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题名:
光电跟踪系统低速平稳性技术研究
作者: 李拥军
学位类别: 博士
答辩日期: 2009-06-05
授予单位: 中国科学院光电技术研究所
授予地点: 光电技术研究所
导师: 杨文淑
关键词: 光电跟踪系统 ; 低速 ; 摩擦力矩 ; LuGre模型 ; 补偿 ; 光电编码器 ; FIR电机波动力矩 ; 自抗扰控制器
其他题名: Study On the Low-Velocity Stability of Opto-electronic Tracking System
学位专业: 信号与信息处理
中文摘要: 随着精密跟踪技术的发展,对光电跟踪系统性能和精度的需求越来越高。而对于应用于深空探测领域的光电经纬仪,其大部分时间工作在低速或极低速的状态下。所以,其低速平稳性是系统跟踪精度得以保证的关键。研究表明,摩擦力矩、测速精度、电机波动力矩是影响光电跟踪转台系统低速平稳性与跟踪精度的主要因素。 本论文首先介绍了摩擦力矩产生机理,各种摩擦力矩的模型,并主要针对非线性摩擦力矩对转台的影响:“爬行”现象,采用PID校正时引起极限环现象等作了定性和定量分析;并将摩擦力矩引入光电跟踪转台系统,着重分析了其对转台系统速度精度和定位精度的影响。 为了克服非线性摩擦力矩对转台系统精度影响,分别采用固定前馈补偿方法、基于观测器的自适应补偿方法、积分反馈补偿方法对其进行补偿,提高系统精度。并着重介绍了积分反馈控制器的设计方法,采用Lyapunov稳定性理论和拉萨尔一般不变性原理加以证明。仿真分析结果表明,这三种方法可以抑制非线性摩擦力矩影响,提高系统低速平稳性和精度。 为了验证摩擦补偿算法真实效果,在实际转台系统中进行验证。首先确定系统参数,采用频域分析方法确定转台系统的转动惯量;并采用时域与频域相结合方法测量摩擦模型的参数。结合测量结果,将固定前馈补偿、基于观测器的自适应补偿方法在DSP中实现,对摩擦进行补偿,补偿前后对比实验曲线表明补偿算法可以有效提高系统低速精度。 另外,由于现有光电跟踪系统一般采用光电编码器测速。在使用绝对式光电编码器差分测速时,会引入差分噪声,对速度信号有极大影响。由于实时控制系统时序要求严格,提出采用具有线性相位的FIR滤波器对差分得到的速度信号进行处理,并采用最小二乘外推,补偿延时。为了提高速度,FIR在FPGA中采用DA(分布式算法)实现。结果表明,在低速场合该方法可以提高速度精度。 电机波动力矩由齿槽效应或电机系统的制造工艺引起,其存在会破坏系统低速平稳性。提出将自抗扰控制技术引入光电跟踪转台系统,抑制电机波动力矩的不良影响。通过合理设计跟踪微分器、扩张状态观测器、非线性状态误差反馈控制器等环节组合成自抗扰控制器,并在带有电机波动力矩的光电跟踪转台系统中进行仿真分析。结果表明,自抗扰控制器可以抑制电机波动力矩的影响,提高系统低速精度。 本论文针对影响光电跟踪转台系统低速平稳性和跟踪精度的三种主要因素,结合工程实际,提出了一些针对性强的思路和方案,为提高系统低速平稳性提供了理论支持和实践参考。
英文摘要: With the rapid development of the fine tracking technology, the requirement for the performance and precision of the opto-electronic tracking system has been improved gradually. Moreover, the opto-electronic theodolites used for deep space detection often work at a low or a very low velocity, so the stability and tracking precision of the opto-electronic theodolite at low speed is a key factor which affects the precision of the entire tracking system. A series of research have proved that the friction moment, measurement accuracy of velocity and motor moment fluctuation are major factors that affect the tracking performance and precision of the opto-electronic system at a low velocity. Firstly, this paper overviews the mechanism of the friction moment, and introduces a series of friction models, and then the impacts (i.e. “stick-slip” phenomenon and the limited cycle induced by PID tuning) of the nonlinear friction moment on the opto-electronic tracking turntable system are analyzed qualitatively and quantitatively. This paper focused on analyzing the effect of the friction moment on the tracking precision of the opto-electronic tracking turntable system in simulation. This paper proposed three methods to compensate the negative effects of the nonlinear friction moment on the turntable system: fixed feedforward compensation, adaptive compensation based on friction moment observer and integral feedback compensation. Integral feedback compensation is proved and anlayzed by using Lyapunov method and Lasalle common invariance principle. Simulation results show that the above three methods all can alleviate the negative effect of friction and enhance the tracking precision. In order to acquire the accurate parameters of the LuGre friction moment model, we measure the moment of inertia of the system, and then measure the parameters of the friction model in time and frequency domain. The above friction compensation methods are implemented by C language based on the DSP, and introduced to the actual turntable system. Some experiment results are presented. Based on the comparative experiment data we can draw the conclusion that the compensation methods can alleviate the effect of the friction moment and enhance the tracking precision especially at the low velocity. Otherwise, the quality of the velocity signal is an important factor which can affect the tracking precision. On condition that the velocity sensor used is absolute opto-electronic encoder and the velocity signal is obtained by position difference, there will be a lot of noise. In order to enhance the quality of the signal, we filter it with FIR filter which is linear phase and the time delay is predictable. The delay is compensated by LS algorithm. The FIR is designed and implemented in the FPGA, which can reduce the time consumption. The results show that this method can enhance the quality of the velocity signal at a low velocity. Motor moment fluctuation which is induced by alveolus effect and manufacturing process can also affect the stability, so the active disturbance rejection control technique is induced into the system to alleviate the negative effect. And the active disturbance rejection controller is composed of tracking differentiator, extended state observer, nonlinear state error feedback controller, and so on. The controller is used on the opto-electronic tracking turntable system with motor moment fluctuation for simulation, and the results show that the active disturbance rejection controller can restrain the motor moment fluctuation, and enhance the tracking precision at low velocity. In this paper, some strategies are put forward to enhance the precision of the opto-electronic tracking system at low velocity. The work of this dissertation can provide some reference to the future development of the opto-electronic tracking system.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ioe.ac.cn/handle/181551/351
Appears in Collections:光电技术研究所博硕士论文_学位论文

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Recommended Citation:
李拥军. 光电跟踪系统低速平稳性技术研究[D]. 光电技术研究所. 中国科学院光电技术研究所. 2009.
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