http://yetl.yabesh.ir/yetl1/handle/yetl/19051 2026-04-26T06:47:06Z http://yetl.yabesh.ir/yetl1/handle/yetl/4311042 Design of a 6-DOF Heavy-Duty and High-Precision 3–3 Orthogonal Parallel Robot With Flexible Hinges Qi, Chenkun; Lin, Jianfeng; Hu, Yan; Zhou, Songlin; Gao, Feng Parallel robot is important in high-precision application. The current studies focus on the high-precision robot with light payload capability. It is insufficient for the support of a space optical telescope. When designing a robot with a large payload, performance redundancy of the robot needs to be reduced because the high payload and precision will cause high cost. In this paper, a six degrees-of-freedom heavy-duty and high-precision 3–3 orthogonal parallel robot with flexible hinges is presented. A performance redundance minimization-based type selection method is proposed by the isotropy comparison. The performance of between Stewart and orthogonal mechanisms is compared based on local transmission index, force and torque payload isotropy, displacement, and rotation accuracy isotropy. A performance mean maximization and standard deviation minimum dimensional optimization method is proposed. Two new indexes named payload distribution index and accuracy distribution index are proposed to evaluate the performance redundancy of the mechanism. The mechanism parameters are designed based on performance atlas using workspace volume index, global transmission index, global payload index, global accuracy index, payload distribution index, and accuracy distribution index. A new modeling method considering the nun-functional motion of spherical joints with stiffness compensation is proposed. Modeling and control experiments on the robot demonstrate the effectiveness of the proposed method. 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4311040 Design, Analysis, and Experimental Evaluation of a New Expansion Screw Using Compliant Mechanisms Gan, Jinqiang; Chen, Feng; Ge, Ming-Feng; Lu, Qinghua; Chen, Weilin This article presents a design solution for a new expansion screw based on compliant mechanisms. The new expansion screw applies distributed compliant mechanisms, rhombus amplification mechanisms, and right circular flexure hinges to it. The distributed compliant mechanism realizes the contraction, the rhombus amplification mechanism realizes its expansion and fixation, and the right circular flexure hinges are used to reduce friction. The forces analysis of the new expansion screw when it works is used to calculate its maximum load-bearing capacity. A series of simulations and experiments are carried out to demonstrate the practicability and efficiency of the new expansion screw. In experiments, the new expansion screws using acrylonitrile butadiene styrene (ABS) and nylon plastic are fabricated, respectively, and the expansion screws using nylon plastic already available on the market are set as a comparison. The experimental results indicate that the structure of the new expansion screws is better than the existing expansion screws on the market, and the corresponding overall bearing capacity is more than double than the expansion screw already available on the market. The new expansion screw realizes a significant increase in its bearing capacity and shows a strong application prospect. 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4311039 In Situ Variable Stiffness Strategy for a Planar Tensegrity Manipulator Using Quadratic Programming Chen, Yanghui; Luo, Jiahui; Liu, Jiafu; Xu, Xiaoming; Jiang, Jianping; Chu, Weimeng Tensegrity manipulators are rigid-flexible coupling elastic mechanisms with complex stiffness characteristics. By changing the prestress levels of tensile cables, the manipulators become versatile mechanisms with variable stiffness. This allows them to maneuvering steadily in high stiffness mode during transport tasks while exhibiting good carrying capacity and hold enhanced compliance for interactive safety in lower stiffness mode. However, it is difficult to achieve the desirable pose and desired stiffness simultaneously for tensegrity manipulators due to the strong correlation between the equilibrium pose and the prestress state. This article proposes an in situ variable stiffness strategy for the dual-triangle planar tensegrity manipulator (DTPTM), which can change the manipulator’s stiffness without changing its pose. First, a static model is developed for the tensegrity manipulator under external constraints in terms of natural coordinates. Then, the tangent stiffness matrix is derived and reduced based on the statics model and the corresponding null space matrix. By constructing the objective function, the variable stiffness strategy is established as a quadratic programming problem to vary the stiffness of all joints. On the basis of numerical results, we analyze the range of variable stiffness for the dual-triangle tensegrity (DTT) module and discuss the feasibility of the variable stiffness strategy. Finally, the variable stiffness strategy is verified by various simulation results and validated by hardware experiments of the 2-degrees-of-freedom manipulator prototype. 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4311038 Fast Response Gripper Based on Asymmetric Bistable Dual-Triangle Tensegrity Structure Yang, Wenlong; Luo, Jiahui; Xu, Xiaoming; Liu, Kun; Lu, Zhenbo Robots require compliant actuators capable of reducing tremendous stress shocks while maintaining fast response and lightweight. Bistable tensegrity structures have excellent performances such as fast response and high efficiency. In this study, a novel fast response gripper based on a dual-triangle bistable tensegrity structure was explored. The bistable properties of the dual-triangle tensegrity structure were analyzed from the perspective of the energy landscape. Two optimization methods were employed to adjust the structural parameters of it, aiming to achieve the desired energy landscape and agility properties. One of these optimization methods is innovative, utilizing equilibrium constraints to optimize with higher accuracy and computational efficiency. Its distinguishing feature is the ability to optimize the energy differences of bistable structures in precise equilibrium configurations without the need for discretization. By applying this method, a gripper based on the dual-triangle tensegrity structure was designed. The gripper demonstrated excellent performances in fast response and easy-trigger, verifying the feasibility of this method. This research is significant for developing fast response grippers, morphing structures, and multistable robots, which have potential applications in foldable robots, bird-like micro aerial vehicles, fruit-picking mechanisms, and more. 2025-01-01T00:00:00Z