JP3120846B2 - Infrared tracking device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared tracking device, and more particularly, to an infrared tracking device having a high tracking performance of a target against a flare.

[0002]

2. Description of the Related Art Conventionally, an infrared tracking device has a basic configuration comprising a tracking control system including a dome 1, a gyro optical system 2, an amplification circuit 3, a detection circuit 4, a servo amplifier 5, and a torque generation section 6. . In this infrared tracking device, infrared light incident through the dome 1 enters the gyro optical system 2, is photoelectrically converted and amplified by the amplifier circuit 3, and the signal is detected by the detection circuit 4 in synchronization with the gyro rotation, and the detection output is output. Drives the torque generator 6 through the servo amplifier 5, thereby performing a control operation such that the gyro optical system 2 always tracks the target so as to be the maximum detection input.

When an aircraft or the like is tracked by such an infrared tracking device, the aircraft or the like sometimes drops a flare as a decoy to escape the tracking, and the energy emitted by the flare is smaller than the energy emitted by the aircraft itself. In this case, since it is large, the infrared tracking device tracks the flare, and there is a problem that it is impossible to track the target.

[0004] For such a flare drop, a method of tracking a direction closer to a target temperature based on an output ratio of a two-wavelength detector and a method of tracking a target from image processing of a two-dimensional image have been proposed. Further, an infrared tracking device configured to identify a flare and fix the swing angle of the gyro optical system to a state before dropping the flare to continue capturing a target is disclosed in, for example,
-268475 and JP-A-6-18642. The infrared tracking device described in the above publication uses a differential signal of an energy change rate of an effective value signal of an infrared detection output output from the gyro optical system as a flare detection method, or a differential signal of an angular velocity of the gyro optical system. ing.

[0005]

A conventional infrared tracking device requires a plurality of elements or image elements, and detects a flare by a differential signal of an infrared detection output or a differential signal of an angular velocity of a gyro optical system. Although it can be configured as a single element, it is erroneously determined that a flare is dropped due to fluctuations in the energy intensity emitted by the target itself and the avoidance behavior of the target trying to escape tracking, and the swing angle signal is sent to the torque generator. There was a problem that there was a risk of supply.
In addition, when a flare drop is detected, the gyro optical system's swing angle is fixed to the state immediately before flare detection.Therefore, after the flare drop, the swing angle gradually deviates from the optimal state with the elapsed time, and this expands. As a result, there is a problem that the flare may be out of the field of view and it may be difficult to re-capture the target.

(Object) It is an object of the present invention to provide an infrared tracking apparatus which can accurately detect a flare dropped from a target and has a high tracking performance.

Another object of the present invention is to provide an infrared tracking apparatus which can control the swing angle in a target predicting direction when detecting a flare dropped from a target and has high tracking performance.

[0008]

The infrared tracking device of the present invention has a control system (2, 3, 4, 5, and 6 in FIG. 1) for tracking infrared light from a target by a two-degree-of-freedom gimbal. In the reticle type gyro optical system,
A frequency determination circuit (7 in FIG. 1) for determining whether the target existing in the field of view is a single target or a plurality of targets based on the frequency characteristics of the output signal of the gyro optical system; A swing angle prediction circuit (11, 12, 1 in FIG. 1) that outputs a swing angle prediction signal for controlling the swing angle.
3, 14, 15, 19, and 20), the tracking operation is performed by the control system when the frequency determination circuit determines that the target is a single target in the target capture state. When the target is determined, the swing angle of the gyro optical system is controlled by the output of the swing angle prediction circuit.

