Interior-Point Methods Applied to the Predispatch Problem of a Hydroelectric System with Scheduled Line Manipulations

Transmission line manipulations in a power system are necessary for the execution of preventative or corrective main- tenance in a network, thus ensuring the stability of the system. In this study, primal-dual interior-point methods are used to minimize costs and losses in the generation and transmission of the predispatch active power flow in a hydroelectric system with previously scheduled line manipulations for preventative maintenance, over a period of twenty-four hours. The matrix structure of this problem and the modification that it imposes on the system is also broached in this study. From the computational standpoint, the effort required to solve a problem with or without line manipulations is similar, and the reasons for this are also discussed in this study. Computational results sustain our findings.

Extremum response surface method of reliability analysis on two-link flexible robot manipulator

In order to present a new method for analyzing the reliability of a two-link flexible robot manipulator,Lagrange dynamics differential equations of the two-link flexible robot manipulator were established by using the integrated modal method and the multi-body system dynamics method.By using the Monte Carlo method,the random sample values of the dynamic parameters were obtained and Lagrange dynamics differential equations were solved for each random sample value which revealed their displacement,speed and acceleration.On this basis,dynamic stresses and deformations were obtained.By taking the maximum values of the stresses and the deformations as output responses and the random sample values of dynamic parameters as input quantities,extremum response surface functions were established.A number of random samples were then obtained by using the Monte Carlo method and then the reliability was analyzed by using the extremum response surface method.The results show that the extremum response surface method is an efficient and fast reliability analysis method with high-accuracy for the two-link flexible robot manipulator.

NUMERICAL INVESTIGATION OF EFFECT OF ROLLING MANIPULATION OF TRADITIONAL CHINESE MEDICAL MASSAGE ON BLOOD FLOW

The hemodynamic mechanism of rolling manipulation (RM) of traditional Chinese medical massage (TCMM) is investigated. An axisymmetrical nonlinear model and an arbitrary Lagrangian-Eulerian finite element method (ALE-FEM) with rezoning algorithm were introduced to study the viscous flow through an axisymmetrical rigid tube with axially moving stenosis to simulate the rolling manipulation. Flow rate and wall shear stress were obtained by solving complete Navier-Stokes equations numerically. The numerical results show that the stenosis moving frequency, namely the frequency of rolling manipulation, has great effect on the disturbance of flow and the wall shear stress. The stenosis coefficient, which characterizes the severity of the stenosis, another adjustable parameter in rolling manipulation, also shows the significant effect on flow rate and wall shear stress. These numerical results may provide some data that can be taken into consideration when massage is used in clinic.

Optimal Trajectory of Underwater Manipulator Using Adjoint Variable Method for Reducing Drag

In order to decrease the fluid drag on an underwater robot manipulator, an optimal trajectory method based on the variational method is presented. By introducing the adjoint variables, which are Lagrange multipliers, we formulate a Lagrange function under certain constraints related to the target angle, target angular velocity, and dynamic equation of the robot manipulator. The state equation (the partial differentiation of the Lagrange function with respect to the state variables), adjoint equation (the partial differentiation of the Lagrange function with respect to the adjoint variables), and sensitivity equation (the partial differentiation of the Lagrange function with respect to torques) can be derived from the stationary conditions of the Lagrange function. Using the state equation, we can calculate the state variables (angles, angular velocities, and angular acceleration) at every time step in the forward time direction. These state variables are stored as data at every time step. Next, by using the adjoint equation, we can calculate the adjoint variables by using these state variables at every time step in the backward time direction. These adjoint variables are stored as data at every time step. Third, the sensitivity equation is calculated by using both the state variables and the adjoint variables. Finally, the optimal trajectory of the manipulator is obtained using the sensitivities. The proposed method is applied to the problem of two-link manipulators. It can obtain the optimal drag reduction trajectory of the manipulator under the constraints mentioned above.

Topology optimization design of the main structure of 6-DOF manipulator based on the variable density method

In order to solve the problems of too large mass,too complex structure and poor flexibility of the 6 DOF manipulator,the topological optimization theory based on variable density method is applied to the 6-DOF manipulator,the topology optimization of the main structural components of the manipulator is carried out with the help of the finite element software ANSYS,and the optimized structure is simplified according to the density distribution of the units and the requirements of manufacturability.the results are compared and analysed by static mechanics.It shows that the whole mass of the 6-DOF manipulator is reduced by 47.23%without changing the original mechanical properties after topological optimization,and the optimized model can meet the requirements of manufacturability,the optimization effect is signifcant,which can be used as a reference for the structure optimization of the 6-DOF manipulator.

