一种新的六自由度并联机器人分散控制方法

结合六自由度并联机器人机构的特点.提出一种新的分散控制方法.首先依据机构特点指出了关节空间内惯性矩阵块对角占优特性,从而将耦合强烈的邻近支路加以整体考虑,即分散控制3个两输入两输出子系统;然后将惯性矩阵的逆分解为块对角矩阵与耦合矩阵之和,从而得到每个子系统的动力学方程;最后针对子系统负载随机构运动而变化的特点引入线性变参数(LPV)控制方法,降低了使用线性定常控制器的保守性.仿真结果表明了所提出方法的有效性.     

一种双惯性轮空间倒立摆及其动力学建模和分析

针对现有的惯性轮倒立摆在模拟多自由度不稳定系统的局限性,提出了一种双惯性轮空间倒立摆系统,其具有四个自由度和两个控制量,可同时模拟不稳定系统俯仰和滚转姿态控制。运用拉格朗日方法建立了双惯性轮空间倒立摆的动力学模型,分别采用模型退化、数值仿真验证了所建立的模型的正确性,并分析了双惯性轮空间倒立摆的动力学特性。建立的双惯性轮空间倒立摆可应用于多自由度非平稳系统的模拟实验,提出的物理结构、模型和相关分析结论为双惯性轮空间倒立摆系统的进一步研究奠定了理论基础。     

模拟后坐离心环境对惯性点火器钟表机构

为揭示模拟后坐离心试验环境对某惯性点火器用于发射环境识别的钟表机构工作时间的影响,优化试验设计,用Adams建立该钟表机构工作过程仿真模型,得到其工作时间与离心半径和离心过载的关系曲线.钟表机构工作时间随离心过载的增大而单调增长;离心过载不变时,离心半径越大,钟表机构工作时间越接近模拟后坐环境下的工作时间.     

基于重力矢量积分的SINS对准算法误差分析

针对基于重力矢量积分的捷联惯导初始对准算法,分析了惯性器件误差和线运动干扰对对准精度的影响。推导了惯性器件误差与对准失准角之间的解析表达关系,指出可从初始欧拉角估计值中提取陀螺漂移信息,实现陀螺的在线标定。理论分析表明,该算法将传统解析对准算法对角运动的敏感转化为对线运动的敏感,线运动干扰成为影响算法对准精度的主要因素。仿真试验验证了上述分析的合理性。     

勃郎宁9mm大威力手枪自动机运动仿真分析

分析了勃郎宁9mm大威力改进型手枪自动机及击发发射机构的动作原理及设计思想,利用虚拟样机仿真技术对自动机后坐与复进时的运动进行仿真分析计算,得到了各运动构件运动特性曲线,并绘制了进弹路线、抛壳路径。通过虚拟样机仿真分析,说明其设计合理,能很好地完成自动动作。     

并联机器人机构的虚拟样机运动仿真实验研究

以先进制造装备中的机器人工作台为应用背景,研究一种具有四个自由度的新型并联机器人机构。对这种机构的结构作了简要介绍,对其运动特性和自由度作了理论分析和计算。运用虚拟样机技术,在ADAMS软件平台上构建该并联机器人机构模型。按照机构的结构几何尺寸计算各转动副的位置坐标,创建连杆等零件和各转动副,设定驱动副和初速度以及进行运动仿真实验。对仿真结果进行分析。实验和分析结果证明理论分析方法是正确的。此外还说明,完全可以运用ADAMS软件完成并联机构的运动特性分析虚拟样机实验,为并联机构的结构综合提供了一种新的实验方法。     

3-CPS并联机器人的机构分析及仿真研究

由于传统Stewart平台有支链运动耦合和工作空间小的缺点,因此以串并联混合机构形式,提出一种新型的六自由度并联机构。为解决运动耦合和工作空间小的问题,并且在保证运动精度的前提下降低生产成本,主要运用矩阵代数工具分析了该机构的反向运动学,运用数值迭代解法分析了该机构的正向运动学,并对该机构的速度加速度进行了分析。通过Adams仿真软件对运动学模型进行数值验证及分析,深入研究了该机构的运动特性和线性度,实验结果证明这种机构具有运动解耦特性和旋转对称性,可以进行良好的线性运动。通过Matlab仿真软件分析对机构驱动器的误差进行研究,实验结果证明该机构用于天文望远镜支撑平台时,保证动平台的运动精度的同时降低了生产成本。     

