CN106569223B

CN106569223B - Gamma off-machine sensor emitter cone angle 120 DEG plus-minus 10 DEG distance measuring method

Info

Publication number: CN106569223B
Application number: CN201610894785.0A
Authority: CN
Inventors: 陈熙萌; 邵剑雄; 吴世通; 黄伟; 韩承志; 闫学文; 罗伟; 周满; 刘靖雷; 杨爱香
Original assignee: Lanzhou University
Current assignee: Lanzhou University
Priority date: 2016-10-14
Filing date: 2016-10-14
Publication date: 2020-04-21
Anticipated expiration: 2036-10-14
Also published as: CN106569223A

Abstract

The invention discloses a method for measuring the distance of a gamma shutdown sensor by increasing or decreasing 10 degrees at a 120-degree cone angle of a transmitter, wherein the gamma shutdown sensor comprises the transmitter and a receiver, the transmitter sends gamma rays downwards along the cone angle and reflects the gamma rays through the ground, the receiver receives the gamma rays reflected by the ground, and distance measurement is realized according to the relation between the distance and the strength of the received gamma ray signals. The distance measuring method of the gamma shutdown sensor has stable and superior distance measuring performance, can accurately measure the actual distance of the aircraft from the ground, and is less influenced by the shape of the landing ground.

Description

Gamma off-machine sensor emitter cone angle 120 DEG plus-minus 10 DEG distance measuring method

Technical Field

The invention belongs to the technical field of remote sensing, and particularly relates to a method for measuring a distance by increasing or decreasing a cone angle of 120 degrees by 10 degrees by a gamma shutdown sensor transmitter.

Background

In the field of aerospace deep space exploration in China, the implementation of soft landing of an aircraft on extraterrestrial stars becomes one of the key problems to be solved for extraterrestrial star exploration.

Wherein the precise measurement of the exact distance between the aircraft and the planet ground is one of the core technologies,

the existing one-way transmitting distance measuring performance is not stable and superior enough, the actual distance between an aircraft and the ground cannot be measured accurately, and the influence of the landed ground appearance is large; and the short-distance measurement is not accurate under the complex and severe environment of extraterrestrial stars.

Disclosure of Invention

The embodiment of the invention aims to provide a method for measuring the distance of a gamma off-sensor transmitter with a cone angle of 120 degrees plus or minus 10 degrees, and aims to solve the problems that the one-way transmitting distance measurement performance is not stable and excellent enough, the actual distance of an aircraft from the ground cannot be accurately measured, meanwhile, the influence of the landed ground shape is large, and the short-distance measurement is inaccurate in a complicated and severe environment of extraterrestrial stars.

The invention is realized in this way, a gamma shutdown sensor distance measuring method, the gamma shutdown sensor includes two parts of emitter and receiver, the emitter sends gamma ray downwards along the taper angle and reflects through the ground, the receiver receives the gamma ray reflected by the ground, realizes distance measurement according to the relation between the distance and the received gamma ray signal intensity; the signal strength decreases exponentially with increasing distance, and the relationship between distance and signal in this ranging method is represented by the following equation:

H=D*EXP*(A+B*X+C*X²)

in the above formula, H is height (distance), X is signal strength (count), and D, A, B, C is a parameter for different environmental usage modes.

Further, the emitter is made of a Cs-137 source, and the receiver is a NaI receiving detector.

Further, the preferred transmit cone angle of the transmitter is 120 ° ± 10 °.

The distance measuring method guarantees the strength of the returned measured signal to the maximum extent; minimizing external environmental interference, (e.g., cosmic background radiation in the outer space environment, the topography of the outer star, etc.); the influence of the gamma ray on an aircraft and the environment is minimized while the accurate distance measurement is ensured.

The distance measuring method of the gamma shutdown sensor has stable and superior distance measuring performance, can accurately measure the actual distance of the aircraft from the ground, and is less influenced by the shape of the landing ground.

The invention mainly solves the problem of short-distance accurate distance measurement under the complex severe environment of extraterrestrial stars, is suitable for measuring the distance level of 0-100 meters, and has the characteristics of small ground morphology interference resistance and small environmental influence in the cone angle transmission of the transmitter in comparison with unidirectional transmission.

Drawings

FIG. 1 is a simplified simulation model of a gamma off-sensor transmitter according to an embodiment of the present invention;

FIG. 2 shows the counting variation of the receiver under different ground conditions and different transmitter transmission cone angles according to the embodiment of the present invention;

FIG. 3 is a count of the difference in vertical distance (Δ Y) between the receiver and the transmitter provided by an embodiment of the present invention;

FIG. 4 is a graph of counts at different horizontal distances (Δ X) between a receiver and a transmitter provided by an embodiment of the present invention;

in the figure: 1. a receiver; 2. a transmitter; 3. and (5) cement ground.

FIG. 5 shows an embodiment of the present invention providing receivers and transmitters at different horizontal distancesΔXDifferent vertical distancesΔYA counting graph is arranged;

FIG. 6 shows the overall height of the transmitter and receiver when the relative positions of the transmitter and receiver are fixed according to an embodiment of the present inventionHA count map of changes.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The application of the principles of the present invention will now be further described with reference to the accompanying drawings.

