Disclosure of Invention
The invention aims to avoid the defects of the prior art and provides a method for constructing a multi-section unfolding arm of a satellite-borne mesh antenna, which can meet the size limitation of a rocket carrying space and reasonably construct the unfolding arm according to actual conditions.
In order to achieve the purpose, the invention adopts the technical scheme that: a method for constructing a multi-section unfolding arm of a spaceborne mesh antenna comprises the following steps
Establishing a standard reflecting surface under a global coordinate system (X, Y, Z) with a given focal length f and a given caliber D of a reflecting surface of the mesh antenna and an origin of coordinates O, and generating an offset reflecting surface according to an offset distance D' of the reflecting surface of the mesh antenna;
secondly, determining the coordinates of key nodes A and B of the net-shaped antenna upper net surface under a global coordinate system according to the standard reflecting surface and the bias reflecting surface, and calculating the height H of the net-shaped antenna upper net surfaceup;
Step three, the height H of the lower net surface of the net-shaped antenna is givendownAnd the distance H' between the upper mesh surface and the lower mesh surface, calculating the overall height H of the mesh antenna;
step four, according to the overall height H of the mesh antenna obtained through calculation, under a global coordinate system, calculating the coordinates of a root node C of the offset reflecting surface, namely the tail end node of the unfolding arm;
step five, according to the feed source position of the mesh antenna and the root node C coordinate of the offset reflector obtained in the step four, the minimum total length of the unfolding arm is taken as a target, and the position constraints of the mesh antenna reflector and the unfolding arm are combined to construct the number N and the arm length L of the multi-section unfolding arm
iAnd under the global coordinate system, the included angle between the jth node of the unfolding arm and the X axis
And obtaining the included angle theta between the two expansion arms
k;
Step six, constructing the multi-section unfolding arm according to the step five, wherein when two connecting rods connected by a hinge are in a theta shapekWhen the unfolding arm joint is locked.
Further, the step one of generating the offset reflecting surface specifically includes:
establishing a standard reflecting surface under a global coordinate system (X, Y, Z) with a coordinate origin as a point O, and taking a cylindrical axial direction D with an offset distance of D' as an X axial direction of an (XOZ) surface of the global coordinate system (X, Y, Z)aAt said DaAnd D/2 is taken as the radius to generate a cylinder, and the intersecting line of the cylinder and the standard reflecting surface is the offset reflecting surface of the mesh antenna.
Further, the second step is specifically as follows:
the standard reflecting surface can be expressed as an equation under a global coordinate system:
the focal length f of the antenna reflecting surface is the focal length of the reflecting surface;
on the (XOZ) plane of the global coordinate system (X, Y, Z), two intersection points of the bias reflecting plane and the standard reflecting plane are key nodes of the net surface on the net antennaA and B, establishing coordinates of a network key node A on the mesh antenna as (X) under a global coordinate systemA,YA,ZA) And B has the coordinates of (X)B,YB,ZB):
Y is Y since the world Wide Key Point coordinates are on the (XOZ) plane of the Global coordinate System (X, Y, Z)AAnd YBIs 0 and XAAnd XBCan be expressed as:
on said (XOZ) plane, the equation of the straight line AB is thus established, which can be expressed as:
ZAB=KAB(XAB-XA)+ZA,
wherein KABThe slope of line AB can be expressed as:
in the global coordinate system, the distance between the node on the offset reflecting surface and the line segment AB is recorded as HNFrom the point-to-line distance formula, one can obtain:
for the obtained HNThe function is derived and extremed, when X is d', HNObtaining a maximum value, and calculating to obtain:
is obtained byHeight H of the upper net surfaceup。
Further, the second step further includes calculating the height H of the mesh surface of the mesh antennaupThe integrity verification step of (1): according to key nodes A and B of the upper net surface of the mesh antenna, taking the cylindrical axis D with the offset distance as DaAnd (3) establishing a local coordinate system (x, y, z) of the offset reflecting surface at an intersection point o of the line segment AB and taking the tangential direction and the normal direction of the point as the axial directions of the local coordinate systems x and z, and completely coinciding the projections of the upper mesh surface and the lower mesh surface in the (xoy) plane in the local coordinate system to ensure the integrity of the mesh antenna.
