Roll Torque Research Articles

Optimization of a passive roll absorber for robotic fish based on tune mass damper.

The robotic fish utilizes a bio-inspired undulatory propulsion system to achieve high swimming performance. However, significant roll motion has been observed at the head when the tail oscillates at certain frequencies, adversely affecting both perception accuracy and propulsion efficiency. In this paper, the roll torque acting on the robotic fish is theoretically analyzed and decomposed into gravitational, inertial, and hydrodynamic components. Resonance is identified as a key factor amplifying the roll response. To mitigate this roll and enhance stability, a passive roll absorber based on tuned mass damper is designed. A simplified rolling structure is dynamically modeled to optimize absorber parameters. Experiments are conducted to quantify the roll torque experienced by the robotic fish, with the effectiveness of the absorber verified on both the simplified model and the robotic fish. Results show that the maximum roll angle of the simplified system under harmonic load decreases from 98 degrees to 29 degrees, representing a reduction of over 70%, while a 25.1% reduction is achieved on the robotic fish.

Model of Dynamic Mechanical Parameters and Vibration Analysis in Hot Rolling

As the core equipment of metal shaping processing, the vibration problem of rolling mill seriously affects the product quality and production efficiency. To address the problem of the limited prediction of mill vibration due to small sample data in non-steady states, we propose to predict dynamic mechanical parameters (rolling force and rolling torque) based on the TCN-LSTM step strategy transfer model. The prediction accuracies of the TCN-LSTM step strategy transfer model under 1000 sets of training data reach 95.8% and 93.2%, respectively, and at the same time, it saves the time of training and regulation of the deep learning model and can better meet the needs of online prediction. The horizontal-torsion hot rolling vibration model is further established to quantitatively analyze the relationship between process parameters and mill vibration. The experimental results show that with the vibration suppression measures of 10% reduction of the rolling speed and 10% reduction of the entrance thickness, the horizontal vibration displacement amplitude is reduced from 0.687 × 10−4 m to 0.229 × 10−4 m, and the rotational displacement amplitude is reduced from 0.0273 m to 0.0117 m, which effectively suppresses the vibration of the mill and improves the stability of the rolling process.

Attitude stability control for 6WID unmanned ground vehicle during steering: A collaborative controller considering minimizing tire slip energy loss

The instability of vehicle attitude and wheel slippage during turning on complex roads are key factors affecting the operational efficiency and accuracy of a variable wheelbase six-wheel independent drive unmanned ground vehicle (6WID UGV), posing a serious threat to driving safety. This article proposes a hierarchical coordinated controller to improve the attitude stability of a 6WID UGV equipped with interconnected active hydro pneumatic suspension (IAHPS) and reduce tire slip energy loss. Firstly, an integral sliding mode controller with adaptive high-order coupling factor (AHOCF-ISMC) is designed to determine the active anti roll torque required for stable roll attitude. An adaptive high-order coupling factor is introduced in the controller framework to couple physical components with different properties, avoiding overshoot and oscillation caused by integral saturation of the controller. Secondly, based on satisfying the stability of the roll attitude, the lateral stability and longitudinal traction characteristics of the vehicle are constrained and controlled. An optimization function was established to minimize tire slip energy loss within the feasible range of wheel torque determined by lateral and longitudinal control objectives. Thirdly, the particle swarm optimization algorithm was improved (IPSO) by designing adaptive weighting factors and learning factors, and is used to optimize the wheel torque distribution scheme under composite constraint conditions. Finally, the effectiveness of the coordinated controller was tested and validated in different scenarios. The results show that the designed controller has good control performance and robustness without the need to establish an accurate mathematical model, and performs well in terms of economic benefits and application prospects.

Dynamic compensation of the threading speed drop in rolling processes

This paper presents an approach for the dynamic speed drop compensation during threading in rolling processes. The feedforward control design exploits the differential flatness of the mechanical model and accelerates both the rolls and the drive train in a manner such that the acceleration torque is equal to the rolling torque during threading, while simultaneously maintaining the roll at the desired target speed. Ideally, this prevents the speed drop and enhances the quality and stability of the rolling process. The flatness-based feedforward trajectories are optimized in an online fashion to determine the optimal initial roll speed and duration of the acceleration process. An extensive experimental validation on a hot strip finishing mill shows superior performance in terms of various key performance indicators in comparison with a standard overspeed approach.

