Space Vehicle Systems Research Articles

Overview of Bridge Crane Control

This paper summarizes the research hotspot of underactuated mechanical system in nonlinear control field, and emphasizes its wide application in practical engineering, including space vehicle, inverted pendulum and navigation system. The Chinese government has supported the construction crane industry through a series of policies and regulations, providing guidance for its safe production and technical specifications. In the context of social development, the application demand of bridge gantry cranes in narrow environments is increasing, and the future development trend will focus on the direction of intelligence, science and technology and humanization. In recent decades, the research results on the positioning and pendulum of bridge crane at home and abroad are divided into open loop and closed loop control methods, and the control methods are described in detail in this paper.

Time-Optimal Control of a Multidimensional Integrator Chain With Applications

This letter studies the time-optimal control problem for a chain of multidimensional integrators subject to convex state and input constraints. It is shown that, by performing a suitable change of variables, this problem can be cast as a single convex program for certain realizations of the boundary conditions. For general realizations, the problem is nonconvex. A constructive procedure based on the solution of a sequence of convex problems is proposed in order to approach asymptotically a global optimum. The proposed approach is demonstrated on three applications involving aerial and space vehicle systems.

Terminal Sliding Mode Control Allocation for Nonlinear Systems

In this paper, the problem of tracking control is studied for a class of nonlinear systems with actuator faults/failures. The control strategy has two steps. In the first step, a virtual control input is found using terminal sliding mode control which can easily tackle the output tracking control problem in a finite time. In the second step, control allocation (CA) transforms the virtual control signals to the real-control inputs. The CA problem is solved using a neural network which satisfies control constraints and during faults or failures redistributes the control signals to the healthy actuators. The effectiveness of the proposed control approach is demonstrated by the simulation results of the near space vehicle system.

Active Noise Cancellation using Online Wavelet Based Control System: Numerical and Experimental Study

Reaction wheels (RWs) used for attitude control of space vehicle systems usually encounter with undesired wide band noises. These noises which significantly affect the performance of regulator controller must tune the review or review rate of RWs. According to wide frequency band of noises in RWs the common approaches of noise cancellation cannot conveniently reduce the effects of the noise. Therefore, the advanced analyzer of frequency domain signal processing such as wavelets must be used to realize the noise cancellation. In this regards, only the online application of wavelets can be practical. In this paper, an online active noise canceller based on online wavelet theory is employed to omit the effects of undesired noise. In this way, dynamic identification of a RW as well as wavelet delay compensation are used simultaneously to design an active noise cancellation system. Numerical and experimental investigations of KNTU test setup as a hard ware in the loop system show the preferences of the proposed method of online noise cancellation.

Higher Order Sliding Mode Control for a Class of MIMO Systems<sup></sup>

A higher order sliding mode control algorithm is proposed to design and analyze for a class of MIMO nonlinear systems with unknown nonlinearities. The proposed control scheme based on geometric homogeneity and sliding mode control provides a general approach to design controller for near space vehicle system. Simulation example results demonstrate the advantages of the strategy.

Viscoelastic Response of HTPB Based Solid Fuel to Horizontal and Vertical Storage Slumping Conditions and it's Affect on Service Life

Frequent use of solid fuels as thrust generating energy source in modern day space vehicle systems has created a need to assess their serviceability for long term storage under various conditions. Solid fuel grain, the most important part of any solid fuel system, responds viscoelastically to any loading condition. For the assessment of the service life of any solid fuel system, the solid fuel grain has to be structurally evaluated in applied storage conditions. Structural integrity of the grain is exceptionally significant to guarantee the successful operation of the solid fuel system. In this work, numerical simulations have been performed to assess the mechanical stresses and strains induced in an HTPB based solid fuel grain during service life employing ABAQUS standard FEA software using 4-node bilinear quadrilateral elements. For finite element analysis (FEA), typical 2-D and π/nth axisymmetric section of 5-point (n) star grain geometry is considered. Mechanical loads include the horizontal or vertical 1-g (solid fuel weight) storage condition. The simulation results are compared with the analytical results for the same grain geometry. Analytically measured slump deflections in grain segment at various storage times have been found in good relation with the FEA based simulation results. This proves the validity of the procedure adopted and is helpful in assessment of the service life of solid fuel systems.

