A GROUND LOOP ATTITUDE CONTROL SYSTEM FOR ANIK B

Inserting a satellite into different orbit of injection orbit require an orbital maneuver. In addition, the orbit maneuver needs a suitable control of upper stage. Providing required angles is the duty of this control and it must be able to come over disturbances. This paper, with looking over Attitude Control Systems (ACS) used in upper stages, introduces an algorithm for design and sizing of upper stage`s ACS considering requirements and constraints. The algorithm derives required ACS propellant mass, tanks value, feeding pressure, amount of thrust, combustion chamber pressure and total mass of ACS. Presented algorithm needs minimum inputs and estimates the outputs using accuracy experimental functions and scientific theorems. Finally the algorithm is validated by some real cases.

This paper proposes and substantiates the improvement of the on-board vibration control system of aircraft engines to expand the system’s functional capabilities and provide multi-class diagnostics based on multi-level processing of vibration signals. The possibility of diagnosing initial crack-like damage to the rotor shaft and impeller blade is considered, as well as the possibility of detecting such operational violations of the engine's regular modes, such as minor imbalance, ingress of small and medium-sized foreign objects, and grinding of the impeller blades. Such damages and disturbances do not lead to increased vibration of the rotary harmonics and are not detected by traditional analysis methods. For multi-class diagnostics, multi-level processing of vibration signals based on various combinations and/or sequential application of time-frequency analysis, multi-spectral analysis, and fractal analysis methods were used. This work proposes the structure of a subsystem of multi-class diagnostics as part of the standard on-board engine vibration control system in steady-state and transient operating modes, as well as algorithms for detecting initial crack-like damages of rotating elements and disturbances in standard operating modes. As diagnostic signs, the following are used: the Hurst index of the vibration signal in the region of subharmonic resonance in the transient mode (for the diagnosis of the initial transverse crack of the rotor shaft); dimension of Minkowski time-frequency spectra of vibration signals in stationary and transient modes (for diagnosing the initial crack of the impeller blade); simultaneous use of the Hurst index of samples of vibration signals and dimension of Minkowski estimates of the module of the bispectrum of vibration signals (for diagnosing violations of standard operating modes). The developed software algorithms use received and pre-processed signals from vibration and engine speed sensors, provide the determination of the mode of vibration disturbance, perform time-frequency, bispectral, and fractal analysis in the sequence determined for each diagnostic task, calculate the value of the diagnostic feature and compare it with the reference value, based on the results of the comparison, establish the appropriate diagnosis and submit it to the decision-making system. The proposed algorithms are intended for use in the corresponding blocks of the multi-class engine diagnostic subsystem.

The paper is dedicated to describing a method for increasing the reliability and survivability of on-board control systems. The object of the research is a class of aircraft — cruise missiles, which are considered one of the most promising weapon systems. The article analyzes modern structures of on-board control systems that ensure high reliability of such systems. The study focuses on analyzing four-channel fault-tolerant systems for on-board control complexes with enhanced survivability, which ensure high operational reliability of the complexes over extend-ed periods without physical maintenance while maintaining resistance to equipment malfunc-tions and failures. Additionally, the paper examines its prototype — a three-channel system with synchronization outputs. Both positive and negative aspects of these systems are highlight-ed, noting their high level of hardware redundancy. For short-lifespan aircraft, such as cruise missiles and similar systems, the authors propose a two-channel quasi-bridge structure (QBS) for the on-board control system, featuring block-level redundancy and reconfiguration. In gen-eral, the QBS represents a system consisting of a sequential connection of redundant nodes with equal reliability. When one of the functional subunits of a redundant node fails, the control and reconfiguration scheme excludes it from the computational process and reconfigures the system structure in a non-stop mode. As a tool for studying the reliability of the on-board system, a probabilistic-physical method (PP-method) has been used, which is based on a diffusive distri-bution of time-to-failure (DN-distribution), specifically formalized for the assessment and pre-diction of the reliability of electronic, electrical, and electromechanical elements and systems. While maintaining the level of redundancy characteristic of all two-channel structures, the pro-posed two-channel redundant QBS, with its decomposition of channels into equally reliable re-dundant nodes, leads to an increase in the probability of failure-free operation (the R-effect), which becomes more significant as the number of nodes increases. The paper also describes the principle of placing functional subunits of the QBS, providing an additional effect — the over-all increase in system survivability.