The frequency determination circuit according to the present invention determines that a single target exists in the field of view of the gyro optical system when the frequency components of the input signal are distributed in a narrow predetermined frequency range, If the target is distributed in a frequency range wider than the predetermined frequency range, it is determined that a plurality of targets exist in the field of view of the gyro optical system. Furthermore, the swing angle prediction circuit includes a swing angle detector that outputs a swing angle signal of a gyro optical system, and the swing angle detector when the frequency determination circuit determines that the target is a single target. The swing angle storage unit that constantly updates and stores the output of the angular velocity detector that detects the angular velocity of the gyro optical system, and the angular velocity detector in a state where the frequency determination circuit determines that the target is a single target. An angular velocity storage unit that constantly updates and stores the output, and in a state where the frequency determination circuit has determined a plurality of targets, the frequency determination circuit determines a subtraction value between the output of the angular velocity storage unit and the aircraft angular velocity signal. A swing angle change calculating unit that multiplies an elapsed time after the plurality of targets have been determined, and adds the output of the swing angle storage unit and the output of the swing angle change calculating unit to calculate the swing angle. Output the prediction signal.

More specifically, a control system including a reticle-type gyro optical system, a detection circuit for detecting the output of the gyro optical system, and a torque generator for driving the gyro optical system based on the output of the detection circuit is provided. In the infrared tracking device, the frequency characteristic of the output signal of the gyro optical system is detected, and when the frequency of the signal is distributed in a predetermined frequency range according to the fundamental cycle of the reticle output, the gyro optical system is within the field of view. A frequency determination circuit that determines that one target is present, and determines that a plurality of targets are present in the field of view of the gyro optical system when the target is distributed in a wider frequency range than the predetermined frequency range; When the target is being tracked and the frequency determination circuit detects a signal in a frequency range wider than the predetermined frequency range, the control system is operated. , And drives the control signal of the predetermined neck gyro optics vibration angle in the case of a being tracked target and said frequency determination circuit has detected the signal of the predetermined frequency range.

(Operation) In an infrared tracking device having a two-degree-of-freedom gimbal of a reticle system (FM modulation system), infrared light incident through a dome is detected by a gyro optical system, and a frequency of a detection output is a single within a visual field. The frequency determination circuit determines whether the frequency range is when there is a target or when there are multiple objects including the target (a plurality of targets), and when it is determined that only the target is detected, the detection circuit performs gyro rotation. The gyro optical system is driven by the servo amplifier and torque generator based on the synchronously detected signal, and when tracking and when multiple targets are determined, the predicted swing angle signal (predicted swing angle signal) is commanded. The gyro optical system is driven by a servo amplifier and a torque generator as values.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Description of Configuration) Next, an embodiment of an infrared ray tracking device according to the present invention will be described.

FIG. 1 is a diagram showing a configuration example of the present embodiment. This embodiment has a control system of a feedback configuration including a dome 1, a gyro optical system 2, an amplification circuit 3, a detection circuit 4, a servo amplifier 5, and a torque generation unit 6, similarly to the conventional infrared tracking device.

The amplifying circuit 3 has a frequency judging circuit 7 on the output side, an AND circuit 8 operated by an output of the frequency judging circuit 7 and a target acquisition signal 9 inputted from outside, and an output of the AND circuit 8. A switch 10 for switching between operating the control system in a feedback configuration or disconnecting the feedback configuration and supplying a swing angle signal to the servo amplifier 5. And a switch 16 for switching and supplying a later-described swing angle prediction signal and an externally supplied slave command 17 as the swing angle signal. Further, in order to generate the swing angle prediction signal, the swing angle detector 1 is used.
1. Swing angle storage unit 12, angular velocity detector 13, angular velocity storage unit 14, swing angle change calculator 15, swing angle storage unit 12.
And a swing angle change calculator 15. The outline of the function or operation of each unit is as follows.

The gyro optical system 2 is a reticle type (FM)
Modulation method), the infrared light from the target incident through the dome 1 is condensed, and the reticle having a fan-shaped bright and dark stripe pattern is passed from the center of rotation provided at the center, thereby changing the pattern of the reticle. Do a light chopper. The output unit of the gyro optical system 2 performs infrared photoelectric conversion and outputs an electric signal having a chopping waveform to the amplifier circuit 3. The amplification circuit 3 amplifies the electric signal and outputs the electric signal to the detection circuit 4 and the frequency determination circuit 7.

