Antonio Martínez-Álvarez

• Professor
• Professor (Full) at University of Alicante

This paper describes a bioinspired preprocessing and coding system devised for producing optimal multi-electrode stimulation at the cortical level, starting from image sequences and working at video rates. A hybrid platform with software and reconfigurable hardware delivers a continuously varying stream of pulses or spike patterns. The main objecti...

The protection of processor-based systems to mitigate the harmful effect of transient faults (soft errors) is gaining importance as technology shrinks. At the same time, for large segments of embedded markets, parameters like cost and performance continue to be as important as reliability. This paper presents a compiler-based methodology for facili...

A software technique based on approximate computing and redundancy is presented to mitigate radiation-induced soft errors in commercial off-the-shelf (COTS) microprocessors. Approximate computing relies on the capability of certain applications to accept imprecise results to improve efficiency by sacrificing its results in a controlled manner. Our...

A software technique is presented to protect commercial multi-core microprocessors against radiation-induced soft errors. Important time overheads associated with conventional software redundancy techniques limit the feasibility of advanced critical electronic systems. In our approach, redundant bare-metal threads are used, so that critical computa...

Statistical fault injection is widely used to estimate the reliability of mission-critical microprocessor-based systems when exposed to radiation and to evaluate the performance of fault mitigation strategies. However, further research is needed to gain a better understanding of the accuracy of the results and the feasibility of their application u...

This work presents the evaluation of a new dual-core lockstep hybrid approach aimed to improve the fault tolerance in microprocessors. Our approach takes advantage of modern multicore processor resources to combine software-based lockstep with a custom hardware observer. The first is used to duplicate data and instruction flows; meanwhile, the seco...

Dear Colleagues, in recent years, a growing trend has emerged addressed at improving data processing. From big data to artificial intelligence, strong requirements have arisen with regard to decreasing computational time while maintaining solutions’ quality. These require a high computational power, and therefore it is necessary to provide high-per...

A mathematical model is described to predict microprocessor fault tolerance under radiation. The model is empirically trained by combining data from simulated faultinjection campaigns, and radiation experiments, both with protons (at the CNA facilities, Seville, Spain) and with neutrons (at the LANSCE Weapons Neutron Research facility at Los Alamos...

This article presents a software protection technique against radiation-induced faults which is based on a multi-threaded strategy. Data triplication and instructions flow duplication or triplication techniques are used to improve system reliability and thus, ensure a correct system operation. To achieve this objective, a relaxed lockstep model to...

A significant challenge in neuroscience is understanding how visual information is encoded in the retina. Such knowledge is extremely important for the purpose of designing bioinspired sensors and artificial retinal systems that will, in so far as may be possible, be capable of mimicking vertebrate retinal behaviour. In this study, we report the tu...

This work presents a new Dual-Core LockStep approach to enhance fault tolerance in microprocessors. The proposed technique is based on the combination of software-based data checking and trace-based control-flow checking through an external hardware module. The hardware module is connected to the trace interface and is able to observe the execution...

A high-level C++ hardening library is designed for the protection of critical software against the harmful effects of radiation environments that can damage systems. A mathematical and empirical model to predict system behavior in the presence of radiation induced faults is also presented. This model generates a quick evaluation and adjustment of s...

A method is presented for automated improvement of embedded application reliability. The compilation process is guided using Genetic Algorithms and a Multi-Objective Optimization Approach (MOOGA). Even though modern compilers are not designed to generate reliable builds, they can be tuned to obtain compilations that improve their reliability, throu...

We investigate the automatic reliability improvement of embedded software when applying non-intrusive soft-computing techniques to tune the compilation process. Our fault-injection simulation results are correlated with different protons experiments. ARM-based SoCs and different programs have been used to assess our technique.

Este artículo propone una estrategia de mejora de la tolerancia frente a fallos producidos por radiación en sistemas empotrados complejos sin sistema operativo (standalone). Para alcanzar este objetivo, se han adaptado dos técnicas clásicas de tolerancia frente a fallos basadas en redundancia software en sistemas mono-núcleo, para explotar el paral...

Approximate Triple Modular Redundancy (ATMR), which is the implementation of TMR with approximate versions of the target circuit, has emerged in recent years as an alternative to partial hardware replication where designers can explore reduced area overhead combined with some compromise on fault masking. This work presents a novel approach for impl...

This paper presents a metric for the efficient application of selective hardening using software-based techniques against soft errors. It offers a method for selecting the resources to be protected obtaining maximum fault coverage with the minimum overhead. Common approaches are based on exhaustive exploration of the solution space or time-consumin...

Having a knowledge of muscle activity, one can draw conclusions related to human movement, health condition or even behaviour. Manual detection of a muscle activity based on the electromyographic (EMG) signals is a tedious and time-consuming task. Some applications require online indication what entails the need of automatic estimator. Popular and...

