一种基于效益的多机器人避碰协调策略

多移动机器人系统在完成同时定位和地图构建SLAM任务时,机器人之间常常存在相互碰撞的问题,而这种碰撞的避免又不同于一般的避障,因为避障问题中的障碍物一般是不动的。为了解决机器人之间的避碰问题,提出了一种基于效益的多机器人避碰协调策略。该策略以提高多机器人系统探索效率为主,确定机器人通过交叉路口的顺序。同时考虑了动态协调避碰的情况,给出了确定机器人通过交叉路口顺序的算法。通过机器人在交叉路口实现避碰协调算法的仿真示例,对该方法的避碰协调过程进行了说明,并对仿真结果进行了分析,同时对仿真中机器人和目标位置的空间关系给出了合理的假设。     

基于初等运动的多机器人避碰及死锁预防

该文以一实际应用为背景提出了多移动机器人避碰及死锁预防算法,该算法将机器人的运行环境形式化地描述为初等运动集、冲突图、总任务集及机器人作业集,利用集合论、图论的有关方法及技术实现了多机器人间的避碰与死锁预防。当机器人的运行环境改变时,只需要对相应的集合描述文件进行修改,而不用对程序做任何屐改动。算法的另一个特点是利用避碰算法巧妙地完成了死锁预防。仿真和实际运行证明了该算法高效可靠。     

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.     

基于改进速度障碍法的多机器人避碰规划算法

针对多移动机器人运动协调中的动态安全避碰问题,在分析速度障碍法原理的基础上,设计用于机器人之间相互避让的互动速度法则,并通过制定机器人的碰撞时间、碰撞距离因子对构型障碍的大小进行实时调整,把运动障碍物、动力学约束下的多步可达窗口、目标点都映射到一种速度变化空间当中,使多机器人的动态避碰问题转化为一种最优化问题,并构造了新的优化评价函数;设计了基于改进速度障碍法的机器人动态避碰规划算法。仿真实验表明,该方法有效地克服了碰撞冲突,实现了多机器人之间的运动协调控制,提高了机器人追踪运动目标的快速性。     

基于人工协调场的多移动机器人实时协调避碰规划

为克服传统人工势场在动态未知环境下机器人避碰规划中存在的缺陷,提出人工协调场法(ACF).将场函数与机器人的风险状态相结合,给出并讨论了人工协调场的基本设计.基于人工协调场,考虑机器人的运动约束,实现了多机器人之间以及机器人与环境间的实时协调避碰,提出了一个多移动机器人无死锁实时避碰规划算法.理论分析和仿真试验证明所提方法的有效性.     

基于速度变化空间的移动机器人动态避碰规划

研究了移动机器人对运动障碍物的动态避碰．针对以往速度障碍法在动态避碰应用中存在的问题,制 订了相应的改进方法．综合考虑障碍物速度的动态变化和碰撞时间、碰撞距离,在速度变化空间中,基于避碰行为 动力学原理,设计了新的优化评价函数,采用双障碍物检测窗口进行动态避碰规划．仿真实验表明,该方法有效地 克服了避碰规划的保守性,提高了机器人运动的安全性,并能实现对运动目标的及时追踪．     

一种基于理性遗传算法(RGA)的协调运动行为合成算法

协调运动行为的合成是实现多机器人系统协调运动的关键.本文针对特定环境下的 多机器人协调运动问题,基于调速避碰的思想,借助CMAC神经网络,来描述各机器人的运动行 为与环境状态之间复杂的、非线性映射关系,利用理性遗传算法来合成与优化各机器人的运 动行为,从而实现多机器人已知环境下,运动行为的相互协调与优化.文章讨论了规划算法的 鲁棒性、完备性及时间复杂度.     

一种六自由度机械臂避障算法研究

文章首先分析了六自由度机械臂的特点,针对单个障碍物的避碰问题进行建模;接着设计了机器人避障的通用算法,利用该算法很好地解决了机器人的机械臂避碰问题,使机器人有效避障且完成任务.     

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。     

基于预测窗的轮式移动机器人最优避障避碰算法

针对非线性轮式移动机器人的避障以及多机器人间的相互避碰问题,提出了一种基于预测窗的避障避碰算法.首先为了便于预测碰撞的发生,通过反馈线性化将非线性的机器人运动学模型转化成线性模型;然后根据线性模型预测会导致机器人发生碰撞的所有相对虚拟加速度变化量集合,称之为加速度变化障碍.基于此,为每个机器人构造既能躲避障碍物又能相互避碰的可行加速度变化集合.然后通过优化指标函数求得最优虚拟加速度变化量,最后将其转换成机器人的实际控制量.这种算法与现有的相比,可使机器人在避障或避碰过程中的行驶方向角、线速度的变化幅值更小,角速度和线加速度的变化更为平顺,而且运行所用的平均时间更短.仿真结果演示了所提出算法的有效性和相对于已有方法的优势.     

