Passive Stabilization System Research Articles

The value of the posterior ligamentous complex in traumatic injury of thoracolumbar junction. Part 1. Morphology and biomechanics

According to modern concepts, one of the basic criteria for the stability of the spinal motion segment in case of its traumatic damage is the integrity of the posterior ligamentous complex (PLC). Regarding the thoracolumbar junction (TLJ) as a zone that is most vulnerable to traumatic injuries, the Thoracolumbar Injury Classification and Severity Score and the clinically oriented AO Spine Thoracolumbar Spine Injury Classification System are used in determining therapeutic approaches in which the state of the thoracic spine is one of three key parameters. The term PLC was first proposed in 1963 by F.W. Holdsworth. However, only the widespread introduction of magnetic resonance imaging into clinical practice made it possible to fully reveal the informativeness of the specified parameter. The complex includes the interspinous, supraspinous ligaments, ligamentum flavum and facet joint capsule. The purpose of the review is to organize modern ideas about the morphology, biomechanical features, clinical significance, and diagnostic possibilities of detecting damage to the PLC in traumatic injuries of the TLJ area. In the first part, the morphological and biomechanical features of the PLC of the TLJ zone are considered in detail. When describing the morphology of some ligaments, the main attention is paid to their length, fixation zones, and certain layers, if such are distinguished. In addition, the relative anatomical location of the considered structures was taken into account. Histological features are indicated only in terms of their biomechanical significance. The analysis of literature data made it possible to organize the data characterizing the biomechanical parameters of each ligament of the PLC for each spinal motion segment of the area under consideration. Stiffness indicators, breaking force, fracture energy, strength and deformation limits, maximum deformation and elastic modulus were taken into account. The features of the load-deformation curve of the TLJ ligaments and methods of calculating the nonlinear change in the stiffness of each ligament of the PLC within the limits of physiological loads are considered. The phenomenon of preload and its clinical significance are described. Some aspects of the interaction between the elements of the passive stabilization system under different load patterns are considered. The data presented in the first part of the review can be useful for a general understanding of the principles of biomechanics of the spinal motion segment and may be used in the construction of highly detailed computer models.

A Novel Ultra-Low Power Consumption Electromagnetic Actuator Based on Potential Magnetic Energy: Theoretical and Finite Element Analysis

A novel concept of a rotary electromagnetic actuator for positioning with ultra-low power consumption is presented. The device is based on harnessing potential magnetic energy stored between permanent magnets facing each other with opposing magnetization polarities. When combined with an active electromagnetic control and passive stabilization system, the rotor of the device can switch between stable equilibrium positions in a fast way with a minimal fraction of the power and energy consumption of a traditional electromagnetic actuator. In this paper, a theoretical model, supported by finite element analysis results, is presented. The actuator has been designed in detail to operate as an optical filter wheel actuator. Calculations demonstrate that the device has the potential to provide a power-consumption saving of up to 86.6% and an energy consumption reduction of up to 58.6% with respect to a traditional filter wheel actuator.

Design Parameters Selection for CubeSat Nanosatellite with a Passive Stabilization System

Probabilistic study of angular motion dynamics has been performed for CubeSat nanosatellites with passive stabilization systems, including aerodynamic, aerodynamic-gravitational, gravitational, and gravitational-aerodynamic ones. Analytical functions of the maximum angle values distribution have been obtained for a nanosatellite axes deviation from required directions (orbital velocity vector or a local vertical) for uniform distribution and Rayleigh distribution of component values of the initial angular velocity vector. Formulas have been derived and nomograms have been plotted for selecting the design parameters (geometrical dimensions, static stability margin, moments of inertia) which ensure the required attitude with the specified probability in circular orbits.

Выбор проектных параметров наноспутника формата CubeSat с пассивной системой стабилизации

Выбор проектных параметров наноспутника формата CubeSat с пассивной системой стабилизации

Flexible and wavelength-independent optical transmission for laser pointing stabilization and assembly error compensation.

