Mechanism and Machine Theory最新文献_第9页

Modelling gear mesh stiffness including axial effects: Approximate approach 齿轮啮合刚度建模包括轴向效应：近似方法

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-10-22 DOI: 10.1016/j.mechmachtheory.2025.106221

Francisco H.J. Ricardo , João D.M. Marafona , Pedro M.T. Marques

Recently, with the advancement in technology, gear mesh stiffness has been a central topic in gear design optimisation and gear dynamics. Consequently, some approximate models for spur and helical gears have been developed due to their low computational cost. However, these models disregarded the axial component of the gear mesh stiffness. To address this issue, a new approximate expression is developed accounting for the axial effect, having as starting point a previously developed approximate expression that considers only the transverse component. The new expression is validated for a random sample representative of all possible gears within a wide range of geometric parameters. The new approximate model for helical gears, based on the development of an expression for the single tooth pair slice structural mesh stiffness, revealed to be fast and accurate, confirming the applicability of the model and proving that it is capable of replacing the more time consuming methods for the same applications. Additionally, a single equation relying on a single constant aiming to convert the transverse into normal stiffness is presented.

近年来，随着技术的进步，齿轮啮合刚度已成为齿轮设计优化和齿轮动力学的中心课题。因此，由于正齿轮和斜齿轮的计算成本较低，人们开发了一些近似模型。然而，这些模型忽略了齿轮啮合刚度的轴向分量。为了解决这个问题，开发了一个新的近似表达式，考虑轴向效应，以先前开发的近似表达式为起点，只考虑横向分量。新的表达式验证了一个随机样本代表所有可能的齿轮在广泛的几何参数范围内。在建立单齿对片结构啮合刚度表达式的基础上，建立的斜齿轮近似模型快速、准确，验证了该模型的适用性，并证明了该模型能够代替耗时较长的方法实现相同的应用。此外，还提出了一个依赖于单一常数的单一方程，旨在将横向刚度转换为法向刚度。

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引用次数: 0

On the lumped parameter modeling of worm gear mechanisms: Experimental validation and insights 蜗轮机构集总参数建模：实验验证与启示

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-10-22 DOI: 10.1016/j.mechmachtheory.2025.106266

Giulia Cristofori, Mattia Battarra, Emiliano Mucchi

A non-linear 8-DOF model capable of capturing the fundamentals of the worm gear dynamics has been developed. The model incorporates external excitations, non-linear time-varying meshing stiffness, and components related to friction phenomena. This study is dedicated to a thorough exposition of the lumped parameter model, accompanied by a comprehensive examination of its equations and an analysis of the impact of diverse contributions. The procedure employed to determine the meshing stiffness is further investigated using a finite element methodology, as it is a crucial input for the dynamic model. Furthermore, a comprehensive description of the experimental campaign conducted to validate the model is presented, enabling an in-depth analysis of the impact of speed and torque on the overall dynamics of worm gear mechanisms. In order to assess the capability of the model to accurately capture the effects of these two parameters, a comparison is made between the numerical results, specifically the bearing forces and transmission errors, and the experimental data. These comparisons facilitate the validation of the model.

一个非线性的8-DOF模型能够捕捉基本的蜗轮动力学已开发。该模型考虑了外部激励、非线性时变网格刚度和与摩擦现象相关的分量。本研究致力于对集总参数模型进行全面的阐述，同时对其方程进行全面的检查，并分析各种贡献的影响。用于确定网格刚度的程序使用有限元方法进行了进一步研究，因为它是动态模型的关键输入。此外，对验证模型的实验活动进行了全面的描述，从而能够深入分析速度和扭矩对蜗轮机构整体动力学的影响。为了评估模型准确捕捉这两个参数影响的能力，将数值结果（特别是轴承力和传动误差）与实验数据进行了比较。这些比较有助于模型的验证。

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引用次数: 0

A novel time-optimal feedrate planning method for robots with contour error constraints 一种具有轮廓误差约束的机器人时间最优进给速度规划方法

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-10-21 DOI: 10.1016/j.mechmachtheory.2025.106227

Qi Qi, Jixiang Yang, Wenhao Li, Han Ding

Existing time-optimal feedrate planning methods for robots typically consider the robot's drive capability limitations, while neglect the limitation of the robot motion accuracy especially the contour accuracy. To address this issue, this paper proposes a novel time-optimal feedrate planning method for robots with contour error constraints. First, a joint tracking error prediction model for the robot considering the control loop and the robot end load is established, and a contour error constraint model for feedrate planning is proposed. Secondly, an improved feedrate squared B-spline is used to transform the feedrate planning problem into a linear optimization problem represented by control points. For jerk constraints, joint torque constraints and contour error constraints that cannot be directly converted into linear constraints, a scaling estimation method is proposed to linearize all nonlinear constraint equations in feedrate planning. Thirdly, a two-step linear programming (LP) method is proposed to solve the time-optimal feedrate planning considering contour error constraints. Comparative experiments conducted on a robot demonstrate that the proposed method can effectively improve the robot's motion efficiency while satisfying the contour error constraints.

