Real-Time Iterative Compensation Framework for Precision Mechatronic Motion Control Systems

With regard to precision/ultra-precision motion systems,it is important to achieve excellent tracking performance for various trajectory tracking tasks even under uncertain external disturbances.In this paper,to overcome the limitation of robustness to trajectory variations and external disturbances in offline feedforward compensation strategies such as iterative learning control(ILC),a novel real-time iterative compensation(RIC)control framework is proposed for precision motion systems without changing the inner closed-loop controller.Specifically,the RIC method can be divided into two parts,i.e.,accurate model prediction and real-time iterative compensation.An accurate prediction model considering lumped disturbances is firstly established to predict tracking errors at future sampling times.In light of predicted errors,a feedforward compensation term is developed to modify the following reference trajectory by real-time iterative calculation.Both the prediction and compen-sation processes are finished in a real-time motion control sampling period.The stability and convergence of the entire control system after real-time iterative compensation is analyzed for different conditions.Various simulation results consistently demonstrate that the proposed RIC framework possesses satisfactory dynamic regulation capability,which contributes to high tracking accuracy comparable to ILC or even better and strong robustness.

Comparison of delay compensation methods for real-time hybrid simulation using frequency-domain evaluation index

The delay compensation method plays an essential role in maintaining the stability and achieving accurate real-time hybrid simulation results. The effectiveness of various compensation methods in different test scenarios, however, needs to be quantitatively evaluated. In this study, four compensation methods （i.e., the polynomial extrapolation, the linear acceleration extrapolation, the inverse compensation and the adaptive inverse compensation） are selected and compared experimentally using a frequency evaluation index （FEI） method. The effectiveness of the FEI method is first verified through comparison with the discrete transfer fimction approach for compensation methods assuming constant delay. Incomparable advantage is further demonstrated for the FEI method when applied to adaptive compensation methods, where the discrete transfer function approach is difficult to implement. Both numerical simulation and laboratory tests with predefined displacements are conducted using sinusoidal signals and random signals as inputs. Findings from numerical simulation and experimental results demonstrate that the FEI method is an efficient and effective approach to compare the performance of different compensation methods, especially for those requiring adaptation of compensation parameters.

Periodic Error Compensation for Quartz MEMS Gyroscope Drift of INS

In order to improve the navigation accuracy of an inertial navigation system （INS）, composed of quartz gyroscopes, the existing real-time compensation methods for periodic errors in quartz gyroscope drift and the periodic error term relationship between sampled original data and smoothed data are reviewed. On the base of the results, a new compensation method called using former period characteristics to compensate latter smoothness data （UFCL for short） method is proposed considering the INS working characteristics. This new method uses the original data without smoothing to work out an error conversion formula at the INS initial alignment time and then compensate the smoothed data errors by way of the formula at the navigation time. Both theoretical analysis and experimental results demonstrate that this method is able to cut down on computational time and raise the accuracy which makes it a better real-time compensation approach for periodic error terms of quartz micro electronic mechanical system （MEMS） gyroscope＇s zero drift.

TWO NEW TYPES OF MICROWAVE RADIOMETER: A COMPUTER GAIN COMPENSATIVE DESIGN AND A REAL-TIME CALIBRATED DESIGN

Long term stability is the main factor that influences the minimum detectable signal of microwave radiometers. Two new types of microwave radiometer were studied: a computer gain compensative microwave radiometer and a real-time calibrated microwave radiometer. The long term stability of both designs was optimal because they were insensitive to system gain fluctuations. The continuous calibrated microwave radiometer was also insensitive to system noise fluctuations. The minimum detectable signals were 0.13 and 0.19K respectively under an integration time of 0.6s.

A multi-channel real-time digital integrator for magnetic diagnostics in HL-2A tokamak

A novel full-digital integrator has been developed for the magnetic diagnostics in HL-2A. Based on the pipeline processing of the field-programmable gate array and high-speed PCI extensions for instrumentation platform, the digital integrator has realized octal-channel10-k Hz real-time integration and data transmission. In order to reduce the integration drift, a 24-bit analog-todigital converter and simple analog processing circuits are applied for high-precision sampling, while certain correction algorithms are used to minimize the drift. With simple and highly integrated circuits and high-performance digital processor, the digital integrator is of high stability and functional expansibility which greatly simplifies the operation procedure. The digital integrator has been tested in the plasma discharge experiments, and the experimental results have confirmed that the drift performance and accuracy of the digital integrator could fully meet the requirements of HL-2A.

