Roll Rate Research Articles

Effect of Hot Rolling Rate on the Structure and Texture Condition of Plates of the Al – Si – Mg Alloy System

The method of orientation microscopy (EBSD) is used to study the structure and texture over the thickness of hot-rolled plate of aluminum alloy of the Al – Si – Mg system. In the surface layers of plates there are mainly shear components of the texture, and in the central layers a rolled texture is observed. With use of fast hot rolling rates alloy surface layers undergo recrystallization that substantially changes structure homogeneity over the plate thickness.

Autopilot design for an aircraft by using Luenberger observer design

PurposeThe purpose of this paper is to design linear quadratic regulator (LQR) based Luenberger observer for the estimation of unknown states of aircraft.Design/methodology/approachIn this paper, the LQR-based Luenberger observer is deliberated for autonomous level flight of unmanned aerial vehicle (UAV) which has been attained productively. Various modes like phugoid and roll modes are exploited for controlling the rates of UAV. The Luenberger observer is exploited for estimation of the mysterious states of the system. The rates of roll, yaw and pitch are used as an input to the observer, while the remaining states such as velocities and angles have been anticipated. The main advantage of using Luenberger observer was to reduce the cost of the system which has been achieved lucratively. The Luenberger observer proposes sturdiness at the rate of completion to conquest over the turmoil and insecurities to overcome the privileged recital. The FlightGear simulator is exploited for the endorsement of the recital of the Luenberger observer-based autopilot. The level flight has been subjugated lucratively and has been legitimated by exploiting the FlightGear simulator. The authenticated and the validated results are offered in this paper. Microsoft Visual Studio has been engaged as a medium between the MATLAB and FlightGear Simulator.FindingsThe suggested observer based on LQR ensures the lucrative approximation of the unknown states of the system as well as the successful level flight of the system. The Luenberger observer is used for approximation of states while LQR is used as controller.Originality/valueIn this research work, not only the estimation of unknown states of both longitudinal and lateral model is made but also the level flight is achieved by using those estimated states and the autopilot is validated by using the FlightGear, while in most of the research work only the estimation is made of only longitudinal or lateral model.

Coefficients Extraction of Model and Constrained Controller Design for Fin-Roll Stabilizer System in a Fishing Boat

This study aimed at stabilizing and decreasing the fishing boat's nonlinear roll motion using a fin-roll stabilizer. To do so, numerical and analytical modeling have been introduced. In addition, a numerical method and empirical formulas for calculating the coefficients of the model are used. A Computational fluid dynamics (CFD) method is employed to analyze both the fluid flow and its effect on the fin performance. Constrained linear quadratic regulator (LQR) controller is designed and used to control the roll motion in the presence of operational constraints of the fin's actuator. To boost the validity of results, the performance of this controller is compared with a conventional proportional-integral-derivative (PID) controller. Simulation results demonstrate the significant amount of reduction in roll amplitude. 1. Introduction Roll motion is one of the most important motions of a ship at sea. The accelerations due to wave-induced roll motions negatively influence a fishing boat's performance by limiting the comfort, workability, and safety (Perez & Blanke 2012). The roll stabilization systems have widely been studied for more than three decades (Perez & Blanke 2012), and various types of antirolling devices have been introduced to reduce the undesirable roll motion (Lloyd 1989). The use of an active fin stabilizer has been considered as the most effective antirolling technique for ships normally operating at some forward speeds (Sellars & Martin 1992). This reduces the roll motion by controlling the mechanical angle of the fin according to the ship roll angle and roll rate (Stallard 1961). There are two main constraints of fin stabilizers including saturation of the mechanical fin angle and dynamic stall (Ghaemi et al. 2009). These two constraints cause a performance degradation in the fishing boats. Dynamic stall is a nonlinear phenomenon caused by unsteady hydrodynamic effects leading to roll moment loss when the angle of attack exceeds a certain threshold (Perez & Goodwin 2008). Also, it depends on the lift coefficient which can be changed in line with the effective angle of attack between the flow and the fin. Therefore, to analyze the behavior of fin and calculate the lift coefficient, the experimental results (Lee et al. 2000), the computational fluid dynamics (CFD) method, (Surendran et al. 2007) and the empirical formulas are used (Whicker & Fehlner 1958). Taylan (1996, 1999, 2000) studied the nonlinear roll motion model. In those studies, the nonlinear restoring terms were considered as a third order polynomial. Likewise, the nonlinear damping term was regarded as a second order polynomial. In the study by Surendran and Venkata Ramana Reddy (2002), a comprehensive research was conducted regarding the roll dynamics of a Ro-Ro ship, taking into account the many types of combinations of loads in linear and nonlinear forms. In the study by Alarçin (2014), the nonlinear mathematical model of roll was introduced for a fishing boat in the presence of wave disturbance.