Kriging and Radial Basis Function Models for Optimized Design of UAV Wing Fences to Reduce Rolling Moment

In the present study, the effects of the wing fence on the wing tip vortices and control surfaces located at the tip of the wing in a flying wing aircraft have been investigated using a numerical method. For the size of the fences, the average dimensions extracted from the wing tip vortices at different angles of attack are used. The basic determining parameter is the rolling torque coefficient, which is tried to be shown by employing a parametric study of the flow behavior in different situations of fence placement. These effects on the rolling torque of the aircraft are measured due to the presence of the split drag rudder control system. In this study, the fences were installed at three different heights and three different positions along the length of the wing, which were investigated at angles of attack of 7 to 16 degrees. The next stage of the research is to design the dimensions of the fence using the single-objective optimization method (a method to find the best solution for a problem with a specific goal). The designing of the fences at three points based on the dimensions of the wing tip vortex is carried out with the computational fluid dynamics (CFD) method (CFD is a computational method that uses physical laws to predict the behavior of fluids.). The aim of this research is to achieve the best design that converges to an optimal solution with minimum time and cost (CFD solution is long). However, CFD analysis requires a lot of computational time. To address this challenge, we employed a hybrid learning model comprising the radial basis function (RBF), a type of artificial neural network, and Kriging, a Gaussian process-based interpolation technique. The dataset for training the hybrid model was obtained from numerical solutions of CFD simulations involving a fence placed at various locations on the wing. Additionally, a genetic algorithm was employed as the optimization method in all instances where it was required. Using the power of machine learning techniques helped us identify the optimal placement of the fence to prevent it from being engulfed by the vortex and to optimize the utilization of the split drag system, yielding significant improvements.

Correction to: Numerical and analytical estimation of rolling force and torque in hot strip rolling

Correction to: Numerical and analytical estimation of rolling force and torque in hot strip rolling

Sierpinski-fractal inspired ultra-broadband UV-NIR meta absorber: Notable impact on the self-stabilization of light-sail or solar-sail

Light's fundamental characteristics can enable an extensive plethora of possibilities. In a recent study, to the best of our knowledge, it has been reported for the very first time that meta-absorber-based light-sails (mainly for solar sails) can be a potential alternative to reflector-based light-sails. However, a notable property of practical light-sail or solar sail is self-stabilization for real-world applications, which has never been investigated for meta-absorber-based light-sails. This article presents a highly efficient ultra-wideband (UWB) metamaterial absorber, followed by numerous numerical analyses to demonstrate its effectiveness. The absorptivity has been shown to be greater than 90% for the entire spectrum of ultra-violet (UV) to near-infrared (NIR), i.e., 300–1800 nm. Furthermore, we extend the absorber's applicability to light-sail's stabilization. One of the notable findings of this work: the subwavelength metamaterial unit cell showcases exceptional stability while being subjected to a conventional plane-polarized source. It showed that the ‘absorption’ assists in mitigating the destabilizing effects of the plane-polarized source. The utilization of the Sierpinski-Carpet-Meta-Absorber (SCMA), a fractal-based ultra-wideband (UWB) metamaterial, represents a compelling prospect as an alternative to traditional reflectors in the development of advanced light-sails for space exploration, owing to its capacity to enhance optical force and facilitate self-stabilization. Our results indicate that the combination of the unique properties of the metamaterial would enable a significant advancement over current attitude control by demonstrating an approach to induce a roll torque on the sail, which is a current limitation in present state-of-the-art technology.

