基于快速动力学辨识的免外部传感器机器人碰撞检测

针对人机协作时机器人极有可能与人发生碰撞所导致的安全问题,提出一种基于动力学模型、无需要外部传感器的机器人碰撞检测方案.首先,根据对机器人低速下的动力学特性分析,采用逐次动力学辨识,在对机器人重力及摩擦力使用最小二乘法辨识后,运用Lasso对复杂的残余力矩进行辨识以获得简化模型,避免了复杂符号推导.然后,针对模型的不确定性,根据优化设计运动状态相关的动态阈值来处理残差的异常峰值.最后,以轻型工业机械臂为实验平台,让机器人执行作业轨迹与人类发生碰撞以验证碰撞检测算法.实验结果证明了碰撞检测方法的可行性和简单性,其能够实现对机器人快速动力学辨识,并可以实现灵敏准确碰撞检测,保证人机协作时操作人员的安全.     

基于ROS的多机械臂协同控制

随着21世纪医学技术发展,手术机器人已经成为近些年国内外机器人领域的一大热点,骨科1手术机器人更是其中的核心问题。为了解决目前骨科手术机器人中设备结构庞大、难以适用多场景复杂手术的问题,以六自由度机械臂作为研究对象,使用D-H法对机械臂进行数学建模;针对骨科手术的实际需求,使用ROS对单机械臂进行控制;使用串口通信原理,构建出基于包围盒碰撞检测算法和RRT路径规划算法的双机械臂防碰撞系统,并利用该系统完成基于主从协调的策略的跟踪任务。结果表明,该双机械臂防碰撞系统可以有效完成目标任务,这将为之后骨科手术机器人的协同控制研究提供平台。     

空间机器人目标捕获过程中碰撞运动分析

针对空间机器人目标捕获过程中的碰撞问题,提出了一种碰撞运动分析算法．基于空间机器人运动学 和动力学模型,利用碰撞过程中产生冲量的原理建立了碰撞动力学模型．针对具体的碰撞模型,利用空间解析几何 的方法进行了空间机器人与目标物之间的碰撞检测,设计了碰撞发生后机器人的运动分析算法．最后,通过仿真实 验验证了该算法的正确性和适用性．     

一种基于DTW-GMM的机器人多机械臂多任务协同策略

为了控制机器人完成复杂的多臂协作任务, 提出了一种基于动态时间规整?高斯混合模型(Dynamic time warping-Gaussian mixture model, DTW-GMM)的机器人多机械臂多任务协同策略. 首先, 针对机器人示教时轨迹时间长短往往存在较大差异的问题, 采用动态时间规整方法来统一时间的变化; 其次, 基于动态时间规整的多机械臂示教轨迹, 采用高斯混合模型对轨迹的特征进行提取, 并以某一机械臂的位置空间矢量作为查询向量, 基于高斯混合回归泛化输出其余机械臂的执行轨迹; 最后, 在Pepper仿人机器人平台上验证了所提出的多机械臂协同策略, 基于DTW-GMM算法控制机器人完成了双臂协作搬运任务和汉字轨迹的书写任务. 提出的基于DTW-GMM算法的多任务协同策略简单有效, 可以利用反馈信息实时协调各机械臂的任务, 在线生成平滑的协同轨迹, 控制机器人完成复杂的协作操作.     

基于DH标定的机器人正向运动学形式化验证

DH坐标系在机器人运动学分析中发挥着重要的作用。在基于DH坐标系构建的机器人控制系统中,机器人结构的复杂性使得构建安全的控制系统成为一个难题,仅仅依靠人工方法可能导致系统漏洞和安全风险,从而危及机器人的安全。形式化方法通过演绎推理与代码抽取实现了对软硬件系统的设计、开发及验证。基于此,本文设计了基于DH标定的机器人正向运动学的形式化验证框架。在Coq中构建了机器人运动理论的形式化证明,并验证控制算法的正确性以确保机器人的运动安全。首先,对DH坐标系进行形式化建模,构建相邻坐标系间转换矩阵的形式化定义,并验证了该转换矩阵与复合螺旋运动的等价性;其次,构建了机械臂正向运动学的形式化定义,并对机械臂运动的可分解性进行形式化验证;再次,本文对工业机器人中常见连杆结构及机器人进行形式化建模,并完成了正向运动学的形式化验证;最后,本文实现了Coq到OCaml的代码抽取,并对抽取的代码进行分析与验证。     

基于深度图像与三维栅格离线映射的机械臂环境建模方法

为确保动态非结构化环境中人、机器人、环境3者的安全,提出一种基于深度图像与三维栅格离线映射的机械臂环境建模方法,该方法分为离线映射与在线更新两个步骤.离线映射首先将机器人工作空间划分成三维栅格,然后利用标定得到的RGB-D相机内外参数矩阵离线计算深度图像与三维栅格之间的映射关系并保存;在线更新是利用帧差法和查询离线映射表的方式更新三维栅格中的环境信息.为全面描述机器人的工作空间,进一步扩展此方法,提出多传感器信息融合以及从环境模型中滤除机械臂本体的方法.整套环境建模方法具有描述能力强、模型精度一致、可实现多传感器信息融合以及可在线更新的优点.最后,分别通过仿真实验、基于两个Kinect相机和7自由度KUKA IIWA机械臂的实际建模与末端避障实验,验证所提出方法的有效性.     

