Roll Axis Research Articles

ОБРАБОТКА ОТВЕРСТИЯ ОПОРНОГО РОЛИКА ХОДОВОЙ СИСТЕМЫ ТРАКТОРА ПРОШИВКОЙ

Restoring the surface of the roller treadmill to its nominal value using automatic surfacing technology makes it possible to obtain a significant surfacing layer with a sufficient degree of strength and wear resistance. At the same time, as a result of thermal action, the metal of the roller receives a linear shrinkage, due to which the diameter of the hole for the bearing of the roller axis decreases. In this case, it becomes impossible to install the outer bearing cage. (Research purpose) The research purpose is substantiating the method of processing the seat under the outer bearing cage after surfacing the treadmills of the support roller. (Materials and methods) It was noted that the surfaces of the treadmills of the support rollers wear out quickly as a result of abrasive friction with the track link and the soil. It was clarified that when surfacing in all ways, metal shrinkage occurs and the diameter of the hole for the outer bearing cage decreases. (Results and discussion) It was found that the wear of the treadmills of the support rollers averaged 13.9 millimeters. Restoration of the treadmill surface of the roller to the nominal value, carried out by the method of multilayer automatic surfacing, caused a decrease in the diameter of the roller opening by an average of 0.73 millimeters. We chose from the considered options for calibrating the hole the most preferable from and time-saving one, the firmware processing method. (Conclusions) The appearance of shrinkage of the support roller hole during restoration by automatic surfacing and the method of calibrating the hole using firmware were substantiated. The method provides tension in the coupling of the outer ring of the bearing with the roller within 0.015-0.039 millimeters and surface cleanliness within Ra 1.25-0.63 micrometers. The firmware is simple in design and can be manufactured in a repair shop.

A multi-objective optimization workflow of ring-rolling process parameters based on production energy and time

Our industrial era is characterized by a significant attention to environmental aspects and production sustainability. Under this point of view, the minimization of the process energy represents a milestone leading to a consistent reduction of pollution. However, to promptly react to the high production rate market request, companies employ time saving manufacturing strategies, often in contrast with this principle. Considering this, an optimization concerning the reduction of both production time and energy, results to be strategical, especially when energy-intensive processes, such as ring rolling, are considered. Ring rolling is a shaping process performed by a dedicated equipment, composed of a driving roll, an idle roll, and a couple of axial rolls, allowing to obtain seamless rings while simultaneously reducing their height and thickness, while enlarging diameter. The kinematics of each component of the equipment can be set independently. This leads to several process conditions influencing quality, energy, and times, and makes it difficult the selection of the most suitable configuration. In this paper, a multi-objective optimization workflow is presented. Starting from validated FEM simulation campaign results, the proposed methodology allowed to individuate the best process parameters combination for limiting energy and time, encouraging its application to a wider range of energy-consuming processes.

Control moment coefficient methodology validation for eVTOL sizing

This paper presents a novel approach for the preliminary design of electric Vertical Takeoff and Landing (eVTOL) aircraft that utilizes the new Control Moment Coefficient (CMC) to size electric motors and to determine the rotor location and incidence angle. The CMC is determined for both thrust and arm length in eVTOL aircraft design, and is used to measure the moment produced by the rotors in the roll, pitch, and yaw axes. Analyzing its dimensionless value thus allows insights into an eVTOL aircraft's controllability. To test our methodology, two eVTOL aircraft were used in flight tests, one of which had up to 126% higher CMC values than the other. The results of the flight tests showed that a higher CMC value yielded many benefits, including an increased margin of safety between the rotors and the saturation level, reduced tracking error, and reduced control effort (or energy consumption).Furthermore, the 126% increase in the dimensionless CMC related to the pitch resulted in a 30% increase in the Pulse-Width Modulation - PWM margin of safety of the rotors at the saturated level while still maintaining a reasonable tracking error and a 97% decrease in the pitch control effort. Our research suggests that incorporating higher CMCs into the preliminary design of an eVTOL aircraft can significantly improve its safety and controllability. We hope that our findings will encourage further exploration of this promising approach in future.

