【作者】 范金华；

【导师】 吕鸣；

【作者基本信息】 国防科学技术大学 ， 控制科学与工程， 2007， 硕士

【摘要】 舵机加载系统用于模拟航弹舵系统负载和检测舵机性能,是航弹半实物仿真系统的重要组成部分。随着航弹飞行性能的提高,舵系统的发展,对负载模拟技术提出了更高要求。电动式加载系统是近几年研究的热点,许多问题有待研究。本文正是以电机作为动力设备开展了对舵机加载系统的研究工作。论文首先总结了加载技术的进展情况,并指出加载系统中存在的几个基本问题。然后根据系统指标要求,分别从系统结构及模型、分析、控制三个方面对系统进行深入的理论分析和仿真研究。论文给出舵机加载系统的基本结构,分析其工作原理,并建立系统数学模型。根据系统局部参数调整的需要,提出在系统结构中加入弹簧杆和惯量盘,并分析了这两部分结构参数在系统性能调节和多余力补偿器实现中的重要作用。由于稳定性是系统正常工作的基本要求,机械谐振特性制约着系统加载频宽,论文从机械谐振特性和系统稳定性出发,提出了确定弹簧杆刚度和惯量盘转动惯量的取值范围的方法,并指出在一定条件下系统能够开环稳定工作。针对舵机运动引起的多余力对系统性能的影响,基于结构不变性原理,分别以舵机转速、直流电机转速和舵机控制指令信号为观测量,给出了三种多余力补偿方法。由于最优控制具有方法简单、便于工程实现等特点,论文研究了最优控制在舵机加载系统中的应用。针对线性二次型工程近似最优控制中存在的稳态误差问题,提出在最优控制中引入积分控制,并分别用传递函数和状态空间模型实现。针对系统响应速度问题,根据调节时间与极点实部的关系,在二次型性能指标中加入期望衰减度调节系统的响应速度。针对舵机加载系统中存在的非线性、参数时变等不确定因素,以及工程近似最优控制中解的近似性和鲁棒性差等不利因素,研究了鲁棒跟踪与干扰抑制方法在加载系统中的应用。该方法专门针对具有确定性扰动的跟踪系统提出来,能使系统渐近跟踪参考输入的同时抑制确定性扰动对系统性能的影响,而且对系统参数变化引起的扰动的抑制能力强,很适合舵机加载系统。论文阐述了该方法的基本原理,并设计了系统控制器。考虑到基于传递函数方法求解的困难性和精确性,提出将鲁棒跟踪与干扰抑制方法在状态空间中实现。根据鲁棒渐进调节器的基本原理,结合最优控制方法,成功地将鲁棒跟踪与干扰抑制方法应用到舵机加载系统中。鲁棒跟踪与干扰抑制方法是基于内模原理的,对输入信号的精确性和控制器实现的精度有很高要求,而且控制器参数与输入信号频率相对应,当信号频率发生变化时,控制器参数会改变,给系统设计带来了不便。变结构控制能够利用滑动模态使系统具有对干扰的自适应性,利用到达条件使控制结构灵活多样,为工程设计问题提供更多可能性,是不确定系统常用的方法。论文提出了一种设计变结构加载系统的方法,指出引入积分策略增广系统状态方程后再设计变结构控制律。仿真结果表明了该方法的有效性,抑制了多余力的影响,提高了系统跟踪精度。系统控制律设计时,利用了最终滑动模态构造最优滑模面,并采用指数趋近律使系统渐近稳定。该方法解决了传统的变结构控制方法多余力抑制性能差的问题。而且由于只针对一级滑动模态进行设计,构造的变结构系统并不复杂。在实际应用中,由于机械、电气等方面的惯性使理想的开关特性不能满足,变结构控制系统不可避免地会存在抖振问题。考虑到结构不变性原理能有效抑制多余力,同时希望多余力补偿器能够适应系统参数的变化,论文提出一种构造自适应多余力补偿器的方法。这种方法通过构造合适的前馈控制器,结合常规的模型参考自适应控制方法,选取适当的李亚普诺夫函数,运用李亚普诺夫稳定性定理证明了系统的渐进稳定性,得到自适应律,使系统控制器具有自适应性。仿真结果表明,该方法有效抑制了多余力,系统跟踪性能良好。更多还原