The National Aeronautics and Space Administration (NASA) and the National Science Foundation (NSF) commissioned a panel of scientists and engineers in 1997 to benchmark the global status of commercial communications satellite technology, markets and regulatory and policy issues. After visiting or interviewing over 60 manufacturing, R&D laboratory, service provider and government institutions in North and South America, Europe and Asia, the review panel concluded as follows: 7.3cm\begin{itemize} \item Many European and Asian governments are increasing their satellite communications R&D programs and supporting demonstrations and space marketing efforts, relative to the US. \item The US is currently the leader in new technology and its insertion into commercial satellite systems, but ambitious foreign efforts threaten this position. \item Global commercial satellite communications is a large and rapidly growing business. \item New technology is being inserted into satellites at an increasingly rapid pace with an increasing number of international participants. \item Aerospace communications companies, worldwide, are consolidating their efforts and are expanding into the end user service business. \item The ‘Direct‐to‐End User’ mass consumer satellite service industry has the potential to be quite large and is changing the way satellites are manufactured and deployed and is creating a potentially large satellite terminal industry. \item Satellite manufacturing is increasingly becoming a design, assembly and test operation with parts and sub‐systems obtained from global suppliers. \end{itemize} 7.3cm \begin{itemize} \item This increased use of satellites for communications services is creating a shortage of spectrum and orbital slots and is resulting in spectrum utilization conflicts with terrestrial wireless service providers. \item Future development of commercial satellite communications is dependent on the resolution of key regulatory, trade, spectrum, inter‐operability and standards issues and government leadership is vitally needed. \item There are opportunities for international cooperation to facilitate the development of satellites technologies, systems, standards and protocols. \end{itemize} There is concern that unless several issues are addressed, particularly an increase in long term oriented R&D and trade and regulatory issues, the US may experience a deterioration of its leading position in the manufacture of satellites for global service providers and the initiation of new services, much in the way that it lost its leading position in the launch of commercial satellites.

The advent of satellite communications brought a new era to the TV industry. In the early years, however, the use of satellites was quite costly and limited by the modest capacity of the first commercial communications satellites. However, the evolution of satellite technology and the development of satellite aggregators, such as Brightstar, Wold Communications, Bonneville, IDB, Keystone, and Globecast, led to a sharp reduction in the cost of satellite television. The development of full-time, annualized satellite transponder charges – as opposed to per-minute fees – was also critical to the development of much lower satellite television fees. P. Marshall (*) Royal Television Society, London, UK e-mail: pmsatellites@btinternet.com # Springer Science+Business Media New York 2015 J.N. Pelton et al. (eds.), Handbook of Satellite Applications, DOI 10.1007/978-1-4614-6423-5_85-2 1 The evolution of digital television services was another important breakthrough. Instead of the one or two television channels per transponder with analog systems, it became possible to derive up to 18 channels per transponder. Digital transmission speeded up the evolution of domestic television satellite systems and played a key role in the growth of direct-to-home satellite broadcasting. The development of satellite-based video systems was not seamless and encountered periods of major market difficulties. One of the most prominent market development issues was the failure of early direct broadcast satellite systems (or BSS in the terminology of the ITU). However, DBS (or BSS) satellite markets are now well established in international, regional, and domestic markets. They are not only highly successful but represent by far the largest single satellite market in terms of revenues. Most recently, there has been a rapid growth of high-definition television (HDTV) service via satellite. These satellite services compete with coaxial cable and fiber-optic-based CATV systems. The economics of satellite television are quite different from terrestrial networks because once a direct broadcast satellite system is launched and operational there is very little incremental cost beyond the consumer terminal needed to receive service. The advent of new digital interface standards known as digital video broadcast with return channel service (DVB-RCS) and Digital Over Cable Service Interface Standard (DOCSIS) have allowed the rapid development of digital television over satellite and cable systems. DOCSIS is now widely used for both satellite and cable television systems. These digital standards, together with high-power fixed satellite systems and broadcast satellite systems – that by definition have high power – allow not only the distribution of a large number of video channels to consumers but also low-cost distribution of high-speed digital data service to both home consumers and businesses. These digital satellite video systems can be – and indeed are – used to provide broader band digital services to the “edge” of digital networks at low cost. Thus DBS and higher powered FSS satellite systems are now being used to provide commercial broadband data services to business as well as broader band digital services to remotely located consumers.

This paper discusses optimal three-dimensional flight control of a supersonic fighter through an onboard automatic guidance and control system. This system is simulated to check the speed requirements of the algorithms to be solved before being implemented in real hardware. A very-high-speed digital computer is used for this time-critical simulation. In the simulation optimal trajectories are generated in real time, on line. Results obtained from the particular problem of a real-time, online minimum-time supersonic chandelle with prescribed final point are displayed.

