动态未知环境下基于相对坐标系的移动机器人实时运动规划

提出了一种简单、新颖的在动态未知环境下的移动机器人运动规划方法 .此方法基于相对坐标系 ,通过传感器信息实时调整机器人的行为来实现规划 .在规划过程中 ,机器人有两种行为 :向目标运动和避碰 ,且避碰行为具有优先权 .机器人两种行为的切换是基于加速度空间的 ,首先解决的是避碰问题 ,而向目标运动是作为避碰的反问题来考虑的 .仿真研究验证了此规划方法的有效性     

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.     

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．     

动态环境中基于模糊概念的机器人路径搜索方法

本文提出一种基于模糊概念的动态环境模型,以及在此模型基础上的机器人路径搜 索方法．这种方法利用动态环境中物体的运动信息进行局部搜索．通过计算机模拟实验,证 明这种方法在移动障碍和移动目标的环境中能有效的实现机器人避碰和导航．     

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。     

基于简化虚拟受力模型的群机器人多目标搜索协调控制

针对未知凸和非凸障碍物以及动态障碍物环境下群机器人多目标搜索问题,提出了一种基于简化虚拟受力分析模型的循障和避碰方法(SRSMT-SVF).对复杂环境下群机器人多目标搜索行为进行了分解并抽象出简化虚拟受力分析模型.基于此受力模型,设计了个体机器人协同搜索和漫游状态下的运动控制策略,使得机器人在搜索目标的同时能够实时避碰.通过对不同群体规模系统的仿真实验表明,本文控制方法能够使个体机器人在整个搜索过程中保持良好的避碰性能,有效地减少系统与环境之间和系统内部个体之间的碰撞冲突.相比于扩展粒子群算法(EPSO),本文方法使得搜索耗时和系统能耗至少减少了13.78%、11.96%,数值仿真结果验证了本文方法的有效性.     

基于时间栅格法和免疫算法的机器人动态路径规划

提出了一种机器人动态路径规划方法。该方法首先采用时间栅格法采标识动态障碍物。建立机器人的环境信息，然后使用免疫算法实现在动态环境下机器人的全局和局部路径规划，达到避障和避碰的目的。文中定义了免疫算法的多因素适应度函数由碰撞系数、距离、转角和安全系数决定。实验表明所提方法可以提高路径规划的效率，满足机器人实时导航要求。     

动态环境下机器人多目标路径规划蚂蚁算法

研究了一种新颖的动态复杂不确定环境下的机器人多目标路径规划蚂蚁算法。该方法首先根据蚂蚁觅食行为对多个目标点的组合进行优化,规划出一条最优的全局导航路径。在此基础上,机器人按照规划好的目标点访问顺序根据多蚂蚁协作局部路径算法完成局部路径的搜索。机器人每前进一步都实时地进行动态障碍物运动轨迹预测以及碰撞预测,并重新进行避碰局部路径规划。仿真结果表明,即使在障碍物非常复杂的地理环境,用该算法也能使机器人沿一条全局优化的路径安全避碰的遍历各个目标点,效果十分令人满意。     

基于改进人工势场法的足球机器人避碰控制

本文在分析足球机器人避碰的特点及传统人工势场法不足的基础上，提出了引入 障碍物的速度和加速度矢量的改进人工势场法，用于足球机器人的避碰控制．仿真实验表明 ，这种方法是可行的，并弥补了传统人工势场法的不足．     

基于约束的刚体碰撞响应仿真研究与应用

为了解决虚拟场景中刚体碰撞与穿透问题,采用了一种基于约束的碰撞响应方法。根据刚体之间的穿透深度和在碰撞点处的相对速度,判定不同的碰撞状态。通过将多刚体碰撞和多点碰撞分割为单个碰撞,以刚体在碰撞点相对速度法向分量构建法向约束,切向分量构建切向摩擦约束。根据不同的碰撞状态以及牛顿恢复系数碰撞模型求取法向误差,并以碰撞点相对速度切向分量作为切向摩擦误差。结合约束与误差,得到碰撞的约束方程,联合刚体的动力学方程,迭代求解,计算碰撞之后刚体的速度,更新刚体的坐标与姿态,并计算刚体顶点在世界坐标系中的坐标。在虚拟矿山场景中进行了应用,仿真效果较好。     

Trajectory time scaling of a mobile robot to avoid dynamic obstacles on the basis of the INLVO

To ensure the collision safety of mobile robots, the velocity of dynamic obstacles should be considered while planning the robot’s trajectory for high-speed navigation tasks. A planning scheme that computes the collision avoidance trajectory by assuming static obstacles may result in obstacle collisions owing to the relative velocities of dynamic obstacles. This article proposes a trajectory time-scaling scheme that considers the velocities of dynamic obstacles. The proposed inverse nonlinear velocity obstacle (INLVO) is used to compute the nonlinear velocity obstacle based on the known trajectory of the mobile robot. The INLVO can be used to obtain the boundary conditions required to avoid a dynamic obstacle. The simulation results showed that the proposed scheme can deal with typical collision states within a short period of time. The proposed scheme is advantageous because it can be applied to conventional trajectory planning schemes without high computational costs. In addition, the proposed scheme for avoiding dynamic obstacles can be used without an accurate prediction of the obstacle trajectories owing to the fast generation of the time-scaling trajectory.     