Further, the third step is specifically:
the overall height H of the mesh antenna may be expressed as:
H=Hup+Hdown+H′。
the mesh antenna comprises an upper mesh surface, a lower mesh surface and a vertical cable net, wherein the upper mesh surface of the mesh antenna determines the electrical property of the antenna, and the lower mesh surface of the mesh antenna is given only for meeting the structural requirement.
Further, the fourth step is specifically:
coordinate (X) of the deployment arm root node CC,YC,ZC) Since the C point coordinates are on the (XOZ) plane of the global coordinate system (X, Y, Z), Y isCIs 0, according to the geometric relationship, XCAnd ZCCan be expressed as:
i.e. the coordinates of point C on the (XOZ) plane of the global coordinate system (X, Y, Z).
Further, the fifth step is specifically:
according to the coordinates of the feed source point F (0, 0, F) and the coordinates of the expansion arm tail end node C, the rod length connected with the point C must be larger than the whole height H of the mesh antenna, P is the distance from the key node A to the rod length, and for convenient installation, the distance must be between the values
PAnd
in the number of the unfolded arms N and the length of the unfolded arms L
i(i 1.... N) and the j-th node of the unfolding arm form an angle with the X-axis
For design variables, with the goal of minimizing the sum of all rod lengths, the following optimization model is established:
wherein d is a design variable, L is the sum of the lengths of the unfolding arms, and X
1And Z
1Respectively an X coordinate and a Z coordinate of the F point under the global coordinate system, X
N+1And Z
N+1Respectively are the X coordinate and the Z coordinate of the C point under the global coordinate system,
is the largest loadable dimension of the fairing,
kand
the upper limit and the lower limit of the slope of the connection line between the nth node and the (N + 1) th node are respectively expressed as follows:
the angle between the two arms is denoted as θ
k(k 1...., N-1), which can be expressed as:
furthermore, multisection exhibition arm through locking mechanism lock and expand the arm joint, expansion arm joint refer to the hinge that is equipped with between two liang of single-section arms of expansion arm, locking mechanism include be equipped with the draw-in groove on the hinge, still include the connecting rod, the one end of connecting rod is connected on expansion arm, the other end of connecting rod is equipped with the horizontal pole perpendicular with the connecting rod expansion arm hinge free rotation time, the connecting rod does not constitute the constraint relation with the hinge, two expansion arms when hinged joint are thetakAnd when the hinge is closed, the cross rod falls into the clamping groove to lock the hinge.
The invention has the beneficial effects that: the invention aims at minimizing the total length of the unfolding arm, applies corresponding constraint, simultaneously completes the design of the rod number and the length of the joints of the unfolding arm and the included angle between the joints based on an optimized design method, and ensures that the envelope requirement of the carrying fairing can be met when the multiple sections of unfolding arms are folded; at the same timeAfter the included angle of the unfolding arm is obtained based on the optimization design method, when the two connecting rods connected by the hinge are in a theta shapekWhen the telescopic antenna is used, the hinge is locked, and the perfect matching of the focal positions of the reflecting surfaces of the antenna feed source and the mesh antenna is ensured after the multi-section unfolding arm is unfolded in place and locked.
Detailed Description
The principles and features of this invention are described below in conjunction with the following drawings, the examples of which are set forth to illustrate, but are not to be construed to limit the scope of the invention.
