基于UR5苹果采摘机械臂的运动学分析及轨迹优化

随着苹果种植面积的不断扩大,传统的人力采摘方式已无法满足生产需求,为此,需积极推进苹果采摘机器人的研发与应用。传统的点对点运动控制会导致机械臂运动不平稳,严重影响采摘效率,因此,以UR5机械臂为研究对象,提出了利用标准D-H参数法解决UR5机械臂的正逆运动学问题,以关节最大速度为约束,结合五次多项式优化机械臂各关节轨迹,使各关节的轨迹平滑,实现机械臂的平稳运动。     

一种苹果采摘机器人关节伺服控制系统设计及仿真

当前,苹果采摘机器人大多选用工业机械臂,关节控制采用电机加减速装置来提高控制精度、增大驱动力矩,这无疑会增加系统的复杂性、成本以及降低系统控制性能;为改善这种情况,给出一种基于直流力矩电动机加谐波减速器的苹果采摘机器人关节控制方案,系统可大大减小驱动机构体积,提高系统刚性,实现低速稳定的精准控制;MATLAB环境下仿真结果表明,在0.5°和60°的阶跃给定下,系统超调量和稳态误差均为0;在幅值为5°,频率为3.14rad/s正弦信号输入下,系统输出能够完全跟随输入;系统控制精度达到了苹果采摘要求,为后续简化采摘机器人机械臂结构、甚至实现直接驱动提供了有力的理论支持。     

果树采摘机器人研制与设计

本文介绍研制一种果树采摘机器人。该机器人由移动底盘及机械手二部分组成,机械臂为PRRRP结构,采摘果实的末端操作器固连于机械臂上,末端操作器上安装视觉传感器、位置定位传感器、压力传感器和碰触传感器。操作器开合由气动控制,当操作器夹住果实后,由安装在操作器一侧的电动刀具切割果柄。硬件平台采用KP-6420i型工控机和台达交流伺服驱动器,视觉系统采用VFW图像采集系统。软件基于Visual C++6.0开发环境,采用基于径向基函数支持向量机的果实图像识别方法,可以满足果树采摘机器人对图像实时处理的速度要求,并通过串行通信实现对机械臂的运动控制。实验样机通过实验室和果园采摘实验,验证了设计的合理性和有效性。     

基于FuzzyP的多臂机器人机械臂控制系统设计

机械臂是多臂机器人的重要组成部分,针对基于姿态识别控制及位置识别控制系统受到被控量振荡影响,而导致机械臂运动轨迹控制不精准的问题,提出了基于FuzzyP的多臂机器人机械臂控制系统设计;基于FuzzyP控制系统,找到系统控制平衡点,设计系统硬件结构包含3个机械臂,共十八个自由度,简化关节控制器连线,选择直流有刷电机,采用增量型编码器,设计H桥电路,配合74ACT244增强驱动电路,利用NRF24L01无线模块获取与处理位置信息;使用FuzzyP控制器,抑制被控量振荡,控制连杆运动,完成多臂机器人机械臂控制方案设计;由实验结果可知,该系统轨迹与预期轨迹基本一致,较好解决多臂机器人机械臂对接精确定位要求。     

基于机器视觉的摘果机器人设计

文中针对果农摘果费事费力的问题,结合机器视觉、电机控制等技术的应用,设计了一种摘果机器人。该设计可以通过摄像头自动定位已经成熟的水果,并通过PID算法逐步靠近成熟的水果,再控制机械臂通过PID算法进行摘取,并将采摘的水果放到机器人的箱子中。以苹果为例,经过100次水果成熟度测试,识别成功率为100%;经过100次整机调试,成功摘取率达到了94%。调试结果表明,该设计具有很高的可靠性和实用性,可以代替人工采摘,实现了自动摘果功能。     