多机械臂协调控制研究综述

多机械臂系统的协调控制是当今机器人领域的研究热点.针对机器人基坐标系标定,协调系统动力学建模,控制器综合方法等问题,介绍近年来多机械臂系统在协调控制上研究工作的进展,主要从系统的动力学模型建立方式和协调运动的控制综合方式两个方面进行深入介绍.全面系统地介绍多机械臂系统协调控制问题的研究现状与发展方向,并指明未来工作的研究方向.     

基于速度修正项的机械臂避障路径规划

针对机械臂运行过程中存在的碰撞问题, 提出一种基于速度修正项的机械臂避障路径规划方法. 利用B 样条曲线进行机械臂关节空间规划, 使机械臂能够在特定时刻运行到指定构型. 在运行过程中, 利用碰撞检测算法实时计算机械臂与障碍物的最小距离, 在碰撞即将发生时引入积分为零的避障速度修正项改变机械臂运行轨迹, 使得机械臂能够在实现障碍回避的同时, 保证其在特定时刻通过指定构型的要求. 仿真实验表明了所提出方法的正确性和有效性.     

基于空间代价地图的机械臂无碰撞运动规划

针对家庭服务机器人机械臂高安全性和低算法复杂度的两大需求,提出一种基于空间代价地图的机械臂运动规划新方法。利用空间代价地图来描述机械臂与约束条件发生冲突的可能性,以概率分析代替简单的布尔判断,提供了更合理的最优规划依据,从而实现更安全可靠的规划。同时将一个六自由度的规划问题降维为一个三自由度规划和一个四自由度规划的问题,在此基础上利用无需实时计算的先验碰撞数据代替实时的碰撞检测。利用该方法在ROS的rviz仿真平台上进行验证,结果表明该方法有效地提高了机械臂规划的安全性并降低了计算复杂度,有一定的实用价值。     

危险环境消防侦察机器人视轴规划算法研究

针对自主研发的危险环境消防侦察机器人展开研究。此机器人为履带式车身,装载一3自由度机械,高清侦察相机固定在机械臂末端。研究内容为在已知环境下自主规划机械臂规避障碍物,并调节相机视轴方向,实现对环境重点区域的锁定。首先对机械臂建立指数积（POE）正运动学模型,使用Minkowski和与三维凸包检测算法作为碰撞检测算法,使用蒙特卡洛方法在构型空间采样。再通过采样数据匹配末端视角方向,在末端建立虚拟连杆,使用碰撞检测算法保证实现视线无遮挡。仿真实验证明,使用此算法能够快速将相机视轴锁定至重点区域并保证无遮挡,且机械臂末端相机处于最佳位姿。     

Two robot arms in assembly by using impulsive information

When two robot arms execute coordinated motions in assembly, collision between the two end-effectors cannot be avoided. The collision effects on the two coordinating robots include two aspects: abrupt velocity changes of the robot joints and impulsive forces exerting on the contact point as well as on robot joints. Since the direction of the impulsive force exerting on the contact point is related to the relative position and orientation of the two mating parts, the impulsive force can be used to detect the alignment errors of the two end-effectors. Thus a new assembly method is proposed in this article. The new method uses impulsive information to adjust the position and orientation errors of the two robot arms in assembly, rather than employing a compliance mechanism. The advantage of the new method is that the jamming problem, which is usually associated with compliance methods, never takes place. To make the method practically useful, wrist force sensors are suggested to installed at the wrist of each robot. Dynamic relations between the sensed information and the impulsive force at the contact point are then established. The sensed information thus becomes useful in analyzing the alignment situation. Finally, practical cases are studied to illustrate the use of the new assembly method.     

六轴工业机器人先验引导RRT*避障轨迹算法研究

针对六轴工业机器人装配避障路径运动问题,研究了机器人整体避障运动路径规划方法,提出一种RRT*改进算法;算法以RRT*算法为基础,在障碍物建模中引入包围盒算法,加入对机器人各轴与障碍物的碰撞检测;在路径规划中加入对随机点生成方向与树枝生长方向的先验引导机制,优化了算法路径长度与路径搜寻效率;通过Matlab进行了试验验证,结果表明与标准RRT*算法相比,先验引导RRT*算法缩短路径长度14%左右,且满足机器人末端路径与手臂各轴的避障需求。     

Guaranteeing functional safety: design for provability and computer-aided verification

When autonomous robots begin to share the human living and working spaces, safety becomes paramount. It is legally required that the safety of such systems is ensured, e.g. by certification according to relevant standards such as IEC 61508. However, such safety considerations are usually not addressed in academic robotics. In this paper we report on one such successful endeavor, which is concerned with designing, implementing, and certifying a collision avoidance safety function for autonomous vehicles and static obstacles. The safety function calculates a safety zone for the vehicle, depending on its current motion, which is as large as required but as small as feasible, thus ensuring safety against collision with static obstacles. We outline the algorithm which was specifically designed with safety in mind, and present our verification methodology which is based on formal proof and verification using the theorem prover Isabelle. The implementation and our methodology have been certified for use in applications up to SIL 3 of IEC 61508 by a certification authority (TüV Süd Rail GmbH, Germany). Throughout, issues we recognized as being important for a successful application of formal methods in robotics are highlighted. Moreover, we argue that formal analysis deepens the understanding of the algorithm, and hence is valuable even outside the safety context.     

