H∞ Loop shaping control for PLL-based mechanical resonance tracking in NEMS resonant mass sensors

International audienceAbstract--A simple dynamic detection of the resonance frequency shift in NEMS resonant mass sensors is described. This is done without the use of an external frequency sweep signal nor a frequency counter limiting the dynamic variation detection. Neither an amplitude control nor a phase switcher is required for maintaining the resonant oscillations. The sensor is driven directly by the VCO's output for which the control signal is calculated by a robust H∞ controller using loopshaping method. Only the sensor and the VCO's signals signs are detected and compared so that the controller regulates the phase difference between them, maintaining it at π / 2 which occurs on resonance frequency. The measurement issue is transformed to a novel control problem that rejects the disturbance described by the resonance frequency shift, attenuates the phase noise and guarantees good stability margins

Microbeam dynamic shaping by closed-loop electrostatic actuation using modal control

International audienceA closed-loop control approach for the dynamic shaping of a microbeam by electrostatic actuation is described. Starting from a desired displacements reference vector of N small segments of the beam (representing the approximation of the continuous case), n controllers (n is the number of considered modes) output the stresses that must be distributed throughout the beam, on the N actuators. Because this reference may vary with time, the controllers are designed so that they accomplish good response dynamics, as well as performance and robustness specifications. The innovation in this method is that we control the dynamic coefficients associated to the modes of the microbeam and not directly the physical displacements in each small segment, which reduces the number of correctors from N to the number of n modes to control

A robust control method for electrostatic microbeam dynamic shaping with capacitive detection

International audienceA robust closed-loop control and observation methodology for an electrostatic dynamic shaping of a microbeam using N small separate electrodes is described. After decomposing the displacements vector on the n eigenmodes using the modal analysis, n controllers are designed to control the dynamic coefficients of each mode and thus to deliver the stresses that must be distributed throughout the beam. In previous works, we considered direct access to non noisy displacement measurements. In this paper, we investigate the capacitive measurement of the local displacements done by each small electrode, which gives a noisy readout. Robust control methodology applied on extended standard model permits to design n observers associated to n controllers and guarantees precise shape tracking, free from noise and robust against parameters incertitud

Application des techniques de contrôle aux réseaux de micro et nanostructures

One of the most important benefits provided by M/NEMS is their ability to be fabricated in a massive way combining them into arrays. However, many problems limit the use of such systems such as control complexity, elements dispersion and couplings, non-linearities and noise sources, etc. Hence, it is crucial to take these features into consideration since the design stage, eliminating their effects or making advantage of them to make new architectures that achieve high performances. A contribution to flexible micro-structures control is developed using a large array of distributed nano-transducers. The continuous structure is then replaced by a NEMS array whose model is detailed for the first time in function of existing dispersions. Coupled arrays architectures are suggested in order to reduce the dispersions effects, enhancing by that the selectivity of the derived filters. Based on the distributed transductions scheme, a novel tuning strategy is elaborated by using modal control. The different arrays (coupled or not) can be used in sensing applications, where the measurement system is modelled depending on the used technique and on the chosen structure before improving the performances by appropriate control. A new configuration based on transduction nonlinearities is designed for variation compensation and measurement of a sensor resonance frequency allowing system complexity reduction.Un des plus importants profits qu'on peut tirer des M/NEMS est la capacité de les fabriquer en grande masse permettant leur assemblage sous forme de réseau. Toutefois, de nombreux problèmes s'opposent à l'utilisation de ces systèmes tels que la complexité de leur contrôle, la non-uniformité et les couplages entre leurs éléments, les sources de bruits et de non-linéarités, etc.. Il est alors nécessaire de prendre en compte ces différents aspects dès la phase de conception, les corriger ou les exploiter, pour aboutir à des nouvelles architectures qui répondent aux exigences de hautes performances. En se servant d'un large réseau de nano-transducteurs, une contribution au contrôle dynamique robuste d'une micro-surface « intelligente » est développée. La structure continue est ensuite remplacée par un réseau de NEMS dont le modèle est détaillé pour la première fois en tenant compte des dispersions entre les éléments. Des architectures de réseaux couplés sont proposées pour réduire les effets des dispersions, améliorant ainsi la sélectivité des filtres résultants. Basée sur le schéma de transductions distribuées, une nouvelle stratégie d'ajustement du filtre est élaborée par contrôle modal. Ces différents réseaux (couplés ou non) peuvent être utilisés pour des applications capteurs où le système de mesure est modélisé en fonction de la technique utilisée et de la structure adoptée avant d'améliorer les performances par un contrôle approprié. Une nouvelle configuration exploitant les non-linéarités de transduction est proposée pour compenser et mesurer la variation de la fréquence de résonance permettant de réduire la complexité du système global

