Optimal design of a 3-leg 6-DOF parallel manipulator for a specific workspace

Researchers seldom study optimum design of a six-degree-of-freedom(DOF) parallel manipulator with three legs based upon the given workspace. An optimal design method of a novel three-leg six-DOF parallel manipulator(TLPM) is presented. The mechanical structure of this robot is introduced, with this structure the kinematic constrain equations is decoupled. Analytical solutions of the forward kinematics are worked out, one configuration of this robot, including position and orientation of the end-effector are graphically displayed. Then, on the basis of several extreme positions of the kinematic performances, the task workspace is given. An algorithm of optimal designing is introduced to find the smallest dimensional parameters of the proposed robot. Examples illustrate the design results, and a design stability index is introduced, which ensures that the robot remains a safe distance from the boundary of sits actual workspace. Finally, one prototype of the robot is developed based on this method. This method can easily find appropriate kinematic parameters that can size a robot having the smallest workspace enclosing a predefined task workspace. It improves the design efficiency, ensures that the robot has a small mechanical size possesses a large given workspace volume, and meets the lightweight design requirements.     

基于MATLAB的破碎机动力学参数优化设计

破碎机动力学参数设计包含机构平衡重、拉杆弹簧计算载荷、飞轮转动惯量等动力学参数的优化设计,是破碎机设计极其重要的内容.破碎机在运转过程中,其偏心轴、动颚、肘板等运动件都具有一定的加速度,会产生很大的惯性力而且大小、方向呈周期性变化.这些惯性力在运动副中引起附加动载荷,是破碎机零件磨损、机器振动的主要原因.破碎机动力学参数优化设计就是通过优化计算,获得最优的平衡条件,使机构总的惯性力平衡,其根本目的就是减小运动件的惯性力引起的附加动载,消除其有害影响,以确保破碎机运转稳定、可靠,降低机器的振动和噪声,提高设备的寿命和效率.以国内广为生产、使用的PE600×900破碎机为研究对象,利用MATLAB的优化功能,在进行运动学、动力学分析,建立一系列运动方程和力学模型之基础上,采用最优动力平衡法,在MATLAB环境下对破碎机机构平衡重进行优化设计.通过优化计算获得机构平衡重及其方向角的最佳值,使随机构位置而变化的振动力降低到最小.     

冗余度机器人研究动向

冗余度机器人，从运动学的观点来说是指完成某一特定任务时，机器人具有多余的自由度。多余的自由度可用来改善机器人的运动及动力学特性，如增加灵活性，躲避障碍、回避奇异、优化主运动任务下的辅助操作指标，优化关节速度，加速度，力矩，能量等。冗余度机器人由于其自身众多优点而越来越受到人们的关注。本文介绍冗余度刚性机器人、冗余度柔性机器人研究的发展现状及存在的问题。     

一种铆接机械手的运动精度可靠性分析

介绍了一种六自由度工业机器人的运动精度可靠性分析方法。通过分析一种铆接机械手的结构,基于D-H坐标法,建立运动数学模型,并考虑加工和装配过程中尺寸误差和间隙误差的随机性,将结构参数和运动变量误差视为随机变量,建立运动误差模型,结合机构运动学和可靠性理论,构建机械手运动精度可靠性模型。通过算例,验证了该方法的可行性,为该类型工业机器人的可靠性设计和结构优化提供了一定的理论参考。     

基于神经网络的冗余度机器人动态最优化控制

进行了冗余度机器人动态最优化控制的研究,由于局部优化方法有一定的局限性,研究中采用了全局优化方法,基于全局优化的思想,提出了一种冗余度机器人的动态优化控制算法,由于控制算法在数值求解时的困难性,在算法中应用了神经网络,用其来逼近复杂的非线性函数,使问题求解得以简化,通过仿真验证,此控制算法能够获得良好的动态性能,运算速度快,具有工程应用的可行性。     

Evolutionary bi-criteria optimum design of robots based on task specifications

The optimum robot structure design problem based on task specifications is an important one, since it has greater influence on manipulator workspace design, vibrations of the manipulator during operation, manipulator efficiency in the work environment and power consumption. In this paper, an optimization robot structure problem is formulated with the objective of determining the optimal geometric dimensions of the robot manipulators considering the task specifications (pick and place operation). The aim is to minimize torque required for motion and maximize manipulability measure of the robot subject to dynamic, kinematic, deflection and structural constraints with link physical characteristics (length and cross-sectional area parameters) as design variables. In this work, five different cross-sections (hollow circle, hollow square, hollow rectangle, C-channel and I-channel) have been experimented for the link. Three evolutionary optimization algorithms namely multi-objective genetic algorithm (MOGA), elitist nondominated sorting genetic algorithm (NSGA-II) and multi-objective differential evolution (MODE) are used for the optimum structural design of 2-link and 3-link planar robots. Two methods (normalized weighting objective functions and average fitness factor) are used to select the best optimal solution. Two multiobjective performance measures namely solution spread measure and ratio of non-dominated individuals are used to evaluate the Pareto optimal fronts. Two more multiobjective performance measures namely optimiser overhead and algorithm effort, are used to find computational effort of optimization algorithm. The results obtained from various techniques are compared and analyzed.     

