CN111896027A - A Simulation Modeling Method for Ranging Sensors Considering Terrain Relief - Google Patents

Abstract

The invention relates to a simulation modeling method for a ranging sensor considering terrain fluctuations, which is realized by the following methods: S1. The surface of the star to be measured corresponding to the terrain elevation of the current sub-satellite point is used as a reference plane to determine the location of the ranging beam. The maximum elevation of the terrain within the range; S2. Determine the starting point of the beam search according to the determined maximum elevation of the terrain, perform a rough search according to the preset step size, and search for the intersection of the beam and the terrain. When the height corresponding to a certain position of the beam is less than the terrain height, the dichotomy method is adopted. The intersection of the beam and the terrain is finely searched until the ranging accuracy meets the requirements.

Description

A Simulation Modeling Method for Ranging Sensors Considering Terrain Relief

technical field

The invention relates to a simulation modeling method for a ranging sensor considering terrain fluctuations, and belongs to the technical field of spacecraft guidance, navigation and control. The invention can be applied to the mathematical simulation verification of various extraterrestrial celestial body soft landing detection missions using ranging sensor navigation, and has wide application value and market prospect.

Background technique

As one of the key sensors to ensure the safe landing of the Mars Entry Module, the ranging sensor needs to accurately simulate the distance measurement relative to the ground during the landing process according to the digital terrain to effectively verify the navigation correction based on the ranging sensor. Schemes and Algorithms. During the dynamic descent of the Chang'e series of lunar soft landings, the simulated measurements of the ranging sensors did not consider the influence of terrain fluctuations. For rugged terrain, it is obviously inconsistent with the actual situation without considering the impact of terrain fluctuations on the ranging sensor, and it is difficult to truly verify the system navigation scheme and algorithm. Therefore, it is necessary to inherit the mathematical simulation model of the Chang'e series lunar soft landing ranging sensors. , Design a high-precision ranging sensor measurement modeling method considering the influence of terrain relief.

SUMMARY OF THE INVENTION

The technical problem solved by the present invention is as follows: Aiming at the requirement of accurately simulating the measurement of the ranging sensor during the entry, descent and landing of Mars, a simulation modeling method of the ranging sensor considering the terrain fluctuation is proposed.

The technical solution of the present invention is: a simulation modeling method of a ranging sensor considering terrain fluctuation, which is realized in the following manner:

S1. Use the surface of the star to be measured corresponding to the terrain elevation of the current sub-satellite point as the reference plane, and determine the maximum elevation of the terrain within the terrain range where the ranging beam is located;

S2. Determine the starting point of the beam search according to the determined maximum elevation of the terrain, perform a rough search according to the preset step size, and search for the intersection of the beam and the terrain. When the corresponding elevation of a certain position of the beam is less than the terrain elevation, use the dichotomy method to finely search for the difference between the beam and the terrain. Intersection until the ranging accuracy meets the requirements.

Preferably, S1 is specifically implemented in the following manner:

Determine the longitude and latitude of the intersection of the ranging beam and the reference plane using the ranging sensor installation and the position and attitude information of the lander;

The geographic range of the ranging beam is determined by taking the longitude and latitude of the current sub-satellite point and the longitude and latitude of the intersection of the ranging beam and the datum as the diagonal point of the rectangle;

Search for the maximum elevation of the digital terrain within the range to determine the maximum elevation of the terrain within the terrain range where the ranging beam is located.

Preferably, the latitude and longitude of the sub-satellite point of the ranging sensor lon0, lat0 and the

The height h of the sensor to the sub-satellite point:

r _SF =[r _SFx r _SFy r _SFz ] ^T =r _F +C _FB r _S

lon0=atan2(r _SFy ,r _SFx )

h＝||r _SF ||-h _Terrain (lon0,lat0)

Among them, ||·|| represents the vector modulo operation, r _F is the position vector of the lander in the fixed coordinate system of the star to be measured, and C _FB is the transformation matrix from the coordinate system of the lander body to the fixed coordinate system of the star to be measured. , r _S is the installation position of the ranging sensor in the coordinate system of the lander body, r _SF is the position of the ranging sensor in the fixed coordinate system of the star to be measured, [r _SFx r _SFy r _SFz ] ^T is the value of r _SF Three components, h _Terrain (lon0, lat0) represents the terrain elevation at latitude and longitude lon0, lat0.