The detection circuit 4 performs synchronous detection of the electric signal by a reference signal synchronized with the rotation of the gyro optical system 2 and supplies the electric signal to the servo amplifier 5 as an energy intensity. The servo amplifier 5 amplifies the detection output and drives the torque generator 6. The torque generator 6 outputs a torque for controlling the gyro optical system 2 to adjust the angle of the gyro optical system 2.

When the logic level of the target capture signal 9 indicates the target capture state, the switch 10 operates to connect the input and output of the detection circuit 4 and the servo amplifier 5.
In this case, the control system has a feedback configuration, and a feedback control operation is performed such that the energy intensity of the received infrared rays is maximized, and the gyro optical system 2 performs an operation of continuously and automatically tracking the target emitting the infrared rays. .

The frequency determination circuit 7 detects the frequency characteristic of the output of the detector amplified as an electric signal having a chopping waveform as described later, and determines whether the frequency characteristic is obtained when only one object exists in the visual field. It is determined whether the frequency characteristic corresponds to the presence of a plurality of objects, and a signal of a corresponding logic level is output.

The AND circuit 8 operates according to the logical output of the frequency judgment circuit 7 and the logical output of the target acquisition signal 9.
When the target acquisition signal 9 is at the logic level in the target acquisition state and at the logic level at which the frequency determination circuit 7 determines that only one object is detected, the switch 10 is switched to the contact a side to implement the control system. Feedback configuration. In this state, when the frequency determination circuit 7 changes the determination from one target to the detection of a plurality of targets, the AND circuit 8 switches the switch 10 to the contact b side, disconnects the feedback configuration, and swings the head. The angle signal is supplied to the servo amplifier 5.

The swing angle detector 11 detects and outputs the attitude angle of the gyro optical system. The angular velocity detector 13 detects and outputs the angular velocity based on the output of the gyro optical system. The swing angle storage unit 12 and the angular velocity storage unit 14 are both controlled by the output of the frequency determination circuit 7, and while the frequency determination circuit 7 detects only one target, the swing angle detector 11 and The output signal of the angular velocity detector 13 is sampled as needed, and the value is updated and stored. Therefore, when the frequency determination circuit 7 determines the detection of a plurality of targets, the swing angle detector 11 and the angular velocity detector 13 continue to output the stored values immediately before the determination.

The subtractor 19 outputs the angular velocity signal of the gyro optical system 2 and the body angular velocity signal 1 based on the output of the angular velocity detector 13.
8 is output. The swing angle change calculator 15 is controlled by the output of the frequency determination circuit 7 and multiplies the subtraction value of the subtractor 19 by the elapsed time from the time when the frequency determination circuit 7 detects a plurality of targets to calculate the elapsed time. And outputs a signal corresponding to the change in the swing angle. The adder 20 includes a swing angle change calculator 15 and a swing angle storage 1
2 is added to output the swing angle prediction signal.

The switch 16 is controlled by the target acquisition signal 9 and receives either the swing angle prediction signal or a slave command 17 of the swing angle signal obtained from another external sensor such as a radar. Supply to the side. In other words, if the target tracking fails and the logic level of the target capture signal 9 indicates the target non-capture state, the AND circuit 8 switches the switch 1
The switch 0 is switched to the contact b side, and the switch 16 is further switched to the contact d side, and the signal of the slave command 17 is supplied to the servo amplifier 5 as the swing angle signal.

(Explanation of Operation) First, the operation of the frequency determination circuit used in the present embodiment will be described in detail.
The present embodiment employs a reticle-type two-degree-of-freedom gimbal. In a tracking state for a target infrared ray entering the field of view of the gyro optical system 2, the error angle of the gyro optical system 2, the number of targets, and the like are determined. The fact that the mode of the chopping waveform of the signal output from the gyro optical system differs depending on the mode is utilized.

