Mechanism and Machine Theory最新文献

A methodology for investigating the influence of hydrodynamic effects in gerotor type positive displacement machines 一种研究流体力学效应对转动式容积机影响的方法

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2024-11-16 DOI: 10.1016/j.mechmachtheory.2024.105836

Matthew Read

Positive displacement gerotor machines consisting of co-rotational and internally-meshed inner and outer rotors are widely used in liquid pumping applications. The necessary clearance gap between rotor profiles influences the contact behaviour and the internal leakage occurring between working chambers at different pressures. These depend on the dynamics of the idler rotor, which has not previously been investigated. This paper introduces a new approach to modelling the rotor dynamics, including the influence of hydrodynamic effects at the rotor contacts, bearing losses and the pumping torque. Epitrochoidal rotor profiles are used to investigate the influence of rotor geometry, clearances, and misalignment. The model provides insight into the effect of operating conditions, fluid properties, and material selection on the minimum film thickness achieved between the rotors, and the variation in clearance gap height. These results are essential for understanding how gerotor machines can be optimised to achieve high efficiency and a long operating life.

由同向旋转和内啮合内外转子组成的正排量异步电机广泛应用于液体泵送领域。转子轮廓之间的必要间隙会影响不同压力下工作腔之间的接触性能和内部泄漏。这些都取决于惰轮转子的动态特性，而此前尚未对此进行过研究。本文介绍了一种新的转子动力学建模方法，包括转子接触处的流体力学效应、轴承损耗和泵送扭矩的影响。外延转子剖面用于研究转子几何形状、间隙和不对中的影响。该模型有助于深入了解工作条件、流体特性和材料选择对转子之间达到的最小薄膜厚度以及间隙高度变化的影响。这些结果对于了解如何优化齿轮减速机以实现高效率和长使用寿命至关重要。

引用次数: 0

Two PRBMs of Euler spiral segments and their chained models for analyzing general curved beams in compliant mechanisms 两种欧拉螺旋线段 PRBM 及其链式模型，用于分析顺变机构中的一般曲线梁

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2024-11-15 DOI: 10.1016/j.mechmachtheory.2024.105838

Weisheng Wang, Mohui Jin, Zewei Li, Mingyu Qu, Xing Xu

Utilizing general curved beams can significantly enhance the mechanical properties of compliant mechanisms. However, the large-deflection analysis of general curved beams is still a challenging task. As one of the corresponding analysis methods for curved beams, chained pseudo-rigid-body model (CPRBM) is easy to implement, but requires a fine discretization to guarantee its analysis accuracy. To solve this problem, this paper proposes a new method for constructing coarse-discretization CPRBMs. The proposed method discretizes a curved beam into several segments, and regards each segment as an Euler spiral beam that can be modeled by PRBM. For this purpose, this paper derives the large-deflection equations of the Euler spiral beams with non-zero initial curvature. A 2R PRBM and a 3R PRBM are proposed for this kind of Euler spiral beams. The relationship between PRBM parameters and the initial shape of Euler spiral beams is established. Analysis cases and experiment are used to verify the chained models based on 2R/3R PRBMs. The results show that the coarse-discretization CPRBMs have higher computational efficiency and accuracy than the traditional CPRBM.

利用一般曲线梁可以显著提高顺从机构的机械性能。然而，一般曲线梁的大挠度分析仍然是一项具有挑战性的任务。作为曲线梁的相应分析方法之一，链式伪刚体模型（CPRBM）易于实现，但需要精细离散化才能保证其分析精度。为解决这一问题，本文提出了一种构建粗离散化 CPRBM 的新方法。本文提出的方法将曲线梁离散为若干段，并将每段视为可由 PRBM 建模的欧拉螺旋梁。为此，本文推导了初始曲率不为零的欧拉螺旋梁的大挠度方程。针对这种欧拉螺旋梁提出了 2R PRBM 和 3R PRBM。建立了 PRBM 参数与欧拉螺旋梁初始形状之间的关系。分析案例和实验验证了基于 2R/3R PRBM 的链式模型。结果表明，粗粒化 CPRBM 比传统 CPRBM 具有更高的计算效率和精度。

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引用次数: 0

Human–Machine coupled modeling of mandibular musculoskeletal multibody system and its application in the designation of mandibular movement function trainer 下颌骨肌肉骨骼多体系统的人机耦合建模及其在下颌骨运动功能训练器设计中的应用

