车载环境下MEMS微镜长期可靠性及控制方法

作为一种新型微光机电系统,MEMS微镜可完成微尺度下的光调控工作,在光电通信、医疗成像、民用投影、雷达探测等领域应用广泛.近年来,以微镜为核心部件的MEMS激光雷达因其体积小和功耗低等优势,有望成为更具竞争力的辅助驾驶传感器之一.然而,鉴于车载应用特殊性,MEMS微镜在温湿、电磁、振动和冲击等复杂多物理场耦合环境下的各类可靠性问题严重制约了MEMS激光雷达的工程应用.本文立足MEMS微镜可靠性研究领域,综述其在高频振动、温湿循环、电磁耦合等极端环境下的分层翘曲、结构断裂、静电吸合、短路烧毁等复杂失效形式及失效机制,总结了MEMS微镜常见动力学建模理论及控制方法,讨论并展望了MEMS激光雷达车规化面临的主要挑战和发展趋势.

三轴MEMS陀螺仪轨迹跟踪的自耦PID控制方法

为了有效提高三轴微机械(Micro-Electro-Mechanic System,MEMS)陀螺仪的抗干扰能力和检测精度,基于自耦PID控制理论提出了一种简单的陀螺仪控制方法。该方法将三轴MEMS陀螺仪控制问题分解为三个严格反馈子系统的控制问题,然后将三个子系统已知或未知动态、其不确定性和外部有界扰动分别定义为三个总扰动,进而将三个子系统等价映射为三个二阶线性扰动系统,据此分别构建了在总扰动反相激励下的三个受控误差系统,并根据自耦PID控制理论分别设计了三个自耦PD控制器,最后分析了每个子系统的鲁棒稳定性和抗扰动鲁棒性。仿真实验证明了所提控制方法的有效性,其在MEMS陀螺仪控制系统领域具有良好的实际应用前景。

Chemical modification of barite for improving the performance of weighting materials for water-based drilling fluids

With increasing drilling depth and large dosage of weighting materials,drilling fluids with high solid content are characterized by poor stability,high viscosity,large water loss,and thick mud cake,easier leading to reservoir damage and wellbore instability.In this paper,micronized barite(MB)was modified(mMB)by grafting with hydrophilic polymer onto the surface through the free radical polymerization to displace conventional API barite partly.The suspension stability of water-based drilling fluids(WBDFs)weighted with API barite:mMB=2:1 in 600 g was significantly enhanced compared with that with API barite/WBDFs,exhibiting the static sag factor within 0.54 and the whole stability index of 2.The viscosity and yield point reached the minimum,with a reduction of more than 40%compared with API barite only at the same density.Through multi-stage filling and dense accumulation of weighting materials and clays,filtration loss was decreased,mud cake quality was improved,and simultaneously it had great reservoir protection performance,and the permeability recovery rate reached 87%.In addition,it also effectively improved the lubricity of WBDFs.The sticking coefficient of mud cake was reduced by 53.4%,and the friction coefficient was 0.2603.Therefore,mMB can serve as a versatile additive to control the density,rheology,filtration,and stability of WBDFs weighted with API barite,thus regulating comprehensive performance and achieving reservoir protection capacity.This work opened up a new path for the productive drilling of extremely deep and intricate wells by providing an efficient method for managing the performance of high-density WBDFs.

基于RBF的MEMS加速度计温控系统设计

针对微机电系统(MEMS)加速度计受到温度变化影响较大、产生不同程度的漂移和测量误差,难以满足工业机器人领域高精度导航的问题,提出一种提高MEMS精度的温度补偿方法。利用热电制冷器设计适用于嵌入式的温度控制系统,使MEMS传感器的工作温度相对稳定。利用MPU6050的MEMS加速度计,设计一种基于STM32主控的嵌入式温度控制系统,并通过上位机采集数据,对比分析改进径向基函数(RBF)、RBF和常规PID等算法的温控效果。结果表明:在当前的PID控制参数的条件下,改进的RBF整定效果相对于RBF-PID和经典PID,在超调量、稳态误差、调节时间等指标上,表现出更优的系统响应和控制精度,超调量降低41.3%,调整时间减低52.3%,系统对温度的控制精度约为0.04℃。

Design and implementation of digital closed-loop drive control system of a MEMS gyroscope

In order to effectively control the working state of the gyroscope in drive mode, the drive characteristics of the micro electromechanical system （MEMS） gyroscope are analyzed in principle. A novel drive circuit for the MEMS gyroscope in digital closed-loop control is proposed, which utilizes a digital phase-locked loop （PLL） in frequency control and an automatic gain control （AGC） method in amplitude control. A digital processing circuit with a field programmable gate array （FPGA） is designed and the experiments are carried out. The results indicate that when the temperature changes, the drive frequency can automatically track the resonant frequency of gyroscope in drive mode and that of the oscillating amplitude holds at a set value. And at room temperature, the relative deviation of the drive frequency is 0.624 ×10^-6 and the oscillating amplitude is 8.0 ×10^-6, which are 0. 094% and 18. 39% of the analog control program, respectively. Therefore, the control solution of the digital PLL in frequency and the AGC in amplitude is feasible.

