Drive-Mode Control for Vibrational MEMS Gyroscopes

This paper presents a novel design methodology and hardware implementation for the drive-mode control of vibrational micro-electro-mechanical systems gyroscopes. Assuming that the sense mode (axis) of the gyroscope is operating under open loop, the drive-mode controller compensates an undesirable mechanical spring-coupling term between the two vibrating modes, attenuates the effect of mechanical-thermal noise, and most importantly, forces the output of the drive mode to oscillate along a desired trajectory. The stability and robustness of the control system are successfully justified through frequency-domain analysis. The tracking error between the real output and the reference signal for the drive mode is proved to be converging with the increase of the bandwidth of the controller. The controller is first simulated and then implemented using field-programmable analog array circuits on a vibrational piezoelectric beam gyroscope. The simulation and experimental results verified the effectiveness of the controller

Robust Controller Design for an Electrostatic Micromechanical Actuator

In this paper, a robust feedback controller is developed on an electrostatic micromechanical actuator to extend the travel range of it beyond pull-in limit. The actuator system is linearized at multiple operating points, and the controller is constructed based on the linearized model. Two kinds of controller designs are developed for set-point tracking of the actuator despite the presences of sensor noise and external disturbance. One of them is a regular fourth order Active Disturbance Rejection Controller (ADRC) and is able to achieve 97% of the maximum travel range. And the other one is a novel multi-loop controller with a second order ADRC in an inner loop and a PI controller in an outer loop. The multi-loop controller can achieve 99% of the maximum travel range. Transfer function representations of both controller designs are developed. The controllers are successfully applied and simulated on a parallel-plate electrostatic actuator model. The simulation results and frequency domain analyses verified the effectiveness of the controllers in extending the travel range of the actuator, in disturbance rejection, and in noise attenuation

Robust Controller Design for an Electrostatic Micromechanical Actuator

In this paper, a robust feedback controller is developed on an electrostatic micromechanical actuator to extend the travel range of it beyond pull-in limit. The actuator system is linearized at multiple operating points, and the controller is constructed based on the linearized model. Two kinds of controller designs are developed for set-point tracking of the actuator despite the presences of sensor noise and external disturbance. One of them is a regular fourth order Active Disturbance Rejection Controller (ADRC) and is able to achieve 97% of the maximum travel range. And the other one is a novel multi-loop controller with a second order ADRC in an inner loop and a PI controller in an outer loop. The multi-loop controller can achieve 99% of the maximum travel range. Transfer function representations of both controller designs are developed. The controllers are successfully applied and simulated on a parallel-plate electrostatic actuator model. The simulation results and frequency domain analyses verified the effectiveness of the controllers in extending the travel range of the actuator, in disturbance rejection, and in noise attenuation

Adaptive Control of an Active Magnetic Bearing with External Disturbance

Adaptive back stepping control (ABC) is originally applied to a linearized model of an active magnetic bearing (AMB) system. Our control goal is to regulate the deviation of the magnetic bearing from its equilibrium position in the presence of an external disturbance and system uncertainties. Two types of ABC methods are developed on the AMB system. One is based on full state feedback, for which displacement, velocity, and current states are assumed available. The other one is adaptive observer based back stepping controller (AOBC) where only displacement output is measurable. An observer is designed for AOBC to estimate velocity and current states of AMB. Lyapunov approach proves the stabilities of both regular ABC and AOBC. Simulation results demonstrate the effectiveness and robustness of two controllers

On Control System Design for the Conventional Mode of Operation of Vibrational Gyroscopes

This paper presents a novel control circuitry design for both vibrating axes (drive and sense) of vibrational gyroscopes, and a new sensing method for time-varying rotation rates. The control design is motivated to address the challenges posed by manufacturing imperfection and environment vibrations that are particularly pronounced in microelectromechanical systems (MEMS) gyroscopes. The method of choice is active disturbance rejection control that, unlike most existing control design methods, does not depend on an accurate model of the plant. The task of control design is simplified when the internal dynamics, such as mechanical cross coupling between the drive and sense axes, and external vibrating forces are estimated and cancelled in real time. In both simulation and hardware tests on a vibrational piezoelectric beam gyroscope, the proposed controller proves to be robust against structural uncertainties; it also facilitates accurate sensing of time-varying rotation rates. The results demonstrate a simple, economic, control solution for compensating the manufacturing imperfections and improving sensing performance of the MEMS gyroscopes

A Robust Decentralized Load Frequency Controller for Interconnected Power Systems

A novel design of a robust decentralized load frequency control (LFC) algorithm is proposed for an inter-connected three-area power system, for the purpose of regulating area control error (ACE) in the presence of system uncertainties and external disturbances. The design is based on the concept of active disturbance rejection control (ADRC). Estimating and mitigating the total effect of various uncertainties in real time, ADRC is particularly effective against a wide range of parameter variations, model uncertainties, and large disturbances. Furthermore, with only two tuning parameters, the controller provides a simple and easy-to-use solution to complex engineering problems in practice. Here, an ADRC-based LFC solution is developed for systems with turbines of various types, such as non-reheat, reheat, and hydraulic. The simulation results verified the effectiveness of the ADRC, in comparison with an existing PI-type controller tuned via genetic algorithm linear matrix inequalities (GALMIs). The comparison results show the superiority of the proposed solution. Moreover, the stability and robustness of the closed-loop system is studied using frequency-domain analysis

On Control System Design for the Conventional Mode of Operation of Vibrational Gyroscopes

This paper presents a novel control circuitry design for both vibrating axes (drive and sense) of vibrational gyroscopes, and a new sensing method for time-varying rotation rates. The control design is motivated to address the challenges posed by manufacturing imperfection and environment vibrations that are particularly pronounced in microelectromechanical systems (MEMS) gyroscopes. The method of choice is active disturbance rejection control that, unlike most existing control design methods, does not depend on an accurate model of the plant. The task of control design is simplified when the internal dynamics, such as mechanical cross coupling between the drive and sense axes, and external vibrating forces are estimated and cancelled in real time. In both simulation and hardware tests on a vibrational piezoelectric beam gyroscope, the proposed controller proves to be robust against structural uncertainties; it also facilitates accurate sensing of time-varying rotation rates. The results demonstrate a simple, economic, control solution for compensating the manufacturing imperfections and improving sensing performance of the MEMS gyroscopes

Transcriptome and comparative gene expression analysis of Phyllostachys edulis in response to high light

The values of gene expression in Calvin cycle and photorespiratory metabolism. (XLSX 12 kb

Building environment assessment methods and social studies of rural villages in Yunnan and urban development in Chongqing City, Southwest China

Recent urbanization processes and corresponding government policies in China have highlighted the need for much greater understanding of sustainable development and the requirements for sustainability in settings that are very different in rural and urban regions. This paper examines practice and knowledge linked to typical vernacular houses constructed since 1950 in Yunnan Province and regional buildings in Chongqing City in Southwest China. Both areas have played crucial roles in contributing to regional architectural design since the beginning of the 20th Century because of the diversity arising from numerous ethnic groups and various climate types and topography features in the region. The study explores how academic and end-user knowledge accumulated and developed, and how this has revealed social, cultural and political influences on how designers and consumers were motivated towards sustainable design over the same time period. It is argued that locally shared knowledge bases should be considered important for informing governmental policies, planning strategy and consumers’ preferences, as well as influencing actions and social acceptance in relation to sustainable development. Furthermore, sustainable design should not be regarded as a contemporary new idea, but one that has its roots in the historical changes in built environment design and practice