基于凸面体圆弧航路的无人机自主避障算法

为解决无人机飞行过程中障碍物规避问题,提出一种新的三维自主避障算法.首先,根据障碍物的若干信息利用标准凸面体对不规则障碍物进行数学建模,用一个或多个标准凸面体覆盖障碍物整体或关键部分;然后,根据障碍物模型设计圆弧规避航路算法,将避障问题转化为跟踪规避航路控制问题,并定义避障判定、避障方向判断和成功避障规则;最后,结合非...     

基于LGMD的无人机避障方法研究

为提高无人机避障的灵活性和可靠性，提出了一种基于LGMD（Lobula Giant Movement Detector）的无人机避障方法，通过将视场分割为上、下、左、右4个方位，形成4个方位竞争的LGMD（C-LGMD），并利用Matlab软件进行算法实现和视频仿真分析，最后将算法移植到无人机硬件系统，开展悬停测试和实时飞行实验研究。由视频仿真分析和悬停测试结果表明，该算法能有效分辨来自不同方位的障碍物，具有较好的避障性能和鲁棒性；在实时飞行测试中，无人机在室内环境中可实现三维空间有效避障，验证了该算法的可靠性。研究结果为进一步探索无人机高效、可靠避障提供参考依据。     

A novel obstacle avoidance algorithm: “Follow the Gap Method”

In this paper, a novel obstacle avoidance method is designed and applied to an experimental autonomous ground vehicle system. The proposed method brings a new solution to the problem and has several advantages compared to previous methods. This novel algorithm is easy to tune and it takes into consideration the field of view and the nonholonomic constraints of the robot. Moreover the method does not have a local minimum problem and results in safer trajectories because of its inherent properties in the definition of the algorithm. The proposed algorithm is tested in simulations and after the observation of successful results, experimental tests are performed using static and dynamic obstacle scenarios. The experimental test platform is an autonomous ground vehicle with Ackermann steering geometry which brings nonholonomic constraints to the vehicle. Experimental results show that the task of obstacle avoidance can be achieved using the algorithm on the autonomous vehicle platform. The algorithm is very promising for application in mobile and industrial robotics where obstacle avoidance is a feature of the robotic system.     

On the design of an obstacle avoiding trajectory: Method and simulation

The paper suggests a new mathematical construction for the potential field used in the design of obstacle avoiding trajectories. The main benefits of the proposed construction are the quickness of minimum computation and the compensation for the main drawbacks specific to the “traditional approaches” belonging to the potential field method in general. The potential field definition and its minimum computation concept are presented. Next the concept is included in a design method for obstacle avoiding trajectories. The method is expressed in the form of an algorithm for obstacle avoidance. In the following step a state-space controller is designed in order to control the car along that trajectory. Digital simulation results obtained for the complete dynamic model of a car well validate the method.     

基于模糊控制的移动机器人避障研究

针对移动机器人在未知环境中的不确定性,利用Matlab构建了多传感器仿真试验移动平台,在Simulink中搭建移动机器人运动学模型,利用多传感器采集环境中的障碍物信息与目标物的方位角,设计了具有避障功能的模糊控制算法.通过模糊控制器控制移动机器人的左右轮速度实现机器人的转弯以及直走,根据机器人实时的角度反馈信息不断修正机器人的位姿以精确避障.仿真实验验证了该方法的可行性及有效性.     

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。     

冗余自由度机械手的避障控制

避障碍物一直是冗余自由度机械手的主要应用，本文采用伪逆矩阵法，以障碍物和 机械手之间的距离的函数作为性能指标函数来解冗余自由度机械手逆解，进行避障控制，并 提出一种简单的计算机械手和障碍物之间的距离方法，通过对一个三自由度的平面机械手进 行仿真，验证了算法的正确性．     

A hybrid estimation of distribution algorithm for simulation-based scheduling in a stochastic permutation flowshop

The permutation flowshop scheduling problem (PFSP) is NP-complete and tends to be more complicated when considering stochastic uncertainties in the real-world manufacturing environments. In this paper, a two-stage simulation-based hybrid estimation of distribution algorithm (TSSB-HEDA) is presented to schedule the permutation flowshop under stochastic processing times. To deal with processing time uncertainty, TSSB-HEDA evaluates candidate solutions using a novel two-stage simulation model (TSSM). This model first adopts the regression-based meta-modelling technique to determine a number of promising candidate solutions with less computation cost, and then uses a more accurate but time-consuming simulator to evaluate the performance of these selected ones. In addition, to avoid getting trapped into premature convergence, TSSB-HEDA employs both the probabilistic model of EDA and genetic operators of genetic algorithm (GA) to generate the offspring individuals. Enlightened by the weight training process of neural networks, a self-adaptive learning mechanism (SALM) is employed to dynamically adjust the ratio of offspring individuals generated by the probabilistic model. Computational experiments on Taillard’s benchmarks show that TSSB-HEDA is competitive in terms of both solution quality and computational performance.     

基于模拟退火高斯扰动的蝙蝠优化算法

蝙蝠算法（bat algorithm, BA）是一类新型的搜索全局最优解的随机优化技术。为了提高BA算法的搜索效果, 把模拟退火的思想引入到蝙蝠优化算法中, 并对蝙蝠算法的某些个体进行高斯扰动, 提出了一种基于模拟退火的高斯扰动蝙蝠优化算法（SAGBA）。分别将蝙蝠优化算法、模拟退火粒子群算法、SAGBA在20个典型的基准测试函数中进行仿真对比, 结果表明SAGBA不仅增加了全局收敛性, 而且在收敛速度和精度方面均优于其他两种算法。     

基于场景理解与改进型BUG算法的移动机器人避障

针对现有移动机器人在视觉避障上存在的局限,将深度学习算法和路径规划技术相结合,提出了一种基于深层卷积神经网络和改进Bug算法的机器人避障方法;该方法采用多任务深度卷积神经网络提取道路图像特征,实现图像分类和语义分割任务;其次,基于语义分割结果构建栅格地图,并将图像分类结果与改进的Bug算法相结合,搜索出最优避障路径;同时,为降低冗余计算,设计了特征对比结构来对避免对重复计算的特征信息,保障机器人在实际应用中实时性;通过实验结果表明,所提方法有效的平衡了多视觉任务的精度与效率,并能准确规划出安全的避障路径,辅助机器人完成导航避障。     

无人机反应式扰动流体路径规划

针对复杂三维障碍环境,提出一种基于深度强化学习的无人机(Unmanned aerial vehicles, UAV)反应式扰动流体路径规划架构.该架构以一种受约束扰动流体动态系统算法作为路径规划的基本方法,根据无人机与各障碍的相对状态以及障碍物类型,通过经深度确定性策略梯度算法训练得到的动作网络在线生成对应障碍的反应系数和方向系数,继而可计算相应的总和扰动矩阵并以此修正无人机的飞行路径,实现反应式避障.此外,还研究了与所提路径规划方法相适配的深度强化学习训练环境规范性建模方法.仿真结果表明,在路径质量大致相同的情况下,该方法在实时性方面明显优于基于预测控制的在线路径规划方法.     

基于贝叶斯估计与区域划分遍历的四轴飞行器避障路径规划算法

为了提高利用图像处理技术进行四轴飞行器避障的实时性,提出一种基于贝叶斯估计与区域划分遍历的避障路径规划算法.首先,通过贝叶斯估计来对四轴飞行器采集到的视频图像进行预处理;其次,对采集到的图像进行障碍物概率分析以获取视频图像中的关键帧,最大限度地提高四轴飞行器的实时性;最后,对选取的图像帧进行背景差分实现障碍物识别,并通...     

基于改进动态运动基元的6D轨迹规划

动态运动基元(DMPs)轨迹规划方法可以简化机械臂控制中参数调整的复杂过程,快速生成运动轨迹,但是面对姿态的流形特性以及跨零点情况,现有的DMPs很难达到预期的效果.本文提出了一种基于改进DMPs的笛卡尔空间6D轨迹规划方法.该方法采用四元数描述姿态,实现了位置轨迹与姿态轨迹的无奇异表示.通过解耦强迫函数与起–终点状态差值项之间的关联,消除了跨零点引起的轨迹抖动、无法生成与翻转等问题.此外,基于机械臂和障碍物间的距离与偏角建立了虚拟阻抗关系,并将其耦合到动力学模型中,实现了机械臂末端的避障控制,避免了避障行为过早问题,有利于减少消耗.机械臂6D轨迹规划仿真和实验表明,本文提出的改进DMPs方法有效.     

On-line Planning for Collision Avoidance on the Nominal Path

In this paper a solution to the obstacle avoidance problem for a mobile robot moving in the two-dimensional Cartesian plane is presented. The robot is modelled as a linear time-invariant dynamic system of finite size enclosed by a circle and the obstacles are modelled as circles travelling along rectilinear trajectories. This work deals with the avoidance problem when the obstacles move in known trajectories. The robot starts its journey on a nominal straight line path with a nominal velocity. When an obstacle is detected to be on a collision course with the robot, the robot must devise a plan to avoid the obstacle whilst minimising a cost index defined as the total sum squared of the magnitudes of the deviations of its velocity from the nominal velocity. The planning strategy adopted here is adjustment of the robot's velocity on the nominal path based on the time of collision between the robot and a moving obstacle, and determination of a desired final state such that its Euclidean distance from the nominal final state is minimal. Obstacle avoidance by deviation from the nominal path in deterministic and random environments is based on the work presented here and is investigated in another paper.     

