Mechanism and Machine Theory最新文献_第3页

A bi-level geometrical optimization framework for tailoring kinetostatic behavior of compliant bistable mechanisms 柔性双稳机构动静态行为裁剪的双层几何优化框架

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2026-01-03 DOI: 10.1016/j.mechmachtheory.2025.106338

Tinghao Liu , Ming Zhou , Guangbo Hao

Compliant bistable mechanisms possess two distinct stable equilibrium configurations and can remain in either state without continuous external energy input, making them attractive for compact and energy-efficient applications. However, many existing designs are constrained by limited design flexibility due to simple geometries or are highly sensitive to manufacturing errors. Lumped-compliance mechanisms provide a balanced solution, combining ease of fabrication, moderate complexity and tunability. Leveraging these advantages, this work proposes a bi-level optimization framework to tailor the kinetostatic behavior of bistable mechanisms. For upper level, heuristic algorithms are applied to explore distinct configurations of bistable mechanisms, while the lower level employs the CoSCME method to evaluate large-deformation kinetostatic responses for each candidate configuration. The framework is demonstrated in two case studies that target bistable mechanisms with symmetric switching forces and approximately linear negative stiffness. The optimized designs are further validated through nonlinear FEA simulations and experimental tests, confirming the accuracy and practical feasibility of the approach. This study thus establishes a performance-driven and extensible methodology for compliant mechanism design, with promising applications in multistable structures, mechanical metamaterials, and programmable systems.

柔性双稳态机构具有两种不同的稳定平衡结构，并且可以在没有连续外部能量输入的情况下保持任一状态，这使得它们具有紧凑和节能应用的吸引力。然而，许多现有的设计由于简单的几何形状或对制造误差高度敏感而受到设计灵活性有限的限制。集总遵从性机制提供了一个平衡的解决方案，结合了易于制造、中等复杂性和可调性。利用这些优势，本工作提出了一个双级优化框架来定制双稳态机构的动静力行为。在上一级，启发式算法用于探索双稳机构的不同构型，而在下一级，采用CoSCME方法来评估每个候选构型的大变形动静力响应。该框架在两个具有对称开关力和近似线性负刚度的目标双稳态机构的案例研究中得到了证明。通过非线性有限元仿真和实验测试，进一步验证了优化设计的正确性和实际可行性。因此，本研究建立了一种性能驱动和可扩展的柔性机构设计方法，在多稳定结构、机械超材料和可编程系统中具有良好的应用前景。

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引用次数: 0

Falling dynamics: Accessible saddle and crisis transfer in a passive dynamic Walker 下降动力学：被动动态步行者的可达鞍座和危机转移

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2026-01-03 DOI: 10.1016/j.mechmachtheory.2025.106341

Yumeng Bao , Jianshe Gao , Lei Wan , Qichao Wang , Jianzhuang Zhao , Xiaobo Rao

Falling is a serious consequence of gait disturbances and gait instability in both humans and bipedal walking systems, yet its underlying dynamical mechanisms remain poorly understood. This study systematically identifies and analyzes three distinct falling scenarios in a passive biped robot. The first involves a local bifurcation, in which the period-1 stable gait disappears via a saddle-node bifurcation. The other two are induced by global bifurcations: one triggered by a boundary crisis involving a period-1 saddle, and the other by a more complex double boundary crisis associated with a period-3 saddle. From a global dynamical perspective, these crises are shown to result from transitions between accessible saddle orbits located on the basin boundary—a phenomenon referred to as crisis transfer. To validate these theoretical predictions, a physical robot prototype is developed and tested through both numerical simulations and real-world experiments. The results confirm the predicted gait evolution and fall mechanisms. Overall, these findings offer new insights into the intrinsic dynamics of falling in bipedal systems and provide a theoretical foundation for evaluating and optimizing gait stability and fall prevention strategies.

