机载光电平台转动惯量耦合自校正干扰抑制控制研究

针对机载光电平台两轴四框架结构框架间的耦合作用严重影响控制精度的问题,对各框架转轴转动惯量耦合关系进行了研究,对伺服系统控制器进行了改进设计。基于方向转移矩阵与框架间的耦合关系,建立了各框架转轴的转动惯量数学模型,并利用UG软件设计了机载光电平台框架间转动惯量耦合角度变化数据;同时,基于已建立的转动惯量数学模型,结合传统的干扰观测器,在速度控制环PI控制下实现了名义逆模型的实时校正,并设计了改进型干扰观测器。研究结果表明:所建立的转动惯量数学模型正确可靠;改进型干扰观测器能够更准确地估计出等效干扰,使控制回路能够更有效地进行控制。     

采用复合控制提高机载光电平台的数引跟踪精度

简述了机载光电平台的工作原理与功能,介绍了平台速度环和跟踪位置回路的经典控制方法.从提高系统的跟踪精度出发, 提出了复合控制在机载光电平台数引跟踪中的应用.介绍了前馈控制的原理和局限性以及在光电平台数引跟踪回路中的具体设计方法,并给出了实验结果.结果表明,与没有进行复合控制相比较,对机载光电平台实施前馈复合控制能够在不改变系统闭环稳定特性的前提下,将系统的数引跟踪精度提高10%.     

机载光电平台球罩的视轴指向误差

摘要:机载光电平台光学镜头前的通光窗口,多选用内外球心重合的等厚球形玻璃球罩。球罩在加工过程中产生内外表面球心不重合,会给视轴指向精度带来附加误差。本文根据光路图推导出了产生这种误差的数学表达式,分析了内外球心偏离对视轴指向精度的影响。实验结果表明,实测数据与数学推导结果吻合得很好。当某型号球罩的内外表面球心沿视场中心线的偏离达到0.26mm时,45视场处的视轴指向误差实测值达到0.075,超出了0.029（0.5mrad）的允许值。为了将球罩加工误差带来的视轴指向偏差减小到0.017（0.3mrad）,内外球心偏离必须控制在0.10mm以内。     

考虑安装基座影响的光电平台等价捷联惯性稳定控制

采用陀螺仪直接测量光电平台内部载荷的惯性角速度构建反馈,可以在运动载体上控制视轴惯性角速度,实现稳定成像。陀螺捷联惯性稳定控制能够构建前馈,有效提高系统带宽、减小控制误差,但对陀螺安装位置有要求。本文提出了在陀螺直接反馈的机械安装条件下等价捷联稳定的控制方法,并考虑平台基座约束条件建立了动力学模型。该模型显露了光电平台基座安装刚度引入的谐振问题。针对被控对象中的一对谐振和反谐振环节,基于稳定的零极点对消设计滤波器消除谐振。综合利用陀螺直接测量的框架惯性角速度和编码器测量的机械框架相对转角构建等价捷联惯性稳定回路。在等价捷联惯性稳定回路中,采用内回路干扰抑制结合基于逆模型前馈的复合控制方法,有效拓展控制带宽,提高对指令的跟踪精度和对载体姿态晃动的隔离性能。仿真和实验结果表明:该方法有效抑制了安装基座弹性约束力矩的谐振,且与陀螺直接反馈控制相比性能更优。对幅值为1(°)/s、频率为1 Hz的典型正弦角速度指令进行跟踪,均方根误差由1.75(°)/s减小到0.23(°)/s,在1 Hz处扰动隔离度由18%减小到2%。     

机载光电稳定平台检测技术的研究

给出了机载光电稳定平台的检测技术及方法,并提出了一种动态靶标的结构方案及原理,使其能够进行静态、动态的参数测试,尤其是可见光和红外成像系统同时工作时各种参数的测试。在此基础上为建立测量基准的传递方法、形成系统的光电侦察平台总体检测技术提供必要的准备和基础。着重阐述了机载光电稳定平台的静态、动态时的角度测量方法,首次提出了一种利用光线对接方法,实现可见与红外同时测量。还提出了一种数学计算方法,通过两个角度的测量和空间矢量法计算,得出动态靶标的空间坐标,以此作为机载光电稳定平台的指向坐标的真值,并给出了动态靶标的静态与动态精度的标定方法。     

机载光电平台中采用复合控制提高数引跟踪精度的研究

简述了机载光电平台的工作原理与功能,介绍了平台速度环和跟踪位置回路的经典控制方法,从提高系统的跟踪精度出发, 提出了复合控制在机载光电平台数引跟踪中的应用。介绍了前馈控制的原理和局限性,及在光电平台数引跟踪回路中的具体设计方法。并给出了实验结果,与没有进行复合控制相比较,结果表明,对机载光电平台实施前馈复合控制能够在不改变系统闭环稳定特性的前提下,提高系统的数引跟踪精度。     