现有的机器人时间最优进给规划方法通常考虑机器人的驱动能力限制，而忽略了机器人运动精度特别是轮廓精度的限制。针对这一问题，提出了一种具有轮廓误差约束的机器人时间最优进给速度规划方法。首先，建立了考虑控制环和末端载荷的机器人联合跟踪误差预测模型，并提出了用于进给速度规划的轮廓误差约束模型；其次，利用改进的进给速度平方b样条将进给速度规划问题转化为由控制点表示的线性优化问题；针对不能直接转化为线性约束的抽动约束、关节力矩约束和轮廓误差约束，提出了一种尺度估计方法，将进给速度规划中的所有非线性约束方程线性化。第三，提出了一种考虑轮廓误差约束的两步线性规划方法来求解时间最优进给速度规划问题。在机器人上进行的对比实验表明，该方法在满足轮廓误差约束的情况下，有效地提高了机器人的运动效率。

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引用次数: 0

Performance Influences and selection criteria for actuated joints on redundant parallel mechanisms—by two novel design examples 冗余并联机构驱动节点的性能影响及选择准则——以两个新颖的设计实例为例

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-10-21 DOI: 10.1016/j.mechmachtheory.2025.106263

Ju LI, Zhongqiu DU, Junjie SHE, Huiping SHEN

The selection of actuated joints in the limbs of redundant parallel mechanisms (RPMs) is a critical design challenge, as the number of limbs typically exceeds the degree of freedom (DOF). Despite its importance, this issue has received limited attention in the literature. This paper addresses the gap by proposing two examples of 2-DOF RPMs with redundant limbs, analyzing the impact of different actuated joints on the performance of RPMs. One example is a spatial two-translation RPM, and the other is a planar one-translation and one-rotation RPM. The influence of various actuated joints on the kinematic, stiffness, and dynamic performance of these RPMs is thoroughly examined under two actuated joint schemes. A comparative analysis reveals that each scheme has distinct advantages and disadvantages, making them suitable for different applications. Based on this analysis, the paper proposes application scenario requirement-based selection criteria for actuated joints of RPMs. This work provides a clear procedure for actuated joint selection and offers valuable insights into the design and application of RPMs.

冗余并联机构分支的驱动关节选择是一个关键的设计挑战，因为分支的数量通常超过了自由度。尽管它很重要，但这个问题在文献中得到的关注有限。本文通过给出两个具有冗余分支的2-DOF rpm实例，分析了不同驱动关节对rpm性能的影响，从而解决了这一问题。一个例子是空间两平移RPM，另一个例子是平面一平移一旋转RPM。在两种驱动关节方案下，深入研究了各种驱动关节对这些rpm的运动学、刚度和动态性能的影响。对比分析表明，每种方案都有其独特的优点和缺点，适合不同的应用。在此基础上，提出了基于应用场景需求的rpm驱动关节选择准则。这项工作为驱动关节的选择提供了一个清晰的程序，并为rpm的设计和应用提供了有价值的见解。

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引用次数: 0

A fault diagnosis method for bearings based on multiscale graph convolutional network under non-stationary speed conditions 非平稳转速条件下基于多尺度图卷积网络的轴承故障诊断方法

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-10-21 DOI: 10.1016/j.mechmachtheory.2025.106267

Xueyi Li , Guangsheng Ran , Shuquan Xiao , Kaiyu Su , Qi Li , Tianyang Wang , Zhaoye Qin , Fulei Chu

Current research on intelligent fault diagnosis primarily focuses on constant speed conditions, with less attention given to time-varying speed scenarios. Additionally, relying on single-sensor data limits the robustness and adaptability of intelligent fault diagnosis methods. Therefore, this paper proposes a Multi-Scale Elastic Spatial Convolutional Deep Graph Convolutional Network (ESC-DGCN) Cascaded Fusion Framework for multi-sensor fault diagnosis under time-varying speed conditions. The proposed elastic spatial convolution mechanism adapts to input signals of varying lengths and effectively extracts time-varying speed signal features. The multi-scale graph convolutional network aggregates information from multiple sensor nodes, enhancing feature representation. A cascaded fusion strategy is introduced to efficiently integrate fault features with node features, improving diagnostic performance. Experimental results show that the proposed framework achieves an average diagnostic accuracy of 99.28 % on the Northeast Forestry University dataset and 99 % on two public benchmark datasets, outperforming the best baseline method by 0.72 %, 2.11 %, and 1.3 %, respectively. Experimental results based on datasets from Northeast Forestry University and publicly available datasets validate the effectiveness of the proposed method.