Numerical and analytical estimation of rolling force and torque in hot strip rolling

Numerical and analytical estimation of rolling force and torque in hot strip rolling

Design and Flight Performance of a Bio-Inspired Hover-Capable Flapping-Wing Micro Air Vehicle with Tail Wing

A key challenge in flapping-wing micro air vehicle (FWMAV) design is to generate high aerodynamic force/torque for improving the vehicle’s maneuverability. This paper presents a bio-inspired hover-capable flapping-wing micro air vehicle, named RoboFly.S, using a cross-tail wing to adjust attitude. We propose a novel flapping mechanism composed of a two-stage linkage mechanism, which has a large flapping angle and high reliability. Combined with the experimentally optimized wings, this flapping mechanism can generate more than 34 g of lift with a total wingspan of 16.5 cm, which is obviously superior to other FWMAVs of the same size. Aerodynamic force/torque measurement systems are used to observe and measure the flapping wing and aerodynamic data of the vehicle. RoboFly.S realizes attitude control utilizing the deflection of the cross-tail wing. Through the design and experiments with tail wing parameters, it is proved that this control method can generate a pitch torque of 2.2 N·mm and a roll torque of 3.55 N·mm with no loss of lift. Flight tests show that the endurance of RoboFly.S can reach more than 2.5 min without interferences. Moreover, the vehicle can carry a load of 3.4 g for flight, which demonstrates its ability to carry sensors for carrying out tasks.

Application of machine learning methods for the prediction of roll force and torque during plate rolling of micro-alloyed steel

Machine learning technique is extensively used to establish the relationship between non-linear data sets which cannot be described mathematically and thus an exact analytic model is either intractable or too time-consuming to develop. During hot rolling, the effect of process parameters that cannot be captured in mathematical models, such as roll dimensions and its wear, the inter-pass time between rolling passes, temperature variation has been incorporated using multivariate supervised machine learning technique for accurate prediction of roll force and torque during plate rolling of micro-alloyed steel. An ensemble method was used to combine various machine learning techniques and average them to develop one final predictive model. K-cross validation of the model was carried out to validate the results and ensure the model gets the correct pattern of data. Root mean square error of ensemble roll force model was compared with roll force calculation using Sims theory. It was found that the machine learning model can predict the roll force and torque accurately as it takes care of various non-linear process variables which cannot be accounted for mathematically. The R-value of the machine learning model was >98 %, whereas it was 92.2 % for roll force calculation using Sims theory.

Analysis of Mechanical Parameters in Multi-Pass Asymmetrical Rolling of Strip by Slab Method.

Mechanical parameters, time consumption and energy consumption are important considerations in the application of a certain rolling process. This study aims to investigate characteristics of the roll force, roll torque, roll power, rolling time and total work in multi-pass asymmetrical rolling of strip. Mathematic models were built using the slab method to calculate parameters in the asymmetrical rolling process, and the characteristics of these parameters were analyzed on the basis of simulation results. Mechanical parameters are affected by the change of deformation region type. When the speed ratio is less than the critical speed ratio, the roll force, absolute values of roll torque and roll power are found to increase with the increase in the speed ratio. After the speed ratio reaches the critical speed ratio, the roll force, roll torque and lower roll power keep constant, but the upper roll power continues increasing. The upper roll torque and upper roll power required by asymmetrical rolling are much greater than that by symmetrical rolling, which indicates that stronger drive shafts and more powerful drive motors are required by asymmetrical rolling. Compared with symmetrical rolling, asymmetrical rolling requires less roll force to obtain the same thickness reduction, especially for thin and hard strips. Rolling time can be saved at the cost of more energy consumption by using asymmetrical rolling with the same roll force to attain the same final thickness. The results and conclusions of this study can provide a reference for mill design and application of asymmetrical rolling in strip manufacturing.

A combined measurement method of thrust vector and roll torque for low power Hall-effect thrusters

A combined method for measuring the thrust vector and roll torque of low-power Hall-effect thrusters is proposed, using a conventional torsional thrust pendulum, with a measurement accuracy of a few tens of micro-Newton meters. The 300–500 W class Hall-effect thruster is mounted horizontally on the pendulum, whose motion is determined only by the radial thrust vector and rolling torque of the thrusters. The contribution of the two components of a Hall-effect thruster is analyzed through the method of changing the position of accelerator and external hollow cathode, with the accelerator contributing a significant portion of the radial thrust vector and increasing linearly with thruster anode power. And the external hollow cathode contributing at a magnitude of one hundred micro-Newtons, in the direction opposite to the cathode. The combining method provides a way to measure the deviation angle of the stationary EP thrusters, an analysis of the contribution of the accelerator and the external hollow cathode, and a method for decreasing the deviation angle of a Hall-effect thruster by counteracting the effects of these two components.

