Mechanism and Machine Theory最新文献_第6页

Closed-form forward kinematics, singularity, dexterity and workspace analyses of a special class of 3-RRR spherical parallel mechanisms 一类特殊的3-RRR球面并联机构的闭式正运动学、奇异性、灵巧性和工作空间分析

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-12-04 DOI: 10.1016/j.mechmachtheory.2025.106288

Shuai Zhang , Wei Li , Huayan Pu , Rui Chen , Jun He , Jun Luo

3-RRR spherical parallel mechanisms (SPMs) are capable of producing three-DOF spherical motion, which can find applications in various fields. This paper investigates the kinematics and workspace performance of a particular class of 3-RRR SPMs, characterized by coaxial input-joint axes, coplanar distal-joint axes, and six orthogonal links. First, two novel formulations are proposed for the forward kinematics (FK) of this robot class, both resulting in linear univariate polynomials that significantly streamline the FK formulation and reduce the computational complexity. Moreover, this robot class exhibits minimal and physically interpretable singularity loci in both the orientation workspace and the input joint space, greatly facilitating singularity avoidance and path planning. Furthermore, local and global dexterity indices are employed to analyze the mechanism’s performance, from which the architectural parameters yielding optimal dexterity are identified. Finally, the robot class demonstrates a considerably large tilt-torsion orientation workspace when the architectural parameters and link shapes are appropriately selected, allowing for infinite torsional motion when pointed within almost a hemisphere. The foregoing features make the robot class potentially promising in a wide range of applications.

3-RRR球面并联机构（SPMs）具有三自由度球面运动的能力，在各个领域都有广泛的应用。本文研究了一类具有同轴输入关节轴、共面远关节轴和六个正交连杆的3-RRR SPMs的运动学和工作空间性能。首先，对该类机器人的正运动学（FK）提出了两种新颖的公式，均得到线性单变量多项式，大大简化了FK的公式，降低了计算复杂度。此外，该类机器人在姿态工作空间和输入关节空间中都具有最小且物理可解释的奇异轨迹，极大地促进了奇异避免和路径规划。此外，采用局部和全局灵巧度指标分析机构的性能，从而确定最优灵巧度的结构参数。最后，当适当选择结构参数和连杆形状时，机器人类展示了相当大的倾斜-扭转方向工作空间，当指向几乎一个半球时，允许无限扭转运动。上述特点使得该类机器人具有广泛的应用前景。

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引用次数: 0

Optimal control approach for trajectory determination to suppress residual frame vibrations of delta robots in pick and place tasks delta机器人拾取任务中抑制机架残余振动的轨迹确定最优控制方法

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-12-02 DOI: 10.1016/j.mechmachtheory.2025.106302

Nils Brückmann , Christian Mirz , Mathias Hüsing , Yukio Takeda , Burkhard Corves

This paper proposes an optimal control approach to reduce frame vibrations in robotic pick and place tasks, caused by rapid acceleration and deceleration of the robot. The objective of the proposed optimal control approach is to determine time-optimal trajectories that cancel out residual frame vibrations after trajectory execution. The control problem is defined for a delta robot but can be adapted to any type of robot used for pick and place tasks. To solve the optimal control problem numerically, it is transformed into a nonlinear programming problem using the Legendre-Gauss-Lobatto collocation method. To validate the approach, experiments are conducted to compare the residual frame vibrations of optimized trajectories with typical pick and place trajectories. The novelty of the paper is the vibration reduction with an optimization-based approach on a complex multi-degree-of-freedom robot system whose dynamic parameters are identified with experimental data. In addition, a mathematical description of all constraints required for a robotic pick and place task is proposed for the optimization.

本文提出了一种最优控制方法，以减少机器人在拾取和放置任务中由于机器人的快速加减速而引起的机架振动。所提出的最优控制方法的目标是确定时间最优的轨迹，以消除轨迹执行后残留的框架振动。控制问题是为delta机器人定义的，但可以适用于任何类型的机器人用于拾取和放置任务。采用legende - gaas - lobatto配置法将最优控制问题转化为非线性规划问题，实现了最优控制问题的数值求解。为了验证该方法，通过实验将优化后的轨迹与典型的拾取轨迹的残余框架振动进行了比较。本文的新颖之处在于利用实验数据识别复杂多自由度机器人系统的动态参数，并采用基于优化的方法进行减振。此外，提出了机器人拾取和放置任务所需的所有约束的数学描述，以进行优化。

