【作者】 皮阳军；

【导师】 王宣银；

【作者基本信息】 浙江大学 ， 机械电子工程， 2010， 博士

【摘要】 舰船运动模拟器以其优越的可控性、无破坏性、经济性、可靠性等优点,得到了广泛的应用。电液伺服并联六自由度机构作为舰船运动模拟器的驱动机构,具有位置精度高、承载能力强等优点。轨迹跟踪性能是并联六自由度机构的重要性能指标之一,随着应用的需要,人们对轨迹跟踪性能的要求越来越高。然而,并联六自由度机构本身是一个多输入多输出强耦合非线性系统,且与电液伺服系统的非线性因素互相耦合,这对电液伺服并联六自由度机构的高精度控制提出了挑战。另一方面,在舰船运动模拟器运行时,常常会受到来自外界的不确定干扰,这也给系统的控制带来了难度。本论文以电液伺服并联六自由度机构作为研究对象,采取理论分析、建模仿真与实验相结合的方法,系统地研究了不确定干扰下电液伺服并联六自由度机构的轨迹跟踪控制方法,并将其应用到舰船装备动态环境模拟研究中。主要研究内容如下：第一章,介绍了课题来源及背景,在查阅国内外文献的基础上,介绍了舰船运动模拟器的研究情况。对并联六自由度机构的研究情况特别是并联六自由度机构控制技术的研究现状和发展趋势进行了综述,并提出了目前并联六自由度机构控制需要解决的几个问题。根据课题的研究目标,提出了本课题的主要研究内容。第二章,对并联六自由度机构进行了数学建模,给出了并联六自由度机构的运动学和动力学模型。在此基础上,提出一种基于关节力传感器的并联六自由度机构结构参数标定方法。仿真和实验均证明,该方法对并联六自由度机构的精度有明显的改进,为实现系统的高精度控制提供了条件。第三章,对并联六自由度机构存在的不确定干扰进行分析,提出一种利用关节力传感器获取不确定干扰信息的方法,从而将并联六自由度机构分解成各自独立的关节进行控制。给出了关节电液伺服系统的数学模型,并推导了关节鲁棒自适应控制器。仿真和实验证明该方法对不确定外干扰具有明显的抑制作用。第四章,提出了基于关节空间干扰观测器的并联六自由度机构级联控制方法,将非线性干扰观测器、滑模控制器和级联控制方法相结合用于电液伺服并联六自由度机构的控制。通过利用关节干扰观测器代替关节力传感器以获取不确定干扰信息,减少了成本。采用级联控制方法将液压驱动器非线性动态引入控制器设计。控制器为内环和外环级联结构,内环采用反馈线性化理论进行设计,外环采用滑模控制方法。仿真和实验表明,在不额外增加传感器的情况下,该方法能有效克服外干扰的影响。第五章,对基于关节空间干扰观测器的并联六自由度机构协同控制方法进行了研究。定义了并联六自由度机构同步误差,并设计协同控制器使得关节误差与同步误差均渐进收敛,从而使得整个系统各关节协同运动。该方法解决了并联六自由度机构基于关节空间控制方法各关节控制器无法协同工作的问题。仿真和实验表明,该方法在保证各关节控制性能的同时,能有效提高系统协同性。第六章,对并联六自由度机构基于工作空间的控制方法进行了研究。利用并联六自由度机构的运动学正解作为工作空间的反馈信号设计控制器。考虑到一般滑模控制和自适应控制的不足,定义综合干扰概念,并通过设计自适应干扰观测器消除综合干扰。利用反步法(Backstepping)推导出控制器。仿真和实验表明,综合干扰观测器能有效补偿系统不确定干扰,控制性能较好。第七章,提出一种频域／时域双环的并联六自由度机构多自由度功率谱复现的方法。此方法分为时域内环和频域外环,其中时域内环采用本论文前述的电液位置伺服控制方法,频域外环将目标功率谱信号转换为时域驱动信号。该方法不需要安装加速度传感器,仅利用舰船运动模拟器本身的关节位移传感器即可进行六自由度的功率谱复现。第八章,总结了本课题的研究成果、结论和创新点,并对后续研究工作做出了展望。更多还原

