为实现移动机器人在复杂动态障碍物环境中的避障,提出一种改进的快速随机扩展树(rapidly-exploring random tree,RRT^(*))与动态窗口法(dynamic window approach,DWA)相融合的动态路径规划方法。基于已知环境信息,利用改进RRT^(*)算法...为实现移动机器人在复杂动态障碍物环境中的避障,提出一种改进的快速随机扩展树(rapidly-exploring random tree,RRT^(*))与动态窗口法(dynamic window approach,DWA)相融合的动态路径规划方法。基于已知环境信息,利用改进RRT^(*)算法生成全局最优安全路径。通过消除RRT^(*)算法产生的危险节点,来确保全局路径的安全性;使用贪婪算法去除路径中的冗余节点,以缩短全局路径的长度。利用DWA算法跟踪改进RRT^(*)算法规划的最优路径。当全局路径上出现静态障碍物时,通过二次调整DWA算法评价函数的权重来避开障碍物并及时回归原路线;当环境中出现移动障碍物时,通过提前检测危险距离并转向加速的方式安全驶离该区域。仿真结果表明:该算法在复杂动态环境中运行时间短、路径成本小,与障碍物始终保持安全距离,确保在安全避开动态障碍物的同时,跟踪最优路径。展开更多
针对传统局部路径规划存在非全局最优、易陷入困境、导航效率低等问题,这里提出了一种将改进RRT(RapidlyExploring Random Trees)算法和动态窗口法融合的算法。首先优化基本RRT算法的采样策略,使用三次贝塞尔曲线平滑所生成的全局路径...针对传统局部路径规划存在非全局最优、易陷入困境、导航效率低等问题,这里提出了一种将改进RRT(RapidlyExploring Random Trees)算法和动态窗口法融合的算法。首先优化基本RRT算法的采样策略,使用三次贝塞尔曲线平滑所生成的全局路径。然后改进DWA(Dynamic Window Approach)算法的轨迹评价函数,构造路径最优的目标函数,以保证路径规划最优,从而提高移动机器人的避障性能。最后使用ROS(Robot Operating System)平台进行仿真验证,实验结果表明,与A^(*)-DWA和Dijkstra-DWA相比,所提出算法在复杂环境下路径长度更短、路径质量更优,行进时间明显减少,移动机器人的平均速度较A^(*)-DWA算法提高了约16.8%,证明了算法的有效性和实用性。展开更多
We construct recurrence plots(RPs)and conduct recurrence quantification analysis(RQA)to investigate the dynamic properties of the new Center for Financial Stability(CFS)Divisia monetary aggregates for the United State...We construct recurrence plots(RPs)and conduct recurrence quantification analysis(RQA)to investigate the dynamic properties of the new Center for Financial Stability(CFS)Divisia monetary aggregates for the United States.In this study,we use the lat-est vintage of Divisia aggregates,maintained within CFS.We use monthly data,from January 1967 to December 2020,which is a sample period that includes the extreme economic events of the 2007–2009 global financial crisis.We then make comparisons between narrow and broad Divisia money measures and find evidence of a nonlinear but reserved possible chaotic explanation of their origin.The application of RPs to broad Divisia monetary aggregates encompasses an additional drift structure around the global financial crisis in 2008.Applying the moving window RQA to the growth rates of narrow and broad Divisia monetary aggregates,we identify periods of changes in data-generating processes and associate such changes to monetary policy regimes and financial innovations that occurred during those times.展开更多
文摘为实现移动机器人在复杂动态障碍物环境中的避障,提出一种改进的快速随机扩展树(rapidly-exploring random tree,RRT^(*))与动态窗口法(dynamic window approach,DWA)相融合的动态路径规划方法。基于已知环境信息,利用改进RRT^(*)算法生成全局最优安全路径。通过消除RRT^(*)算法产生的危险节点,来确保全局路径的安全性;使用贪婪算法去除路径中的冗余节点,以缩短全局路径的长度。利用DWA算法跟踪改进RRT^(*)算法规划的最优路径。当全局路径上出现静态障碍物时,通过二次调整DWA算法评价函数的权重来避开障碍物并及时回归原路线;当环境中出现移动障碍物时,通过提前检测危险距离并转向加速的方式安全驶离该区域。仿真结果表明:该算法在复杂动态环境中运行时间短、路径成本小,与障碍物始终保持安全距离,确保在安全避开动态障碍物的同时,跟踪最优路径。
文摘We construct recurrence plots(RPs)and conduct recurrence quantification analysis(RQA)to investigate the dynamic properties of the new Center for Financial Stability(CFS)Divisia monetary aggregates for the United States.In this study,we use the lat-est vintage of Divisia aggregates,maintained within CFS.We use monthly data,from January 1967 to December 2020,which is a sample period that includes the extreme economic events of the 2007–2009 global financial crisis.We then make comparisons between narrow and broad Divisia money measures and find evidence of a nonlinear but reserved possible chaotic explanation of their origin.The application of RPs to broad Divisia monetary aggregates encompasses an additional drift structure around the global financial crisis in 2008.Applying the moving window RQA to the growth rates of narrow and broad Divisia monetary aggregates,we identify periods of changes in data-generating processes and associate such changes to monetary policy regimes and financial innovations that occurred during those times.