基于滑模控制器的双臂机器人控制仿真

针对工业机械臂运动控制中由于建模误差和未知干扰导致的控制误差问题,基于机器人力矩控制方法,采用滑模控制理论,利用关节角运动误差,设计并搭建机器人控制系统。以安川Motoman-SDA20机器人为例,对该机器人进行了运动学与动力学分析,搭建相关数学模型,并针对该机器人系统设计了滑模运动控制器。在机器人仿真环境VERP与Simulink中搭建联合仿真平台,对虚拟环境中的机械臂进行运动控制仿真试验,验证了算法的有效性。试验对比了逆运动学控制与滑模控制算法效果,同时对滑模控制算法在机械臂定点运动与轨迹跟踪中的控制效果进行了验证与分析。该控制算法计算过程简明、便于设计。利用VERP仿真平台,获得了更加直观的效果,实现了存在较大建模误差与较小控制频率下的机械臂位置控制,角度误差在0. 3 rad以内。该研究对于机器人控制算法的研究与仿真环境的搭建具有借鉴意义。     

开放分布式苹果采摘机器人控制系统研究及实现

针对以往采摘机器人多采用封闭集中式控制系统,缺乏通用性、可扩展性差和可靠性低等问题,在研制开发苹果采摘机器人控制系统的工作中,采用了开放分布式结构.根据苹果采摘机器人的机械结构及其运动特点,在硬件上选用工控机、伺服驱动器等设备,通信上采用结构简单、组网容易、造价低廉的RS-485网络,从而保证了系统的软硬件开放性,同时使得系统能够分布式控制,提高了机器人的安全性.此外,对系统的控制算法、软件也进行了设计,其中着重阐述了RS-485网络的通信协议和通讯方式.最后进行了通讯试验和苹果抓取试验,验证了系统的有效性.     

面向实时自避碰的双臂机器人力矩控制策略

为解决双臂机器人运动过程中的自碰撞问题，提出了一种面向实时自避碰的双臂机器人力矩控制策略。利用机械臂正向运动学构建双臂机器人动态骨架包围盒，用于简化计算关节间最小距离；根据机械臂关节空间阻抗控制规则，设计了基于关节间距离的力矩控制算法，将运动中各关节间距离转换为避碰力矩，并将避碰力矩和其他任务的期望力矩相加，从而得到控制双臂机器人运动的实际力矩。实验表明：当双臂机器人的设定杆件相互靠近且达到避碰距离时，本研究所提出的自避碰策略能够及时对机器人的运动关节产生一组平滑的避碰力矩，避免了机器人自身发生碰撞，验证了所提算法的有效性及实用性。     

基于细菌觅食算法的嵌入式机械臂角度控制器设计

进行机械臂角度控制器设计过程中,为提高机器人机械臂灵活性,降低关节角度控制误差,设计一种细菌觅食算法的嵌入式机械臂角度控制器。首先,构建机械臂动力学模型以获取机械臂的柔性特征及其关节位置,根据获取的信息确定角度控制器的硬件逻辑结构和算法。然后,使用ARM微处理器嵌入式操作系统,设计包含移动控制终端和机械臂控制端的控制器硬件结构。最后,采用细菌觅食算法优化控制器参数,并实现代码完成机器人机械臂角度的精准跟踪控制。仿真分析结果表明:所提方法具有较高的位姿跟踪精度、角度控制误差小、稳定性强,能够保证机械臂关节角度无超调,具有极高的机器工程应用价值。     

文献扫描机器人多关节机械臂滑膜控制系统设计

为提升机器人机械臂关节的传动性能,使其处于良好的反步自适应工作环境,设计文献扫描机器人多关节机械臂滑膜控制系统。利用关键控制电路,实现机械臂全局PID滑膜控制器与机器人多关节滑膜控制器间的定向连接,完成新型控制系统的硬件运行环境搭建。通过机器人控制传感器标定操作,建立等效控制及动态滑膜方程,并利用上述计算结果界定机械臂滑膜的动态品质,实现新型控制系统的软件运行环境搭建,结合软、硬件运行单元,完成文献扫描机器人多关节机械臂滑膜控制系统设计。模拟文献扫描机器人多关节机械臂运行状态,设计对比实验结果表明,与传统系统相比应用新型滑膜控制系统后,机械臂关节的传动能力得到有效提升,反步自适应参数最大值可达到1.70     

Robot accuracy and stiffness—An experimental study

Investigations in robotics have been mainly directed toward the design of robots with a significant degress of intelligence, capable of high adaptability. However, very little research has been done on the design of a robot manipulator as an executive mechanism of the intelligent control system, whose high quality design will allow the sophisticated functions imposed by the control system.