跌倒是人类和双足行走系统中步态紊乱和步态不稳定的严重后果，但其潜在的动力学机制尚不清楚。本研究系统地识别和分析了被动双足机器人的三种不同的坠落场景。第一种是局部分岔，第一期稳定步态通过鞍节点分岔消失。另外两个是由全局分岔引起的：一个是由涉及时期1鞍的边界危机引发的，另一个是由与时期3鞍相关的更复杂的双边界危机引发的。从全局动力学的角度来看，这些危机是由位于盆地边界的可达鞍轨道之间的过渡造成的，这种现象被称为危机转移。为了验证这些理论预测，开发了一个物理机器人原型，并通过数值模拟和现实世界的实验进行了测试。结果证实了预测的步态进化和跌倒机制。总的来说，这些发现为两足系统跌倒的内在动力学提供了新的见解，并为评估和优化步态稳定性和预防跌倒策略提供了理论基础。

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引用次数: 0

Vibration-based crack diagnosis for asymmetric gears under time-varying operational conditions using a 1-D CNN-LSTM model 基于一维CNN-LSTM模型的非对称齿轮时变工况振动裂纹诊断

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2026-01-03 DOI: 10.1016/j.mechmachtheory.2025.106347

Onur Can Kalay , Fatih Karpat

Gearboxes oftentimes operate under time-varying operating conditions (TVOC). Some studies on TVOC assessed the fluctuations in vibration data through computer simulations, while others appraised healthy gearboxes or piecewise constant operating conditions. Besides, these studies all focus on gears with symmetric tooth profiles. From this standpoint, the present experimental study combined a one-dimensional convolutional neural network (1-D CNN) with a long short-term memory (LSTM) algorithm for diagnosing divergent crack degrees that vary from 0% to 100% with an increment of 25% under TVOC for spur gear pairs with symmetric (20°/20°) and asymmetric (20°/30°) teeth. A series of vibration experiments was performed, considering two TVOC scenarios: (1) variable speed and constant load, and (2) constant speed and variable load. Using an asymmetric profile amplified the amplitude difference between the vibration response of healthy and cracked gears, facilitating fault diagnosis. For different TVOC scenarios, overall accuracies calculated for symmetric gears ranged between 90.005% and 98.654% and between 93.932% and 99.908% for asymmetric ones. The results revealed that the overall classification accuracy could be improved by up to 4.633% using gears with asymmetrical teeth.

变速箱经常在时变工况（TVOC）下运行。一些关于总挥发性有机化合物的研究通过计算机模拟评估了振动数据的波动，而另一些研究则评估了健康的齿轮箱或分段恒定的操作条件。此外，这些研究都集中在对称齿形齿轮上。从这个角度来看，本实验研究将一维卷积神经网络（1-D CNN）与长短期记忆（LSTM）算法相结合，用于诊断对称（20°/20°）和非对称（20°/30°）齿的直齿齿轮副在TVOC下的发散裂纹程度从0%到100%，增量为25%。考虑两种TVOC工况：(1)变速恒载和(2)变速变载，进行了一系列振动实验。利用非对称齿形放大了健康齿轮和裂纹齿轮振动响应的幅值差异，便于故障诊断。对于不同的TVOC场景，对称齿轮计算的总体精度在90.005% ~ 98.654%之间，非对称齿轮计算的总体精度在93.932% ~ 99.908%之间。结果表明，采用非对称齿形齿轮，整体分类精度可提高4.633%。

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引用次数: 0

The geometry of infinitesimal mobility of closed-loop linkages 闭环连杆机构无穷小运动的几何性质

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2026-01-02 DOI: 10.1016/j.mechmachtheory.2025.106332

Nir Shvalb , Oded Medina

Classical mobility criteria such as the Chebyshev-Grübler-Kutzbach formula capture only first-order behaviour and may overlook geometric constraints of higher order. In this work we examine a large family of spatial closed-loop mechanisms that, despite satisfying the classical mobility count, are found to be rigid. Motivated by unexpectedly elegant geometric structure underlying this behaviour, we introduce the term hypo-paradoxical linkages to describe these mechanisms.

Our analysis combines screw theory with geometric considerations to identify when such higher-order restrictions arise and how they suppress motion. Representative examples are examined, and the effects of small design perturbations on the attainable workspace are quantified.

This geometric viewpoint also offers a fresh and intuitive interpretation of mobility of Bennet’s mechanism.

Overall, the results illustrate the limitations of traditional mobility criteria and point to a richer geometric foundation governing rigidity and motion in spatial linkages.

