Quadrature error and offset error suppression circuitry for silicon micro-gyroscope

The reasons for inducing quadrature error and offset error are analyzed and the expressions of quadrature error and offset error are induced. The open-loop system analysis indicates that, in order to avoid the appearance of harmonic peaks, the frequency difference δf between drive mode and sense mode must be less than 1/（2Qy）. In order to eliminate the effects of the quadrature error and the offset error, as well as the inherent non- linearity in the capacitance-type sensors, a closed-loop feedback control circuit with quadrature correction is designed. The experimental results indicate that the quadrature error and offset error are corrected. By comparing with open-loop detection, the closed-loop feedback control circuit with quadrature correction decreases the non-linearity of the scale factor from 16. 02% to 0. 35 %, widens the maximum rate capability from ± 270 （°）/s to ± 370 （°）/s and increases the stability of zero bias from 155. 2 （°）/h to 60. 6 （°）/h.

Drive and Control of Electromagnetic Drive Module on Reciprocally Rotating Disc Used for Micro-Gyroscope

An innovative 3-phase AC (Alternative Current) drive circuit for the seismic disc in micro-gyroscopes is designed and verified by computer simulations and experiments. The in-plane dynamic model of the seismic disc with mass eccentricity and air gap against the centre bearing and the mathematic expression of two sinusoidal magnetic fields are developed respectively. In order to prevent the seismic disc from collision with the centre bearing and the EM (Electromagnetic) poles, an anti-collision controller is established by employing two Look-up tables which define the intensity of the applied current to the EM poles. Self-sensing technique is included to measure the real-time offset of the disc by two orthogonal pairs of EM poles, without any additional sensors. The drive circuit under SPWM (Sinusoidal Pulse Width Modulation) operation and the anti-collision strategy are verified by intensive computer simulations via commercial software, OrCAD 9, and experiments.

Analysis and Control of Novel Deflection-Type PM Multi-DOF Actuator

This paper mainly presents a PM multi-DOF actuator for robot in-wheels drive applications and its control method. The torque model is established based on the finite-element model of the single pair poles in 3D finite element method software. Due to the special structure of the actuator,the Euler angles are adopted for deriving the kinematics and dynamic model. To reduce the effects of uncertainties of modeling error,nonlinear friction and external disturbances in the system,an approximation of neural network adaptive control method is applied to the actuator. The computation and simulation results show that the proposed analysis and control method can effectively derive the characteristics and improve the motion performance,which provides the primary theoretical guide for the configuration design,optimization and control research of multi-DOF deflection type actuators.

A novel closed-loop vacuum silicon microgyroscope

A novel closed-loop control strategy of a silicon microgyroscope （SMG） is proposed. The SMG is sealed in metal can package in drive and sense modes and works under the air pressure of 10 Pa. Its quality factor reaches greater than l0 000. Self-oscillating and closed-loop methods based on electrostatic force feedback are adopted in both measure and control circuits. Both single side driving and sensing methods are used to simplify the drive circuit. These dual channel decomposition and reconstruction closed loops are applied in sense modes. The testing results demonstrate that useful signals and guadrature signals do not interact with each other because of the decoupling of their phases. Under the condition of a scale factor of 9. 6 mV/（（°） .s）, in a full measurement range of±300 （°）/s, the zero bias stability reaches 28 （°）/h with a nonlinear coefficient of 400 × 10^-6 and a simulated bandwidth of more than 100 Hz. The overall performance is improved by two orders of magnitude in comparison to that at atmospheric pressure.

多自由度球形感应电机的驱动控制策略

为实现城市微型电动汽车全方位转向功能,对新型多自由度(multi-DOF)球形感应电机(SIM)驱动控制策略进行仿真。从SIM设计原理和结构特性出发,提出了一种多自由度驱动控制策略。分析SIM转矩输出情况;以球形转子偏转角度为依据,设定4个工作扇区;通过判断球形转子偏转角度所在扇区位置,来调整各定子工作状态;采用直接转矩控制策略,使各定子在球形转子上产生的转矩输出沿目标方向。结果表明:该SIM控制策略可实现2个自由度的旋转驱动控制,且转子无偏转角度限制,同时具有良好的动态特性和跟随性能。从而,验证了驱动控制策略的可行性和合理性。

