On-line real-time path planning of mobile robots in dynamic uncertain environment

A new path planning method for mobile robots in globally unknown environment with moving obstacles is pre- sented. With an autoregressive (AR) model to predict the future positions of moving obstacles, and the predicted position taken as the next position of moving obstacles, a motion path in dynamic uncertain environment is planned by means of an on-line real-time path planning technique based on polar coordinates in which the desirable direction angle is taken into consideration as an optimization index. The effectiveness, feasibility, high stability, perfect performance of obstacle avoidance, real-time and optimization capability are demonstrated by simulation examples.

Study on path planning and compensation of off-line programming for thick walled curve welding

Thick walled curve welding are usually joined by multi-layer and multi-pass welding, which quality and efficiency could be improved by off-line programming of robot welding. However, the precision of off-line programming welding path was decreased due to the deviation between the off-line planned welding path and the actual welding path. A path planning algorithm and a path compensation algorithm of multi-layer and multi-pass curve welding seam for off-line programming of robot welding are developed in this paper. Experimental results show that the robot off-line programming improves the welding efftcieney and precision for thick walled curve welding seam.

Path Planning of Planar Kinked Line Seam by Visual Servoing for Robotic Welding

Welding path planning can substitute for the manual teaching process of the robot and can promote the autonomous level of the robotic welding. A path planning method by visual servoing was presented, in which the optimal angle of charge-coupled device (CCD) camera was also planned. Aiming at planning two forms of kinked line seams, obtuse angle seam and right angle seam, a practicable solution was put forward. In this solution, the intersection of two adjacent straight segments is detected in each local seam image, and if intersection is found, the seam errors are calculated using the next straight segment. The experimental results show that kinked line seam can be well planned using this solution.

Optimizing loading path and die linetype of large length-to-diameter ratio metal stator screw lining hydroforming

In order to meet the high temperature environment requirement of deep and superdeep well exploitation, a technology of large length-to-diameter ratio metal stator screw lining meshing with rotor is presented. Based on the elastic-plasticity theory, and under the consideration of the effect of tube size, material mechanical parameters, friction coefficient and loading paths, the external pressure plastic forming mechanical model of metal stator screw lining is established, to study the optimal loading path of metal stator lining tube hydroforming process. The results show that wall thickness reduction of the external pressure tube hydroforming(THF) is about 4%, and three evaluation criteria of metal stator screw lining forming quality are presented: fillet stick mold coefficient, thickness relative error and forming quality coefficient. The smaller the three criteria are, the better the forming quality is.Each indicator has a trend of increase with the loading rate reducing, and the adjustment laws of die arc transition zone equidistance profile curve are acquired for improving tube forming quality. Hence, the research results prove the feasibility of external pressure THF used for processing high-accuracy large length-to-diameter ratio metal stator screw lining, and provide theoretical basis for designing new kind of stator structure which has better performance and longer service life.

基于模糊快速滑模的农用牵引车辆直线路径跟踪控制

为解决无人驾驶牵引式农机在非结构化环境中作业时直线跟踪精度低、上线速度慢、抗干扰能力差等问题,提出了一种基于模糊快速滑模控制的农用牵引式车辆直线路径跟踪控制方法。首先利用车辆运动学模型与参考路径建立牵引车辆直线路径跟踪误差模型,并提出一种基于模糊参数整定的快速滑模直线路径跟踪方法,解决了滑模控制算法的控制器抖振与机具快速上线问题。通过Lyapunov稳定性分析可知,所设计控制方法可保证牵引机具跟踪参考路径,同时铰接角收敛至零。最后,基于Simulink仿真与实车试验对该控制方法的有效性与优越性进行测试。田间实车试验表明,使用本文控制方法时,拖车和挂车最大路径跟踪横向误差分别为0.11、0.12 m,拖车和挂车跟踪误差方差分别为0.0013、0.0015 m^(2);相较于传统基于等速趋近律设计的滑模控制器,上线时间提升约58%,最大跟踪误差减小约66%。

高校生理学课程思政建设路径的探索与实践

以生理学课程为例,在教学中充分挖掘生理学知识中蕴含的思政元素,把案例故事与专业知识有机结合,以案例故事作为支撑“点”,其中贯穿爱国情怀与责任、科学精神、敬畏生命、医学人文素养、中医药文化自信等育人主“线”,再映射到“理、法、情”3个层“面”中的对应思政元素。采用以点带线、以线扩面、多维结合的模式构筑“教师—课程—学生”一体化生理学课程思政建设路径,增强课程育人效果。

