Increase In Angular Velocity Research Articles

ОЦЕНКА ПАРАМЕТРОВ КЛОТОИДНОЙ ТРАЕКТОРИИ ВХОДА В ПОВОРОТ КОЛЕСНОЙ МАШИНЫ

A theoretical assessment of the influence of the translational speed of a wheeled vehicle and the angular rotation speed of its steered wheels on the main characteristics of the clotoid curve is carried out. The calculations were carried out with the following initial parameters characterizing the structural and geometric features of the wheeled vehicle: the longitudinal base of the machine is 2.6 m; the distance between the axes of the front axle pins is 1.8 m; the maximum angle of rotation of the driven wheels is 33 °30'. The speed of the translational movement of the machine and the angular rotation speed of the controlled wheels was varied. The results of the evaluation are as follows. With a constant angular rotation speed of the front wheels of 0.195 s-1 and with a change in the speed of translational motion in the range from 0.57 m/s to 1.78 m / s, the maximum abscissa of the clotoid curve increased from 0.113 m to 1.074 m – almost tenfold, and the maximum ordinate from 1.703 m to 5.141 m - approximately three times. At a constant translational speed of 1.41 m/s and with a change in angular velocity in the range from 0.0974 s-1 to 0.292 s-1, which corresponds to the time interval of turning the wheels at a maximum angle from 2 s to 6 s, it was obtained: the maximum abscissa decreases with an increase in angular velocity from 2.585 m to 0.305 m - by 8.5 times, and the maximum ordinate - from 7,689 m to 2.79 m - 2.8 times. The calculation established that the minimum radius of curvature of the trajectory at the end of the section of the entrance to the turn is equal to 5,061 m, which corresponds, as it should be, to the value of the minimum theoretical radius given in the technical characteristics of some wheeled vehicles with the accepted initial parameters.

A Soiling Mitigation Method to Enhance the Performance of ADAS in Precipitation

<div class="section abstract"><div class="htmlview paragraph">The emergence of autonomous driving technology has tremendous mobility and social-economic benefits. Autonomous vehicles (AVs) rely on various sensors for environmental and traffic data. However, the sensor performance and reliability degrade in adverse weather conditions, which poses a challenge to the safety of AVs. Existing active mitigation strategies such as wipers and water jets are active, complex, and expensive to implement. This study investigated soiling mitigation via a passively rotating lens with the goal to maintain Advanced-Driver-Assistance-System (ADAS) sensor visibility in the rain. The concept of rotating lens has merely been lightly explored in the literature but never studied in detail with realistic continuous rain simulation to verify soiling mitigation effectiveness. An optical camera in place of a frontal vehicle ADAS sensor was integrated into a rotating lens for visual characterization. A wind tunnel was used to simulate various wind-driven rain scenarios in both urban and suburban driving speeds. As driving speed in rain increases, sensor reliability and performance exacerbate due to an increase in perceived rain characteristics, including angle and intensity. This investigation studied the correlation of the rotating lens angular velocity at different driving speeds and its effectiveness in mitigating soiling under various perceived rain conditions. The increase in angular velocity resulted in a direct increase in centrifugal force experienced by each raindrop present on the lens; hence, providing a mitigation effect when droplets are spun off. Compared to stationary reference lens, observations from mitigation-enabling rotating lens showed greatly improved clarity from the optical camera frontal view in reduction of environment obstruction and distortion from rain droplets. Image processing results suggested high confidence in combating all droplet sizes and driving-in-rain conditions. This investigation successfully demonstrated the effectiveness of rotating lens as a concept for soiling mitigation and provided insight for enhancing ADAS sensor performance and reliability in adverse weather conditions.</div></div>

Single-Leg Drop Jump Biomechanics After Ankle or Knee Joint Cooling in Healthy Young Adults.