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2024-11-13 DOI: 10.1016/j.mechmachtheory.2024.105848

Xinyue Wang , Jianqiao Guo , Jing Wang , Junpeng Chen , Qiang Tian , Chuanbin Guo

Many patients suffering from oral and maxillofacial tumors present trismus in the six months following mandibulectomy. Traditional mandibular movement function trainers (MMFT) cannot fulfill patient-specific targeted training, but mandibular musculoskeletal modeling can reveal patient-specific muscle recruitment patterns. This study proposed a digital rehabilitation framework for patients via mandibular musculoskeletal simulations. A flexible MMFT consisting of a soft intraoral airbag and a cable-driven extraoral trainer was designed. A human–machine coupling model was established to estimate the patient-specific muscle activations. Here, the intraoral trainer was modeled as a force vector, and the extraoral trainer was discretized by the flexible cable elements via an arbitrary Lagrangian–Eulerian description. Dynamic optimizations were performed to determine the patient-specific auxiliary forces, and the obtained values were utilized to design a quantitative rehabilitation plan. The effectiveness of the MMFT at increasing the magnitude of mandibular opening was validated with in vitro measurements. Numerical predictions for eight patients demonstrated that the proposed rehabilitation framework could improve the patient's jaw opening magnitude by an average of 3.8 ± 2.0 mm, highlighting the importance of subject-specific musculoskeletal modeling in mandibular rehabilitation.

许多口腔颌面部肿瘤患者在下颌骨切除术后的六个月内都会出现咀嚼障碍。传统的下颌骨运动功能训练器（MMFT）无法实现针对患者的针对性训练，但下颌骨肌肉骨骼模型可以揭示患者特定的肌肉募集模式。本研究通过下颌骨肌肉骨骼模拟为患者提出了一个数字化康复框架。研究人员设计了一种灵活的下颌肌肉骨骼模拟训练器（MMFT），该训练器由一个口内软气囊和一个电缆驱动的口外训练器组成。建立了一个人机耦合模型，以估计患者特定的肌肉激活。在该模型中，口内训练器被建模为力矢量，口外训练器则通过任意拉格朗日-欧勒描述由柔性线缆元素离散化。通过动态优化来确定患者特定的辅助力，并利用所获得的值来设计定量康复计划。体外测量验证了 MMFT 在增加下颌骨张开幅度方面的有效性。对八名患者进行的数值预测表明，所建议的康复框架可将患者的下颌打开幅度平均提高 3.8 ± 2.0 毫米，这凸显了针对特定对象的肌肉骨骼建模在下颌康复中的重要性。

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引用次数: 0

Multi-objective optimization design method for the dimensions and control parameters of curling hexapod robot based on application performance 基于应用性能的卷曲六足机器人尺寸和控制参数多目标优化设计方法

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2024-11-12 DOI: 10.1016/j.mechmachtheory.2024.105831

Yuguang Xiao , Ke Yin , Xianbao Chen , Zhijun Chen , Feng Gao

The curling hexapod robot is different from previous curling robots, which can mimic the throwing actions of curlers. To ensure its performance, the size and control parameters of the robot need to be optimized. However, there is still a lack of parameter design optimization methods for hexapod curling robots based on application performance and considering the coupling effects of size and control parameters. To meet this demand, this paper combines Simscape Multibody simulation modeling and genetic algorithm to propose a multi-objective optimization method for the dimensions and control parameters of curling hexapod robot based on application performance. This method uses Simscape Multibody to establish a parametric model of the curling robot, and proposes an optimization search method using genetic algorithms based on constraints and objective functions. Finally, the dimensions and control parameters of the curling robot that meet the application performance requirements are solved through the optimization method.

冰壶六足机器人不同于以往的冰壶机器人，它可以模仿冰壶运动员的投掷动作。为确保其性能，需要对机器人的尺寸和控制参数进行优化。然而，目前仍缺乏基于应用性能并考虑尺寸和控制参数耦合效应的六足冰壶机器人参数设计优化方法。针对这一需求，本文结合 Simscape 多体仿真建模和遗传算法，提出了一种基于应用性能的六足卷曲机器人尺寸和控制参数的多目标优化方法。该方法利用 Simscape Multibody 建立了卷曲机器人的参数模型，并根据约束条件和目标函数提出了利用遗传算法的优化搜索方法。最后，通过优化方法求解出满足应用性能要求的卷曲机器人的尺寸和控制参数。

