共查询到20条相似文献,搜索用时 187 毫秒
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该文针对半挂式车辆的自主驾驶,设计一种基于迭代线性二次型调节器(iLQR)的轨迹跟踪控制器。通过深入研究转向过程中半挂式车辆的运动,建立满足非完整性约束的非线性车辆运动学模型,并根据期望轨迹对其进行线性化,得到线性的轨迹跟踪误差模型。基于扩展卡尔曼滤波器设计车辆状态观测器,估计车辆的航向角。通过对期望轨迹进行基于三次Bezier曲线的自适应拟合得到轨迹跟踪的前馈控制信息,并利用iLQR得到最优控制序列。基于Simulink进行半挂式车辆轨迹跟踪的仿真实验析,结果显示该控制器能够使半挂式车辆快速且稳定地跟踪期望轨迹,并且满足跟踪精度的要求。 相似文献
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提出了一种通过伸缩因子在线调节论域来优化机械臂轨迹跟踪控制的变论域模糊控制方法。首先设计了一种与关节角度偏差和偏差变化率动态加权相关的比例-指数混合型伸缩因子;然后,运用时间最优轨迹规划算法获取机械臂笛卡尔空间的期望关节轨迹;最后,基于所设计的变论域模糊控制器实现了一种三关节机械臂轨迹跟踪控制仿真,并分析了轨迹跟踪误差。仿真结果表明: 所设计的基于比例-指数混合型伸缩因子的变论域模糊控制器应用于机械臂轨迹跟踪的控制效果良好,具有响应速度快、无超调、稳态误差小的优点。 相似文献
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《振动与冲击》2017,(11)
讨论了载体位置、姿态均不受控情况下,存在外部扰动漂浮基两杆柔性空间机械臂的基于速度观测器的增广自适应运动控制与振动最优控制问题。选择合适的联体坐标系,利用Lagrange方法并结合动量守恒原理建立了飘浮基两杆柔性空间机械臂系统的动力学方程。利用奇异摄动法,将两杆柔性空间机械臂系统分解为一个关于载体姿态、关节轨迹跟踪的慢变子系统与一个描述柔性杆振动的快变子系统。以此为基础,提出了一个包含慢变控制项与快变控制项的复合控制器。利用自适应滑模观测器得到慢变子系统的观测速度向量,基于这个观测速度向量设计得到系统的增广自适应慢变控制律来实现关节轨迹的跟踪。利用线性观测器得到快变子系统的观测速度向量,基于这个观测速度向量并运用线性系统的最优控制理论得到了系统的快变控制律来实现柔性杆振动最优控制。系统的数值仿真证实了方法的有效性。该控制方案不需直接测量关节角速度、关节角加速度与柔性振动模态坐标导数以及漂浮基的位置、移动速度、移动加速度。 相似文献
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目的为提高包装机械手末端执行器轨迹跟踪精度,提出一种三维运动轨迹跟踪方法。方法获取拉绳式位移传感器在预先建立的三维坐标系中坐标数据和拉线长度。利用坐标和拉线长度计算运动物体的三维坐标数据,进而形成所述运动物体的三维运动轨迹。同时,给出基于ARM的轨迹跟踪控制器结构以及软件实现方法。结果实验结果表明,与传统示教盒相比,该方法可将定位精度提高1倍,相关误差可控制在0.3 mm以内。该方法在执行效率方面大约能够提升33%,提高了包装机械手的执行速度和分拣效率。结论所述轨迹跟踪方法能够提高包装机械手末端执行器的定位精度和定位速度,符合包装、食品、化工等行业的工艺要求。 相似文献
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研究了机器人焊接的控制.针对当前传统焊接工业机器人通常仅按照示教点进行既定轨迹运动,不能适应小批量多品种的柔性与智能生产线的问题,将工业相机、图像处理技术与智能机器人相结合,提取出焊缝轨迹发送给机器人,同时为提高机器人焊接过程中的轨迹跟踪精度问题,提出了一种基于模糊自适应PID焊缝轨迹跟踪的前瞻控制方法.在工程大型薄壁结构件的焊接过程中,该方法将视觉检测与识别用于焊缝轨迹跟踪,以提高焊接机器人的作业精度.最后通过实验,验证了该方法具有良好的自适应性和控制精度,能够实现前瞻偏差补偿控制. 相似文献
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P.C. Guan S.W. Chi J.S. Chen T.R. Slawson M.J. Roth 《International Journal of Impact Engineering》2011,38(12):1033-1047
Fragment-impact problems exhibit excessive material distortion and complex contact conditions that pose considerable challenges in mesh based numerical methods such as the finite element method (FEM). A semi-Lagrangian reproducing kernel particle method (RKPM) is proposed for fragment-impact modeling to alleviate mesh distortion difficulties associated with the Lagrangian FEM and to minimize the convective transport effect in the Eulerian or Arbitrary Lagrangian Eulerian FEM. A stabilized non-conforming nodal integration with boundary correction for the semi-Lagrangian RKPM is also proposed. Under the framework of semi-Lagrangian RKPM, a kernel contact algorithm is introduced to address multi-body contact. Stability analysis shows that temporal stability of the kernel contact algorithm is related to the velocity gradient between two contacting bodies. The performance of the proposed methods is examined by numerical simulation of penetration processes. 相似文献
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针对多通域封闭空间声场响应的亥姆霍兹方程的求解问题,本文基于核重构思想,应用无网格配点法构造近似函数,并利用最小二乘方法的原理解决边界问题,离散控制微分方程,建立求解的代数方程。边界问题以及稳定性问题一直是无网格法的难点,该方法的系数矩阵是对称正定的,因此结果具有较好的稳定性。通过数值算例分析多联通域二维问题中配点均匀分布与随机分布时此方法的精确性以及稳定性,利用典型算例对比无网格方法数值解与解析解,结果证明此方法不需要进行网格划分,节点可随机分布,精度较高且具有良好的收敛性。 相似文献
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Optimal-control theory is used in the manipulation planning for an ability-limited robot (i.e., a mobile robot with limited
maneuverability). The goal of manipulation is to push an object from a given initial configuration to a goal configuration—a
common task could be found in the application of mobile robots to manufacturing, in adaptive fixturing for robotic assembly
and in robotic gaming. The ability-limited robot is restricted here to perform only two types of motion in a plane. One is
pushing the object forward with a constant and fixed velocity, the other one is rotating the object counter-clockwise along
a fixed-radius circle with a constant angular velocity. First, the controllability of the proposed manipulation system is
proved. Then, the optimal-planning problem is studied within the framework of a switched system. By the aid of optimal-control
theory, it is proved that an optimal trajectory involves at most two switchings between these two simple actions. After evaluating
the existence and structure of the candidate optimal trajectories, an optimal planner is implemented to find the optimal trajectory.
Finally, manipulation examples are provided to demonstrate the proposed manipulation method. 相似文献