Combined simulation of heavy truck stability under sudden and discontinuous direction change of crosswind with computational fluid dynamics and multi-body system vehicle dynamics software

The method of yaw model is used to establish aerodynamic property of heavy truck in computational fluid dynamics and wind tunnel test. A model of multi-body system simulation for heavy truck is built based on design and measure data from body, driving system, steering system, braking system, and powertrain system with TruckSim. Aerodynamic reference point of Society of Automotive Engineers (SAE) and aerodynamic coefficients are as the interface to integrate computational fluid dynamics and multi-body system simulation. A sudden and discontinuous direction change of crosswind is set up in multi-body system simulation, and dynamic performance of the heavy truck is performed by open-loop and closed-loop simulation. Under the given simulation case, lateral offset of the truck for open-loop simulation is 1.55 m and more than that for closed-loop simulation; the roll rate range of both simulations is −1.49°/s to 1.695°/s, the range of lateral acceleration is −0.497 m/s2 to 0.447 m/s2 in open-loop simulation, the range of lateral acceleration is −0.467 m/s2 to 0.434 m/s2 in closed-loop simulation; the range of yaw rate is −1.36°/s to 1.284°/s in open-loop simulation, the range of yaw rate is −0.703°/s to 0.815°/s in closed-loop simulation. The results show that combined simulation of the heavy truck stability can be completed by computational fluid dynamics and multi-body system software under sudden and discontinuous direction change of crosswind.

Strategic Coalitions and Agenda-Setting in Fragmented Congresses: How the PRI Sets the Legislative Agenda in Mexico

This essay suggests a theory of strategic legislative agenda control. It argues that a single party can effectively set the agenda under majoritarian gatekeeping rules without obtaining majority or even plurality status. The agenda-setting party need not be the median party in the assembly nor supported by executive-led parliamentary coalitions. The Mexican Chamber of Deputies provides a case study of how majoritarian gatekeeping and political context establish the conditions necessary for one-party-led agenda-setting in a fragmented congress with or without enduring coalitions. The failure of opposition coalitions to roll the ‘Partido Revolucionario Institucional’ evinces that party's ability to set the agenda through strategic coalition formation since 2000. High levels of party unity combined with strategic positioning have allowed the PRI to do so. The strategic nature of the PRI's coalition-making is documented and analyzed in the context of its historically pragmatic approach to coalition-making. The argument is supported by roll-call data analysis, using WNOMINATE, WRice scores, and roll rates.

Design and experimental validation of control algorithm for vehicle hydraulic active stabilizer bar system

This paper presents a novel active roll control algorithm for vehicle hydraulic active stabilizer bar system. The mechanical structure and control scheme of hydraulic active stabilizer bar system is detailed. The anti-roll torque controller is designed with “Proportional-Integral-Differential (PID) + feedforward” algorithm to calculate the total anti-roll torque. A lateral acceleration gain and roll rate damping are added into “PID + feedforward” controller, which can improve vehicle roll dynamic response. The torque distributor is introduced based on fuzzy–PID algorithm to distribute the anti-roll torque of front and rear stabilizer bar dynamically, which can improve vehicle yaw dynamics response. The actuator controller is used for realizing the closed-loop control of the actuators displacement and generating the accurate anti-roll torque. The hardware-in-the-loop simulation platform is established based on AutoBox and active stabilizer bar actuators. The hardware-in-the-loop experiment is carried out under typical maneuvers. Experimental results show that the proposed control algorithm improves the vehicle roll and yaw dynamics response, which can enhance the vehicle roll stability, yaw stability, and ride comfort.