Technique for Initialization and Synchronous Setting of Space Vehicle Time with Navigation System Time

Satellite Navigation Systems (SNS) provide Position, Velocity and Time (PVT) services. The SNS is required to maintain its own System Time with high accuracy. To set up the precise System Time, each system component should maintain its own time within a specified limit. In the SNS, the onboard Space Vehicle (SV) time generator is one of the components and it should be set and maintained with few nanoseconds accuracy. To achieve accurate time setting with minimum difference between the ground and onboard SV systems, the onboard time setting should be highly predictable and accurate. This paper proposes an approach to initialize/set the onboard SV Time. The paper also discusses the concept of synchronization of SV Time with System Time with an overall accuracy better than 1 nsec. The proposed technique requires minimum setting time and synchronization steps and there is no need to predict accurate uplink propagation delay and command execution time.

Adapting space vehicle systems to measurement conditions

A method is proposed for stabilizing the operation of a measurement system while adapting it to the on-board measurement conditions.

Some problems of selection and evaluation of the Martian suit enclosure concept

One of the most important tasks for preparation of a future manned mission to Mars is to create a space suit, which ensures efficient and safe operation of the man on the planet surface. The concept of space suit (SS) utilisation on the Mars surface will be determined mainly by the Mars mission scenario. Currently the preference is given to utilisation of robotics with the crew driving a Mars rover vehicle, whereby the suit will be used solely as an additional safety means. However, one cannot exclude the necessity of a durable self-contained stay of the man outside a pressurised compartment, to pick up, for instance, soil samples or do certain repair work in case of an emergency. The requirements to the Mars suit and especially to the personal self-contained life support system (LSS) will depend in many respects on the Mars environmental conditions, the space vehicle system concept and performance characteristics, the airlock and its interface design, the availability of expendable elements for the LSS, etc. The paper reviews principal problems, which have to be solved during development of the Martian suit. A special attention is paid to the issue of suited man mobility during traversing on the planet surface. The paper also reviews the arguments for application of a suit semi-rigid design concept and evaluates potentialities of using certain elements of the existing “Orlan” type suit. The paper presents results of a number of studies on selection of the planetary SS enclosure concept and on experimental evaluation of mobility of the lower torso and leg enclosures in conjunction with a specially designed prototype model (tentative model) of the SS enclosure.

Intelligent flight support system (IFSS): a real-time intelligent decision support system for future manned spaceflight operations at Mission Control Center

The Mission Control Center Systems (MCCS) is a functionally robust set of distributed systems primarily supporting the Space Shuttle Program (SSP) and the International Space Station (ISS) mission operations. Forged around the uniquely complex and demanding requirements of human spaceflight, the MCCS has evolved within the limits of the technological capabilities of the time. The dynamic environment in which MCCS functions has demanded that the systems architecture continue to evolve as well. The MCCS provides the primary means of controlling crewed spacecraft operated by NASA. Flight controllers (FCs) monitor the spacecraft systems through telemetry sent from the spacecraft to the ground and from the ground to the vehicle. FCs utilize several application software to present telemetry data in a variety of output presentations. While most displays simply provide a densely packed screen of telemetry data, only a few provide graphical representations of the vehicle systems' status. New technological advances in user interface design have not penetrated into MCC especially since the SSP and ISS systems were developed when these technologies were not available. The Intelligent Flight Support System (IFSS) described in this paper promotes situational awareness at MCC with an interactive virtual model of the ISS and Space Shuttle combined with data and decision support displays. IFSS also incorporates an intelligent component to model various characteristics of space vehicle systems when predictable results of unknown scenarios are required. IFSS supports FCs in the planning, communications, command, and control operations of the ISS and Space Shuttle by providing knowledge and skills that are unavailable from internal representation.

Electron beam observation opportunity

Ionospheric researchers will have the opportunity to conduct coordinated radio, radar, and optical observations in conjunction with other space‐based electron beam experiments as part of the upcoming Cooperative High‐Altitude Rocket Gun Experiments (CHARGE) 3 rocket flight in November 1988 at White Sands Missile Range (WSMR, White Sands, N.Mex.). The flight will be particularly interesting because of the high power planned for the electron gun (3.5 kV at 5 A), which is based, in part, on technology developments planned for the successful Excede series of rockets.CHARGE 3 is the third in a series of U.S. flights made in collaboration with investigators from Utah State University (Logan), Stanford University (Stanford, Calif.), the Institute for Space and Astronautical Sciences (Sendai, Japan), and the University of Michigan (Ann Arbor). The general objectives for CHARGE 3 are fourfold: to study vehicle charging and diagnosecontributory effects at higher beam currents and energy, to study ELF/VLF wave generation and propagation from dc and modulated electron beams, to diagnose beam propagation remotely by studying E region ionization and optical excitation, and to investigate voltage and current distribution in an electrically tethered space vehicle system at higher beam currents.