Please refer to fig. 1 to 4:

the gamma off-sensor transmitter cone angle 120 plus-minus 10 degree distance measurement method provided by the embodiment of the invention, as shown in fig. 1, includes a transmitter 1 and a receiver 2, the transmitter is made of a Cs-137 source, the receiver is a NaI receiving detector,

the working principle provided by the embodiment of the invention is as follows:

in fig. 1, the transmitting cone angle of the transmitter is 120 °, and the distance is measured according to the strength of the received signal.

The transmitter 1 emits gamma rays downwards along a cone angle, the gamma rays are transmitted and scattered in air or a vacuum space, and after reaching a medium surface (such as the ground), the gamma rays are reflected by the ground, so that gamma photons are scattered and received by the receiver 2 above, and thus, the record is recorded, when the distance is short, the record signal of the receiver is strong, and otherwise, the record signal of the receiver is weak. Distance measurement can be realized according to the relation between the distance and the signal strength, and after relevant calibration work is completed, the device can be used for accurately measuring the distance, and the accuracy reaches cm magnitude.

The signal strength decreases exponentially with increasing distance, and the relationship between distance and signal in this ranging method is represented by the following equation:

H=D*EXP*(A+B*X+C*X²)

The working principle of the present invention is further explained below with reference to specific embodiments.

1. The distance measurement performance of the transmitter cone angle design is stable

Compared with a unidirectional emission design mode, the cone angle design is less influenced by the appearance of a landing interface. Digging a pit of 20cm by 1) below the emitter; 2) leveling the ground; 3) the three conditions of placing a 20cm by 20cm stone were compared, and the results are shown in FIG. 2. (a) The receiver count under the transmitter with the cone angle of 120 degrees of the full transmission angle changes along with the elevation; (b) the receiver counts with the elevation changes under the unidirectional transmitter.

The conclusion can be drawn that the cone angle emission distance measurement performance is stable and superior, the actual distance between the aircraft and the ground can be accurately measured, and the influence of the landed ground shape is small.

2. The distance measurement performance of the transmitter in the vicinity of the cone angle of 120 degrees is optimal:

the results in fig. 3 and 4 show that the transmitter cone angle is the strongest signal reception acquisition area in the range of 120 °, which accounts for 90% -97% of the return signal.

Fig. 3 (a) counts when H =3m, Δ X =84cm, Δ Y =9cm, (b) counts when H =3m, Δ X =84cm, Δ Y =29 cm;

in fig. 4, (a) counts when H =3m, Δ X =34cm, and Δ Y =19cm, and (b) counts when H =3m, Δ X =134cm, and Δ Y =19 cm.

It can be concluded that the transmitter cone angle is designed around 120 deg. and most of the signals scattered back through the ground etc. can be obtained, thus the distance between the aircraft and the landing ground can be accurately obtained.

Considering the influence of the gamma rays on aircraft devices as small as possible, reducing the source emission angle as possible and simultaneously considering the accuracy of the measurement distance, wherein the optimal range of the emitter emission cone angle is 120 degrees +/-10 degrees.

FIG. 5 shows a receiver and a transmitter at different horizontal distances according to an embodiment of the present inventionΔXDifferent vertical distancesΔYThe lower counting chart is selected according to 120 degrees, the counts of the receivers and the transmitters are basically not changed along with the change of the cone angle after 120 degrees when the receivers and the transmitters are placed at different positions and intervals or at different landing distances and heights, the vicinity of 120 degrees can be used as a critical point, and the preferable scheme of 120 degrees is also selected according to the invention. With the ray intensity minimized, 120 ° ± 10 ° will be the optimal value range.

FIG. 6 illustrates the overall height of the transmitter and receiver when the relative positions of the transmitter and receiver are fixedHThe above demonstrates that receiver counts are substantially insensitive to relative position between the transmitter and receiver, and that count rate trends are approximately the same, although there may be slight differences in counts at different positions. Meanwhile, the counting of the receiver in the gamma ranging is used for measuring the height of the whole model machine from the cement floorHAnd is also less sensitive, the receiver count is relatively stable against the trend of transmitter cone angle changes at various heights.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A gamma shutdown sensor emitter taper angle 120 plus-minus 10 degree range finding method is characterized in that the gamma shutdown sensor comprises an emitter and a receiver; the emitter is used for emitting gamma rays downwards along a cone angle and reflecting the gamma rays through the ground;

the receiver is used for receiving gamma rays reflected by the ground, and realizing distance measurement according to the relation between the distance and the strength of the received gamma ray signals, and the relation between the distance and the strength of the received gamma ray signals is expressed as follows:

H＝D*EXP*(A+B*X+C*X²)

in the above formula, H is height, X is signal intensity, and D, A, B, C is different environment use mode parameters;

the emitter is made of a Cs-137 source, and the receiver is a NaI receiving detector;

the emitter has a transmit cone angle of 120 ° ± 10 °.