基于空程和方向的船体装配线划线路径优化

为解决复杂船体装配线划线路径优化时精度低和收敛速度慢的问题,进而提高数控划线枪的作业效率,提出了基于空程和方向的船体装配线划线路径的调参免疫优化。首先以装配线的划线顺序和划线方向建立目标函数;然后借鉴凸透镜虚实成像原理设计了新免疫优化算法,基于进化代数和种群浓度自适应调节交叉和变异概率,并引入疫苗操作实现了船体装配线划线路径求解;最后基于马尔科夫链理论证明了免疫优化算法的收敛性。六组高维函数测试结果表明,与遗传算法、免疫遗传算法和自适应改进遗传算法相比,所提算法实现了100%寻优,且最小收敛代数、平均收敛代数、迭代代数标准差分别平均减少了29.63%、28.96%和18.33%。四种船体结构的装配线划线路径优化测试结果表明,相比起其他三种算法,所提算法的路径规划性能最佳,其最小值和平均值分别平均减少了1.38%和2.39%,平均收敛代数和迭代代数标准差分别平均减少了17.19%和13.08%,从而进一步验证了船体装配线划线路径调参免疫优化的有效性和优越性。

面向海底管道巡检的AUV三维自适应路径跟踪

针对面向海底管道巡检任务的欠驱动自主水下航行器(AUV)三维路径跟踪控制问题进行研究。首先,在固定坐标系和机体坐标系下建立AUV的运动学模型,为设计适宜运动控制的三维路径跟踪控制器,建立流体坐标系,并在Serret-Frenet坐标系下建立AUV的路径跟踪误差模型;其次,将可变前视距离引入传统视线(LOS)制导策略,提出一种自适应LOS制导策略以提高制导精度,并基于此设计面向海底管道巡检的AUV三维路径跟踪控制器,使得AUV可有效跟踪设定的参数化路径;最后,基于李雅普诺夫稳定性理论证明了闭环系统的稳定性。仿真结果验证了所提面向海底管道巡检的三维路径跟踪控制器的有效性。研究成果能够改善AUV的操纵性,可为面向海底管道巡检的无人水下航行器路径跟踪控制方法提供参考。

Role of the STAT3/survivin signaling pathway in the EML4-ALK-positive lung adenocarcinoma cell line H2228 before and after crizotinib-induced resistance

Objective This study investigated the role of the STAT3/survivin signaling pathway in the EML4-ALK–positive lung adenocarcinoma cell line H2228 before and after crizotinib-induced resistance. The mechanism of resistance was studied. Methods Cell viability was determined using the MTT assay. Crizotinib-induced apoptosis in H2228 and H2228 crizotinib-resistant cells treated with the indicated doses of crizotinib was measured at different times(24 h, 48 h, 72 h) using flow cytometry. The levels of p-ALK, ALK, p-STAT3, STAT3, and survivin after treatment of cells with 0, 0.3, and 1 μM crizotinib for 72 h were determined using Western blot analysis. DNA sequencing was used to identify mutations in H2228 crizotinib-resistant cells. Results The crizotinib IC50 values in H2228 and H2228 crizotinib-resistant cells at 72 h were 334.5 n M and 3418 n M, respectively. The resistance index of H2228 crizotinib-resistant cells was 10.20. Crizotinib induced apoptosis in H2228 cells and reduced the levels of p-ALK, p-STAT3, and survivin. In contrast, no changes in the levels of p-ALK, p-STAT3, and survivin were observed in H2228 crizotinib-resistant cells. The mutations 2067G→A and 2182G→C in EML4-ALK were present in the H2228 crizotinib-resistant cells. Conclusion Crizotinib decreased the viability of H2228 cells in a dose- and time-dependent manner. In the STAT3/survivin pathway, downregulation of p-ALK, p-STAT3, and survivin might contribute to crizotinib-induced apoptosis in H2228 cells. However, the STAT3/survivin pathway in H2228 crizotinib-resistant cells was unaffected by crizotinib treatment. Acquired resistance in H2228 cells might be related to ALK mutations.