Estimation of Axis Roll Pitch of GY-91 IMU Sensor Reading Using Kalman Filter

The Inertial Measurement Unit (IMU) sensor is a tool used to measure the speed and acceleration of an object in 3 dimensions (x, y, z). IMU sensors are often used in robotics, drone control, autonomous vehicles, and augmented reality applications. Usually, the data obtained from the IMU sensor is contaminated by interference and noise, which can reduce measurement accuracy. Kalman Filter is a statistical method used to combine measurement data with a mathematical system model to produce better estimates. In the IMU context, the Kalman Filter removed interference and noise affecting acceleration and speed data so that IMU sensor data could be estimated more accurately. This algorithm predicts the next data state based on previous data and updates the prediction with new measurement data. The measurement implementation in this research is the IMU sensor on the GY-91 module to determine the object's tilt on the pitch, roll, and yaw axes during flight. The ARM STM32F407VGT6 microcontroller pin reads the sensor, and then the estimation and prediction process is carried out using the Kalman filter algorithm. With the parameters Kalman Measurement Error = 1, Estimation Error = 0.12, and Covariance Process = 0.4, it can predict the reading results from the IMU sensor well.

Neuro-fuzzy system based proportional derivative gain optimized attitude control of CubeSat under LEO perturbations

Prompt attitude stabilization is more challenging in Nano CubeSat due to its minimal capacity, weight, energy, and volume-constrained architecture. Fixed gain non-adaptive classical proportional integral derivative control methodology is ineffective to provide optimal attitude stability in low earth orbit under significant environmental disturbances. Therefore, an artificial neural network with fuzzy inference design is developed in a simulation environment to control the angular velocity and quaternions of a CubeSat by autonomous gain tuning of the proportional-derivative controller according to space perturbations. It elucidates the dynamics and kinematics of the CubeSat attitude model with reaction wheels and low earth orbit disruptions, i.e., gravity gradient torque, atmospheric torque, solar radiation torque, and residual magnetic torque. The effectiveness of the proposed ANFIS-PD control scheme shows that the CubeSat retained the three-axis attitude controllability based on initial quaternions, the moment of inertia, Euler angle error, attitude angular rate, angular velocity rate as compared to PID, ANN, and RNN methodologies. Outcomes from the simulation indicated that the proposed controller scheme achieved minimum root mean square errors that lead towards rapid stability in roll, pitch, and yaw axis respectively within 20 s of simulation time.

Investigation of the misalignment and modification for crown roller contacts under mixed lubrication

A new contact model of finite-length crowned roller bearing, capable of handling lubrication, eccentric load, and misalignment situations, is established in this study. Simulation results of interface pressure, film thickness distribution, flash temperature, and subsurface stress can be obtained with different speeds, misalignment angles, load eccentricity, and roller trimming parameters. It is found that edge trimming can greatly reduce the stress concentration at the edge, and there are optimal trimming parameters to minimize the concentrated stress under normal load and eccentric load. When the eccentric load exceeds a certain angle, the increase in the maximum stress can be very large, which may lead to premature failure of the interface. Meanwhile, the staggering velocity caused by the misalignment of the roller axis also has a certain influence on the distribution of the lubricating film.

A systematic review and net meta-analysis of the effects of different warm-up methods on the acute effects of lower limb explosive strength

ObjectiveTo evaluate the effects of different warm-up methods on the acute effect of lower limb explosive strength with the help of a reticulated meta-analysis system and to track the optimal method.MethodsR software combined with Stata software, version 13.0, was used to analyse the outcome metrics of the 35 included papers. Mean differences (MD) were pooled using a random effects model.Results1) Static combined with dynamic stretching [MD = 1.80, 95% CI: (0.43, 3.20)] and dynamic stretching [MD = 1.60, 95% CI: (0.67, 2.60)] were significantly better than controls in terms of improving countermovement jump height (cm), and the effect of dynamic stretching was influenced by the duration of stretching (I2 = 80.4%), study population (I2 = 77.2%) and age (I2 = 75.6%) as moderating variables, with the most significant effect size for dynamic stretching time of 7–10min. 2) Only dynamic stretching [MD = -0.08, 95% CI: (-0.15, -0.008)] was significantly better than the control group in terms of improving sprint time (s), while static stretching [MD = 0.07, 95% CI: (0.002, 0.13)] showed a significant, negative effect. 3) No results were available to demonstrate a significant difference between other methods, such as foam axis rolling, and the control group.ConclusionThe results of this review indicate that static stretching reduced explosive performance, while the 2 warm-up methods, namely dynamic stretching and static combined with dynamic stretching, were able to significantly improve explosive performance, with dynamic stretching being the most stable and moderated by multiple variables and dynamic stretching for 7–10min producing the best explosive performance. In the future, high-quality studies should be added based on strict adherence to test specifications.

