装配路径规划中基于动态坐标的A*搜索算法

在装配路径规划中，最常用的方法是A^*搜索算法，通过两个实例说明在实体模型空间中，由于节点的扩展方向和运动方向不一致，导致A^*算法失败和算法复杂性的增加。在总结传统的A^*搜索算法的基础上，本文提出了动态坐标的A^*搜索算法。通过变换坐标，使节点扩展方向和运动方向始终保持一致，从而解决了由于节点扩展方向和被规划物体运动方向不一致所导致的算法失败。最后给出了变换坐标的原则，证明了动态坐标的A^*搜索算法的收敛性，并进行了复杂性分析。     

基于改进A^*势场法的机器人动态路径规划研究

针对人工势场法在路径规划中出现的目标点不可达、转折次数多及路线较长的问题,提出了一种动态环境下移动机器人全局路径规划的改进A^*势场算法。首先采用A^*算法在已知静态环境中进行全局最优路径规划,当移动机器人进入动态障碍物影响范围ρ0时,引入相对速度势场对人工势场法进行改进,进行局部动态路径规划,追踪沿A*路径运动的虚拟动态目标直至回到原路径,完成到达目标点的路径规划。将该算法与人工势场法通过MATLAB进行路径规划仿真比对,结果验证了该算法的可行性,并且有效减少了路径的震荡和累计转角,同时明显缩短了全局路径距离。     

融合改进A^(∗)算法与动态窗口法的机器人避障研究北大核心CSCD

针对机器人在全局未知环境的路径规划中无法进行实时动态避障的问题,提出一种将改进的A^(*)算法与动态窗口法融合的机器人避障方法。首先将传统A^(*)算法3×3搜索领域扩展至5×5搜索领域,并将16个搜索方向进行取舍至9个,同时优化启发函数,通过优化时间复杂度来提升A^(*)算法搜索效率;然后进行冗余节点移除操作,剔除机器人路径中的多余拐点和共线的点;改进后的A^(*)算法较传统A^(*)算法平均减少了65.805%的路径规划时间和4.967%的路径长度。最后将改进的A^(*)算法与动态窗口算法进行结合,使得机器人具有动态避障能力,且保证机器人在局部避障的过程中得到全局路径规划的最优解。     

用于无人车路径规划的改进A*算法

针对传统A*算法规划的路径存在路径长度较长、拐点数量较多和转折角度较大等问题,提出了一种用于无人车路径规划的改进A*算法.首先在传统A*算法的基础上考虑转弯成本并融入预判断规划策略,规划出一条初步路径;然后采用冗余拐点剔除策略优化初步路径,获得一种更优的无人车行驶路径.对传统A*算法、考虑转弯成本并融入预判断规划策略的A*算法和改进A*算法进行仿真对比.结果 表明:改进A*算法规划出的路径长度更短,拐点数量更少,转折角度更小,路径更加平滑.     

平滑ARA~*算法在智能车辆路径规划的应用

A~*算法是一种经典的启发式搜索算法,广泛应用于智能车辆的路径规划问题。但A~*算法效率低,不具有实时性。针对A~*算法的缺点,改进得到一种高效、实时的路径搜索算法ARA~*,ARA~*算法首先在一个松弛的约束条件下快速搜索到一条次优路径;然后在规划时间内逐渐加强约束条件,利用已搜索过的节点信息连续改进次优解,直到找到最优解或规划时间结束。其次,针对ARA~*算法得到的路径存在折线多、转折次数多等问题,对ARA~*算法得到的路径进行基于关键点的平滑处理。给出了平滑ARA~*算法流程,分析对比了各自的特点,通过栅格地图路径规划的MATLAB仿真结果验证了理论分析,同时仿真结果也说明平滑ARA~*算法的高效性、实时性。     