基于卷积神经网络的采摘机械臂无碰撞运动规划研究

介绍了卷积神经网络的基本结构及其工作原理,基于DH参数法建立了采摘机械臂运动模型,并设计了一套采摘机械臂无碰撞运动规划算法,旨在实现对采摘机械臂的精确控制。MatLab仿真试验表明:采摘机械臂在系统的驱动控制下,能够准确从起点移动到目标点,轨迹比较圆滑,且能以最优的圆弧路径避开障碍物,优化效果明显,能够满足采摘机器人作业需求,证实了该算法的稳定性和可靠性。

面向稀疏奖励的机器人操作技能学习

基于深度强化学习的机器人操作技能学习成为研究热点,但由于任务的稀疏奖励性质,学习效率较低.本文提出了基于元学习的双经验池自适应软更新事后经验回放方法,并将其应用于稀疏奖励的机器人操作技能学习问题求解.首先,在软更新事后经验回放算法的基础上推导出可以提高算法效率的精简值函数,并加入温度自适应调整策略,动态调整温度参数以适应不同的任务环境;其次,结合元学习思想对经验回放进行分割,训练时动态调整选取真实采样数据和构建虚拟数的比例,提出了DAS-HER方法;然后,将DAS-HER算法应用到机器人操作技能学习中,构建了一个稀疏奖励环境下具有通用性的机器人操作技能学习框架;最后,在Mujoco下的Fetch和Hand环境中,进行了8项任务的对比实验,实验结果表明,无论是在训练效率还是在成功率方面,本文算法表现均优于其他算法.

基于六自由度机械臂的带电作业机械手模型设计研究

为满足高危环境下带电机器人的作业需求,避免机械臂在运动过程中出现抖动、失控等不良现象,提出基于六自由度机械臂的带电作业机械手模型。首先基于机械臂关节参数构建动力学模型,然后引入混合多项式插值法和粒子群算法对机械臂轨迹规划问题进行分析。实验结果表明,在粒子群优化算法下,机械臂4个关节的运行总时间分别为3.48、3.57、4.58和3.84 s,总运行时间最少缩短了10 s。在约束条件下,机械臂各关节始终处于安全范围内,不存在关节力矩大幅振荡情况。实验结果证实该带电作业机械手模型具有较好的应用效果。

“王氏五步法”手法整复治疗老年桡骨远端骨折临床观察

目的:观察“王氏五步法”手法整复治疗老年桡骨远端骨折的临床疗效。方法:选择老年桡骨远端骨折患者60例,采用随机数字表法分为观察组和对照组各30例,对照组行桡骨远端骨折切开复位解剖锁定型钛板内固定术,观察组采用“王氏五步法”手法整复。统计对比两组患者的手术时间、住院时间、疼痛评分、Cooney腕关节功能评分及桡骨高度,并评价两种治疗方法的安全性。所有患者随访3个月。结果:观察组住院时间、手术时间均短于对照组(P<0.05)。治疗后两组患者的疼痛评分均较治疗前降低(P<0.05),桡骨高度均升高(P<0.05)。组间比较,观察组术后半个月的疼痛评分低于对照组(P<0.05);术后半个月,两组桡骨高度比较,差异无统计学意义(P>0.05),术后一个半月、3个月对照组的桡骨高度优于观察组(P<0.05),观察组6例患者出现桡骨高度丢失;两组Cooney评分优良率比较,差异无统计学意义(P>0.05)。安全性方面,对照组发生1例术后感染、1例骨折延迟愈合,观察组未见并发症。结论:“王氏五步法”手法整复治疗老年桡骨远端骨折有利于骨折愈合及腕关节功能恢复,可有效避免开放手术的并发症;虽然术后影像学显示部分桡骨高度丢失,但并未影响患者腕关节功能恢复。

空间柔性机械臂建模、控制以及轨迹规划研究综述

经过几十年的不懈努力,中国航空航天技术日益突进,逐渐走向世界前列。但由于空间环境情况的复杂多变以及柔性臂本身固有的物理属性,常会导致末端执行器发生振动或未按规定路径运动等一系列问题。在简述国内外空间柔性机械臂发展现状的基础上,分析了空间柔性机械臂建模、控制方法以及轨迹规划3个方面的研究现状,并详细调研了相关内容在不同工况下适用的设计方法及其优缺点,以及部分专家学者对该方法的具体应用情况。最后结合上述分析内容,提出了柔性空间机械臂的发展趋势与展望。

FUZZY ADAPTIVE CONTROL OF FLEXIBLE-LINK ROBOT MANIPULATOR

A fuzzy adaptive control method is proposed for a flexible robot manipulator. Due to the structure characteristics of the flexible manipulator, the vibration modes must be controlled to realize the high-precision tip position. The Lagrangian principle is utilized to model the dynamic function of the single-degree flexible manipulator incorporating the assumed modes method. Simulation results of the fuzzy adaptive control method in the location control and the trajectory tracking with different tip disturbances are presented and compared with the results of the classic PD control. It shows that the controller can obtain the stable and robust performance.

