Cable Net Reflector Research Articles

Minimization of Cable-Net Reflector Shape Error by Target-Approaching and Procedural-Learning Method

Minimization of Cable-Net Reflector Shape Error by Target-Approaching and Procedural-Learning Method

Surface Reconfiguration Method of Mesh Antennas by Electrical Performance

The active shape adjustment of large-diameter mesh antennas has been widely explored for achieving high on-orbit performances. The surface reconfiguration of the cable net reflector is the essential precondition for active shape adjustment of mesh antennas. In this paper, we proposed a surface reconfiguration method based on the modal theory and transfer learning method. The proposed surface reconfiguration method was divided into three steps. The first step is that the axial error distributions of preselected points of the cable net reflector is derived analytically by the electromechanical coupling method together with far-field mapping. The second step uses a modal theory to predict axial mechanical deformations of discrete nodes of cable net reflectors by the derived axial errors of preselected points. In the last step, the transfer learning theory together with the deep learning algorithm is adopted to predict radial mechanical deformations of discrete nodes of cable net reflectors. Simulation and comparative results show the proposed surface reconfiguration method can accurately predict displacement deformations of mesh antennas.

Structural design, dynamic analysis, and verification test of a novel double-ring deployable truss for mesh antennas

This study proposes a novel deployable antenna consisting of a double-ring deployable truss and a cable net reflector, intended for large mesh antennas. The structural design of deployable antennas is presented, and the geometric relationship is formulated. Compared with the same type of antennas, the storage ratio of the double-ring deployable antenna is significantly improved, especially the storage ratio in the height direction. Meanwhile, the stiffness is also improved. Considering the influence of the cable net structure, a dynamic model is established using Lagrange's equation and the driving force for deployment is analyzed from the perspective of work. Finally, a 5-m prototype is fabricated to demonstrate the feasibility of the proposed structure and carry out the experiments. The deployment tests show that the antenna can be driven by driving cable to deploy successfully, the surface accuracy is also tested and the results show good repeatability of the double-ring deployable antenna.

Conceptual design of a new thermal‐electric conversion device in lightweight concentrating solar thermal power system

AbstractConcentrating solar thermal power (CSTP) technology has become a hot issue in the present research because of its high conversion efficiency. However, traditional schemes cannot be widely applied due to their complex structure, low power density, and high cost. In view of this, based on a new type of lightweight cable mesh reflector structure and the Rankine cycle, a new conceptual design of thermal‐electric conversion device in CSTP system is proposed. The process of thermal‐electric conversion is actualized through smart and lightweight structural design; the performance estimation of the device is carried out through focusing performance analysis and thermodynamic analysis; the cycling feasibility is verified through multifield coupling simulation analysis. Compared with the existing thermal‐electric conversion devices, the device proposed in this paper has higher power‐to‐weight ratio. And the power generation system that combines the proposed device with the flexible cable net reflector has the characteristics of lightweight, portability, and small land area, which has a great significance for the popularization and application of distributed layout CSTP system.

Time‐dependent radiation pattern analysis of cable‐net reflector antennas

Due to the time-dependent load-elongation characteristic of cables, the cable-net reflector antenna shows a creep and recovery behaviour which has limited the development of the cable-net reflector antenna with high frequency and high stability. Therefore, this study is dedicated to investigating a time-dependent radiation pattern analysis method for cable-net reflector antennas. Based on the physical optics (PO) method, formulas are firstly established for the time-dependent far-field radiated pattern analysis. To avoid the repetitive computation of PO radiation integrals and improve the calculation efficiency, the exponential error terms are expanded by the Taylor series at the mean values of phase errors in each small region and the time factor is separated from the integral for some special case. Eventually, an axis-symmetric reflector antenna is taken as a numerical example to verify the practicability, validity and robustness of the proposed method.

Minimization of Cable-Net Reflector Shape Error by Machine Learning

During assembly of a cable-net reflector, surface adjustments must be made to meet the stick accuracy requirement of a space mission by changing the lengths of adjustable cables. It is desirable to find the optimum adjustment amount based on the current state of the cable-net reflector. However, all data needed to establish an accurate simulation model for the cable-net reflector cannot be measured. Therefore, the cable-net reflector is treated as a black box, and a machine learning algorithm (support vector machine) is used to develop a prediction model to establish the relationship between cable length adjustments and surface accuracy. The -fold cross-validation method is used to estimate the generalization error. The simulated annealing and grid search are combined to get the optimum hyperparameters for the prediction model. Next, a surface adjustment method is developed to calculate the optimal cable lengths. A tension truss reflector example is used to demonstrate the support vector machine prediction model and the adjustment method. The machine learning algorithm identified the relationships between cable lengths and surface accuracy. Both surface accuracy and tension uniformity can be improved by adjusting the boundary cables and tension ties with this method using only information from the front-side nodes.

Form Finding of Cable Net Reflector Antennas Considering Creep and Recovery Behaviors

This paper investigates a whole process for the form-finding analysis of cable net reflector antennas with creep and recovery behaviors in consideration. Both the force-density and nonlinear finite element methods are extended together to establish and solve the nonlinear optimization model for the form-finding analysis. First, the equal force-density method is applied to the form-finding analysis of the initial cable net configuration, in which the creep and recovery behaviors are not taken into account. Second, the nonlinear force-density method and Schapery’s nonlinear viscoelastic theory are used to build the mathematical model of the creep and recovery behaviors of cable net reflector antennas, and the incremental-iterative method is then adopted to solve such a mathematical model. Based on aforementioned two steps, the nonlinear optimization model is established, and it is solved by the inverse iteration algorithm. Eventually, the hoop truss reflector antenna is presented as a numerical example to illustrate the efficiency of the proposed method for the form-finding design of the creep and recovery behaviors of cable net reflector antennas.

