【作者】 朱大昌；

【导师】 方跃法；

【作者基本信息】 北京交通大学 ， 机械设计及理论， 2008， 博士

【摘要】 本文提出采用四自由度并联机构(4-SPS(PS))及六自由度并联机构(Stewart平台)作为动、静基座车载雷达天线自动调平系统的支撑机构,并对动、静基座自动调平平台并联支撑机构运动学、动力学进行分析。在此基础上,对静基座大负荷及动基座机动实时调平两种不同应用场合,分别采用带观测器的滑模变结构控制及基于随机预测模型的变结构广义预测控制进行了自动调平平台控制系统设计及自动调平特性闭环控制仿真对比研究。具体内容如下:◆基于分析传统调平平台调平特性前提下,提出采用四自由度并联机构(4-SPS(PS)型)及六自由度并联机构(Stewart平台)作为动、静基座车载雷达天线自动调平系统的支撑结构,并对机构的位姿、运动学、动力学特性等方面进行分析与研究,基于SimMechanics建立并联支撑机构实验仿真模型。采用线性状态反馈解耦方法实现静基座车载雷达天线自动调平平台Stewart型并联支撑机构多通道液压伺服系统解耦。分别对动、静基座并联支撑机构各支链驱动器受力、驱动器速度进行分析,为驱动器选型提供依据。分析了动、静基座车载雷达天线自动调平平台在开环控制条件下的调平性能。◆根据车载雷达天线自动调平系统高精度、高频带及快速响应等性能指标,本文采用电液位置伺服系统作为动/静基座车载雷达天线自动调平平台并联支撑结构的驱动装置。在深入分析电液位置伺服系统机理的基础上,建立了阀控非对称缸液压位置伺服系统的数学模型。对静基座车载雷达天线自动调平平台液压伺服系统的开环频率响应特性进行分析;对动基座车载雷达天线自动调平平台液压伺服系统的瞬态响应能力、频率响应带宽进行分析,并采用速度/加速度反馈校正方法拓宽动基座车载雷达天线自动调平平台液压伺服系统的带宽。◆在对静基座自动调平平台Stewart型并联支撑机构运动学反解及自动调平支撑机构单通道液压伺服系统特性研究与分析的基础上,提出采用滑模变结构控制方法对静基座车载雷达天线调平平台控制系统进行设计,并对控制系统的稳定性进行分析;为解决自动调平系统参数不确定性及抑制滑模变结构控制系统抖振现象,本文提出采用带观测器的滑模变结构控制方法对静基座车载雷达天线自动调平平台控制系统进行设计,从而有效地提高了自动调平平台调平性能,减小自动调平系统的稳态误差,有效抑制了滑模变结构控制系统的抖振现象。◆控制系统的响应频率和运行环境的随机性是影响动基座车载雷达天线自动调平性能的两个主要因素,控制系统的响应频率主要由外围设备(液压伺服系统的响应频率、电气系统等)、车速及所采取的控制策略所决定。实际工作过程中,液压伺服系统响应具有一定的频带,盲目提高液压伺服系统的响应频率和提高电气系统的灵敏性是不可取的。本文针对动基座车载雷达天线自动调平系统,提出采用具有随机干扰信号的变结构广义预测控制策略,建立路面随机路谱并将其作为广义预测随机变量序列,引入辅助控制量使广义预测控制与变结构控制相结合,确定车速、控制系统响应频率及随机路谱三者之间的相互联系,实现动基座自动调平平台机动实时调平。更多还原

【Abstract】 This paper presents a 4-DOF parallel manipulator (4-SPS(PS)) and 6-DOF Parallel manipulator (Stewart platform) as the support mechanism of motion and static base for automatic leveling system of vehicle-borne radar antenna, and the kinematics and dynamics of parallel manipulator are analyzed. On this basis, the two different application situations are considered which real-time leveled by the motion base and heavy-load by the static base, the automatic leveling Platform Control System Design and automatic leveling closed-loop control are simulated by the sliding mode variable structure control with observer and the generalized forecast control of variable structure based on the stochastic forecast model are simulated comparably. Details are as follows:Based on the analysis of the leveling characteristics of traditional leveling platform, the article uses the four-DOF parallel manipulator (4-SPS(PS)-type)and 6-DOF Parallel manipulator (Stewart platform) as the support mechanism of motion and static base for automatic leveling system of radar antenna, and the characteristics of posture, kinematics, dynamics and other aspects are analyzed and researched. Based on the SimMechanics, the parallel support mechanism is put to test. The multi-channel hydraulic servo system of Parallel support mechanism which of the static base for automatic leveling system of vehicle-borne radar antenna(Stewart platform)is decoupled by the linear feedback method of decoupling. The sub-chain driver force and the driver speed for parallel support mechanism of motion and static base are analyzed. It is for the lectotype of driver. Under the conditions of open loop, the leveling properties of the support mechanism of motion and static base for automatic leveling system of vehicle-borne radar antenna are analyzed.According to the high degree of accuracy, high frequency band and fast response of the automatic leveling system of vehicle-borne radar antenna, this article uses electro-hydraulic servo system as the driver set of the support mechanism of motion and static base for automatic leveling system of vehicle-borne radar antenna. Based on the in-depth analysis of electro-hydraulic servo system structure, this article established a mathematical model of non-symmetrical cylinder valve-controlled hydraulic servo system. The electro-hydraulic servo system open-loop frequency response characteristics of static base for automatic leveling system of vehicle-borne radar antenna is analyzed, and the temporal response characteristics and frequency response band width of electro-hydraulic servo system which of motion base for automatic leveling system of vehicle-borne radar antenna is analyzed. According to using the feedback correcting method of speed/acceleration, this article broadens electro-hydraulic servo system which of motion base for automatic leveling system of vehicle-borne radar antenna bandwidth.On the basis of the anti-problem of static base for automatic leveling system kinematics and the characteristic test of automatic leveling system single-hydraulic electro-hydraulic servo system, It Suggested that the static base for automatic leveling system of vehicle-borne radar antenna and control system stability are designed by the sliding mode variable structure control. In order to solve the parameter uncertainty of automatic leveling system and inhibit the buffeting phenomenon of sliding mode variable structure control, this paper proposes that the static base for automatic leveling system of vehicle-borne radar antenna is designed by the sliding mode variable structure control with observer. Thereby it can effectively improve the automatic leveling-platform performance, reduce the steady-state error of automatic leveling system, and inhibit the buffeting phenomenon of sliding mode variable structure control.The response frequency of Control System and the randomness of operating environment is two impact of the performance of motion base for automatic leveling system of vehicle-borne radar antenna. The control system of response frequency is determined mainly by the external equipment (frequency response of hydraulic servo system, electrical systems, etc.), speed and the control strategy. In actual work process, hydraulic servo system response shall have a certain frequency bands. Blindly improving the frequency response of hydraulic servo system and improving sensitivity of electric system is not advisable. By using generalized predictive variable mechanism control strategy of a random interference signal, establishes random road spectrum as a random variable sequence of generalized forecasting, introduces auxiliary control value to combine the generalized predictive control with variable structure control ,determines the relationship of speed, response frequency of control system and random road spectrum, achieves the motion base for automatic leveling system real-time leveling.更多还原