It is unclear if lower-extremity joint cooling alters biomechanics during a functional movement. To investigate the effects of unilateral lower-extremity cryotherapy on movement alterations during a single-leg drop jump. A crossover design. Laboratory. Twenty healthy subjects (10 males and 10 females; 23y, 169cm, 66kg). Subjects completed a single-leg drop jump before and after a 20-minute ankle or knee joint cooling on the right leg, or control (seated without cooling) on 3 separate days. Time to peak knee flexion, vertical ground reaction force, lower-extremity joint angular velocity (sagittal plane only), and angle and moment (sagittal and frontal planes) in the involved leg over the entire ground contact (GC; from initial contact to jump-off) during the first landing. Time to peak knee flexion was compared using an analysis of variance; the rest of the outcome measures were analyzed using functional analyses of variance (P < .05). Neither joint cooling condition changed the time to peak knee flexion (F2,95 = 0.73, P = .49). Ankle joint cooling reduced vertical ground reaction force (55N at 4% of GC), knee joint angular velocity (44°/s during 5%-9% of GC), and knee varus moment (181N·m during 18%-20% of GC). Knee joint cooling resulted in a reduction in knee joint angular velocity (24°/s during 37%-40% of GC) and hip adduction moment (151N·m during 46%-48% of GC), and an increase in hip joint angular velocity (16°/s during 49%-53% of GC) and plantarflexion angle (1.5° during 11%-29% of GC). Resuming activity immediately after lower-extremity joint cooling does not seem to predispose an individual to injury during landing because altered mechanics are neither overlapping with the injury time period nor of sufficient magnitude to lead to an injury.

Can We Modify Maximal Speed Running Posture? Implications for Performance and Hamstring Injury Management.

Sprint kinematics have been linked to hamstring injury and performance. This study aimed to examine if a specific 6-week multimodal intervention, combining lumbopelvic control and unning technique exercises, induced changes in pelvis and lower-limb kinematics at maximal speed and improved sprint performance. Healthy amateur athletes were assigned to a control or intervention group (IG). A sprint test with 3-dimensional kinematic measurements was performed before (PRE) and after (POST) 6 weeks of training. The IG program included 3 weekly sessions integrating coaching, strength and conditioning, and physical therapy approaches (eg,manual therapy, mobility, lumbopelvic control, strength and sprint "front-side mechanics"-oriented drills). Analyses of variance showed no between-group differences at PRE. At POST, intragroup analyses showed PRE-POST differences for the pelvic (sagittal and frontal planes) and thigh kinematics and improved sprint performance (split times) for the IG only. Specifically, IG showed (1)a lower anterior pelvic tilt during the late swing phase, (2)greater pelvic obliquity on the free-leg side during the early swing phase, (3)higher vertical position of the front-leg knee, (4)an increase in thigh angular velocity and thigh retraction velocity, (5)lower between-knees distance at initial contact, and (6)a shorter ground contact duration. The intergroup analysis revealed disparate effects (possibly to very likely) in the most relevant variables investigated. The 6-week multimodal training program induced clear pelvic and lower-limb kinematic changes during maximal speed sprinting. These alterations may collectively be associated with reduced risk of muscle strain and were concomitant with significant sprint performance improvement.

Locomotion and searching behaviour in the honey bee larva depend on nursing interaction

Although honey bee brood does not need to seek shelter or food and restricts its movements to small wax cells, larvae have some degree of motility. Previously, other studies described how honey bee larvae showed analogous behaviours to the wandering period in holometabolous insects. The current research aimed to measure locomotion of the honey bee brood at different conditions of food supply and larval stadia. Besides, we developed an actometry assay to describe the larval behaviour under laboratory conditions. Our results suggested that the satiety and developmental program of larvae modulated their locomotion. Before they pupated, larval speed increased sharply and then it dropped until quiescence. However, starvation also induced an increase in angular velocity of brood. Starved larvae were between three and five times faster than the satiated ones. Moreover, fifth instars left their wax cells after 2 h of starvation without nurse bees. In the actometry assay, larvae showed behaviours of dispersion and changes in their kinematic parameters after detecting a tactile stimulus like the edge of arenas.

Dynamic Analysis of the Complex Motion of Three-Section Cudgel in Wushu Sports

Purpose: To provide some suggestions on how to effectively master these movements during training. Methods: The dynamics method and ABAQUS simulation analysis were used to analyze the two technical movements of the three-section cudgels: wrestling cudgels and retrieving cudgels. Results: In the process of wrestling the cudgel, the best effect is achieved when the height of the cudgel holding hand is between 70 cm and 80 cm from the ground. The maximum height of the rebound was very similar with different initial angular velocities, at 4.5–9 cm. The initial angular velocities caused significant impact to the horizontal movement of cudgel at 8 s. By excluding the errors, the horizontal movement of cudgel increased approximately linearly with the increase of the initial angular velocity. Conclusions: When the height between held cudgel and the ground was controlled at 1.5 times the height of the middle section, the rebound of the tail section was the least. When completing the movement of three-section cudgel, the cudgel body should be in the same plane perpendicular to the ground and to better retrieve the three-section cudgel. The main factor affecting the cudgel wrestling was the height between the cudgel holder and the ground.

