Roll Rate Research Articles

Double anti-roll bar hardware-in-loop experiment for active anti-roll control system

Active anti-roll bar (AARB) is a cheaper alternative for a fully active suspension system, which can be adapted into passenger cars, made possible by today’s technology. AARB minimizes body roll and improve ride comfort. In this paper, the design of a Hardware-in-loop (HIL) test bench is presented. The HIL test bench is able to test dual AARB system, each for front and rear of a car respectively. HIL testing will allow designer to analyze and validate the performance of the proposed AARB system before it could be implemented in a real car. This paper focuses on the practicality and adaptability of implementing Fuzzy based PID controllers into the AARB system. HIL experiment compares the performance of proposed Self-Tuning Fuzzy PI-PD (STF PI-PD) controller against the PI-PD Type Fuzzy Logic Controller (PI-PD Type FLC) and Self-Tuning Fuzzy PID (STF PID) controllers. STF PID controller was proposed by previous researchers for an AARB system. Experimental results suggest that the proposed AARB system, which incorporates STF PI-PD controller is able to reduce 87.68 % of roll angle and 50.04 % in roll rate in average, thus improving the vehicle dynamics. STF PI-PD controller significantly outperforms both STF PID and PI-PD Type FLC controllers in various handling tests.

Tobit Kalman filter with fading measurements

This paper is concerned with the Tobit Kalman filtering problem for a class of discrete time-varying systems with both censored and fading measurements. The censored measurements are described by the Tobit measurement model and the fading measurements are characterized by the Lth-order Rice fading channel model capable of accounting for not only the packet dropout but also the communication phenomenon. The measurement fading occurs in a random way where the fading probabilities are regulated by a set of mutually independent Gaussian random variables. By resorting to the state augmentation technique and the orthogonality projection principle, the Tobit Kalman filter (TKF) is designed in the presence of fading measurements. In the course of filter design, several state-augmentation-induced terms are introduced, all of which can be calculated recursively or off-line. A numerical example concerning the estimation of ballistic roll rates is provided to illustrate the usefulness of the proposed filter.

Overexpression of miR529a confers enhanced resistance to oxidative stress in rice (Oryza sativa L.).

Overexpressing miR529a can enhance oxidative stress resistance by targeting OsSPL2 and OsSPL14 genes that can regulate the expression of their downstream SOD and POD related genes. MicroRNAs are involved in the regulation of plant developmental and physiological processes, and their expression can be altered when plants suffered environment stresses, including salt, oxidative, drought and Cadmium. The expression of microRNA529 (miR529) can be induced under oxidative stress. However, its biological function under abiotic stress responses is still unclear. In this study, miR529a was overexpressed to investigate the function of miR529a under oxidative stress in rice. Our results demonstrated that the expression of miR529a can be induced by exogenous H2O2, and overexpressing miR529a can increase plant tolerance to high level of H2O2, resulting in increased seed germination rate, root tip cell viability, reduced leaf rolling rate and chlorophyll retention. The expression of oxidative stress responsive genes and the activities of superoxide dismutase (SOD) and peroxidase (POD) were increased in miR529a overexpression plant, which could help to reduce redundant reactive oxygen species (ROS). Furthermore, only OsSPL2 and OsSPL14 were targeted by miR529a in rice seedlings, repressing their expression in miR529aOE plants could lead to strengthen plant tolerance to oxidation stress. Our study provided the evidence that overexpression of miR529a could strengthen oxidation resistance, and its target genes OsSPL2 and OsSPL14 were responsible for oxidative tolerance, implied the manipulation of miR529a and its target genes regulation on H2O2 related response genes could improve oxidative stress tolerance in rice.

Design and flight test of the generic micro-aerial vehicle (GenMAV) utilizing piezoelectric conformal flight control actuation

A novel morphing control surface design employing piezoelectric macro-fiber composite actuators is compared to a servo-actuated system. The comprehensive comparison including aerodynamics, size, weight, power, bandwidth, and reliability has been extended to include flight test comparisons. Three flight vehicles were designed, built, and evaluated: a servo-controlled generic micro-aerial vehicle aircraft and two conformal actuator controlled versions based on thick and thin wing designs. Flight agility and control response of the morphing-actuated and servo-actuated configurations were quantified through state measurement during identical automated maneuvers. The morphing actuation scheme demonstrated control bandwidth that was an order of magnitude greater than for the servo-actuated system, but showed a 12% decrease in roll rate when compared to the servo-actuated baseline aircraft. The flight vehicles allowed system-level comparisons of conventional and morphing control, where conformal actuation occupied less volume, consumed equivalent power as micro servos and provided effective control power for maneuvering.

Design and stable flight of a 21 g insect-like tailless flapping wing micro air vehicle with angular rates feedback control

An insect-like tailless flapping wing micro air vehicle (FW-MAV) without feedback control eventually becomes unstable after takeoff. Flying an insect-like tailless FW-MAV is more challenging than flying a bird-like tailed FW-MAV, due to the difference in control principles. This work introduces the design and controlled flight of an insect-like tailless FW-MAV, named KUBeetle. A combination of four-bar linkage and pulley-string mechanisms was used to develop a lightweight flapping mechanism that could achieve a high flapping amplitude of approximately 190°. Clap-and-flings at dorsal and ventral stroke reversals were implemented to enhance vertical force. In the absence of a control surface at the tail, adjustment of the location of the trailing edges at the wing roots to modulate the rotational angle of the wings was used to generate control moments for the attitude control. Measurements by a 6-axis load cell showed that the control mechanism produced reasonable pitch, roll and yaw moments according to the corresponding control inputs. The control mechanism was integrated with three sub-micro servos to realize the pitch, roll and yaw controls. A simple PD feedback controller was implemented for flight stability with an onboard microcontroller and a gyroscope that sensed the pitch, roll and yaw rates. Several flight tests demonstrated that the tailless KUBeetle could successfully perform a vertical climb, then hover and loiter within a 0.3 m ground radius with small variations in pitch and roll body angles.