A flexible light guide was developed for an ITER (International Thermonuclear Experimental Reactor) poloidal polarimeter which is a passive laser beam alignment and stabilization system for free-space propagation of a wide range of wavelengths. The advantages of using a flexible light guide are (1) to compensate the relative movement between the floor of a building and an optical table, (2) to negate assembly error of the optical transmission line, (3) to minimize the time required for assembly of the line and laser position alignment in a radiological environment, and (4) to transmit a wide wavelength range from visible to far-infrared. The authors fabricated a flexible light guide with an inner diameter of 120 mm and with a motion range of 10 cm. Pointing stability of the laser beam passing through the flexible light guide was less than 70 μrad when the support moved ±50 mm. A flexible light guide error of 70 μrad leads to a beam position displacement of 0.98 mm at a beam position steering mirror ITER poloidal polarimeter that is located 14 m from the flexible light guide. The achieved error is stable enough to guide the laser beam to its target in ITER.

CALCULATION OF ROCKET NOSE FAIRING SHELLS AERODYNAMIC CHARACTERISTICS

The aerodynamic characteristics of the detachable elements of transport systems are introduced, they allow to calculate the trajectories of these elements after their separation and determine the size of elements impact areas. Special consideration is given to head fairing shells, containing cylindrical, conical and spherical sections. Head fairing shells have high lift-to-drag ratio and the widest impact areas. Aerodynamics of bodies of such configurations has been insufficiently studied. The paper presents the numerical results of modeling the flow around a typical head fairing shell in free flight. Open source OpenFOAM package is used for numerical simulation. The aerodynamic characteristics at trans- and supersonic velocities are obtained, flow pattern transformation with the change of the angle of attack and Mach number is analyzed. The possibility of OpenFOAM package for aerodynamic calculations of thin shells is shown. The analysis of the obtained results demonstrate that there are many complex shock waves interacting with each other at flow supersonic speeds, at subsonic speeds vast regions of flow separations are observed. The authors identify intervals of angles of attack, where different types of flow structures are realized, both for trans- and supersonic flow speeds. The flow pattern change affects the aerodynamic characteristics, the aerodynamic coefficients significantly change with increase of the angle of attack. There are two trim angles of attack at all examined flow velocities. The results obtained can be used to develop a passive stabilization system for fairing shell that will balance the body at the angle of attack with minimum lift-to-drag ratio and will reduce random deviations.

Passive Hydrostatic Stability Design of a Box-shaped Autonomous Underwater Vehicle

This paper presents a passive hydrostatic stabilization system design for a box-shaped autonomous underwater vehicle. In order to ensure the quality of data collected, underwater inspection mission require a high stability AUV, especially in roll and pitch direction. However, conventional AUV adopt torpedo-shaped body, which has limited passive restoring moment in roll and pitch direction. Therefore, this paper presents design of a box-shaped autonomous underwater vehicle which is highly stable in roll and pitch direction. The passive stability of the designed autonomous underwater vehicle is improved by putting the heavy components at the bottom part of the vehicle whereas light component at the top part of the vehicle. The designed vehicle weights 68.8 kilogram in air with 0.6 kilogram positive buoyant. It has centre of buoyancy exactly above the centre of gravity with 7.39 centimeter metacentric height. By calculation, the vehicle will have 35.68 newton meter restoring moment at 45 degree. By pool test, result shows that the vehicle is able to retain its original vertical axis as vertical without steady state error.

SSAU Project of the Nanosatellite SamSat-QB50 for Monitoring the Earth's Thermosphere Parameters

SamSat-QB50 nanosatellite design was considered. The main subsystems are described. The basic principles of transformation structure from CubeSat 2U to CubeSat 3U are shown. The passive attitude stabilization system based on hysteresis rods and aerodynamic stabilization principle is suggested for satisfaction of the keys QB50 orientation requirements.

A dilution microcryostat cooled by a refrigerator with an impulse tube

A dilution microcryostat is described, which is designed for conducting physical measurements at temperatures down to 0.1 K or lower. A refrigerator with an impulse tube is used to provide its operation. Owing to the use of a passive stabilization system, which is based on helium condensation, the temperature can be maintained at a level of 0.1 K for 5 h at the disabled refrigerator. The microcryostat is used to investigate low-temperature radiation detectors.