A non-retraction path planning approach for extrusion-based additive manufacturing

Notwithstanding the widespread use and large number of advantages over traditional subtractive manufacturing techniques, the application of additive manufacturing technologies is currently limited by the undesirable fabricating efficiency, which has attracted attentions from a wide range of areas, such as fabrication method, material improvement, and algorithm optimization. As a critical step in the process planning of additive manufacturing, path planning plays a significant role in affecting the build time by means of determining the paths for the printing head's movement. So a novel path filling pattern for the deposition of extrusion–based additive manufacturing is developed in this paper, mainly to avoid the retraction during the deposition process, and hence the time moving along these retracting paths can be saved and the discontinuous deposition can be avoided as well. On the basis of analysis and discussion of the reason behind the occurrence of retraction in the deposition process, a path planning strategy called “go and back” is presented to avoid the retraction issue. The “go and back” strategy can be adopted to generate a continuous extruder path for simple areas with the start point being connected to the end point. So a sliced layer can be decomposed into several simple areas and the sub-paths for each area are generated based on the proposed strategy. All of these obtainable sub-paths can be connected into a continuous path with proper selection of the start point. By doing this, separated sub-paths are joined with each other to decrease the number of the startup and shutdown process for the extruder, which is beneficial for the enhancement of the deposition quality and the efficiency. Additionally, some methodologies are proposed to further optimize the generated non-retraction paths. At last, several cases are used to test and verify the developed methodology and the comparisons with conventional path filling patterns are conducted. The results show that the proposed approach can effectively reduce the retraction motions and is especially beneficial for the high efficient additive manufacturing without compromise on the part resistance.     

移动机器人编队的运动控制策略

为实现移动机器人编队的多样性、稳定性和队形变换连续性,并解决移动机器人编队运动中的避障、避碰、到达目标的问题,对基本队形进行分析,提出队形参数化的思路,建立基本队形虚结构的参数化数学模型,通过调整参数使队形在基本队形及其衍生的队形间进行变换;机器人在运行的过程中,利用行为融合方法、跟随领航者法、人工势场法和虚结构法对机器人进行运动控制,实现了机器人的避障、避碰、队形归建等目标。对上述策略进行了仿真实验,实验结果表明,使用本策略既保留了虚结构法队形稳定、队形归建迅速的优点,又改进了其灵活性差的不足。     

Two-stage Resampling for Bidirectional Path Tracing with Multiple Light Sub-paths

Recent advances in bidirectional path tracing (BPT) reveal that the use of multiple light sub-paths and the resampling of a small number of these can improve the efficiency of BPT. By increasing the number of pre-sampled light sub-paths, the possibility of generating light paths that provide large contributions can be better explored and this can alleviate the correlation of light paths due to the reuse of pre-sampled light sub-paths by all eye sub-paths. The increased number of pre-sampled light subpaths, however, also incurs a high computational cost. In this paper, we propose a two-stage resampling method for BPT to efficiently handle a large number of pre-sampled light sub-paths. We also derive a weighting function that can treat the changes in path probability due to the two-stage resampling. Our method can handle a two orders of magnitude larger number of presampled light sub-paths than previous methods in equal-time rendering, resulting in stable and better noise reduction than state-of-the-art methods.     

A Paradigm for Dynamic Coordination of Multiple Robots

In this paper, we present a paradigm for coordinating multiple robots in the execution of cooperative tasks. The basic idea in the paper is to assign to each robot in the team, a role that determines its actions during the cooperation. The robots dynamically assume and exchange roles in a synchronized manner in order to perform the task successfully, adapting to unexpected events in the environment. We model this mechanism using a hybrid systems framework and apply it in different cooperative tasks: cooperative manipulation and cooperative search and transportation. Simulations and real experiments demonstrating the effectiveness of the proposed paradigm are presented.     