A Case Study of Bank Accounting Practices on Reserves for Impairment of Credit Deduction

The objectivity of the customers' feasibility is biased with the interest of the targeted credit that they are assigned to achieve. In addition, it remains an obstacle forsmall and medium class banks to be dependant on the long historical credit data of each customer to determine the credit-value loss (CKPN). Â This study uses a method of a qualitative case study with structured stages for determining the formation of credit-value loss (CKPN) with creditrisk+ model. The purpose of this study is to reveal the accounting practice of establishing CKPN with creditrisk+ model. The results show that the ATMR method caused BPR banks to provide a very large recovery fund when compared with CreditRisk+ method. Other findings reveal that the approach of ATMR is not maximized in producing accurate measure of credit risk and in accordance with the actual condition. This study contributes to providing an alternative to the determination of CKPN in addition to using ATMR and roll rate analysis model by the banks. For the regulators and professional organizations of the Indonesian Institute of Accountants, they can use it as sources of information to evaluate the application of PSAK 55, especially in determining the CKPN.Â

An experimental and modelling approach for improving utilization rate of the cold roll forming production line

This paper presents theoretical approach and complex experimental research which was conducted within the real production conditions of cold roll forming channel sections. The experimental investigation was focused on forming forces measuring on the rolls and the deflections of roll stands due to the forming loads. The comparison and analysis of the obtained experimental results was performed for the majority roll stands. Based on the experimental results mathematical modelling of the forming a force‐roll load was performed by response surface methodology for different values of the input parameters of the process: material properties, sheet thickness, and sheet width. The defined force model and experimental research show insufficient energetic and technological utilization of the existing production line. After the conducted research in the production process a sheet thickness of up to 1.40 mm is used instead of 0.70 mm, and the utilization of the installed energy has increased from 20 % to 75 %. This is confirmed by the measured deformations of the roll stands and the energy consumption of the powered electric motor. Through realized modernization of the cold roll forming production line, 30 % higher productivity is achieved, which is a result of optimal number planning of roll forming stations and approximately the same load of all roll stands, as well as the higher flow rate of the profile sheet.

VEHIOT: Design and Evaluation of an IoT Architecture Based on Low-Cost Devices to Be Embedded in Production Vehicles.

Nowadays, the current vehicles are incorporating control systems in order to improve their stability and handling. These control systems need to know the vehicle dynamics through the variables (lateral acceleration, roll rate, roll angle, sideslip angle, etc.) that are obtained or estimated from sensors. For this goal, it is necessary to mount on vehicles not only low-cost sensors, but also low-cost embedded systems, which allow acquiring data from sensors and executing the developed algorithms to estimate and to control with novel higher speed computing. All these devices have to be integrated in an adequate architecture with enough performance in terms of accuracy, reliability and processing time. In this article, an architecture to carry out the estimation and control of vehicle dynamics has been developed. This architecture was designed considering the basic principles of IoT and integrates low-cost sensors and embedded hardware for orchestrating the experiments. A comparison of two different low-cost systems in terms of accuracy, acquisition time and reliability has been done. Both devices have been compared with the VBOX device from Racelogic, which has been used as the ground truth. The comparison has been made from tests carried out in a real vehicle. The lateral acceleration and roll rate have been analyzed in order to quantify the error of these devices.

Systematics of constant roll inflation

We study constant roll inflation systematically. This is a regime, in which the slow roll approximation can be violated. It has long been thought that this approximation is necessary for agreement with observations. However, recently it was understood that there can be inflationary models with a constant, and not necessarily small, rate of roll that are both stable and compatible with the observational constraint ns ≈ 1. We investigate systematically the condition for such a constant-roll regime. In the process, we find a whole new class of inflationary models, in addition to the known solutions. We show that the new models are stable under scalar perturbations. Finally, we find a part of their parameter space, in which they produce a nearly scale-invariant scalar power spectrum, as needed for observational viability.

New perspectives on constant-roll inflation

We study constant-roll inflation using the β-function formalism. We show that the constant rate of the inflaton roll is translated into a first order differential equation for the β-function which can be solved easily. The solutions to this equation correspond to the usual constant-roll models. We then construct, by perturbing these exact solutions, more general classes of models that satisfy the constant-roll equation asymptotically. In the case of an asymptotic power law solution, these corrections naturally provide an end to the inflationary phase. Interestingly, while from a theoretical point of view (in particular in terms of the holographic interpretation) these models are intrinsically different from standard slow-roll inflation, they may have phenomenological predictions in good agreement with present cosmological data.