Characteristics of the Linear Motor for Electrified High-Speed Maglev Transportation in the Rotational Motions Caused by Asymmetry Transverse Air-Gaps

The electromagnetic characteristics and running stability of the linear motor for electrified Maglev transportation under rotational motions caused by asymmetry transverse air-gaps are calculated and analyzed. Firstly, considering the end effect and the shape of the vehicle coils, the formulas of levitation and guidance currents, levitation and guidance forces, rolling torque, yawing torque, coupling stiffness between lateral and rolling direction, coupling stiffness between lateral and yawing direction and equivalent guidance stiffness are derived. Secondly, the variations of rolling torque, yawing torque, guidance force and levitation force with different lateral displacement, rolling angle and yawing angle are predicted. Then the two coupling stiffnesses and the equivalent guidance stiffness at different operating speeds are investigated. Finally, in order to verify the analysis results, not only the 3-D FEM model is established, but also the experiments are carried out. It shows that the combined levitation and guidance electrodynamic suspension (EDS) maglev train will roll and yaw, and its levitation height also changes after being disturbed laterally. In addition, the train will run more stably when being disturbed laterally as running speed increases.

Hot profiled rolling of C40 steel: production variable’s effect on rolling performance

ABSTRACT The usage of C40 steel bars is common in ships, mechanical, metallurgical, automobile, military hardware, and electrical construction fields. During manufacturing of these bars, roll force (RF), roll torque (RT), cropping loss (CL) and drive energy (DE) are important production variables that must be monitored for high-quality output, scrap reduction, and mill safety with minimum consumption of energy. Roll RPM, temperature of bloom, roll gap, bloom cross-section area, and diameter of roll are process characteristics that influence these response parameters. The impact of process variables on response variables during C40 steel rolling is probed in this research. To replicate the rolling procedure, FORGE® NxT 1.1 was employed. Following statistical testing, the simulated findings were validated utilizing data from experiments acquired in a bar rolling plant. The results of an analysis of variance were used to find significant model terms. There have been constructed regression models demonstrating the link between the response parameters and the process parameters.

Relative roll control of satellite docking using electromagnetic coils

An electromagnetic coil topology and its control strategy, which can be incorporated into the electromagnetic docking device, have been proposed for the relative roll control of two satellites in space. The target satellite and the chaser satellite are respectively embarked with four and six coils evenly arranged around the docking axis. All the coils on the target satellite are Direct Current (DC) energized, while the currents in the coils of the chaser satellite are regulated to achieve the relative roll control. The electromagnetic force/torque model is built by utilizing the frequently-used far field model. Based on the fundamental components extracted from that model, this paper proposes a real-time magnetic moment vector distribution formula that simply generates a constant roll torque. This paper not only presents an equation for calculating the relative roll angle through the Euler angles of two satellites, but also an equation that converts the roll torque setpoint to the setpoints of the coil currents. A 3-closed-loop positioning controller composed of angle, angular velocity, and current loop is developed. The proposed topology is verified by finite element simulation, and the control strategy is validated by dynamics simulation and ground-based tests.

A new model for thermal-mechanical coupled of gradient temperature rolling force based on geometrical unified yield criterion

In order to precisely describe the yield deformation behavior of various materials, a generalized yield criterion known as geometrical unified (GU) yield criterion is firstly established in this paper. Based on this yield criterion, an analytical rolling force model of gradient temperature rolling process was established, and the impact of the temperature field was taken into consideration. The GU yield criterion is a function of shear tension ratio, and the classical yield criteria can be obtained as its special cases. The gradient temperature rolling process of an ultra-heavy plate was analyzed depending on the GU yield criterion, and the corresponding energy functional was established. In the meanwhile, the temperature field expression was developed by taking temperature permeability into account. Finally, the analytical model of the force and energy parameters of the gradient temperature rolling process was constructed by fusing the temperature field with the energy functional. The model can very precisely estimate the rolling force and rolling torque when compared to the measured data. The errors of the rolling force and rolling torque are less than 3.27 %.

