Researches on Fuzzy Creep Compensation of Load Cell

Creep is a critical specification of load cell. Based on the analysis of creep, a new compensation technique, fuzzy creep compensation, is presented in this paper. It firstly introduces the fuzzy recognition to determine loading situations. Compared to the other compensation methods, fuzzy creep compensation can avoid the complicated modeling of creep performance, and it is also proved to be an efficient and simple approach to improve the accuracy of load cell by experiments.

Force Control Compensation Method with Variable Load Stiffness and Damping of the Hydraulic Drive Unit Force Control System

Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit（HDU）, and the contacting between the robot foot end and the ground is complex and variable, which increases the difficulty of force control inevitably. In the recent years, although many scholars researched some control methods such as disturbance rejection control, parameter self-adaptive control, impedance control and so on, to improve the force control performance of HDU, the robustness of the force control still needs improving. Therefore, how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper. The force control system mathematic model of HDU is established by the mechanism modeling method, and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived, considering the dynamic characteristics of the load stiffness and the load damping under different environment structures. Then, simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform, which provides the foundation for the force control compensation experiment research. In addition, the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping, under which the force control compensation method is introduced, and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment. The research results indicate that if the load characteristics are known, the force control compensation method presented in this paper has positive compensation effects on the load characteristics variation, i.e., this method decreases the effects of the load characteristics variation on the force control performance and enhances the force control system robustness with the constant PID parameters, thereby, the online PID parameters tuning control method which is complex needs not be adopted. All the above research provides theoretical and experimental foundation for the force control method of the quadruped robot joints with high robustness.

A NEW HYSTERESIS COMPENSATION METHOD FOR LOAD CELLS

A new hysteresis compensation method is presented.After analyzing the characteristics of strain-gage based load cells under loading & unloading conditions, mathe-matical models are established.A solution to compensate the hysteresis of the load cell by the experiments.It is shown that the method is reliable and can effectively re-duce the hysteresis.

Load compensation research on twicetension for loop anchor cable of inner lining in Yellow River-crossing tunnel

The load compensation equipment for anchor cable named low retraction prestressed anchorage system with twice-tension(referred to as twice-tension anchorage system) is proposed in the paper. Calculation results of loop anchorage prestressing loss(PL) values of inner lining(IL)in Yellow River-crossing tunnel under two anchorage systems,including twice- tension anchorage system and HM(Chinese transliteration is huanmao)anchorage system,are introduced. The software ANSYS is selected to realize the three-dimensional(3D) finite element modeling to accomplish simulation and calculation works under the two anchorage systems,respectively. Stress processes of IL under the two working conditions,of which one is completed cable tensioning(CCT) and the other is water in the tunnel with the designed water pressure(DWP),are contrasted and analyzed. Impacts of prestressing forces of anchor cables on structural safety under the two anchorage systems are contrasted. The calculation results show that the twice-tension anchorage system can reduce PL effectively and then increase prestresses of wall concrete(WC). Meanwhile,the anchorage system has the advantages of improving security and stability of tunnel structure,reducing project costs and saving steel consumption. The research work is available to related design and construction of anchor cable,and is worthy of promotion and application.

Experimental Comparison Between PID Control and Friction Compensation Control for a Class of Nonlinear System with Friction

A point to? point positioning control of systems with highly nonlinear frictions is studied. In view of variable frictions caused by the changes of load torque, an experimental comparison was made between the valve? controlled hydraulic motor servo system with PID control and that with friction compensation control. Experimental results show that the gross steady errors are caused by frictions when the system is controlled by the conventional proportional control algorithm. Although the errors can be reduced by introducing the integral control, the limit cycle oscillation and the long setting time are caused. The positioning error for a constant load torque can be eliminated by using fixed friction compensation, but poor positioning accuracy is caused by the same fixed friction compensation when the load torques varies greatly. The dynamic friction compensation based on the error and change in error measurements can significantly improve the position precision in a broad range of the changes of load torque.