A brief description of the design concept, structure and performance of the onboard control system (AOCS) of the “Navigator” satellite platform, on the basis of which the spacecraft “Electro-L’ and “Spektr-R” are designed, is presented. The test-flight results of the AOCS attitude accuracy are given. Approaches to the further development of the onboard control equipment for advanced spacecraft are determined and presented.

This paper describes the structural dynamic characteristics of a NASA reference space station configuration as defined in the November 1987 Space Station Program - Systems Engineering and Integration Engineering Data Book. The modes and frequencies of the station below 2.0 Hz were obtained and selected results along with rigid body properties are presented. A three-axis attitude control system using control moment gyros responding to attitude and attitude rate signals is used to regulate the orientation of the station. The stability of the control system with non-collocated sensors is investigated for both compensated and uncompensated control signals. Results from a closed-loop simulation of a commanded attitude change about three axes, and from a closed-loop simulation of the response of the station to an externally applied unit force impulse at the docking port are presented. These simulation results are used to evaluate the possible degree of control/structures interaction which could occur during normal operation of the station.

The construction of the third generation of the Chinese BeiDou navigation satellite system (BDS), which provides global positioning, navigation, and timing (PNT) services, will be completed in 2020. As BDS satellites contain the geostationary orbit (GEO), inclined geosynchronous (IGSO), and medium earth orbit (MEO), orbital manoeuvres occur more frequently. Thus, orbit manoeuvre detection is important for continuous and reliable PNT services. A BDS orbit manoeuvre detection method based on the combination of global positioning system (GPS) and BDS observations is proposed in this study. The standard deviations of the observation residuals of the epoch-differenced velocity estimation of the single BDS system and combined GPS + BDS system were compared to determine the beginning and end of the orbit manoeuvre. The results show that the orbital manoeuvre leads to a position, velocity, and receiver clock error bias of approximately tens to hundreds of metres, several centimetres per second, and tens to hundreds of metres, respectively. Based on the proposed method, the start and end times can be detected in real time and the usable observation time can be extended by >157 min.

The paper is dedicated to the overview of the autonomous ship onboard control system functionality. The paper is dedicated to autonomous maritime navigation, i.e. to planning a safe and optimal route for an autonomous ship amid the absence of crew on board and to handling an autonomous ship when underway, ensuring seaworthiness and route correctness. Moreover, the paper describes communications of several autonomous ships and autonomous and ordinary ships to infer a collective decision on how to pass safely through a particular area. Since it is expected that autonomous ships are going to be equipped with dozens of sensors and detectors, the paper describes remote monitoring of an autonomous ship when underway. Since an autonomous ship highly depends on its onboard control system, the paper also pays attention to the robustness of the system. The paper suggests evolutionary computations as a solution for the route planning problem because this approach enables to perform multicriteria optimization of a set of solutions simultaneously. For autonomous ship handling and seaworthiness control, the paper suggests machine learning techniques because these techniques can solve problems in case of uncertainty and the environmental mutability. For inter-ship communications, the paper suggests distributed consensus algorithms, widely used in parallel and distributed computation systems. To ensure the onboard control system robustness, the paper suggests the actor approach that represents that the entire software system consists of a set of elementary agents communicating in the distributed computational environment.