New digital drive phase control for improving bias stability of silicon MEMS gyroscope

In order to improve the bias stability of the micro-electro mechanical system（MEMS） gyroscope and reduce the impact on the bias from environmental temperature,a digital signal processing method is described for improving the accuracy of the drive phase in the gyroscope drive mode.Through the principle of bias signal generation,it can be concluded that the deviation of the drive phase is the main factor affecting the bias stability.To fulfill the purpose of precise drive phase control,a digital signal processing circuit based on the field-programmable gate array（FPGA） with the phase-lock closed-loop control method is described and a demodulation method for phase error suppression is given.Compared with the analog circuit,the bias drift is largely reduced in the new digital circuit and the bias stability is improved from 60 to 19 °/h.The new digital control method can greatly increase the drive phase accuracy,and thus improve the bias stability.

基于刚度轴偏角预估机制的MEMS多环谐振陀螺全闭环控制方法

针对微机电系统多环谐振陀螺正交闭环回路存在控制误差问题,提出一种基于刚度轴偏角预估机制的多环陀螺全闭环控制方法。该方法通过对微机电系统多环谐振陀螺刚度轴偏角预估,实现正交闭环回路参数自动优化调整。同时,提出了基于刚度轴偏角预估机制的全数字化闭环控制方法,实现微机电系统多环谐振陀螺的驱动、检测、正交、模态匹配环路的全闭环控制。该方法可提升正交闭环回路信噪比,增强陀螺正交漂移的抑制能力,降低陀螺零偏输出,改善陀螺的零偏不稳定性。实验结果表明,采用本文提出的基于刚度轴偏角预估机制的全闭环控制方法后,微机电系统多环谐振陀螺的零偏输出由0.201°/s降低为0.0213°/s,零偏不稳定性由39.42°/h降低为1.237°/h,分别降低了9.44倍和31.86倍,验证了该方法对提升微机电系统多环谐振陀螺仪性能的有效性。

Review of magnetorheological (MR) fluids and its applications in vibration control

Magnetorheological (MR) fluids are now well established as one of the leading materials for use in controllable structures and systems. Commercial application of MR fluids in various fields, particularly in the vibration control, has grown rapidly over the past few years. In this paper, properties of magnetorheological (MR) fluids ,its applications in suspensions of vehicles, suspension of trains, high buildings cable-stayed bridges have been discussed. The scope of MR fluids in future, problems and some suggestions are also presented. Finally, effectiveness of MR fluids in vibration control of marine diesel engine through experiment is briefly discussed by the author.

高精度MEMS硅谐振压力传感器闭环控制系统

硅谐振压力传感器因其数字频率信号输出和高精度的特点,被广泛应用于航空航天、工业控制等领域。硅谐振压力传感器的闭环控制系统决定硅谐振压力传感器的性能指标,系统的稳定性分析和参数优化则是谐振传感器的研究难点。基于系统状态方程从理论上推导了控制策略,提出系统稳定性判定依据。利用Simulink仿真搭建系统模型,并通过电路测试验证。结果表明,在满足稳定性判据的条件下,研制的硅谐振压力传感器基频为42 kHz,品质因数为30 000。在量程范围为3~130 kPa、温度为-55~85℃时,该谐振压力传感器的精度高达0.01%F.S.,实现了恒幅控制与实时频率跟踪。

Performance Analysis of a Profile Control Agent for Waste Drilling Fluid Treatment

A method for the treatment of hazardous waste drilling fluids,potentially leading to environmental pollution,is considered.The waste drilling fluid is treated with an inorganic flocculant,an organic flocculant,and a pH regulator.The profile control agent consists of partially hydrolyzed polyacrylamide,formaldehyde,hexamethylenetetramine,resorcinol,phenol,and the treated waste drilling fluid itself.For a waste drilling fluid concentration of 2500 mg/L,the gelling time of the profile control agent is 25 h,and the gelling strength is 32,000 mPa.s.Compared with the profile control agent prepared by recirculated water under the same conditions,the present profile control agent displays better stability,salt-resistance,and performance.