Reusable Solid Rocket Motor Case: Optimum Probabilistic Fracture Control

A methodology for the reliability analysis of a reusable solid rocket motor case is discussed in this paper. The analysis is based on probabilistic fracture mechanics and probability distribution for initial flaw sizes. The developed reliability analysis can be used to select the structural design variables of the solid rocket motor case on the basis of minimum expected cost and specified reliability bounds during the projected design life of the case. Effects on failure prevention plans such as nondestructive inspection and the material erosion between missions can also be considered in the developed procedure for selection of design variables. The reliability-based procedure that has been discussed in this paper can easily be modified to consider other similar structures of reusable space vehicle systems with different fracture control plans.

Development of On-board Space Computer Systems

This paper describes the functions, characteristics, requirements, and design approaches of the on-board computers for seven space vehicles—Saturn I, Orbiting Astronomical Observatory, Gemini, Saturn IB, Saturn V, Skylab, and Space Shuttle. The data contained in this paper represent an encapsulation of sixteen years of space-borne-computer development. In addition, the evolution of computer characteristics such as size, weight, power consumption, computing speed, memory capacity, technology, architectural features, software, and fault-tolerant capabilities, is summarized and analyzed to point out the design trends and the motivating causes. The evolution in utilization of the on-board computers; their interface with sensors, displays, and controls; and their interaction with operators are summarized and analyzed to show the increasing role played by computers in the overall space-vehicle system.

Measurements of sonic-boom overpressures from Apollo space vehicles

This paper presents representative results of sonic-boom overpressure data recorded during the launch and reentry of the Apollo 15 and 16 space vehicle systems. Comparisons are made between measured overpressures and those predicted using available theory. The measurements were obtained along the vehicle ground track at 68, 87, 92, 129, and 970 km downrange from the launch site during ascent, and at 9, 13, 55, 185, and 500 km from the splash-down point during reentry. Also included are tracings of the sonic-boom signatures along with a brief description of the launch and recovery test areas in which the measurements were obtained, the sonic-boom instrumentation deployment, flight profiles and operating conditions, and high-altitude weather information for the general measurement areas.

Recording Effects of Rain Erosion with High Speed Photographic Techniques

Although controlled rain erosion testing is one of many types of captive dynamic testing that is carried out for missile and space vehicle systems at the Holloman High Speed Track, it is unique in that the photographic recording of this artificial rain and its effects offer unusual problems not encountered in ordinary sled testing. The 6,000 foot rain test section normally used produces an artificial rain with a mean drop diameter of 1.5mm, and has controllable rain drop concentration outputs plus special nozzles and tanks for isolated rain simulations. Sleds traveling at speeds up to Mach 5.5 have carried various test items through this environment so that scientists can study the effects of the rain on test items at various stations along the sled path as well as the total erosion effects after the vehicles are recovered. Detailed photographs of the test object while in the environment are best recorded by synchroballistic techniques. By sampling at intervals along the path, progressive deterioration can be recorded with space-time correlations as the test item passes through the rain field. Aerodynamic characteristics are recorded using photographic shadowgraph techniques. Engineering and general surveillance data is provided by high speed cameras and various lighting techniques.

A Survey of Electronic Attitude Measurement Systems

Introducing rectangular coordinates for the reference coordinate system and the space-vehicle fixed-coordinate system, it will be shown that the transformation matrixes between both coordinate systems which describe the attitude of the space vehicle can be easily computed as functions of the rectangular coordinates of two precise directions known in both coordinate systems. In detail, an electronic attitude measurement will be described based on two precise propagation directions of RF waves. In order to measure the propagation direction in the space-vehicle fixed-coordinate system, a very general interferometer is described. This interferometer is characterized by the fact that the antennas of the interferometer are arbitrarily distributed on the surface of the space vehicle and that the electronic computation of the coordinates of the propagation direction of an RF wave is extremely simple. The design and some modifications of this system are discussed

Asynchronous finite-state machines - A novel control system class.

Asynchronous finite state sequential nonlinear controller synthesis with few flip-flops for dynamic space vehicle systems

Magnetohydrodynamic power generation—a status report

The author gives the historic and theoretical background to the development of m.h.d. power generation and surveys promising recent applications such as topping devices and space-vehicle power systems.

Space vehicle environment and some NASA facilities for their simulation: J.E. Duberg, Environ. Quart., 9(2), 16–22

Environmental problems for space-vehicle systems, such as dynamic response during the launch phase, meteoroid impact, space radiation, and atmospheric reentry heating

Ballistic Missile and Space Vehicle Systems

By Howard S. Seifert and Kenneth Brown London: John Wiley and Sons Ltd. 1962. Pp. xii + 526. Price 96s.