UPR100弧焊机器人轨迹规划

对UPR100弧焊机器人进行了基于运动学的轨迹规划与仿真。采用D-H法建立了UPR100弧焊机器人运动学方程,运用Matlab编程实现了正、逆运动学求解,并利用正、逆运动学进行了轨迹规划。通过Matlab工具箱Sim Mechinics建立了UPR100弧焊机器人三维模型,并将轨迹规划仿真数据与理论数据进行比较,验证了轨迹规划的合理性与仿真模型的正确性,为UPR100弧焊机器人下一步的动力学研究与轨迹跟踪控制器设计奠定了理论基础。     

不同冲击度约束下智能汽车换道轨迹优化

这里研究在不同冲击度约束下智能汽车换道轨迹的优化问题.采用五次多项式作为车辆的换道轨迹模型,以自车速度、加速度以及冲击度为约束条件,兼顾车辆换道过程的安全性、舒适性和效率,用序列二次规划(SQP)算法对换道轨迹进行优化求解,得到最优换道运动轨迹;为研究冲击度约束设置对换道的影响,设计了换道轨迹求解的图形用户界面,根据换...     

基于指数增益迭代学习算法的机械臂轨迹跟踪

工业机器人是有着非线性、强耦合以及时变性等特点的复杂动力学系统。针对某公司的六自由度机器人的轨迹跟踪问题,利用拉格朗日法对机器人进行了动力学建模,并提出一种指数增益的迭代学习控制算法以对机器人进行轨迹跟踪,并分析了该方法的收敛性。利用MATLAB软件中的Simulink功能对机器人模型工作轨迹进行仿真,将结果与传统PD型迭代学习算法进行比较,证明了该控制算法的有效性与可用性。     

基于Matlab图像识别的Delta并联机械手连续轨迹规划

将Matlab图像处理技术与Delta并联机械手连续轨迹规划结合,并利用C#软件精确计算出连续轨迹中每个点的坐标,将这些坐标导入Pro/E软件中,成功模拟出了Delta并联机器人的连续运动,并采用Pro/E软件进行运动学、动力学分析。     

脱散的轨迹 对当代中国建筑师思考与实践发展脉络的另一种描述

文章尝试从部分20世纪50至70年代生当代中国建筑师实践策略和思考关注点的转变中寻觅线索轨迹。分析他们受到现代性话语体系的影响,同时检视他们在中国城市发展现状这一特定语境下的身份定义,进而尝试对当代中国建筑师思考与实践发展脉络进行描述。这一描述不从作品的结果出发作总结性的判断,而通过抽取不同建筑师的策略关注点和关键话语,进一步对贯穿不同时间段、没有因果关系的多重线索进行重新梳理和联结,对还原一个未曾明确的当代中国建筑话语体系给出研究建议。这一新的话语体系或许可以提供一种不同于西方现代性的"脱散的轨迹",从而见证多条线索在当代中国的某种不期而至的交汇或离散。     

PREDICTION OF PRESSURE BUILD UP IN A MICRO CAPILLARY DUE TO PARTICLE RETENTION

A single capillary model is proposed to predict the increase in pressure drop due to the particle deposition. The model is based on mass balance and trajectory analysis considering physical force (London—Van der Waals), hydrodynamic force (gravity and drag) and electrokinetic force (double layer). The validity of the model was tested experimentally by simulating a micro-capillary of radius 34.37 μm and circulating bentonite suspension at different flow rates and concentrations. The model is valid for predicting the pressure build up due to smooth deposition of particles with minimal surface energy.     

安全遮拦收放机械臂控制系统设计与实现

针对安全遮拦存在重量大,不易搬运等问题,设计了一款专门用于收放安全遮拦的新型机械臂.机械臂采用三个通用线性模组和一个旋转平台进行搭建,根据运动学模型,对机械臂进行轨迹规划,以PLC为控制核心,采用PTO模式控制步进电机,实现了机械臂的轨迹控制.实验结果表明:机械臂能准确将安全遮拦放置在指定位置,可实现多个安全遮拦的连续自动收放.     

A finite element model for analyzing horizontal well BHA behavior

Horizontal wells are proven to be better producers because they can be extended for a long distance in the pay zone. Engineers have the technical means to forecast the well productivity for a given horizontal length. However, experiences have shown that the actual production rate is often significantly less than that of forecasted. There are a number of reasons for the discrepancy of predicted to actual production rates in horizontal wells. However, it is a difficult task, if not impossible, to identify the real reason why a horizontal well is not producing what was forecasted. Often, the source of problem lies in the drilling of horizontal section such as permeability reduction in the pay zone due to mud invasion or snaky well patterns created during drilling. Although drillers aim to drill a constant inclination hole once in the pay zone, the more frequent outcome is a sinusoidal wellbore trajectory.Logging while drilling (LWD) and real time measurement of resistivity at bit help drill in the pay zone by constant monitoring of borehole trajectory and formation boundaries. Rotary steerable tools (RTS) allow spontaneous intervention to drilling direction and inclination if run with LWD tools. Nevertheless, there are still many cases where LWD cannot be deployed due to technical difficulties. One such case was noticed in the Middle East where LWD sensors were worn out completely during 1 h run time due to extreme formation abrasiveness. In the absence of LWD and RTS, it becomes a challenging task to drill a constant inclination borehole which will be addressed in this paper.The two factors, which play an important role in wellbore tortuosity, are the inclination and side force at bit. A constant inclination horizontal well can only be drilled if the bit face is maintained perpendicular to the longitudinal axis of bottom hole assembly (BHA) while keeping the side force nil at the bit. This approach assumes that there exists no formation force at bit. Hence, an appropriate BHA can be designed if bit side force and bit tilt are determined accurately.Finite element method (FEM) used in this study determines the bit side force and bit tilt simultaneously. The FEM is superior to existing analytical techniques because it can accommodate many more independent parameters which otherwise cannot be taken into account. As a matter of fact, it is believed that oversimplification of actual physical phenomena with unacceptable assumptions is the major source of error with existing BHA designs.This paper presents an FEM technique in assessing the bit tilt and side forces and compares the results with the existing techniques.     

空舰导弹弹道优化算法

本文对一般空舰导弹的纵向下滑段弹道优化设计进行了探讨;介绍了利用极小值原理解决优化的数值方法;以某空舰导弹为例对该弹道进行了计算,并得出了较满意的结果,可供该弹道的计算机辅助设计参考。     

Design, modeling and control of a hybrid machine system

A hybrid machine is such a machine where its drive system integrates two types of motors: the servomotor and the constant velocity (CV) motor. The existing research on the hybrid machine prototypes usually uses two servomotors, of which one “mimic” the CV motor by prescribing a constant velocity trajectory profile. It is obvious that this departs away from the real situation where a CV motor is in place. The CV motor will bring in the velocity fluctuation which can not be attenuated by the CV motor itself due to the lack of a control mechanism in the CV motor, yet be propagated to the servomotor, and further to the end-effector of the machine. The general strategy for controlling the hybrid machine is therefore to model this propagated fluctuation and incorporate it into a controller for the servomotor. A controller based on the sliding mode control technique is proposed for the hybrid machine in this paper. The stability analysis shows that the controller is asymptotically stable. Simulation with a preliminary test demonstrates the effectiveness and robustness of this controller. Finally, we examine further performance improvement through attaching a flywheel on the CV motor to demonstrate the effectiveness of the synergy of the integration of mechanical and electrical means.