Preferably, the latitude and longitude loni, lati of the intersection of the i-th ranging beam and the reference plane are determined in the following manner

loni=arctan2(r _SiFy ,r _SiFx )

Among them, r _SiF is the position of the intersection of the ith beam of the ranging sensor and the reference plane in the fixed coordinate system of the star to be measured, [r _SiFx r _SiFy r _SiFz ] ^T is the three components of r _SiF , r _SF is the measurement The position of the distance sensor in the fixed coordinate system of the star to be measured, C _FB is the transformation matrix from the coordinate system of the lander body to the fixed coordinate system of the star to be measured, and d _Si is the ith beam of the ranging sensor on the lander. Pointing in the body coordinate system, h is the height from the ranging sensor to the sub-satellite point.

Preferably, the maximum elevation of the terrain within the terrain range where the ranging beam is located is determined in the following manner:

h _TerrainMaxi =max(h _Terrain (lon,lat))lon0≤lon≤loni and lat0≤lat≤lati

Among them, lon0 and lat0 are the longitude and latitude of the sub-satellite point of the ranging sensor, loni and lati are the longitude and latitude of the intersection of the i-th beam of the ranging sensor and the reference plane, and max( ) represents the maximum value operation.

Preferably, the beam search starting point r _SiF0 is determined in the following manner:

Among them, || · || represents the vector modulo operation, h _TerrainMaxi is the maximum elevation of the terrain within the terrain range of the ranging beam, C _FB is the transformation matrix from the lander body coordinate system to the fixed coordinate system of the star to be measured, d _Si is the orientation of the i-th beam of the ranging sensor under this system, and r _SF is the position of the ranging sensor in the fixed coordinate system of the star to be measured.

Preferably, the rough search process is as follows:

Calculate the position r _SiFj and its corresponding longitude and latitude lonij, latij in the direction of beam i during the jth search according to the following formula

r _SiFj =r _SiF0 +(j·Δl)C _FB d _Si =[r _SiFjx r _SiFjy r _SiFjz ] ^T

lonij=arctan2(r _SiFjy ,r _SiFjx )

If ||r _SiFj ||-h _Terrain (lonij,latij)≤0, stop the search, and the position of the intersection of beam i and terrain is r _SiFj from rough search, otherwise, assign the value of j+1 to j to continue the next search, until the r _SiFj that satisfies the condition is obtained;

In the above formula ||·|| represents the vector modulo operation, r _SiF0 is the starting point of beam search, C _FB is the transformation matrix from the coordinate system of the lander body to the fixed coordinate system of the star to be measured, and d _Si is the first range of the ranging sensor. The pointing of i beams under this system, Δl is the rough search step size, [r _SiFjx r _SiFjy r _SiFjz ] ^T is the three components of r _SiFj , h _Terrain (lonij, latij) represents the terrain elevation at the latitude and longitude lonij, latij .

Preferably, the coarse search step Δl is determined as follows:

Among them, ||·|| represents the vector modulo operation, h _TerrainMaxi is the maximum elevation of the terrain within the terrain range where the ranging beam is located, h _Terrain (lon0, lat0) represents the terrain elevation at the latitude and longitude lon0, lat0, C _FB is from the landing is the transformation matrix from the coordinate system of the sensor body to the fixed coordinate system of the star to be measured, d _Si is the direction of the i-th beam of the ranging sensor under this system, and r _SF is the fixed coordinate system of the distance sensor under the fixed coordinate system of the star to be measured. The position of , max(·) represents the operation of taking the maximum value.

Preferably, the fine search process is as follows:

Perform the kth fine search according to the following formula to obtain the position r _SiFjk in the direction of beam i and its corresponding latitude and longitude lonijk, latijk;

when k=0

r _SiFj0 =r _SiFj

lonij0=lonij

latij0=latij

When k>0

lonijk=arctan2(r _SiFjky ,r _SiFjkx )

in

时停止搜索，此时置r_SiFjk即为波束i与地形交点位置，其中ξ为要求的测距精度；when

Stop searching when , and set r _SiFjk to be the position of the intersection of beam i and terrain, where ξ is the required ranging accuracy;

In the above formula ||·|| represents the vector modulo operation, r _SiFjk-1 is the position in the direction of beam i obtained by the k-1 search, and C _FB is the fixed coordinate system from the lander body coordinate system to the star to be measured. d _Si is the direction of the i-th beam of the ranging sensor under the system, Δl is the coarse search step, k is the number of fine searches, h _Terrain (lonijk,latijk) represents the terrain at lonijk, latijk longitude and latitude Elevation.

