Luffing mechanism is a key component of the construction machinery.This paper proposes a two degree of freedom(2-DOF)luffing mechanism,which has one more pair of driving cylinders than the single DOF luffing mechanism...Luffing mechanism is a key component of the construction machinery.This paper proposes a two degree of freedom(2-DOF)luffing mechanism,which has one more pair of driving cylinders than the single DOF luffing mechanism,to improve the performance of the machinery.To establish the dynamic model of the 2-DOF luffing mechanism,firstly,we develop a hierarchical method to deduce the Jacobian matrix and Hessian matrix for obtaining the kinematics equations.Subsequently,we divide the luffing mechanism into six bodies considering actuators,and deduce the kinetic equations of each body by the Newton-Euler method.Based on the dynamic model,we simulate the luffing process.Finally,a prototype is built on a pile driver to validate the model.Simulations and experiments show that the dynamic model can reflect the dynamic properties of the proposed luffing mechanism.And the control strategy that the front cylinders retract first shows better mechanical behavior than the other two control strategies.This research provides a reference for the design and application of 2-DOF luffing mechanism on construction machinery.The modeling approach can also be applied to similar mechanism with serial closed kinematic chains,which allows to calculate the dynamic parameters easily and exactly.展开更多
针对气象雷达系统任务过程安全性问题,以基于系统论的事故模型及过程(systems-theoretic accident model and process)理论方法为基础,提出了一种案例激励安全性分析方法。在进近阶段机载气象雷达任务过程中,通过构建系统分层控制结构,...针对气象雷达系统任务过程安全性问题,以基于系统论的事故模型及过程(systems-theoretic accident model and process)理论方法为基础,提出了一种案例激励安全性分析方法。在进近阶段机载气象雷达任务过程中,通过构建系统分层控制结构,识别系统任务过程中存在的不安全控制行为,并辨识与不安全控制行为关联的潜在危险致因;构建安全飞行控制结构模型,以达美航空事故为例,提出安全约束建议控制事故衍变机制来优化模型,以提高系统任务过程安全。以上分析表明,该方法能更全面地识别系统深层危险致因,为机载气象雷达的安全性设计提供技术支持。展开更多
基金Project(2015B020238014)supported by the Science and Technology Program of Guangdong Province,China。
文摘Luffing mechanism is a key component of the construction machinery.This paper proposes a two degree of freedom(2-DOF)luffing mechanism,which has one more pair of driving cylinders than the single DOF luffing mechanism,to improve the performance of the machinery.To establish the dynamic model of the 2-DOF luffing mechanism,firstly,we develop a hierarchical method to deduce the Jacobian matrix and Hessian matrix for obtaining the kinematics equations.Subsequently,we divide the luffing mechanism into six bodies considering actuators,and deduce the kinetic equations of each body by the Newton-Euler method.Based on the dynamic model,we simulate the luffing process.Finally,a prototype is built on a pile driver to validate the model.Simulations and experiments show that the dynamic model can reflect the dynamic properties of the proposed luffing mechanism.And the control strategy that the front cylinders retract first shows better mechanical behavior than the other two control strategies.This research provides a reference for the design and application of 2-DOF luffing mechanism on construction machinery.The modeling approach can also be applied to similar mechanism with serial closed kinematic chains,which allows to calculate the dynamic parameters easily and exactly.
文摘针对气象雷达系统任务过程安全性问题,以基于系统论的事故模型及过程(systems-theoretic accident model and process)理论方法为基础,提出了一种案例激励安全性分析方法。在进近阶段机载气象雷达任务过程中,通过构建系统分层控制结构,识别系统任务过程中存在的不安全控制行为,并辨识与不安全控制行为关联的潜在危险致因;构建安全飞行控制结构模型,以达美航空事故为例,提出安全约束建议控制事故衍变机制来优化模型,以提高系统任务过程安全。以上分析表明,该方法能更全面地识别系统深层危险致因,为机载气象雷达的安全性设计提供技术支持。