经典的迁移率标准，如切比舍夫-格拉伯勒-库茨巴赫公式，只捕捉一阶行为，而可能忽略高阶的几何约束。在这项工作中，我们研究了一个大的空间闭环机制家族，尽管满足经典的流动性计数，被发现是刚性的。由于这种行为背后出人意料的优雅几何结构，我们引入了术语“准悖论连杆”来描述这些机制。我们的分析将螺旋理论与几何考虑相结合，以确定何时出现这种高阶限制以及它们如何抑制运动。研究了代表性的例子，并量化了小的设计扰动对可实现的工作空间的影响。这种几何观点也为班纳特机械的机动性提供了一种新鲜而直观的解释。总的来说，结果说明了传统的流动性标准的局限性，并指出了一个更丰富的几何基础来控制空间联系的刚性和运动。

引用次数: 0

Design of jerk model and optimal time trajectory planning method based on smooth continuous oscillatory type curves 基于光滑连续振荡型曲线的振动模型设计及最优时间轨迹规划方法

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-12-31 DOI: 10.1016/j.mechmachtheory.2025.106342

Zhaojin Liu , Jiawei Li , Yuxiao Li , Shaoming Yao , Gang Wang

This paper presents a jerk-segmented trajectory planning method based on continuous oscillatory-type curves to address the requirements for smooth and rapid maneuvering of modern industrial robots. The method replaces the traditional step oscillatory curve with a continuous oscillatory curve as the foundational model for the jerk trajectory. Furthermore, the jerk-segment curve is extended to fully exploit the kinematic capabilities. Concurrently, an optimal time solution strategy for jerk-segmented trajectories, informed by effective order, is developed. This strategy enables flexible adjustment of the solution process based on the effective order. Additionally, we introduce a coordination factor to manage the relationship between the initial jerk and its kinematic constraints during continuous changes, thereby maximizing effective drivability and maintaining continuous control time for the jerk. A velocity synchronization strategy is proposed to coordinate multi-axis motion, further establishing the applicability of this method in industrial robotic systems. Numerical simulation analysis results indicate that this method exhibits superior performance in terms of time optimality, vibration generation, and suppression. The method's effectiveness has been field experimentally validated using a complex hybrid robot prototype.

针对现代工业机器人对平稳、快速运动的要求，提出了一种基于连续振荡型曲线的跳变分段轨迹规划方法。该方法用连续振荡曲线代替了传统的阶跃振荡曲线作为跳动轨迹的基础模型。此外，还扩展了抽动段曲线，以充分利用运动学能力。同时，提出了一种基于有效阶数的推力分段轨迹最优时间解策略。该策略允许根据有效顺序灵活调整解决方案流程。此外，我们引入了一个协调因子来管理连续变化过程中初始加速度与其运动学约束之间的关系，从而最大化有效驾驶性能并保持加速度的连续控制时间。提出了一种协调多轴运动的速度同步策略，进一步验证了该方法在工业机器人系统中的适用性。数值仿真分析结果表明，该方法在时间最优性、产生振动和抑制振动方面具有较好的性能。该方法的有效性已通过一个复杂的混合动力机器人样机进行了现场实验验证。

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引用次数: 0

Design and analysis of a Bricard-inspired dexterous hand based on generalized parallel mechanisms 基于广义并联机构的布里卡德式灵巧手设计与分析

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-12-30 DOI: 10.1016/j.mechmachtheory.2025.106340

Hongzeng Li , Bo Wang , Chunxu Tian , Dan Zhang

This paper proposes a novel generalized parallel dexterous hand with the aim of enhancing dexterity and stability. First, by using topological synthesis and number synthesis methods, an analysis is conducted on the degrees of freedom (DOF), number of loops, and link combinations of the topological structures of the dexterous hand. This analysis helps to identify effective non-isomorphic Contracted Graphs (CGs). Then, the configuration of a multi-mode deployable dexterous hand is designed based on the threefold-symmetric Bricard mechanism. A reconfigurable base is incorporated into this design to enhance the adaptability of the dexterous hand. Additionally, Lie group theory is employed to analyze the motion modes of the dexterous hand. Through simulation analysis, the grasping and motion performance under different motion modes are evaluated. Moreover, the forward and inverse kinematics of the dexterous hand are analyzed. Coordinate transformation methods are used to reduce the computational complexity. Finally, the workspace and motion force transmission performance of the dexterous hand are evaluated through simulation analysis.

