Optical detection of multiple faults of a MEMS based linear comb resonator

Konduparthi, Lakshmi Deepasree

doi:10.33915/etd.1671

Cited by 4 publications

(5 citation statements)

References 11 publications

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“…Each of these cases was individually investigated using dSPACE a real-time control board. Detailed design specifications of LCRs, their parameter values and dimensions can be found in [26].…”

Section: B Experimental Resultsmentioning

confidence: 99%

“…Application of the optical method for measuring the displacement of the shuttle location is described in this section. Displacement feedback of the shuttle can be by the through wafer optical monitoring technique [26] to validate the position of the shuttle simultaneously. The through wafer optical displacement monitoring system contains an infrared waveguide of wavelength 1310 nm emitted from a laser diode.…”

Section: Optical Displacement Monitoring Techniquementioning

confidence: 99%

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Reliability Enhancement of MEMS Lateral Comb Resonators Under Fault Conditions

Izadian

Famouri

2008

IEEE Trans. Contr. Syst. Technol.

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The delicate structure of microelectromechanical systems (MEMS) limits their reliability in cases of fault occurrence. Control systems can enhance their reliability of operation by providing fault robust systems. This paper illustrates a method for the safe operation of lateral comb resonators (LCR) under faulty conditions. Different types of fault are fabricated at chip level and experimentally tested in order to demonstrate the effectiveness of the reliability enhancement of operation in LCRs. Mass change and folded spring structural defects influence the device's behavior and reduce its reliability of operation. Here, model reference adaptive controllers (MRACs) are effectively used to enhance the reliability of faulty devices. Reliable operation of a +5% additional mass considering environmental conditions and asymmetries on the device, demand almost 80% higher control effort whereas +20% in case of broken trusses or +46% in case of adhesion point fault on a beam of folded springs. The simulation and experiment results demonstrate successful application of MRAC for reliable operation of LCRs by providing a fault-robust system.

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Section: B Experimental Resultsmentioning

confidence: 99%

Section: Optical Displacement Monitoring Techniquementioning

confidence: 99%

Reliability Enhancement of MEMS Lateral Comb Resonators Under Fault Conditions

Izadian

Famouri

2008

IEEE Trans. Contr. Syst. Technol.

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“…Each of these cases was individually investigated using dSPACE ® , a real-time control board. Detailed design specifications of LCRs, their parameter values and dimensions can be found in (Konduparthi. 2005).…”

Section: Resultsmentioning

confidence: 99%

Automatic Control and Fault Diagnosis of MEMS Lateral Comb Resonators

Izadian¹

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Automatic Control and Fault Diagnosis of MEMS Lateral Comb Resonators Afshin Izadian Recent advancements in microfabrication of Micro Electro Mechanical Systems have made MEMS an important part of many applications such as safety and sensor/control devices. Miniature structure of MEMS makes them very sensitive to the environmental and operating conditions. In addition, fault in the device might change the parameters and result in unwanted behavioral variations. Therefore, imperfect device structure, fault and operating point dependencies suggest for active control of MEMS. This research is focused on two main areas of control and fault diagnosis of MEMS devices. In the control part, the application of adaptive controllers is introduced for trajectory control of the device under health and fault conditions. Fault in different forms in the structure of the device are modeled and foundry manufactured for experimental verifications. Pull-in voltage effect in the MEMS Lateral Comb Resonators are investigated and controlled by variable structure controllers. Reliability of operation is enhanced by active control of the device under fault conditions. The second part of this research is focused on the fault diagnosis of the MEMS devices. Fault is introduced and investigated for better understanding of the system behavioral changes. Modeling of the device in different operating conditions suggests for the multiple-model adaptive estimation (MMAE) fault diagnosis technique. Application of Kalman filters in MMAE is investigated and the performance of the fault diagnosis is compared with other techniques such as self-tuning and auto self-tuning techniques. According to the varying parameters of the system, online parameter identification systems are required to monitor the parameter variations and model the system accurately. Self-tuning banks are applied and combined with MMAE to provide accurate fault diagnosis systems. Different parameter identification techniques result in different system performances. In this regard, this research investigates the application of Recursive Least Square with Forgetting Factor. Different techniques for tuning of forgetting factor value are introduced and their results are compared for better performance. The organization of this dissertation is as follows: Chapter I introduces the structure of the MEMS Lateral Comb Resonator; Chapter II introduces the application of control techniques and displacement feedback approach. Chapter III investigates the control approach and experimental results. In chapter IV, a new controller is introduced and designed for the MEMS trajectory controls. Chapter V is about the fault and different techniques of fault diagnosis in MEMS LCRs. Chapter 6 is the future work suggested through the current results and observations. Each chapter contains a section to summarize the concluding remarks. iii To my Parents and my wife Pardis iv Acknowledgement: I would like to thank all previous members of WVU MEMS research group, whose work has made this research possible. E...

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“…Those types of lenses reduce the number of lenses needed to test multiple MEMS devices and allow for the use of multiple lenses to probe a single device. The dual spot lenses would also allow for a reference beam and measurement beam setup for a single device as has been used on the laser Doppler vibrometer in previous work [14]. The tests and analysis used on the on-axis lenses can be applied to the dual spot, off-axis lenses for testing their ability to detect motion of MEMS devices.…”

Section: Discussion Of Lens Results and Connection To Diffraction Theorymentioning

confidence: 99%

“…Previous research [14] in the group has provided better understanding, control, and fault detection knowledge of MEMS devices. This work was made possible partly through the use of laser Doppler vibrometry which displays the on going need for such a system.…”

Section: Prior Mems Workmentioning

confidence: 99%

Characterization of diffractive optical lenses for use in MEMS integrated optical monitoring

Hollandsworth¹

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Mechanical Machines (MEMS) are finding use in an increasing number of applications. Many of these applications, especially safety critical ones, require continuous knowledge of the operational status of the MEMS device over its lifetime. In-situ monitoring of the operational status of these devices is better suited to optical methods which provide a non-invasive way of continuously determining device position as a function of time. This data is central to determining the MEMS state and operational condition. Whether the optical source is internal to the MEMS package or external to the package and introduced via optical fiber, lenses will be required within the package to focus the MEMS optical probe beam to and from the test device. The need for hybrid co-integration with the MEMS die within its package results in physical dimension and focal length constraints on the lenses used and points toward the applicability of diffractive optical lenses to realize the goal of MEMS insitu integrated optical monitoring. The spot diameter must be of a width comparable to any lateral displacement that must be measured so that acceptable resolution of the motion can be observed. Diffractive lenses are capable of meeting all of these requirements. Previous work designed and fabricated Fresnel binary phase diffractive lenses in borofloat glass substrates as a means to achieve the required lens function for either a visible (632 nm wavelength) or near IR (1310 nm) probe beam. This work undertakes the full optical characterization of these previously fabricated lenses, compares their performance (spot size, focal length, efficiency) to that expected from theory, and determines if they meet the original lens design criteria, These results enable an initial assessment of these lenses for use in MEMS in-situ lifetime optical monitoring.

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Optical detection of multiple faults of a MEMS based linear comb resonator

Cited by 4 publications

References 11 publications

Reliability Enhancement of MEMS Lateral Comb Resonators Under Fault Conditions

Reliability Enhancement of MEMS Lateral Comb Resonators Under Fault Conditions

Automatic Control and Fault Diagnosis of MEMS Lateral Comb Resonators

Characterization of diffractive optical lenses for use in MEMS integrated optical monitoring

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