Embedded Electronic Systems Research Articles

Dynamics of precision-guided projectile launch: fluid–structure interaction

Precision-guided projectiles (PGPs) experience severe shock loads during launch emanating from the propellant gases and the surrounding air. The complex flow environment that exists within the confined space of the barrel and at muzzle exit is significantly influenced by the speed of the projectile, the compressibility of the air, and the rapid state transition of the projectile from the confined volume of the barrel to the surrounding free space. In this effort, we extend our earlier vacuum work (Yin et al. in Int J Mech Mater Des 10:439–450. https://doi.org/10.1007/s10999-014-9255-0 , 2014) by performing comprehensive and a more realistic multiphysics simulations of the dynamics of the entire launch process of a projectile accounting for the intense combustion pressures of the propellant, the large accelerations experienced during the launch, and the induced shock waves. Our numerical model successfully captured the development and progression as well as the interaction of the projectile with the induced shock waves. Specifically, the model identifies the intense pressures generated by the propellant that result in supersonic flow conditions within the confined space of the barrel. This supersonic flow within the barrel leads to a wave front that travels ahead of the projectile creating a normal shock wave in the barrel. Once the normal shock crosses the muzzle exit, it diffracts into three types of shock waves: precursor, bow, and base. These shock loads pose a significant threat to the embedded electronic systems (EES) necessary for the operation, guidance and control of these PGPs. Our model further reveals that the projectile will experience a reduction in velocity as a result of induced frictional drag and interaction with the induced shock waves. This study will assist in the design and development of appropriate encapsulation techniques necessary for the protection of EES.

Dynamics of Precision Guided Projectile Launch: Solid–Solid Interaction

Precision guided projectiles (PGPs) experience severe shock loads during launch emanating from the propellant gases inside the barrel and the surrounding air. The complex flow environment that exists within the confined space of the barrel and at muzzle exit is greatly influenced by the supersonic speed of the projectile, the compressibility of the air, and the rapid state transition of the projectile from the confined volume of the barrel to the surrounding free-space. In our earlier efforts (X. W. Yin, P. Verberne and S. A. Meguid, Multiphysics modelling of the coupled behaviour of precision-guided projectiles subjected to intense shock loads, Int. J. Mech. Mater. Des. 10 (2014) 439–450; P. Verberne and S. A. Meguid, The coupled behaviour of precision-guided projectiles subject to propellant induced shock loads using multiphysics analysis, in 8th Int. Conf. Mech. Mater. Des. (2019); P. Verberne and S. A. Meguid, Dynamics of precision guided projectile launch: Fluid-structure interaction, Acta Mech. (2020)) examined the fluid–solid interaction problem. In this paper, we expand our earlier effort by examining the underlying mechanisms associated with the solid–solid interaction between the projectile and the barrel walls that severely govern the survivability of the embedded electronic systems (EES). This was achieved by conducting comprehensive finite element (FE) simulations of the dynamics of the entire launch process of a projectile accounting for the intense combustion pressures of the propellant, the large accelerations experienced during the launch and the induced shock waves. Our FE simulations successfully capture the interaction of the projectile with the barrel. Our work reveals that frictional forces due to contact inside the barrel significantly affect the projectile’s acceleration response at muzzle exit. Immediately following muzzle exit, the rapid reduction of the frictional forces inside the barrel results in a rapid increase of the projectile acceleration followed by a rapid reduction due to the free expansion of the propellant gases and air drag, leading to large acceleration fluctuations.

A portable laser-based sensor for detecting H2S in domestic natural gas

Abstract Hydrogen sulfide (H2S) is a highly toxic gaseous component of natural gas that poses a significant hazard during the use of natural gas for domestic purposes; therefore, a high-sensitivity, on-line detection method is extremely important to ensure its safety for domestic use. In this work, a portable sensor was developed based on near-infrared tunable diode laser absorption spectroscopy (TDLAS). A special Herriott multipass cell (MPC) combined with a home-made embedded electronics system allowed for the fabrication of a compact sensor with a size of 50 × 20 × 10 cm3. A rugged movable cell was used for detecting contaminated gas samples. An embedded electronic system with a diameter of 8 cm was implemented to control the laser, acquire and process electronic signal. To reduce external interference, the calibration-free TDLAS (wavelength modulation frequency-2f/direct sine signal) was employed to suppress common field measurement noise. Based on the results of Allan deviation analysis, the limit of system detection could reach 0.14 ppm using the H2S absorption line at 6336.61 cm−1. It is suitable for on-line measurement because of its rapid response time. Its feasibility is validated for monitoring H2S in a domestic natural gas of pipeline. This work demonstrates a system for real-time and field measurement of H2S, which can be used to address the security risks associated with using natural gas.