基于OpenMV的五自由度机械臂控制方法研究

以五自由度机械臂为研究对象,建立D-H数学模型,探究几何法与代数法求关节角的过程,使用五次多项式插值的运动轨迹规划算法。通过建立仿真模型验证了运动学求解方法与轨迹规划算法的有效性。采用一种基于机械臂几何模型的逆运动学分析方法,设计OpenMV摄像头的图像识别与处理算法来精准定位目标物,并将目标物的位姿发送给主控系统,实现五自由度机械臂自主抓取目标物的功能。以乒乓球为抓取目标进行实验验证,结果表明:此设计能精准定位目标物,完成有效抓取,控制性能稳定、可靠。

Synthesis-temperature-dependent phase composition manipulation toward high thermoelectric performance in tetrahedrites

Tetrahedrite,an Earth-abundant natural mineral,has attracted extensive research interest because of its excellent thermoelectric performance.Herein,tetrahedrite samples comprising Cu-poor Cu_(12)Sb_(4)S_(13)and Cu-rich Cu_(14)Sb_(4)S_(13)phases have been synthesized using a colloidal method,in which the ratio of two phases is manipulated by controlling the synthesis temperature to improve the thermoelectric perfor-mance.It is found that an ultralow total thermal conductivity of∼0.3 W m^(−1)K^(−1)at 723 K is realized in the sample with a Cu-rich phase fraction of∼50%,which can be attributed to maximized phonon scattering by phase boundaries.As a result,combined with a decent power factor,this sample obtains an optimal zT of 1.15,which is about 85%higher than that of the sample with a Cu-rich phase fraction of∼64%and comparable to zT values of other eco-friendly,abundant Cu-based thermoelectric materials.This work demonstrates an effective synthesis-temperature-dependent phase composition manipulation strategy toward enhanced thermoelectric performance in tetrahedrites.

闭链级混联式液压机械臂运动控制方法

针对含有多个闭链结构的液压机械臂非线性强、控制精度低等特点,采用了虚拟分解控制方法消除了系统非线性引入的误差,以提高其控制精度。首先,根据驱动方式不同将整个机械臂分解为四类结构,针对每一类结构再将其虚拟分割成每一子系统,对每个子系统分别建立了刚体动力学模型、液压执行器流体动力学模型;然后,基于刚体动力学模型和流体动力学模型分别设计了刚性连杆控制律和液压执行器控制律,其前馈控制量和误差反馈量是高精度控制的基础;最后,使用Simulink的Simscape模块建立了该机械臂的多物理域混合模型,进行了轨迹跟踪效果验证,同时引入了控制性能指标,在不同机械臂的液压执行器空间进行了计算。研究结果表明:相比于比例-积分-微分控制器,基于虚拟分解控制理论搭建的控制器控制精度提升较大,单关节平均绝对误差最大降低了88.9%,且控制效果与其他较先进液压控制器的性能指标相近。针对含复杂闭链结构的混联式液压机械臂,采用虚拟分解控制理论能有效提升控制精度。

果园绿篱修剪机械手的设计与研究

为了解决果园绿篱修剪工具自动化程度低、修剪作业劳动强度大、工作效率低等问题,根据果园绿篱修剪作业要求,设计了一款实用的由液压驱动的四自由度修剪机械手,并确定了机械手各关节的运动范围。首先,基于标准的D-H参数法建立了机械手各连杆的坐标系,对机械手的正、逆运动学进行了求解;然后,利用MATLAB Robotics Toolbox建立了机械手运动学模型,对机械手正、逆运动学,机械手修剪绿篱顶面、侧面时各关节的运动轨迹,机械手各关节的角位移、角速度和角加速度曲线进行了仿真验证;之后,采用Monte Carlo法对机械手的工作空间进行了仿真分析,得到了机械手工作空间三维云图及平面云图;最后,试制实物样机进行了实验验证。研究结果表明:机械手正、逆运动学求解正确,所设计的机械手末端执行器完全能够到达所需修剪的目标位置。修剪机样机实验效果与预期相符,机械手工作时各关节运行平稳、修剪效率高、效果良好,能够满足对中、高绿篱自动修剪的要求,大大降低了修剪作业的劳动强度。