具备启发式路径优化的机械臂路径规划算法

在机器人的路径规划问题中,相较于基于搜索的算法和基于人工势场的算法,基于采样的路径规划算法能在高维状态空间中表现出良好的实时性。基于采样的路径规划算法对空间的探索通常是完全随机的,这不利于快速搜索路径。探讨了一种更高效的路径规划算法,用于帮助机器人在有障碍环境中完成避障作业。提出的Informed RRT^*SR(Informed RRT^*with Smart Rope)算法总体分为无碰路径的搜索和路径优化这两个步骤,路径搜索过程的算法实现与Informed RRT^*算法相同。通常,Informed RRT^*搜索得到的无碰路径是蜿蜒曲折的,结合路径优化算法能够进一步对路径进行优化,从而提高路径搜索效率。Informed RRT^*SR算法在路径优化过程中使用了启发式的路径探索规则,能够有效压缩搜索空间以提高搜索效率。机械臂的路径规划仿真实验结果表明,Informed RRT^*SR算法能够在相同时间内搜索到一条更便捷的路径,搜索得到的路径距离相较于Informe...     

基于A~*算法的空间机械臂避障路径规划

针对空间机械臂在轨操作任务需求,提出一种基于A*算法的避障路径规划算法。根据机械臂和障碍物几何特征,对机械臂模型和障碍模型进行简化。通过研究机械臂本身所固有的几何特性,根据障碍物的位姿坐标,分析机械臂各杆件与障碍物发生碰撞的条件,进而求解空间机械臂的无碰撞自由工作空间。在此基础上,利用A*算法在空间机械臂的自由工作空间进行无碰撞路径搜索,实现了空间机械臂的避障路径规划。通过仿真试验验证了基于A*算法的空间机械臂避障路径规划算法的有效性与可行性。     

基于改进A*算法的AGV路径研究

路径规划能力是AGV(Automated Guided Vehicle,自动导引运输车)系统智能化程度的体现。在众多算法中,A~*算法使用代价消耗估算方式达到较快的计算能力,被广泛应用于AGV的路径规划中,但仍存在局部最优的规划问题,规划的路径上存在冗余节点和较多不必要拐点。为减少运输路径中的总能耗,缩短路径总长度和减少AGV转弯次数,采用分裂和筛选的方案对传统A~*算法进一步优化,提出改进A~*算法,使其在实际工作环境中搜索更加迅速、考虑更加周密。在传统A~*算法基础上,在未知节点的启发函数里增加转弯权值,可以在计算规划过程中考虑转向所带来的消耗,从而减少转弯次数。使用任务分裂方案可以尽可能多地选择出较优路径,其中的最优解能够实现得转弯较少,展现出比较平滑的线路。基于Ubuntu下ROS系统版本进行仿真,对比实验结果表明,改进A~*算法在规划时间、总行程以及转弯消耗等方面都优于传统A~*算法,提升了AGV的实际运行效率,减少了AGV小车的耗能,可以缩短路径搜索规划时间,更符合工厂环境对AGV的需求。     

基于位置代价A*算法的机械臂避障路径规划

为了解决高维或复杂环境下A*算法路径规划寻路效率低、计算量大的问题,提出了位置代价A*算法,并将其应用于机械臂避障路径规划.首先在A*算法估价函数中加入节点位置代价,增加估价函数对节点位置优劣的判断;其次研究机械臂连杆的避障检测方法;在此基础上,将位置代价A*算法用于机械臂的避障路径规划.仿真试验表明,位置代价A*算法...     