目前对智能故障诊断的研究主要集中在匀速工况下，对时变工况关注较少。此外，依赖单一传感器数据限制了智能故障诊断方法的鲁棒性和适应性。为此，提出了一种多尺度弹性空间卷积深度图卷积网络（ESC-DGCN）级联融合框架，用于时变速度条件下的多传感器故障诊断。所提出的弹性空间卷积机制能够适应不同长度的输入信号，有效提取时变速度信号特征。多尺度图卷积网络聚合了多个传感器节点的信息，增强了特征表示。采用级联融合策略，将故障特征与节点特征有效融合，提高了诊断性能。实验结果表明，该框架在东北林业大学数据集上的平均诊断准确率为99.28%，在两个公共基准数据集上的平均诊断准确率为99%，分别比最佳基线方法高0.72%、2.11%和1.3%。基于东北林业大学数据集和公开数据集的实验结果验证了该方法的有效性。

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引用次数: 0

Configuration design and redundancy optimization of a novel kinematically redundant parallel external fixator for interference avoidance in foot and ankle deformity correction 一种新型运动冗余并联外固定架的结构设计与冗余优化，用于足、踝畸形矫治中避免干扰

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-10-18 DOI: 10.1016/j.mechmachtheory.2025.106265

Jie Ju , Jianfeng Li , Tuxian Ye , Qianhui Ma , Mingjie Dong , Shiping Zuo , Wei-Hsin Liao

During foot and ankle deformity correction via external fixators, successful implementation of the preplanned optimal correction strategy is crucial for achieving acceptable correction outcomes. However, interference phenomena can interrupt the correction process. Owing to the inherent non-redundant mechanism properties of existing external fixators, current interference avoidance methods inevitably necessitate adjustments of the pre-determined assembly relation and/or equally-spaced correction trajectories, thereby hindering the implementability of the optimal correction strategy. To address this issue, this paper introduces the concept of kinematic redundancy in external fixator design, and a novel 2(SPS-P-SPS)-SPR kinematically redundant external fixator with configuration optimization capabilities is proposed. Subsequently, based on the algebraic solution for forward kinematics while combining the cost functions for interference avoidance tasks, the inverse kinematics of the proposed external fixator is resolved using the gradient projection method with closed-loop feedback. Clinical case simulations demonstrate the effectiveness of the external fixator in avoiding multiple interference problems while maintaining the optimal correction strategy. Comparative analyses further reveal considerable improvements in the tracking accuracy of the correction trajectory compared with the conventional velocity-level method with open-loop solutions.

在通过外固定架进行足部和踝关节畸形矫正时，成功实施预先规划的最佳矫正策略对于获得可接受的矫正结果至关重要。然而，干扰现象会中断校正过程。由于现有外固定器固有的非冗余机构特性，当前的干涉避免方法不可避免地需要调整预先确定的装配关系和/或等间距校正轨迹，从而阻碍了最优校正策略的实现。为了解决这一问题，本文在外固定架设计中引入了运动冗余的概念，提出了一种具有构型优化能力的2(SPS-P-SPS)-SPR运动冗余外固定架。随后，在求解正运动学代数解的基础上，结合避免干扰任务的代价函数，采用带闭环反馈的梯度投影法求解该外固定器的运动学逆解。临床案例模拟证明了外固定架在避免多重干扰问题的同时保持最佳矫正策略的有效性。对比分析进一步表明，与传统的开环速度级方法相比，修正轨迹的跟踪精度有了很大提高。

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引用次数: 0

Research on a novel multiple cable-nets swing capture mechanism and its space gripper design 一种新型多索网摆动捕获机构及其空间夹持器设计研究

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-10-18 DOI: 10.1016/j.mechmachtheory.2025.106264

Yuan Jiang , Yongsheng Zhao , Yi Luo , Qianqian Gu , Xiaohan Liu , Meng Han , Bo Han

