This paper establishes a link between closed-loop controls for heterogeneous systems and sliding mode controls. We demonstrate that sliding mode analysis matches with experimental results from dielectric charge controllers. This approach provides a new way to analyze the behaviour of different heterogeneous systems.
This paper introduces Diffusive Representation as a novel approach to characterize the dynamics of charge trapped in dielectric layers of microelectromechanical systems (MEMS) through a fitting process. Diffusive Representation provides a computationally efficient method to achieve an arbitrary order state-space model of the charging dynamics. This approach is particularly well
suited to analyze the dynamics of the dielectric charge under non trivial controls, as in the case of sliding mode controllers. The diffusive symbol of the experimental structure has been obtained from open-loop measurements, in which Pseudo Random Binary Sequences (PRBS) are applied to the device. The obtained model exhibits good agreement with experimental data and also allows to model the behaviour of the charge dynamics under excitation with arbitrary binary signals.
Dominguez, M.; Atienza, M.T.; Kowalski, L.; Novio, S.; Gorreta, S.; Jimenez, V.; Silvestre, S. IEEE transactions on industrial electronics Vol. 64, num. 1, p. 664-673 DOI: 10.1109/TIE.2016.2605621 Data de publicació: 2016-09-01 Article en revista
The objective of this paper is to analyze the dynamics of heat flow in thermal structures working under constant temperature operation. This analysis is made using the tools of sliding mode controllers. The theory is developed considering that the thermal system can be described using diffusive representation. The experimental corroboration has been made with a prototype of a wind sensor for Mars atmosphere being controlled by a thermal sigma-delta modulator. This sensor structure allows to analyze experimentally the time-varying case since changes in wind conditions imply changes in the corresponding thermal models. The diffusive symbols of the experimental structures have been obtained from openloop measurements in which pseudo-random binary sequences of heat are injected in the sensor. With the proposed approach it is possible to predict heat flux transient waveforms in systems described by any arbitrary number of poles. This allows for the first time the analysis of lumped and distributed systems without any limitation on the number of poles describing it.
Kowalski, L.; Atienza, M.T.; Gorreta, S.; Jimenez, V.; Dominguez, M.; Silvestre, S.; Castañer, L. IEEE sensors journal Vol. 16, num. 7, p. 1887-1897 DOI: 10.1109/JSEN.2015.2509168 Data de publicació: 2016-04-01 Article en revista
A novel wind speed and direction sensor designed
for the atmosphere of Mars is described. It is based on a spherical
shell divided into four triangular sectors according to the central
projection of tetrahedron onto the surface of the unit sphere.
Each sector is individually controlled to be heated above the
ambient temperature independently of the wind velocity and incidence
angle. A convection heat rate model of four hot spherical
triangles under forced wind has been built with finite element
method thermal-fluidic simulations. The angular sensitivity of the
tetrahedral sphere structure has been theoretically determined
and compared with the tessellation of the sphere by four biangles.
A 9-mm-diameter prototype has been assembled using 3-D printing
of the spherical shell housing in the interior commercial
platinum resistors connected to an extension of a custom
design printed board. Measurements in Martianlike atmosphere
demonstrate sensor responsiveness to the flow in the velocity
range 1–13 m/s at 10-mBar CO2 pressure. Numerical modelization
of the sensor behavior allows to devise an inverse algorithm
to retrieve the wind direction data from the raw measurements
of the power delivered to each spherical sector. The functionality
of the inverse algorithm is also demonstrated.
Gorreta, S.; Barajas, E.; Kowalski, L.; Atienza, M.T.; Dominguez, M.; Jimenez, V. Electronics Letters Vol. 51, num. 19, p. 1499-1500 DOI: 10.1049/el.2015.1947 Data de publicació: 2015-09-17 Article en revista
A new circuit is described which applies a configurable voltage across an RTD while the current flowing through it is measured with a current mirror. The circuit also allows working with voltages above the IC supply voltage to cope with the high power RTD dissipation normally required in thermal anemometers. The circuit is periodically calibrated to cancel the errors and amplifier offset and therefore improves measurement accuracy. Experimental measurements of the circuit fabricated using 0.35 mu m AMS technology show the functionality and improved power efficiency.