FIGS. 2 to 4 are diagrams showing the relationship between the error angle of the gyro optical system 2, the trajectory of the target infrared ray drawn on the reticle, and the chopping waveform of the output of the gyro optical system 2 after limiting the amplitude.

When the gyro optical system 2 enters a tracking state with a target in its field of view, the frequency of the output of the amplifier circuit 3 depends on the error between the direction of the gyro optical system 2 and the target direction and the target number. The components have different characteristics such as falling within a predetermined frequency range.

For example, when the error angle is 0 °, the focal point of the infrared ray on the rotating reticle draws a locus of a dotted line as shown in FIG. 2, and the output waveform by the chopping operation has a duty ratio as shown in the right figure. Is approximately 50%, the signal in the frequency range of the repetition frequency of the chopping waveform is large, and the signal is in a narrow frequency range close to a single frequency. Also, when there is an error angle, the condensing point draws a locus of a dotted line as shown in FIG. 3, and the output waveform has a duty ratio from 50% as shown in the right figure in a range where it moves only to the end of the visual field. It becomes a signal that changes, and contains harmonic frequencies but falls within a fixed frequency range. When there are a plurality of targets, a locus of a dotted line as shown in FIG. 4 is drawn, and the frequency range is further expanded. Further, when the tracking point becomes indefinite, more high-frequency components are introduced.

Accordingly, each state can be determined by detecting the frequency range of the chopping waveform output in relation to the target tracking state, the tracking indefinite state, and the target number. The frequency determination circuit 7 of the present embodiment determines whether or not the number of targets being captured is one based on the properties of the output signal of the gyro optical system 2. In particular,
The frequency determination circuit 7 according to the present embodiment determines whether the target is single, multiple, or in an uncertain tracking state by centering on the repetition frequency of the chopping waveform determined by the reticle stripe pattern and the rotation speed. An example will be described below in which the determination is made based on the width of the image.

Next, the tracking operation of the infrared tracking device of the present embodiment will be described in detail below, assuming that a target drops a flare during tracking of a single target.

In the target tracking state, the infrared light incident through the dome 1 enters the gyro optical system 2 and is focused on a reticle having a bright and dark stripe pattern. The signal is amplified by the amplifier circuit 3 and output. Since the target is in the target capturing state, the target capturing signal 9 outputs a logical level indicating the target capturing, and the switch 16 is connected to the contact c to which the swing angle prediction signal is applied. Then, the frequency detection circuit 7 detects that the frequency is within the frequency range of the basic cycle corresponding to the cycle of the reticle stripe pattern, and outputs a single target determination result. 10 are connected on the contact a side. Therefore, in this state, the signal of the chopping waveform is synchronously detected by the reference signal synchronized with the gyro rotation in the detection circuit 4, and the detection output is transmitted to the torque generator 6 via the servo amplifier 5.
And the gyro optical system 2 is driven such that the level of infrared rays is maximized, and control for automatically tracking the target is performed.

Next, when the target drops a flare, the gyro optical system detects the target and the flare, that is, two target infrared rays in the field of view, and the frequency judgment circuit 7 detects a signal in a wider frequency range. Then, it is determined that there are a plurality of targets, and the logical level of the output is switched. The AND circuit 8 switches the switch 10 to the contact b side because the logical product is not established due to the inversion of the output of the frequency determination circuit 7.

A time-varying wobble angle prediction signal predicted from the wobble angle and angular velocity during tracking of a single target is applied to the contact b of the switch 10 by the operation described below. The swing angle prediction signal controls the torque generator 6 via the servo amplifier 5 to drive the gyro optical system 2 in the prediction direction. As the swing angle prediction signal supplied to the contact b of the switch 10, various swing angle calculation methods can be used.

Next, the operation of calculating the swing angle prediction signal according to the present embodiment will be described in detail. First, in the target tracking state, the swing angle storage unit 12 samples and holds the attitude angle of the gyro optical system 2 detected by the swing angle detector 11 at any time, and the frequency determination circuit 7 detects a single target. The memory of the latest posture angle value is updated as long as possible. The angular velocity storage unit 14 samples and holds the angular velocity of the gyro optical system 2 detected by the angular velocity detector 13 as needed, and stores the latest attitude angle value as long as the frequency determination circuit 7 detects a single target. Has been updated.