Tricept机器人的尺度综合方法研究

Tricept机器人是目前商业上最为成功的并联机器人之一。提出一种Tricept机器人中三自由度并联机构的最优尺度综合方法。该方法首先导出尺度参数间的关系,其次构造一种均衡条件数全域均值及其极差间矛盾的综合操作性能指标,进而将尺度综合问题归结为一类双参数优化问题。该方法对掌握这类及其他并联机构的运动学设计理论有一定指导意义。     

空间冗余度机器人动力学优化的虚拟仿真研究

这里提出了一种基于虚拟设计技术的空间冗余度机器人动力学优化分析新方法。首先构建空间冗余度机器人的虚拟样机模型，然后对末端任务空间自由度采用速度三次插值并参数化，从而得到参数化的任务空间轨迹；并以电机力矩平均值差值的乘积以及电机的力矩和作为目标函数，进行机器人的动力学优化研究。研究表明，本方法是可行的，有较好的可靠性和实用价值。     

风电叶片管道内窥履带机器人的设计与运动分析

针对风电叶片内部变截面、大坡度、多障碍等环境特征,设计了一种四自由度关节的履带式管道内窥机器人用于叶片内部检测和维护,并对该机器人的运动学特征进行了分析。该机器人包括前后履带式移动平台和中间四自由度关节三部分。四自由度关节由蛇形机器人常用的二自由度十字关节和前后旋转模块组成,通过四个电机之间的配合,可实现抬头、转弯、多角度翻转、爬坡等功能。介绍了该四自由度关节的基本结构、动力系统和连接机构等;基于D-H方法对机器人的正逆运动学问题进行分析,得到了机器人的工作空间,并用CoppeliaSim对机器人进行了整体动态仿真;根据设计方案研制了机器人样机,并通过实验对机器人各功能的实现进行了验证。     

一类1T2R并联机构拓扑结构综合及优选

研究了一类1T2R并联机构拓扑结构综合和优选。应用平面机构的组成原理和约束特性,将1T2R并联机构拓扑结构视为由一条串接一转动副的1T1R平面并联运动链和两条空间无约束主动支链组成。统筹考虑机构位姿能力恰当性、支链结构力学合理性、机器人模块可重构性、位置逆解简易性和动平台结构紧凑性等准则,完成1T2R并联机构拓扑结构优选及性能验证。在此基础上,提出一种可继承Tricept机器人优点的新型五自由度混联机器人模块,该模块具有与Tricept机器人完全相同的运动学性能,且绝大部分部件可与Tricept机器人互换。     

一种新型4自由度高速并联机械手动力尺度综合

研究一种可实现SCARA运动的新型4自由度高速并联机械手动力尺度综合方法。简要阐述该机构中由可变菱形动平台和齿轮增速机构生成绕z轴转动的传动原理。在建立运动学和刚体动力学模型基础上,利用直接和间接雅可比代数特征构造出两类可用于描述运动/力在链内和链间传递能力的压力角,并提出一种基于单轴最大驱动力矩全域最大值最小的动力学性能评价指标。在满足工作空间与机构尺度比、可装配条件等几何约束和运动学性能约束下,综合出一组可使得系统刚体动力学性能全域最优的尺度参数,并利用Adept拓展轨迹预估出电动机参数。     

柔性冗余度机器人振动主动控制

采用振动主动控制方法降低柔性冗余度机器人的弹性动力响应。设计了具有压电作动器与应变传感器的机敏连杆 ,建立了离散时变受控系统的状态空间表达式。利用 Bellman动态规划设计 L QR状态反馈控制器 ,并提出了一种状态估计的近似方法。平面 3R柔性冗余度机器人的仿真算例表明 ,采用该方法可以使柔性冗余度机器人的动力学性能得到显著的改善     

仿生机器蟹步行腿结构设计及运动学、动力学分析

仿生机器蟹是一种采用微型直流伺服电机驱动的仿生步行机器人，本文详细介绍了机器蟹步行腿设计及其运动学分析、动力学分析。在对仿生机器蟹运动学特性分析的基础上得出优化结构参数，并应用于实际系统设计。同时利用先进的动力学仿真软件建立了仿生机器蟹三维仿真模型，仿真结果验证了运动学和动力学数学建模的正确性，及结构设计的可行性。     

微型足球机器人惯性分析及结构优化设计

介绍了足球机器人系统的基本设计思路,对该系统的惯性特性进行了重点分析,提出了控制机器人惯性特性的一般方法.并结合优化设计原则讨论了几个重要的设计指标,为微型足球机器人结构优化设计提供理论依据和帮助.     