基于三维速度势场的AUV局部避碰研究

以势场方法的思想为出发点，提出一种基于速度势场的AUV局部避碰仿真方法．根据AUV的特点建立了空间碰撞危险区域和由水平面速度势场和垂直面速度势场组成的三维速度势场．该方法较好地利用了相对速度的信息．仿真实验证明此方法可以使AUV在水下多运动障碍物的环境中得到较好的局部避碰效果，为今后的海试打下了很好的基础．     

Reactive Path Planning in a Dynamic Environment

This paper deals with the problem of path planning in a dynamic environment, where the workspace is cluttered with unpredictably moving objects. The concept of the virtual plane is introduced and used to create reactive kinematic-based navigation laws. A virtual plane is an invertible transformation equivalent to the workspace, which is constructed by using a local observer. This results in important simplifications of the collision detection process. Based on the virtual plane, it is possible to determine the intervals of the linear velocity and the paths that lead to collisions with moving obstacles and then derive a dynamic window for the velocity and the orientation to navigate the robot safely. The speed of the robot and the orientation angle are controlled independently using simple collision cones and collision windows constructed from the virtual plane. The robot's path is controlled using kinematic-based navigation laws that depend on navigation parameters. These parameters are tuned in real time to adjust the path of the robot. Simulation is used to illustrate collision detection and path planning.      

Anticipated velocity based guidance strategy for wheeled mobile evader amidst stationary and moving obstacles in bounded environment

This paper is concerned with a class of pursuit‐evasion game problems amidst stationary and moving obstacles in a bounded environment. We concentrate on evader's strategy taking into account the following challenges: (i) pursuer and evader are nonholonomic wheeled mobile robots and the evader is slower than the pursuer; (ii) pursuer follows a proportional navigation law; and (iii) geometry of the environment is not known to the players, a priori. We propose an efficient evader‐centric anticipated velocity based guidance strategy. Pursuer's trajectory is anticipated at each step by the evader using quadratic polynomial interpolation. The aim of the evader is to escape interception with the pursuer for maximum possible time. To deal with static obstacles, a technique based on a well‐known tangent bug algorithm is presented. While dealing with dynamic obstacles, a recently introduced reciprocal orientation method is employed to avoid collision in situations when the dynamic obstacle also cooperates in the process. In case dynamic obstacles do not participate in the process of collision avoidance, a well‐known velocity obstacle method is employed for planning safe collision‐free paths. Efficiency of the proposed algorithms is analyzed with respect to the interception time and the distance traveled by the players. Copyright © 2014 John Wiley & Sons, Ltd.     

导线覆冰过程中水滴尺寸参数影响的碰撞率分析

导线覆冰增长预测中,碰撞率是一项不可忽视的重要参数,该参数的合理获取与实时环境参数如风速、水滴直径、温湿度、气压及导线直径等密切相关。水滴中值直径（MVD）常用来近似整个滴谱,但计算表明,对于不同体积百分比的水滴分布,基于MVD的碰撞率与实际滴谱碰撞率相差较大。论文提出了新的体积权重直径（VWD）来近似滴谱,分析三种水滴尺寸参数的碰撞率：基于VWD的碰撞率更接近实际滴谱的碰撞率,相对误差较小。解析了基于VWD的碰撞率精度更高的数学原理,讨论了该方法的适用范围。同时,通过试验的对比分析,计算碰撞率和实测碰撞率相对误差较小,覆冰质量接近,验证了该方法进行覆冰预测的可靠性,进一步将其应用于实际输电线路的覆冰厚度预测。     

Real-time Velocity Alteration Strategy for Collision-free Trajectory Planning of Two Articulated Robot Manipulators

Two articulated robots working in a shared workspace can be programmed by planning the tip trajectory of each robot independently. To account for collision avoidance between links, a real-time velocity alteration strategy based on fast and accurate collision detection is proposed in this paper to determine the step of next motion of slave (low priority) robot for collision-free trajectory planning of two robots with priorities. The effectiveness of the method depends largely on a newly developed method of accurate estimate of distance between links. By using the enclosing and enclosed ellipsoids representations of polyhedral models of links of robots, the minimum distance estimate and collision detection between the links can be performed more efficiently and accurately. The proposed strategy is implemented in an environment where the geometric paths of robots are pre-planned and the preprogrammed velocities are piecewise constant but adjustable. Under the control of the proposed strategy, the master robot always moves at a constant speed. The slave robot moves at the selected velocity, selected by a tradeoff between collision trend index and velocity reduction in one collision checking time, to keep moving as far as possible and as fast as possible while avoid possible collisions along the path. The collision trend index is a fusion of distance and relative velocity between links of two robots to reflect the possibility of collision at present and in the future. Graphic simulations of two PUMA560 robot arms working in common workspace but with independent goals are conducted. Simulations demonstrate the collision avoidance capability of the proposed approach as compared to the approach based on bounding volumes. It shows that advantage of our approach is less number of speed alterations required to react to potential collisions.