机载光电载荷视轴指向控制技术综述

针对远距离、长焦距、高分辨机载光电成像载荷对提升视轴指向控制精度的迫切需求,从电流、速度、位置三环控制的基本原理入手,对电机的力矩控制、干扰的抑制、对延迟的鲁棒性等问题进行了分析。首先,分析了新型无刷电机电流驱动和控制方法及相应的优缺点。论述了主动抗扰内回路以及速度反馈外回路控制问题,从算法的角度提高对视轴运动速度的控制性能;另一方面,考虑机械结构刚度对控制增益的制约,从两级控制结构的角度对相应的控制方法进行分析。对目标跟踪控制这一典型位置环控制问题进行了分析,从时滞反馈控制的角度论述了相应的理论研究进展。最后,综合当前技术发展趋势给出机载光电载荷视轴指向控制技术的思考和建议。     

机载光电侦察稳定平台系统分析

介绍了机载光电侦察稳定平台的几种框架形式,从稳定原理方面分析了各自的优缺点,并指出随着光电侦察技术及装备的发展,四框架两轴稳定平台系统是最佳的选择方案.     

机载光电侦察平台复合减振设计

为减小振动对机载光电侦察平台成像质量和稳定精度的影响,对光电平台进行了复合减振设计.分析了复合减振原理,针对以往单级隔振系统存在的缺点在平台内框架和外框架之间设计了二级减振系统,更加有效地隔离了外框架传递到内框架上的振动.采用二维参数优化方法计算出了复合减振系统的最优固有频率比fopt为1.43,最优阻尼比ζopt为0...     

光电对抗稳定平台强光能干扰技术研究

本文针对干扰破坏弹类飞行目标的性能,对光电对抗稳定平台强光能干扰系统进行了分析和设计.本系统采用二维精密稳定平台系统来实现了对空中飞行目标进行快速捕获、锁定并自动跟踪,由强光能干扰发射系统发出强光能干扰信号,实现对飞行目标进行干扰及精确打击,以达到保护自己打击敌人的目的.     

航空光电稳定平台的自抗扰控制系统

对航空光电稳定平台模型进行分析并利用电流环简化了平台模型。阐述了影响平台稳定性的扰动及抑制扰动的方法,提出一种基于预报修正的自抗扰控制系统。首先,提出了一种预报修正方法,采用"先预报,后修正"的方法来减小扰动观测值的滞后和超调;然后,设计了基于二阶扩张状态观测器的自抗扰控制系统,对扰动进行线性化动态补偿;最后,在振动平台上对系统进行了速度稳定实验、目标跟踪实验和鲁棒性分析。结果表明,与经典的平方滞后超前控制方法相比,本文设计的控制方法对扰动的隔离度至少提高了5.88dB。另外,设计的系统具有很强的鲁棒性,在系统参数改变±15%的范围内,仍得到很好的控制效果。由于所设计的控制系统具有很强的实用性和鲁棒性,在工程实际应用中提高了航空光电稳定平台的抗扰动性能。     

A novel disturbance-observer based friction compensation scheme for ball and plate system

Friction is often ignored when designing a controller for the ball and plate system, which can lead to steady-error and stick-slip phenomena, especially for the small amplitude command. It is difficult to achieve high-precision control performance for the ball and plate system because of its friction. A novel reference compensation strategy is presented to attenuate the aftereffects caused by the friction. To realize this strategy, a linear control law is proposed based on a reduced-order observer. Neither the accurate friction model nor the estimation of specific characteristic parameters is needed in this design. Moreover, the describing function method illustrates that the limit cycle can be avoided. Finally, the comparative mathematical simulations and the practical experiments are used to validate the effectiveness of the proposed method.     

Combined feedforward and model-assisted active disturbance rejection control for non-minimum phase system

Control of the non-minimum phase (NMP) system is challenging, especially in the presence of modelling uncertainties and external disturbances. To this end, this paper presents a combined feedforward and model-assisted Active Disturbance Rejection Control (MADRC) strategy. Based on the nominal model, the feedforward controller is used to produce a tracking performance that has minimum settling time subject to a prescribed undershoot constraint. On the other hand, the unknown disturbances and uncertain dynamics beyond the nominal model are compensated by MADRC. Since the conventional Extended State Observer (ESO) is not suitable for the NMP system, a model-assisted ESO (MESO) is proposed based on the nominal observable canonical form. The convergence of MESO is proved in time domain. The stability, steady-state characteristics and robustness of the closed-loop system are analyzed in frequency domain. The proposed strategy has only one tuning parameter, i.e., the bandwidth of MESO, which can be readily determined with a prescribed robustness level. Some comparative examples are given to show the efficacy of the proposed method. This paper depicts a promising prospect of the model-assisted ADRC in dealing with complex systems.     