一种五自由度机械手直线轨迹规划方法研究

针对一种有特定作业要求的五自由度机械手进行了轨迹规划研究。在运动学模型和工作空间的基础上,根据机械手末端的直线运动需求,不失一般性,设定所研究机械手的末端直线轨迹,分析了相应的轨迹规划的约束条件并建立约束方程。得到了在轨迹生成过程中各关节角和末端执行器作业中心的对应关系。详细分析了2种轨迹规划的算法,即多项式线性插值法和有界偏差关节路径法(BDJP)。并用这2种方法对机械手末端作业所需要的直线轨迹进行了仿真,给出仿真结果。     

空间机械手模型参数在轨标定方法研究

为了在轨辨识空间机械手真实模型参数,该文分析了模型参数误差来源,提出了基于遗传算法的空间机械手模型参数在轨标定方法,设计了关节变量误差和DH参数误差两组仿真数据对该方法进行验证。仿真结果表明,该方法切实可行,能够比较准确地识别出模型参数误差,有效地更新机械手运动学模型。与传统标定方法相比,基于智能优化算法的标定方法更具有广泛性。     

高速并联机械手动力学建模及计算力矩控制

基于模型的计算力矩控制由于考虑了非线性补偿而极大地提高了其控制品质。然而,并联机械手动力学模型的计算是非常耗时的,从而限制该控制器在工程中的应用。为此,针对2-DOF并联机械手Diamond 600,首先导出了机械手的位置、速度和加速度逆解模型,并根据动能定理独立计算出机械手的质量惯性矩阵,实现了控制算法解耦,然后利用虚功原理建立能用于实时控制的动力学简化模型。在此基础上,设计了适舍于并联机械手的计算力矩控制器。最后,将设计的控制器应用到2-DOF并联机械手,仿真和实验结果验证了算法的有效性和正确性。     

Stabilized multi-domain simulation algorithms and their application in simulation platform for forging manipulator

Most researches focused on the analytical stabilized algorithm for the modular simulation of single domain, e.g., pure mechanical systems. Only little work has been performed on the problem of multi-domain simulation stability influenced by algebraic loops. In this paper, the algebraic loop problem is studied by a composite simulation method to reveal the internal relationship between simulation stability and system topologies and simulation unit models. A stability criterion of multi-domain composite simulation is established, and two algebraic loop compensation algorithms are proposed using numerical iteration and approximate function in multi-domain simulation. The numerical stabilized algorithm is the Newton method for the solution of the set of nonlinear equations, and it is used here in simulation of the system composed of mechanical system and hydraulic system. The approximate stabilized algorithm is the construction of response surface for inputs and outputs of unknown unit model, and it is utilized here in simulation of the system composed of forging system, mechanical and hydraulic system. The effectiveness of the algorithms is verified by a case study of multi-domain simulation for forging system composed of thermoplastic deformation of workpieces, mechanical system and hydraulic system of a manipulator. The system dynamics simulation results show that curves of motion and force are continuous and convergent. This paper presents two algorithms, which are applied to virtual reality simulation of forging process in a simulation platform for a manipulator, and play a key role in simulation efficiency and stability.     

DIGITAL SIGNAL PROCESSING AND PARALLEL PROCESSING IN THE REAL-TIME SIMULATION OF A FLEXIBLE MANIPULATOR SYSTEM

This paper presents an investigation into the utilisation of digital signal processing and parallel processing techniques for the real-time simulation of a flexible manipulator system. A finite dimensional simulation of the system is developed using a finite difference approximation to the governing dynamic equation of the manipulator. The proposed algorithm allows dynamic modification of the boundary conditions and the inclusion of a distributed actuator and sensor term in the system dynamic equation. The algorithm developed is implemented on a number of uni-processor and multi-processor, homogeneous and heterogeneous parallel architectures. The partitioning and mapping of the algorithm on the homogeneous and heterogeneous architectures is also explored. A comparison of the results of these implementations in made and discussed to establish merits of design and real-time processing requirements in the control of flexible manipulator systems.     