Preferably, the distance measurement value l _i of the ranging beam i is calculated by the following formula:

l _i =||r _SiFjk -r _SF ||

In the formula, r _SiFjk is the position of the intersection of beam i and terrain in the fixed coordinate system of the star to be measured under fine search; r _SF is the position of the ranging sensor in the fixed coordinate system of the star to be measured.

The beneficial effects of the present invention compared with the prior art are:

Aiming at the requirement of accurately simulating the measurement of the ranging sensor during the entry, descent and landing of Mars, the present invention designs a strategy for determining the maximum elevation of the terrain within the range of the beam of the ranging sensor, which greatly reduces the search range of the intersection between the beam and the terrain. Searching the intersection of ranging beam and terrain to determine ranging measurement lays the foundation; a fast and precise search strategy for the intersection of ranging sensor beam and terrain is designed. Accurately simulate the distance measurement along the direction of the ranging beam, so that the key technologies such as the navigation scheme and algorithm based on the ranging sensor can be verified more realistically and effectively through mathematical simulation.

Description of drawings

Fig. 1 is a flow chart of the present invention.

Detailed ways

The present invention will be further described below with reference to the embodiments and accompanying drawing 1 . The present invention is a simulation modeling method of a ranging sensor considering terrain fluctuation, and the steps are as follows:

The first step is to determine the maximum elevation of the terrain within the range of the ranging sensor beam

Taking the terrain surface corresponding to the terrain elevation of the current sub-satellite point as the reference plane, and using the installation of the ranging sensor and the position and attitude information of the lander to determine the longitude and latitude of the intersection of the ranging beam and the reference plane; The longitude and latitude of the intersection of the beam and the reference plane are the diagonal corners of the rectangle to determine the geographic range of the ranging beam, and the maximum elevation of the digital terrain within this range is searched to determine the maximum elevation of the terrain within the geographic range of the ranging beam.

Define r _F as the position vector of the lander in the fixed coordinate system of the star to be measured, C _FB as the transformation matrix from the coordinate system of the lander body to the fixed coordinate system of the star to be measured, and r _S as the ranging sensor in the lander body. The installation position in the coordinate system, d _Si is the pointing of the i-th beam of the ranging sensor in this system.

(1) Calculate the latitude and longitude lon0, lat0 corresponding to the sub-satellite point of the ranging sensor and the height h from the ranging sensor to the sub-satellite point according to the position of the lander and the installation of the ranging sensor

Where ||·|| represents the vector modulo operation, [r _SFx r _SFy r _SFz ] ^T is the three components of r _SF , h _Terrain (lon0, lat0) represents the terrain elevation at the latitude and longitude lon0, lat0.

(2) Determine the longitude and latitude loni and lati at the intersection of the ith beam and the reference plane according to the pointing of the ith beam of the ranging sensor under the system;

Among them, r _SiF is the position of the intersection of the ith beam of the ranging sensor and the reference plane in the fixed coordinate system of the star to be measured, and [r _SiFx r _SiFy r _SiFz ] ^T is the three components of r _SiF .

(3) Search and determine the maximum elevation h _TerrainMaxi of the terrain within the range of longitude lon0~loni and latitude lat0~lati

h _TerrainMaxi = max(h _Terrain (lon,lat)) lon0≤lon≤loni and lat0≤lat≤lati (4)

where max(·) represents the maximum value operation, and h _Terrain (lon, lat) represents the terrain elevation at the latitude and longitude lon and lat.

The second step is to determine the intersection of the ranging beam and the terrain

Calculate the starting point position r _SiF0 of the intersection of the search beam i and the terrain according to the maximum terrain elevation h _TerrainMaxi determined in the first step, and roughly search for the intersection of the beam and the terrain with a certain step size Δl along the beam direction from this point. When the corresponding height of a certain position of the beam is less than the terrain elevation, the dichotomy method is used to continue to finely search for the intersection of the beam and the terrain until the ranging accuracy requirements are met.

(1) Determine the starting point of the ranging beam search r _SiF0

(2) Roughly search for the intersection of the beam and the terrain according to the step size Δl

When the jth search is performed, the position r _SiFj (j=0, 1, 2, ...) in the direction of beam i and its corresponding longitude and latitude lonij, latij are obtained

Among them, j is the rough search times, [r _SiFjx r _SiFjy r _SiFjz ] ^T is the three components of r _SiFj , and Δl is the rough search step size.

Δl can be selected from the following range:

Among them, max(·) represents the operation of taking the maximum value.