基于人工磁场的防疫机器人路径规划

针对传统人工势场法在防疫机器人路径规划过程中容易陷入局部极小值和目标不可达的问题,提出一种基于人工磁场的路径规划算法。首先,对障碍物周围建立人工磁场,引入洛伦兹力,洛伦兹力与引力保持垂直,避免机器人陷入局部极小值点;其次,在洛伦兹力函数中引入机器人与目标点的距离影响因子,解决目标不可达问题;再次,通过建立目标点与障碍物之间的虚拟直线优化洛伦兹力的方向,避免迂回路径,减少路径规划的步数。最后,在MATLAB环境下对传统人工势场法和人工磁场法进行了仿真实验,实验结果表明,人工磁场法可以克服局部极小值和目标不可达问题,规划的路径对障碍物进行了避障,避免了徘徊振荡的情况出现,提高了路径规划的质量。

IGCT门阴极换流路径杂散阻抗在线监测方法研究

集成门极换流晶闸管(integrated gate commutated thyristor,IGCT)换流路径杂散阻抗是评估其关断能力的重要参数,现有离线测量方法有诸多缺陷并且测试过程复杂,实时性差。该文主要针对IGCT换流路径杂散阻抗在线监测问题,结合IGCT关断过程,分析了换流路径杂散阻抗的构成;根据基尔霍夫电流定律(Kirchhoff’s current law,KCL)、基尔霍夫电压定律(Kirchhoff’s voltage law,KVL)推导了换流路径电压、电流方程,进而提出基于阴极集成印刷电路板(printed circuit board,PCB)式电流传感器的换流路径杂散参数在线监测方法;采用高速采集卡和LabVIEW软件,构建了测量系统;通过在高压、大电流加速老化测试平台上的实际测试,实现了mΩ级电阻与nH级电感的杂散阻抗准确提取,验证了在线监测方法的有效性。

基于主应力轨迹线的连续碳纤维复合材料3D打印路径规划方法

连续碳纤维复合材料3D打印成型零件的力学性能对纤维的铺设方向有需求,传统的路径规划方法基于零件的形状轮廓进行填充,不能满足零件的实际使用性能。针对这一问题,提出基于主应力轨迹线的连续碳纤维复合材料3D打印路径规划方法。基于连续碳纤维复合材料三维模型的有限元分析数据,通过材料力学计算得到相应的主应力轨迹线;通过连续碳纤维复合材料3D打印的打印参数对得到的主应力轨迹线进行调控,保证每一条轨迹线之间的间距契合3D打印要求;通过坐标变换调整有限元分析坐标系以及打印机坐标系;通过以上调控生成用于连续碳纤维复合材料3D打印的G code规划文件。通过路径规划仿真对比和打印拉伸实验,基于主应力轨迹线生成的连续碳纤维复合材料3D打印路径比传统直线碳纤维复合材料3D打印路径性能提高了4.5%,验证了基于主应力轨迹线的连续碳纤维复合材料3D打印路径规划方法的有效性。

促进时空可达的高校新校区步行路网优化——以重庆医科大学缙云校区为例

可达性是高校校园步行出行的基本要求.然而,我国高校新校区既有步行路网存在局部空间可达水平偏低、近距离绕行等问题.本研究以重庆医科大学缙云校区为例,采用空间句法理论下的线段模型和ArcGIS最优路径分析模型,量化其步行时空可达水平;结合步行空间实际使用水平,提出校园步行路网的改善方案并评估方案的步行可达性.研究发现:(1)分级的步行路网可提升全局和局部空间可达性,精细的道路设施设计可确保实际使用的可达性;(2)有序的游憩步道可增强空间感知的可达性;(3)以吸引点为导向的步行捷径可改善时间可达性.

