一种新型正铲液压挖掘机的运动学分析

基于平面12杆3自由度运动链图拓扑图库,提出一种复杂多环耦合新型正铲液压挖掘机构。基于运动链环路理论和模块化图形组态,对机构进行运动学建模。考虑到铲斗的水平推铲作业能力是正铲液压挖掘机的一个重要性能指标,基于MATLAB平台,对机构运动学进行仿真分析。仿真结果表明,该新型机构具有良好的水平推铲能力。通过给出5组不同的液压缸尺寸数据,利用运动学位置正解与反解相互验证,证明了运动学位置分析的准确性。基于运动学正解分析新型正铲液压挖掘机铲斗的理论可达工作空间,得出该挖掘机构的铲斗姿态角保持在100°~120°时水平挖掘的工作空间最大,满足正铲挖掘机水平挖掘作业的要求。研究结果为该新型正铲液压挖掘机构的设计和使用提供参考。     

基于虚拟样机技术的机构创新设计

以运输皮带钉扣机的开发研制为例,利用虚拟样机技术,对整个产品研发过程进行研究.建立了基于概念设计的初始模型并对机构进行优化,应用ADAMS、SOLIDWORKS、ANSYS等软件分别对钉扣机进行了动力学和运动学分析、虚拟装配与干涉检验及有限元强度分析,并且通过物理样机的试验来验证虚拟样机的仿真分析的正确性.     

Optimal setup for five-axis machining

This paper presents a new optimization model designed to minimize kinematics error introduced by the initial setup of a five-axis milling machine. An initial setup consists of the position and orientation of the workpiece with respect to the mounting table and, optionally, the machine's initial configuration. Given a set of cutter contact points and tool orientations, a least-squares optimization procedure finds the optimal setup parameters. Since the set of optimization parameters depends on the machine's characteristics, three basic types of five-axis kinematics are introduced. The classification into types depends on the sequence of positions of the machine's rotary axes in its kinematics chain. For each type, sets of invariant and dependent variables are identified, a corresponding system of nonlinear equations is constructed, and then the system is solved numerically. The method is not only efficient, but also provides tangible accuracy increases in tests on practical machining problems.     

回转关节型气动机械手的逆运动学分析

提出了一种新的推导回转关节型多自由度气动机械手逆运动学方程的方法,进而给出逆运动问题新的求解方法。此方法不需要对机械手末端位姿进行坐标变换,另外在解的推导过程中避免了大量的逆矩阵相乘,方法简单,从而可提高整个机器人系统的控制速度,便于工业控制和仿真。仿真证明了所提方法的正确性。     

液压缸双梁铰接式剪叉机构动力学及运动学分析

对液压缸双梁铰接式剪叉机构进行动力学及运动学分析,推导出液压缸活塞运动速度与剪叉机构升降平台速度的关系式及活塞推力与机构载荷的关系式,并根据实例计算结果描绘出恒定载荷下活塞推力与剪叉机构升降平台速度随平台起升高度变化曲线,为液压系统流量、压力的确定以及液压缸优化布置提供了理论依据。     

An experimental and modeling study of the thermomechanical behavior of an ABS polymer structural component during an impact test

An experimental and modeling study of the thermomechanical behavior of an ABS polymer structural component during an impact test is presented. The structural component was a heel of a woman's shoe made of ABS polymer material reinforced or not by a pin. Kinematics and thermal full field measurement techniques were used to observe the material and structural component during preliminary experimental tensile and impact tests. With the kinematic fields it was possible to identify the stress–strain response, which takes the necking localization into account. Positive volume variations were also observed during these tensile tests, which were associated with the crazing damage mechanisms in this type of polymer. The thermal fields measured during these tests showed high temperature variations (a few K to 25 K) in the zone where strain was localized.     

Recent Applications of Descriptive Geometry to Mechanical Engineering

This is a brief summary of a paper presented at the 5th Japan-China Joint Conference on Graphics Education in Osaka 2001.     

Evaluation of eye,head and trunk coordination during target tracking tasks

This study tested the feasibility of a method to synchronise and to evaluate eye, head and trunk movement patterns during target tracking tasks performed by 10 subjects. A projected central target was randomly repositioned at 40° and 70° of rotation to the left and right. Subjects were instructed to change gaze as quickly as possible. Head and trunk motion was measured using a motion analysis system, and eye movement was measured using an eye-tracker; all data were synchronised. For healthy subjects, the eye moved faster than the head, there was no trunk movement and the head moved more than the eye to reach further displaced targets. The method tested was feasible, and it could be used to evaluate eye, head and trunk movement patterns of subjects with injuries such as whiplash and concussions.

Practitioner Summary: Studies of eye, head and trunk movements using synchronised methods are needed. We tested the feasibility of a method to synchronise and evaluate eye, head and trunk movement patterns. The method tested was feasible, and it could be used to evaluate movement patterns of subjects with injuries such as whiplash.     

双机械臂协调系统的一类最优轨迹规划方法

针对双机械臂搬运单一物体的协调操作系统，提出了一类有效的最优关节轨迹规划方法。该法在机械臂的关节空间内采用分段归一化的无因次量，将其运动轨迹与运动时间解耦，运用非线性规划法优化无因次量运动轨迹。将所规划的无因次轨迹方程作为机械臂产生实际运动轨迹的发生器，由双臂的运动学约束条件和爪端所允许的不协调误差及各手臂的取道点，即可快速生成所期望的系统运动轨迹。为保证双臂能充分协调运动，提出了调整因子的概念。