Study on topographic compensation model of the Okinawa Trough Ⅱ. Geological interpretation of isostatic response function of the Okinawa Trough

Based on regional compensation model and experimental isostasy, the isostatic response function of the Okinawa Trough is calculated by using gravity and topographic data. The results are shown as follows: the effective elastic thickness of the plate and compensation depth in the southern Okinawa Trough is obviously greater than those in the middle Okinawa Trough. In reference with other geological and geophysical data, the differences between the two portions are explained to be caused mainly by their differences in temperature of the lithosphere and the compensation mechanism.

Study on topographic compensation model of the Okinawa Trough I. Calculation of theoretical isostatic response function

Based on regional compensation and experimental isostasy, the calculating formula of theoretical isostatic response function is deduced when the loads on top correlate with loads from below. A variety of curves of theoretical isostatic response function were calculated with different effective elastic thickness of the plate and by using different proportions between loads on top and loads from below. And preliminary discussion is made on shapes of the curves.

Research on frequency-temperature compensated sapphire-SrTiO_3 loaded cavity for hydrogen maser

To obtain frequency-temperature compensation in a sapphire loaded cavity for hydrogen maser, a dielectric named SrTiO3 is employed whose temperature coefficient of permittivity is opposite to that of sapphire. Based on theoretical analysis and computer simulation, a TE011 mode of a sapphire loaded cavity associated with two small rings of SrTiO3 with different thickness is solved, and the useful parameters that influence the temperature coefficient of cavity are calculated. Finally an experiment is brought forward and its results are very close to the computing results. When the thickness of SiTiO3 dielectric is 7 mm and the diameter is 17 mm in configuration b, the temperature coefficient of cavity is decreased from -58.8 kHz/K to -8.2 kHz/K and the quality factor is 40248.

Deign of a Synchro-compensation Control System for Elimination of Disturbance

To counter the strong disturbance caused by the rotation of steering axle, a synchro-compensation methodis proposed to absorb the generated disturbance now by driving the loading motor stator to make it synchronously rotatewith its axle. Through analyzing and discussing different kinds of synchro-compensation schemes, the determinedpassive position and speed synchro-compensation systems are designed and simulated by computer. The results prove thatthisa method is effective to eliminate the strong disturbance of the steering axle.

含电动汽车和光伏的配电网演化动态博弈调度策略

针对大规模电动汽车的无序充电行为可能导致电网出现的三相不平衡问题,基于演化动态博弈模型,提出一种考虑三相负荷平衡和光伏消纳的电动汽车充电调度策略。首先,基于电动汽车接入时段的主观性以及光伏出力和负荷的不确定性,引入游牧集群和定居集群之间的演化动态博弈方程;然后,考虑用户侧和电网侧双方利益关系,设计以最小化电动汽车充电费用、三相负荷不平衡度和无功需求为目标的调度优化模型;最后,通过对某商业区配电网算例进行仿真求解,对比分析三相有功曲线、三相无功曲线以及荷电状态曲线的变化趋势。算例结果表明,该调度策略可有效降低三相不平衡度,满足无功补偿的需求以及改善用户充电成本。

基于刚度可调的气动位置伺服系统摩擦补偿控制

气动伺服系统的低刚度、低气源压强、流量易饱和等特性,导致系统在工作过程中能量耗散较大,系统易受摩擦影响,且补偿效果不明显。尤其是当系统的运动方向改变时,会产生明显的“平顶现象”,严重影响气动伺服系统的跟踪精度。采用负载口独立控制结构,消除因两腔耦合而导致的能量耗散,使系统流量特性尽可能地位于线性区间;针对气动系统中存在的摩擦中部分参数不确定,以及外界干扰、动态负载的不确定性,设计非线性自适应鲁棒控制方法;将系统的刚度调节与自适应鲁棒控制进行协同控制,提高气动位置伺服系统的动态性能。仿真和实验结果均表明:具有刚度调节的自适应鲁棒控制能够明显降低系统能量耗散,提高系统位置跟踪精度,有效改善摩擦引起的“平顶现象”。

机器视觉系统中光源位移误差分析与优化

为了采集多类型工况的图像,扩大神经网络的学习样本。改变光源的高度能显著影响图像的差异,为此对影响光源位移准确度的步进电机和驱动结构进行误差分析并提出对应的优化补偿方法。经由对四台步进电机所需负载分析研究,建立负载模型,优化负载驱动电路。针对传动结构中轴心定位误差以及丝杆应力的干扰分别设计优化方案并完成对整体方案的验证。实验表明优化方法能有效地减小装置误差,四组传动丝杆的定位精度分别提升了88.896%、98.336%、45.081%、31.479%,优化效果明显,为图像采集提供位移精度保证。