Exo-Leg: An Active Single-Leg External Walking Assist Device

Lower extremity weakness is a serious problem afflicting people all over the world. Until recently, the mobility options for people with this condition have been confining and limit the individual’s functionality. Walking assist devices are presently in development to restore hands-free walking to people with lower extremity weakness. These devices provide the necessary support and power to enable the individual to restore normal ambulation. The proposed design of exoleg, a single leg external walking assist device, addresses the demographic of people with lower extremity weakness. The design includes replication of the gait cycle utilizing mechanical links and user control interface with emphasis on safety. The design couples the actuation of the knee and hip through the use of linkages connected to a single motor. The actuation of the hip is controlled by a 4 bars crank-rocker linkage system while the knee is actuated by corresponding linkages (designed in WORKING MODEL 2D, a commercial simulation software) that generates the knee kinematic profile. The angular profiles of the knee and hip actuations are compared with the actual knee and hip angular trajectories. The frame of the device incorporates a passive ankle stabilization system to compensate for the effects of foot drop. The system utilizes feedback from trigger points from pressure sensors on the foot and goniometers at the hip and knee joints to measure the angulations in gait to keep the device in synchronization with natural ambulation. An on-board microprocessor receives the feedback from the trigger points and sends the actuation signal to the motor. A conceptual design of electrostatic actuator motor is also proposed to keep the device light weight and compact.

Lumbar functional instability: a critical appraisal of the literature

The goals of this paper were to define the concept of instability, to describe the way it can be assessed, to report on impairments of the spine stabilization system in patients with low back pain (LBP), to cite the recommended exercises and, lastly, to examine the results of programs based on lumbar stabilization. Patients suffering from lumbar instability appear to belong to a particular subgroup of subjects with LBP. In the literature, several definitions of lumbar instability have been proposed. Radiological instability, for instance, differs from functional instability. Diagnosis remains difficult: the relevance of static and dynamic radiographs appears limited whereas several signs and clinical instability tests have been described in the literature but remain controversial. The functional stability system of the spine consists of three interdependent components: the passive, the active and the neuromuscular subsystems. The benefits of lumbar stabilization programs for LBP patients have been underlined. Lumbar stabilization exercises are aimed at sensorimotor reprogrammation of spine stabilizer muscles intended to improve their motor control skill and delay of response and consequently to compensate for weakness of the passive stabilization system.

A COMPARISON BETWEEN ROBUST AND FUZZY CONTROLLER DESIGN OF A GYRO STABILIZED ELECTROOPTICAL SIGHT SYSTEM

ABSTRACTIn modern fire control systems, Line of Sight (LOS) stabilization plays anessential and crucial part. LOS stabilization systems have a wide range of military andcivilian applications. Their importance arises from the critical applications that employthese systems. Two techniques are used for the LOS stabilization systems, passive andactive. The passive LOS stabilization systems are easy to design and are manufacturedat a relatively low cost to be interfaced with different types of electro optical systems.Hence, it can be used to increase the efficiency of many armored vehicles serving in thearmed forces, where it may be used for constructing fire control systems. The passiveLOS stabilization systems are multi-input multi-output (MIMO) systems that are highlynonlinear and possess a strong coupling effect between their states. It presents achallenging system to control.In this paper the analysis of the passive LOS stabilization system with thedevelopment of its nonlinear mathematical model is derived. Two different types ofcontrol algorithms are presented. The first controller is a Linear Quadratic Gaussiancontroller (LQG). The controller presents a conventional control technique that provesto be stable with high transient and tracking performances. The controller is applied tothe LOS stabilization system and the simulation results are introduced. Next, anintelligent fuzzy controller is introduced. The fuzzy control presents a nonlinear controltechnique that compensates the system's nonlinearity; hence, it is more appropriate tostabilize and control the system under consideration. The fuzzy controller is designed todecouple the relationship between the system state variables. The controller'sperformance is verified through simulations and results. Finally, comparative analysis between the two developed controllers isconducted. It discusses the advantages and disadvantages of each control algorithm.