Simultaneous estimation of the road attributes and the vehicle states

This paper aims to contribute to the developpement of the advanced driver-assistance systems (ADAS). The automated system which is provided by ADAS to the vehicle is proven to reduce road fatalities, by minimising the human error. The main objective in this work is to strengthen ADAS by information like estimated road profile. An unknown inputs observer is developed, to estimate in real time the road bank, slope and profile together with the vehicle states, based on measurements of roll and pitch rates, and the lateral, longitudinal and centre of wheels acceleration. Thus, this virtual sensor, based on an unknown input observer presented here, provides the variables needed by advanced driver assistance systems. Simulations conducted in this work show that the designed observer can reproduce correctly the vehicle dynamics and can be easily implemented as an embedded system in the vehicle.

Numerical Simulation and Experimental Study on the Interface Bonding of Stainless Steel Clad Plate

The rolling temperature and rate of thickness reduction directly affect the interface bonding quality,mechanical properties and microstructure of stainless steel clad plate. In order to obtain reasonable rolling process parameters, the multi-pass rolling processes of Q345R/316L stainless steel clad plate were simulated by the DEFORM software package. The distributions of stress, strain, and microstructure fields of the clad plate at different rolling temperatures and reduction rates were investigated. The bonding state of the interface was determined and the change rules governing the grain size of the rolled substrate layer also were analyzed. Vacuum hot-rolling tests were carried out to characterize the microstructure and mechanical properties. It was found that the higher the rolling temperature, the lower was the reduction rate needed to realize the interface bonding. However, too high temperatures produce a higher fraction of coarse grains, which affects the overall mechanical properties of the clad plate. It was concluded from the tests and numerical results that rolling temperature of 1150°C and reduction rate exceeding 50%, stainless allow one to produce steel clad plates with high interface bonding quality and excellent microstructure.

Dynamic Inversion Control of Quadrotor with a Suspended Load

In this paper, I have tackled the problem of a quadrotor with a suspended load using nonlinear dynamic inversion method. The main purpose of this paper is to present a new dynamics of the UAV-load system using Newton’s law. I applied dynamic inversion control for directing the UAV to the desired coordinates and simultaneously minimizing the sway angle of the suspended mass. I have carried the entire simulation in the inertial frame. My approach is to use an outer loop controller for maintaining the position and an inner loop controller for the desired roll, pitch and yaw rate. I have performed the simulations on MATLAB.

Singular Perturbation Control for the Longitudinal and Lateral-Directional Flight Dynamics of a UAV

This paper presents a singular perturbation control strategy for regulating both the longitudinal and the lateral-directional flight dynamics of an Unmanned Aerial Vehicle (UAV). The proposed control strategy is based on a double four-time-scale (4TS) decomposition of the longitudinal and lateral-directional dynamics. The longitudinal dynamics include the altitude, velocity, pitch, and flight path angle dynamics, with the control signals being the elevator deflection and the throttle position, while the lateral-directional dynamics include the side-slip angle, bank angle, yaw rate and roll rate dynamics, with the control signals being the aileron and rudder deflection. The nonlinear control strategy drives the system to follow references in the aerodynamic velocity, the flight path angle and the load factor, which in return provides references in bank angle, side-slip angle and yaw rate. In addition, the control strategy allows to select the desired dynamics for all the singularly perturbed subsystems. Numerical results are included for a realistic nonlinear UAV model, including control saturation and presenting control robustness capabilities under unmodelled dynamics.

Analysis and suppression of a self-excitation vibration via internal stiffness and damping nonlinearity

This work concerns the usage of the internal stiffness and damping nonlinearity for vibration suppression in a van der Pol–type mechanical self-excitation system. Changing the vertical or horizontal damping could limit the growth of the flow-induced instability. Applying harmonic balance method, the energy transfer for the self-excitation vibration is investigated through the limit circle. The steady amplitude of the limit circle is a key parameter that could be used to evaluate the effectiveness of the self-excitation oscillation suppressing. Increasing horizontal damping could reduce the rate of roll on for the steady amplitude curve of the limit circle, but the critical flow velocity for the limit circle occurring is minimally affected. Increasing vertical damping could increase the critical flow velocity, but the rate of the roll on is virtually unaffected when the parameters are properly chosen.

