【作者】 娄军强；

【导师】 魏燕定；

【作者基本信息】 浙江大学 ， 机械制造及其自动化， 2013， 博士

【摘要】 空间柔性机械系统的轨迹跟踪和振动抑制问题是当前柔性结构和航天科技领域中及其重要又富有挑战性的课题。本学位论文在国家自然科学基金的资助下,以空间柔性机械臂系统的运动控制和振动抑制技术为研究背景,以一类由压电致动器/传感器、伺服电机减速器驱动结构和柔性臂等构成的典型智能空间柔性机械臂系统为研究对象,研究了伺服电机和压电致动器联合作用下柔性臂系统的动力学特性,并建立系统的动力学模型和驱动模型；解决了系统中致动器/传感器的优化配置问题；深入研究了空间柔性机械臂系统的抑振轨迹规划机理和优化算法；确定了柔性臂系统的运动控制策略和振动抑制策略,最终实现了在伺服电机驱动和压电致动器主动控制下空间柔性机械臂系统的轨迹跟踪和振动抑制一体化控制。提高了系统的运动控制精度和工作效率。以一类包含伺服电机、减速器、柔性臂、末端操作对象以及压电致动器/传感器在内的空间柔性机械臂系统为研究对象,基于假设模态法和Hamilton原理建立了系统的动力学方程。并对伺服电机的驱动机理进行研究,提出了考虑摩擦力矩、减速器及柔性臂弹性振动的耦合反力矩的伺服电机机电耦合模型。基于线性二次最优控制理论,提出了致动器/传感器的复合优化配置准则,该准则包含两个控制指标：①综合柔性臂弹性振动能量、压电致动器控制能量,系统刚体转动能量、以及伺服电机驱动能量的LQR综合能量指标；②致动器引入对系统特性影响的系统结构固有频率变化率指标。然后采用改进的多岛遗传算法得到了不同频率变化率指标下,一组、两组压电致动器/传感器的尺寸、位置和控制增益的最优配置结果。从系统动力学方程出发,揭示了伺服电机驱动、压电致动器主动控制下空间柔性机械臂系统的抑振轨迹规划机理,提出了包含系统柔性部分激振力矩和刚性部分驱动力矩的综合指标。并选择激起柔性臂振动较小的五次多项式样条函数作为轨迹优化的基础曲线和插值曲线,利用改进的多岛遗传算法对空间柔性机械臂系统的运动轨迹进行优化,得到了综合指标最小的最优抑振轨迹。引入奇异摄动因子对系统动力学方程进行分解,分别推导得到系统基于奇异摄动模型的快、慢子系统动力学方程。针对快、慢子系统在各自时标下的动力学特性,对具有强耦合性及强非线性的慢变子系统提出模糊滑模控制策略；而对由于模态截断带来模型不确定性以及多模态特性的快变子系统采用分级自适应模糊PID控制策略,从而实现了空间柔性机械臂系统在伺服驱动电机和压电致动器联合控制下的轨迹跟踪和振动抑制一体化控制,提高了系统的运动精度和操作效率。更多还原

【Abstract】 Trajcectory tracking of space flexible manipulators together with suppressing their vibrations during their operation has been the main concern of many recent stuies in aeronautics and robotics. This thesis is mainly concerned with trajcectory tracking and vibration suppression control of a typical space flexible manipulator system using piezoelectric actuators. Funded by National Natural Science Foundation, dynamic modeling of the flexible manipulator system, optimal placing of the actuators/sensors, optimal trajectory planning for vibration suppression of the manipulator and the integrated control strategies for trajcectory tracking and vibration suppression of the system are studied deeply in this dissertation. The main contents of this dissertation are as follows:In chapter1. scientific backgrounds and siganificances of this thesis are presented. Then, state-of-art for several key technologies concerning this field are elaborated. The structure and main contents of this dissertation are depicted.In chapter2. a dynamic model of the space flexible manipulator system is drived using extended Hamilton’s principle with discretization by the assumed mode method. In addition, introduced the friction torque and the coupling torque between the motor and the flexible manipulator, dynamics of the driving set-up(sevo-motor and harmonic gear)is described. In the end. a further verification of the dynamic characterics of the system is made through numerical simulation.The objective of chapter3is to determine the optimal locations of multiple distributed actuators/sensors. The dynamic model in chapter2is converted to state space form for control design. To find the optimal location of piezoelectric sensor/actuator pairs, a hybrid optimization strategy combined with minimization of the input energy, maximization of the transferring energy and minimization of natural frequencies changes is proposed. The performance criterion is composed of two parts:(1)a LQR performance criterion including flexible vibration energy, rigid motion energy and driving energy of the motor.(2) The change ratio of the natural frequencies. To solve this complex multi-objective optimization problem, a modified Multi-Island Genetic Algorithm (MIGA) is developed for identifying optimal sizing and location of piezoelectric patches as well as the optimal feedback control gains. Also, a series of comparable research is implemented in different conditions.In chapter4. an optimal trajectory planning technique for suppressing vibrations of the system is proposed. At first, vibrations responses of the manipulator between polynomial and cycloidal motions are compared. Then, the principle of optimal trajectory planning technique for suppressing vibrations of the flexible manipulator system, which is controlled by the sevo-motor and piezoelectric actuators, are elucidated, and a performance criterion considering the exciting torque for the flexible part and the driving torque for the rigid part is presented. In order to get the displacement, the five order polynomial functions, which arouses less vibrations, is used to constructe and interpolate the discrete displacements. And the optimal trajectory is found using Multi-Island Genetic Algorithm (MIGA), again. It is confirmed from the simulation results that the proposed trajectory planning technique is effective in suppressing vibrations of the flexible manipulator.In Chapter5, it deals with the integrated control strategies of trajectory tracking and vibration suppression for the space flexible manipulator system with PZT actuators. Using the singular perturbation theory, the flexible-rigid-coupled dymanics of the system, is separated into flexible and rigid subsystems, by considering the fact that it takes place in two time scales. And then, a composite control strategy consisting of a fuzzy sliding controller for slow subsystem and a hierarchical fuzzy PID controller for fast subsystem is developed. According to the numerical simulation results, it can be concluded that the proposed integrated control strategies have a suitable and efficient performance for trajectory tracking and suppressing vibrations of the flexible manipulator in different intial contiditons and trajectories. Both motion precision and operation efficiency are improved.In chapter six. experimental system of the space flexible manipulator is set up, and the corresponding software and hardware are summarized. Experimental studies on system dynamics, optimal locations of multiple distributed piezoelectric actuators/sensors, optimal trajectory planning for suppressing vibrations and the integrated control strategies of trajectory tracking and vibration suppression are elaborated respectively.Conclusions and prospects are briefly depicted at the end of this thesis.更多还原