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Current systems such as satellites, aircrafts, automobiles, turbines, wind power generators and traffic controls are becoming increasingly complex and/or highly integrated as prescribed by the SAE-ARP-4754 Standard. Such systems frequently require accurate generation, distribution and time or phase synchronization of signals with different frequencies that may be based on one reference signal and frequency. But the environment fluctuations or the non-linear dynamics of these operations cause uncertainties (skew and jitter) in the phase or time of the reference signal and its derived signals. So, techniques to reduce those causes or their effects are becoming important aspects to consider in the design of such systems. The PLL techniques are useful for establishing coherent phase or time references, jitter reduction, skew suppression, frequency synthesis, and clock recovery in numerous systems such as communication, wireless systems, digital circuits, rotors, and others.

In this work we discuss the fault avoidance and the fault tolerance approaches for increasing the reliability of aerospace and automotive systems. This includes: the basic definitions/concepts (reliability, maintainability, availability, redundancy, etc.), and characteristics (a priori analysis, a posteriori analysis, physical/hardware redundancy, analytical/software redundancy, etc.) of both approaches, their mathematical background and models (exponential, Weilbull, etc.), their basic theory, their methods and techniques (fault trees, dependence diagrams, Markov chains, etc.), some of their standards (SAE-ARP4761, AC 25.1309, etc.) and simulation environments (Cafta, etc.), and their applications to the reliability analysis and reliability improvement of aerospace and automotive vehicles. This is illustrated by some examples driven from the aerospace and automotive industries.

This paper presents the preliminary results of an "a posteriori" exercise of application of a Requirements Traceability Automation Tool (RT tool) to a set of documents. The documents have been prepared according to established Space System Engineering methodologies and with attention to text quality, but without attention to requirements traceability because the processes and methodologies used during their preparation predates the emergence of the processes and methodologies developed by Requirements Engineering (RE). This study is intended to determine some of the benefits of using a RT tool when compared with the previously used processes and methodologies. The set of documents under scrutiny have been prepared in the frame of the development of the CBERS-3 satellite (China-Brazil Earth Resources Satellite) and is composed of system, subsystem and equipment specification and covering documents related to the Electrical Power Subsystem (EPS) of the satellite.

This paper presents some techniques for fault diagnosis in aerospace and automotive systems. A diagnosis technique is an algorithm to detect and isolate fault components in a dynamic process, such as sensor biases, actuator malfunctions, leaks and equipment deterioration. Fault diagnosis is the first step to achieve fault tolerance, but the redundancy has to be included in the system. This redundancy can be either by hardware or software. In situations in which it is not possible to use hardware redundancy only the analytical redundancy approach can be used to design fault diagnosis systems. Methods based on analytical redundancy need no extra hardware, since they are based on mathematical models of the system.

This paper presents an analytical and simulation study of the stabilization and improvement of the active vibration damping of a system modeled by a simple analog harmonic oscillator driven by discrete time control. Initially, this control is the Bilinear (or Tustin) s-z mapping equivalent of a continuous-time asymptotically stable Proportional plus Derivative (PD) control. It is tested with high values of the sampling period. It is shown that all classical mappings (Tustin, Schneider, etc.) tested may instabilize the system. To circumvent this, we propose and use a new (ST1) mapping that behaves better than the classical ones tested under the same conditions. We also model an active discrete control of a suspension of a vehicle, and compare the performance between the PD controllers designed by Bilinear and by the new (ST1) S-Z mappings, for this example.

In this work we discuss some types of simulators and simulations, their characteristics and applications to the simulation and control of aerospace vehicles. This includes: the basic definitions, types and characteristics of simulators and simulations (physical, computational, hybrid, etc.; discrete events, discrete time, continuous time, etc; deterministic, stochastic, etc.) their basic compromise (simplicity × fidelity), their man-machine interfaces and interactions (virtual, constructive, live, etc.), their evolution law (time, events, mixed, etc.), their architectures (“standalone”, PIL, HIL, MIL, DIS, HLA, etc.), their environments (discrete, continuous, hybrid, etc.) and their applications to the simulation and control of aerospace vehicles. This is illustrated by some examples driven from the aerospace industry

In this work we discuss some types of simulation environments and laboratories, their characteristics and applications to the simulation and control of aerospace vehicles. This includes: the basic definitions, types and characteristics of simulators and simulations (physical, computational, hybrid, etc.; discrete events, discrete time, continuous time, etc; deterministic, stochastic, etc.) their basic compromise (simplicity × fidelity), their man-machine interfaces and interactions (virtual, constructive, live, etc.), their evolution law (time, events, mixed, etc.), their architectures (“stand-alone”, PIL, HIL, MIL, DIS, HLA, etc.), and especially, their environments (discrete, continuous, hybrid, etc.) and laboratories (physical, computational, hybrid, etc.), and their applications to the simulation and control of aerospace vehicles. This is illustrated by some examples driven from the aerospace industry.

