The manufacture and maintenance of large parts in ships,trains,aircrafts,and so on create an increasing demand for mobile machine tools to perform in-situ operations.However,few mobile robots can accommodate the compl...The manufacture and maintenance of large parts in ships,trains,aircrafts,and so on create an increasing demand for mobile machine tools to perform in-situ operations.However,few mobile robots can accommodate the complex environment of industrial plants while performing machining tasks.This study proposes a novel six-legged walking machine tool consisting of a legged mobile robot and a portable parallel kinematic machine tool.The kinematic model of the entire system is presented,and the workspace of different components,including a leg,the body,and the head,is analyzed.A hierarchical motion planning scheme is proposed to take advantage of the large workspace of the legged mobile platform and the high precision of the parallel machine tool.The repeatability of the head motion,body motion,and walking distance is evaluated through experiments,which is 0.11,1.0,and 3.4 mm,respectively.Finally,an application scenario is shown in which the walking machine tool steps successfully over a 250 mmhigh obstacle and drills a hole in an aluminum plate.The experiments prove the rationality of the hierarchical motion planning scheme and demonstrate the extensive potential of the walking machine tool for in-situ operations on large parts.展开更多
针对五桥臂逆变器输出存在的反向电压脉冲问题,本文提出了一种基于有限状态机(finite state machine,FSM)的五桥臂逆变器改进调制策略。首先,深入分析了反向电压脉冲的产生机理以及给电机调速系统运行带来的危害。在上述分析的基础上,...针对五桥臂逆变器输出存在的反向电压脉冲问题,本文提出了一种基于有限状态机(finite state machine,FSM)的五桥臂逆变器改进调制策略。首先,深入分析了反向电压脉冲的产生机理以及给电机调速系统运行带来的危害。在上述分析的基础上,依据电压源逆变器空间矢量脉宽调制理论,通过对电压空间矢量脉宽分布进行优化调整,实现了改进的五桥臂逆变器调制策略,从机理上抑制了反向电压脉冲的产生。本文将提出的改进调制策略与原有的空间矢量脉宽调制策略进行了实验比较,实验结果表明该调制策略不仅实现了对两台电机的独立控制,而且有效的改善了五桥臂逆变器的输出电压质量,特别是使开关频率附近的电压高次谐波分量减小到原有的1/4。展开更多
基金Funded by the National Natural Science Foundation of China(Grant No.U1613208)the National Key Research and Development Plan of China(Grant No.2017YFE0112200)the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement No.734575.
文摘The manufacture and maintenance of large parts in ships,trains,aircrafts,and so on create an increasing demand for mobile machine tools to perform in-situ operations.However,few mobile robots can accommodate the complex environment of industrial plants while performing machining tasks.This study proposes a novel six-legged walking machine tool consisting of a legged mobile robot and a portable parallel kinematic machine tool.The kinematic model of the entire system is presented,and the workspace of different components,including a leg,the body,and the head,is analyzed.A hierarchical motion planning scheme is proposed to take advantage of the large workspace of the legged mobile platform and the high precision of the parallel machine tool.The repeatability of the head motion,body motion,and walking distance is evaluated through experiments,which is 0.11,1.0,and 3.4 mm,respectively.Finally,an application scenario is shown in which the walking machine tool steps successfully over a 250 mmhigh obstacle and drills a hole in an aluminum plate.The experiments prove the rationality of the hierarchical motion planning scheme and demonstrate the extensive potential of the walking machine tool for in-situ operations on large parts.
文摘针对五桥臂逆变器输出存在的反向电压脉冲问题,本文提出了一种基于有限状态机(finite state machine,FSM)的五桥臂逆变器改进调制策略。首先,深入分析了反向电压脉冲的产生机理以及给电机调速系统运行带来的危害。在上述分析的基础上,依据电压源逆变器空间矢量脉宽调制理论,通过对电压空间矢量脉宽分布进行优化调整,实现了改进的五桥臂逆变器调制策略,从机理上抑制了反向电压脉冲的产生。本文将提出的改进调制策略与原有的空间矢量脉宽调制策略进行了实验比较,实验结果表明该调制策略不仅实现了对两台电机的独立控制,而且有效的改善了五桥臂逆变器的输出电压质量,特别是使开关频率附近的电压高次谐波分量减小到原有的1/4。
