Design, Modelling and Control of IRST Capacitive MEMS Microphone

Condenser MEMS microphones are becoming a promising technology to substitute the current standard microphones, and modelling such systems has become very important for designing a condenser microphone fulfilling the given constrains. In this dissertation a deep analysis of capacitive MEMS microphone has been presented coming up with a complete model which is able to fit the experimental data of the microphone sensitivity. Furthermore, a simple noise model, able to fit the experimental data, has been developed considering the well-know Brownian noise and the more subtle 1/f component, usually neglected. With such models, it is possible to have a reliable estimation of the microphone SNR. Many characterizations have been performed on the produced samples and different problems of the manufacturing process have been highlighted, gaining a deeper understanding on the structure of the microphone and on the production process. Finally, to reply to the more and more demanding constraints, two applications of control law have been applied: a force feedback and a controller to tune the resonant frequency of the microphone. This last application shows how a controller can make the system more flexible and reduce the problem of some defects on the production. The force feedback is a technique already used in MEMS systems, such as gyroscopes and accelerometers, where it has shown to be able to improve the performance of the systems. In the presented configuration, a force feedback has been implemented in a digital readout interface, realizing the so-called electromechanical sigma delta converter. Its stability has been evaluated and the improvements have been verified experimentally: due to the extra filtering action of the embedded MEMS system inside the converter loop, the A-weighted in-band noise has been reduced from -63dBA to -73dBA

A null-space-based control for cable driven manipulators

Cable driven systems have been applied in several manipulators and due to their high backdrivability and apparent low inertia have been successfully used in telemanipulation systems. However, in order to achieve high performances, a control to keep the cables taut is needed. In this paper, a position control in the null and range space is used to avoid cables from slacking and to achieve the desired performances. Indeed, a cable driven manipulator is a redundant system and its null space represents the internal forces, that is the tensions of the cables. To guarantee robustness against model parametric uncertainties and external disturbances, a position based disturbance observer has been designed. Proof of stability of the proposed control and bounds of the estimation error have been given. Simulation and experimental results show that the proposed control achieve the desired performances keeping the cables taut

Improving the performance of Higher Order Disturbance Observers: A position approach

The disturbance observer (DOB) is a tool for the robust motion control and it is used to compensate the disturbances. In the design of the DOB\u27 it is assumed that\u27 the system disturbance is observed and compensated by the DOB in the range of its bandwidth. However\u27 the whole bandwidth cannot be compensated by the DOB due to the dynamical characteristics of the disturbance observer\u27s low pass filter (LPF). Higher Order Disturbance Observer (HODOB) is one of the fundamental tools to increase the performance of the DOB\u27 even though it has some disadvantages. However\u27 the performance analysis of HODOB has not been clearly reported yet. In this paper\u27 analysis and design methods of the HODOB are presented by using a more general disturbance model. This general model gives more freedoms to design HODOB. Also the superiors of the position measurement based HODOB design are shown. Simulation and experimental results are given to show the validity of the proposed methods

Development and characterization of touch sensing devices for robotic applications

This paper presents the development of touch sensing chips for robotic applications and the experimental results from touch sensing elements on the chip. The high resolution tactile sensing chips have overall dimension of 1.5 cm à 1.5 cm and consist of 25 touch sensing elements. The touch sensing elements on the chip are the POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistor) devices, obtained by depositing piezoelectric polymer directly on to the gate area of MOS transistor. Each sensing element has an effective sensing area of 0.5 mm à 0.5 mm. The tactile sensing chips are suitable for fingertips of a robot where large numbers of sensors are needed in a small space (typically 1 cm à 1.5 cm). The tactile sensing elements on the chip have been experimentally evaluated in time and frequency domain. Typically, protective rubber films of materials like PDMS (Polydimethylsiloxane) are used to improve robustness of the sensors, albeit, at the cost of reduced sensitivity. Such effects on the response of POSFET touch sensing elements are studied with PDMS films having different thicknesses

Development and characterization of touch sensing devices for robotic applications

