In the deployable mechanism for a conventional truss antenna, the nodes cannot be adjusted to be uniform in attitude. To solve this problem, a method of adding constraint chains is proposed based on the reciprocal screw theory. By performing type synthesis of the deployable mechanisms for the truss antenna, a novel deployable mechanism is developed that not only enables complete folding and unfolding but also allows the attitude of the nodes to be made uniform. First, according to the unit division of the antenna reflection surface and the characteristic motions of the nodes, constraint chains that can be added between two adjacent nodes are synthesized based on the reciprocal screw theory. Second, to improve the overall rigidity of the mechanism, a series of basic developable unit mechanisms is obtained by adding virtual constraint chains, again based on the reciprocal screw theory. Next, a method of dividing the minimum combination unit of the curved-surface antenna mechanism is proposed. The design of the minimum combination unit mechanism is optimized, such that the attitude of all nodes in the final folded state can be made consistent. Finally, the feasibility of the optimized minimum combination unit mechanism is verified by simulation analysis. The proposed method for type synthesis provides a new approach to the design of deployable mechanisms for truss antennas, and novel deployable mechanisms for the curved-surface truss antenna with better performance are obtained.

Recently, the truss antennas with deployable tetrahedron unit mechanisms have been successfully applied in orbit, owing to the advantages of large calibers, high accuracy, and large folding ratios. As multiloop coupled mechanisms, deployable tetrahedral mechanisms have multiple different output links, whose supporting limbs connecting output links and the base are mutually coupled. These mechanisms are also called the passive-input overconstrained mechanisms because their passive torsion springs are used as drivers and because the number of the drivers contained is more than the degrees of freedom (DOFs). In this work, a method based on the equivalent concept of first link-removing and then restoring is proposed for the DOF analysis of the multiloop coupled deployable tetrahedral mechanisms. With one coupled chain removed, the equivalent serial chains between the coupled components and the base are established in the remainder of the mechanisms. Then, the coupled chain removed is restored and the equivalent of the multiloop coupled mechanisms is obtained. The Lagrange method is used to establish the dynamic equation of the passive-input overconstrained mechanisms; the influence of the stiffness and number of torsion springs on the unfolding motion is examined.

Deployable mechanism with preferable deployable performance, strong expansibility, and lightweight has attracted much attention because of their potential in aerospace. A basic deployable pyramid unit with good deployability and expandability is proposed to construct a sizeable deployable mechanism. Firstly, the basic unit folding principle and expansion method is proposed. The configuration synthesis method of adding constraint chains of spatial closed-loop mechanism is used to synthesize the basic unit. Then, the degree of freedom of the basic unit is analyzed using the screw theory and the link dismantling method. Next, the three-dimensional models of the pyramid unit, expansion unit, and array unit are established, and the folding motion simulation analysis is carried out. Based on the number of components, weight reduction rate, and deployable rate, the performance characteristics of the three types of mechanisms are described in detail. Finally, prototypes of the pyramid unit, combination unit, and expansion unit are developed to verify further the correctness of the configuration synthesis based on the pyramid. The proposed deployable mechanism provides aference for the design and application of antennas with a large aperture, high deployable rate, and lightweight. It has a good application prospect in the aerospace field.

To meet the needs of large load and high reliability measurement under complex working conditions and downsize the outline of six-axis force sensor as much as possible, the design concept of hybrid limb is proposed to the design of parallel six-axis force sensor. A kind of heavy-load-bearing flexible integrated six-axis force sensor with hybrid limbs is proposed. The proposed force sensor adopts a hybrid-limb configuration integrating eight measuring redundant limbs and four load-bearing limbs. It is capable of measuring 5500 N vertical force, 3000 N horizontal force, 160 N·m moment about the vertical axis, and 130 N·m moment about the horizontal axis. Based on the superposition principle under small deformation, the whole stiffness matrix of force sensor and the analytical mapping relation are constructed, respectively. The accuracy of the theoretical modeling is verified by the stress analysis of the designed sensor using finite element method software ANSYS. Finally, the prototype is calibrated, and the results show that it has good linearity.

Cable-driven continuum robots exhibit excellent capabilities in the unstructured environment due to their inherent compliance and dexterity. To improve the reliability and load capacity of continuum robots, increasing the number of cables is often used in the control of continuum robots. However, the number of actuators will increase with the cables. To tackle this challenge, this work proposes a method for increasing the number of cables without increasing actuators in a continuum robot through parallel platforms. The parallel platforms are used to control all the cables in the continuum robot and can be separated from the continuum robot to enable the remote drive of a manipulation arm by using the cable-tube structure. The manipulation arm is composed of several independent bending modules in series, which can be configured freely according to the demand of degrees-of-freedom. Further, each bending module is controlled independently by a parallel platform, which can avoid the mutual interference between the cables of one bending module and another one, improve the position accuracy and simplify the control difficulty of the manipulation arm. To evaluate the proposed method, this work develops a prototype of six-cable-driven continuum robot controlled by 3RPS parallel platforms and presents some basic kinematic models to describe its function, and then an experimental work characterizing its performance. Experimental results illustrated the importance of increasing the number of cables, the rationality of kinematic models of the continuum robot, and the feasibility of controlling multiple cables by a parallel platform.