Study on the effect of ocean rolling motion on the thermal–hydraulic performance of supercritical carbon dioxide in horizontal tube

The effect of ocean rolling motion on the flow and heat transfer characteristics of the S-CO2 has been numerically investigated in this article. The results showed that increasing the rolling period makes the influence of rolling motion tend to be gentle. Increasing the maximum rolling angle and the rolling radius will increase the centrifugal and tangential forces on the fluid inside the tube, further making the swing motion of the flow field become more intense. Thus, this directly results in the tube wall temperature oscillation of 10 K to 50 K as well as the total pressure drop fluctuation of about 6%. In addition, the effect of three spatial positions relative to the rolling axis is also investigated. This research work can provide a theoretical reference for the development of marine equipment.

Detection of a Rotating Conveyor Roller Casing Vibrations on a Laboratory Machine

The article describes the basic parts and the overall design of the laboratory machine, which can be used to measure vibrations generated by a rotating conveyor roller attached to the flattened parts of its axis in the cut-outs of the conveyor idler support. On the structurally modified support of the conveyor idler consisting of the insertion of a plastic element placed between the roller axis and the support cut-out, the vibration acceleration values of the rotating roller from symmetric analysis were measured and compared with the values from asymmetric analysis of the traditional roller axis placement in the steel support. The size of the peripheral speed of the roller was determined, during the experimental measurements, by controlling the speed of the electric motor using a frequency converter. The obtained results of the measured values of vibration velocities in three mutually perpendicular planes showed a reduction in vibration values of about 15% when using plastic holders. The paper aims to present one of the possible technical solutions that can limit the vibration values transmitted to the supporting structure of the conveyor belt, generated by the rotating casing of the conveyor roller.

Damping control of polodes, inertia and natural frequencies: Theory and application to automotive suspensions

This paper shows how tunable dampers can help control the instant centre of rotation of a 2D rigid body and its polode in planar motion, which in turn implies that the inertia tensor can also be controlled. For mechanisms equipped with some elasticity the results show that damping can also control their natural frequencies. The foundation of a general theory to control the polode is presented, exploring the chance of an optimal control formulation of the problem via a variational control principle, approached by the LQR (Linear Quadratic Regulator) method, after a suitable linearization. Application to automotive suspension linkages is presented that demonstrates the control of the instant roll centre and axis and consequently its instant roll vibration frequency to optimize the response, when excited by lateral inertia forces.

Driveline System Effects on Powertrain Mounting Optimization for Vibration Isolation under Actual Vehicle Conditions

<div>Vehicle vibration is the key consideration in the early stage of vehicle development. The most dynamic system in a vehicle is the powertrain system, which is a source of various frequency vibration inputs to the vehicle. Mostly for powertrain mounting system design, only the uncoupled powertrain system is considered. However, in real situations, other subsystems are also attached to the powertrain unit. Thereby, assuming only the powertrain unit ignores the dynamic interactions among the powertrain and other systems. To address this shortcoming, a coupled powertrain and driveline mounting system problem is formulated and examined. This 16 DOF problem is constructed around a case of a front engine-based powertrain unit attached to the driveline system, which as an assembly resting on other systems such as chassis, suspensions, axles, and tires. First, the effect of a driveline on torque roll axis and other rigid body modes decoupling is examined analytically in terms of eigensolutions and frequency responses. It is observed from the analysis that when the optimized uncoupled powertrain system is introduced in real vehicle conditions, the vibration isolation level of the powertrain mountings gets degraded. Then, a new improved approach of considering coupled powertrain and driveline systems in the initial design phase itself is proposed. The mounting system parameters such as mount location, mount orientation angle, and stiffness rate are optimized and redesigned for the proposed system. The results of the redesigned system show that the decoupling of the rigid body mode parameters is improved and consequently powertrain vibration performance is also improved in static and dynamic conditions of the vehicle. Overall, the findings of this study suggest that considering the driveline along with the powertrain as a coupled system at the early phase of the mounting system design itself improves the vibration performance of the vehicle during real-life situations.</div>

Assessment of dosimetric impact of interfractional 6D setup error in tongue cancer treated with IMRT and VMAT using daily kV-CBCT.