提出了一种新型的广义平行灵巧手，以提高灵巧性和稳定性。首先，采用拓扑综合和数综合的方法，对灵巧手拓扑结构的自由度、环数和连杆组合进行了分析。这种分析有助于识别有效的非同构收缩图（cg）。然后，基于三对称Bricard机构，设计了多模态可展开灵巧手的构型。在设计中加入了可重构的底座，增强了灵巧手的适应性。此外，利用李群理论分析了灵巧手的运动模式。通过仿真分析，对不同运动模式下的抓取和运动性能进行了评价。并对灵巧手的正运动学和逆运动学进行了分析。采用坐标变换方法降低了计算复杂度。最后，通过仿真分析对灵巧手的工作空间和运动力传递性能进行了评价。

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引用次数: 0

Modeling of hysteresis curve and study of torsional rigidity and lost motion characteristics of the RV reducer RV减速器滞回曲线建模及扭转刚度和运动损失特性研究

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-12-30 DOI: 10.1016/j.mechmachtheory.2025.106335

Lixin Xu , Tianyu Zhao , Jianwei Geng , Yunqing Deng

Torsional rigidity and lost motion are critical performance indicators for evaluating the load capacity, motion stability, and positioning accuracy of the rotating vector (RV) reducer. This paper presents a dynamic modeling method for the RV reducer’s hysteresis curve and evaluates its torsional rigidity and lost motion based on the hysteresis curve. Firstly, the method provides the contact dynamic model of the RV reducer, including the influence of geometric errors in components. Secondly, the simulation control strategy for torque loading is developed based on the hysteresis curve test scheme. Besides, the validity of the calculation results is verified by experiment. Moreover, the effects of contact stiffness, bearing preload and clearance, and geometric errors of components on the hysteresis curve, as well as the torsional rigidity and lost motion, are discussed in detail. The results show that support bearing contact stiffness has the most significant influence on the torsional rigidity; radial clearance of the swivel arm bearing has a significant impact on the lost motion; and geometric errors of components will reduce the torsional rigidity and increase the lost motion.

扭转刚度和运动损失是评价旋转矢量减速器承载能力、运动稳定性和定位精度的关键性能指标。提出了RV减速器滞回曲线的动力学建模方法，并根据滞回曲线对RV减速器的扭转刚度和运动损失进行了评估。该方法首先建立了RV减速器的接触动力学模型，考虑了部件几何误差的影响；其次，基于滞回曲线试验方案，提出了转矩加载的仿真控制策略。并通过实验验证了计算结果的有效性。此外，还详细讨论了接触刚度、轴承预紧力和间隙、部件几何误差对滞回曲线以及扭转刚度和运动损失的影响。结果表明：支承轴承接触刚度对扭转刚度的影响最为显著；转臂轴承的径向游隙对运动损失有显著影响；构件的几何误差会降低扭转刚度，增加运动损失。

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引用次数: 0

A concept of the metamodel based on the dynamics analysis results of the eccentric crank-rocker mechanism 基于偏心曲柄摇杆机构动力学分析结果的元模型概念

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-12-29 DOI: 10.1016/j.mechmachtheory.2025.106333

Andrzej Urbaś, Jacek Stadnicki

This paper presents the concept of using the metamodel of the dynamics of the crank-rocker mechanism with eccentricity for its synthesis. The formalism of joint coordinates, homogeneous transformation matrices, and Lagrange equations are used to derive the mathematical model of the mechanism, which considers the flexibility of the drive and connecting rod. Using the mathematical model of the mechanism, the function of which is to compact the raw material using a rocker, the simulation of many dimensional variants of the mechanism is performed. Next, based on the results, a metamodel of the mechanism is proposed, with the design criterion being the maximal value of the rocker kinetic energy, which is adopted as a measure of the efficiency of raw material compaction. The metamodel is used in practice to determine the lengths of links of the mechanism that met the adopted design criteria. A comparison of options of the analysis of mechanism models with and without the flexibility of the drive or/and connecting rod is also presented.

本文提出了用偏心曲柄摇杆机构动力学元模型进行综合的概念。采用关节坐标、齐次变换矩阵和拉格朗日方程的形式建立了考虑传动和连杆柔性的机构数学模型。利用该机构的数学模型（其功能是利用摇杆对原材料进行压实），对该机构的多个维度变量进行了仿真。在此基础上，提出了该机构的元模型，设计准则为摇杆动能的最大值，并以此作为衡量原材料压实效率的指标。该元模型在实际中用于确定满足所采用的设计标准的机构的连杆长度。文中还比较了考虑和不考虑传动或连杆柔性的机构模型分析的选择。

引用次数: 0

Nonlinear topology optimization design of compliant mechanisms with tailored input/output stiffness 输入/输出刚度定制柔性机构的非线性拓扑优化设计

