Ariel Lutenberg

Optical encoder based on a nondiffractive beam III

In two preceding works (Appl. Opt.47, 2201-2206, 2008; Appl. Opt.48, 414-424, 2009) we introduced the design of an optical encoder based on a nondiffractive beam and studied the dependence of its performance on its parameters (e.g., grating pitch, photodetector size). In those works we proposed different optimization criteria and concluded that the proposed design provides an output sinusoidal signal with high contrast and very low harmonic distortion, while having remarkable tolerance to variations in its parameters and to mechanical perturbations. In this work we (1) study how to improve the system performance by means of selecting appropriate photodetector geometry, (2) study the system performance for different nondiffractive beam geometries, and (3) quantify the output signal tolerance to vertical and lateral misalignment between the centers of the nondiffractive beam and the photodetector. As a consequence, we obtain new sets of optimal parameters that significantly improve the system performance and enhance its tolerance to mechanical perturbations and fabrication errors.

Linear displacement measurement with a grating and speckle pattern illumination

We present a study of the variations of a speckle pattern passing through a grating that can be displaced. This study is described theoretically by a simple model based on the scalar diffraction theory in the Fresnel zone. The intensity correlation of the modified speckle as a function of the grating displacement is obtained and compared with experimental results. The possibilities of metrological applications in optical encoders are suggested.

On the trade-off of power consumption and time synchronization quality in Wireless Sensor Networks

In this work we find a lower bound on the energy required for synchronizing a Wireless Sensor Network (WSN) based on clock estimation techniques. The energy required for synchronizing a WSN is specified by both the transmit power and the required number of messages in order to achieve a desired estimation error level. This paper brings two main contributions: 1. A general relationship between the energy spent in the transmission and the clock offset estimation error by means of the number of transmitted messages, for both large-scale and small-scale wireless channel fading. 2. An optimal lower bound on the required energy and the number of messages by minimizing their product.

Evaluating the Effects of Combined Total Ionizing Dose Radiation and Electromagnetic Interference

Although measurement methods for Electromagnetic (EM) immunity and Total Ionizing Dose (TID) radiation are highly standardized, little effort has been made though, to evaluate the behavior of embedded systems under the combined effects. Considering realistic environment conditions only the measurement of these effects can guarantee reliable embedded systems for critical applications. A configurable platform to evaluate the effects of TID radiation and EM Interference (EMI) on embedded systems is presented. Experiments illustrate the consequences regarding delay and fault occurrence probability as well as current consumption and minimum power supply.

Developing an intermediate embedded-systems course with an emphasis on collaboration

Embedded systems are computing devices designed to perform specific tasks as part of larger systems such as digital cameras, measuring instruments, cars, etc. Technological advances have added complexity to embedded-systems development, which needs to be reflected in academic curricula. This paper presents the design and delivery of an intermediate embedded-systems course that follows up on a typical introduction to microcontrollers and, while doing so, it offers an example of engineering-course development that makes use of collaborative learning, outbound ties and learning modes of a community of practice. The paper explains planning, learning objectives, activities and other aspects of the course, including hardware and software tools used as well as lessons learned. A section is dedicated to student projects and current results.

Design of a Portable System for Continuous Recording of Arterial Parameters during 24h

The simultaneous measurement of pressure and diameter in a central artery during 24 hours could bring new information about the variability of the arterial mechanical properties. In order to perform these measurements in an animal, it is essential to count with a device that could acquire the signals from the sensors with a proper preconditioning circuit and then transfer them wirelessly to be stored and processed remotely. In this paper we present the prototype of a new portable and autonomous device, capable of being hosted on the animals back. Preliminary results obtained from a pilot experience in a sheep using the prototype are detailed and limitations are discussed.

Configurable platform for IC combined tests of total-ionizing dose radiation and electromagnetic immunity

The roadmap for standardization of electromagnetic (EM) immunity measurement methods has reached a high degree of success with the IEC 62.132 proposal. The same understanding can be taken from the MIL-STD-883H for total ionizing dose (TID) radiation. However, no effort has been performed to measure the behavior of electronics operating under the combined effects of both, EM noise and TID radiation. For secure embedded systems and systems-on-chip (SoC) devoted to critical applications, these combined-effect measurements are mandatory. In this paper, we present a configurable platform devoted for combined tests of EM immunity and TID radiation measurements of prototype embedded systems. The platform attends the IEC 62.132–2 (for radiated EM noise), IEC 61.0004–17 and IEC 61.0004–29 (for conducted EM disturbance) and 1019.8 method for TID Test Procedure of MIL-STD-883H.

Work in progress — Development of an integrated circuits course that includes the full experience of designing an ASIC in a CMOS process

This work presents the development and first experiences in a course of design of digital and analog integrated circuits using a CMOS process in a country and university which do not have strong traditions on microelectronics. During the first two months of the course, lectures are given on specific topics, leaving the last months to work on a design project proposed by the students themselves, which is fabricated. The course ends when students characterize the functionality of their circuits.

A novel consensus algorithm proposal: Measurement estimation by silent agreement (MESA)

Energy consumption is one of the fundamental problems in wireless sensor networks (WSN). In this paper the energy optimization problem is addressed in a clustered wireless network by proposing a novel consensus algorithm that guarantees an uniformly distributed energy consumption reduction by means of combining local and global rules applied to the censoring technique. The algorithm is illustrated by means of an example and it is formally stated in mathematical terms. Lastly, its outstanding performance is shown by means of numerical simulations.

Design of an extensible, portable and POSIX compliant protocol

The aim of this article is to introduce a protocol for embedded systems that delivers data between two nodes independently of the characteristics of the link. The development is platform independent and virtually portable to any communication standard. To demonstrate the performance of our protocol it was implemented in an ARM Cortex M3 LPC1769 microcontroller of NXP using first an UART serial protocol and then TCP/IP sockets. The protocol was implemented using object oriented techniques, POSIX standards and several abstraction layers.