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引用次数: 0

Redundancy parameterization and inverse kinematics of 7-DOF revolute manipulators 7-DOF 旋转机械手的冗余参数化和逆运动学

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2024-11-12 DOI: 10.1016/j.mechmachtheory.2024.105824

Alexander J. Elias, John T. Wen

Seven-degree-of-freedom (DOF) robot arms have one redundant DOF for obstacle and singularity avoidance which must be parameterized to fully specify the joint angles for a given end effector pose. Commonly used 7-DOF revolute (7R) industrial manipulators from ABB, Motoman, and KUKA and space manipulators like SSRMS or FREND are conventionally parameterized by the shoulder–elbow–wrist (SEW) angle for path planning and teleoperation. We introduce the general SEW angle which generalizes the conventional SEW angle with an arbitrary reference direction function. Redundancy parameterizations such as the conventional SEW angle encounter an algorithmic singularity along a line in the workspace. We introduce a reference direction function choice called the stereographic SEW angle which has a singularity only along a half-line which can be out of reach, enlarging the usable workspace. We prove all parameterizations have an algorithmic singularity. Finally, using the general SEW angle and subproblem decomposition, we provide efficient singularity-robust inverse kinematics solutions which are often closed-form but may involve a 1D or 2D search. Search-based solutions may be converted to finding polynomial roots. Examples are available in a publicly accessible repository.

七自由度（DOF）机械臂有一个冗余 DOF，用于避开障碍物和奇点，必须对其进行参数化，才能完全指定给定末端效应器姿势的关节角度。ABB、Motoman 和 KUKA 等公司生产的常用 7-DOF 旋转（7R）工业机械手以及 SSRMS 或 FREND 等空间机械手，在进行路径规划和远程操作时，通常使用肩-肘-腕（SEW）角度作为参数。我们引入了通用 SEW 角，它通过任意参考方向函数对传统 SEW 角进行了扩展。传统 SEW 角等冗余参数化会在工作空间中的一条线上遇到算法奇点。我们引入了一种称为立体 SEW 角的参考方向函数选择，它只在一条可能无法触及的半线上存在奇点，从而扩大了可用工作空间。我们证明了所有参数化都存在算法奇点。最后，利用一般 SEW 角度和子问题分解，我们提供了高效的奇异性稳妥的逆运动学解决方案，这些解决方案通常是闭式的，但可能涉及一维或二维搜索。基于搜索的解决方案可转换为寻找多项式根。示例可在一个可公开访问的资源库中获取。

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引用次数: 0

Bionic concept and synthesis methods of the biomimetic robot joint mechanism for accurately reproducing the motion pattern of the human knee joint 精确再现人体膝关节运动模式的仿生机器人关节机构的仿生概念和合成方法

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2024-11-12 DOI: 10.1016/j.mechmachtheory.2024.105832

Gaohan Zhu, Weizhong Guo, Shixuan Chu

The human knee joint (HKJ) exhibits a complex motion pattern characterized by a coupling of rolling and sliding movements as well as a moving instantaneous center of rotation. Reproducing this motion pattern in robot joints holds significant scientific and engineering value. This paper addresses two primary challenges in the bionic design of the biomimetic robot joint (BRJ): the difficulty in accurately reproducing the required motion and the absence of systematic structural synthesis methods for joint mechanisms. Firstly, a bionic concept is proposed to develop novel BRJ mechanisms based on the in-depth analysis and understanding of the HKJ, which realizes accurate reproduction of the HKJ motion pattern by introducing the higher pair. Then, task-oriented synthesis methods are further investigated to find innovative design solutions in a systematic and efficient way, including the profile synthesis of the higher pair and the structural synthesis of the overall mechanism. Finally, a case study of the four-link BRJ mechanism validates the effectiveness of the proposed method, resulting in innovative design schemes with potential applications.