This paper presents the development of touch sensing chips for robotic applications and the experimental results from touch sensing elements on the chip. The high resolution tactile sensing chips have overall dimension of 1.5 cm \uc3\u97 1.5 cm and consist of 25 touch sensing elements. The touch sensing elements on the chip are the POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistor) devices, obtained by depositing piezoelectric polymer directly on to the gate area of MOS transistor. Each sensing element has an effective sensing area of 0.5 mm \uc3\u97 0.5 mm. The tactile sensing chips are suitable for fingertips of a robot where large numbers of sensors are needed in a small space (typically 1 cm \uc3\u97 1.5 cm). The tactile sensing elements on the chip have been experimentally evaluated in time and frequency domain. Typically, protective rubber films of materials like PDMS (Polydimethylsiloxane) are used to improve robustness of the sensors, albeit, at the cost of reduced sensitivity. Such effects on the response of POSFET touch sensing elements are studied with PDMS films having different thicknesses

Piston-type condenser microphone with structured polysilicon

A miniature silicon condenser microphone with a reinforced piston type diaphragm has been developed. The microphone, with a highly sensitive diaphragm (1mm2 in area) and a highly rigid back plate has been fabricated in a single wafer process. The equivalent electrical circuit method and the finite element method (FEM) have been used to evaluate the acoustic and mechanical performance of the microsensor. A procedure to achieve a structure with optimal mechanical sensitivity has been proposed and diaphragms with different geometries have been designed and simulated with this method. Sensitivities in the range of 5 - 10 mVPa-1 can be achieved under bias voltages of 1.5 - 7 V for devices with frequency bandwidths between 10 and 50 kHz

Obesity and high waist circumference are associated with low circulating pentraxin-3 in acute coronary syndrome

BACKGROUND: Long pentraxin 3 (PTX3) is a component of the pentraxin superfamily and a potential marker of vascular damage and inflammation, associated with negative outcome in patients with acute coronary syndromes (ACS). Obesity is a risk factor for cardiovascular disease and PTX3 production is reported in abdominal adipose tissue. Low PTX3 is however reported in the obese population, and obesity per se may be associated with less negative ACS outcome. METHODS: We investigated the potential impact of obesity and high waist circumference (reflecting abdominal fat accumulation) on plasma PTX3 concentration in ACS patients (n\u2009=\u200972, 20 obese) compared to age-, sex- and BMI-matched non-ACS individuals. RESULTS: Both obese and non-obese ACS patients had higher PTX3 than matched non-ACS counterparts, but PTX3 was lower in obese than non-obese individuals in both groups (all P\u2009<\u20090.05). PTX3 was also lower in ACS subjects with high than in those with normal waist circumference (WC). Plasma PTX3 was accordingly associated negatively with BMI and WC, independently of age and plasma creatinine. No associations were observed between PTX3 and plasma insulin, glucose or the short pentraxin and validated inflammation marker C-reactive protein, that was higher in ACS than in non-ACS individuals independently of BMI or WC. CONCLUSIONS: Obesity is associated with low circulating PTX3 in ACS. This association is also observed in the presence of abdominal fat accumulation as reflected by elevated waist circumference. Low PTX3 is a novel potential modulator of tissue damage and outcome in obese ACS patients

Molecular diagnosis of hypobetalipoproteinemia: An ENID review

Primary hypobetalipoproteinemia (HBL) includes a group of genetic disorders: abetalipoproteinemia (ABL) and chylomicron retention disease (CRD), with a recessive transmission, and familial hypobetalipoproteinemia (FHBL) with a co-dominant transmission. ABL and CRD are rare disorders due to mutations in the MTP and SARA2 genes, respectively. Heterozygous FHBL is much more frequent. FHBL subjects often have fatty liver and, less frequently, intestinal fat malabsorption. FHBL may be linked or not to the APOB gene. Most mutations in APOB gene cause the formation of truncated forms of apoB which may or may be not secreted into the plasma. Truncated apoBs with a size below that of apoB-30 are not detectable in plasma; they are more frequent in patients with the most severe phenotype. Only a single amino acid substitution (R463W) has been reported as the cause of FHBL. Approximately 50% of FHBL subjects are carriers of pathogenic mutations in APOB gene; therefore, a large proportion of FHBL subjects have no apoB gene mutations or are carriers of rare amino acid substitutions in apoB with unknown effect. In some kindred FHBL is linked to a locus on chromosome 3 (3p21) but the candidate gene is unknown. Recently a FHBL plasma lipid phenotype was observed in carriers of mutations of the PCSK9 gene causing loss of function of the encoded protein, a proprotein convertase which regulates LDL-receptor number in the liver. Inactivation of this enzyme is associated with an increased LDL uptake and hypobetalipoproteinemia. HBL carriers of PCSK9 mutations do not develop fatty liver disease