Design and multi-objective comprehensive optimization of cable-strut tensioned antenna mechanism

Highlights

• A new type of cable-strut tensile deployable antenna mechanism is proposed.

• The antenna mechanism is designed with multi-objective integrated optimization.

• The lightweight design of deployable mechanism unit is realized.

• The antenna configuration with optimal stiffness and mass synthesis characteristics is obtained by genetic algorithm.

• The expand-fold function test and dynamic performance test are carried out on the prototype.

Abstract

In this study, a new type of cable-strut tensioned antenna mechanism is proposed and subjected to multi-objective optimization. First, a series of new cable-strut tension element configurations is proposed, and the optimal configurations are optimized on the basis of six topological characteristics of stable spatial cable-strut tensioned structures. Second, the mathematical surrogate models between configuration parameters, structural parameters, and fundamental frequencies of antenna mechanisms are established with the response surface method. Third, the optimization of the antenna mechanism synthesis is established, and the antenna configuration with optimal stiffness and mass synthesis is obtained with a genetic algorithm. Finally, the correctness and rationality of the proposed structural configuration is verified by developing a 2 m caliber prototype and conducting a dynamic characteristic test. The results should serve as a useful reference for the design of large caliber satellite antennas in aerospace engineering.

Introduction

With the implementation of China's space programs, including manned spaceflight, deep space exploration, space-based observation, and space attack and defense, the demand for various large deployable antenna mechanisms has become increasingly urgent. Existing large deployable antennas adopt a truss-type mechanism. Inflatable antennas have several advantages, including light mass and large folding ratio. However, their industry application remains limited because of issues in their structural stability, shape surface accuracy, space environment adaptability, and others. Therefore, a new cable-strut tensioned antenna mechanism with high stiffness and low mass should be developed.

The existing types of deployable antennas in orbit can be divided into ring, frame, plane, rib, and tension types. The ring antenna is composed of a developable ring truss and a parabolic prestressed cable network system in the interior [1,2]. From 2000 to 2007, five AstroMesh ring antennas have been used in three types of spacecraft for in-orbit applications [3,4]. Ring antennas are ideal large deployable antennas because of their high toughness, high thermal stability, small folded volume, and simple structure [[5], [6], [7]]. Georgian's Experiment Geodesic Satellite(EGS) deployable antenna is a shear fork-type framework with a profile accuracy of up to 2.1 mm; it exhibits an umbrella-like shape from the center to the periphery [[8], [9], [10]]. In 2006, the Japan Aerospace Exploration Agency(JAXA) deployed a space modular truss antenna on Engineering Test Satellite VIII(ETS-VIII) [[11], [12], [13]]. The Synthetic Aperture Radar(SAR) antenna is a typical application case of a planar antenna. In 1978, National Aeronautics and Space Administration(NASA) launched Seasat with a resolution of 25 m [14]. European Space Agency(ESA) launched civilian radars the first European Remote Sensing Satellite(ERS-1) and the second European Remote Sensing Satellite(ERS-2) in 1991 and 1995, respectively; and Environmental Satellite (ENVISAT), an earth environment monitoring satellite with a spatial resolution of 30 m, in 2002 [15,16]. The Canadian Space Agency launched Radarsat-1 in 1995 and Radarsat-2 in 2007 [17]. Japan launched the earth observation satellite Advanced Land Observing Satellite (ALOS) in 2006 with a maximum resolution of 2.5 m [18]. The Jet Propulsion Laboratory (JPL) proposed three design concepts: gas-filled phase array, gas-filled reflection array, and frame support [19,20]. In 2001 JPL, L′ garde, and International Latex Corporation (ILC) Dover developed a planar thin-film antenna with a size of 2.3 m × 1 m [21,22]. In 1997, an 8 m ribbed antenna was deployed on Highly Advanced Laboratory for Communication and Astronomy (HALCA) [23,24]. The most typical example is the tension-deployable antenna designed by Harris [25]. Table 1 lists the typical large antennas successfully applied in orbit.

