which is the difference between the two frequencies f1 and f2, is 100 Hz, which is an extremely low value.

The output signals of the first and second mixers 13 and 14 pass through the first and second low pass filters 16 and 17 and become the input of the phase comparator 18. The first and second low-pass filters 16 and 17 are configured to pass signals of the third frequency f3, but block signals of a frequency significantly higher than this. That is, the signal of the frequency difference (for example, 20 kHz) of the subject oscillator 2 for distinguishing a plurality of automatic tracking devices of the same type is configured to be blocked. Therefore, the radio waves from the oscillator of the adjacent automatic tracking camera system are input to the wave receivers 7 and 8, and based on this, the first and second mixers 13 and 14 output a difference frequency of, for example, about 20.1 kHz. Even if occurs, it is blocked by the low-pass filters 16 and 17.

The phase comparator 18 is, for example, as shown in FIGS.
The phase comparison output of the two frequency signals shown in FIG. If the distances L1 and L2 from the first and second wave receivers 7 and 8 to the subject oscillator 2 are the same, the two inputs of the phase comparator 18 have the same phase, but the subject oscillator 2 moves. Then, when a difference occurs between the distances L1 and L2, a phase difference Q is generated as shown in FIGS. The output of the phase comparator 18 is supplied to the motor 5a via the low-pass filter 19, and the motor 5a rotates the camera 3 and the wave receivers 7 and 8 so as to reduce the phase difference. As a result, the camera 3 automatically tracks the movement of the subject 1.

[0014]

MODIFICATION The present invention is not limited to the above-described embodiments, and the following modifications are possible, for example. (1) The camera 3 is supported by a gimbal, and a tracking control circuit as shown in FIG. 1 is provided on a plane orthogonal to the horizontal plane.
The camera 3 can be configured to move in various directions. (2) It is also possible to arrange more wave receivers on the same plane and control the direction of the camera 3 based on a plurality of outputs. (3) Instead of generating an electric wave from the oscillator 2, a light wave,
Ultrasonic waves can be generated.

[Brief description of drawings]

FIG. 1 is a diagram showing an automatic tracking control circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an automatic tracking device of the video camera of the embodiment.

FIG. 3 is a waveform diagram showing an input of the phase comparator of FIG.

[Explanation of symbols]

 2 Object oscillator 7,8 Receiver 13,14 Mixer 15 Local oscillator 16,17 Low-pass filter 18 Phase comparator

Claims (1)

[Claims] 1. A tracking object for automatically tracking a moving object with a wave signal generator, a support for supporting the tracking object, and a movement of the tracking object relative to the support. A driving means and a control means for controlling the driving means are provided, wherein the control means has a predetermined interval for receiving the wave signal generated from the wave signal generator to the tracking object. First and second wave receivers respectively attached, a local oscillator that generates a signal of a frequency close to the frequency of the wave signal, and a first output signal obtained from the first wave receiver A first mixer for mixing with a local oscillation frequency signal obtained from the local oscillator to form a frequency signal having a first difference; and a second output signal obtained from the second receiver. The local oscillation frequency signal is mixed with the second Second mixer for forming a frequency signal of the first and second low-pass filters for passing the frequency signals of the first and second differences respectively connected to the first and second mixers. A filter and a signal corresponding to a phase difference between the frequency signals having the first and second differences that have passed through the first and second low-pass filters, and controlling the driving unit to reduce the phase difference. An automatic tracking device, comprising: