Sampling-based planning algorithms play an important role in high degree-of-freedom motion planning(MP)problems,in which rapidly-exploring random tree(RRT)and the faster bidirectional RRT(named RRT-Connect)algorithms ...Sampling-based planning algorithms play an important role in high degree-of-freedom motion planning(MP)problems,in which rapidly-exploring random tree(RRT)and the faster bidirectional RRT(named RRT-Connect)algorithms have achieved good results in many planning tasks.However,sampling-based methods have the inherent defect of having difficultly in solving planning problems with narrow passages.Therefore,several algorithms have been proposed to overcome these drawbacks.As one of the improved algorithms,Rapidlyexploring random vines(RRV)can achieve better results,but it may perform worse in cluttered environments and has a certain environmental selectivity.In this paper,we present a new improved planning method based on RRT-Connect and RRV,named adaptive RRT-Connect(ARRT-Connect),which deals well with the narrow passage environments while retaining the ability of RRT algorithms to plan paths in other environments.The proposed planner is shown to be adaptable to a variety of environments and can accomplish path planning in a short time.展开更多
Due to the interrelationship between the base placement of the manipulator and its operation object,it is significant to analyze the accessibility and workspace of manipulators for the optimization of their base locat...Due to the interrelationship between the base placement of the manipulator and its operation object,it is significant to analyze the accessibility and workspace of manipulators for the optimization of their base location.A new method is presented to optimize the base placement of manipulators through motion planning optimization and location optimization in the feasible area for manipulators.Firstly,research problems and contents are outlined.And then the feasible area for the manipulator base installation is discussed.Next,index depended on the joint movements and used to evaluate the kinematic performance of manipulators is defined.Although the mentioned indices in last section are regarded as the cost function of the latter,rapidly-exploring random tree(RRT) and rapidly-exploring random tree*(RRT*) algorithms are analyzed.And then,the proposed optimization method of manipulator base placement is studied by means of simulation research based on kinematic performance criteria.Finally,the conclusions could be proved effective from the simulation results.展开更多
The quality of hot-rolled steel strip is directly affected by the strip crown.Traditional machine learning models have shown limitations in accurately predicting the strip crown,particularly when dealing with imbalanc...The quality of hot-rolled steel strip is directly affected by the strip crown.Traditional machine learning models have shown limitations in accurately predicting the strip crown,particularly when dealing with imbalanced data.This limitation results in poor production quality and efficiency,leading to increased production costs.Thus,a novel strip crown prediction model that uses the Boruta and extremely randomized trees(Boruta-ERT)algorithms to address this issue was proposed.To improve the accuracy of our model,we utilized the synthetic minority over-sampling technique to balance the imbalance data sets.The Boruta-ERT prediction model was then used to select features and predict the strip crown.With the 2160 mm hot rolling production lines of a steel plant serving as the research object,the experimental results showed that 97.01% of prediction data have an absolute error of less than 8 lm.This level of accuracy met the control requirements for strip crown and demonstrated significant benefits for the improvement in production quality of steel strip.展开更多
To guide an unmanned aerial vehicle(UAV)flying in complex three-dimensional(3D)environments with unknown obstacles,a novel UAV path planning algorithm named IRRT∗-C2TD3 is proposed.The algorithm combines the rapidl...To guide an unmanned aerial vehicle(UAV)flying in complex three-dimensional(3D)environments with unknown obstacles,a novel UAV path planning algorithm named IRRT∗-C2TD3 is proposed.The algorithm combines the rapidly-exploring random tree star(RRT∗)algorithm with the twin delayed deep deterministic policy gradients(TD3)algorithm(a deep reinforcement learning algorithm).By employing exploration strategies from reinforcement learning,IRRT∗-C2TD3 improves the RRT∗algorithm.IRRT∗-C2TD3 is a two-stage path planning algorithm comprising pre-planning and real-time planning.It performs pre-planning of paths by generating paths based on geometric connections toward the goal and smoothing them using cubic B-spline curves.By designing the network architecture and reward function of the TD3 algorithm,real-time planning in unknown environments is achieved based on the pre-planned path from the first stage.Simulation results show that IRRT∗-C2TD3 demonstrates better path planning performance in 3D partially unknown environments than RRT∗-C2TD3,M-C2TD3 and MODRRT∗algorithms.展开更多
为提高果园自主移动机器人在山区、丘陵等复杂地形环境下运动路径规划效果,增强机器人野外工作性能,针对果园非结构化布局和起伏地形,本文提出了一种基于改进PF-RRT*(Plane fitting-rapidly exploring random trees star)算法的果园机...为提高果园自主移动机器人在山区、丘陵等复杂地形环境下运动路径规划效果,增强机器人野外工作性能,针对果园非结构化布局和起伏地形,本文提出了一种基于改进PF-RRT*(Plane fitting-rapidly exploring random trees star)算法的果园机器人路径规划方法。利用自适应采样步长策略,在果园不同障碍物密度环境下能够灵活地调节随机树扩展步长。采用自适应目标偏置的势场引导采样方法,能够有效引导随机树避开障碍物并向目标点扩展。此外,在随机树扩展过程引入地形评估函数。通过平面拟合技术对地形坡度、稀疏度和粗糙度进行综合评估,确保规划的路径在复杂地形中可通过性和安全性。最后,采用三次样条插值与高斯过程回归对路径进行平滑和优化。在仿真环境中,改进PF-RRT*算法与RRT*、Q-RRT*和PF-RRT*算法相比,轨迹偏差最多减少46.97%,路径长度最多减少7.64%,规划时间最多减少23.58%,且成功率和避障效果均优于对比算法。真实果园行间试验结果表明,与RRT*、Q-RRT*和PF-RRT*算法相比,改进PF-RRT*算法与理想轨迹偏差量减少34.04%、26.19%、27.91%、路径长度减少6.58%、3.16%和4.10%、规划时间减少30.56%、18.25%和33.52%。表明本文算法在果园复杂地形下能够实现自主移动机器人最优路径规划与导航。展开更多
针对异构多无人飞行器在障碍环境下的实时多类复杂任务规划问题,对任务分配模型的分布式求解方法进行研究。本文提出了一种改进的基于共识的捆绑算法(Consensus⁃based bundling algorithm,CBBA),重新设计任务包构建阶段的边际成本函数,...针对异构多无人飞行器在障碍环境下的实时多类复杂任务规划问题,对任务分配模型的分布式求解方法进行研究。本文提出了一种改进的基于共识的捆绑算法(Consensus⁃based bundling algorithm,CBBA),重新设计任务包构建阶段的边际成本函数,并基于快速扩展随机树星(Rapidly⁃exploring random tree star,RRT*)算法耦合路径规划成本计算,优化包构建时的任务选择操作,设计了一种局部按需选择通信优化的冲突消解机制,针对动态任务分配问题求解提出了一种局部任务路径集重构机制。仿真结果表明,在障碍环境下,改进算法的动态分配收敛时间减少38.1%,总得分增加15.1%,飞行总航程减少58.0%,且满足任务时序、时间窗口、飞行器资源限制以及动态任务添加等多重约束,实现了高效任务分配,具有较高的可行性和实时性。展开更多
为提升船舶与海洋工程水下作业的自主化水平,该文提出一种基于MB-Grasp模型的水下目标物抓取方法。首先通过搭载于作业平台的双目相机获取目标物RGB图像,再结合半全局立体匹配算法得到视差深度图;随后将RGB图像和深度图输入MB-Grasp网络...为提升船舶与海洋工程水下作业的自主化水平,该文提出一种基于MB-Grasp模型的水下目标物抓取方法。首先通过搭载于作业平台的双目相机获取目标物RGB图像,再结合半全局立体匹配算法得到视差深度图;随后将RGB图像和深度图输入MB-Grasp网络,估计目标物的位置、种类及抓取角,并通过坐标变换计算其在机械臂基坐标系下的位姿;最终利用RRT*(rapidly-exploring random tree star)算法进行路径规划,通过逆运动学求解各路径点关节角,经多项式插值生成关节空间平滑轨迹,驱动机械臂完成抓取。该研究搭建了模拟船舶水下作业环境的实验平台,成功实现了对模拟缆线和小型部件等目标的自主抓取,为船舶水下自主作业提供了可行方案。展开更多
为提升无线充电机库-无人机系统在城市环境中的安全性与效率,助力低空经济发展,开展该协同系统的时空路径规划研究。首先,结合中国无人机120 m飞行高度限制,建立包含30、60、90、120 m 4层的城市格栅化环境模型。其次,提出“全局粗规划...为提升无线充电机库-无人机系统在城市环境中的安全性与效率,助力低空经济发展,开展该协同系统的时空路径规划研究。首先,结合中国无人机120 m飞行高度限制,建立包含30、60、90、120 m 4层的城市格栅化环境模型。其次,提出“全局粗规划-局部细规划”的分层路径规划算法:全局层面运用改进A*算法完成机库节点间的路径优化;局部层面采用改进快速探索随机树(IRRT)算法实现城市密集建筑区域的精准避障。最后,融入时空规划机制,在空间上依据路径特性分配高度层以避免空域冲突,在时间上基于多阶段恒流(MCC)策略动态调控充电时间。仿真结果表明,所提动态充电方案较满充策略的总充电时间缩减55%,且分层路径规划算法可实现全局机库节点衔接与局部建筑避障的高效适配,高度分层模型能契合城市建筑分布与低空飞行法规要求。该研究验证了所提模型、算法,以及机制的有效性,解决了传统单一规划算法难以兼顾全局与局部、传统充电管理策略效率低的问题,为无线充电机库-无人机系统的实际应用提供支撑。展开更多
基金supported in part by the National Science Foundation of China(61976175,91648208)the Key Project of Natural Science Basic Research Plan in Shaanxi Province of China(2019JZ-05)。
摘要Sampling-based planning algorithms play an important role in high degree-of-freedom motion planning(MP)problems,in which rapidly-exploring random tree(RRT)and the faster bidirectional RRT(named RRT-Connect)algorithms have achieved good results in many planning tasks.However,sampling-based methods have the inherent defect of having difficultly in solving planning problems with narrow passages.Therefore,several algorithms have been proposed to overcome these drawbacks.As one of the improved algorithms,Rapidlyexploring random vines(RRV)can achieve better results,but it may perform worse in cluttered environments and has a certain environmental selectivity.In this paper,we present a new improved planning method based on RRT-Connect and RRV,named adaptive RRT-Connect(ARRT-Connect),which deals well with the narrow passage environments while retaining the ability of RRT algorithms to plan paths in other environments.The proposed planner is shown to be adaptable to a variety of environments and can accomplish path planning in a short time.
基金Supported by the National Science and Technology Support Program of China(No.2013BAK03B01)
摘要Due to the interrelationship between the base placement of the manipulator and its operation object,it is significant to analyze the accessibility and workspace of manipulators for the optimization of their base location.A new method is presented to optimize the base placement of manipulators through motion planning optimization and location optimization in the feasible area for manipulators.Firstly,research problems and contents are outlined.And then the feasible area for the manipulator base installation is discussed.Next,index depended on the joint movements and used to evaluate the kinematic performance of manipulators is defined.Although the mentioned indices in last section are regarded as the cost function of the latter,rapidly-exploring random tree(RRT) and rapidly-exploring random tree*(RRT*) algorithms are analyzed.And then,the proposed optimization method of manipulator base placement is studied by means of simulation research based on kinematic performance criteria.Finally,the conclusions could be proved effective from the simulation results.
基金supported by the National Natural Science Foundation of China(Grant Nos.52074085,U21A20117 and U21A20475)the Fundamental Research Funds for the Central Universities(Grant No.N2004010)the Liaoning Revitalization Talents Program(XLYC1907065).
摘要The quality of hot-rolled steel strip is directly affected by the strip crown.Traditional machine learning models have shown limitations in accurately predicting the strip crown,particularly when dealing with imbalanced data.This limitation results in poor production quality and efficiency,leading to increased production costs.Thus,a novel strip crown prediction model that uses the Boruta and extremely randomized trees(Boruta-ERT)algorithms to address this issue was proposed.To improve the accuracy of our model,we utilized the synthetic minority over-sampling technique to balance the imbalance data sets.The Boruta-ERT prediction model was then used to select features and predict the strip crown.With the 2160 mm hot rolling production lines of a steel plant serving as the research object,the experimental results showed that 97.01% of prediction data have an absolute error of less than 8 lm.This level of accuracy met the control requirements for strip crown and demonstrated significant benefits for the improvement in production quality of steel strip.
基金National Natural Science Foundation of China(No.62173084)Foundation of Shanghai Committee of Science and Technology,China(Nos.23ZR1401800 and 22JC1401403)。
摘要To guide an unmanned aerial vehicle(UAV)flying in complex three-dimensional(3D)environments with unknown obstacles,a novel UAV path planning algorithm named IRRT∗-C2TD3 is proposed.The algorithm combines the rapidly-exploring random tree star(RRT∗)algorithm with the twin delayed deep deterministic policy gradients(TD3)algorithm(a deep reinforcement learning algorithm).By employing exploration strategies from reinforcement learning,IRRT∗-C2TD3 improves the RRT∗algorithm.IRRT∗-C2TD3 is a two-stage path planning algorithm comprising pre-planning and real-time planning.It performs pre-planning of paths by generating paths based on geometric connections toward the goal and smoothing them using cubic B-spline curves.By designing the network architecture and reward function of the TD3 algorithm,real-time planning in unknown environments is achieved based on the pre-planned path from the first stage.Simulation results show that IRRT∗-C2TD3 demonstrates better path planning performance in 3D partially unknown environments than RRT∗-C2TD3,M-C2TD3 and MODRRT∗algorithms.