Steady circular hydraulic jump on a rotating disk

The paper deals with the steady axially symmetric flow of a viscous liquid layer over a rotating disk. The liquid is fed near the axis of rotation and spreads due to inertia and the centrifugal force. The viscous shallow-water approach gives a system of ordinary differential equations governing the flow. We consider inertia, gravity, centrifugal and Coriolis forces and estimate the effect of surface tension. We found four qualitatively different flow regimes. Transition through these regimes shows the continuous evolution of the flow structure from a hydraulic jump on a static disk to a monotonic thickness decrease on a fast rotating one. We show that, in the absence of surface tension, the intensity of the jump gradually vanishes at a finite distance from the axis of rotation while the angular velocity increases. The surface tension decreases the jump radius and destroys the steady solution for a certain range of parameters.

Microstructural Design of Ba0.5La0.5Co0.5Fe0.5O3 Perovskite Ceramics.

Ba0.5La0.5Co0.5Fe0.5O3−δ was synthesized in the solid-state reaction route. The influence of ball milling parameters (such as milling media size, angular velocity, and time), pelletizing pressure, and annealing parameters on the microstructure was studied. The grain size distribution and density or specific surface area changes were investigated in each approach while the individual parameters were changed. The evaluation of BLCF synthesis parameters enables tailoring the microstructure to various applications. It was observed that with lowering the size of milling balls and increasing the angular velocity the material will be porous and thus more appropriate as electrode material in proton ceramic fuel cell or electrolyzer. An increase of time, balls diameter, and/or angular velocity of milling enables one to densify the material in case of membrane application in, e.g., as a gas sensor. The significant influence on densification has also annealing temperature increase. Applying 1200 °C during annealing leads to dense material, while at 1100 °C shows visible porosity of the product. In this work, we present the results of the BLCF synthesis parameters change allowing the selection of appropriate parameter values depending on the further application as PCCs.

РУХ ЧАСТИНКИ ПО СФЕРИЧНОМУ СЕГМЕНТУ З ВЕРТИКАЛЬНИМИ РАДІАЛЬНО ВСТАНОВЛЕНИМИ ЛОПАТКАМИ

The relative motion of a particle on the inner surface of a horizontal spherical disk along a vertical blade mounted in the radial direction is considered in the article. The disk rotates around a vertical axis with a given angular velocity. A system of differential equations of motion of a particle is compiled and solved by numerical methods. The kinematic characteristics of the motion are found, the regularities of the relative motion of the particle on the surface of the cylinder are clarified. Graphs characterizing the motion of a particle at certain given parameters are constructed, namely: graph of angle change, which sets the position of the particle on the surface of the sphere in the direction of the meridian, graphs of absolute and relative velocities, graphs of change of forces of the reaction of the spherical disk and blade. Numerical integration of the obtained differential equation showed that in half a second the particle rises to the height of the hemisphere, and then begins to fall. In this case, the descent alternates with the rise to a complete stop of the particle at a certain height, i.e. the particle “sticks” and then rotates with the hemisphere. The angle of “sticking” can be found analytically. In addition, numerical calculation methods have shown that at zero value of the friction coefficient of the particle on the disk surface, i.e. at its absolutely smooth surface, and at the non-zero value of the friction coefficient of the blade surface, and at an unlimited increase of the disk angular velocity the particle “sticks” at the height of the center of the sphere. If both surfaces are absolutely smooth, then the damping oscillations of the angle that determines the position of the particle on the surface of the sphere in the direction of the meridian, occur indefinitely. The working surface of the disk of the centrifugal apparatus, which is made in the form of a spherical segment, provides the beginning of the flight of the particle at the time of ascent from the disk at a given angle to the horizontal plane, increasing the scattering area of the technological material. The analytical description of the particle motion obtained in the article makes it possible to investigate its acceleration along with the blades of the disk and to find the relative and absolute velocities at the moment of particle ascent from the disk. The found analytical dependencies allow determining the influence of constructive and technological parameters on the process of particle acceleration.

