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Full-Text Articles in Engineering
Sensing And Control Of Mems Accelerometers Using Kalman Filter, Kai Zhang
Sensing And Control Of Mems Accelerometers Using Kalman Filter, Kai Zhang
ETD Archive
Surface micromachined low-capacitance MEMS capacitive accelerometers which integrated CMOS readout circuit generally have a noise above 0.02g. Force-to-rebalance feedback control that is commonly used in MEMS accelerometers can improve the performances of accelerometers such as increasing their stability, bandwidth and dynamic range. However, the controller also increases the noise floor. There are two major sources of the noise in MEMS accelerometer. They are electronic noise from the CMOS readout circuit and thermal-mechanical Brownian noise caused by damping. Kalman filter is an effective solution to the problem of reducing the effects of the noises through estimating and canceling the states contaminated …
Development Of A Focused Broadband Ultrasonic Transducer For High Resolution Fundamental And Harmonic Intravascular Imaging, Chaitanya K. Chandrana
Development Of A Focused Broadband Ultrasonic Transducer For High Resolution Fundamental And Harmonic Intravascular Imaging, Chaitanya K. Chandrana
ETD Archive
Intravascular ultrasound (IVUS) is increasingly employed for detection and evaluation of coronary artery diseases. Tissue Harmonic Imaging provides different tissue information that could additionally be used to improve diagnostic accuracy. However, current IVUS systems, with their unfocussed transducers, may not be capable of operating in harmonic imaging mode. Thus, there is a need to develop suitable transducers and appropriate techniques to allow imaging in multi modes for complementary diagnostic information. Focused PVDF TrFE transducers were developed using MEMS (Micro-Electro-Mechanical-Systems) compatible protocols. The transducers were characterized using pulse-echo techniques and exhibited broad bandwidth (110 at -6dB) with axial resolutions of Such …
Modeling And Feedback Control Of A Mems Electrostatic Actuator, Jason Edwards
Modeling And Feedback Control Of A Mems Electrostatic Actuator, Jason Edwards
ETD Archive
This thesis describes the mathematical modeling and closed-loop voltage control of a MEMS electrostatic actuator. The control goal is to extend the travel range of the actuator beyond the open-loop pull-in limit of one third of the initial gap. Three controller designs are presented to reach the control goal. The first controller design utilizes a regular fourth order Active Disturbance Rejection Controller (ADRC) and is able to achieve 97 of the maximum travel range. The second design also uses a fourth order ADRC, while additional modeling information is included in an Extended State Observer (ESO), which is part of the …
The Development Of An In Vivo Spinal Fusion Monitor Using Microelectromechanical (Mems) Technology To Create Implantable Microsensors, Lisa Anne Ferrara
The Development Of An In Vivo Spinal Fusion Monitor Using Microelectromechanical (Mems) Technology To Create Implantable Microsensors, Lisa Anne Ferrara
ETD Archive
Surgical fusion of the spine is a conventional approach, and often last alternative, to the correction of a degenerative painful spinal segment. The procedure involves the surgical removal of the intervertebral disc at the problematic site, and the placement of a bone graft that is commonly harvested from the patients iliac crest and placed within the discectomized space. The surrounding bone is expected to incorporate and remodel into the bone graft to eventually provide an immobilized site. Spinal instrumentation often accompanies the bone graft to provide further immobility to the targeted site, thus augmenting the fusion process. However, the status …
Mems (Micro-Electro-Mechanical-Systems) Based Microfluidic Platforms For Magnetic Cell Separation, Pulak Nath
Mems (Micro-Electro-Mechanical-Systems) Based Microfluidic Platforms For Magnetic Cell Separation, Pulak Nath
ETD Archive
Microfluidic platforms for magnetic cell separation were developed and investigated for isolation of magnetic particles and magnetically tagged cells from a fluidic sample. Two types of magnetic separation platforms were considered: an Isodynamic Open Gradient Magnetic Sorter (OGMS) and a multistage bio-ferrograph. Miniaturized magnets were designed using magnetostatic simulation software, microfluidic channels were fabricated using microfabrication technology and magnetic separation was investigated using video microscopy and digital image processing. The isodynamic OGMS consisted of an external magnetic circuit and a microfabricated channel (biochip) with embedded magnetic elements. The biochip is placed inside the magnetic field of the external circuit to …
Hardware Implementation Of Active Disturbance Rejection Control For Vibrating Beam Gyroscope, David Avanesian
Hardware Implementation Of Active Disturbance Rejection Control For Vibrating Beam Gyroscope, David Avanesian
ETD Archive
Obtaining the approximation of rotation rate form a Z-Axis MEMS gyroscope is a challenging problem. Currently, most commercially available MEMS gyroscopes are operating in an open-loop for purposes of simplicity and cost reduction. However, MEMS gyroscopes are still fairly expensive and are not robust during operation. The purpose of this research was to develop a high-performance and low-cost MEMS gyroscope using analog Active Disturbance Rejection Control (ADRC) system. By designing and implementing analog ADRC both above requirements were satisfied. Analog ADRC provides the fastest response time possible (because the circuit is analog), eliminates both internal and external disturbances, and increases …