Hinf loop-shaping control of a PLL-based oscillation loop for dynamic resonance tracking in NEMS mass sensors arrays

International audienc

Application des techniques de contrôle sur les réseaux de micro et nanostructures

Un des plus importants profits qu'on peut tirer des M/NEMS est la capacité de les fabriquer en grande masse permettant leur assemblage sous forme de réseau. Toutefois, de nombreux problèmes s'opposent à l'utilisation de ces systèmes tels que la complexité de leur contrôle, la non-uniformité et les couplages entre leurs éléments, les sources de bruits et de non-linéarités, etc.. Il est alors nécessaire de prendre en compte ces différents aspects dès la phase de conception, les corriger ou les exploiter, pour aboutir à des nouvelles architectures qui répondent aux exigences de hautes performances. En se servant d'un large réseau de nano-transducteurs, une contribution au contrôle dynamique robuste d'une micro-surface intelligente est développée. La structure continue est ensuite remplacée par un réseau de NEMS dont le modèle est détaillé pour la première fois en tenant compte des dispersions entre les éléments. Des architectures de réseaux couplés sont proposées pour réduire les effets des dispersions, améliorant ainsi la sélectivité des filtres résultants. Basée sur le schéma de transductions distribuées, une nouvelle stratégie d'ajustement du filtre est élaborée par contrôle modal. Ces différents réseaux (couplés ou non) peuvent être utilisés pour des applications capteurs où le système de mesure est modélisé en fonction de la technique utilisée et de la structure adoptée avant d'améliorer les performances par un contrôle approprié. Une nouvelle configuration exploitant les non-linéarités de transduction est proposée pour compenser et mesurer la variation de la fréquence de résonance permettant de réduire la complexité du système global.One of the most important benefits provided by M/NEMS is their ability to be fabricated in a massive way combining them into arrays. However, many problems limit the use of such systems such as control complexity, elements dispersion and couplings, non-linearities and noise sources, etc. Hence, it is crucial to take these features into consideration since the design stage, eliminating their effects or making advantage of them to make new architectures that achieve high performances. A contribution to flexible micro-structures control is developed using a large array of distributed nano-transducers. The continuous structure is then replaced by a NEMS array whose model is detailed for the first time in function of existing dispersions. Coupled arrays architectures are suggested in order to reduce the dispersions effects, enhancing by that the selectivity of the derived filters. Based on the distributed transductions scheme, a novel tuning strategy is elaborated by using modal control. The different arrays (coupled or not) can be used in sensing applications, where the measurement system is modelled depending on the used technique and on the chosen structure before improving the performances by appropriate control. A new configuration based on transduction nonlinearities is designed for variation compensation and measurement of a sensor resonance frequency allowing system complexity reduction.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Modal control of mechanically coupled NEMS arrays for tunable RF filters

International audienceA novel tuning strategy of nanoelectromechanical systems (NEMS)-based filters is proposed based on the modal control of mechanically coupled NEMS arrays. This is done by adjusting separately addressed distributed actuation and detection configurations proportionally to desired modal vectors. This control scheme enhances the global output signal, raising the power handling of the filter on all channels. Although the modal control of 1-D arrays exhibits narrow-band responses with adjustable resonance frequency, its application to 2-D arrays produces filters with both adjustable bandwidth and central frequency. One possible realization scheme is suggested by using electrostatically driven coupled NEMS arrays whose transduction gains are adjusted by changing the electrodes' bias voltages. Dispersion effects on both 1-D array and 2-D array frequency response are analytically expressed using eigenvalues perturbation theory. Based on these results, we show how to reduce their impact by appropriately choosing the coupling stiffness and the number of resonators