Experimental investigations of robot accuracy show unacceptable results which limit their future wider application. This is the reason why the off-life programming of robots has not been widely used, without which it is impossible to imagine a more significant integrationof robots in the CIM environment.

The object of our study has been to find out the causes of low degreee of robot accuracy, emphasizing the non-corresponding choice of the robot coordinate system, algorithmic and computational errors and drive and transmission element design. Comparison with corresponding results gained from investigations of CNC machine tools cannot be avoided because of the fact that robots are also machines from which accuracy is required. What is missing in robotics today, but which inevitably is required, is the establishment of a standard methodology for testing robot accuracy and other performance.     

农业机器人并联采摘臂视觉伺服控制

介绍了一种基于视觉伺服的农业机器人并联采摘系统,该系统由视觉系统、上位机、下位机、并联机构等4部分组成.视觉系统采集目标图像并传递给上位机,上位机对图像进行处理,识别和定位目标,计算并联机构的运动控制量,通过串口通信发送给下位机,下位机接收到控制量后,根据运动控制量驱动继电器模块作相应的开关动作,完成并联采摘臂的控制.实验证明:该系统对于实现农业机器人采摘作业具有可行性.     

基于自然语言的分拣机器人解析器技术研究

工业机器人通常采用特定的机器人语言进行示教编程与控制,对于操作人员需要具有较高专业与技能要求,并且示教周期长导致工作效率降低。为了提高工业机器人使用效率与易用性,提出一种基于受限自然语言解析器的设计方法。该系统通过对受限自然语言进行词法解析、语法解析、语义解析,得到所需求的工作意图,然后与实时生成的三维空间语义地图进行匹配,结合机械臂轨迹规划,生成能够完成工作任务的机器人作业程序,并完成了机器人作业程序的解析与实际机械臂的控制。通过实验证明设计的基于受限自然语言处理的分拣机器人解析器能够正确解析自然语言命令,实现对机械臂的控制。     

基于D-H参数的爬壁机器人吸附控制系统设计

传统爬壁机器人吸附参量存在同步不对称的问题,导致爬壁机器人吸附控制系统输出控制量精度降低,影响机器人整体控制效果;为了解决爬壁机器人吸附参量不对称问题,提出基于D-H参数的爬壁机器人吸附控制系统设计;基于D-H参数特点,设计系统总体框架,框架共分为硬件与软件两部分;硬件主要利用动态陀螺仪控制器控制处理指令数据,完成处理模块设计;通过无线控制遥感器KJ-F6000X-T6实现控制模块设计;软件部分采用与D-H参数相关的算法对控制程序进行设计;通过实验对比数据表明:提出设计系统具有同步爬壁机器人吸附参量对称性,单次控制量、双次控制量、多次控制量系数分别为0.7、0.6、0.5,符合控制系数标准范围,能够提升系统控制量输出精度。     

A framework for building mobile single and multi-robot applications

The complexity of robot software systems calls for the use of a well-conceived architecture together with programming tools to support it. One common feature of robot architectures is the modular decomposition of systems into simpler and largely independent components. These components implement primitive actions and report events about their state. The robot programming framework proposed here includes a tool (RoboGraph) to program and coordinate the activity (tasks) of these middleware modules. Project developers use the same task programming IDE (RoboGraph) on two different levels. The first is to program tasks that must be executed autonomously by one robot and the second is to program tasks that can include several robots and building elements.Tasks are described using a Signal Interpreted Petri Net (SIPN) editor and stored in an xml file. A dispatcher loads these files and executes the different Petri nets as needed. A monitor that shows the state of all the running nets is very useful for debugging and tracing purposes. The whole system has been used in several applications: A tour-guide robot (GuideBot), a multi-robot surveillance project (WatchBot) and a hospital food and laundry transportation system based on mobile robots.     