摘要为提高果园自主移动机器人在山区、丘陵等复杂地形环境下运动路径规划效果,增强机器人野外工作性能,针对果园非结构化布局和起伏地形,本文提出了一种基于改进PF-RRT*(Plane fitting-rapidly exploring random trees star)算法的果园机器人路径规划方法。利用自适应采样步长策略,在果园不同障碍物密度环境下能够灵活地调节随机树扩展步长。采用自适应目标偏置的势场引导采样方法,能够有效引导随机树避开障碍物并向目标点扩展。此外,在随机树扩展过程引入地形评估函数。通过平面拟合技术对地形坡度、稀疏度和粗糙度进行综合评估,确保规划的路径在复杂地形中可通过性和安全性。最后,采用三次样条插值与高斯过程回归对路径进行平滑和优化。在仿真环境中,改进PF-RRT*算法与RRT*、Q-RRT*和PF-RRT*算法相比,轨迹偏差最多减少46.97%,路径长度最多减少7.64%,规划时间最多减少23.58%,且成功率和避障效果均优于对比算法。真实果园行间试验结果表明,与RRT*、Q-RRT*和PF-RRT*算法相比,改进PF-RRT*算法与理想轨迹偏差量减少34.04%、26.19%、27.91%、路径长度减少6.58%、3.16%和4.10%、规划时间减少30.56%、18.25%和33.52%。表明本文算法在果园复杂地形下能够实现自主移动机器人最优路径规划与导航。
摘要针对异构多无人飞行器在障碍环境下的实时多类复杂任务规划问题,对任务分配模型的分布式求解方法进行研究。本文提出了一种改进的基于共识的捆绑算法(Consensus⁃based bundling algorithm,CBBA),重新设计任务包构建阶段的边际成本函数,并基于快速扩展随机树星(Rapidly⁃exploring random tree star,RRT*)算法耦合路径规划成本计算,优化包构建时的任务选择操作,设计了一种局部按需选择通信优化的冲突消解机制,针对动态任务分配问题求解提出了一种局部任务路径集重构机制。仿真结果表明,在障碍环境下,改进算法的动态分配收敛时间减少38.1%,总得分增加15.1%,飞行总航程减少58.0%,且满足任务时序、时间窗口、飞行器资源限制以及动态任务添加等多重约束,实现了高效任务分配,具有较高的可行性和实时性。
摘要为提升船舶与海洋工程水下作业的自主化水平,该文提出一种基于MB-Grasp模型的水下目标物抓取方法。首先通过搭载于作业平台的双目相机获取目标物RGB图像,再结合半全局立体匹配算法得到视差深度图;随后将RGB图像和深度图输入MB-Grasp网络,估计目标物的位置、种类及抓取角,并通过坐标变换计算其在机械臂基坐标系下的位姿;最终利用RRT*(rapidly-exploring random tree star)算法进行路径规划,通过逆运动学求解各路径点关节角,经多项式插值生成关节空间平滑轨迹,驱动机械臂完成抓取。该研究搭建了模拟船舶水下作业环境的实验平台,成功实现了对模拟缆线和小型部件等目标的自主抓取,为船舶水下自主作业提供了可行方案。
摘要为提升无线充电机库-无人机系统在城市环境中的安全性与效率,助力低空经济发展,开展该协同系统的时空路径规划研究。首先,结合中国无人机120 m飞行高度限制,建立包含30、60、90、120 m 4层的城市格栅化环境模型。其次,提出“全局粗规划-局部细规划”的分层路径规划算法:全局层面运用改进A*算法完成机库节点间的路径优化;局部层面采用改进快速探索随机树(IRRT)算法实现城市密集建筑区域的精准避障。最后,融入时空规划机制,在空间上依据路径特性分配高度层以避免空域冲突,在时间上基于多阶段恒流(MCC)策略动态调控充电时间。仿真结果表明,所提动态充电方案较满充策略的总充电时间缩减55%,且分层路径规划算法可实现全局机库节点衔接与局部建筑避障的高效适配,高度分层模型能契合城市建筑分布与低空飞行法规要求。该研究验证了所提模型、算法,以及机制的有效性,解决了传统单一规划算法难以兼顾全局与局部、传统充电管理策略效率低的问题,为无线充电机库-无人机系统的实际应用提供支撑。