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-12-29 DOI: 10.1016/j.mechmachtheory.2025.106330

Yueyou Tang , Meng He , Zhen-Pei Wang , Liang Xia

Topology optimization of compliant mechanisms (CMs) typically seeks to maximize input stiffness while minimizing output stiffness to achieve optimal geometric advantage (GA). However, simultaneously tailoring input and output stiffness inherently conflicts with these objectives, a challenge that is exacerbated under nonlinear conditions. To address this, we propose a nested optimization framework incorporating geometric and material nonlinearities, which decouples the problem into two levels: the outer loop maximizes GA, while the inner loop enables precise input/output stiffness customization. An adaptive volume control strategy is further introduced to suppress hinge-like features and improve material efficiency. Numerical examples demonstrate that the method yields hinge-free topologies with input and output stiffness closely matching the targets. Finally, a series of CMs with varying stiffness ratios were designed and fabricated. Experimental results confirm the effectiveness of proposed method in tailoring input/output stiffness, while verifying the output-end resistance to external excitations and the required input actuation force. The method is applicable to mechanisms with specific performance demands, such as low-actuation, high-output-stability robotic grippers and medical instruments with both high input and output stability.

柔性机构（CMs）的拓扑优化通常寻求最大的输入刚度和最小的输出刚度，以实现最佳的几何优势（GA）。然而，同时调整输入和输出刚度本身就与这些目标相冲突，在非线性条件下，这是一个更大的挑战。为了解决这个问题，我们提出了一个包含几何和材料非线性的嵌套优化框架，该框架将问题解耦为两个层次：外环最大化遗传算法，而内环实现精确的输入/输出刚度定制。进一步引入自适应体积控制策略来抑制铰链特征并提高材料效率。数值算例表明，该方法得到的无铰拓扑结构输入和输出刚度与目标结构高度匹配。最后，设计并制作了一系列不同刚度比的复合材料。实验结果证实了该方法在调整输入/输出刚度方面的有效性，同时验证了输出端对外部激励的阻力和所需的输入作动力。该方法适用于具有特定性能要求的机构，如低驱动、高输出稳定性的机器人抓手和高输入输出稳定性的医疗器械。

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引用次数: 0

Integrated design of scale-structure-drive for high-speed and heavy-load dual-robot pose adjustment system 高速重载双机器人位姿调整系统的尺度-结构驱动一体化设计

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-12-29 DOI: 10.1016/j.mechmachtheory.2025.106336

Zecun Guo , Chuanying Wang , Dong Wang , Luwei Liu , Ziyi Ding , Kaixuan Chen , Tao Sun

The sheet metal pose adjustment equipment for stamping production lines faces three challenges: high-speed, heavy-load, and double operating modes. This paper proposes a new type of dual-robot system to meet the application requirements of sheet metal pose adjustment. The pose adjustment mechanism innovatively decouples the load inertia force from gravity through the combination of ball transfer units and a planar parallel mechanism. The pose adjustment system can complete the pose adjustment operation of a 3.2-ton load within 0.45 s. A dual-robot design method is proposed, which takes into account the elastic dynamic behavior and reliability of key structural components. The external layer of this method optimizes the scale-structure-drive parameters of the planar mechanism, while the internal layer optimizes the layout parameters of the ball transfer units for the parameter combinations determined by the external layer, achieving the integrated design of the dual-robot system. Through this optimization, the in-plane linear stiffness of the dual-robot positioning system is increased by 17.6 %, the driving force is reduced by 12.4 %, and the natural frequency is improved by 16.3 %.

冲压生产线钣金位姿调整设备面临高速、重载、双工况三大挑战。针对钣金位姿调整的应用需求，提出了一种新型的双机器人系统。姿态调整机构创新地将滚珠传递单元与平面并联机构相结合，将载荷惯性力与重力解耦。位姿调整系统可在0.45 s内完成3.2吨负载的位姿调整操作。提出了一种考虑关键结构部件弹性动力性能和可靠性的双机器人设计方法。该方法的外层对平面机构的尺度-结构-驱动参数进行优化，内层对由外层确定的参数组合进行球传递单元布局参数的优化，实现了双机器人系统的一体化设计。优化后的双机器人定位系统平面内线性刚度提高了17.6%，驱动力降低了12.4%，固有频率提高了16.3%。

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引用次数: 0