Virtual manipulator-based binocular stereo vision positioning system and errors modelling

There is a bottleneck of mobile robots positioning technologies for uncertain goals in complex field environment. Owing to the disturbance of the environment, the objects are hard to be located precisely by robot manipulator. Aiming at the positioning problem, binocular stereo vision system and positioning principle of the picking manipulator in virtual environment (VE) were proposed and expatiated upon; in addition, the manipulator positioning model was built in VE, and the manipulator positioning simulation system was developed by Microsoft Visual C++ 6.0; and the binocular stereo vision system platform with a three-coordinate guideway positioning was constructed for test; what’s more the error sources of vision positioning system was analyzed, and the camera system error was established; the mathematical model of experimental error and the camera calibration matching error were also found; with the developed robot manipulator positioning simulation software and vision system hardware, an experimental platform of positioning system was constructed, and using the platform, the stereo vision data was mapped to the manipulator and was guiding the accurate positioning in VE. Finally, experiment of positioning error compensation was carried out. Results of simulation in VE and the experiment showed that the vision positioning method was feasible for positioning in the field environment; it can be applied to control robot operation and to correct the positioning errors in real-time, especially to the long-range precision modelling and error compensation of robots.     

基于LLWin模块化语言与嵌入式设计的机器人控制系统设计

在工业机器人现代设计过程中,可以采用基于模型的嵌入式设计方法,进行机器人系统设计;在完成机器人总体方案设计后,用“慧鱼创意组合模型”拼装成机器人模型,采用LLWin模块化编程语言编制控制程序,对机器人进行控制,可以使机器人系统控制设计得到一个真实的验证,缩短设计周期,从而使控制系统设计优化。     

Enabling automated facility maintenance from articulated robot Collision-Free designs

Key challenges found in some facilities maintenance (FM) operations include the dependency on placing sophisticated workers in undesirable working conditions that could make them susceptible to accidents. Robot-assisted in-situ facilities maintenance represents new opportunities by assisting human operators when exposed to harsh environments. However, given the complexities and potential varieties of advanced robotic machinery available for use in facility maintenance workplaces in the future, there is still a legitimate risk of collisions between future robotic systems and the facility structure during the robot-assisted processes. This paper proposes and tests a simulation-based collision-free design method for future facilities that may be benefited from a robot-assisted FM process. At the most fundamental level, we consider interactions between the articulated manipulator (robot) and the surrounding facility structure. Inverse Kinematics (IK) and game engines are used to simulate the possible collisions between a given robot and the parameterized facility layout. To account for the uncertainty about the kinematic specifications of the future robotic machinery, a Monte Carlo method is used to model unique priority circumstances for each joint on the articulated manipulator. The simulation result, presented as the robot work zone envelope, is then used to estimate the collision probability given a certain design parameter, and the corresponding optimal design that balances the initial construction cost and the FM costs. The method is assessed for identifying a 3D spatial collision probability cloud within reach of a 7 DOF articulated manipulator that is marginally positioned within a pressure valve piping facility. These insights can provide future facility designers, managers, and equipment operators with a quick and flexible 3D spatial collision probability indicator to better design the facility and proximity limitations of any articulated manipulator positioned throughout a confined space for future robot-assisted FM processes.     

A control for spatial motions of a robot in a rectangular Cartesian coordinate system

Two mathematical models of a robot with elastic or rigid links working in a rectangular Cartesian coordinate system are proposed. The problems of dynamic and kinematic controls for such a robot are posed within the framework of the specified models. The difficulties of mathematical simulation of real robots of such a type with sliding joints are discussed in connection with the presence of elastic flexibility in the actuators. The technique for estimating the accuracy of positioning of the load carried by the robot based on joint use of the specified mathematical models is presented. As an example, solution of the problems of kinematic control of flexible and rigid robots with equivalent geometric and physical parameters functioning in a rectangular Cartesian coordinate system is considered.