两级传感器信息融合的移动机器人避障研究

针对移动机器人的避障问题,以AS-R移动机器人为研究平台,提出了一种将神经网络和模糊神经网络相结合的两级融合方法。采用BP神经网络对多超声波传感器信息进行融合,以减少传感器信息的不确定,提高对障碍物识别的准确率;采用模糊神经网络实现移动机器人的避障决策控制,使之更适合系统的避障要求。该方法使移动机器人在避障中具有较好的灵活性和鲁棒性。机器人避障实验验证了所提方法的有效性。     

A guaranteed obstacle avoidance guidance system

This paper presents a practical solution to the guidance of a unicycle type robot, including path following, obstacle avoidance and the respect of wheeled actuation saturation constraint, without planning procedure. These results are based on an extension of previous results on path following control including actuation saturation constraints. New solution for obstacle avoidance, with guaranteed performance, is proposed.     

未知环境下多AUV协同避障方法研究

针对多AUV（autonomous underwater vehicle）系统在未知环境中进行路径规划时难以兼顾避障与编队的问题,提出了一种基于领航—跟随者与行为的多AUV协同避障方法。首先,通过构造碰撞危险度及偏离目标评价函数,设计了AUV局部路径规划方法;在此基础上,结合编队控制方法,分别为领航者和跟随者设计不同的行为以及行为选择模式。半物理仿真实验结果表明,该算法能够实现多AUV系统在未知环境中的协同避障,且队形偏离度与恢复队形时间优于传统多机器人避障算法。实验结果证明了该算法的可行性与有效性。     

大数据支持下考虑障碍避让的机器人路径规划

为了使机器人在未知环境内可以成功规划出躲避障碍物的最短路径,在大数据支持下,设计了一种考虑障碍避让的机器人路径规划方法.首先分析机器人障碍物避让原理,确定机器人能够自由活动的范围.然后通过蚂蚁族群觅食流程对存在障碍物的路径进行模拟,获得基础路径规划结果,随后凭借赌轮盘规则细化,挑选节点通过机器人滚动窗口内映射,从而确定...     

Output‐feedback model predictive control for stochastic systems with multiplicative and additive uncertainty

This paper studies the output‐feedback model predictive control (MPC) design problem for linear systems with multiplicative and additive random uncertainty. We first present an off‐line optimization algorithm to optimize feedback gains of the observer and the dual‐mode control policy. After that, by defining a cuboid tube whose center and boundary are both time‐varying variables, we develop a set sequence with increased freedom to contain stochastic system trajectories. A quadratic performance function with analytic upper and lower bounds is minimized such that it decreases exponentially to a finite range under the expectation. The resulting MPC algorithms are proved to guarantee practically stochastic input‐to‐state stability. A numerical example of the wind turbine model illustrates the properties of the MPC algorithms.     

A model predictive obstacle avoidance method based on dynamic motion primitives and a Kalman filter

A dynamic motion primitive (DMP) is a robust framework that generates obstacle avoidance trajectories by introducing perturbative terms. The perturbative term is usually constructed with an artificial potential field (APF) method. Dynamic obstacle avoidance is rarely considered with this approach; furthermore, even when dynamic obstacles are considered, only the velocity and position information of the current state are incorporated into the obstacle avoidance framework. However, if the position of an obstacle changes suddenly, a robot may be placed in a dangerous position close to the obstacle, resulting in large obstacle avoidance accelerations, sharp trajectories, or even obstacle avoidance failure. Therefore, we present a model predictive obstacle avoidance method based on dynamic motion primitives and a Kalman filter. This method has three main components: Dynamic motion primitives are used to generate the desired trajectory and introduce perturbations to achieve obstacle avoidance; the Kalman filter method is adopted to estimate the future positions of the obstacles; and model predictive control is employed to optimize the repulsive force generated by the APF while minimizing the defined cost function, thus guaranteeing the safety and flexibility of the method. We validate the presented method with 2D and 3D obstacle avoidance simulations. The method is also verified with a real robot: the-Kinova MOVO. The simulation and experimental results show that the proposed method not only avoids dynamic obstacles but also tracks the desired trajectory more smoothly and precisely.