Space capture is a key technology for deep space exploration, serving missions such as orbital debris removal and asteroid sampling. Target objects are typically non-cooperative and operate in environments devoid of gravity and fluid resistance, posing significant challenges to effective capture. Cables, known for their compliance and excellent mechanical properties, have been used in space capture tasks. However, few studies have achieved both reliable control and the use of cables as end-effectors. To address this gap, this paper proposes a novel mechanism—the multiple cable-nets swing capture mechanism (MCNS-CM)—which enables compliant capture of targets by synchronously swinging multiple intersecting cable-nets to narrow the capture space. MCNS-CM employs cables as the end-effector structure, offering low-impact, high-compliance, and self-adaptive contact behavior. The mathematical principles, kinematic and mechanical models of MCNS-CM are presented. Two proof-of-concept prototypes were fabricated, and a series of capture experiments were conducted, demonstrating the feasibility of MCNS-CM in space capture and related applications. This work provides new insights and a theoretical foundation for the advancement of future space capture technologies.

空间捕获是深空探测的一项关键技术，服务于轨道碎片清除和小行星采样等任务。目标物体通常是非合作的，并且在没有重力和流体阻力的环境中运行，这对有效捕获构成了重大挑战。电缆以其顺应性和优异的机械性能而闻名，已用于空间捕获任务。然而，很少有研究既能实现可靠的控制，又能使用电缆作为末端执行器。为了解决这一差距，本文提出了一种新的机制——多缆网摆动捕获机制（MCNS-CM），该机制通过同步摆动多个相交的缆网来缩小捕获空间，从而实现目标的顺从捕获。MCNS-CM采用电缆作为末端执行器结构，提供低冲击，高顺应性和自适应接触行为。介绍了MCNS-CM的数学原理、运动学模型和力学模型。制作了两个概念验证原型，并进行了一系列捕获实验，证明了MCNS-CM在空间捕获和相关应用中的可行性。这项工作为未来空间捕获技术的发展提供了新的见解和理论基础。

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引用次数: 0

Multi-configuration recognition of a 3-RSR parallel mechanism with zero-torsion characteristics based on screw algebra and high-order kinematics 基于螺旋代数和高阶运动学的零扭力3-RSR并联机构多构型识别

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-10-18 DOI: 10.1016/j.mechmachtheory.2025.106249

Haolin Zhang, Lizi Deng, Zhao Tang, Jian S. Dai

In this paper, a comprehensive high-order kinematic analysis of a geometrically symmetric 3-RSR parallel mechanism is conducted based on screw algebra. A screw-based modeling framework is first established to represent the pose and evaluate the mobility under zero-torsion characteristics, revealing the mechanism's intrinsic 2R1T motion pattern. The bifurcation configurations of the 3-RSR mechanism under singularity are then identified, deriving five distinct motion modes: decoupled limb-swinging, parallel translation, two interfering rotational modes, and axis rotation. Eleven bifurcated motion branches are subsequently derived through high-order velocity constraints and symmetry extension. In particular, a complete symmetry-based configuration space is constructed for the first time, which enables systematic recognition and classification of multimodal motion. Moreover, the feasibility of connectivity among motion branches is verified through constraint screw evolution. These findings not only deepen the understanding of singularity-induced bifurcations in reconfigurable parallel mechanisms, but also establish the constraint principles that govern configuration transitions of reconfigurable parallel mechanisms under singular configurations.

本文基于螺旋代数对几何对称3-RSR并联机构进行了全面的高阶运动学分析。首先建立了基于螺旋的姿态建模框架，并对机构零扭转特性下的机动性进行了评估，揭示了机构固有的2R1T运动模式。在此基础上，对3-RSR机构在奇异点下的分岔构型进行了辨识，推导出解耦摆动臂、并联平移、双干涉旋转和轴向旋转五种不同的运动模式。通过高阶速度约束和对称扩展导出了11个运动分支。特别是首次构建了一个完整的基于对称的构型空间，实现了对多模态运动的系统识别和分类。通过约束螺杆演化验证了运动分支间连通性的可行性。这些发现不仅加深了对可重构并联机构奇点分岔的认识，而且建立了奇异构型下可重构并联机构构型转移的约束原则。

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引用次数: 0

Design and analysis of a new parallel mechanism with foldable moving platforms—coupled with its conceptual design in multi-pose tracking of PV modules 一种新型可折叠移动平台并联机构的设计与分析——结合光伏组件多姿态跟踪的概念设计