With the rapid growth of the aerospace industry, deployable antennas have become ultra-large in size, reaching tens or even hundreds of meters in diameter. The Innovative Space Based Radar Antenna Technology project, funded by DARPA (Defense Advanced Research Projects Agency), has developed a large-aperture antenna, the spread–yield ratio is as high as 100:1 [26]. Harris developed a Maypole Hoop and Column deployable antenna (15 m diameter) mechanism and conducted the corresponding ground test and in-orbit expansion function test [27]. The Maypole Hoop and Column antenna at the center of the column and the outer truss antenna layout through the upper and lower layers of the tension cable are linked together to form a balanced space state, with the antenna playing a supporting role through its improved rigidity, small volume, and light weight that make it suitable for large-scale antennas; the ring-type antenna currently in orbit measures approximately 50–100 m [27]. A Georgian–Russian company designed a shear fork-type double antenna. The agency's outer truss is composed of a fork scissor mechanism, and the central hub is connected to the outer support truss by a tensioned membrane rib [28,29]. The large elliptical satellites currently in orbit with deployable antennas, such as the American TRUMPET (90 m in diameter), MERCURY (105 m in diameter), and Jumpseat (150 m in diameter), have deployable double-layer ring trusses. Professor Guan Fuling of Zhejiang University designed a prototype of a two-layer ring truss deployable antenna with a diameter of 2 m [30,31]. Gilger L et al. proposed a cable-strut tensile double-loop deployable antenna mechanism, whose inner layer is a ring deployable truss mechanism and whose outer layer is tensioned with an extension rod and a rope; this composition improves the stiffness of the whole antenna mechanism [32]. DLR and ESA conducted collaborative research and eventually developed a film with an area of 40 m² and a total mass of less than 60 kg [33].

The mass of a single-layer ring truss deployable antenna, which is characterized by a light mass and large folding ratio, is not proportional to an increase in diameter. However, the larger the diameter of the antenna is, the smaller the stiffness of the single-layer ring truss is, and the worse the shape and surface accuracy are. In terms of rigidity, the double-layer annular truss deployable antenna mechanism can be fully applied to large-diameter antenna mechanisms, but it suffers from large mass and low dynamic stiffness. The tensed deployable mechanism is light weight and has a high folding rate, but it is prone to issues such as low structural stiffness, poor anti-interference ability, and vibration attenuation. No existing deployable antenna mechanism can meet the technical requirements of future space missions for ultra-large space deployable structures. The advantages of the double-layer ring truss deployable antenna mechanism and tensegrity mechanism should be combined to overcome their respective disadvantages and obtain a new lightweight space deployable mechanism. Therefore, the current study follows the principle of structural symmetry and node–force balance in developing flexible cables that are not easily wound and have the highest specific element stiffness. These flexible cables are used to replace a number of members in deployable quadrangle prismatic elements. A series of new cable-strut tensile element configurations is also proposed to realize the lightweight design of deployable mechanism elements. The cable-strut tensile-type ring antenna mechanism is large in size and has a low stiffness. It is also characterized as nonlinear with rigid–flexible coupling. Therefore, flexible cable nonlinearity for dynamic analysis should be considered to solve the multi-objective comprehensive optimization of antenna mechanisms. On the basis of the dynamic characteristics of a large deployable antenna mechanism, a dynamic mathematical surrogate model is established in this work to facilitate engineering use so as to establish a comprehensive optimization model of the antenna mechanism, optimize the overall performance of the antenna mechanism, and identify the configuration with the best performance.

The rest of this paper is organized as follows. In Section 2, the optimal configuration to realize the lightweight design of deployable mechanism elements is selected. In Section 3, the mathematical surrogate models of the antenna mechanism are established. In Section 4, the comprehensive optimization of the antenna mechanism is carried out. In Section 5, a prototype of a 2 m caliber antenna is designed. The expansion and collection function test and dynamic characteristic test are carried out to verify the rationality of the analysis of the configuration.