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引用次数: 0

Enhanced obstacle-crossing capability of redundantly actuated wheel-legged robot through dynamic stability and actuation pattern analyses 通过对冗余驱动轮腿机器人的动态稳定性和驱动模式分析，增强了其越障能力

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-12-02 DOI: 10.1016/j.mechmachtheory.2025.106305

Bike Zhu, Jun He, Feng Gao

The exploration of challenging terrains requires robotic systems with advanced mobility and adaptability. However, maintaining stability and maneuverability while traversing obstacles remains a significant challenge for such systems. Redundantly actuated wheel-legged rovers present a promising solution by introducing additional degrees of actuation, enabling more optimized motion strategies and enhanced overall performance. This paper focuses on enhancing the obstacle-crossing capability of these systems by analyzing the dynamic stability criteria and actuation patterns, using the TAWL rover as demonstration. Firstly, the dynamic models of the TAWL rover’s individual leg and the whole body are established, and the dynamic stability criteria are introduced. Secondly, the actuation patterns of the redundant system are analyzed to identify feasible actuation patterns and evaluate associated energy consumption. Thirdly, enhanced obstacle-crossing strategies are proposed, consisting of two components: increasing the rover’s maximum obstacle-crossing height and improving its stability when traversing specific obstacles. Finally, the proposed method is validated on the TAWL rover. The results demonstrate that the proposed method enables the rover to achieve maximum obstacle-crossing height and exhibit superior stability margin while traversing obstacles.

探索具有挑战性的地形需要具有先进机动性和适应性的机器人系统。然而，在穿越障碍物时保持稳定性和机动性仍然是这种系统面临的重大挑战。冗余驱动轮腿漫游者通过引入额外的驱动度，实现更优化的运动策略和增强的整体性能，提供了一个有前途的解决方案。本文以TAWL探测车为例，分析了该系统的动态稳定性准则和驱动模式，重点研究了如何提高该系统的越障能力。首先，建立了TAWL漫游车单腿和整体的动力学模型，并引入了其动态稳定性准则；其次，对冗余系统的驱动模式进行了分析，确定了可行的驱动模式，并对相关能耗进行了评估。第三，提出了增强的越障策略，包括提高漫游车的最大越障高度和提高漫游车在穿越特定障碍物时的稳定性两部分。最后，在TAWL漫游车上对该方法进行了验证。结果表明，该方法能使漫游车在越障过程中获得最大越障高度和优越的稳定裕度。

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引用次数: 0

Knowledge-enhanced optimization of a mobile parallel robot considering topological structure and dimensions 考虑拓扑结构和尺寸的移动并联机器人的知识增强优化

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-12-01 DOI: 10.1016/j.mechmachtheory.2025.106303

Binbin Lian , Qiqi Dong , Xinming Huo , Zihou Yuan , Qi Li , Tao Sun

Mobile parallel robots, formed by mounting parallel mechanisms on AGVs, combine merits of both automatic transporting and high-precision operation of large-scale parts. Optimal design of mobile parallel robots faces two key challenges: (1) co-optimizing topology of AGV frame and dimension of parallel module, (2) difficulty in embedding domain knowledge to the conventional “black-box” optimization. To address these, we propose a knowledge-enhanced optimization framework. Kinematic, stiffness, and mass models of parallel module, as well as surrogate model of AGV frame are established. A knowledge base is built by explicit knowledge from engineering and knowledge extraction through cluster analysis. Hard and soft constraints are defined, in which soft constraints are embedded to objective. Initial population of optimization searching is determined by preference-domain cluster, and a knowledge-guided multi-objective algorithm is developed. Comparative study to the optimization without knowledge injection show that Pareto front solutions of our method concentrate densely in designer-preferred regions. It achieves 36.45 % higher preference-aligned performance and shows accelerated convergence with stabilized HV progression curves. The framework effectively addresses co-optimization challenges by knowledge fusion and preference guidance.