【Abstract】 The actuator loading system used to simulate the aerodynamic load of the aerobomb actuator system and test performance of the actuator is the important part of aerobomb hardware-in-the-loop(HIL) simulation. With the development of aerobomb flight performance and actuator system itself, it becomes more necessary to investigate the actuator loading system to improve its performance. The electronic loading system which is based on the electric driving equipment is widely researched in recent years, but there are still many problems remained to be studied. The dissertation’s main task is to explore these problems and give solutions to them.The dissertation first gives a summarization to the development of the loading technology, and discusses several basic problems in the loading system. Then, the theory analysis and simulation research of the actuator loading system is made in detail from three aspects of system structure, analysis and control, to meet the demands of the target.The basic structure of the actuator loading system is presented, and its working principle is described, then its mathematical model is established. For the convenience of adjusting the local parameters of system, the spring staff and the inertia simulator are added into the structure of system. The great role of these two parts is analyzed, especially in the system performance adjustment and the realization of the extraneous compensator.The rigidity range of the spring staff and the inertia range of the inertia simulator are given by means of analyzing system mechanical resonance and stability of the loading channel, considering that the stability is the basic requirement for system to work well and the loading bandwidth of system is restricted by the mechanical resonance. The dissertation indicates that the loading system can work stably in open-loop given some conditions. Confronted with the extraneous torque impacting the system performance, three kinds of compensation methods are provided, based on the structure invariable principle. They are differentiated by observable variables, namely actuator velocity, DC motor velocity and actuator system control signal.The optimal control method is applied to the actuator loading system, because of its advantages of simpleness and easy realization in practical engineering. Confronted with the steady-state error in approximate linear quadratic optimal tracking, the integral strategy is presented, and two methods are used to realize it, separately based on the transfer function and the state space. Finally, the decay rate is added to the cost function to improve the response speed, according to the relationship between the selecting time and the real part of pole.Considering the uncertainty of nonlinearity and parameter variation in the actuator loading system and the disadvantages of approximate solution and bad robustness in applied optimal control method, the robust tracking and disturbance rejection method is studied. It is brought forward for the systems with certain-form disturbance signals, and applying the control method to the actuator loading system is reasonable, for it can asymptotically track reference input and reject the disturbance, and simultaneously make system be adaptive to parameter variation. Its basic principle is described and applied to the actuator loading system based on its transfer function model. Considering the difficulties in getting exact solution, the dissertation gets the robust tracking and disturbance rejection method to be realized in the state space. By incorporating the optimal control method, based on the basic principle of robust asymptotic regulator, the robust tracking and disturbance rejection method is applied to the actuator loading system successfully.The robust tracking and disturbance rejection method is based on the internal mode principle, and has high demands for the accuracy of input and controller realization. Also, the controller is corresponding to the input. When the frequencies of input changes, the controller parameters have to be changed, which brings inconvenience for system design. So, it is necessary to find other robust control methods. The variable structure control is commonly used in systems with uncertainty, for it can not only use sliding mode to make system to be adaptive to disturbance, but also provide many possibilities for engineering design with reaching conditions making control structure flexible and multiple. The dissertation provides a method for constructing the variable structure loading system, and indicates that the variable structure control law should be designed after adopting the integral strategy to enlarge system state space. The simulation results indicate that the method is quite effective in eliminating the extraneous torque and improving the tracking accuracy. In the process of the control law design, the final sliding mode is used to construct the optimal sliding surface, and the exponential reaching law is adopted to make system asymptotically stable. The method solves the problem of bad performance in rejecting the extraneous torque existed in traditional variable structure system. The constructed variable structure controller is simple , because the final sliding mode is just one-order sliding mode.In practical application, the ideal switch characteristic which is required by variable control system is impossible to get, so the wobble problem is inevitable, which may impact system performance. Considering the validity of structure invariable principle in eliminating extraneous torque and the requirement of adaption to parameter variation, the dissertation provides a method to make the extraneous torque compensator adaptive. Based on the model reference adaptive control (MRAC) method, by constructing proper feedforward controller and Lyapunov function, and applying Lyapunov stability theorem in proving system asymptotically stability to get adaptive control law, the method constructs an adaptive control system. The actuator loading system with this kind of adaptive control method can get highperformance by numerical simulation.更多还原