具有7自由度和双球型髋关节的仿人机器人下肢运动分析与规划

提出了具有7自由度和双球型髋关节的仿人机器人下肢机构．它和传统的6自由度双足步行机构相比,具有下述两大优点．首先双球型髋关节使机器人在不增加腰部关节的情况下实现腰部的基本运动功能,使机器人能够直立行走;其次在给定腰和足部位置时,它也能和人类一样实现转动双腿的动作．本文还对该复杂机构进行了运动特性分析、运动学求解、运动规划和实验验证．     

4-RP(RR)R并联机器人运动仿真

该文给出一个新型的少自由度并联机器人机构4-RP（RR）R的动态仿真。文中对此机构进行了反解分析,确立了此机构运动平台的位置输出与移动副输入及各空间顶点位置的关系。在此基础上,利用Matlab软件模拟出实物动态图,并对利用几何分析法做出的速度曲线、加速度曲线与利用虚设影响系数法求出的速度曲线、加速度曲线进行分析比较,进一步说明了机构本身的运动特性,以及虚设影响系数法对少自由度并联机器人机构4-RP（RR）R求解的正确性。     

基于ADAMS的某型冲锋枪自动机动力学仿真和分析

为研究某型冲锋枪自动机运动规律和动力学特性,进而探究导气孔大小对自动机运动循环的影响,首先使用UG软件建立该枪自动机的三维实体模型,其次在ADAMS软件中建立虚拟样机,利用MATLAB软件对内弹道和导气室压力曲线进行拟合,对该枪的单发射击进行仿真,得到了枪机和枪机框的位移速度曲线、复进簧压力曲线等动力学特性,对比仿真结果与试验数据,说明虚拟样机模型具有较高的可行性,最后仿真分析导气孔大小对自动机运动循环的影响,仿真结果表明,随着导气孔直径增大,后坐速度和后坐撞击变大,复进到位速度明显提高,复进时间显著降低,自动循环时间相对缩减,为产品优化设计提供理论参考。     

提高加速度开关抗振动能力的设计

加速度开关是一种由弹簧—质量系统构成的惯性测量装置,当进行随机振动试验时,与敏感质量块刚性相连的弹簧片会随着质量块的运动受力,其中一些剪切力和扭转力是加速弹簧片破坏的主要环境力。为了保护弹簧片,可以采用一种力的隔离技术,使得弹簧片除了受到应受的工作方向的力外,尽量避免受到剪切力和扭转力的作用,采用这种技术设计的钢珠式加速度开关有效地解决这个问题,试验证明:产品的抗振能力得到了提高。     

An application of interactive computer graphics for simulation of vibratory systems

Computer simulation of two vibratory systems composed of mass. spring, and dashpot el ements is described. The first system has one degree of freedom and it undergoes damped-free vibration. The second system undergoes damped-forced vibration with two degrees of freedom. The use of refresh graphics with full interaction in real time facilitates a comprehensive parametric study of the system and the programs can be used as teaching and design aids.     

基于MEMS技术的低g值微惯性开关的设计与制作

惯性开关是一种感受惯性加速度,执行开关机械动作的精密惯性装置.选用典型的"弹簧-质量-阻尼"结构,研制了一种基于平面矩形螺旋梁的低g值(1gn～30gn)微惯性开关.惯性敏感单元由一个方形质量块和支撑它的两根螺旋梁组成,采用ANSYS有限元软件对其进行了仿真分析.采用MEMS体硅加工工艺和圆片级封装技术,包括KOH腐蚀...     

Comparison of various balance systems for energy conservation in a vertically articulated manipulator with three joints

It is important to conserve dissipated energy from machines in order to reduce global warming. This paper discusses energy conservation in a vertically articulated three-joint manipulator with a rotation–pivot–pivot structure. The amount of dissipated energy can be decreased by canceling out the gravity on the second and the third links of the manipulator using a mass balancer or a spring balancer. Mass balancers are designed optimally by diminishing the inertia matrix so that the amount of dissipated energy can be minimized. Three kinds of counterbalancer systems, which include a mass–mass balancer, a spring–mass balancer and a spring–spring balancer, are designed optimally. Energy is compared among the three types of counterbalancers mounted on a three-link manipulator in simulation. The simulation indicates that a spring–mass balancer is more practical because of the considerable energy conservation effect and simplicity in implementation. In order to confirm the simulation results, the dissipated energy is measured experimentally using a practical system of a directly-driven manipulator on which a suboptimal mass–mass balancer or a spring–mass balancer is mounted. As a result, the measured dissipated energy is approximately the same as the result obtained by simulation.     