Thermodynamics of heavy quarkonium in rotating matter from holography

Using the guage/gravity correspondence, we study the free energy, entropy, binding energy, and internal energy of a heavy quarkonium in the rotating quark-gluon plasma (QGP). First, we extend the static black hole with planar horizon to the spinning case, which is dual to the rotating matter. Subsequently, we use the Wilson loop to get the free energy of heavy quarkonium. Entropy, binding energy, and internal energy are naturally given by the thermodynamic relationship. It is found that angular velocity will suppress the dissociation temperature of heavy quarkonium and change the system from confined to deconfined phase with the increase of angular velocity. Thus, the heavy quarkonium will dissolve at a certain separating distance in the deconfined phase. We also compare these thermodynamic quantities of the quark-antiquark pair in the direction parallel and transverse to the rotation direction. At last, the free energy, entropy, and internal energy of a single quark are discussed. It is found that these quantities are decreasing functions of temperature.

Numerical analysis of the flow mechanism and axial force characteristics of the cavity in a centrifugal pump with a front inducer

At three flow conditions (0.8Qd, 1.0Qd, and 1.2Qd), the centrifugal pump cavity with front inducer was expanded at 0°, 90°, 180°, and 270°, and a flow path analysis of the axial cross section at the four angles was performed. This revealed that the circumferential and radial velocities of the liquid in the pump cavity along the same angle at different radii follow an axial and radial variation law to different degrees. The pump cavity center axial liquid velocity component along the radial distribution at different angles was analyzed, and liquid pressure in the pump cavity along the radial distribution was numerically analyzed from different points of view. The mean pump cavity pressure was plotted along the radial distribution curve, and a detailed numerical calculation of the axial force of the centrifugal pump and pump cavity was developed. The influence of flow conditions on the liquid flow mechanism and axial force characteristics in the pump cavity was thoroughly discussed. The results showed that liquid flow in the centrifugal pump cavity with the front inducer is mainly restricted by the main flow of the volute. The liquid eddy current in the pump cavity is mainly concentrated near the volute and the hub at 90° and 180° angles, and the higher the flow rate, the larger is the area of the side vortex of the impeller-cover plate, and the smaller is the area of the side vortex of the pump-cover plate. When the flow rate increases, the flow direction of the eddy current at the same angle in the pump cavity remains unchanged, but when the flow rate becomes too high, the flow direction of the eddy current at the same angle in the pump cavity changes. When the range of circumferential and radial partial velocities decreases, the rotational angular velocity increases, and the pressure decreases. At low flow rate, the larger the area of the volute corresponding to the pump cavity, the higher the speed becomes. The axial force in the pump cavity is the most important factor determining the axial force of the centrifugal pump.

무릎 스트랩과 테이핑 적용이 배구선수의 외발 착지에서 슬개건 통증과 하지 동역학 및 운동학에 미치는 영향

The primary purpose of this study was to compare patellar tendon pain and low extremity kinetics and kinematics of male high school volleyball players on one-leg landing after applying a strap, C-tape, and E-tape, respectively. A total of 16 male high school volleyball players who had no history of lower extremity injury at least for 3 months were recruited(age: 16.37±1.08years, height: 185.56±5.52cm, weight: 76.81±8.52kg). Each participant were alternately equipped with a strap, C-tape, or E-tape on each patellar tendon, and visual analogue scale(VAS) was measures during one leg landing. Maximal knee flexion angle, range of motion, angular velocity, moment, and maximal ground reaction force at the hip, knee, and ankle joint were assessed after each application using 3 dimensional motion analyses. Statistical analyses were done with one-way repeated measure ANOVA and post-hoc analysis. The VAS of strap(2.56±1.45) and C-tape(2.87±1.31) were lower than that of E-tape(3.50±1.31; each p.001 and p=.007). The mean angular velocity of the knee flexion (285.77±88.60deg/s) was significantly higher in strap than in E-tape(242.68±61.64deg/s; p=.026). In summary, it appeared that the application of strap or C-tape was related to effectively reducing patellar tendon pain. Additionally, it could be postulated that the application of a strap attributed to the increase of knee flexion angular velocity during one-leg landing.

Dynamic analysis of rotating double‐tapered cantilever Timoshenko nano‐beam using the nonlocal strain gradient theory

Based on the nonlocal strain gradient theory, the coupling nonlinear dynamic equations of a rotating double‐tapered cantilever Timoshenko nano‐beam are derived using the Hamilton principle. The equation of motion is discretized via the differential quadrature method. The effects of the angular velocity, nonlocal parameter, slenderness ratio, cross‐section parameter, and taper ratios are examined and discussed. It is shown that taper ratios and cross‐section parameter play a significant role in the vibration response of a rotating cantilever nano‐beam. Further as rotational angular velocity increases, the taper ratios and cross‐section parameter effect on the frequency response are increased for first modes of vibration.