MEMS陀螺双通道数字接口系统设计

针对现有的MEMS陀螺接口系统只能对一个陀螺进行测控导致标定测控效率低下的问题,提出了一种新型的可同时对两个陀螺进行测控的MEMS陀螺双通道接口系统架构,并设计了一套与之对应的MEMS陀螺双通道测控电路,包括前端模拟电路、后端数字系统和人机交互终端。通过设计的人机交互系统对整个系统的全部功能进行了测试,其中扫频、锁相、稳幅、线性度和零偏稳定性等功能均能正常运行,在实际使用测试中相较于单通道接口系统测控效率提升到2倍以上。

Analysis of thermal management and anti-mechanical abuse of multi-functional battery modules based on magneto-sensitive shear thickening fluid

Electric vehicles(EVs)have garnered significant attention as a vital driver of economic growth and environmental sustainability.Nevertheless,ensuring the safety of high-energy batteries is now a top priority that cannot be overlooked during large-scale applications.This paper proposes an innovative active protection and cooling integrated battery module using smart materials,magneto-sensitive shear thickening fluid(MSTF),which is specifically designed to address safety threats posed by lithium-ion batteries(LIBs)exposed to harsh mechanical and environmental conditions.The theoretical framework introduces a novel approach for harnessing the smoothed-particle hydrodynamics(SPH)methodology that incorporates the intricate interplay of non-Newtonian fluid behavior,capturing the fluid-structure coupling inherent to the MSTF.This approach is further advanced by adopting an enhanced Herschel-Bulkley(H-B)model to encapsulate the intricate rheology of the MSTF under the influence of the magnetorheological effect(MRE)and shear thickening(ST)behavior.Numerical simulation results show that in the case of cooling,the MSTF is an effective cooling medium for rapidly reducing the temperature.In terms of mechanical abuse,the MSTF solidifies through actively applying the magnetic field during mechanical compression and impact within the battery module,resulting in 66%and 61.7%reductions in the maximum stress within the battery jellyroll,and 31.1%and 23%reductions in the reaction force,respectively.This mechanism effectively lowers the risk of short-circuit failure.The groundbreaking concepts unveiled in this paper for active protection battery modules are anticipated to be a valuable technological breakthrough in the areas of EV safety and lightweight/integrated design.

Research progress and development of deep and ultra-deep drilling fluid technology

The research progress of deep and ultra-deep drilling fluid technology systematically reviewed,the key problems existing are analyzed,and the future development direction is proposed.In view of the high temperature,high pressure and high stress,fracture development,wellbore instability,drilling fluid lost circulation and other problems faced in the process of deep and ultra-deep complex oil and gas drilling,scholars have developed deep and ultra-deep high-temperature and high-salt resistant water-based drilling fluid technology,high-temperature resistant oil-based/synthetic drilling fluid technology,drilling fluid technology for reservoir protection and drilling fluid lost circulation control technology.However,there are still some key problems such as insufficient resistance to high temperature,high pressure and high stress,wellbore instability and serious lost circulation.Therefore,the development direction of deep and ultra-deep drilling fluid technology in the future is proposed:(1)The technology of high-temperature and high-salt resistant water-based drilling fluid should focus on improving high temperature stability,improving rheological properties,strengthening filtration control and improving compatibility with formation.(2)The technology of oil-based/synthetic drilling fluid resistant to high temperature should further study in the aspects of easily degradable environmental protection additives with low toxicity such as high temperature stabilizer,rheological regulator and related supporting technologies.(3)The drilling fluid technology for reservoir protection should be devoted to the development of new high-performance additives and materials,and further improve the real-time monitoring technology by introducing advanced sensor networks and artificial intelligence algorithms.(4)The lost circulation control of drilling fluid should pay more attention to the integration and application of intelligent technology,the research and application of high-performance plugging materials,the exploration of diversified plugging techniques and methods,and the improvement of environmental protection and production safety awareness.