The construction method of the multisection unfolding arm of the satellite-borne mesh antenna provided by the invention can establish the construction parameters of the unfolding arm of the mesh antenna in a limited space through calculation as long as the focal length f, the caliber D and the offset distance D' of the reflecting surface of the given mesh antenna are input, and the constructed unfolding arm parameters enable the perfect matching of the focal positions of the reflecting surfaces of the antenna feed source and the mesh antenna when the mesh antenna is actually unfolded and used. In order to achieve the above object, the present invention provides the following embodiments:
example 1: as shown in fig. 1, 2, 3 and 4, a method for constructing a multi-section unfolding arm of a space-borne mesh antenna includes
Step one, a focal length f and a caliber D of a reflecting surface of a mesh antenna are given, a standard reflecting surface is established under a global coordinate system (X, Y, Z) with a coordinate origin as a point O, and a cylindrical shaft with an offset distance D' is taken in the X axial direction of an (XOZ) surface of the global coordinate system (X, Y, Z)To DaAt said DaAnd D/2 is taken as a radius to generate a cylinder, and the intersecting line of the cylinder and the standard reflecting surface is used for generating the offset reflecting surface of the mesh antenna.
Secondly, determining the coordinates of key nodes A and B of the net-shaped antenna upper net surface under a global coordinate system according to the standard reflecting surface and the bias reflecting surface, and calculating the height H of the net-shaped antenna upper net surfaceupThe specific calculation steps are as follows:
the standard reflecting surface can be expressed as an equation under a global coordinate system:
the focal length f of the antenna reflecting surface is the focal length of the reflecting surface;
on the (XOZ) surface of the global coordinate system (X, Y, Z), two intersection points of the bias reflecting surface and the standard reflecting surface are key nodes A and B of the upper net surface of the mesh antenna, and under the global coordinate system, the coordinate of the key node A of the upper net surface of the mesh antenna is established as (X, Y, Z)A,YA,ZA) And B has the coordinates of (X)B,YB,ZB):
Y is Y since the world Wide Key Point coordinates are on the (XOZ) plane of the Global coordinate System (X, Y, Z)AAnd YBIs 0 and XAAnd XBCan be expressed as:
on said (XOZ) plane, the equation of the straight line AB is thus established, which can be expressed as:
ZAB=KAB(XAB-XA)+ZA,
wherein KABThe slope of line AB can be expressed as:
in the global coordinate system, the distance between the node on the offset reflecting surface and the line segment AB is recorded as HNFrom the point-to-line distance formula, one can obtain:
for the obtained HNThe function is derived and extremed, when X is d', HNObtaining a maximum value, and calculating to obtain:
namely, the height H of the upper net surface is obtainedup。
Step three, the height H of the lower net surface of the net-shaped antenna is givendownAnd the distance H' between the upper mesh surface and the lower mesh surface, calculating the overall height H of the mesh antenna, and expressing the overall height H as the following formula:
H=Hup+Hdown+H′。
step four, according to the overall height H of the mesh antenna obtained by calculation, under a global coordinate system, calculating the coordinates of a root node C of the offset reflecting surface, namely the end node of the deployment arm, and the specific steps are as follows:
coordinates (X) of the deployment arm end node CC,YC,ZC) Since the C point coordinates are on the (XOZ) plane of the global coordinate system (X, Y, Z), Y isCIs 0, according to the geometric relationship, XCAnd ZCCan be expressed as:
i.e. the coordinates of point C on the (XOZ) plane of the global coordinate system (X, Y, Z).