The value of Δl is not necessarily determined according to the range of the above formula, and can be adjusted according to the terrain conditions. When the terrain fluctuation is small, the rough search step Δl can take a larger value in order to reduce the amount of calculation. Δl takes a small value to prevent the occurrence of ranging beam crossing terrain.

If ||r _SiFj ||-h _Terrain (lonij,latij)≤0, the search is stopped, and the position of the intersection of the beam i and the terrain is r _SiFj from the rough search, otherwise j=j+1 to continue the next search. Among them, h _Terrain (lonij,latij) represents the terrain elevation at lonij and latij in longitude and latitude.

(3) Use the dichotomy method to finely search for the intersection of the beam and the terrain

When the position r _SiFj of the intersection of beam i and terrain is obtained from the rough search, and the position r _SiFjk (k=0, 1, 2, ...) in the direction of beam i is obtained by the kth fine search and its corresponding latitude and longitude lonijk, latijk, then

when k=0

r _SiFj0 =r _SiFj

lonij0=lonij

latij0=latij(8)

When k>0

in

r _SiFjk-1 is the position in the direction of beam i obtained by the k-1 search, C _FB is the transformation matrix from the coordinate system of the lander body to the fixed coordinate system of the star to be measured, d _Si is the i-th ranging sensor The direction of the beam in this system, Δl is the coarse search step size, k is the number of fine searches, h _Terrain (lonijk, latijk) represents the terrain elevation at lonijk, latijk longitude and latitude.

时即可停止搜索，此时置r_SiFjk即为波束i与地形交点位置，其中ξ为要求的测距精度。when

The search can be stopped at this time, and r _SiFjk is set to be the position of the intersection of the beam i and the terrain, where ξ is the required ranging accuracy.

The third step is to calculate the distance measurement value l _{i of the ranging beam i}

l _i =||r _SiFjk -r _SF || (11)

The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims (10)

1. a ranging sensor simulation modeling method considering terrain fluctuation is characterized in that it is realized in the following manner: S1. Use the surface of the star to be measured corresponding to the terrain elevation of the current sub-satellite point as the reference plane, and determine the maximum elevation of the terrain within the terrain range where the ranging beam is located; S2. Determine the starting point of the beam search according to the determined maximum elevation of the terrain, perform a rough search according to the preset step size, and search for the intersection of the beam and the terrain. When the corresponding elevation of a certain position of the beam is less than the terrain elevation, use the dichotomy method to finely search for the difference between the beam and the terrain. Intersection until the ranging accuracy meets the requirements. 2. method according to claim 1, is characterized in that: S1 is realized by following means specifically: Determine the longitude and latitude of the intersection of the ranging beam and the reference plane using the ranging sensor installation and the position and attitude information of the lander; The geographic range of the ranging beam is determined by taking the longitude and latitude of the current sub-satellite point and the longitude and latitude of the intersection of the ranging beam and the datum as the diagonal point of the rectangle; Search for the maximum elevation of the digital terrain within the range to determine the maximum elevation of the terrain within the terrain range where the ranging beam is located. 3. method according to claim 2 is characterized in that: determine the height h of distance measuring sensor sub-satellite point longitude and latitude lon0, lat0 and distance measuring sensor to sub-satellite point in the following manner: r _SF =[r _SFx r _SFy r _SFz ] ^T =r _F +C _FB r _S lon0=atan2(r _SFy ,r _SFx )

h＝||r _SF ||-h _Terrain (lon0,lat0) Among them, ||·|| represents the vector modulo operation, r _F is the position vector of the lander in the fixed coordinate system of the star to be measured, and C _FB is the transformation matrix from the coordinate system of the lander body to the fixed coordinate system of the star to be measured. , r _S is the installation position of the ranging sensor in the coordinate system of the lander body, r _SF is the position of the ranging sensor in the fixed coordinate system of the star to be measured, [r _SFx r _SFy r _SFz ] ^T is the value of r _SF Three components, h _Terrain (lon0, lat0) represents the terrain elevation at latitude and longitude lon0, lat0. 4. The method according to claim 2, characterized in that: the latitude and longitude loni, lati of the intersection of the i-th ranging beam and the reference plane are determined in the following manner

loni=arctan2(r _SiFy ,r _SiFx )