МАТЕМАТИЧНА МОДЕЛЬ СИСТЕМИ ОРІЄНТАЦІЇ РОТОРА ВІТРОУСТАНОВКИ ЗА РАХУНОК ВЛАСНОЇ ПАРУСНОСТІ РОТОРА

Незважаючи на значний досвід в проектуванні вітроустановок малої потужності в процесі їх експлуатації виникають руйнування окремих елементів установки, які можуть призвести до руйнування установки в цілому. Одним з важливих чинників, що призводить до руйнування елементів, зокрема лопатей, є гіроскопічні навантаження, що виникають в них при орієнтації ротора за напрямком повітряного потоку. При цьому необхідно зауважити, що перед конструкторами стоїть певна дилема. З однієї сторони збільшення кутової швидкості призводить до зменшення енергетичних втрат при орієнтації ротора, а з іншої – до збільшення гіроскопічних навантажень в лопаті.&#x0D; На сьогоднішній день в ряді робіт запропоновані математичні моделі систем орієнтації ротора за напрямком повітряного потоку за рахунок флюгерної площини хвоста. При цьому використовуються різноманітні конструктивні схеми даної системи орієнтації ротора, такі як підпружинений хвіст, хвіст на косому шарнірі та інші. Система орієнтації ротора за рахунок власної парусності ротора практично недосліджена і потребує теоретичних розробок та подальшої їх експериментальної перевірки.&#x0D; В даній роботі пропонується розробити математичну модель системи орієнтації ротора вітроустановки за рахунок власної парусності ротора із врахуванням ряду параметрів та характеристик даної системи орієнтації. Запропонована математична модель орієнтації ротора дозволило отримати рівняння для розрахунку кутових швидкостей орієнтації ротора в залежності від швидкостей вітру, кута відхилення ротора від напрямку повітряного потоку та ряду конструктивних параметрів системи орієнтації ротора. Отримані кутові швидкості орієнтації ротора дозволяють визначити енергетичні втрати та гіроскопічні навантаження на елементи конструкції вітроустановки в процесі орієнтації ротора. Дані рівняння також дозволяють визначити параметри, якими можна впливати на величину кутової швидкості орієнтації ротора, такі як відстань від вісі обертання гондоли до площини ротора та коефіцієнт демпфування відповідних пристроїв, що дозволяє вибрати раціональну величину кутової швидкості орієнтації ротора з урахуванням можливих втрат виробітку вітроустановкою та величин гіроскопічних навантажень в лопатях і елементах гондоли. Бібл. 9, рис. 1.

Nonlinear Convection in Micropolar Fluid Flow Past a Non-Isothermal Exponentially Permeable Stretching Sheet in Presence of Heat Source/Sink

This paper aims to present the consequences of nonlinear convection on boundary layer flow of micropolar fluid over a non-isothermal exponentially stretching sheet. The influences of suction/blowing and heat source/sink are also considered. Using similarity transformations the governing partial differential equations are reduced to ordinary differential equations and these nonlinear equations are then solved numerically by converting the boundary value problem to an initial value problem with the help of shooting technique and Runge-Kutta method. The results are discussed through graphical representations providing physical interpretations as far as practicable. It is found that both fluid velocity and angular velocity increase with the rise in material parameter but the temperature decreases in this case. Fluid velocity increases but the angular velocity and temperature both decrease with the rise in mixed convection parameter and also with the nonlinear convection parameter.

BIOMECHANICAL STUDY OF MUSCLE MOVEMENT IN THE PROCESS OF FOOTBALL TECHNICAL TRAINING

Study of biomechanical characteristics of muscles can provide an effective reference for the training of athletes. Football is a vigorous sport, and physical collision and damage are frequent during competition and training. In order to improve football skills and prevent sports injuries, 10 athletes from Sport College of Shaoyang University, Hunan, China, were tested for isokinetic muscle strength. The moment of flexors and extensors was measured when the flexion and extension angular speed of hip and knee joints was 50∘, 100∘, 150∘, 200∘, 250∘, 300∘, 350∘ and 400∘, respectively. Moreover the characteristics of force moment of flexor and extensor were verified by testing the electromyographic signal of the flexor and extensor of the hip and knee joints with isokinetic concentric exercise using piezoelectric sensor. The results showed that the electromyographic signal of the flexor and extensor of the hip and knee joint decreased with the increase of angular velocity of isokinetic concentric exercise; the electromyographic signal obtained by the piezoelectric sensor verified the law that the output of the flexor and extensor decreased, the extensor of the hip joint had incoordination during rapid movement, and the output of the extensor was always larger than that of the flexor no matter how fast the extensor moved.

