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通过分析数控系统加工时常用的插补算法的特点,提出一种基于NURBS曲线的插补算法.该算法包括速度规划和实时插补两部分:速度规划部分考虑了工件加工时允许的最大轮廓误差,以保证高速运行过程中加速度的连续,使机床运行平稳,避免产生大的冲击;实时插补部分应用弦截法计算插补参数,能将实时插补产生的速度波动控制到理想水平,进一步减小了机床震颤.仿真实验结果表明,文中算法能够减小机床振动,实现高质量加工. 相似文献
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在分析机床最大速度、加速度和速度不连续点对实际加工的影响的基础上,设计了一种能够实现速度平滑过渡的NURBS实时插补算法.算法首先进行一次预插补,求出减速过程中超出机床最大加速度以及速度不连续的点,并采用逆求的方法求出减速点.然后在实时插补时根据求出的减速点进行速度规划.仿真实验结果表明,该插补算法能够在保证加工精度的前提下,以较高效率实现速度的平滑过渡. 相似文献
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在三维激光内雕机中,一方面,伺服进给速度很快;另一方面,各运动轴启停频繁。如不采用特殊方法来实现动态过程,必将给机床带来很大冲击。本文根据开放式结构控制思想,将加减速描述与系统数控程序相分离,从而实现一种柔性控制模式,保证在工作台运行平稳的前提下,达到以过渡过程时间最短为目标的加减速控制规律。 相似文献
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五坐标数控技术的联动原理 总被引:1,自引:0,他引:1
本文通过对五坐标数控技术的坐标运动规律进行分析研究,揭示了五坐标数控技术的联
动原理.即建立了从CAD中的理想轨迹的几何特性(包括位置、切矢、曲率)和五坐标联动的
运动动力学特性(包括位移、进给速度、各坐标理想速度和加速度)之间的通用数学模型.从
而可根据被加工零件表面的几何形状和机床的进给速度确定联动过程中各坐标的理想速度
和理想加速度. 相似文献
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为研究静脉采血机器人在针体植入过程中的NURBS曲线轨迹规划问题,以提高NURBS曲线的插补精度、系统运行过程中的平稳性为优化指标,提出了基于Simpson法的NURBS插补算法求解预估插补参数,并改进预估插补参数校正法来简化计算。采用基于正弦加速度曲线的NURBS插补速度规划方法并在法向加速度和弓高误差的共同约束下,控制插补速度并保证加速度连续。最后在设计的静脉采血机器人上用MATLAB进行仿真分析。结果表明,该算法简化了插补计算,降低了弓高误差,提高了插补精度,并有效控制了速度波动率,使运行平稳、运行轨迹连续平滑。 相似文献
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运动轨迹优化是工业机器人研究的一个重要领域.七段S型曲线是从传统的梯形加减速算法基础上发展而来的,尽管S型速度曲线控制算法提高了加减速过程中的稳定性,使运动过程中的速度变化连续,有较好的平滑性,但其加加速度仍存在阶跃变化问题,导致加速度存在明显的拐点,容易造成机器人在运动过程中发生冲击或振动.在上述研究的基础上,将多项式速度曲线控制算法与S型速度曲线控制算法相结合,提出了一种改进的S型速度曲线控制算法,通过优化加加速度,使其速度、加速度连续变化,曲线平滑性更好.在新代机械手臂控制系统下,对改进后S型速度曲线控制算法进行试验,证明所提出的算法在加减速过程中能够获得更加平滑的速度和加速度. 相似文献
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加减速控制是运动控制系统关键技术之一。加速度是不连续的线性加速和减速,它是影响运动控制系统的重要因素。加减速指数算法具有较强的跟踪能力,但在更高的速度时,稳定性会很弱。这个问题可以通过常规的S形曲线加减速的方法来解决,但S形曲线加减速太复杂。因此,提出了一种新的S曲线的加减速。提出的五个阶段S曲线加减速算法满足实际多轴运动控制器的要求。该算法有五个运动阶段:加加速阶段,减加速阶段,恒速阶段,加减速阶段和减减速阶段。在起点和终点的速度都是零,并且加加速度时绝对最大值J。分析表明:加速度曲线算法是一条连续的曲线,它表示时间和速度之间的连续关系,可以平稳的得到速度和加速度。 相似文献
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设计了一种基于STM32和LIS3DSH的高精度计步器.为了提高计步器的准确性,充分利用加速度传感器输出的三轴加速度信号,经数据预处理,采用动态阈值和峰值检测的改进算法.根据人体运动特征检测人体运动时加速度的变化,实现准确计步,并具备数据传输功能.实验结果表明,该计步器具有体积小、功耗低、精度高的特点. 相似文献
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D. A. Efimov A. V. Sumarokov S. N. Timakov 《Journal of Computer and Systems Sciences International》2012,51(5):732-741
The motion control about the center of mass of the communication satellite Yamal-200 is considered. Due to possible failure of the angular velocity sensors, an algorithm for maintaining a prescribed attitude without measuring the angular velocity was developed for this satellite. The algorithm ensures the gyroscopic stabilization of the satellite motion about the local vertical. In the course of control, the onboard computer stores projections of the flywheels?? angular momentum vector on the axes of the inertial basis; the control system tries to preserve the angular momentum magnitude and direction in the inertial space based on the measurements of the angular momentum. The workability of the proposed stabilization algorithm was confirmed by flight tests. 相似文献
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This work investigates how to distribute in an optimum fashion the desired movement of the end-effector of an industrial robot with respect to the workpiece, when there are redundant degrees of freedom, such as a positioning table. The desired motion is given as a series of acceleration functions in respective time intervals. The constraints of the optimisation are the available acceleration limit of axes, such as the table axes, the upper bounds to velocity and displacement of each axis and the avoidance of singular point areas of the robot, as defined by its manufacturer. The optimisation criterion is minimum total work for the motion. A genetic algorithm was used to solve the problem. The fitness function of the genetic algorithm calls a kinematics and dynamics simulation model of the robotic installation constructed in Matlab™, in order to compute the work consumed and to check possible violation of constraints. Examples of straight line and circular movement are given to prove the concept. Results are encouraging, yet demand on computing power is high. 相似文献
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A greedy algorithm for feedrate planning of CNC machines along curved tool paths with confined jerk 总被引:1,自引:0,他引:1