Numerical assessment of interstand tensions in continuous hot rolling processes of flat and long products

The paper deals with the calculation of interstand tensions in continuous rolling mills.In the rolling mill industry, continuous measurement and data collection of roll forces, roll torques, temperatures and roll velocities is possible. However, the important process parameter of interstand tensions is not directly measurable and no direct calculation of the interstand tensions is possible. The interstand tensions couple the effects of subsequent roll gaps and should therefore by known for a holistic recalculation of the process. It is straightforward to calculate the effects of the tensions on roll forces, torques and the stock velocity. The inverse problem of calculating the acting interstand tensions including their effects from the process parameters is of greater interest but also of a higher complexity, because the interactions between all the stands in the rolling mill must be regarded. The present paper aims at filling this research gap by presenting a mathematical model to solve the inverse problem by a linearization of the tensions influences in the rolling mill. The present model does not require measured roll forces or torques to find the interstand tensions, only the rotational velocities of the rolls and the rolling parameters (material, temperature, pass schedule or pass design) must be known. Tension-dependent spread is considered by an empirical sub-model. Results are shown for the tension distributions in strip and rod mills. The results indicate that the present friction conditions and the entry size of the rolled stock have a high impact on the tension distributions.

Application of Variable Gauge Rolling Technology for Plate to Reduce the Head Impact

The Variable Gauge Rolling (VGR) technology is adopted for plate rolling. Two passes are treated as a group, with reducing the head reduction, increasing the tail reduction, to reduce the peak impact torque of the head, and give full play to the equipment capacity in the stable rolling stage to increase the pass reduction. The prediction models of plate width and length, rolling force and torque in VGR process are established. The using strategy of VGR are determined, and two methods for increasing reduction are put forward. The main body and head and tail sections of the rolled plate are calculated separated. The reduction corresponding to the target rolling torque is calculated by Newton iterative method, and pass schedule distribution of VGR process is shown. The VGR technology is applied for plate rolling process. The practical application shows that the influence of head impact in the plate rolling process can be reduced by using VGR. The torque amplification coefficient decreases linearly with the increase of gauge variation, and rolling passes number can be reduced through reasonable pass schedule distribution. The practical application shows that VGR can reduce the influence of head impact in the plate rolling process.

Three-dimensional analysis of RF-biased ion optics with misalignments of apertures

Accelerator grid hole shift is a critical reason for erosion failure of optic systems in ion thrusters, which may also cause an unexpected roll torque about the ion beam axis. A three-dimensional (3D) model of ion optics is developed based on a particle-in-cell Monte Carlo collision method to investigate the plasma dynamics and performance of radio frequency (RF) grid systems with misalignments of apertures, which are compared with those in the direct current (DC) grid system. For the benchmark case, the 3D model gives a better agreement with the experiments in the ion energy distribution function (IEDF) compared with the two-dimensional model from a previous publication, with 36.4% and 47.9% relative error reduction of the peak position and full width at half maximum (FWHM), respectively, indicating the effectiveness of the developed 3D model. Simulations show that in the RF grid system the ion beamlet is deflected in the direction opposite to the shift of the accelerator grid hole, while electrons move first in the hole shift direction, and then deflect in the opposite direction. The average ion beamlet deflection angle calculated is consistent with the predictions from linear optical theory in both the RF and DC grid system. The amplitude of beamlet deflection angle fluctuation with time decreases with the increase of RF frequency. When the grid holes shift, the ion beamlet will deflect with the divergence angle almost unchanged in the DC grid system, while the beamlet divergence angle increases in the RF grid system. When RF frequency is low, the big vortex-like structure in the electron velocity phase diagram breaks into small vortices, showing a reduced oscillation intensity. The hole shift also causes high-frequency oscillation in the shift direction. In terms of performance, the RF grid system is more sensitive to grid hole shift than the DC grid system.

Calculation of Deformation-Related Quantities in a Hot-Rolling Process

The hot deformation of metal as a nonlinear system is mathematically described by a local linear model associated with the working conditions using a transfer function (TF) in the Laplace domain. Experimental data (true stress vs. true strain curves) are obtained using the established compressive uniaxial deformation test, where experimental conditions (strain rate and temperature) define the working conditions of the local linear TF model, which is intrinsically a function of strain. Based on the TF model, three important physical quantities of the tested metal are determined exactly: the work done per unit deformation, the average flow stress, and the flow-stress derivative with respect to the strain based on a particular TF. The exactly determined quantities, determined as a function of strain, can replace the previously used approximations in some rolling force and torque calculations.