结构刚塑性动力解的弹性补偿

近年来,我国学者以膜力因子法和饱和分析方法相结合为理论工具,对梁、板等结构件在脉冲载荷作用下的塑性大变形行为作了全面深入的研究,为脉冲加载下结构的最终挠度提供了优于历史上各种刚塑性近似解的最佳刚塑性预测公式。然而,由于实际工程应用中金属结构弹塑性动力响应的复杂性和数值模拟的局限性,与考虑材料弹性效应的结果相比,刚塑性解对脉冲加载下结构所预测的最终挠度的误差有多大,是一个亟待解决的关键问题。对这个问题的首阶段研究成果厘清了材料弹性对脉冲加载下结构塑性动态大变形的影响,定量评估了由最佳刚塑性理论解与弹塑性数值模拟得到的最终挠度预测结果之间的差异。在此基础上,提出了补偿弹性效应的策略和方法,即:在已有的最佳刚塑性解预测的挠度基础上添加一个补偿项,将补偿项表达为脉冲载荷强度的效应与结构自身刚度的效应分离的变量函数,并尽量减少待定系数/指数的数量,以求表达式的简洁;根据这些原则在金属结构的主要工程应用领域内选定结构刚度和外载参数的变化范围,对固支梁和固支方板的案例实施拟合与补偿,最后得到了对梁和板增添补偿项后的简单而实用的最终挠度预测公式,其相对误差在3%的范围之内,很适合工程设计应用。文末列表给出了符号与公式的一览,并对梁和方板的结果作了综合和比较。

宽范围负载CL-LDO的设计

针对规模与功耗骤增的集成电路发展趋势,设计了一种可以提供宽范围负载电流的无片外电容型低压差线性稳压器(CL-LDO).为了解决宽范围负载电流与无片外电容等需求所带来的稳定性问题与瞬态特性问题,提出了动态零点补偿的方式与瞬态增强电路结构,既保障了整体电路在全负载范围内保持稳定,又实现了较好的瞬态特性.基于0.11μm CMOS工艺,完成电路设计、版图设计与仿真,仿真结果表明,在0~500 mA的负载范围内,整体环路增益可以达到68 dB;最小相位裕度为56°;当负载电流在1~500 mA之间发生跳变时(Δt=500 ns),输出过冲和下冲分别为56 mV和141 mV,建立时间分别为2μs和0.78μs;PSR为-67.2 dB@1 kHz,负载调整率为0.137μV/mA.

基于“先无功–后有功”功率补偿的配电网电压协同控制策略

整县分布式光伏电源的大量开发与利用及分布式电源规模化并网对实现“碳达峰、碳中和”与“乡村振兴”两大国家战略具有重要的现实意义。由于分布式电源发电尖峰和低谷阶段与负荷峰谷时常不同步,进而导致配电系统过/欠电压问题,严重影响了电能质量,甚至威胁系统安全。针对上述问题,本文提出一种基于“先无功–后有功”功率补偿的配电网层级式电压协同控制策略。首先,建立基于“先无功–后有功”功率补偿的配电网层级式电压协同控制框架。其次,结合多微电网节点注入电流与电压的方程与功率–电压灵敏度分析,根据多节点电压越限程度,提出一种基于“先无功–后有功”功率补偿的多智能体协同调节策略,该策略先通过无功补偿器进行无功调节,当电压尚未得到有效治理时,再采用多微电网进行有功调节。再次,为了进一步满足各节点微电网有功功率调节需求,并考虑电网内部源–荷–储运行成本与污染排放,提出一种基于多目标优化的微电网内部分布式源–荷–储优化协调功率控制策略。最后,在MATLAB平台中设计了3种仿真场景以及IEEE测试系统模型对所提控制策略进行了验证。结果表明,所提出的电压协同控制方法在最经济的情况下可以实现各节点电压的综合高效治理,同时,所提出的微电网优化协调功率控制策略能使源–荷–储在绿色经济的供电模式下实时精准地满足电压治理目标下微电网有功调节的需求。仿真实验结果验证了本文所提控制策略的有效性。