In this paper, the problem of optimal feedrate planning along a curved tool path for 3-axis CNC machines with the acceleration and jerk limits for each axis and the tangential velocity bound is addressed. It is proved that the optimal feedrate planning must be “Bang–Bang” or “Bang–Bang-Singular” control, that is, at least one of the axes reaches its acceleration or jerk bound, or the tangential velocity reaches its bound throughout the motion. As a consequence, the optimal parametric velocity can be expressed as a piecewise analytic function of the curve parameter u. The explicit formula for the velocity function when a jerk reaches its bound is given by solving a second-order differential equation. Under a “greedy rule”, an algorithm for optimal jerk confined feedrate planning is presented. Experiment results show that the new algorithm can be used to reduce the machining vibration and improve the machining quality. 相似文献
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《Robotics, IEEE Transactions on》2008,24(4):917-925
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如何有效地分析、监测突发人群异常状况已成为目前的一个研究热点问题。通过速度值的大小变化来分析是否出现异常状况是目前最常用的人群异常检测方法。但是,除了值的大小之外,运动的方向显然也是速度的另一个重要的特征。研究表明:人群出现异常时,一个最明显现象是人群的运动速度大小或运动方向突然出现变化,例如,由慢速行走转变为迅速奔跑、突然改变行进方向等异常运动。基于此,提出了基于加速度的人群异常检测算法。该算法采用金字塔Lucas-Kanade光流法,通过计算“帧平均加速度”对人群的运动进行分析。实验结果表明所提出的算法能够快速、有效地检测出人群运动的异常,而且相对于单纯运用运动速度值大小进行检测方法,检测结果更准确,应用范围更加广泛。 相似文献
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针对两轮驱动机器人运动模型定向误差的累积问题,提出改进的三轮驱动机器人运动模型,对EKF-SLAM算法的一致性进行改进;该模型通过对机器人车轮线速度的解耦运算,将机器人运动过程中的旋转角速度提取出来并作为系统的控制输入之一,从而可以直接得到各个控制时间间隔内的机器人姿态角变化,很好地避免了机器人定向误差的累积;最后,基于归一化估计方差的检验标准进行实验,验证了三轮驱动机器人运动模型有效提高了EKF-SLAM算法的一致性。 相似文献
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Image flow is the velocity field in the image plane caused by the motion of the observer, objects in the scene, or apparent motion, and can contain discontinuities due to object occlusion in the scene. An algorithm that can estimate the image flow velocity field when there are discontinuities due to occlusions is described. The constraint line clustering algorithm uses a statistical test to estimate the image flow velocity field in the presence of step discontinuities in the image irradiance or velocity field. Particular emphasis is placed on motion estimation and segmentation in situations such as random dot patterns where motion is the only cue to segmentation. Experimental results on a demanding synthetic test case and a real image are presented. A smoothing algorithm for improving the velocity field estimate is also described. The smoothing algorithm constructs a smooth estimate of the velocity field by approximating a surface between step discontinuities. It is noted that the velocity field estimate can be improved using surface reconstruction between velocity field boundaries 相似文献
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John L. Barron Allan D. Jepson John K. Tsotsos 《International Journal of Computer Vision》1990,5(3):239-269
This research addresses the problem of noise sensitivity inherent in motion and structure algorithms. The motion and structure paradigm is a two-step process. First, we measure image velocities and, perhaps, their spatial and temporal derivatives, are obtained from time-varying image intensity data and second, we use these data to compute the motion of a moving monocular observer in a stationary environment under perspective projection, relative to a single 3-D planar surface. The first contribution of this article is an algorithm that uses time-varying image velocity information to compute the observer's translation and rotation and the normalized surface gradient of the 3-D planar surface. The use of time-varying image velocity information is an important tool in obtaining a more robust motion and structure calculation. The second contribution of this article is an extensive error analysis of the motion and structure problem. Any motion and structure algorithm that uses image velocity information as its input should exhibit error sensitivity behavior compatible with the results reported here. We perform an average and worst case error analysis for four types of image velocity information: full and normal image velocities and full and normal sets of image velocity and its derivatives. (These derivatives are simply the coefficients of a truncated Taylor series expansion about some point in space and time.) The main issues we address here are: just how sensitive is a motion and structure computation in the presence of noisy input, or alternately, how accurate must our image velocity information be, how much and what type of input data is needed, and under what circumstances is motion and structure feasible? That is, when can we be sure that a motion and structure computation will produce usable results? We base our answers on a numerical error analysis we conduct for a large number of motions. 相似文献