人体膝关节（HKJ）表现出复杂的运动模式，其特点是滚动和滑动运动的耦合以及瞬时旋转中心的移动。在机器人关节中再现这种运动模式具有重要的科学和工程价值。本文探讨了仿生机器人关节（BRJ）仿生设计中的两个主要挑战：难以准确再现所需的运动以及缺乏关节机构的系统结构合成方法。首先，在深入分析和理解香港关节的基础上，提出了开发新型 BRJ 机构的仿生概念，通过引入高位对来实现香港关节运动模式的精确再现。然后，进一步研究了面向任务的合成方法，以系统、高效的方式找到创新设计方案，包括高位对的轮廓合成和整体机构的结构合成。最后，通过对四连杆 BRJ 机构的案例研究，验证了所提方法的有效性，从而提出了具有潜在应用价值的创新设计方案。

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引用次数: 0

Reconfiguration and compensation design method for single-DoF closed-chain leg mechanism 单道岔闭链支腿机构的重构和补偿设计方法

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2024-11-08 DOI: 10.1016/j.mechmachtheory.2024.105834

Jianxu Wu , Liang Zeng , Qiang Ruan , Jianduo Guo , Hui Yang , Liping Jing , Yan-an Yao

Compared with a wheeled robot propelled by a rotary drive, a legged robot equipped with multiple motors on a single leg possesses superior adaptability, while at the cost of high energy consumption and less velocity. Inspired by the California mite, the design method of reconfigurable closed-chain leg mechanism with single degree of freedom (DoF) is proposed for effective striding and smooth propelling. Furthermore, the lower-mobility closed-chain leg mechanism is more appropriate for obtaining high frequency and fast movement with the merits of simple control system and rotary drive. Firstly, a reconfigurable design is performed in the swing phase for a high-knee motion intermittently driven by a walking motor through dynamic coupling. Secondly, its fluctuations in vertical displacement and horizontal speed are compensated through the contact outline curve and variable speed input in the supporting phase. Finally, the simulated performance is analyzed and compared, and a prototype is fabricated for fluctuating and obstacle-crossing experiments.

与旋转驱动的轮式机器人相比，单腿装有多个电机的腿式机器人具有更优越的适应性，但代价是高能耗和低速度。受加利福尼亚螨虫的启发，我们提出了单自由度（DoF）可重构闭链腿机构的设计方法，以实现有效的跨步和平稳的推进。此外，低机动性闭链腿机构具有控制系统简单和旋转驱动的优点，更适合获得高频和快速运动。首先，通过动态耦合，在摆动阶段对由行走电机间歇驱动的高膝运动进行了可重构设计。其次，在支撑阶段，通过接触轮廓曲线和变速输入补偿其垂直位移和水平速度的波动。最后，对模拟性能进行了分析和比较，并制作了一个原型，用于波动和越障实验。

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引用次数: 0

Inertial analyses based on the generalized inertia matrix for parallel robots 基于广义惯性矩阵的并联机器人惯性分析

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2024-11-07 DOI: 10.1016/j.mechmachtheory.2024.105827

Zhou Zhou, Clément Gosselin

Analyzing the inertial properties is meaningful for parallel robots, especially those interacting with the environment. This paper provides tools for the analysis of the inertial properties of parallel robots based on the generalized inertia matrix (GIM). Since most interactions between the environment and robots happen through the mobile platform, the inertia of the whole robot reflected at the platform is considered. In this framework, the GIM is expressed in Cartesian space to yield inertial characteristics with a clear physical meaning. Then, the inertia of the whole robot is thereby reduced to an equivalent mass/inertia at the platform. Unlike for serial robots, obtaining the GIM of parallel robots in Cartesian space is complex due to the inherent closed-loop structures and the possibility of including two different types of redundancy. Two methods are proposed to solve the mentioned problems, which can simplify the derivations of the required GIMs for parallel robots. Detailed analysis and usages of the proposed methods are given based on different examples, and the results demonstrate the effectiveness of the proposed approaches.

分析惯性特性对并联机器人，尤其是与环境交互的并联机器人很有意义。本文提供了基于广义惯性矩阵（GIM）的并联机器人惯性特性分析工具。由于环境与机器人之间的大部分互动都是通过移动平台进行的，因此需要考虑整个机器人反映在平台上的惯性。在此框架下，GIM 用笛卡尔空间表示，以产生具有明确物理意义的惯性特征。然后，整个机器人的惯性被还原为平台上的等效质量/惯性。与串行机器人不同，并行机器人在笛卡尔空间中的 GIM 的获取非常复杂，这是因为其固有的闭环结构以及可能包含两种不同类型的冗余。本文提出了两种方法来解决上述问题，从而简化并联机器人所需 GIM 的推导过程。根据不同的示例对所提方法进行了详细分析和使用，结果证明了所提方法的有效性。

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引用次数: 0

Soft fingers with variable stiffness for space gripping tasks: An assessment 用于空间抓取任务的硬度可变的软手指：评估

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2024-11-06 DOI: 10.1016/j.mechmachtheory.2024.105830