移动并联机器人是将并联机构安装在agv上形成的，兼具大型零件自动输送和高精度操作的优点。移动并联机器人的优化设计面临两个关键挑战：(1)AGV框架拓扑与并联模块尺寸的协同优化；(2)传统的“黑箱”优化难以嵌入领域知识。为了解决这些问题，我们提出了一个知识增强的优化框架。建立了并联模块的运动学模型、刚度模型和质量模型以及AGV车架的代理模型。从工程中获取显性知识，通过聚类分析提取知识，构建知识库。定义了硬约束和软约束，其中软约束嵌入到目标中。利用偏好域聚类确定优化搜索的初始种群，提出了一种知识引导的多目标算法。与无知识注入优化的对比研究表明，该方法的Pareto前解密集地集中在设计人员偏好的区域。在稳定的HV级数曲线下，该算法的优先对准性能提高了36.45%，收敛速度加快。该框架通过知识融合和偏好引导有效地解决了协同优化挑战。

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引用次数: 0

Design and reinforcement learning-based locomotion gait planning for an 8-bar single-loop transformable robot 基于强化学习的8杆单回路可变形机器人运动步态规划设计

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-11-30 DOI: 10.1016/j.mechmachtheory.2025.106304

Meng Zhao, Zoulang Qin, Wenxuan Cheng, Ruiming Li, Hui Yang, Yezhuo Li, Jianxu Wu

Transformable robots with closed-chain mechanisms that exhibit underactuated and nonlinear dynamics pose a formidable challenge in gait planning. This paper introduces a two-stage reinforcement learning (RL) framework that bypasses the need for accurate system modeling to autonomously discover and refine locomotion gaits. We apply this method to an 8-bar single-loop transformable robot, whose kinematic analysis confirms its reconfigurability and variable degrees of freedom (DoF) nature. Our approach successfully generating two distinct and functional gaits: a stable peristaltic gait and a dynamic rolling gait that strategically leverages singular configurations. Extensive experiments on a physical prototype validate the gaits’ effectiveness across various terrains, with the robot achieving displacements of up to 870 mm at speeds of 8.7 mm/s. This work demonstrates a learning-based paradigm for planning complex locomotion in reconfigurable robotic systems.

具有闭链机构的变形机器人表现出欠驱动和非线性动力学特性，对步态规划提出了严峻的挑战。本文介绍了一种两阶段强化学习（RL）框架，该框架不需要精确的系统建模来自主发现和改进运动步态。将该方法应用于一个8杆单回路可变形机器人，运动学分析证实了该机器人的可重构性和可变自由度。我们的方法成功地生成了两种不同的功能性步态：稳定的蠕动步态和动态的滚动步态。在物理样机上进行的大量实验验证了步态在各种地形上的有效性，机器人在8.7毫米/秒的速度下实现了高达870毫米的位移。这项工作展示了一种基于学习的范式，用于规划可重构机器人系统中的复杂运动。

引用次数: 0

Flank modification and meshing analysis of harmonic drives with controlled backlash 可控间隙谐波传动的侧面修正与啮合分析

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-11-27 DOI: 10.1016/j.mechmachtheory.2025.106296

Xinzi Li, Chaosheng Song, Hailan Song

To address the challenge of correlating tooth flank modification design with meshing performance in harmonic drives, this study proposes an optimization method for meshing characteristics based on the control of meshing backlash. First, geometric models of the flexspline (produced by hobbing) and circular spline (produced by power skiving) are established. Subsequently, a computational procedure for determining meshing backlash in harmonic drives, incorporating tooth flank modification, is developed based on kinematic modeling. Finite element analysis is then employed to investigate the relationship between tooth flank modification, backlash distribution, and contact characteristics. The results indicate that controlling the meshing backlash through tooth flank modification shifts the contact pattern on the flexspline tooth surface from the heel to the toe region, reducing the maximum contact pressure by approximately 33.75% under rated torque and 31.03% during start-stop torque. This approach effectively mitigates the stress concentration and uneven load distribution observed in zero-backlash modification designs.

针对谐波传动中齿面修形设计与啮合性能之间的关系，提出了一种基于啮合间隙控制的啮合特性优化方法。首先，建立了柔键（滚刀加工）和圆花键（动力刨削加工）的几何模型。随后，在运动学建模的基础上，建立了包含齿面修正的谐波传动啮合间隙的计算方法。采用有限元分析方法研究了齿面修形、齿隙分布和接触特性之间的关系。结果表明：通过齿侧修形控制啮合间隙，使柔花键齿面接触模式由足跟区转移到趾部，最大接触压力在额定转矩下降低约33.75%，在启停转矩下降低约31.03%。这种方法有效地缓解了应力集中和不均匀荷载分布观察到的零侧隙修改设计。

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引用次数: 0

Accurate and robust state estimation for Stewart platform via error state Kalman filter with IMU and leg length fusion 基于误差状态卡尔曼滤波与IMU和腿长融合的Stewart平台精确鲁棒状态估计