This study aimed to evaluate the dosimetric influence of 6-dimensional (6D) interfractional setup error in tongue cancer treated with intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) using daily kilovoltage cone-beam computed tomography (kV-CBCT). This retrospective study included 20 tongue cancer patients treated with IMRT (10), VMAT (10), and daily kV-CBCT image guidance. Interfraction 6D setup errors along the lateral, longitudinal, vertical, pitch, roll, and yaw axes were evaluated for 600 CBCTs. Structures in the planning CT were deformed to the CBCT using deformable registration. For each fraction, a reference CBCT structure set with no rotation error was created. The treatment plan was recalculated on the CBCTs with the rotation error (RError), translation error (TError), and translation plus rotation error (T+RError). For targets and organs at risk (OARs), the dosimetric impacts of RError, TError, and T+RError were evaluated without and with moderate correction of setup errors. The maximum dose variation ΔD (%) for D98% in clinical target volumes (CTV): CTV-60, CTV-54, planning target volumes (PTV): PTV-60, and PTV-54 was -1.2%, -1.9%, -12.0%, and -12.3%, respectively, in the T+RError without setup error correction. The maximum ΔD (%) for D98% in CTV-60, CTV-54, PTV-60, and PTV-54 was -1.0%, -1.7%, -9.2%, and -9.5%, respectively, in the T+RError with moderate setup error correction. The dosimetric impact of interfractional 6D setup errors was statistically significant (p < 0.05) for D98% in CTV-60, CTV-54, PTV-60, and PTV-54. The uncorrected interfractional 6D setup errors could significantly impact the delivered dose to targets and OARs in tongue cancer. That emphasized the importance of daily 6D setup error correction in IMRT and VMAT.

Robotic Hummingbird Axial Dynamics and Control near Hovering: A Simulation Model

After a short overview of the COLIBRI project, this paper considers the cycle-averaged flight dynamics of a flapping-wing robot near hovering, taking advantage of the weak coupling between the roll and pitch axes. The system is naturally unstable; it needs to be stabilized actively, which requires an attitude reconstruction. Due to the flapping of the wings, the system is subject to a strong periodic noise at the flapping frequency and its higher harmonics; the resulting axial forces and pitch moments are characterized from experimental data. The flapping noise propagates to the six-axis Inertial Measurement Unit (IMU) consisting of three accelerometers and three gyros. The paper is devoted to attitude reconstruction in the presence of flapping noise representative of flight conditions. Two methods are considered: (i) the complementary filter based on the hovering assumption and (ii) a full-state dynamic observer (Kalman filter). Unlike the complementary filter, the full-state dynamic observer allows the reconstruction of the axial velocity, allowing us to control the hovering without any additional sensor. A numerical simulation is conducted to assess the merit of the two methods using experimental noise data obtained with the COLIBRI robot. The paper discusses the trade-off between noise rejection and stability.

Study on Error Compensation Method of Online Roll Profile Measurement

Flatness and surface quality are important quality indexes of strip steel, and roll wear will directly affect the product's flatness and surface quality. Online roll profile measurement technology can obtain the information of roll profile in real time, guide the optimization of roll change rhythm, and improve the flatness control ability of rolling mill and surface quality of strip product. However, the error caused by roll displacement, clearance, roll thermal crown, and other factors is usually the same order of magnitude as the roll shape or roll wear, or even one order of magnitude higher. So error compensation is the key to ensuring the accuracy of online roll profile measurement. Herein, the position measurement technology of the roll bearing block is considered in the online roll profile measurement, and the measurement error caused by the deviation of the roll axis is separated. The thermal crown model is established to separate the measurement errors caused by the thermal crown. The error compensation model of online roll profile measurement is established, and the simulation calculation is carried out. This error compensation method is of great significance to improve the accuracy of online roll profile measurement and realize the fine management of mill roll in service.

Design and Verification of Carefree Maneuvering Protection for a High Performance Fighter Aircraft

Flight envelope protection for a high-performance aircraft poses a challenge to the designers and involves a time-consuming procedure to verify the provided protection. This paper presents a design approach to protect the aircraft from departure by a command path limiter for a rate command attitude hold controller in both the pitch and roll axes. In this approach, the maximum and minimum rates are scheduled as a function of the dynamic pressure on the basis of the open loop aircraft capabilities. This is then augmented with a novel angle of attack protection that comes into play only when the pilot inputs cause the aircraft to exceed the incidence on the positive or negative side (one sided protection), while maintaining the rate command attitude hold behavior within the normal operational bounds of angle of attack. Traditional methods of piloted simulation with a representative cohort of pilots can be time consuming to set up and may not give sufficient confidence whether a departure protection scheme is effective. To address this, a unique multi-modal search using genetic algorithm is developed to verify that this command path protection is able to achieve carefree maneuvering of a fighter aircraft in its entire flight envelope. The sequence of rapid pilot control inputs is coded into a chromosome. The multi-modal genetic algorithm then uses operators like cross-over and mutation on a starting population of chromosomes to evolve new inputs sequences which are then run to obtain the aircraft response. The cost function of the genetic algorithm which is constructed from the aircraft time response is designed to favor the search for multiple maxima which drive the aircraft to departure. The open domain ADMIRE model has been used to demonstrate the approach. Results indicate that the command path design proposed in this paper can be used to protect against departure and the novel multi-modal genetic algorithm helps to verify the departure protection.