Image Motion Compensation of Off-Axis TMA Three-Line ArrayAerospace Mapping Cameras

To enhance the image motion compensation accuracy of off-axis three-mirror anastigmatic( TMA)three-line array aerospace mapping cameras,a new method of image motion velocity field modeling is proposed in this paper. Firstly,based on the imaging principle of mapping cameras,an analytical expression of image motion velocity of off-axis TMA three-line array aerospace mapping cameras is deduced from different coordinate systems we established and the attitude dynamics principle. Then,the case of a three-line array mapping camera is studied,in which the simulation of the focal plane image motion velocity fields of the forward-view camera,the nadir-view camera and the backward-view camera are carried out,and the optimization schemes for image motion velocity matching and drift angle matching are formulated according the simulation results. Finally,this method is verified with a dynamic imaging experimental system. The results are indicative of that when image motion compensation for nadir-view camera is conducted using the proposed image motion velocity field model,the line pair of target images at Nyquist frequency is clear and distinguishable. Under the constraint that modulation transfer function( MTF) reduces by 5%,when the horizontal frequencies of the forward-view camera and the backward-view camera are adjusted uniformly according to the proposed image motion velocity matching scheme,the time delay integration( TDI) stages reach 6 at most. When the TDI stages are more than 6,the three groups of camera will independently undergo horizontal frequency adjustment. However, when the proposed drift angle matching scheme is adopted for uniform drift angle adjustment,the number of TDI stages will not exceed 81. The experimental results have demonstrated the validity and accuracy of the proposed image motion velocity field model and matching optimization scheme,providing reliable basis for on-orbit image motion compensation of aerospace mapping cameras.

Design to conditioning circuits of dynamic compensation of reactive power in the intelligence voltage controller

The paper introduces one design idea that making use of SCM to control Real-timely the dynamic compensation of reactive power.Firstly,design one Circuit to Sample the voltage and current,and by these datas we can easily calculate the power factor,and Voltage controller in the microcontroller to determine whether input the compensation capacitance according to the size of power factor,the paper also analyzes the principle of capacitance compensation and calculation method. Dynamic compensation for the entire process is quick and accurate.

Real-time compensation of phase drift for phase-encoded quantum key distribution systems

Phase drift is an inherent problem in phase-encoded quantum key distribution(QKD) systems.The current active phase trackingand compensation solutions cannot satisfy the requirements of a system with nonlinearity in phase modulation.This paper presents a four-phase scanning method,which is based on the quantitative analysis of the quantum bit error rate(QBER) from phasedrift and the performance requirements of phase compensation.By obtaining the four interference fringes and adjusting the codingmatrix of the system,this method automatically calculates the accurate driving voltages for the phase modulator.The implementation and experimental tests show that the proposed method can compensate phase drift caused by environmental changes and thesystem's nonlinearity,and is applicable to large-scale QKD networks.

基于PI闭环反馈的EtherCAT分布式时钟漂移补偿优化

接入工业总线的设备的增加会导致高延迟等同步性问题。基于EtherCAT对分布式时钟同步算法进行研究与分析,针对其在漂移补偿过程中存在补偿精度低的问题,提出了一种基于闭环反馈控制思想的动态漂移补偿算法。算法先利用定点数改进本地时钟,再利用PI控制调节漂移补偿值。最后搭建了测试平台,包括基于SOEM实现的主站与基于STM32+FPGA架构实现的从站,优化前后的算法分别在FPGA中实现。测试结果表明:定点数改进的本地时钟分辨率可以达到2^(-20) ns, PI闭环反馈优化后的漂移补偿算法可以将同步误差降低到25 ns之内,明显提高从站之间的同步性能。

高性能铷原子钟的高精度频率漂移补偿研究

铷原子钟可靠性高、体积小、功耗低,在导航、通信等领域被广泛使用.尤其对于导航卫星星载铷原子钟,发展至今具有了优异的稳定度性能,但其固有的频率漂移特性(约E-12~E-13/天)会恶化其长期性能,影响卫星自主守时能力.通过对高性能铷原子钟的频率数据进行充分分析,评估可能导致频率漂移的物理机制,提出一种高精度频率漂移补偿的方案并开展了实验验证.结果表明,在无外部驯服情况下60天内高性能铷原子钟的漂移率可保持E-15/天量级,天稳定度达到E-15量级(Allan偏差),极大提升铷原子钟的自主守时能力.