When the frequency determination circuit 7 determines that a plurality of targets have been detected, the swing angle storage unit 12 and the angular velocity storage unit 1
4 stops updating the storage and continues to output the storage values immediately before the detection of a plurality of targets, respectively. Here, since the angular velocity obtained from the angular velocity storage section 14 is a spatial angular velocity, a difference value between the angular velocity signal 18 and the body angular velocity signal 18 is calculated by the subtracter 19 and output to the head-swing angle change calculating section 15. Fifteen
Multiplies the difference value of the angular velocities by the elapsed time from the point in time when the frequency determination circuit 7 determines that a plurality of targets exist, and calculates and outputs a temporal change in the swing angle. The adder 20 calculates a predicted swing angle signal by adding the output of the swing angle change calculating unit 15 and the output of the swing angle storage unit 12, and sends the signal to the contact b of the switch 10 via the contact c of the switch 16. Supplied.

Further, in any of the above operating states,
When the target capture signal 9 no longer indicates the target capture state, the switch 16 is connected at the contact d and the slave command 1
7 is applied to the servo amplifier 5. Slave command 17
Is a target angle signal detected by another sensor such as a radar, and is given from outside the apparatus. Slave command 1
When the target is captured by 7, the target capture signal 9 indicates the target capture state, and the operation returns to any of the above-described operations.

As described above, according to the present embodiment, when the frequency determination circuit 7 determines that the target is a single target and the target capture signal 9 indicates the capture state, the AND circuit 8 switches based on these two conditions. 10 is connected to the detection circuit 4 side, and the infrared tracking device performs a normal target tracking operation. In other conditions, the AND circuit 8 connects the switch circuit 10 to the predicted swing angle signal side, and when the target capture signal 9 indicates the capture state, the servo amplifier 5 predicts the swing angle prediction. When the target acquisition signal 9 does not indicate the acquisition state, the apparatus is supplied with a swing angle signal of an external command signal to perform reacquisition. Further, when a plurality of targets are detected during tracking of the target, the swing angle prediction signal includes a swing angle according to the elapsed time based on the angular velocity at the same time as the swing angle at that time. Then, a predicted swing angle is calculated by adding the change angle of.

In the present embodiment described above, an example has been described in which the frequency determination circuit determines the target number or the like based on the frequency component of the signal of the chopping waveform, but the frequency of the signal of the chopping waveform obtained from the gyro optical system is described. Obviously, the determination can be made by analyzing the output waveform instead of the analysis. Further, it is needless to say that only the output of the swing angle storage unit can be used as the swing angle prediction signal, and a change after the detection of a plurality of targets is not added.

[0037]

According to the present invention, the original target and the flare drop are determined by analyzing the frequency components of the output of the gyro optical system of the reticle system. It is less affected and can prevent erroneous determination of flare dropping, and can achieve a high target tracking characteristic.

While the flare is in the field of view of the gyro optical system, the direction in which the target moves is predicted to change the gyro optical system's swing angle over time. It is possible to easily and quickly shift to the tracking state even when deviating from the visual field. For this reason, it is possible to improve the tracking performance against fraud by fraud.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of an infrared tracking device of the present invention.

FIG. 2 is a diagram showing a trajectory of a focus point of infrared rays on a rotating reticle when an error angle of a gyro optical system with respect to a target is 0 °.

FIG. 3 is a diagram showing a trajectory of a focal point of an infrared ray on a rotating reticle when there is an error angle with respect to a target of the gyro optical system.