Vulnerability of Ship with a Large Breadth to Draught Ratio Against Excessive Acceleration Criteria

A ship having a large breadth and small draught may have a large metacentric height. Therefore, the ship could be vulnerable to the excessive acceleration criteria. In order to investigate the vulnerability, an Indonesian ro-ro ferry with breadth to draught ratio of 5.31 was used to apply the criteria. The lateral acceleration and the long-term probability index with limited scatter wave data of International Maritim Organization were calculated for passenger or crew accommodation in full loading condition. The calculation was conducted for variation of metacentric height using the JONSWAP spectrum to modelled irregular wave. The results show that the maximum vertical distance from the roll axis to comply with the criteria level 1 was 8.7% of ship breadth. The metacentric height comply with the criteria level 1 for the passenger or crew accommodation was 1.4 metres corresponding to 8.7% of ship breadth. The maximum wave height comply with the criteria level 2 was 5 metres. These results show that the excessive acceleration criteria can be used to assess stability of a ship with large ratio between breadth and draught. The vertical distance from the roll axis has more significant effect on the lateral acceleration than the metacentric height.

Revisiting Reentry Roll Resonance

This paper revisits the subject of reentry roll resonance, which occurs when the roll rate and pitch frequency become equal in a spinning reentry vehicle. A first-principles model is developed and analyzed numerically and by using a reduced-order pendulum model for the relative phase of the roll and pitch/yaw axes. The results show good qualitative agreement with recent flight data and provide a natural physical interpretation. Based on the model it is suggested that sustained roll resonance depends primarily on the initial phase relationship between the pitch and roll axes, in addition to the vehicle moments of inertia and the vehicle symmetry. Finally the model is used to propose a mechanism for sustained resonance in vehicles spinning about a major axis, a condition previously thought to be forbidden.

Teaching NeuroImages: Vertebral artery compression by head tilt around the roll axis diagnosed by transcranial Doppler

A 59-year-old man reported transient vertigo and diplopia during leftward head tilt around the roll axis. Neurologic examination was unremarkable with the head erect or tilted. Magnetic resonance angiography of the head and neck showed hypoplasia of the right vertebral artery (figure 1). Transcranial Doppler waveform was monitored during leftward head tilt. The left vertebral artery flow velocity decreased with tilt, and abruptly increased after returning to erect posture (figure 2). Vertebral artery can be stretched or kinked by head rotation or tilt,1,2 typically at the C1-2 level.1 Transcranial Doppler could be helpful in diagnosis of such cases.

A spirocyclic backbone accesses new conformational space in an extended, dipole-stabilized foldamer

Most aromatic foldamers adopt uniform secondary structures, offering limited potential for the exploration of conformational space and the formation of tertiary structures. Here we report the incorporation of spiro bis-lactams to allow controlled rotation of the backbone of an iteratively synthesised foldamer. This enables precise control of foldamer shape along two orthogonal directions, likened to the aeronautical yaw and roll axes. XRD, NMR and computational data suggest that homo-oligomers adopt an extended right-handed helix with a pitch of over 30 Å, approximately that of B-DNA. Compatibility with extant foldamers to form hetero-oligomers is demonstrated, allowing greater structural complexity and function in future hybrid foldamer designs.

Assessing the dependence of vehicle rollover on many factors based on new 4D graphs.

In this paper, the author proposes a novel solution to evaluate the dependence between the maximum roll angle and the minimum vertical force at the wheel on the vehicle's height and speed. 4D graphs that fully and clearly describe the dependence between parameters are used to replace conventional 2D and 3D graphs. A complex dynamic model is established to describe the vehicle's oscillations when steering. Calculations and simulations are performed using Simulink® software with many specific cases. In all cases, the input values such as steering angle, speed, and distance from RA (roll axis) to CG (the center of gravity), all change flexibly. According to the paper's findings, the roll angle will rise once speed or height increases. In addition, the maximum roll angle increases significantly once both the velocity and the height increase. This causes the vertical force at the wheel to drop suddenly, and rollover may occur if this value reduces to zero. 4D graphs provide a more specific and intuitive assessment of vehicle rollovers.