低温度敏感度谐振式压力传感器设计与仿真

为降低材料杨氏模量温度漂移和热应力对谐振式压力传感器温度漂移的影响,该文设计了一种基于Si-SiO 2复合H形谐振梁和双谐振器结构的低温度敏感度谐振压力传感器。通过有限元仿真软件COMSOL对传感器进行仿真验证。结果表明,在0~350 kPa内传感器灵敏度可达21.146 Hz/kPa,-50~125℃内零点温度漂移低至0.2 Hz/℃。与全硅结构相比,灵敏度温度漂移由339×10^(-6)/℃降低至14.1×10^(-6)/℃,可适应工作温度范围较高的环境。

双目面结构光三重扫描测量系统温漂补偿方法

双目面结构光三重扫描是在条纹投影双目视觉重建的基础上,追加左、右相机与投影仪构成的单目视觉系统重建点云,在反光和凹凸起伏等表面测量应用上具有更好的点云完整性优势。但由于环境温度变化影响,投影仪产生较大温度漂移,导致双目重建点云与单目重建点云发生“分层”现象。为此,文中提出了一种基于正交条纹投影的三重扫描系统温漂在线补偿方法,通过投影仪投射正交条纹来构建双目重建点在投影仪图像中准确的映射关系,并基于双目重建点在投影仪图像中的重投影误差最小化目标函数来求解温漂补偿后的投影仪最优外参数。最后,以金属球和汽车零件作为被测对象进行实验验证,在不依靠标定板等先验信息及繁琐标定流程基础上,所提在线快速补偿方法可以使得双目点云与单目点云温漂量分别减小78.2%和94.3%,极大减轻了温度变化对于三重扫描点云数据拼接影响。

一种采用分段温度补偿的低温漂带隙基准源

提出了一款宽温度范围、低温漂系数的带隙基准源。以Banba结构的带隙基准源作为核心电路,产生开口向下的抛物线状输出基准电压,将抛物线顶点向高温段移动,使输出基准电压的高温段趋于平缓,利用分段温度补偿技术对低温段进行曲率补偿,补偿电流由不同温度系数的电流相减产生,有效降低了温漂系数,并拓宽了带隙基准源工作的温度范围。在0.18μm的标准互补金属氧化物半导体(CMOS)工艺下进行电路性能验证,仿真结果表明,在-50~150℃的温度范围内,提出的带隙基准源的温漂系数为0.65 ppm/℃,在1.8 V的电源电压下输出电压为760 mV,版图面积仅为0.01 mm^(2)。

一种超低失调集成运算放大器的设计与实现

基于双极型工艺设计了一种超低失调集成运算放大器。通过在差分输入级的有源负载处设计电阻修调网络来调整失调电压,并针对基极电流补偿不可控的问题设计了可修调的基极电流补偿结构来降低偏置电流,利用激光修调技术减小基极补偿结构引入的随机失调,有效改善了输入级失调。增益级采用结型场效应晶体管(JFET)差分对管以获得高增益,输出级采用全npn晶体管的乙类输出结构可满足大功率输出需求。芯片实测数据表明:在全温度范围内,失调电压最大为-25.3μV,失调电压温漂为0.025μV/℃,输入偏置电流为-3.535 nA,输入失调电流为-0.825 nA。实现了超低的失调电压、电流和温漂。

采用AD654芯片的直流电压传感器及其温度漂移补偿

提出一种基于电压-频率变换的光电式电压传感器及电压传感信号温度漂移的补偿方法。电压传感系统主要包括电阻分压器、电压-频率变换芯片、发光二极管、光纤、光电探测与信号处理单元等。利用两块AD654型芯片分别作为被测电压和温度传感单元,通过对两路光传感信号进行非线性数据拟合等方式实现了对电压传感信号温度漂移的实时补偿。实验测量了0.6 kV~5.0 kV范围内的直流电压,并实现了电压传感信号的温度漂移补偿,在-40℃~+60℃的温度范围内,电压传感信号温度漂移的平均相对误差约为±0.7%。