Grid-based perception techniques in the automotive sector based on fusing information from different sensors and their robust perceptions of the environment are proliferating in the industry. However, one of the main drawbacks of these techniques is the traditionally prohibitive, high computing performance that is required for embedded automotive s...

One of the basic questions in neuroscience is how visual information is encoded in the retina. To design artificial retinal systems it is essential to emulate the mammalian retinal behaviour as well as possible. Furthermore, this is a question of primary interest in the design of an artificial neuroprosthesis where it is necessary to mimic the reti...

Autonomous vehicle systems are currently the object of intense research within scientific and industrial communities; however, many problems remain to be solved. One of the most critical aspects addressed in both autonomous driving and robotics is environment perception, since it consists of the ability to understand the surroundings of the vehicle...

In this paper we present a method for autofocusing images of sputum smears taken from a microscope which combines the finding of the optimal focus distance with an algorithm for extending the depth of field (EDoF). Our multifocus fusion method produces an unique image where all the relevant objects of the analyzed scene are well focused, independen...

Reliability evaluation of Commercial off-the-shelf (COTS) processors against faults induced by radiation is a challenging problem. Some alternatives have been proposed to radiation test but they are very time consuming and lack of the observability needed. This work analyses the possibility to use an HDL model for estimating applications dependabil...

Many applications in computer vision require a high computational time for their processing. In general terms, those applications carry out several basic morphological real-time convolutions which are highly parallelizable. Using the above-mentioned convolutions along with a stack of images obtained with a digital microscope with different focusing...

This paper presents a fault injection system for performing fault injection campaigns on Commercial-off-the-shelf (COTS) microprocessors. The proposed system takes advantage of the debug facilities of modern microprocessors along with standard GNU Debugger (GDB) for executing and debugging benchmarks. The developed experiments on real boards, as we...

The retina is a very complex neural structure, which contains many different types of neurons interconnected with great precision, enabling sophisticated conditioning and coding of the visual information before it is passed via the optic nerve to higher visual centers. The encoding of visual information is one of the basic questions in visual and c...

This chapter aims to present different approaches and techniques available in literature regarding the fault mitigation on soft-core processors, with an especial emphasis on those ones involving hardware/software hybrid-based solutions.

The use of COTS FPGAs as deployment platform of microprocessor based systems represents an attractive alternative on aerospace applications, because their programmability, performance and cost-effectiveness. However, traditional hardening has a remarkable impact on resources and performance that limits their applicability. Selective hardening, that...

Human tremor can be defined as a somewhat rhythmic and quick movement of one or more body parts. From the mathematical point of view, human tremor can be defined as a weighted contribution of different sinusoidal signals which causes oscillations of some parts of the body. Two real cases have been tested using the algorithms developed in this inve...

Cortical prostheses are a subgroup of visual neuroprosthesis capable of eliciting visual percepts in profoundly blind people through direct stimulation of the occipital cortex. This approach is the only treatment available for blindness caused by glaucoma, optic atrophy or by diseases of the central visual pathways such as brain injuries or stroke....

The retina is responsible for transducing visual information into spikes trains which are then sent via the optical nerve to the visual cortex. This is the first step in the visual pathway responsible for the sense of vision. Our research group is working on the design of a cortical visual neuroprosthesis aimed to restore some functional vision to...

One of the many important functions the brain carries out is interpreting the external world. For this, one sense that most mammals rely on is vision. The first stage of the visual system is the image processing whose capture takes place in the retina. Here, photorecep-tors cells transform light into electrical impulses that are then guided by amac...

Human tremor can be defined as a somewhat rhythmic and quick movement of one or more body parts. In some people, it is a symptom of a neurological disorder. From the mathematical point of view, human tremor can be defined as a weighted contribution of different sinusoidal signals which causes oscillations of some parts of the body. This sinusoidal...

This paper analyses the nature of fault tolerance software-based techniques and the influence of their overheads to determine an efficient strategy for applying those techniques in a selective way. Several considerations that have to be taken into account are presented in this work. These include an analysis of fault coverage and overheads when sel...

Our eyes never remain still. Even when we stare at a fixed point, small involuntary movements take place in our eyes in an imperceptible manner. Researchers agree on the presence of three main contributions to eye movements when we fix the gaze: microsaccades, drifts and tremor. These small movements carry the image across the retina stimulating th...

There is an increasing concern to reduce the cost and overheads during the development of reliable systems. Selective protection of most critical parts of the systems represents a viable solution to obtain a high level of reliability at a fraction of the cost. In particular to design a selective fault mitigation strategy for processor-based systems...

