In order to smooth the trajectory of a robot and reduce dwell time,a transition curve is introduced between two adjacent curves in three-dimensional space.G2 continuity is guaranteed to transit smoothly.To minimize th...In order to smooth the trajectory of a robot and reduce dwell time,a transition curve is introduced between two adjacent curves in three-dimensional space.G2 continuity is guaranteed to transit smoothly.To minimize the amount of calculation,cubic and quartic Bezier curves are both analyzed.Furthermore,the contour curve is characterized by a transition parameter which defines the distance to the corner of the deviation.How to define the transition points for different curves is presented.A general move command interface is defined for receiving the curve limitations and transition parameters.Then,how to calculate the control points of the cubic and quartic Bezier curves is analyzed and given.Different situations are discussed separately,including transition between two lines,transition between a line and a circle,and transition between two circles.Finally,the experiments are carried out on a six degree of freedom(DOF) industrial robot to validate the proposed method.Results of single transition and multiple transitions are presented.The trajectories in the joint space are also analyzed.The results indicate that the method achieves G2 continuity within the transition constraint and has good efficiency and adaptability.展开更多
We present a numerical method based on genetic algorithm combined with a fictitious domain method for a shape optimization problem governed by an elliptic equation with Dirichlet boundary condition. The technique of t...We present a numerical method based on genetic algorithm combined with a fictitious domain method for a shape optimization problem governed by an elliptic equation with Dirichlet boundary condition. The technique of the immersed boundary method is incorporated into the framework of the fictitious domain method for solving the state equations. Contrary to the conventional methods, our method does not make use of the finite element discretization with obstacle fitted meshes. It conduces to overcoming difficulties arising from re-meshing operations in the optimization process. The method can lead to a reduction in computational effort and is easily programmable. It is applied to a shape reconstruction problem in the airfoil design. Numerical experiments demonstrate the efficiency of the proposed approach.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
基金Supported by the National Natural Science Foundation of China(No.61573358)Research and Development of Large Multi-function Demolition Equipment in Disaster Site(No.2015BAK06B00)
文摘In order to smooth the trajectory of a robot and reduce dwell time,a transition curve is introduced between two adjacent curves in three-dimensional space.G2 continuity is guaranteed to transit smoothly.To minimize the amount of calculation,cubic and quartic Bezier curves are both analyzed.Furthermore,the contour curve is characterized by a transition parameter which defines the distance to the corner of the deviation.How to define the transition points for different curves is presented.A general move command interface is defined for receiving the curve limitations and transition parameters.Then,how to calculate the control points of the cubic and quartic Bezier curves is analyzed and given.Different situations are discussed separately,including transition between two lines,transition between a line and a circle,and transition between two circles.Finally,the experiments are carried out on a six degree of freedom(DOF) industrial robot to validate the proposed method.Results of single transition and multiple transitions are presented.The trajectories in the joint space are also analyzed.The results indicate that the method achieves G2 continuity within the transition constraint and has good efficiency and adaptability.
基金Supported by the Ministry of Research,Technology,and Higher Education Republic of Indonesia,through the Budget Implementation List(DIPA)of Diponegoro University,Grant No.DIPA-023.04.02.189185/2014,December 05,2013
文摘优化分析和计算液体动力学(CFD ) 同时被使用了，在哪个一个参量的模型在发现最佳的答案起一个重要作用。然而，与不规则的曲线为复杂形状创造一个参量的模型是困难的，例如一种海底的壳形式。在这研究，立方的 Bezier 曲线和曲线飞机交叉方法被用来产生考虑三个输入参数的一种参量的海底的壳形式的一个稳固的模型：鼻子半径，尾巴半径，和长度高度壳比率(L/H ) 。应用程序接口(API ) 脚本也被用来在 ANSYS 设计 modeler 写代码。结果证明海底的形状能与输入参数的某变化被产生。一个例子被给那显示出建议方法怎么能成功地被用于一个壳抵抗优化盒子。中间的海底的类型的参量的设计被选择被修改。首先，预先，原来的海底的模型用 CFD 被分析。然后，使用反应表面图，某候选人有一个最小的壳抵抗系数的最佳的图案被获得。进一步，在目标驱动的优化(GDO ) 的优化方法被实现与最小的壳抵抗系数发现海底的壳形式(C <sub> t </sub>) 。最小的 C <sub> t </sub> 被获得。在在起始的潜水艇和最佳潜水艇之间的 C <sub> t </sub> 价值的计算差别在 0.26% 附近，与起始的潜水艇和是的最佳潜水艇的 C <sub> t </sub> 0.001 508 26 和 0.001 504 29 分别地。结果证明最佳潜水艇壳形式显示出更高的鼻子半径(r <sub> n </sub>) 和更高的 L/H 起始的潜水艇比那些塑造，当时尾巴的半径(r <sub> t </sub>) 比起始的形状的小。
文摘We present a numerical method based on genetic algorithm combined with a fictitious domain method for a shape optimization problem governed by an elliptic equation with Dirichlet boundary condition. The technique of the immersed boundary method is incorporated into the framework of the fictitious domain method for solving the state equations. Contrary to the conventional methods, our method does not make use of the finite element discretization with obstacle fitted meshes. It conduces to overcoming difficulties arising from re-meshing operations in the optimization process. The method can lead to a reduction in computational effort and is easily programmable. It is applied to a shape reconstruction problem in the airfoil design. Numerical experiments demonstrate the efficiency of the proposed approach.