电阻焊电流信号积分漂移软件补偿方法

为满足电阻焊电流长时间检测的需求并简化检测电路,针对罗氏线圈信号调理的积分漂移问题,探讨了基于软件补偿的漂移补偿方法。采用多款国产运算放大器构建积分器,在恒电流控制模式下检测积分器输出信号的漂移率,在数据处理过程中叠加漂移率的平均值以实现软件补偿。将积分漂移电压视为电流检测的误差,以相对误差分析了恒电流输出2 s过程中软件补偿的准确性。结果表明,基于软件补偿的漂移补偿方法在信号检测后进行数据修正,减少了对硬件补偿的依赖,在1~4 kA的被测电流范围内相对误差的平均值不超过1.0%,能够满足电阻焊电流长时间检测需求。该补偿方法丰富了基于罗氏线圈的电流信号处理手段,具有较好的工程适用性。

基于改进神经网络的TMR磁传感系统温漂校准方法

由于环境以及自身元件的发热等因素的影响,TMR磁传感系统实际工作温度会发生一定程度的波动。随着温度的升高或降低,TMR磁传感系统的实际输出会产生一定的误差,出现输出的温度漂移现象。为了抑制温度漂移对TMR磁传感系统的影响,采用反向传播(BP)神经网络对系统输出的温度漂移现象进行补偿,并利用遗传算法(GA)对BP神经网络进行优化,通过对补偿前后数据的对比,使TMR磁传感系统的输出温漂大幅下降了2个量级,得到了较为理想的效果,提升了TMR磁传感系统的性能和可靠性。

光电稳定平台瞄准线漂移前馈补偿算法

针对地球自转角速度在光电吊舱俯仰轴上的分量影响稳像模式下激光雷达成像质量问题,提出了一种基于机载惯导系统的前馈补偿算法,根据飞机姿态信息、纬度信息以及设备轴角信息,通过旋转矩阵解算出补偿量并前馈到速度环中,实现对光电稳定平台的瞄准线漂移的补偿。对所提出算法进行了仿真与实验验证,实验结果显示,当俯仰轴朝向南北时,引入该补偿算法后半小时内俯仰角度漂移量为0.231°,小于不加该补偿方法时的6.005°;当俯仰轴朝向北南时,引入该补偿算法后半小时内俯仰漂移量为-0.385°,小于不加该补偿方法时的-5.372°,证明该算法可有效补偿稳像模式下俯仰位置漂移。

Temperature Bias Drift Phase-Based Compensation for a MEMS Accelerometer with Stiffness-Tuning Double-Sided Parallel Plate Capacitors

This paper reports an approach of in-operation temperature bias drift compensation based on phase-based calibration for a stiffness-tunable MEMS accelerometer with double-sided parallel plate(DSPP)capacitors.The temperature drifts of the components of the accelerometer are characterized,and analytical models are built on the basis of the measured drift results.Results reveal that the temperature drift of the acceleration output bias is dominated by the sensitive mechanical stiffness.An out-of-bandwidth AC stimulus signal is introduced to excite the accelerometer,and the interference with the acceleration measurement is minimized.The demodulated phase of the excited response exhibits a monotonic relationship with the effective stiffness of the accelerometer.Through the proposed online compensation approach,the temperature drift of the effective stiffness can be detected by the demodulated phase and compensated in real time by adjusting the stiffness-tuning voltage of DSPP capacitors.The temperature drift coefficient(TDC)of the accelerometer is reduced from 0.54 to 0.29 mg/℃,and the Allan variance bias instability of about 2.8μg is not adversely affected.Meanwhile,the pull-in resulting from the temperature drift of the effective stiffness can be prevented.TDC can be further reduced to 0.04 mg/℃through an additional offline calibration based on the demodulated carrier phase representing the temperature drift of the readout circuit.

一种低温漂的无运放带隙基准电压源

针对传统无运放带隙基准电压源温度特性差的问题,设计了一种低温漂的无运放带隙基准电压源电路。设计中通过电流镜以及环路反馈的方法来代替传统运放对电路进行钳位,避免了运放输入失调电压对带隙基准电压精度的影响。同时基于华虹0.35μm BCD工艺,利用工艺库中温度系数不同的电阻来产生与温度相关的非线性项,从而对三极管负温度系数电压中的高阶非线性项进行补偿,实现了无运放带隙基准的低温漂特性。通过Cadence Spectre对电路进行仿真,仿真结果表明:在-55~125℃温度范围内,输入电压为5.5 V时,带隙基准电压的温漂系数为1.949×10^(-6)/℃;在10 kHz时,电源抑制比达到71.5 dB,在1 MHz时,电源抑制比达到46.3 dB。