JPS62119475A - Tracking instrument - Google Patents

Abstract

PURPOSE:To remove a speed error in a coast speed and prevent a target from being missed even when the target is hidden by an obstacle during a tracking by changing the time constant of a filter in correspondence with time elapsing from the initiation of the tracking. CONSTITUTION:The time constant of a variable time constant filter 17 is small at the time when a tracking is initiated and the output of the variable time constant filter 17 is adjusted to speed signals 7 in a short time. Since the time constant of the variable time constant filter 17 is increased with an elapsed time 16 and a speed error involved in the speed signals 7 is removed, no speed error is produced in a coast speed 11 when a target is extinguished. Thus, the target is enabled not to be missed even when the target is hidden by an obstacle during the tracking.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tracking device that automatically tracks a target using an imaging device such as a television camera.

[Conventional technology]

FIG. 2 is a diagram showing an example of a conventional tracking device, in which (1) in FIG. 9 is the target, C2) is the target +11, and the image signal (
3), (4) is the visual axis of the imager (2), (5) is the tracking command signal, (61 is the tracking command signal (5)
After this occurs, a speed detector detects the angular velocity of the center of gravity of the target (11) from the image signal (3) and outputs it as a speed signal (7), (8) is the obstacle, (9I is the target (11 is the obstacle
Ql is the extinction signal that is output from the speed detector +61 when it enters the shadow of image signal 8) and disappears from among the 9 image signals (3). sample hold circuit that holds and outputs as coast speed dll (12 is extinction signal (9
A switch that outputs a speed signal (]) when 1 is not output, and outputs a coast speed Q11 when a disappearance signal is output, (I3 is a speed command signal, (I4 is a speed command for the imager (2) This is a driver that rotates at the speed of signal qj.

Next, the operation will be explained.

In the tracking device configured as shown in Fig. 2, when the target (1) moves, the angular velocity of the target (1) is detected by the speed detector (61) as a speed signal (7), and the angular velocity of the target (1) is detected as a speed signal (7) by the Imager +21 is rotated by driver α4 at an angular velocity of target +11, so imager (2)
The visual axis line (4) of will continue to face the direction of the target rll.

Next, the target (41) enters the shadow of the obstacle (8) and the image signal (3
), the target angular velocity just before the disappearance is outputted from the sample hold circuit 01 as a coasting velocity Qυ, and when the imager (2+) is rotated at the coasting speed α■, even if the target (1) is not visible, the imager ( 21 visual axes (4)
can continue facing the direction of the target [1].

Furthermore, when the target (11) passes through the shadow of the obstacle (8) and reappears, the visual axis (4) of the imager (21) is facing the direction of the target [1], so the imager (2) images the target. It is possible to resume tracking and continue to do so.

[Problems to be Solved by the Invention] However, in the conventional tracking device configured as described above, an error occurs in the coast speed +II) due to the apparent speed change that occurs when the target gradually disappears.

It is not possible to continue pointing the reference line (4) in the direction of the target (11) while the target disappears, and even if the target 111 appears again, tracking cannot be restarted and the target (1) is lost.

To be more specific, when the target (11) gradually enters the shadow of the obstacle (8), the size of the target (11) gradually decreases from the front.From the above, the center of gravity of the target (11) moves backward. The angular velocity of the center of gravity of the multi-target rl+ apparently decreases.

The coast speed [111] at which the target (1) completely disappears behind the obstacle has an error with respect to the actual attitude of the target (11) due to the apparent speed change.

The above-mentioned error is caused by the visual axis line (41) being oriented in the wrong direction while the target is disappearing.
21 cannot image the target (11) and cannot resume tracking.

This invention was made to solve the above-mentioned problems, and aims to provide a tracking device that does not cause errors in coasting speed when the target disappears.

[Means for solving problems]

The tracking device according to the present invention is provided with a filter whose time constant can be changed, and inputs a velocity signal ( ) to a sample and hold circuit through the filter.

[Effect]

In this invention, the velocity signal (7
) is removed by a filter with a large time constant, and the time constant of the filter is made variable to shorten the time constant immediately after tracking starts, allowing the output of the filter to settle to the target speed in a short time.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention (11 to a4 are the same as in FIG. 2).

0 is a time measuring device that measures the elapsed time after the start of tracking,
ue is the elapsed time, Q71 is a variable time constant filter, and the time constant of the filter is increased in proportion to the elapsed time aS.

In the tracking device configured as described above.

The time constant of the variable time constant filter (L71) at the time of starting tracking is small and the output of the variable time constant filter fin settles to the speed signal (7) in a short time.Furthermore, the time constant of the variable time constant filter αη changes with the elapsed time aF3. Increased speed signal (7)
Since the speed error included in is removed, the coast speed α0 busy speed error when the target disappears does not occur.

〔Effect of the invention〕

As explained above, this invention provides a variable time constant filter, so that even if the target hides behind an obstacle during tracking, there is no speed error in the coast speed and the target is not lost.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of a tracking device according to the present invention;
FIG. 2 is a configuration diagram of a conventional tracking device. In the figure, (1) is the eye (21 is the imager, (3) is the image signal. (4) is the visual axis line, (5) is the tracking command signal, +61 is the speed detector. (7) is the speed signal, +8) is the obstacle, (91 is the extinction signal, (II is the sample hold circuit, Uυ is the coast speed, +12 is the switch, (13 is the speed command signal, (
14i is a driver, (I9 is a time measuring device, eel is an elapsed time,
(One is a variable time constant filter. In FIG. 9, the same or corresponding parts are indicated by the same reference numerals.

Claims (1)

[Claims] an imager that images the target; a speed detector that detects the speed of the target from the output of the imager; a filter that smoothes the speed of the target; a sample hold circuit that holds the output of the filter; In a tracking device consisting of a switch that switches between the target speed and the output of the sample and hold circuit, and a driver that drives the imager using the output of the switch, the time constant of the filter is determined by the elapsed time from the start of tracking. A tracking device that changes according to the