基于决策树的电网重要用户供电路径决策方法

广州等超大城市电网中110kV网架接线主要为3T接线,其运行方式多变,对电网的规划和运行有很大影响。超大城市电网中存在着大量的重要用户,其供电可靠性是安排电网运行方式的一个重要考虑因素。若安排的运行方式使得某些重要用户的供电路径汇集在同一元件,就会大大降低重要用户的供电可靠性。基于此,建立超大城市电网重要用户供电路径优化决策模型,以最小化电网中220kV线路的平均负载率为目标,要求系统的每个重要用户都要满足多个供电路径来自最少2个不同的220kV变电站。为了快速求解此混合整数非线性规划模型,引入多变量决策树将模型转化成一个整数非线性规划问题,再通过变量代换将其转化为一个整数线性规划问题,实现快速准确求解。最后,以广州电网实际数据为例,验证所提优化决策模型和求解方法的可行性与有效性。

基于AGV的螺栓自动收集转运流水线的设计与应用

自动导引车(Automatic Guided Vehicle,AGV)是智能制造车间的重要载体,其转运路径对车间生产效率有很大影响。本文针对螺栓转运生产线进行数学建模,对螺栓产量、转运路径距离以矩阵形式建立计算表,通过算例分析完成螺栓转运物流量的数值计算,并以此提供路径优化方向。基于设备及生产车间实际情况,完成螺栓自动收集转运流水线的设计,并进行实践验证。结果表明:AGV转运路径优化后,以AGV收集转运为主,传送带传送、自动倒运装置等设备为辅的自动收集转运流水线基本可以实现螺栓在各工序生产设备间的智能化、自动化收集转运,提高了产品生产率。

基于传递路径影响消除的滚动轴承故障特征增强

受到复杂传递路径的影响,滚动轴承故障产生的周期性冲击成分常被强背景噪声所淹没,进而给故障特征的有效提取带来极大难度。对此,研究了一种基于传递路径影响消除的滚动轴承故障特征增强方法。首先,分析了激励信号、传递函数和响应信号之间的关系,提出一种基于趋势线的传递路径影响消除方法,提高了故障特征成分占比;其次,利用频谱编辑方法,在保证趋势线提取准确性的同时,抑制信号中谐波成分的干扰,进一步突出了信号中的故障特征;最终借助包络分析处理特征增强后的信号,在频域范围内实现滚动轴承故障特征的准确提取。借助仿真和实测信号对方法的有效性进行验证,结果表明,该方法能够消除复杂传递路径的影响,有效增强滚动轴承故障特征,验证了方法的可行性。

基于AI专线传输电路约束路径计算的应用

近年来运营商专线业务竞争进入白热化阶段,对专线开通的时效性、准确性要求越来越高,传统的人工方式无法应对专线业务传输电路相关数据制作竞争的要求。文中通过对传输电路约束路径计算方法进行研究,并将算法工具化。基于AI分析的专线传输电路约束路径计算工具能够对接传输工作台相关数据作为数据库,通过研发数据库上的关联规则算法对专线传输电路业务路径进行规划,实现电路调度自动开通,提供完整电路的开通、调整、停闭流程,保障业务的快速开通、提高专线开通的时效性和准确性。

自由曲面粗加工分层行切刀轨规划方法

粗加工分层行切刀轨加工效率高、适用范围广,但在加工自由曲面时相邻行刀轨连接处容易产生过切或切削余量过大。针对三轴数控粗加工的不足,提出了一种分层行切刀轨规划方法:获取加工平面上的曲面轮廓,以初始刀轨与轮廓交点定义加工区域,并以交点邻域的局部轮廓计算出无干涉刀位点;向相邻行刀轨搜索不与轮廓线发生干涉的刀位点进行连接,对连接刀轨提出以精度为约束的离散特征点计算逼近误差的方法,通过新增过渡刀位点使最终的连接刀轨逼近误差低于最大允许值。所提出的方法对包含自由曲面的零件生成了刀轨,并进行仿真加工,结果验证了方法的可行性。

资产负债表冲击:表现与修复路径

2023年以来,受地产行业低迷、信心不足与预期偏弱等因素影响,中国实体经济部门资产负债表受到一定冲击,且居民和企业部门更为明显,但现在断言中国陷入资产负债表衰退为时尚早。通过分析中国三部门资产负债表表现,发现影响中国资产负债表修复的三条逻辑主线:多重因素影响下居民行为函数发生变化带来超额储蓄、提前还贷、消费降级等现象;企业经营目标从利润最大化转向“求生存”,导致投融资下滑显著;债务约束下政府部门还本付息压力加大,扩表能力和意愿有限。而房地产的深度调整是这三者资产负债表变化的逻辑交点。最后,本文从短期调控和长期改革两方面提出修复路径与政策建议。