In Fall 2021, SpaceLink Corporation was selected by the Center for the Advancement of Science in Space (CASIS), manager of the International Space Station (ISS) U.S. National Laboratory, for a demonstration of its end-to-end space data relay service. SpaceLink will provide secure, continuous communications between terrestrial operators and an optical terminal on the ISS, enabling real-time, high-throughput connectivity for the onboard crew, systems, and various science experiments. In a highly competitive process, made available for companies and research teams to propose technology development concepts operating in Low Earth Orbit (LEO), CASIS selected the SpaceLink concept. With this selection, SpaceLink will advance its flight project in collaboration with the ISS National Laboratory. The SpaceLink relay network will succeed and exceed NASA's Tracking and Data Relay Satellite System (TDRSS) with unprecedented capacity that leverages the latest optical communications technology advances. Demand for high-throughput, continuous orbital connectivity continues to grow with the ongoing proliferation of LEO satellites. SpaceLink's network is designed to help close the business case for Earth observation companies, commercial space stations, satellite services, launch vehicles, and space tugs. It also meets the requirements of the U.S. Government and close allies that are leveraging real-time, secure communications solutions. The SpaceLink ISS demonstration will validate a 10 Gigabit per second (Gbps) optical terminal communication link for real-time voice, video, and data relay for the ISS. Axiom Space, SpaceLink's implementation partner, will leverage its expertise in working with NASA and the ISS National Laboratory to support the SpaceLink payload mission integration, launch, and operations. Axiom will support SpaceLink as a liaison with NASA and will lead safety reviews to ensure SpaceLink hardware meets all ISS requirements. The SpaceLink-ISS Connectivity End to End Demonstration (SLICED) will demonstrate the highest data rates that can be achieved between SpaceLink relay spacecraft in Medium Earth Orbit (MEO) and the ISS, an example user satellite in LEO. The demonstration will include MEO-LEO edge case geometries where the relative range rates between the satellites are the highest and required contact acquisition times are shortest. SpaceLink's real-time gigabit user data rates are possible via optical inter-satellite communications between spacecraft, as well as high-bandwidth QN-band communications between SpaceLink's relay spacecraft and terrestrial gateways. SpaceLink has designed an innovative system architecture, implementing high-security services and continuous availability so that satellite data is available in real time when it matters the most. This study will discuss the technical foundation behind SpaceLink's ISS demonstration infrastructure.

This paper conceptualizes the main principles of comprehensive software verification for an onboard spacecraft control system. An optimal comprehensive verification strategy for onboard softwareis selected by rigorously stating and solving the corresponding optimization problem. Software verification methods with functional correctness indicators are proposed.

During an impulsive orbital maneuver, thrust vector misalignment from the center of mass (C.M) generates a large exogenous disturbance torque that results in attitude deviation. This paper aims not to use the reaction control system (RCS) for the spacecraft attitude control. In order to reject the large disturbance very fast, a new control system is proposed. In this method, the large disturbance torque is rejected quickly while the RCS is not employed. The control system is based on one degree of freedom (1DoF) gimbaled-thruster, spin-stabilization, and two control moment gyros (CMG). The nonlinear two-body dynamics of the mentioned spacecraft is formulated. Because RCS is not used, this method is an efficient and implementable method for attitude control of small spacecraft. Numerical simulation shows that thrust vector deviation converges to zero despite disturbance torques. By this method, the disturbance is rejected very fast; thus an accurate orbital velocity change can be obtained. This method can eliminate the initial attitude deviation easily in addition to disturbance rejection. The results show the good performance and superiority of the proposed method compared to some other thrusting maneuver methods.

An onboard control system (OBCS) that controls the operation of a high-speed train is a distributed control system that centrally supervises and controls a distributed system of independent units. A complicated process of design, implementation, and test is needed to develop this system. The OBCS and its control algorithm are designed and verified by using the computer-aided software engineering (CASE) tool before it is implemented. Its functions are verified by the OBCS simulator. This paper presents the verification process for the Korean high-speed train.

This chapter provides information concerning the use by governments of military and commercial satellites systems for strategic and defense purposes. It discusses dedicated communications satellite systems designed for particular uses and the so-called dual use of commercial systems to support military and strategic purposes. It explains various pathways that can be followed by governments to obtain communications satellite services to support military uses. These paths include: (1) dedicated satellites, (2) hybrid satellites (both military and commercial payloads on a single satellite), (3) shared satellite facilities via A. Stanniland (*) Paradigm Secure Communications Ltd, Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2AS, UK e-mail: andrew.stanniland@paradigmsecure.com D. Curtin Eagle Group Partners, 14105 Arctic Avenue, Rockville, MD, 20853, USA e-mail: dns.crtn@gmail.com J.N. Pelton, S. Madry, S. Camacho-Lara (eds.), Handbook of Satellite Applications, DOI 10.1007/978-1-4419-7671-0_8, # Springer Science+Business Media New York 2013 187 intergovernmental agreements, (4) guaranteed long-term leases, (5) ad hoc leases of capacity on demand, and (6) a long-term partnership between a government and a commercial partner as is the case with the Skynet 5 program in the United Kingdom. In this chapter the authors will also examine how various countries obtain their national satcom, how and why commercial capacity has become, and will continue to be, a significant part of national satcom capabilities. It will examine the present and future contracting approaches and procedures used in various countries, but primarily in the United States and other NATO countries. Finally there will be a discussion of the issues involved when nations decide between purchasing nationally owned satellites and leasing capacity commercially.