The use of microprocessor-based systems is gaining importance in application domains where safety is a must. For this reason, there is a growing concern about the mitigation of SEU and SET effects. This paper presents a new hybrid technique aimed to protect both the data and the control-flow of embedded applications running on microprocessors. On o...

This paper presents a metric to estimate the register file criticality in processor-based systems. Due to project constrains, it is mandatory to identify and prioritize the most critical registers to protect when a selective fault mitigation approach is needed. The metric is based on the combination of three different criteria, which are computed d...

Commercial off-the-shelf microprocessors are the core of low-cost embedded systems due to their programmability and cost-effectiveness. Recent advances in electronic technologies have allowed remarkable improvements in their performance. However, they have also made microprocessors more susceptible to transient faults induced by radiation. These no...

The protection of processor-based systems to mitigate the harmful effects of transient faults (hardening) is gaining im-portance as technology shrinks. Hybrid hardware/software hardening approaches are promising alternatives in the de-sign of such fault tolerant systems. This paper presents a compiler-based infrastructure for facilitating the explo...

In this paper, a new approach to facilitate the development of heterogeneous embedded vision systems, by means of a software-friendly design flow is proposed. Our work is based on a framework called AMAZynq, especially focused on leverage the resources of Xilinx Zynq devices. Starting from an OpenCV code, the user defines explicitly the HW/SW parti...

Our eyes never remain still. Even when we stare at a point, small involuntary movements move our eyes in an imperceptible manner. Researchers agree on the presence of three main contributions to eye movements when we fix the gaze: microsaccades, drifts and tremor. These small movements carry the image across the retina stimulating the photoreceptor...

Neuroengineering is an emerging research field combining the latest findings from neuroscience with developments in a variety of engineering disciplines to create artificial devices, mainly for therapeutical purposes. In this chapter, an application of this field to the development of a visual neuroprosthesis for the blind is described. Electrical...

The retina is a very complex neural structure, which performs spatial, temporal, and chromatic processing on visual information and converts it into a compact ‘digital’ format composed of neural impulses. This paper presents a new compiler-based framework able to describe, simulate and validate custom retina models. The framework is compatible with...

We propose a new methodology for hardware/software co-design of embedded systems which is specifically aimed to mitigate SET effects. A hardening infrastructure is used to generate different versions of the design using several combinations of hardware and software hardening which are evaluated with respect to SET effects. The advantages of the pro...

This chapter will therefore present several technical solutions (at different design levels) which the authors have developed and applied to the development of the AraMiS built-in AOCS system. In particular, after analyzing the Requirements on small satellites AOCS, the following items will be discussed in detail: i) Attitude and Orbit Codeterminat...

Neuroengineering is an emerging research field combining the latest findings from neuroscience with developments in a variety of engineering disciplines to create artificial devices, mainly for therapeutical purposes. In this chapter, an application of this field to the development of a visual neuroprosthesis for the blind is described. Electrical...

There is an increasing interest in the aerospace industry to reduce the cost of the systems by means of using Commercial Off The Shelf (COTS) devices. The engineering of novel microsatellites and nanosatellites are clear examples of this new trend. However, the use of sub-micron technologies has led to greater sensitivity of these devices to radiat...

This paper remarks the importance of defining real conditions for the radiation effects evaluation on embedded systems using a fault injection system. The influence of fault latency on the experiment results is illustrated by means of a case study.

There is an increasing concern about the mitigation of radiation effects in embedded systems. This fact is demanding new flexible design methodologies and tools that allow dealing with design constraints and dependability requirements at the same time. This paper presents a novel proposal to design radiation-tolerant embedded systems combining hard...

Tool path generation is an important task that must be supported by the controller of a STEP-NC compliant CNC machine tool. However, these algorithms demand higher computation performance, which makes the implementation on many existing systems very slow or even impractical. This fact is one of the main barriers for the adoption of the STEP-NC stan...

The retina is a very complex neural structure, which contains many different types of neurons interconnected with great precision, enabling sophisticated conditioning and coding of the visual information before it is passed via the optic nerve to higher visual centers. Therefore the retina performs spatial, temporal, and chromatic processing on vis...

This paper presents a novel methodology for the HW/SW co-design of fault tolerant embedded systems that pursues the mitigation of radiation-induced upset events (which are a class of Single Event Effects - SEEs) on critical industrial applications. The proposal combines the flexibility and low cost of Software Implemented Hardware Fault Tolerance (...

This paper presents a novel low cost development environment for automatic hardening against Single Event Effects (SEE) of embedded systems through software redundancy. The environment is based on a generic architecture to handle multiple targets and is comprised of an automatic hardening compiler and an instruction set simulator. As a case study,...