机械臂负载移动性能与运动调控研究

工业的不断发展对机械臂的负载要求越来越高,而负载的增加会对机械臂末端的精度造成影响.本文以Franka七轴串联机械臂为对象,采用M-DH法和雅可比迭代法对其正、逆运动学展开分析;采用三次函数插值法进行关节空间的轨迹规划.基于拉格朗日方程建立了机械臂的动力学模型,并通过Admas和Simulink联合动力学仿真验证了动力学模型的有效性.最后基于定位控制,对末端位置误差收敛速率、负载质量、控制参数之间的关系展开研究.

基于双人零和博弈的孤岛微电网有界L2增益负荷频率控制

针对含不确定建模误差和新能源接入的孤岛微电网,提出了一种结合有界L2增益基线控制和扰动补偿的综合负荷频率控制(LFC)方法。首先,推导了微电网的全驱模型,将建模误差和新能源的影响总结成一个综合扰动。为提高系统的鲁棒性,该综合扰动被定义成控制信号的对手玩家。进一步,关于扰动抑制的有界L2增益问题被等价成求解综合扰动和控制信号的零和博弈Nash均衡,由此推导出有界L2增益基线控制器。为改善频率的二次控制,设计了基于五阶广义积分观测器的扰动补偿控制,并在此基础上引入了一种针对发电速率约束(GRC)的新型抗发电速率约束(anti-GRC)措施。最后,搭建了16 MW的新能源-柴油混合微电网仿真模型,并在多种工况下对所提出的综合LFC方法进行测试,验证了其有效性。

转台负载工况下角位置误差补偿方法研究

负载会影响转台回转轴的运动状态,进一步影响转台角位置误差的大小。通过分析负载工况下转台角位置误差傅里叶阶次的变化情况,提出一种基于谐波补偿的误差补偿方法。首先,分析负载对转台回转轴的影响,建立回转轴误差运动与角位置误差之间的数学模型,并进行数值仿真;其次,通过负载变化影响回转轴误差运动的大小,获取转台不同负载下的自校准曲线,采用傅里叶法分析对负载变化敏感的傅里叶阶次;最后,选取对负载变化敏感的傅里叶阶次拟合谐波补偿函数对转台角位置误差进行补偿。误差补偿后转台在不同负载工况下的角位置误差最大为±0.25″,与补偿后空载工况下角位置误差相差±0.03″,有效减小了负载对转台角位置误差的影响。

一款400μm^(2)用于极短距离接收机具有中频补偿的56 Gb/s PAM4反相器型连续时间线性均衡器

高速极短距离有线数据接口是芯粒间互连的重要技术方案。传统的基于电流模逻辑的连续时间线性均衡器由于高电源电压和无源器件的使用已经无法满足芯粒间数据接口高密度、小型化、低功耗的需求。针对该问题,本文提出了一种带中频补偿的反相器型连续时间线性均衡器,可在极短距离应用中传输28 Gb/s非归零信号以及56 Gb/s四电平脉冲幅度调制信号。本设计采用28 nm CMOS工艺实现,核心面积仅为400μm^(2)。经过-9.4 dB@14 GHz的极短距离信道后,基于版图的仿真结果表明,所提出的连续时间线性均衡器使28 Gbaud的非归零信号与四电平脉冲幅度调制信号眼宽分别提升0.14 UI与0.41 UI,眼高提升328 mV与119 mV,56 Gb/s四电平脉冲幅度调制信号工况下功耗为6.12 mW。

串联式混合动力车辆动力单元载荷补偿策略研究

为解决串联式混合动力车辆动力单元突加重载时发动机转矩负荷率过高导致运行异常的问题,设计了一种基于模糊控制的载荷补偿策略,通过控制发电机转矩来调节发动机转矩负荷率,避免发动机在临界条件工作。仿真和试验结果表明,该策略有效改善了动力单元工作特性,使其可以稳定平滑地过渡到预期工作点,提高了动力单元工作的鲁棒性。