Studies and research regarding optimal cargo load of a transport van using carmaker software

The main objective of this paper is to find the optimal positioning of a cargo load in a given van, using simulations implemented in CarMaker. The chosen cargo weight is 1000 kg (close to the limit of the chosen van, 1350 kg), and the factors that are used as input are: the type of driver (aggressive, defensive and normal – for each type of driver the longitudinal acceleration and decelerations vary and also the maximum velocity and lateral), the road that was kept the same and was built so that the driver has to follow several curves left and then to the right with decreasing curve radius, the manoeuvres are set as a maximum speed on the given road (100 km/h, adapted by the driver so that the van stays on the road), and the tires were kept the same. The 1-ton load was placed in the van in 9 points on two planes with different heights and all the simulations were compared to the unloaded van. Also, an 80-kg driver was input. The results that were exported from all the simulations were: the total damp force of all the wheels, the yaw angle, the pitch angle, the roll angle, the yaw rate (measured in degrees/second), the pitch rate and the roll rate all correlated to the velocity of the vehicle. CarMaker offers a lot of output information regarding the vehicle behaviour due to the complexity of the equations behind the software. Another advantage is the coupling possibility with AVL InMotion so that the virtual engine is replaced with the real engine coupled to the DynoRoad dynamometer in the Testing and Homologation Laboratory of the Automotive Engineering and Transport Department (Technical University of Cluj-Napoca). To ensure the uniformity of the forces that occur while driving on a road with curves, in all the elements of the suspension system, the load must be placed in the centre area of the van. However, the idea of the simulations was the lack of side doors of some vans that require an un-cantered placement of the cargo.

Optimization of rollover stability for a three-wheeler vehicle

An auto rickshaw is a three-wheeled motor vehicle commonly found in Asia, with one front steering wheel and two driven wheels at the back. In automobiles, suspension is used to keep the wheels planted during motion. The trailing arm suspension generally found in Indian automobiles has its roll center on the ground. The vehicle’s center of gravity is above the ground, which creates a moment during vehicle turning known as the roll moment. When this roll moment exceeds a certain limit, the vehicle becomes unstable. Roll rate can be expressed as degrees per lateral acceleration of the vehicle’s sprung mass, and is influenced by factors such as wheel rate, motion ratio, and suspension rate. In order to determine an optimized three-wheeler suspension setup, a matrix selection method was used, in which every available suspension type in the market is rated based on selected suspension parameters such as handling, dynamics, and simplicity. From the overall weightage, each suspension type is analyzed and the most appropriate is selected. In order to achieve the objective of improving the overall rollover stability, certain modifications have been applied in the selected suspension design. Generally, if the roll rate of a specific vehicle axle is high, the percentage of weight transfer on the axle will also be high. By improving roll stiffness, the amount of roll can be decreased, and by optimizing the motion ratio, the roll moment can be controlled, thereby increasing the overall rollover stability.

How decoherence affects the probability of slow-roll eternal inflation

Slow-roll inflation can become eternal if the quantum variance of the inflaton field around its slowly rolling classical trajectory is converted into a distribution of classical spacetimes inflating at different rates, and if the variance is large enough compared to the rate of classical rolling that the probability of an increased rate of expansion is sufficiently high. Both of these criteria depend sensitively on whether and how perturbation modes of the inflaton interact and decohere. Decoherence is inevitable as a result of gravitationally-sourced interactions whose strength are proportional to the slow-roll parameters. However, the weakness of these interactions means that decoherence is typically delayed until several Hubble times after modes grow beyond the Hubble scale. We present perturbative evidence that decoherence of long-wavelength inflaton modes indeed leads to an ensemble of classical spacetimes with differing cosmological evolutions. We introduce the notion of per-branch observables---expectation values with respect to the different decohered branches of the wave function---and show that the evolution of modes on individual branches varies from branch to branch. Thus single-field slow-roll inflation fulfills the quantum-mechanical criteria required for the validity of the standard picture of eternal inflation. For a given potential, the delayed decoherence can lead to slight quantitative adjustments to the regime in which the inflaton undergoes eternal inflation.

Three Dimensional Guidance against Helix Maneuver with Unknown Turning Rate

This paper deals with target interception that is performing a three dimensional helix maneuver with unknown turning rate. In practice neither the turning rate is known nor do its components thus they need estimation. The guidance law requires the turning rate vector. The simplest approach to deal with the 3D guidance and estimation is to consider three separate problems. In reality there is coupling between axes in the equations of motion in 3D. Two representations of helix trajectory that exploit this coupling are presented, the partially-coupled and the strongly-coupled representations. These representations are used to derive guidance schemes - estimator and guidance law. Simulation results compare the RMS miss distance and control effort of the different representations in the Pareto plane. It is shown that the usage of guidance laws that takes into account the coupling leads to improved performance especially when the barrel roll rate turning rate is unknown.