Technological advances of Field Programmable Gate Array (FPGA) are making that this technology becomes the most preferred platform for the rapid prototyping of highly integrated digital systems. In addition, protection of processor-based systems to mitigate the harmful effects of radiation-induced upset events is gaining importance while technology...

In order to fulfill the new ISO 14649 (STEP-NC), Computer Numeric Control (CNC) machines need to support high computational demand algorithms. This fact is one of the main barriers for the adoption of the STEP-NC standard for CNC machines. Hardware acceleration is an incremental solution that can be cleanly added to these systems while keeping ever...

Tesis Univ. Granada. Departamento de Arquitectura y Tecnología de Computadores. Leída el 3 de mayo de 2006

The cooperation between neuroscience and biomedical engineering gave rise to a recent, but growing research field, known as neuroengineering. We follow its principles to have a system providing basic descriptions of the visual world to the brain's cortex. We describe a set of software and hardware tools to interface with neural tissue, in order to...

Tool path generation is one of the most complex problems in computer aided manufacturing. Although some efficient strategies have been developed, most of them are only useful for standard machining. The algorithm called virtual digitizing avoids this problem by its own definition but its computing cost is high and makes it difficult for being integ...

Tool path generation is one of the most complex problems in computer aided manufacturing. The algorithm called virtual digitizing avoids this problem by its own definition but its computing cost is high. Presented in the paper there is a virtual digitizing hardware/software architecture that takes advantage of field programmable gate arrays (FPGAs)...

Tool path generation is one of the most complex problems in computer aided manufacturing. Although some efficient strategies have been developed, most of them are only useful for standard machining. The algorithm called Virtual Digitizing avoids this problem by its own definition but its computing cost is high and make it difficult for being integr...

Neuro-engineering is providing biomedical engineers with technology to interface the nervous system, which is useful to create prosthetic devices to palliate sensorial or motor disabilities. Motivated by the success of cochlear implants for deaf patients, we are now facing the challenge of creating a prosthetic visual system for the blind. An artif...

This paper presents a synthesis tool for the automatic translation and optimization of bioinspired vision models into a FPL implementation. The software allows functional simulation and high level specification of the model, and produces a data-flow model using VHDL, which is synthesizable with different lower-level synthesis tools and for various...

In this paper, we present a tool devised for the automatic design and optimization of bioinspired visual processing models using reconfigurable hardware. We have focused on the simulation and optimization characteristics of our system. We also present a retina-like processing system based on a PCI-based FPGA board as an example. The whole system is...

This paper describes a tool devised for automatic design of bioinspired visual processing models using reconfigurable digital hardware. The whole system is indicated for the analysis of vision models, especially those with real–time requirements. We achieve a synthesizable FPGA/ASIC design starting from a high level description of a retina, which i...

Recent advances in arrays of microelectrodes open the door to both better understanding of the way the brain works and to the restoration of damaged perceptive and motor functions. In the case of sensorial inputs, direct multi-channel interfacing with the brain for neuro-stimulation requires a computational layer capable of handling the translation...

This work proposes a real-time bioinspired visual encoding system for multielectrodes stimulation of the visual cortex supported on Field Programmable Logic. This system includes the spatio-temporal preprocessing stage and the generation of time-varying spike patterns to stimulate an array of microelectrodes and can be applied to build a portable v...

This paper proposes a real-time bioinspired visual encoding system for multielectrodes' stimulation of the visual cortex supported on Field Programmable Logic. This system includes the spatio-temporal preprocessing stage and the generation of varying in time spike patterns to stimulate an array of microelectrodes and can be applied to build a porta...

Biotransformation of ent-3β,12α-dihydroxy-13-epi-manoyl oxide with Fusarium moniliforme gave the regioselective oxidation of the hydroxyl group at C-3 and the ent-7β-hydroxylation. The action of Gliocladium roseum in the 3,12-diketoderivative originated monohydroxylations at C-1 and C-7, both by the ent-β face, while Rhizopus nigricans produced hyd...

This paper describes a bio-inspired preprocessing and coding system devised for proper multielectrode stimulation at the primary visual cortex. After an introduction of the software/hardware (Sw/Hw) retina-like preprocessor as well as the system that produces a continuously varying stream of spike patterns, the paper presents a comparison of the sy...

Abstract This paper proposes a real - time bioinspired visual encoding system for multielectrodes' stimulation of the visual cortex supported on Field Programmable Logic This system includes the spatio - temporal preprocessing stage and the generation of varying in time spike patterns to stimulate an array of microelectrodes and can be applied to b...

The paper describes the implementation of a software/hardware (Sw/Hw) retina-like preprocessor designed for the study of bio-inspired visual processing schemes, and for experimentation in the development of a cortical visual neuro-prosthesis. The goal is to obtain, in the near future, an integrated artificial retina for a visual neuro-prosthesis pr...