New Potential Functions with Random Force Algorithms Using Potential Field Method

Autonomous mobile robot path planning is a common topic for robotics and computational geometry. Many important results have been found, but a lot of issues are still veiled. This paper first describes new problem of symmetrically aligned robot-obstacle-goal (SAROG) when using potential field methods for mobile robot path planning. In addition, we consider constant robot speed for practical use. The SAROG and the constant speed involve two potential risks: robot-obstacle collision and local minima trap. For dealing with the two potential risks, we analyze the conditions of the collision and the local minima trap, and propose new potential functions and random force based algorithms. For the algorithm verification, we use WiRobot X80 with three ultrasonic range sensor modules.     

基于神经网络的机器人碰撞检测系统研究开发

要保证机器人本身具有比较高的健壮性、安全性和实用性,机器人必须具有碰撞检测功能,给出一种采用人工神经网络进行机器人碰撞检测的原理及实现方法.在分析机器人三轴多功能位置卡有关脉冲数据的基础上,总结机器人运动连续性的规律,并建立机器人碰撞检测问题的人工神经网络模型,设计并实现了相关的机器人碰撞检测算法及控制模块,最后介绍使用多线程方法,将碰撞检测模块加入到了机器人控制系统中.     

中医按摩机器人双臂推拿过程的避碰控制

讨论了中医按摩机器人的双臂协调运动控制问题.根据机械臂的结构特点,将空间避碰问题转化为平面内的避碰问题,对按摩机器人双臂推拿过程中可能发生的碰撞情况进行了分析.利用平面几何方法,对机器人双臂协调推拿过程进行了避碰规划,设计出一套双臂协调运动控制策略.利用MATLAB对双臂的避碰情况进行了运动学仿真,仿真结果表明本文中设计的方法可以有效的实现双臂在推拿过程中的协调运动.     

Extended linked voxel structure for point-to-mesh distance computation and its application to NC collision detection

When working with milling or polishing robots and large workpieces it is necessary to check not only the milling or polishing tool for collision, but it is also necessary to check the remaining arms of the robot for collision. In most of the cases the arms of the robot do not collide with the workpiece and so applying an existing collision detection algorithm to the arms of the robot slows the process down. In this paper, we present an algorithm for quickly assuring non-collisions, which is especially targeted at collisions of the arms of the robot with a workpiece. The algorithm is based on an extended voxel structure. More precisely, we extend a voxel structure by adding distance values to the corner of the voxels and by linking empty voxels to non-empty voxels to accelerate finding the desired voxel. This ensures that we only need to consider a small subset of the triangles describing the workpiece’s surface, namely those triangles that are close to the possible collision area. The triangles within each non-empty voxel are stored in a bsp-tree. For empty voxels, we save information about the distances to the mesh. This setup speeds up the point-to-mesh distance calculation, especially for points close to the mesh. The extra distance information in empty voxels enables a fast distance estimation and hence a fast early collision check.     

Decentralized adaptive coordinated control of multiple robot arms without using a force sensor

This paper presents a distributed adaptive coordinated control method for multiple robot arms grasping a common object. The cases of rigid contact and rolling contact are analyzed. In the proposed controller, the dynamic parameters of both object and robot arms are estimated adaptively. The desired motions of the robot arms are generated by an estimated object reference model. The control method requires only the measurements of the positions and velocities of the object and robot arms, but not the measurements of forces and moments at contact points. The asymptotic convergence of trajectory is proven by the Lyapunov-like Lemma. Experiments involving two robot arms handling a common object are shown.     

移动机器人3D仿真软件的设计与实现

在机器人技术研究中,为了提高机器人控制算法的开发效率,提出移动机器人三维仿真软件的设计方案并加以实现。该软件采用ODE物理引擎生成动力学世界和实现碰撞检测,提高了仿真速度和精确度,同时采用OpenGL绘制三维图形,改善了图形显示效果。仿真实例证明,该软件具有一定的实用价值。     

On the representation and collision detection of robots

In the proposed method, a robot is modeled as a union of three kinds of primitives, namely ellipsoids, spheres and convex polyhedrons. It will be shown that any primitive can be represented as a quadratic inequality or a set of inequalities with transform matrix included. Based on this method and with the addition of safety margins, various algorithms are developed for collision detection between two primitives. The collision detection problem of robots, in which each robot moves along a prescribed path, is then solved in a primitive versus primitive and off-line manner.