In this work we discuss some types of simulation architectures and standards, their characteristics and applications to the simulation and control of aerospace vehicles. This includes: the basic definitions, types and characteristics of simulators and simulations (physical, computational, hybrid, etc.; discrete events, discrete time, continuous time, etc; deterministic, stochastic, etc.) their basic compromise (simplicity x fidelity), their man-machine interfaces and interactions (virtual, constructive, live, etc.), their evolution law (time, events, mixed, etc.), their architectures (“stand-alone”, PIL, HIL, MIL, DIS, HLA, etc.), their standards (OMBA, SIMNET, ALSP, DIS, HLA 1.3, HLA 1516, ASIA, AP2633, etc.) and their applications to the simulation and control of aerospace vehicles. This is illustrated by some examples driven from the aerospace industry

Currently, the use of Global Navigation Satellite Systems-GNSS has been widely disseminated for the most different applications, from the aeronautical navigation to the car traffic, being the Global Positioning System-GPS the most used system for such objectives. New applications have presented challenges in terms of the main requirements associated to such systems, namely: precision, reliability, availability, continuity and integrity. It is because proposed solutions, such as satellite or ground-based augmentation systems, depend on signals provided by the GNSS satellite constellation. It constitutes a limitation for using such systems for position and velocity estimations. On other hand, Inertial Navigation Systems-INS, being independent of external signals, have a big potential to be applied on these circumstances; furthermore, they present characteristics that may be considered complementary to the GNSS.

Currently, the use of Global Navigation Satellite Systems-GNSS has been widely disseminated for the most different applications, from the aeronautical navigation to the car traffic system, being the Global Positioning System-GPS the most used system for such objectives. New applications of such systems have presented more demanding requirements in terms of precision for the position and velocity provided by these systems. Some solutions, as the precision augmentation systems based on satellite or ground improve the precision of the position and velocity estimates. However, the sampling rate of these systems is not substantially improved. Therefore, it constitutes a major limitation of such systems for the position and velocity estimates during high acceleration transients. On other hand, Inertial Navigation Systems- INSs present superior performance under these circumstances.

The realization of modern systems subjected to automatic control, such as aircraft, automobiles, satellites, rocket launchers, cargo and military ships, and so forth; increasingly assume, within its very set of requirements, the task of providing better dependability, i.e.: safety, reliability, and availability altogether. Towards this demand, fault-tolerant control greatly meets such growing demand of dependability, by its ability of recognizing the occurrence of potentially hazardous/hazardous faults within the overall (closed-loop) system, and by taking remedial action whenever necessary/mandatory. The process of fault tolerance can be segregated into two fundamental steps: (1) that of fault diagnosis, comprising fault detection-isolation-identification, and, (2) control adjustment/reconfiguration. This paper focuses on the second step, of control adjustment/reconfiguration.

One challenge that the space, aeronautical and automotive industries are facing today is the fast growing number of vehicles versus the slowly growing number of useful orbits, routes, and speedways. Furthermore, the adoption of “free-flight”, “speed-drive”, etc. policies in the near future will only aggravate it. All these factors increase the risk of collisions and the frequency of deviation maneuvers to avoid them. But they also create the opportunity to devise policies to mitigate such problems, including algorithms to propagate the uncertainties in vehicle motions and to predict the risk of their collisions. This work discusses the development and simulation of an algorithm for the propagation of navigation uncertainties in the trajectory of aerospace vehicles, to minimize the risk of collisions. The scenario of Satellites Formation Flying shall be used for the simulations, with focus on the prediction of the collision probability.

A major trend in modern aerospace and automotive systems is to integrate computing, communication and control into different levels of the vehicle and/or its supervision. A well fitted architecture adopted by this trend is the common bus network architecture. A Networked Control System (NCS) is called when the control loop is closed through a communication network. The presence of this communication network introduces new characteristics (sharing bus, delays, jitter,etc) to be considered at design time of a control system. This work focuses on the effect of sharing bus between the control system and the other devices connected to the bus foreigner to control. These last devices are called interferences. We intented to show, through simulations, the influence of sharing bus on real time control systems performance. To compare effects, we choose the CanBus protocol where the medium access control is event driven; and the TTP protocol where the medium access control is time driven.