基于遗传算法的机器人末端位置补偿轨迹规划

提出了一种机器人末端位置调整补偿的轨迹规划方法,利用遗传算法求解了机器人末端位置调整引起的关节变化量。利用该方法,机器人可在不精确环境下进行校正式示教学习,通过示教还原后可实现模糊环境中的机器人末端连续轨迹扫描。利用该方法在4自由度机器人上获取了理论关节轨迹与校正轨迹,试验结果证明了该方法的可行性。     

Implementation of a Robot System for Sculptured Surface Cutting. Part 2. Finish Machining

Rapid prototyping plays an important role in product development. There are two ways to realise rapid prototyping: one is to develop new prototyping equipment such as stereolithography apparatus (SLA), selective laser sintering (SLS), etc., and the other is to improve existing CNC techniques. In this work, a robot system for rapid prototyping, which is an enhancement of the CNC based method, is presented. A robot arm holding a milling tool is used to machine the prototype of a solid model drawn using a commercial CAD system. In a previous paper, Part 1, a strategy using the robot for rough machining was discussed and then an automatic tool-path generation method using a grid height array was presented. As a verification of the proposed algorithm, a number of prototypes were produced, which demonstrated the feasibility and advantages of the algorithm. In this paper, Part 2, an approach to represent C-space by incorporating possible variations in tooling orientations is proposed. In order to reduce the error on complex surfaces resulting from undercut or overcut operations, a curvature-matching algorithm is also developed. Finally, experimental work using collsion-free planning for manipulator movement and stimulation for the curvature matching algorithm is carried out.     

一种六自由度机械手的运动学分析

讨论了一种六自由度排爆机械手运动学问题,利用D-H坐标变换方法来建立了机械手的运动学数学模型和目标矩阵,利用MATLAB强大的符号运算功能,对方程进行求解,得出正逆运动学的解。通过正运动学的解,可以得出了解机械手各关节在执行任务时的运动轨迹;而逆运动学的解则可以求出机械手要到达某一位姿机械手各关节的扭角。运动学分析也为今后实现机械手的自动控制提供了设计参数。     

Computer-aided design of manipulation robots via multi-parameter optimization

In the paper are presented the basic ideas of computer-aided design of manipulation robots based on adopted optimizational criteria and on set constraints of strengths, as well as on actuator capabilities. Using complete models of manipulator dynamics, a simulation programme was derived, giving at its output the optimal design parameters of manipulator. An algorithm was formed, optimizing simultaneously two of the several significant manipulator parameters. In one case these are two diameters of circular cross-section segments, in another, one is a diameter and the other the reducing ratio of the DC motor type actuator.     

基于伪逆的冗余度机械臂关节速度约束方案

针对冗余度机械臂逆运动学求解结果可能超出机械臂物理限制的问题,提出两种基于伪逆算法的冗余度机械臂关节速度约束方案。首先,根据冗余度机械臂末端执行器的跟踪任务,运用伪逆算法在速度层上进行冗余度解析。其次,分别利用设计的两种约束方案对指定的关节速度进行限制与压缩,获得新的速度解并用以执行指定的轨迹跟踪任务。接着,针对末端执行器出现的位置误差,设计误差补偿函数以保证跟踪任务的顺利执行。最后,利用MATLAB软件对六自由度机械臂进行了运动规划仿真实验,并利用Arduino平台对六自由度机械臂进行算法实验验证。实验结果表明,两种约束方案下机械臂的最大跟踪误差均不超过3×10^-4 m,且时变函数约束方案在限制关节速度时获得更好的速度平稳性。     

Variable structure control of high-speed parallel manipulator considering the mechatronics coupling model

In this paper, a variable structure control strategy is adopted to improve position accuracy of Diamond 600k, a 2-Dof parallel manipulator. Firstly, mechanism and servomotor dynamics are developed in terms of the virtual work principle, while the mechantronics coupling model of the manipulator is formulated according to the equivalent torque. At this stage, the mass matrix of the mechanism is calculated individually to decouple the systematic model. This can effectively reduce the computational burden of the dynamic model in the real time control process. Then, various path-planning methods are compared with each other in order to explore which of them is more suitable to the high-speed manipulator. Last, results of the relevant experiments and simulations are presented from which it is easily can be seen that in comparison to conventional PID controller, the algorithm developed in this paper provides more reliable tracking performance.