Alfredo Puente-Flores, Hirohisa Kojima, Sajjad Keshtkar

The miniaturization of satellites and the problem of uncontrolled space debris demand highly flexible methods for space grippers. Soft grippers have surged as viable alternatives to overcome the limitations of traditional rigid grippers, such as lack of adaptability and dexterity. Although existent models have shown promising features, most have a high part count or make use of actuation systems that are inadequate for space, like pneumatic pumps or temperature-dependent materials. This work introduces novel designs of soft fingers that address the inherent challenges of grasping objects in space while overcoming these limitations. The proposed fingers use compliant structures based on several geometries of metamaterials. A detailed compliance and compressibility analysis is conducted using finite element methods to highlight the performance and behavior of each proposed design. Prototypes were fabricated, and their ability to exhibit different modes of actuation (variability in stiffness) by tendon compression was confirmed. The most apt design was selected and showcased in a three-fingered gripper to demonstrate the ability to grasp a given set of geometries with different sizes.

卫星的微型化和不受控制的空间碎片问题要求采用高度灵活的方法来制造空间机械手。为克服传统刚性机械手的局限性（如缺乏适应性和灵巧性），软机械手作为一种可行的替代方法迅速崛起。虽然现有的模型已经显示出良好的特性，但大多数模型的零件数量较多，或者使用的驱动系统（如气动泵或与温度有关的材料）不适合太空环境。本作品介绍了新型软手指设计，在克服这些限制的同时，解决了在太空中抓取物体的固有难题。所提出的手指采用了基于超材料几种几何形状的顺应性结构。使用有限元方法进行了详细的顺应性和可压缩性分析，以突出每种拟议设计的性能和行为。制作了原型，并确认了它们通过肌腱压缩表现出不同致动模式（刚度变化）的能力。选出了最合适的设计，并在三指机械手中进行了展示，以证明其能够抓取一组不同尺寸的几何体。

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引用次数: 0

Tensor based approach for tooth contact analysis of planar and spatial gearing contact 基于张量的平面和空间齿轮接触齿接触分析方法

IF 4.5 1区工程技术 Q1 ENGINEERING, MECHANICAL

Mechanism and Machine Theory

Pub Date : 2024-11-06 DOI: 10.1016/j.mechmachtheory.2024.105828

Michał Batsch

This paper presents a new method for analysing gear tooth contact, leveraging tensor notation and discrete differential geometry. Existing analytical and numerical methods often face challenges in convergence and computational efficiency. Our proposed approach involves defining a novel tensor notation and applying it to the gear tooth contact kinematics problem. By discretizing the tooth surfaces and using tensor operations, we can accurately determine the kinematics, path of contact, and transmission error of the gear pair. To validate our approach, we compared its results with those obtained from commercial software, KISSsoft and KiMOS. The results demonstrated high accuracy, with mean absolute errors below 0.08 for specific sliding, 0.003 for sliding factor, and

0.1 μ m

for transmission error. Furthermore, we applied our method to analyse non-involute gear types, such as S-gears, pin gearing and cosine gears. Our findings revealed the kinematic performance and contact characteristics of these gear types, providing valuable insights for gear design and optimization. In conclusion, the proposed tensor-based approach offers a promising alternative for gear tooth contact analysis, providing accurate and efficient results for a wide range of gear types.

本文提出了一种利用张量符号和离散微分几何分析齿轮齿接触的新方法。现有的分析和数值方法往往在收敛性和计算效率方面面临挑战。我们提出的方法包括定义一种新颖的张量符号，并将其应用于齿轮轮齿接触运动学问题。通过对齿面进行离散化并使用张量运算，我们可以精确地确定齿轮副的运动学、接触路径和传动误差。为了验证我们的方法，我们将其结果与商业软件 KISSsoft 和 KiMOS 得出的结果进行了比较。结果显示精度很高，具体滑动的平均绝对误差低于 0.08，滑动系数低于 0.003，传动误差低于 0.1μm。此外，我们还应用我们的方法分析了非渐开线齿轮类型，如 S 齿轮、销齿轮和余弦齿轮。我们的研究结果揭示了这些齿轮类型的运动学性能和接触特性，为齿轮设计和优化提供了有价值的见解。总之，所提出的基于张量的方法为齿轮齿接触分析提供了一种很有前途的替代方法，可为各种类型的齿轮提供精确、高效的结果。

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引用次数: 0