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-11-25 DOI: 10.1016/j.mechmachtheory.2025.106297

Changyu Yue, Jinzheng Liu, Liwen Guan

Accurate, fast, and robust kinematic state estimation is essential for industrial applications of the Stewart platform. Conventional methods using leg lengths and forward kinematics are computationally intensive and sensitive to sensor noise. This paper proposes a novel error state Kalman filter (ESKF) framework that tightly fuses onboard inertial measurement unit (IMU) data with leg length measurements. By linearizing the system in the error state, the ESKF handles system nonlinearities more effectively and improves robustness to measurement noise. Additionally, the proposed scheme explicitly incorporates the closed-chain geometric constraints of the Stewart platform, thereby eliminating the need for iterative forward kinematics computations and enhancing computational efficiency. Extensive numerical simulations are conducted under both standard and extreme scenarios, including rapid motion, high sensor noise, reduced measurement availability, and sensor faults. The results indicate that the ESKF-based framework consistently outperforms conventional methods based on extended Kalman filter and forward kinematics with respect to accuracy, robustness, and real-time performance, highlighting its effectiveness for Stewart platform state estimation.

准确、快速、鲁棒的运动状态估计对Stewart平台的工业应用至关重要。使用腿长和正运动学的传统方法计算量大，对传感器噪声敏感。本文提出了一种新的误差状态卡尔曼滤波（ESKF）框架，该框架将机载惯性测量单元（IMU）数据与腿长测量数据紧密融合。通过在误差状态下对系统进行线性化处理，ESKF能更有效地处理系统非线性，提高对测量噪声的鲁棒性。此外，该方案明确地结合了Stewart平台的闭链几何约束，从而消除了迭代正运动学计算的需要，提高了计算效率。在标准和极端情况下进行了大量的数值模拟，包括快速运动、高传感器噪声、测量可用性降低和传感器故障。结果表明，基于eskf的框架在精度、鲁棒性和实时性方面始终优于基于扩展卡尔曼滤波和正运动学的传统方法，突出了其对Stewart平台状态估计的有效性。

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引用次数: 0

Simulation strategy for the wear process of spur gears considering operational time series 考虑运行时间序列的直齿齿轮磨损过程仿真策略

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-11-25 DOI: 10.1016/j.mechmachtheory.2025.106295

M. García-Pérez , M. Escalero , D. Cubillas , M. Olave , A. Fernández del Rincón

Gear transmissions are critical components in mechanical and transportation systems, where wear progressively alters tooth geometry, diminishes efficiency, and compromises reliability. Conventional wear prediction methods typically rely on simplified cyclic load spectra, which inadequately represent the highly variable operating conditions encountered in real-world applications. This discrepancy limits the accuracy of existing approaches, particularly under oscillatory regimes with non-stationary loads.

To overcome this limitation, this study introduces an efficient analytical framework for predicting wear in spur gears directly from operational time series of load and position. The proposed method builds upon physical wear models and accounts for the transient evolution of contact conditions, while maintaining low computational overhead. Validation against finite element simulations confirms that the approach accurately reproduces tooth wear profiles, yielding low relative errors across diverse loading scenarios.

The results underscore the importance of explicitly incorporating full time series data for reliable wear estimation under non-cyclic conditions. Beyond enhancing predictive accuracy, the proposed strategy offers practical advantages for integration into digital twin frameworks and predictive maintenance systems, where real-time or near-real-time assessments are essential.

齿轮传动是机械和运输系统的关键部件，磨损逐渐改变齿的几何形状，降低效率，并危及可靠性。传统的磨损预测方法通常依赖于简化的循环载荷谱，这不能充分代表在实际应用中遇到的高度可变的操作条件。这种差异限制了现有方法的准确性，特别是在非平稳载荷的振荡状态下。为了克服这一限制，本研究引入了一个有效的分析框架，用于直接从负载和位置的运行时间序列预测正齿轮的磨损。该方法建立在物理磨损模型的基础上，考虑了接触条件的瞬态演变，同时保持了较低的计算开销。对有限元模拟的验证证实，该方法准确地再现了牙齿磨损轮廓，在不同的加载场景中产生了较低的相对误差。结果强调了在非循环条件下明确合并全时间序列数据以进行可靠磨损估计的重要性。除了提高预测准确性外，所提出的策略还为集成到数字孪生框架和预测性维护系统提供了实际优势，在这些系统中，实时或近实时评估是必不可少的。