Numerical simulation of the operation of the disc shredder

The purpose of the work is to model the performance of the disk grain shredder by numerical methods of determining the performance of the device and its components, and to establish the existing trends in the influence of the size of the initial particles on the components of the shredder performance. The increase in the initial particle size leads to an increase in the initial angular velocity of the particle movement, which increases as the particle is compressed, while the increase in particle size does not significantly reduce the productivity of the shredder due to the worsening conditions of particle capture by the disks as they increase in size. The increase in the initial spring compression force ensures a reduction in the thickness of the resulting flattened particles and at the same time reduces the productivity.

The effects of annealing temperature and angular velocity variation on microstructure and optical properties of barium titanate (BaTiO3) using chemical solution deposition method

This study is aimed to find out the energy gap value of BaTiO3 thin film since this study has a purpose to reduce the energy gap so that it can be used for photovoltaic applications. The making of Barium Titanate (BaTiO3) thin film was carried out on the quartz substrate using the Chemical Solution Deposition (CSD) method with the technique of depositing spin coating. The making of BaTiO3 thin film was carried out using variation of angular velocity at 4000 rpm and 5000 rpm and variation of annealing temperature at 750°C, 800°C, 850°C. The samples in this study were annealed at 750°C, 800°C, 850°C with a holding time of 1 hour and an increase in temperature of 3°C/minute. The microstructure characterization of the samples was carried out using X-Ray Diffraction (XRD) equipment, and the thickness of the thin film characterization and grain size of samples using Scanning Electron Microscopy (SEM) equipment. The annealing temperature increase, the intensity becomes higher. As the annealing temperature increase, then the crystallinity, crystallite size and grain size of BaTiO3 thin film will get bigger. The annealing temperature increase is resulted the thickness and energy gap are smaller. The intensity value of the XRD remains decrease along with the angular velocity increase. The higher angular velocity causes the crystallinity and crystallite size of BaTiO3 thin film becomes higher. However, the angular velocity increase then the grain size will become smaller. The angular velocity higher, then the BaTiO3 thin film gets thinner. The angular velocity gets higher, then the smaller energy gap produced. The energy gap value was produced between 3.00 – 3.50 eV.

Wave propagation analysis of a spinning porous graphene nanoplatelet-reinforced nanoshell

In this article, wave propagation behavior of a size-dependent spinning graphene nanoplatelet-reinforced composite (GNPRC) cylindrical nanoshell with porosity is presented. The effects of small scale are analyzed based on nonlocal strain gradient theory (NSGT), this accurate theory employs exact length scale parameter and nonlocal constant. The governing equations of GNPRC cylindrical nanoshell coupled with piezoelectric actuator (PIAC) are evolved by minimum potential energy principle and solved by the analytical method. For the first time in the current study, wave propagation-porosity behavior of a GNPRC cylindrical nanoshell coupled with PIAC is examined based on NSGT. The results show that, as the angular velocity increases, the difference between the minimum and maximum values of the phase velocity decreases. Another important result of this paper is that, by increasing the radius, extremum values of phase velocity occur in the lower values of the wave number. Finally, the influences of porosity, angular velocity, wave number and different graphene platelet distribution patterns on the phase velocity are investigated using the mentioned continuum mechanics theory. The outputs of the present work can be used in structural health monitoring and ultrasonic inspection techniques.

Control failure of the roll-isolated inertial navigation system under large pitch angle

Roll-isolation is an effective way for spinning vehicle to greatly reduce the roll gyro range of strapdown Inertial Navigation System (SINS) and increase the accuracy of inertial navigation. However, during a recent flight test, the roll-isolated control system failure was observed under a large pitch angle (70°⩽θ⩽85°), which introduces a sharply increase in the roll angular velocity, the saturation of roll gyro and the inertial navigation failure. To address this issue, the governing equation of the roll-isolated system is derived with the consideration of various disturbance factors. The control failure is reproduced by numerical simulation. And the results show that the pitch and yaw angular velocity can cause a dramatic increase in roll rate under the large pitch angle, resulting in the roll-isolated control failure. Meanwhile, an improved roll-isolated control system is developed using PI controller, which is verified by mathematical simulation.