基于MEMS光栅光调制器阵列的动态图像显示控制方法

基于单片机控制的动态图像显示控制方法主要通过配置单片机参数实现对图像的显示控制,由于数据读写能力较弱,导致电压负荷较大。对此,提出基于微机电系统(Micro-Electro-Mechanical System,MEMS)光栅光调制器阵列的动态图像显示控制方法。将PC端输入的文字指令编码转换为光栅光调制器阵列的图像编码,采用异步读写的方式,对USB数据控制器的读写模式进行设计,构建出动态图像显示控制电路模块。在实验中,对提出的方法进行电压负荷的验证,经实验分析证明,利用提出的方法对动态图像进行显示控制,所需的工作电压和吸合电压值较低,对显示器的电压负荷较小。

Controlled Movements in Superlubric MEMS

Structural superlubricity(SSL)refers to a state where the friction and wear between two directly contacted solid surfaces are virtually zero.The realization of microscale SSL in 2012 rapidly explored SSL technologies which hold great potential in the development of reliable and energy⁃efficient micro devices.A key to a successful superlubric device is to control the movements of the superlubric slider.To solve this challenge,here two general principles are shown to guide and control the motion of the slider,i.e.,by minimization of interfacial energy and minimization of electrostatic energy.When the shapes of the slider and substrate are designed appropriately,the excess interfacial energy of the contact⁃pair provides restoring and constraining forces to the slider.Similarly,tunable driving and constraining forces are enabled by the electric fields induced by the electrodes buried in the substrate.These concepts are demonstrated on the design of a superlubric resonator whose natural frequency of the lateral translational mode is well⁃defined and unfavorable rotation is constrained.The above design principles should be applicable to superlubric devices in general and help the development of future applications of structural superlubricity.

Advanced flow measurement and active flow control of aircraft with MEMS

Advanced flow measurement and active flow control need the development of new type devices and systems.Micro-electro-mechanical systems(MEMS) technologies become the important and feasible approach for micro transducers fabrication.This paper introduces research works of MEMS/NEMS Lab in flow measurement sensors and active flow control actuators.Micro sensors include the flexible thermal sensor array,capacitive shear stress sensor and high sensitivity pressure sensor.Micro actuators are the balloon actuator and synthetic jet actuator respectively.Through wind tunnel test,these micro transducers achieve the goals of shear stress and pressure distribution measurement,boundary layer separation control,lift enhancement,etc.And unmanned aerial vehicle(UAV) flight test verifies the ability of maneuver control of micro actuator.In the future work,micro sensor and actuator can be combined into a closed-loop control system to construct aerodynamic smart skin system for aircraft.

MEMS高温压阻式压力传感器闭环控制方法

为提高MEMS高温压阻式压力传感器的整体性能,提出一种MEMS高温压阻式压力传感器闭环控制方法。明确MEMS高温压阻式压力传感器在工作过程中产生的变谐效应,分析了静电驱动和电容检测。根据分析结果设计出闭环控制策略,在闭环控制过程中采用二元差值算法补偿传感器的温度误差,提高控制精度。通过灵敏度校准和零点失调校准,实现了MEMS高温压阻式压力传感器的闭环控制。试验结果表明,所提方法的控制精度高、信号采集准确率高及控制性能好。

Several Applications of MEMS in Fluid Area

In order to discuss the several applications of MEMS in fluid area,study the components of MEMS.And introduce the principles,types and applications based on flow sensor and pressure sensor. In the last,discuss the problems when the sensors was applied in the fluid areas.

基于MEMS惯性传感器融合的水田激光平地机水平控制系统

激光平地技术是农业生产中一项重要的节本增效措施,为了使激光平地机在水田中作业时平地铲保持水平,设计了一种低成本的水田激光平地机水平控制系统,采用MEMS陀螺仪与加速度计通过信息融合测定平地铲实时倾角,通过脉冲宽度调节普通电磁阀实现平地铲水平控制。文章分析了控制系统的构成,传感器的工作原理与安装方法,阐述了两种传感器融合测量实时倾角的方法。采用了基于ARM7内核的微处理器设计了水平控制系统硬件,并给出了软件实现流程。采用AHRS(姿态航向参考系统)对系统性能进行了实验室测试与田间试验验证,测试结果表明,该水平控制系统能在动态条件下准确地测定平地铲实时倾角,可以较好地实现平地铲水平控制。

MEMS振动陀螺闭环自激驱动的理论分析及数值仿真

对采用AGC(automatic gain control)控制实现的陀螺闭环自激驱动系统进行了理论分析,利用平均技术和相平面法求解出了MEMS振动陀螺闭环自激驱动系统的起振条件以及幅度稳定条件的解析表达式,并进行了数值仿真验证。在该闭环驱动系统中,通过引入PI控制器消除了振动幅度控制的稳态误差。仿真结果很好地吻合了理论分析,理论分析结果可用于指导自激驱动系统的硬件实现。