Among them, r _SiF is the position of the intersection of the ith beam of the ranging sensor and the reference plane in the fixed coordinate system of the star to be measured, [r _SiFx r _SiFy r _SiFz ] ^T is the three components of r _SiF , r _SF is the measurement The position of the distance sensor in the fixed coordinate system of the star to be measured, C _FB is the transformation matrix from the coordinate system of the lander body to the fixed coordinate system of the star to be measured, and d _Si is the ith beam of the ranging sensor on the lander. Pointing in the body coordinate system, h is the height from the ranging sensor to the sub-satellite point. 5. The method according to claim 2, characterized in that: the maximum elevation of the terrain within the terrain range where the ranging beam is located is determined in the following manner: h _TerrainMaxi =max(h _Terrain (lon,lat))lon0≤lon≤loni and lat0≤lat≤lati Among them, lon0 and lat0 are the longitude and latitude of the sub-satellite point of the ranging sensor, loni and lati are the longitude and latitude of the intersection of the i-th beam of the ranging sensor and the reference plane, and max( ) represents the maximum value operation. 6. The method according to claim 1, wherein the beam search starting point r _SiF0 is determined in the following manner:

Among them, || · || represents the vector modulo operation, h _TerrainMaxi is the maximum elevation of the terrain within the terrain range of the ranging beam, C _FB is the transformation matrix from the lander body coordinate system to the fixed coordinate system of the star to be measured, d _Si is the orientation of the i-th beam of the ranging sensor under this system, and r _SF is the position of the ranging sensor in the fixed coordinate system of the star to be measured. 7. method according to claim 1 is characterized in that: described rough search process is as follows: Calculate the position r _SiFj and its corresponding longitude and latitude lonij, latij in the direction of beam i during the jth search according to the following formula r _SiFj =r _SiF0 +(j·Δl)C _FB d _Si =[r _SiFjx r _SiFjy r _SiFjz ] ^T lonij=arctan2(r _SiFjy ,r _SiFjx )

If ||r _SiFj ||-h _Terrain (lonij,latij)≤0, stop the search, and the position of the intersection of beam i and terrain is r _SiFj from rough search, otherwise, assign the value of j+1 to j to continue the next search, until the r _SiFj that satisfies the condition is obtained; In the above formula ||·|| represents the vector modulo operation, r _SiF0 is the starting point of beam search, C _FB is the transformation matrix from the coordinate system of the lander body to the fixed coordinate system of the star to be measured, and d _Si is the first range of the ranging sensor. The pointing of i beams under this system, Δl is the rough search step size, [r _SiFjx r _SiFjy r _SiFjz ] ^T is the three components of r _SiFj , h _Terrain (lonij, latij) represents the terrain elevation at the latitude and longitude lonij, latij . 8. The method according to claim 7, wherein: the coarse search step Δl is determined in the following manner:

Among them, ||·|| represents the vector modulo operation, h _TerrainMaxi is the maximum elevation of the terrain within the terrain range where the ranging beam is located, h _Terrain (lon0, lat0) represents the terrain elevation at the latitude and longitude lon0, lat0, C _FB is from the landing is the transformation matrix from the coordinate system of the sensor body to the fixed coordinate system of the star to be measured, d _Si is the direction of the i-th beam of the ranging sensor under this system, and r _SF is the fixed coordinate system of the distance sensor under the fixed coordinate system of the star to be measured. The position of , max(·) represents the operation of taking the maximum value. 9. The method according to claim 1, wherein: the fine search process is as follows: Perform the kth fine search according to the following formula to obtain the position r _SiFjk in the direction of beam i and its corresponding latitude and longitude lonijk, latijk; when k=0 r _SiFj0 =r _SiFj lonij0=lonij latij0=latij When k>0

lonijk=arctan2(r _SiFjky ,r _SiFjkx )

in

when

Stop searching when , and set r _SiFjk to be the position of the intersection of beam i and terrain, where ξ is the required ranging accuracy; In the above formula ||·|| represents the vector modulo operation, r _SiFjk-1 is the position in the direction of beam i obtained by the k-1 search, and C _FB is the fixed coordinate system from the lander body coordinate system to the star to be measured. d _Si is the direction of the i-th beam of the ranging sensor under the system, Δl is the coarse search step, k is the number of fine searches, h _Terrain (lonijk,latijk) represents the terrain at lonijk, latijk longitude and latitude Elevation. 10. The method according to claim 1, wherein the distance measurement value l _i of the ranging beam i is calculated by the following formula: l _i =||r _SiFjk -r _SF || In the formula, r _SiFjk is the position of the intersection of beam i and terrain in the fixed coordinate system of the star to be measured under fine search; r _SF is the position of the ranging sensor in the fixed coordinate system of the star to be measured.

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