Development of a redundant anthropomorphic hydraulically actuated manipulator with a roll–pitch–yaw spherical wrist

The demand for redundant hydraulic manipulators that can implement complex heavy-duty tasks in unstructured areas is increasing; however, current manipulator layouts that remarkably differ from human arms make intuitive kinematic operation challenging to achieve. This study proposes a seven-degree-of-freedom (7-DOF) redundant anthropomorphic hydraulically actuated manipulator with a novel roll–pitch–yaw spherical wrist. A hybrid series–parallel mechanism is presented to achieve the spherical wrist design, which consists of two parallel linear hydraulic cylinders to drive the yaw/pitch 2-DOF wrist plate connected serially to the roll structure. Designed as a 1R PRRR-1S PU mechanism (“R”, “P”, “S”, and “U” denote revolute, prismatic, spherical, and universal joints, respectively; the underlined letter indicates the active joint), the 2-DOF parallel structure is partially decoupled to obtain simple forward/inverse kinematic solutions in which a closed-loop subchain “R PRR” is included. The 7-DOF manipulator is then designed, and its third joint axis goes through the spherical center to obtain closed-form inverse kinematic computation. The analytical inverse kinematic solution is drawn by constructing self-motion manifolds. Finally, a physical prototype is developed, and the kinematic analysis is validated via numerical simulation and test results.     

QUADRATIC OPTIMIZATION METHOD AND ITS APPLICATION ON OPTIMIZING MECHANISM PARAMETER

In order that the mechanism designed meets the requirements of kinematics with optimal dynamics behaviors, a quadratic optimization method is proposed based on the different characteristics of kinematic and dynamic optimization. This method includes two steps of optimization, that is, kinematic and dynamic optimization. Meanwhile, it uses the results of the kinematic optimization as the constraint equations of dynamic optimization. This method is used in the parameters optimization of transplanting mechanism with elliptic planetary gears of high-speed rice seedling transplanter with remarkable significance. The parameters spectrum, which meets to the kinematic requirements, is obtained through visualized human-computer interactions in the kinematics optimization, and the optimal parameters are obtained based on improved genetic algorithm in dynamic optimization. In the dynamic optimization, the objective function is chosen as the optimal dynamic behavior and the constraint equations are from the results of the kinematic optimization. This method is suitable for multi-objective optimization when both the kinematic and dynamic performances act as objective functions.     

Kineto-elastodynamic balancing of 4R-four bar mechanisms combining kinematic and dynamic stress considerations

When a mechanism runs at high speed and has elastic links, its links vibrate under the action of forces present on the mechanism. The acceleration field resulting from the vibration of the links develops additional interia forces called kineto-elastodynamic (KED) inertia forces. The present paper takes into account the contribution of the KED inertia forces towards the shaking force and shaking moment while balancing planar mechanisms. Combining kinematic design and dynamic stress considerations an optimal kinematic design of the mechanism satisfying the given aim and optimal cross-sectional areas of the links were determined such that the shaking force trasmitted to the foundations due to the combined effect of rigid-body inertia forces and KED inertia forces is a minimum.     

Multi-objective Optimization of a Parallel Ankle Rehabilitation Robot Using Modified Differential Evolution Algorithm

Dimensional synthesis is one of the most difficult issues in the field of parallel robots with actuation redundancy. To deal with the optimal design of a redundantly actuated parallel robot used for an...     

5R柔性并联机器人系统运动微分方程

为了描述平面5R柔性并联机器人的运动学和动力学特性,需要建立机器人的运动微分方程。针对刚性活动平台和柔性杆件的运动学耦合特点,改进了一套适用于刚体、柔性体耦合的有限元建模方法,推导出单元弹性广义坐标相对于系统弹性广义坐标的转换矩阵,综合考虑了科氏阻尼、离心刚度和几何非线性的影响,利用运动弹性动力学理论,建立了平面5R柔性并联机器人的运动微分方程,避免了采用运动学和动力学约束方程的弊端,提高了建模精度。计算实例表明,该方程反映了机器人的弹性振动特性,杆件的弹性变形对机器人的运动误差具有重要影响。     

汽车驾驶机器人换档机械手的优化设计

阐述我国首台汽车驾驶机器人换档机械手机构的工作原理、运动学分析及优化设计。经过优化设计，整个换档机械手机构的尺寸基本确定，摘、进档运动只由θ３１确定，选档运动只由θ２１确定。