FIG. 4 is a diagram illustrating a trajectory of a focal point of infrared rays on a rotating reticle when there are a plurality of targets.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dome 2 Gyro optical system 3 Amplification circuit 4 Detection circuit 5 Servo amplifier 6 Torque generator 7 Frequency judgment circuit 8 AND circuit 9 Target capture signal 10 Switch 11 Shaking angle detector 12 Shaking angle storage unit 13 Angular velocity detector 14 Angular velocity Storage unit 15 Swing angle change calculation unit 16 Switch 17 Slave command 18 Aircraft angular velocity signal 19 Subtractor 20 Adder

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01S 3/78-3/789 F41G ⁷ /00-7/36

Claims (6)

(57) [Claims] An infrared tracking device having a control system for tracking infrared rays from a target by a two-degree-of-freedom gimbal, wherein a target existing in a visual field by a reticle type gyro optical system and a frequency characteristic of an output signal of the gyro optical system. A frequency determination circuit that determines whether the target is a single target or a plurality of targets, a swing angle prediction circuit that outputs a swing angle prediction signal that controls the swing angle of the gyro optical system in the target capture state, and a target capture state The tracking operation by the control system is performed when the frequency determination circuit determines that the target is a single target, and the output of the swing angle prediction circuit when the frequency determination circuit determines a plurality of targets in the target capture state. An infrared tracking device characterized by controlling a swing angle of a gyro optical system. 2. The frequency judgment circuit judges that a single target exists in the field of view of the gyro optical system when the frequency components of the input signal are distributed in a narrow predetermined frequency range. 2. The infrared tracking apparatus according to claim 1, wherein if the frequency distribution is wider than the range, it is determined that there are a plurality of targets in the field of view of the gyro optical system. 3. The swing angle prediction circuit according to claim 1, wherein the swing angle detector outputs a swing angle signal of a gyro optical system, and the swing determination circuit determines that the swing determination is performed as a single target. A swing angle storage unit that constantly updates and stores the output of the angle detector, and the swing angle storage unit outputs the swing angle prediction signal in a state where the frequency determination circuit determines a plurality of targets. 3. The method according to claim 1, wherein
An infrared tracking device as described. 4. The swing angle prediction circuit according to claim 1, wherein the swing angle detector outputs a swing angle signal of a gyro optical system, and the swing determination circuit determines that the swing determination is performed as a single target. A swing angle storage unit that constantly updates and stores the output of the angle detector, an angular velocity detector that detects the angular velocity of the gyro optical system, and the angular velocity in a state where the frequency determination circuit determines that the target is a single target. An angular velocity storage unit that constantly updates and stores the output of the detector; and, in a state where the frequency determination circuit determines that a plurality of targets have been obtained, subtracts the output of the angular velocity storage unit from the airframe angular velocity signal to obtain the frequency. The determination circuit has a swing angle change calculation unit that multiplies the elapsed time after determining the plurality of targets, and adds the output of the swing angle storage unit and the output of the swing angle change calculation unit. Output the swing angle prediction signal 3. The infrared tracking device according to claim 1, wherein 5. The gyro optical system according to claim 1, wherein, in a non-capturing state of the target, the gyro optical system is controlled by a command value from an external sensor or the like instead of the oscillating angle prediction signal. 5. The infrared tracking device according to 2, 3, or 4. 6. An infrared tracking apparatus having a control system including a reticle type gyro optical system, a detection circuit for detecting an output of the gyro optical system, and a torque generator for driving the gyro optical system based on an output of the detection circuit. In the detecting the frequency characteristics of the output signal of the gyro optical system,
If the frequency of the signal is distributed in a predetermined frequency range corresponding to the fundamental cycle of the reticle output, it is determined that one target exists in the field of view of the gyro optical system, and a frequency wider than the predetermined frequency range is determined. A frequency determination circuit that determines that a plurality of targets are present in the field of view of the gyro optical system when distributed in a range; a frequency range in which the target is being tracked and the frequency determination circuit is wider than the predetermined frequency range. When the signal is detected, the control system is operated, and when the target is being tracked and the frequency determination circuit is detecting a signal in the predetermined frequency range, the gyro optical system is set to a predetermined frequency. An infrared tracking device driven by a control signal of a swing angle.