基于改进APF-RRT的6R机械臂避障路径规划

针对6R机械臂在复杂环境下进行避障路径规划时成功率低、效率低等问题,提出一种改进人工势场法(APF)与快速扩展随机树法(RRT)的融合算法。对于传统APF目标不可达问题,提出引入斥力调节因子优化斥力函数,使得机械臂靠近目标点时,障碍物对机械臂的斥力逐渐减小并顺利到达目标点;针对传统RRT算法随机性过强问题,提出目标导向策略进行优化,使得采样点有一定的概率向目标点扩展;当APF陷入局部最优时,采用改进RRT算法进行路径规划,当跳出局部最优时,切换为APF继续路径规划。仿真结果表明:改进APF-RRT算法能适应各种复杂环境,且相较于传统APF和RRT算法具有规划时间短、规划成功率高等优点,有效解决了APF目标不可达和局部最小值的问题。最后通过JAKA机器人实验平台进行实际环境实验,验证了改进APF-RRT融合算法的可行性。

基于碰撞检测的双机械臂避障路径规划

针对协同作业的双机械臂系统,提出一种不依赖于外部传感器和无需动力学建模的实时避障路径规划方法。基于运动学和混合包围盒法简化机械臂模型与障碍物,经投影相交法快速判断干涉的可能性,将碰撞检测转化为求解最短距离,再结合速度场以及添加虚拟约束点和考虑障碍物边界来改进传统人工势场法。最后,通过MATLAB-CoppeliaSim联合仿真验证包含静态和动态障碍物的碰撞检测算法。结果表明:该碰撞检测算法适应动、静两种复杂障碍物环境,通用性较高,生成的避障路径能够跳出极小值和实现目标可达,有效保障人机交互及设备的安全性。

抬高外旋牵引法治疗肩关节前脱位39例

目的探讨抬高外旋牵引法治疗肩关节脱位的效果。方法回顾性分析2018年1月-2022年10月在本院骨关节外科采用抬高外旋牵引法复位治疗肩关节脱位39例病例的临床资料,比较术前和术后2周疼痛程度、肩关节功能指数、复位成功率及并发症情况。结果39例在无麻醉情况下全部一次性复位成功,复查X线片显示肩关节均解剖复位,无医源性骨折,无血管神经损伤等不良情况,复位时间20 s~3 min,复位后疼痛VAS评分较复位前均明显降低,UCLA评分明显提高,差异具有统计学意义(P<0.05)。结论抬高外旋牵引法治疗肩关节前脱位一次性复位效果明显,复位后肩关节活动度正常,值得临床推广。

考虑激发充分性的机械臂动力学最小参数集辨识

在考虑粗大误差和随机误差情况下,为了提高机械臂系统动力学参数辨识的精确性和鲁棒性,文章提出了基于鲁棒粒子群算法的参数辨识方法,建立了机械臂动力学模型;筛选出了动力学最小参数集,用于消除动力学参数间的冗余性。为了实现参数充分激励,基于有穷傅里叶级数构造了激励轨迹,并以最小化矩阵条件数为目标实现了轨迹优化。为了提高参数辨识性能,在粒子群算法中引入了“向其他个体学习”的新型学习方式;在适应度函数设计中加入了粗大误差剔除功能,有效提高了算法的抗干扰能力。经机械臂系统加噪实验验证,鲁棒粒子群算法优化的驱动力矩残差均值为1.1975N·m,比量子粒子群算法减少了75.29%;力矩实际值与计算值相关度为0.9593,比量子粒子群算法提高了11.73%。实验结果表明,鲁棒粒子群算法在机械臂动力学参数辨识中具有更高的精度和更强的鲁棒性。

新型3PRPaR并联机器人的设计与多目标优化

设计一种三平移3PRPaR并联机器人机构。根据方位特征集证明机构输出特性,采用矢量法推导出位置逆解,根据运动轨迹仿真验证运动学模型正确性,分析机构奇异存在条件,并分别对工作空间与全局灵巧度等性能进行分析,以全域性能指标、可达工作空间指标、全域波动性能指标作为优化模型,采用NSGA-Ⅱ优化算法对3个目标函数进行多目标优化。研究表明,3PRPaR并联机器人具有较好的综合性能。