【Abstract】 Ship motion simulators have been used in various applications, due to their advantages such as superior controllability, non-destructivity, economical efficiency, high reliability, etc. Ship motion simulators are often driven by electro-hydraulic six degree of freedom (6DOF) parallel mechanisms, due to the high precision, high capacity and so on. High trajectory tracking accuracy is an important criterion for the use of 6DOF parallel mechanisms. However, the control of electro-hydraulic 6DOF parallel mechanism is challenging as its dynamics is highly nonlinear. Furthermore, the control of hydraulic actuators is more challenging than that of their electrical counterparts, due to the phenomena such as nonlinear servo valve flow-pressure characteristics, fluid compressibility, and valve overlap. On the other hand, the ship motion simulators often subject to uncertainty disturbances from the external environment. This thesis addresses the study of electro-hydraulic 6DOF parallel mechanism. With the help of theoretical analysis, simulation and experimental research, the trajectory tracking control of the 6DOF parallel mechanism with uncertain disturbance is investigated systemically. Then, the application to the simulation of ship equipment in a dynamic environment is studied.This doctoral dissertation consists of eight chapters. The main contents are as follows:In Chapter 1, the support and background of the research is introduced. On the basis of referring to domestic and international associated documents, the overview of ship motion simulators is summarized. Then, the present research situation and trends of 6DOF parallel mechanism and control of 6DOF parallel mechanism are reviewed, and several issues to be resolved are proposed. Finally, the research object and main research content of the subject are illustrated.In Chapter 2, the mathematic model of 6DOF parallel mechanism is derived. Then, based on joint force sensors, a structure parameter calibration method of 6DOF parallel mechanism is proposed. Simulation and experimental results show that this method significantly improves the accuracy of 6DOF parallel mechanism. This chapter provides a basis for high precise control of 6DOF parallel mechanism.In Chapter 3, according to analysis the uncertain disturbances of 6DOF parallel mechanism, the method which uses force sensors to measure load forces is proposed. Through using force sensors, the 6DOF parallel mechanism has been decoupled into six independent legs. Then, the mathematical model of hydraulic system is given, and the adaptive robust controller is derived. Simulation and experimental results show that the proposed controller gives a good performance for the specified tracking task in the presence of uncertain load disturbances.In Chapter 4, observer-based cascade control of 6DOF parallel hydraulic mechanism in joint space coordinate is proposed. Cascade control, nonlinear disturbance observer technique and sliding mode control are integrated to design the controller for 6DOF parallel hydraulic mechanism. In order to reduce costs, disturbance observer, instead of force sensor, is used to obtain disturbance information. Hydraulic actuator dynamics models are incorporated in the controller design by using cascade control algorithm. This algorithm is applied to separate the hydraulic dynamics from the mechanical part, which can mask the hydraulic dynamics with an inner loop. The inner loop controller is designed based on the feedback linearization, and the outer loop is derived by using sliding mode control. Simulation and experimental results confirm the effectiveness of the method.In Chapter 5, observer-based synchronous tracking control of 6DOF parallel mechanism in joint coordinate is studied. The position synchronization error is developed by considering motion synchronization between each actuator joint and its adjacent one based on the synchronous goal. Then the controller is designed with feedback of both position error and synchronization error. The proposed controller is proven to guarantee asymptotic to convergence to zero of both the position errors and synchronization errors. This method solves the problem that joint space control scheme cannot guarantee 6DOF parallel mechanism to work in a synchronous manner. Simulation and experimental results confirm that this method guarantees the tacking accuracy in joint space and can effectively improve system interoperability at the same time. In Chapter 6, the task space control of 6DOF parallel mechanism is developed. The direct kinematics of 6DOF parallel mechanism is used as feedback signal to design controller. Considering the drawbacks of conventional sliding mode control and adaptive control, a lumped disturbance which synthesizes both parametric uncertainties, uncertain external disturbance and un-modeled dynamics is first defined. An adaptive disturbance observer is then constructed to estimate and compensate the lumped disturbance. The backstepping design method is adopted to derive the controller. Simulation and experimental results confirm the effectiveness of the method.In Chapter 7, the method which uses ship motion simulator to reproduce the power spectrum with frequency domain loop and time domain loop is proposed. This method is divided into time domain inner loop and frequency domain outer loop. The aforementioned electro-hydraulic servo control method can be used in the time domain loop. The target power spectrum signal is converted into time domain drive signal in the frequency domain loop. This method does not require additional acceleration sensors, and can be used in ordinary shaking table.In Chapter 8, the main research work, conclusions and innovation points of this thesis are summarized. Then, future development is predicted in order to provide references for the further research on this project.更多还原