航空遥感惯性稳定平台齿隙非线性建模与补偿

针对航空遥感惯性稳定平台框架伺服系统中齿隙非线性环节造成的系统驱动延时、换向跳变及冲击振荡等问题,对航空遥感惯性稳定平台齿隙非线性进行建模与补偿.在分析齿隙非线性环节结构和传动特点基础上,建立了齿隙非线性死区模型;利用MATLAB仿真分析了齿隙对系统性能的影响;以框架伺服系统为研究对象,应用反步积分法,通过依次选择Lyapunov函数,设计了基于状态反馈的控制器,并进行实验验证.结果表明:齿隙误差补偿可有效提高系统控制精度;与传统PID控制相比,反步积分法显著降低了齿隙非线性对伺服系统性能的影响,在给定框架期望转角情况下,反步积分法比PID控制响应速度提高78.26％、稳态精度提高23.1％.     

Path following control for towing system of cylindrical drilling platform in presence of disturbances and uncertainties

Towing is a critical process to deploy a cylindrical drilling platform. However, the towing process faces a great variety of risks from a complex nautical environment, the dynamics in towing and maneuvering, to unexpected events. Therefore, safely navigating the towing system following a planned route to a target sea area is essential. To tackle the time-varying disturbances induced by wind, current and system parametric uncertainties, a path following control method for a towing system of cylindrical drilling platform is designed based on linear active disturbance rejection control. By utilizing Maneuvering Modeling Group model as well as a catenary model, we develop a three degree-of-freedom dynamic mathematical model of the towing system under external environmental disturbances and internal uncertainties. Furthermore, we design a linear active disturbance rejection control path following controller for real-time tracking error correction based on a guidance method combining cross-track error and parallax. Finally, the path following performance of the towing system is evaluated in a simulation environment under various disturbances and internal uncertainties, where the corresponding tracking error is analyzed. The results show that the linear active disturbance rejection control performs well under both the external disturbance and inherent uncertainties, and better satisfy the tracking performance criteria than a traditional proportional–integral–derivative controller.     

Adaptive fast sliding mode fault tolerant control integrated with disturbance observer for spacecraft attitude stabilization system

In this paper, the problem of fault-tolerant control (FTC) for spacecraft attitude stabilization system with actuator fault and mismatched disturbance is investigated. A novel fault tolerant control strategy based on adaptive fast terminal sliding mode control (AFTSMC) is proposed. Firstly, a novel composite observer is proposed to estimate the disturbance, actuator efficiency factor and partial states of the system. By introducing a sliding mode observer, the bias actuator fault is reconstructed. Subsequently, in accordance with the estimated information, a novel sliding mode fault tolerant controller is designed. The proposed control scheme contains two compensators and two adaptive parameters to attenuate the mismatched disturbance, to compensate actuator fault, and to guarantee fast convergence of the system. Furthermore, the reachability of sliding motion is proved. The simulation results for the spacecraft system illustrate the effectiveness of the proposed method.     

超磁致伸缩致动器的复合反馈控制及其在变椭圆销孔精密加工中的应用

针对非对称性销孔的镗削加工,研究了用于高负荷孔精密镗削装置的超磁致伸缩致动器(GMA)的相关控制。考虑GMA的迟滞非线性,分析了准静态改进型Prandtl-Ishlinskii(P-I)模型的数学机理;为提高其动态适用频域和控制精度,提出了结合相角前馈补偿的动态改进型P-I模型,获得了满意的控制效果。结合PID反馈控制搭建的闭环控制实验结果显示,GMA的迟滞非线性由补偿前的14.5%~67.2%减小到1.5%~4.3%,有效降低了迟滞系统的非线性误差。在此基础上进行了椭圆销孔试镗削实验,结果显示其椭圆度均符合图纸要求,验证了补偿方法的正确性。本文的研究为实现高负荷异形孔的精密加工提供了新方法。     

Enhanced IMC design of load disturbance rejection for integrating and unstable processes with slow dynamics

In view of the deficiencies in existing internal model control (IMC)-based methods for load disturbance rejection for integrating and unstable processes with slow dynamics, a modified IMC-based controller design is proposed to deal with step- or ramp-type load disturbance that is often encountered in engineering practices. By classifying the ways through which such load disturbance enters into the process, analytical controller formulae are correspondingly developed, based on a two-degree-of-freedom (2DOF) control structure that allows for separate optimization of load disturbance rejection from setpoint tracking. An obvious merit is that there is only a single adjustable parameter in the proposed controller, which in essence corresponds to the time constant of the closed-loop transfer function for load disturbance rejection, and can be monotonically tuned to meet a good trade-off between disturbance rejection performance and closed-loop robust stability. At the same time, robust tuning constraints are given to accommodate process uncertainties in practice. Illustrative examples from the recent literature are used to show effectiveness and merits of the proposed method for different cases of load disturbance.