Modal Analysis and Active Vibration Control of a Cable-Net Reflector

A cable-net reflector is fist introduced and then the state space representation is derived based on the finite element model. Modal analysis is carried out for the purpose of vibration control in modal space. The first several natural frequencies and vibration modes are obtained to analyze the vibration characteristics. The optimal control theory based on LQR with full state feedback is used for the control problem. Numerical simulations of the impulse disturbance response and the frequency response are implemented. Also, the contrast between the uncontrolled and controlled cases is illustrated. The theoretical results confirm the effectiveness of the proposed active control strategy for the vibration suppress of the cable-net reflector.

A general method for active surface adjustment of cable net structures with smart actuators

Active surface adjustment of cable net structures is becoming significant when large-size cable net structures are widely applied in various fields, especially in satellite antennas. A general-duty adjustment method based on active cables is proposed to achieve active surface adjustment or surface profile reconfiguration of cable net structures. Piezoelectric actuators and voice coil actuators are selected for constructing active cable structures and their simplified mechanical models are proposed. A bilevel optimization model of active surface adjustment is proposed based on the nonlinear static model established by the direct stiffness method. A pattern search algorithm combined with the trust region method is developed to solve this optimization problem. Numerical examples of a parabolic cable net reflector are analyzed and different distribution types of active cables are compared.

Pretension Design of Space Mesh Reflector Antennas Based on Projection Principle

AbstractA pretension design method based on the projection principle is proposed for space deployable mesh reflector antennas. First, the equilibrium tension of the plane cable net structure is obtained by a force equilibrium method. Then, the obtained cable tensions of the plane cable net structure are projected to the spatial cable net reflector to obtain the spatial cable tensions. Finally, the implication relationship between the plane cable tensions and the tension distributions of front and back cable nets is revealed. A general analytical expression is deduced for the axisymmetric reflector, and an optimization model is established for the offset reflector. Some hoop truss deployable mesh antennas are examined as examples of pretension design. The uniform cable tensions and high surface accuracy of reflectors are obtained to verify the effectiveness of the proposed method.

Mechatronic method for study of random error on cable‐net reflector antennas

A mechatronic method for the study of cable-net reflector antennas under mechanical random error is presented. In this method, the reflector mechanical random error and electrical radiation performance are taken as random variables, such that the electrical radiation performance based probability is analysed. A useful mathematical expression between the numerical characteristics of electrical radiation performance and mechanical parameters are developed. Applications on two cable-net reflector antennas are described and the simulation results demonstrate the effectiveness of the proposed method in the random error evaluation.

Nonlinear dynamic analysis of space cable net structures with one to one internal resonances

The nonlinear dynamic analysis of cable net structures becomes more and more significant for their space applications required high surface accuracy, especially mesh reflector antennas. In this work, the resonant multi-modal dynamics due to 1:1 internal resonances in the finite-amplitude vibrations of cable net structures subjected to harmonic loads are investigated. The nonlinear dynamic equation of space cable net structures is first developed using the extended Hamilton principle, which belongs to the self-excited vibration with quadratic and cubic nonlinearities. Linear modal analysis is then performed to decouple the nonlinear differential equations, and yields a complete set of system quadratic/cubic coefficients. With the aim of parametrically revealing nonlinear behaviors of space cable net structures, the second-order asymptotic analysis under 1:1 internal resonance is accomplished by the method of multiple scales. The nonlinear phenomena of a planar cable net and cable net reflector, such as the bending of response curve, jump phenomena, instability regions, saddle-node bifurcation, are verified by means of numerical analysis.

Form-Finding Analysis and Active Shape Adjustment of Cable Net Reflectors with PZT Actuators

High-precision cable net reflectors are widely required for future communications and observations. Concerning the improvement of their surface accuracy, the active cable structure constructed by incorporating a piezoelectric (PZT) actuator into flexible cables has been proposed to achieve active shape control or active correction of the reflector surface. Two design stages of the cable net reflector with active cables, the form-finding analysis and active shape adjustment, are investigated. The form-finding analysis is derived from nodal force equilibrium equations by the minimum norm method-solving linear equations. An active shape adjustment method with the aid of active cables is then proposed to find the actuation voltages of PZT actuators for the prescribed shape. The adjustment method is divided into three parts: a finite-element model of the active cable net reflector, an active adjustment optimal model, and its solving method using the multidimensional advance-retreat algorithm. Finally, numerical examples of a parabolic cable net reflector are analyzed. Simulation results demonstrate that the proposed methods can warrant cable tension forces, which fall into a specified range, and the deformed cable net reflector surface can match the one designed by PZT actuators.

Development of a Novel Double-Ring Deployable Mesh Antenna

This paper addresses a type of deployable mesh antenna consisting of the double-ring deployable truss edge frame and the cable net reflector. The structural design concept of the deployable antennas is presented. The deployable truss is designed and the geometric relationship of each strut length is formulated. Two types of radial truss elements are described and compared. The joint pattern and the active cables of the final design concept are determined. The pattern of the cable net is the three-orientation grid. Two connection schemes between the reflector and the deployable edge frame are investigated. The design parameters and the shape adjustment mechanism of this cable net are determined. The measurement test technologies of the antennas on the ground including test facilities, deployment test, and measurement and adjustment test are proposed. The antenna patterns are analyzed based on the real surfaces of the reflector obtained by the reflective surface accuracy measurement. The tests and analytic results indicated that the accuracy of the reflective surface is high and is suitable for low-frequency communication.