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Edouard Yreux Jiun‐Shyan Chen 《International journal for numerical methods in engineering》2017,109(7):1045-1064
Reproducing kernel particle method (RKPM) has been applied to many large deformation problems. RKPM relies on polynomial reproducing conditions to yield desired accuracy and convergence properties but requires appropriate kernel support coverage of neighboring nodes to ensure kernel stability. This kernel stability condition is difficult to achieve for problems with large particle motion such as the fragment‐impact processes that commonly exist in extreme events. A new reproducing kernel formulation with ‘quasi‐linear’ reproducing conditions is introduced. In this approach, the first‐order polynomial reproducing conditions are approximately enforced to yield a nonsingular moment matrix. With proper error control of the first‐order completeness, nearly second‐order convergence rate in L2 norm can be achieved while maintaining kernel stability. The effectiveness of this quasi‐linear RKPM formulation is demonstrated by modeling several extremely large deformation and fragment‐impact problems. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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《IEEE transactions on instrumentation and measurement》2008,57(9):1908-1917
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A quasi-convex reproducing kernel approximation is presented for Galerkin meshfree analysis. In the proposed meshfree scheme, the monomial reproducing conditions are relaxed to maximizing the positivity of the meshfree shape functions and the resulting shape functions are referred as the quasi-convex reproducing kernel shape functions. These quasi-convex meshfree shape functions are still established within the framework of the classical reproducing or consistency conditions, namely the shape functions have similar form as that of the conventional reproducing kernel shape functions. Thus this approach can be conveniently implemented in the standard reproducing kernel meshfree formulation without an overmuch increase of computational effort. Meanwhile, the present formulation enables a straightforward construction of arbitrary higher order shape functions. It is shown that the proposed method yields nearly positive shape functions in the interior problem domain, while in the boundary region the negative effect of the shape functions are also reduced compared with the original meshfree shape functions. Subsequently a Galerkin meshfree analysis is carried out by employing the proposed quasi-convex reproducing kernel shape functions. Numerical results reveal that the proposed method has more favorable accuracy than the conventional reproducing kernel meshfree method, especially for structural vibration analysis. 相似文献
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Maryam Mohammadi Reza Mokhtari Hamid Panahipour 《Engineering Analysis with Boundary Elements》2013,37(12):1642-1652
The paper introduces a Galerkin method in the reproducing kernel Hilbert space. It is implemented as a meshless method based on spatial trial spaces spanned by the Newton basis functions in the “native” Hilbert space of the reproducing kernel. For the time-dependent PDEs it leads to a system of ordinary differential equations. The method is used for solving the 2D nonlinear coupled Burgers' equations having Dirichlet and mixed boundary conditions. The numerical solutions for different values of Reynolds number (Re) are compared with analytical solutions as well as other numerical methods. It is shown that the proposed method is efficient, accurate and stable for flow with reasonably high Re in the case of Dirichlet boundary conditions. 相似文献
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ABSTRACTAs robot mission requirements become more complicated, it costs more and more time and energy to design and to debug a control system for robots. In this work, a method is proposed based on Petri nets (PNs) to shorten a program development cycle and to ease the reuse of programs. It consists of modeling a basic task by a task building block (TBB) so that functional codes can be masked into modules, constructing an executive PN (EPN) according to the logical relationship among a set of given tasks, and designing an executing program that can analyze and run an EPN. As a result, it costs less to design a credible control program for robots by this method. A robot control system of a mobile robot is designed to illustrate this method. 相似文献