Embedded solutions for a class of highly unstable, underactuated and self-balancing robotic systems

This paper presents a didactic framework in embedded electronics systems that is used to elicit awareness into students and engineers on the design issues arising in the realization of a class of underactuated robots and aerial vehicles that needs be robustly controlled due to their intrinsic unstability. The applications prototyped on the embedded platform presented here are conceived, by design, to be compliant with tiny collaborative robotics applications in order to adhere to the needs of the complex cyber-physical systems problem. The proposed platform is self-contained with on-board sensing and computation. Its engineering uses only off-the-shelf and mass production components. The system is based on a general purpose embedded board equipped with a 32-bit microcontroller which is able to manage all the basic tasks of this robotic platform: sensing, actuation, control and communication. The framework is described, and initial experimental results are introduced. Three applications are presented in this work as a validation of the methodology: a ballbot robot, a legged robot and a quadrotor aerial vehicle. The chosen case studies are robotics applications that are specialized in performing maneuvers when operating in tight spaces as in the human living environments.

Two-functional µBIST for Testing and Self-Diagnosis of Analog Circuits in Electronic Embedded Systems

The paper concerns the testing of analog circuits and blocks in mixed-signal Electronic Embedded Systems (EESs), using the Built-in Self-Test (BIST) technique. An integrated, two-functional, embedded microtester (µBIST) based on reuse of signal blocks already present in an EES, such as microprocessors, memories, ADCs, DACs, is presented. The novelty of the µBIST solution is its extended functionality. It can perform 2 testing functions: functional testing and fault diagnosis on the level of localization of a faulty element. For functional testing the Complementary Signals (CSs), and for fault diagnosis the Simulation Before Test (SBT) vocabulary techniques have been used. In the fault vocabulary the graphical signatures in the form of identification curves in multidimensional spaces have been applied.

Introductory notes for the Acta IMEKO Special Issue on "Technical Diagnostics : New Perspectives in Measurements, Tools and Techniques for Industrial Applications"

The concept of Quality has undergone important transformations over time. In a first assumption, sometimes passed in many industrial contexts, the term “product quality” was essentially associated with “compliance”. Nowadays, the term “conformity to specifications” is widely used but this has to be considered only as an aspect in the measurement of the quality level. In fact, referring to the ISO Standard 9001 Quality management systems, the term Quality corresponds with the degree to which a set of characteristics of an object fulfils requirements. Concerning characteristics, such Standard proposes a classification in physical (e.g. mechanical, electrical, etc.), temporal (e.g. reliability, availability, etc.), and so on. It is interesting to observe that also the concept of product changed over time. Now, it is usual to assume the product as the result of a manufacturing process in which a series of activities transforms raw materials, technologies and resources into the output – that is the product. So, it is mandatory to implement different activities concerning monitoring, as well as to collect and analyse appropriate data with the aim to demonstrate the suitability and the achievement of a desired quality levels. The analysis of data provides information about conformity to product requirements but also related to characteristics and trends of processes and products, including opportunities for preventive actions. This last aspect – the preventive action – depends also on the ability to monitor both the functionality of the product and the capability of the process to fulfil requirements. In this scenario IMEKO TC 10 aims to represent a reference point for scientists and researchers. It can be regarded as a forum for exchanging knowledge and sharing ideas concerning methods, principles, instruments and tools, standards and industrial applications on Technical Diagnostics as well as their diffusion across the scientific community. In this issue two main aspects are considered as a result of different research activities presented in the Workshop. First, the impact of technical diagnostics on the product performances is considered. For this topic different points of view and proposals in the field of fault diagnosis are presented by the authors. B. Aubert et al. deal in [1] with an Extended Kalman Filter based fault detection in Permanent Magnet Synchronous Generators. Being such equipment used often in high technology contexts, it is fundamental to guarantee high performances in terms of reliability and safety. Authors propose a method for inter-turn shortcircuit detection based on the identification of the shortcircuited turns ratio in a faulty PMSG model expressed in Park frame. Several tests are also implemented in order to demonstrate robustness and sensitivity of the approach. In the field of testing for electronic devices an interesting contribution is proposed by D. Zaleski and R. Zielonko in [2]. The paper concerns the testing of analog circuits and blocks in mixed-signal Electronic Embedded Systems (EESs) by means of the Built-in Self-Test (BIST) technique. In particular, two testing functions are performed:

Multiphysics modelling of the coupled behaviour of precision-guided projectiles subjected to intense shock loads

Precision-guided projectiles (PGPs) typically deployed in smart munitions are operated and guided by highly sophisticated embedded electronic systems (EES). These PGPs are subjected to severe shock loads resulting from the ignition of the propellant during their launch. These shock loads, which are typically characterised by high intensity, short duration and wave reflections at varied frequencies, often lead to the failure of the EES. It is the objective of this work to conduct a comprehensive multiphysics analysis of the launch process of PGPs accounting for coupling and interaction effects between the different media (propellant, PGP, confined volume and free space). Specifically, we investigated the entire launch process that include the ignition of the propellant to observe local and global features of the setback, set forward pressure and acceleration histories using explicit axisymmetric Lagrangian–Eulerian finite element simulations. In this work, we also examine the severity and frequency of the reflected waves as well as the springback of the PGPs resulting from these local oscillations as they exit the muzzle. In addition, the flight state transition due to muzzle exit in terms of pressure and flow velocity is also discussed. Our results reveal the complex phenomena associated with the dynamic response of the PGPs and pressurization process resulting from the ignition of propellant during launch that are characterized by high oscillatory pressure profiles and projectile springback.

Digital discrimination of neutrons and γ rays with organic scintillation detectors in an 8-bit sampling system using frequency gradient analysis

The feasibility of using frequency gradient analysis (FGA), a digital method based on Fourier transform, to discriminate neutrons and γ rays in the environment of an 8-bit sampling system has been investigated. The performances of most pulse shape discrimination methods in a scintillation detection system using the time-domain features of the photomultiplier tube anode signal will be lower or non-effective in this low resolution sampling system. However, the FGA method using the frequency-domain features of the anode signal exhibits a strong insensitivity to noise and can be used to discriminate neutrons and γ rays in the above sampling system. A detailed study of the quality of the FGA method in BC501A liquid scintillators is presented using a 5 G samples/s 8-bit oscilloscope and a 14.1 MeV neutron generator. A comparison of the discrimination results of the time-of-flight and conventional charge comparison (CC) methods proves the applicability of this technique. Moreover, FGA has the potential to be implemented in current embedded electronics systems to provide real-time discrimination in standalone instruments.

Application of Complementary Signals in Built-In Self Testers for Mixed-Signal Embedded Electronic Systems

This paper concerns the implementation of shape-designed complementary signals (CSs), which were matched to the frequency characteristic of the circuit under test, in built-in self testers (BISTs), dedicated to mixed-signal embedded electronic systems for testing their analog sections. The essence of the proposed method and solution of CS BIST is low-cost realization on the base of hardware and software resources of microcontrollers that were used in contemporary embedded systems. This paper presents a description and a theoretical basis of known bipolar CSs and unipolar CSs proposed by the authors, results of investigations of metrological properties of CSs, and a solution of CS BIST and its experimental verification on the examples of testing second- and fourth-order Butterworth filters.

Bayesian surrogates for integrating numerical, analytical, and experimental data: application to inverse heat transfer in wearable computers

Wearable computers are portable electronics worn on the body. The increasing thermal challenges facing these compact electronics systems have motivated new cooling strategies such as transient thermal management with thermal storage materials. The ability of building models to assess quickly the effect of different design parameters is critical for effectively incorporating innovative thermal strategies into new products. System models that enable design space exploration are built from different information sources such as numerical simulations, physical experiments, analytical solutions and heuristics. These models, called surrogates, are nonlinear, adaptive, and suitable for system responses where limited information is available and few realizations of experiments or numerical simulations are feasible. This paper applies a Bayesian surrogate framework to estimate values for unknown physical parameters of an embedded electronics system. Physical experiments and numerical simulations are performed on an embedded electronics prototype system of a wearable computer. Numerical models for the experimental prototype, which involve five and three unknown parameters, are implemented with and without thermal contact resistances. Through the use of orthogonal arrays and optimal sampling, an efficient exploration of the parameter space is performed to determine thermal conductivities, thermal contact resistances and heat transfer coefficients. Surrogate models are built that combine information obtained from numerical simulations, experimental model measurements and a thermal resistance network. The integration of several information sources reduces the number of large-scale numerical simulations needed to find reliable estimates of the system parameters. For the embedded electronics case, the use of prior information from the thermal resistance network model reduces significantly the computational effort required to investigate the solution space.