The measure of time intervals with relatively high accuracy (of 1 milisecond, at least) in PC computers is a relatively hard task to solve. But this is essential for the digital simulation, with sensors in the loop, of fast control systems. This work allows the reading of the programmable internal timer 8253 present in a typical PC, reaching 1 ms resolution, at least, through a C high level language routine. The determination of the angular velocity of a 53M2-30H Contraves 3-axis dynamic simulator used in that simulation was improved by the use of this work, allowing the acquisition of consecutive measures of angles and angular velocities with a time interval smaller than 10 ms in some cases. Using this routine and other simulator control and monitoring softwares we estimated the angular velocity faster (100 ms × 210 ms)and better than the simulator Rate Readout Module, and used it in a fast real time control simulation.

This works presents the generation and customization of real time code for embedded controllers using a modeling and simulation environment. When the controller model is considered satisfactory, the developers can use a code generation tool to build a real time source code capable to be migrated to an embedded target processor. The code generation tool used is capable to generate real time code in ANSI C or ADA 95 languages. This process can be customized to adequate to a target processor and/or a Real Time Operating System (RTOS). The code customization can be achieved using a specific Template Programming Language (TPL) that specifies how the code will be generated. This technique makes it possible the instantiation of real time embedded controllers code using the same controller model to a wide variety of target processors and/or RTOSs.

This work presents the distributed simulation of the longitudinal mode of an aircraft by using the DoD High Level Architecture (HLA). The HLA is a general-purpose architecture for simulation reuse and interoperability. This architecture was developed under the leadership of the Defense Modeling and Simulation Office (DMSO) to support reuse and interoperability across the large numbers of different types of simulations developed and maintained by the DoD. To do this, the transfer function of the longitudinal mode of a hypothetical aircraft was implemented by means of a SystemBuild/MATRIXx model. The output of this model was connected to a Run-Time Infrastructure (RTI) and monitored on a remote computer. The connection between the model and the RTI was implemented by using a wrapper which was developed in C++. The HLA RTI implementation used in this work was the poRTIco.

This paper presents the first of four parts of the academic design of an Attitude Control System (ACS) for the Multi-Mission Platform (MMP) and its migration to a Real Time Operating System. The MMP is a three axis stabilized artificial satellite now under development at the National Institute for Space Research (INPE). Such design applied some software engineering concepts as: 1)visual modeling; 2)automatic code generation; 3)automatic code migration; 4)soft real time simulation; and 5)hard real time simulation. A block diagram based modeling and a virtual time simulation of the MMP ACS in its nominal operational mode were built in the MatrixX 7.1 environment satisfying the three axis pointing and stabilization requirements. After that, its AutoCode module was used to generate C ANSI code representing the block diagram model. Time characteristics were added to the ACS generated code to make it the real time control software of MMP nominal operational mode.

In this work we discuss current trends driving the aerospace and automotive systems architectures. This includes trends as: 1) pos-globalization and regionalization; 2) the formation of knowledge oligopolies; 3) commonality, standardization and even synergy (of components, tools, development process, certification agents, standards); 4) reuse and scalability; 5) synergy of knowledge and tools convergence; 6) time, cost and quality pressures and innovation speed; 7) environmental and safety issues; and 8) abundance of new technologies versus scarcity of skilled manpower to apply them.

Internet of Things (IoT) for real-time applications are demanding more and more high performance, precision, accuracy, modularity, integration, dependability and other attributes in a complex and/or highly integrated environment. Such systems need to provide coordination among the integrated components (e.g. sensors, computer, controller and networks) for enabling the application to take real-time measurements and to translate into controllable, observable and smart actions with strict timing requirements. Therefore, coordination and synchronization are required to ensure the controllable, observable and smart actions of real-time IoT systems. This paper shows the design issues about the coordination and synchronization in the internet of things applied to real-time applications. We also show the current coordination and synchronization techniques and their design issues when applied to IoT systems.

Many control systems switch between control modes according to necessity. That is often simpler than designing a full control to all situations. However, this creates new problems, as determining the composed system stability and the transient during switching. The latter, while temporary, may introduce overshooting that degrade performance and damage the plant. This is particularly true for the MultiMission Platform (MMP), a generic service module currently under design at INPE. Its control system can be switched among nine main Modes of Operation and other submodes, according to ground command or information coming from the control system, mainly alarms. It can acquire one and three axis stabilization in generic attitudes, with actuators including magnetotorquers, thrusters and reaction wheels.