An Assessment between Classical Fuzzy and Fuzzy Model Reference Learning Controller Design of Electro-Optical pointing and tracking System

ABSTRACTElectro-optical pointing and tracking systems (EOPTS) have a wide range of military andcivilian applications. The passive line of sight (LOS) stabilization systems are multi-inputmulti-output (MIMO) systems that are highly nonlinear and possess a strong coupling effectbetween their states. it presents a challenging systems to control. In this paper the analysis ofthe passive (EOPTS) stabilization system with the development of its nonlinear models isderived. Two different types of control algorithms are presented. The first controller is aclassical fuzzy control. The controller presents a good technique that proves to be stable withhigh transient and tracking performances. The controller is applied to the LOS stabilizationsystem and the simulation results are introduced. Next, A Model Reference Learning fuzzyController less dependant on the designer knowledge of the LOS stabilization system isproposed. Such controller possesses a learning mechanism that is able to form its rule-base bywatching the system behavior. The learning mechanism utilizes a reference model thatdescribes the desired performance. The designed process of the controller and simulationresults of implementing the controller to the system is introduced. Finally, comparativeanalysis between the two developed controllers is conducted. It discusses the advantages anddisadvantages of each controller algorithm.

Design and Development of a Two-Axis Passive Line-of-Sight Stabilization System

The line-of-sight (LOS) stabilization system is basically a system that has the capability of maintaining the sightline—for example, of an optical sensor—fixed in inertial space even when the system is subjected to an external vibrational environment. This paper examines and presents the feasibility of using a passive LOS stabilization system to maintain the sightline stability to within 1 mrad when it is subjected to linear and angular vibrations and other disturbances. Equations of motion of the system as well as the vibrational response equations are presented. From these equations, design parameters that affect the vibrational response of the system are established. A prototype of the LOS stabilization system has been built. The pointing stability of this prototype with different values of the design parameters is evaluated and compared with simulation results. Initial test results on the prototype are encouraging, with pointing stability of less than 1 mrad on both axes, which is within the original design objective.

Impact of the passive stabilization system on the dynamic loads of the ITER first wall/blanket during a plasma disruption event

Impact of the passive stabilization system on the dynamic loads of the ITER first wall/blanket during a plasma disruption event

Impact of the passive stabilization system on the dynamic loads of the ITER first wall/blanket during a plasma disruption event

Abstract In next-generation tokamak devices (i.e. ITER), passive stabilization of the plasma is required to mitigate the consequences of the plasma vertical displacements and to reduce the occurrence of plasma disruptions. With this aim, two main design approaches have been considered. The first one (adopted in the ITER CDA design) consists of copper stabilization loops (twin loops) attached to box-shaped blanket segments which are electrically and mechanically separated along the toroidal direction. In the second design approach (under consideration for the ITER EDA design), relying on a lower plasma elongation, no specific stabilization loops are required and the passive stabilization is achieved by toroidally continuous components, in particular by the plasma facing wall of the blanket segments, electrically connected along the toroidal direction, thus allowing a toroidal current to flow during the electromagnetic transients. In both cases electrodynamic loads arise in the blanket structures during plasma disruptions and/or vertical displacement events. A comparison between the two design approaches has been carried out from the eddy-current and related load distribution viewpoint.

Design and Operation of the Ponce de Leon

A unique ship, and to some extent the transportation system of which it is a part, is described. The ship was designed to carry 250 40-ft highway trailers and about 300 automobiles in the New York to Puerto Rico trade on a weekly schedule. The ship is 700 ft long and 105 ft wide over the main deck. It displaces 24,000 tons at the design draft of 27 ft. A single boiler, steam turbine propulsion plant generates 32,000 shp driving the ship with a single screw. A controlled passive stabilization system based on the U tube tank principle is installed. Terminal facilities at both ends of the run include vehicle marshalling yards, yard tractors, scales, and loading ramps.