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-10-17 DOI: 10.1016/j.mechmachtheory.2025.106261

Huiping Shen, Xingyu She, Zhongqiu Du, Pengda Ye, Ju Li

In the work, a new concept of parallel mechanism(PM) with two foldable moving platforms, i.e., foldable PM, is proposed. A 4-DOF 2T1R foldable PM consists of two sub-PMs connected by one shared hybrid limb is designed and analyzed, each sub-PM of which possess 2T1R output motion. Only through control of the actuated joints of the foldable PM, without changing topology of the foldable PM itself, its two sub-moving platforms can reach respective 2T1R motion output. First, topological characteristics of the foldable PM are analyzed, including position and orientation characteristics (POC), degrees of freedom (DOF) etc. Second, symbolic forward and inverse position solutions, workspace and singular analysis are performed. Third, the dynamic equations and actuated force curves are established through the virtual work principle. Fourth, dimensional optimization is conducted with the maximum attitude angle as the objective function. Finally, the conceptual design of the foldable PM used for multi-pose tracking of photovoltaic (PV) modules for efficient energy absorption is elaborated. This work expands the concept, design, and application scope of reconfigurable or multi-mode PMs.

本文提出了一种具有两个可折叠移动平台的并联机构的新概念，即可折叠并联机构。设计并分析了一种4自由度2T1R可折叠永磁机构，该机构由两个子永磁机构组成，每个子永磁机构具有2T1R输出运动。仅通过控制可折叠永磁机构的驱动关节，在不改变可折叠永磁机构本身拓扑结构的情况下，其两个子运动平台即可达到各自的2T1R运动输出。首先，分析了可折叠PM的拓扑特性，包括位姿特性（POC）、自由度（DOF）等。其次，进行了符号正、逆位置解、工作空间和奇异性分析。第三，利用虚功原理建立了动力方程和驱动力曲线。第四，以最大姿态角为目标函数进行量纲优化。最后，阐述了用于光伏组件多姿态跟踪的可折叠PM的概念设计，以实现高效的能量吸收。这项工作扩展了可重构或多模式pm的概念、设计和应用范围。

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引用次数: 0

Inverse kinematics framework for a 2R-3R-2R upper-limb exoskeleton using vector method 基于矢量法的2R-3R-2R上肢外骨骼逆运动学框架

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-10-17 DOI: 10.1016/j.mechmachtheory.2025.106234

Jiajia Wang , Shuo Pei , Junlong Guo , Chuan Zhou , Lining Sun , Hejiang Shang , Chenghua Tian , Yufeng Yao

Traditional inverse kinematics (IK) methods have been primarily developed for industrial robots and focus solely on end-effector poses. However, they cannot be applied to exoskeletons owing to differences in the configuration design and the requirement for kinematic compatibility between humans and exoskeletons. The 2R-3R-2R upper-limb exoskeleton supports shoulder girdle motion and achieves a full range of upper-limb movements without causing discomfort to the users. This study proposes an IK framework for 2R-3R-2R upper-limb exoskeletons to map the vectors of the upper limb segments to the joint space using the vector method. Moreover, the framework can accommodate four task description methods, while maintaining multiple IK solutions. The proposed framework was evaluated against recently published methods, and its effectiveness was further validated through simulations. The computational times for the four task description methods were 0.033 ms, 0.43 ms, 0.76 ms, and 7.1 ms, respectively. The maximum Euler angle and maximum position error of the end-effector for the four task description methods were captured within

6 \times 1 0^{- 12}

rad and

1.2 \times 1 0^{- 9} mm

, respectively.

传统的逆运动学（IK）方法主要是为工业机器人开发的，并且只关注末端执行器的姿势。然而，由于人体和外骨骼在结构设计和运动兼容性要求上的差异，它们不能应用于外骨骼。2R-3R-2R上肢外骨骼支持肩带运动，实现全方位的上肢运动，而不会给使用者带来不适。本研究提出了一种用于2R-3R-2R上肢外骨骼的IK框架，使用向量方法将上肢节段的向量映射到关节空间。此外，该框架可以容纳四种任务描述方法，同时保持多个IK解决方案。将该框架与最近发表的方法进行了比较，并通过仿真进一步验证了其有效性。四种任务描述方法的计算时间分别为0.033 ms、0.43 ms、0.76 ms和7.1 ms。四种任务描述方法的末端执行器最大欧拉角和最大位置误差分别在6×10−12 rad和1.2×10−9mm范围内获得。

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引用次数: 0