Flexible Bio-tensegrity Manipulator with Multi-degree of Freedom and Variable Structure

Conventional manipulators with rigid structures and sti ness actuators have poor flexibility,limited obstacle avoidance capability,and constrained workspace.Some developed flexible or soft manipulators in recent years have the characteristics of infinite degrees of freedom,high flexibility,environmental adaptability,and extended manipulation capability.However,these existing manipulators still cannot achieve the shrinking motion and independent control of specified segments like the animals,which hinders their applications.In this paper,a flexible bio-tensegrity manipulator,inspired by the longitudinal and transversal muscles of octopus tentacles,was proposed to mimic the shrinking behavior and achieve the variable motion patterns of each segment.Such proposed manipulator uses the elastic spring as the backbone,which is driven by four cables and has one variable structure mechanism in each segment to achieve the independent control of each segment.The variable structure mechanism innovatively contains seven lock-release states to independently control the bending and shrinking motion of each segment.After the kinematic modeling and analysis,one prototype of such bionic flexible manipulator was built and the open-loop control method was proposed.Some proof-of-concept experiments,including the shrinking motion,bending motion,and variable structure motion,were carried out by controlling the length of four cables and changing the lock-release states of the variable structure mechanism,which validate the feasibility and validity of our proposed prototype.Meanwhile,the experimental results show the flexible manipulator can accomplish the bending and shrinking motion with the relative error less than 6.8%through the simple independent control of each segment using the variable structure mechanism.This proposed manipulator has the features of controllable degree-of-freedom in each segment,which extend their environmental adaptability,and manipulation capability.

Modeling and Analysis of a Micromotor with an Electrostatically Levitated Rotor

The modeling and evaluation of a prototype rotary micromotor where the annular rotor is supported electrostatically in five degrees of freedom is presented in order to study the behavior of this levitated micromotor and further optimize the device geometry. The analytical torque model is obtained based on the principle of a planar variable-capacitance electrostatic motor while the viscous damping caused by air film between the stator and rotor is derived using laminar Couette flow model. Simulation results of the closed-loop drive motor, based on the developed dynamic model after eliminating mechanical friction torque via electrostatic suspension, are presented. The effects of the high-voltage drive, required for rotation of the rotor, on overload capacity and suspension stiffness of the electrostatic bearing system are also analytically evaluated in an effort to determine allowable drive voltage and attainable rotor speed in operation. The analytical results show that maximum speed of the micromotor is limited mainly by viscous drag torque and stiffness of the bearing system. Therefore, it is expected to operate the device in vacuum so as to increase the rotor speed significantly, especially for those electrostatically levitated micromotors to be used as an angular rate micro-gyroscope.

Complete decoupling rebalance loop design of a micromachined electrostatically suspended gyroscope

A micromachined electrostatically suspended gyroscope(MESG)based on UV-LIGA microfabrication process was introduced.By close-loop control,the suspended rotor is kept in null position and through the torque rebalance loop,in which the output control voltages reflects the input angular velocity,a dual-axis input angular velocity can be measured simultaneously.First,the system model of MESG was established by dynamic analysis based on the torque analysis.Then,the rebalance loop under ideal condition is designed using modern control technique.The performance of the designed decoupling rebalance loop was compared with that of conventional proportional integral differential(PID)rebalance loop combined with the compensation loop.In order to realize the decoupling of the output voltages,a compensated decoupling matrix and its difference equation were presented and realized by a digital decoupling method employing digital signal processor(DSP).It was confirmed that the controller could realize the complete decoupling and improve the performance of the gyroscope,which includes merits of fast response speed,low overshoot and good dynamic performance,as the simulation results shown.At last,the circuit and digital realization scheme were given.

