DE102016003152A1 - Hit sensor for target - Google Patents

Abstract

Method and device for detecting hits on targets or folding discs.
The invention has for its object to reliably detect hits on targets, using all current bullet caliber, and thereby dense vorbebeischüsse or rockfall, as it occurs when close shot in front of the target in the ground, safely hide.
According to the invention, this object is achieved by a filter -F2- filters out the typical sounds that occur when the bullet pierces the target, and the threshold from which a hit is detected on the overall volume and / or another filter value -F3- occurring Noise is adjusted.
The structure is shown in Figure 1.
S1 - Sensor for signal acquisition
V1 amplifier
F1 - Blocking filter for suppression of resonances
F2 - Bandbass filter for recording of breakdown sounds
F3 - Bandpass filter to capture the reference
G1 and G2 rectifier to form the envelopes
BW1 rating level
Z1 - timer
MP1 - Microprocessor as replacement of the framed components
SP1 - Signal processor to replace the framed components

Description

State of the art

Are known hit sensors for targets based on acceleration sensors or piezoelectric transducers DE 31 22 287 , The sensors can each be provided with downstream high-pass or band-pass filters in analog or digital form. These are connected to the targets, made of wood, z. As plywood, hardboard or plastic, z. As polyethylene, etc. may exist. In the patents DE 20 57 414 A . US 6,367,800 B1 or the US 32,123 E Hit sensors are described which use a plurality of sensors for result detection. Essential in such hit sensors is the reliable detection of hits and their distinction from brief passing shots or rockfall. The detection of the hits is carried out by detecting the output signal, a sensor or pickup. The problem is that the measurement signal differs considerably depending on the ammunition calibers, disc sizes and materials as well as the firearms used. This ultimately leads to the fact that for reliable detection of a hit, the sensor and the associated evaluation electronics must be precisely adapted to the disk dimension, materials and in particular the weapons and ammunition types used. If a suitably equipped shooting range is to be used, for example, for another weapon type, the corresponding components must be exchanged and adapted to the modified weapons, ammunition or disc types and materials. Due to the described problems, the conventional sensors are also highly temperature-dependent in their tripping characteristics, which makes their use in the range of strong temperature differences problematic.

From the patent DE 10 2008 059 189 B4 is a hit sensor known which filters out the typical high frequencies with a high-pass filter, which arise when penetrating the target. Vorbeischüsse produce, by a pressure wave which carries the projectile with it, only relatively low frequencies. The sensor therefore makes it easy to distinguish hits from passing shots. However, the sensor fails in case of rockfall and gives this wrong way as a hit. The sensor has a blocking filter in the input stage. Incidentally, the patent states that this filter would serve to amplify the resonance frequencies. It is correct, however, that this filter filters out signals that arise due to a self-resonance of the housing.

Disclosure of the invention

It is therefore an object of the invention to realize a hit sensor that detects without further specific settings with respect to the caliber or the material of the target or folding disc sure hits and close Vorbeischüsse or stone chipping, which arise in bombardment of the soil (gravel) in front of the target can, fades out. Such a hit sensor is required to control folding discs during firing exercises and to count hits.

If a bullet breaks through a target at a speed of 300 meters per second and a length of 10 mm, this process lasts only 33.3 Mico seconds. It therefore arises when penetrating the target only a very short-term noise. A subsequent longer-lasting rattling in the target arises in a similar form even with nearby passing shots and / or rockfall.

Filter circuits, including digital filters, now have the property that your input and release time, with their quality or with the edge steepness and thus with increasing frequency selection increases.

Before a high-quality filter vibrates, the typical noise produced by a bullet penetrating a target is already over.

Therefore, for evaluating and measuring the frequencies that occur when penetrating the target, only low-quality filters and thus short settling times can be used. This has the disadvantage that even frequencies that are far above and / or below the filter frequency, the filter undergo attenuated.

As a result of the aforementioned problem, arbitrary frequencies which occur with high amplitude can trigger a hit detection since they pass through the filter with a still sufficient amplitude. For convenience, the hit sensor must be attached to the bottom of the target's mount. A dense pass by at the foot of the target (close to the sensor) is therefore easily recognized as a hit, because the Vibrations that occur during the pass by, reach the sensor with a high amplitude value. This is especially true for rockfalls, as by rockfall signals with very high amplitudes are triggered. A hit in the head area, however, is often not recognized, although the typical signals occur while penetrating, but only greatly attenuated reach the sensor due to the large distance to the sensor and thus do not exceed the threshold.

According to the invention, this problem is solved by the reference threshold is not set to a fixed value, but is adjusted at each shot event depending on the overall volume or a suitable frequency range.

The basic structure is shown in Figure 1.

A sensor -S1- is attached to the holder of the target for signal detection. This sensor can be a structure-borne sound microphone, an acceleration sensor or a piezo. The amplitude of the detected signal (sound event) is first amplified by the amplifier -V1-. This is followed, first, by a filter -F1- of the signals which are produced by strong natural resonances of the mechanical structure. Natural resonances can produce such strong vibrations both when hit and when passing by that they can interfere with the evaluation. By filtering out these natural resonances, therefore, the signal distance, between hits and dense passby, is significantly improved. Then two more filters are switched. The filter -F2- is tuned to the typical noises that occur when penetrating the target. The filter -F3- is a broadband filter designed to capture the overall volume of the sound event. In the following rectifiers -G1- and -G2- the envelope of the output signals of the filters -F2- and -F3- is formed. The envelopes are compared in a rating level -BW1-. When the signal from filter -F2- reaches a percentage of the signal from filter -F3-, a hit is selected. A subsequent timer -Z1- then generates a pulse of fixed length. The evaluation stage -BW1- and the timer -Z1- can also be realized by a microprocessor -MP1-. The entire circuit, with the exception of the sensor for signal detection and the first amplifier -V1-, can also be realized by a fast signal processor -SP1-.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3122287 [0001]
• DE 2057414 A [0001]
• US 6367800 B1 [0001]
• US 32123 E [0001]
• DE 102008059189 B4 [0002]

Claims (5)

A method and apparatus for detecting targets on targets, characterized in that a bandpass filter is tuned to the frequencies that typically arise when penetrating the target from the projectile, and the threshold from which a hit is selected via a second filter and / or on the the entire amplitude of the detected signal is adjusted for each event, so that only one hit is selected when the typical frequencies of a hit exceed a minimum amplitude in relation to the total amplitude of the signal or to the amplitude of a fixed frequency range. A method and apparatus according to claim 1, characterized in that a further frequency filter is connected upstream to attenuate dominant natural resonances of the signal pickup and / or the sensor housing to achieve an improved signal distance between hit and Vorbeischuss. Method and device according to claim 1 or 2, characterized in that the output signals of the filters are evaluated by a microprocessor which outputs a time-dependent pulse as an output signal or another suitable signal. A method and apparatus according to claim 1 to 3, characterized in that a suitable signal processor is used, which makes both the filter and the subsequent evaluation by software and also outputs a suitable signal. Method and device according to Claims 1 to 4, characterized in that two or more filter circuits are used to form the threshold value.

Images