Step five, constructing the number N and the arm length L of the multi-section unfolding arms according to the coordinates F (0, 0, F) of the feed source position points of the mesh antenna and the coordinates C of the root nodes of the offset reflecting surfaces obtained in the step four
iAnd under the global coordinate system, the j-th node of the unfolding arm forms an included angle with the X axis
And obtaining the included angle between the two expansion arms as theta
kThe method comprises the following specific steps:
aiming at the minimum total length of the unfolding arm, combining the position constraint of the reflecting surface of the mesh antenna and the unfolding arm, ensuring that the rod length connected with the point C is larger than the overall height H of the mesh antenna, P is the distance from the key node A to the rod length, and the distance is required to be between the numerical value for convenient installation
PAnd
in the number of the unfolded arms N and the length of the unfolded arms L
i(i 1.... N) and the j-th node of the unfolding arm form an angle with the X-axis
For design variables, the following optimization model is established with the goal of minimizing the sum of all rod lengths:
wherein d is a design variable, L is the sum of the lengths of the unfolding arms, and X
1And Z
1Respectively an X coordinate and a Z coordinate of the F point under the global coordinate system, X
N+1And Z
N+1Respectively are the X coordinate and the Z coordinate of the C point under the global coordinate system,
is the largest loadable dimension of the fairing,
kand
the upper limit and the lower limit of the slope of the connection line between the nth node and the (N + 1) th node are respectively expressed as follows:
the angle between the two arms is denoted as θ
k(k 1...., N-1), which can be expressed as:
step six, constructing the multi-section unfolding arm according to the step five, wherein when two connecting rods connected by a hinge are in a theta shapekWhen the unfolding arm joint is locked.
The specific operation example is as follows:
1. simulation parameters
A typical structure of a mesh antenna with some offset feed is shown in fig. 2. The caliber D is 10m, the focal diameter ratio is 0.6m, and the offset distance D' is 5 m.
2. Simulation content and results
Given HdownAnd H' is respectively 1.04m and 0.2m, the height of the antenna is calculated to be 2.2m, the coordinate of the root node C is calculated according to the height of the antenna, and an optimization model is established and solved according to the position of the feed source and the coordinate C of the key node on the obtained mesh antenna. To simplify the operation, the simulation case specifies that all the rod lengths and the included angles between the joints are equal.
The solved key parameters are shown in table 1, and the unfolding joint morphology schematic diagram is shown in fig. 3.
| Number of rods/piece
|
3
|
| Length of pole/m
|
2.83
|
| Included angle theta/DEG
|
155.65 |
The invention provides a design method of a multi-section unfolding arm of a large satellite-borne netted expandable antenna, which ensures that the requirement of carrying a fairing for enveloping can be met when the multi-section unfolding arm is folded, and meanwhile, the design method can become key equipment for supporting the netted antenna and a satellite body after being unfolded. Meanwhile, the invention only carries out structural and mechanism scheme design and does not consider mechanical property.
Example 2: the same as the embodiment 1, except that the method further comprises the step of calculating the mesh antenna upper net surface obtained in the step twoHeight H ofupThe integrity verification step of (1): according to key nodes A and B of the upper net surface of the mesh antenna, taking the cylindrical axis D with the offset distance as DaAnd (3) establishing a local coordinate system (x, y, z) of the offset reflecting surface at an intersection point o of the line segment AB and taking the tangential direction and the normal direction of the point as the axial directions of the local coordinate systems x and z, and completely coinciding the projections of the upper mesh surface and the lower mesh surface in the (xoy) plane in the local coordinate system to ensure the integrity of the mesh antenna.
Example 3: as shown in fig. 5, the same as embodiment 1, except that the multi-section unfolding arm of the present invention locks the unfolding arm joint through a locking mechanism, the unfolding arm joint is a hinge 6 arranged between every two single-section arms 8 of the unfolding arm, the locking mechanism comprises a slot 61 arranged on the hinge 6, and further comprises a connecting rod 7, one end of the connecting rod 7 is connected to the unfolding arm, the other end of the connecting rod 7 is provided with a cross rod 71 perpendicular to the connecting rod 7, when the unfolding arm hinge 6 rotates freely, the connecting rod 7 and the hinge 6 do not form a constraint relation, and when the two unfolding arms connected by the hinge 6 are in a θ shapekWhen the hinge is closed, the cross rod 71 falls into the clamping groove 61 to lock the hinge 6. In the prior art, various structures for locking the unfolding arm exist, and compared with the prior art, the locking structure provided by the invention is simpler and more practical.
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, but rather as the subject matter of the invention is to be construed in all aspects and as broadly as possible.