静电驱动下指数型变截面梁式陀螺仪的非线性特性与分析

本文设计一类新型的指数型变截面梁式微陀螺,变截面指数梁的宽度与长度的关系为指数函数变化的形式,且指数梁的截面变化因子小于等于零,梁的厚度随梁长仍保持不变.考虑了曲率非线性和惯性非线性对系统的影响,利用扩展哈密顿原理、单模近似法和拉格朗日微分方程,建立了指数型变截面梁式非线性陀螺仪的振动控制方程、边界条件和非线性离散化模型,且考虑了陀螺仪驱动和检测两个方向上直流电压和交流电压对系统响应的影响,采用ADM法求解陀螺仪系统在不同截面变化因子下的静态响应,利用多尺度法对系统的非线性离散化模型进行摄动求解,分析各个参数对陀螺仪动态响应的影响规律.结果表明,随着截面变化因子的增大,指数梁陀螺仪的吸合电压和一阶固有频率逐渐增加,并呈现近似线性的变化规律.通过调节指数梁截面变化因子,可以控制科氏力响应峰值频率和检测峰值频率的差值.利用指数梁陀螺仪系统的硬化非线性特征,当交流电压施加在指数梁厚度方向时,选择合适的指数截面变化因子、阻尼比和交流电压,可以使指数梁式陀螺仪系统获得更好的带宽性能及线性可测范围;当交流电压施加在指数梁宽度方向,选取合适的截面变化因子,不仅可以获得较高的系统灵敏度性能,同时增加陀螺仪对外部输入角速度的线性可测范围.

MEMS and MOEMS Gyroscopes: A Review

Micro-gyroscopes using micro-electro-mechanical system(MEMS)and micro-optoelectro-mechanical system(MOEMS)are the new-generation and recently well-developed gyroscopes produced by the combinations of the traditional gyroscope technology and MEMS/MOEMS technologies.According to the working principle and used materials,the newly-reported micro-gyroscopes in recent years include the silicon-based micromechanical vibratory gyroscope,hemispherical resonant gyroscope,piezoelectric vibratory gyroscope,suspended rotor gyroscope,microfluidic gyroscope,optical gyroscope,and atomic gyroscope.According to different sensitive structures,the silicon-based micromechanical vibratory gyroscope can also be divided into double frame type,tuning fork type,vibrating ring type,and nested ring type.For those micro-gyroscopes,in recent years,many emerging techniques are proposed and developed to enhance different aspects of performances,such as the sensitivity,angle random walk(ARW),bias instability(BI),and bandwidth.Therefore,this paper will firstly review the main performances and applications of those newly-developed MEMS/MOEMS gyroscopes,then comprehensively summarize and analyze the latest research progress of the micro-gyroscopes mentioned above,and finally discuss the future development trends of MEMS/MOEMS gyroscopes.

All-Fabric Bi-directional Actuators for Multi-joint Assistance of Upper Limb

According to clinical studies,upper limb robotic suits are vital to reduce therapist fatigue and accelerate patient rehabilitation.Soft pneumatic actuators have drawn increasing attention for the development of wearable robots due to their low weight,flexibility,and high power-to-weight ratio.However,most of current actuators were designed for the flexion assistance of a specific joint,and that for joint extension requires further investigation.Furthermore,designing an actuator for diverse working scenarios remains a challenge.In this paper,we propose an all-fabric bi-directional actuator to assist the flexion and extension of the elbow,wrist,and fingers.A mathematical model is presented that predicts the deformation and guides the design of the proposed bi-directional actuator.To further validate the applicability and adaptability of the proposed actuator for different joints,we developed a 3-DOF soft robotic suit.Preliminary results show that the robotic suit can assist the motion of the elbow,wrist,and finger of the subject.

Study on the Behavior of Solar Array Deployment with Root Hinge Drive Assembly

In this paper, a method of using a root hinge drive assembly （RHDA） to control the solar array deployment is provided and a multi-DOF mechanism dynamic model of the system is established. In this way, the root hinge torque can be calculated iteratively. Then taking the predicted torque as a reference, a RHDA is designed for a large multiple-stage packaging and deployable solar array system. The control effect of the drive assembly is validated by ground tests. The test results indicate that the solar arrays can be deployed smoothly, and the deployment velocities are restricted by the drive assembly as expected. During the tests, the RHDA output speed and output torque are obtained. In order to examine the impact force when the yoke is lock-up with a hard stop, dynamics simulations are performed according to the actual behavior. The simulation result indicates that the designed RHDA reduces the impact force significantly and improves the lock-up reliability effectively.