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引用次数: 0

A cable-driven parallel rehabilitation robot for active training of supine patients’ lower limbs 一种用于仰卧病人下肢主动训练的缆索驱动并联康复机器人

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-11-24 DOI: 10.1016/j.mechmachtheory.2025.106300

Yuze Zhang , Lu Bai , Rongjie Kang , Jian S. Dai , Zhibin Song

Patients with lower limb motor dysfunction typically require supine rehabilitation during early recovery. Compared to rigid-structure robots, cable-driven supine rehabilitation robots offer distinct safety and cost advantages. However, existing such robots are generally limited to passive training, particularly those with under-constrained cable-suspended structures. This study proposes a novel admittance model for the under-constrained cable-suspended system for active training in supine status, providing resistance along a specified trajectory. To enhance the training experience, two tunnel models orthogonal to the trajectory were proposed, rigid mode and compliant mode. They meet personalized rehabilitation requirements better by adjusting the impedance model parameters. To prove the efficiency of the under-constrained active training method, a cable-driven parallel robot (CDPR) for lower limb supine training was developed, achieving multi-joint lower limb movement via four cables. Considering that positioning of patient relative to the proposed robot is necessary for performing active training, an autonomous patient position identification method is introduced, without extra sensors. Experiments on the prototype confirmed the position identification method’s feasibility and the under-constrained active training control model’s effectiveness in both tunnel modes.

下肢运动功能障碍患者在早期康复时通常需要仰卧位康复。与刚性结构机器人相比，缆索驱动的仰卧康复机器人具有明显的安全性和成本优势。然而，现有的这类机器人通常仅限于被动训练，特别是那些缺乏约束的悬索结构。本研究提出了一种新的无约束悬索系统的导纳模型，用于仰卧状态的主动训练，提供沿指定轨迹的阻力。为了提高训练体验，提出了两种与轨迹正交的隧道模型：刚性模型和柔性模型。通过调整阻抗模型参数，可以更好地满足个性化康复需求。为验证无约束主动训练方法的有效性，研制了一种用于下肢仰卧训练的缆索驱动并联机器人（CDPR），通过四根缆索实现下肢多关节运动。考虑到患者相对于所提出的机器人的定位是进行主动训练所必需的，引入了一种不需要额外传感器的自主患者位置识别方法。原型机实验验证了位置识别方法的可行性和欠约束主动训练控制模型在两种隧道模式下的有效性。

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引用次数: 0

Numerical and experimental investigations on time-varying dynamic characteristics of three-point contact ball bearings 三点接触球轴承时变动态特性的数值与实验研究

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2025-11-22 DOI: 10.1016/j.mechmachtheory.2025.106299

Jilai Zhou , Zhong Luo , Lei Li , Tianyue Ma , Shiqiang Qiu , Xinping Luo

Three-point contact ball bearings (TPCBBs) are essential components in aero-engines. Their dynamic characteristics directly determine the mechanical system’s stability and safety. In order to analyze their time-varying dynamic characteristics, a quasi-static model of TPCBBs is proposed. The proposal of this model takes into account the equilibrium states of the balls and the inner rings comprehensively. Utilizing a dual-level iteration principle, the Newton-Raphson method serves as the solution method for this model. Notably, the Jacobian matrix within it is analytically derived. The overall stiffness variation, time-varying stiffness, contact forces, and contact angles are solved and analyzed. Furthermore, the validity of the proposed model is verified through experiments. The results indicate that the variation patterns and amplitudes of stiffness with external forces are different under different contact states. The contact forces supported by the inner and outer rings in the state of three-point contact show an increase contrasted with the state of two-point contact. And one of the inner rings will change from a load-free state to a loaded state.

三点接触球轴承（TPCBBs）是航空发动机的重要部件。它们的动态特性直接决定了机械系统的稳定性和安全性。为了分析多氯联苯的时变动态特性，提出了一种准静态模型。该模型综合考虑了球和内圈的平衡状态。利用双级迭代原理，Newton-Raphson方法作为该模型的求解方法。值得注意的是，其中的雅可比矩阵是解析导出的。对整体刚度变化、时变刚度、接触力和接触角进行了求解和分析。最后，通过实验验证了该模型的有效性。结果表明，在不同的接触状态下，刚度随外力的变化规律和幅度是不同的。与两点接触状态相比，三点接触状态下内外环所承受的接触力有所增加。其中一个内环会从无载荷状态变成有载荷状态。

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引用次数: 0