Multi-objective optimization by genetic algorithm of structural systems subject to random vibrations

This paper deals with a multi-objective optimization criterion for linear viscous-elastic device utilised for decreasing vibrations induced in mechanical and structural systems by random loads. The proposed criterion for the optimum design is the minimization of a vector objective function. The multi-objective optimization is carried out by means of a stochastic approach. The design variables are the device frequency and the damping ratio. As cases of study, two different problems are analysed: the base isolation of a rigid mass and the tuned mass damper positioned on a multi degree of freedom structural system subject to a base acceleration. The non-dominated sorting genetic algorithm in its second version (NSGA-II) is adopted to obtain the Pareto sets and the corresponding optima for different characterizations of the system and input.     

Experimental determination of the hydrodynamic coefficients of an underwater manipulator

A single degree‐of‐freedom (DOF) manipulator arm with a rectangular cross section is built to investigate the hydrodynamic effects, including drag force, added mass, and the moments induced by these forces. The drag–velocity relationships (linear and angular) are experimentally established and the drag force/moment coefficients are deduced. The added mass and the added moment of inertia are determined for the first time through the relationship between the added mass of the manipulator and its acceleration. These data are very useful for developing the dynamic model and therefore the optimum control of underwater manipulators. ©1999 John Wiley & Sons, Inc.     

Solution of free vibration equation of elastically supported Timoshenko columns with a tip mass by differential transform method

In this study free vibration analysis of a Timoshenko column with a tip mass having rotary inertia is carried out by both exact solution and differential transform method (DTM). The support of the system is modeled by an elastic spring against rotation. Fixity factor is used to define the relative stiffness of the elastic connection and the column. The governing equation of the column is solved by the separation of variables method including the rotatory inertia to get the exact solution. The same problem is also solved by DTM algorithm and the results are compared with the ones of exact solution. The comparison tables are presented in numerical analysis to show that a very good agreement is observed for DTM.     

A Dynamic Analysis of a Spatial Manipulator to Determine Payload Weight

This paper presents a methodology whereby the payload weight of a serial manipulator can be determined from a minimum set of sensor data, i.e., joint angle and joint torque measurements. The particular manipulator geometry that is analyzed is a four degree‐of‐freedom serial chain that is commonly used in excavator systems. It was quite remarkable that a relatively simple solution was obtained for the payload weight considering that there are a total of nine unknown moments and cross moments of inertia of the payload together with the unknown location of the center of mass. Example calculations are presented. © 2003 Wiley Periodicals, Inc.     

Semiactive control of a vibrating system by means of electrorheological fluids

A control scheme is designed for the purpose of suppression of vibratory motion of a dynamical system. The efficacy and robustness of the controller vis a vis unknown but bounded disturbances and state measurement errors is investigated analytically and numerically. As an example of a dynamical system we consider a single degree of freedom mass—spring—damper system that is excited by an unknown force. The control scheme presupposes that the spring and damping coefficients can be varied within prescribed bounds, albeit not independently. The construction of such a semiactive controller can be realized by using the properties of so calledelectrorheological fluids (see [1] for relevant experimental investigations). The called for changes in spring and damping properties can be effected in microseconds since the control does not involve the separate dynamics (inertia) of usual actuators. The design of the controller is based on Lyapunov stability theory which is also utilized to investigate the stabilizing properties of the controller. To accommodate state measurement errors the proposed control scheme is combined with afuzzy control concept. Simulations are carried out for examples of periodic, continuous nonperiodic, discontinuous periodic and random excitation forces.     

Effects of position quantization and sampling rate on virtual-wall passivity

The "virtual wall" is the most common building block used in constructing haptic virtual environments. A virtual wall is typically based on a simple spring model, with unilateral constraints that allow the user to make and break contact with a surface. There are a number of factors (sample-and-hold, device dynamics, sensor quantization, etc.) that cause virtual walls to demonstrate active (nonpassive) behavior, destroying the illusion of reality. In this paper, we find an explicit upper bound on virtual wall stiffness that is a necessary and sufficient condition for virtual wall passivity. We consider a haptic display that can be modeled as a mass with Coulomb-plus-viscous friction, being acted upon by two external forces: an actuator and a human user. The system is equipped with only one sensor, an optical encoder measuring the position of the mass. We explicitly model the effects of position resolution, which has not been done in previous work. We make no assumptions about the human user, and we consider arbitrary constant sampling rates. The main result of our analysis is a necessary and sufficient condition for passivity that relies on the Coulomb friction in the haptic device, as well as the encoder resolution. We experimentally verify our results with a one-degree-of-freedom haptic display, and find that the system can display nonpassive behavior in two decoupled modes that are predicted by the necessary and sufficient condition. One mode represents instability, while the other mode results in active tactile sensations.