Generation of feasible set points and control of a cable robot

Cable-suspended robots are structurally similar to parallel-actuated robots, but with the fundamental difference that cables can only pull the end-effector, but not push it. These input constraints make feedback control of cable-suspended robots a lot more challenging than their counterpart parallel-actuated robots. In this paper, we present a computationally efficient control design procedure for a cable robot with six cables, which is kinematically determined as long as all cables are in tension. The control strategy is based on dynamic aspects of statically feasible workspace. The basic idea suggested in this paper is to represent the reachable domain in terms of achievable set points under a specified control law that respects the input constraints. This computational framework is recursively used to find a set of reachable domains, using which, we are able to expand the region of feasibility by connecting adjacent domains through common points. The salient feature of the technique is that it is computationally efficient, or online implementable, for the control of a cable robot with positive input constraints. However, due to the complexity of the dynamics of general motion of a cable robot, we consider only translations. No cable interference is considered in this paper. Finally, the effectiveness of the proposed method is illustrated by numerical simulations and laboratory experiments on a six-degree-of-freedom cable-suspended robot.     

Communication based dynamic role allocation in a group of homogeneous robots

The field of collective robotics has been raising increasing interest in the last few years. In the vast majority of works devoted to collective robotics all interacting robots play always the same function, while less attention has been paid to groups of collaborating robots in which different robots play different roles. In this paper we evolve a population of homogeneous robots for dynamically allocating roles through communicative interactions. In particular, we focus on the development of a team of robots in which one and only one individual (the ’leader’) must differentiate its communicative behaviour from that of all the others (’non-leaders’). Evolved solutions prove to be very robust with respect to changes in the size of the group. Furthermore, both behavioural analyses and a comparison with a control condition in which robots are not allowed to move demonstrate the importance of co-adapting communicative and non-communicative behaviours, and, in particular, of being allowed to dynamically change the topology of communicative interactions. Finally, we show how the same method can be used for solving other kinds of role-allocation tasks. The general idea proposed in this paper might be used in the future for evolving general, robust, and scalable role differentiation mechanisms which can be exploited to develop non-communicative collaborative behaviours that require specialisation of roles within groups of homogeneous individuals.     

通用OCR开发工具的设计

提出了一个通用OCR开发工具的设想,用于各种文字的OCR软件的开发,它能够在使用者的干预下自动完成识别器的设计,大大减少文字识别软件开发的工作量。系统以决策树作为基本的判别器,并用多个决策树组成多方案识别系统。提出设计树和分类器设计器的概念,分别用于决策树设计过程的控制和决策树节点中的分类器的设计。最后实现一个实验系统,验证了该文的设想和设计方案的可行性。     

Drive based damping for robots with secondary encoders

Robot machining is a growing field due to the combination of large working envelope with relatively low investment and operating costs, compared to milling machine. Besides, the flexibility, which robot serial kinematics bring along, makes application of robot machining possible for different use cases. However, an occurring drawback of robot based machining systems is low stiffness compared to milling machines and, thus, poor accuracy and low eigenfrequencies with few damping. By that, robots for machining are prone to vibrations, resulting in poor machining results. In this paper the authors therefore present an approach for damping these vibrations, using state-of-the-art drives. Secondary encoders, which are increasingly available on industrial robots, are applied to detect these vibrations. This presented strategy has already been proven applicable on feed drives in milling machines and is now applied on industrial robots. To do so, the robot's vibrational behavior, like eigenfrequencies and eigenmodes, is examined in the whole workspace via measurements on real robots. Additionally the excitation by the milling process has been examined in relation to the occurring oscillations at the robot structure. The results of these research is adduced to estimate the applicability of this approach. Based on these results simulations are carried out to test the applicability of the damping strategy on industrial robots. As compliance of robots results mostly from gearboxes, simulation is carried out using a rigid-body-flexible-joint model. The simulations show that the dynamic behavior of the robots axes can be influenced in a positive way and vibration of the robots tool center point can be reduced significantly. Based on these findings, it is planned to implement this method on real hardware to perform tests, develop it further and optimize it.     

机器人双手协调运动中的误差分析及补偿

本文首次分析了机器人双手协调运动中的动态与控制误差,导出了误差矩阵方程,据此提出了补偿算法,实验验证了算法的有效性,由于本算法并不局限于某一特定类型的机器人,因而具有较普遍的意义。算法已应用于机器人双手协调运动的实时控制,文中并对误差引起的目标物体变形进行了讨论。     

梯度投影法应用于冗余机器人分解运动速度控制的新新方案

本文讨论分解运动速度控制框架下将梯度投影法应用于冗余机器人控制的有关问题。