Comparison of PID and Fuzzy Controller for Position Control of AR.Drone

This paper describes the implementation of the PID Controller to control the position of the AR.Drone in the x-y-z. This position control scheme uses three PID controllers to maintain the position of x, y and z using the signal control pitch, roll and vertical rate. PID Controller implemented on AR.Drone 2.0 and then tested in an indoor space. The performance of the controller will be compared with Fuzzy Logic Controller schemes that have been implemented previously. The results show that the PID Controller generate a response with rise time less than 3 seconds at the x and y position with around 25% overshoot. The result for z position give better result without overshoot. The comparison between fuzzy logic and PID Controller indicates that the results of the PID controller is better although there is overshoot.

Rotor-state feedback control design to improve helicopter turbulence alleviation in hover

A helicopter flight control system with rotor-state feedback to improve turbulence alleviation in hover is presented. First, a flight dynamic model coupled with turbulence model is developed and validated. Then, an integrated control strategy with a rotor-state feedback control law is proposed based on the baseline control system. The feedback gains of body and rotor states are designed in synergy to improve turbulence alleviation in the interested frequency range of handling qualities. Subsequently, the effects of the rotor-state feedback gains on both the stability of rotor dynamics and helicopter turbulence alleviation are analyzed in detail. Finally, the effectiveness of the integrated control system is evaluated with linear analysis in frequency domain and nonlinear simulation in time domain. The results indicate that with the rotor-state feedback control law integrated into the control system, the helicopter turbulence alleviation in the interested frequency range is improved with less degradation in helicopter stability margins, and the roll and pitch rate responses of helicopter to turbulence, measured with Root-Mean-Square (RMS) values, are reduced by more than 50% and 35% respectively.

Design of an integrated control system to enhance vehicle roll and lateral dynamics

Besides lateral instability, one major threat to all ground vehicles, especially SUVs, is the danger of rollover during cornering. A coordination strategy based on fuzzy logic has been devised to coordinate the sub-controls; namely, active steering, active differential, active brake and a novel active roll control system. Independent study of each sub-control as well as an analysis of their inter-relationship has been carried out. The coordination strategy is supposed to resolve the conflict among control targets – which are sideslip regulation, yaw rate tracking, lateral acceleration tracking and roll motion control – all of which are to be done while maintaining the driver’s desired longitudinal acceleration. Thus, a compromise must be reached. Vehicle sideslip angle and yaw rate were considered to be the criteria for lateral stability; and a combination of roll angle, roll rate and lateral load transfer was selected as the criterion for roll stability. The results of simulations on two SUV models in CarSim software indicate that the integrated controller can successfully restore vehicles’ stability in critical condition.

Using Instrumented Revenue Vehicles to Inspect Track Integrity and Rolling Stock Performance in a Passenger Network During Peak Times

This paper discusses the use of Instrumented Revenue Vehicles (IRV), developed by Institute of Railway Technology at Monash University, to evaluate track condition and assess the dynamic performance of the rolling stock during peak operating hours in a passenger network in Indonesia between Lamongon and Surabaya. Assessment of track condition and the dynamic responses of the vehicle is crucial in setting safe operating speeds, in the development of economical proactive maintenance plans and maximizing throughput. The track condition and vehicle responses for this study were measured using accelerometers, spring nest displacement sensors and yaw, roll and pitch rate sensors. Sensors were strategically mounted on various locations of the wheelset, bogie and carriage to evaluate track condition, monitor load transmission and measure dynamic response of the in-service vehicle over multiple runs. The acquired data was analyzed and used to develop visual hot spot maps of the track to determine regions of high dynamic response. The acceleration measurements from the unsprung mass were used to evaluate the rail vertical profiles. This evaluation was carried out in frequency domain and the low frequency components were filtered out to remove contributions from long wavelength track features. A web based reporting system was used to provide plots and figures to communicate the results. Results presented demonstrate the ability of the IRV system to assess health conditions of track, identify regions of degradation and quantify the severity of the dynamic response.This project was sponsored by the Australian Indonesian Centre (AIC) and conducted collaboratively by Institute of Railway Technology (IRT), Monash University and Institut Teknologi Sepuluh Nopember (ITS)

Analysis of microstructural effects on mechanical properties of copper alloys

Abstract With the aim of obtaining copper alloys with favorable mechanical properties (high strength and high ductility) for various engineering applications, the microstructural characteristics of two conventional copper alloys — an aluminum bronze (AlBC; Cu–Al 9.3 –Fe 3.8 –Ni 2 –Mn 0.8 ) and a brass (HB: Cu–Al 4 –Zn 25 –Fe 3 –Mn 3.8 ) — and a recently developed aluminum bronze (CADZ: Cu–Al 10.5 –Fe 3.1 –Ni 3.5 –Mn 1.1 –Sn 3.7 ), were controlled by subjecting the alloys to two different processes (rolling and casting) under various conditions. For the rolling process, the rolling rate and temperature were varied, whereas for the casting process, the solidification rate was varied. Microstructural characteristics, as examined by electron backscatter diffraction analysis, were found to differ among the alloys. Complicated microstructures formed in CADZ led to high hardness and high tensile strength ( σ UTS ), but low ductility ( e f ). For CADZ, casting at a high solidification rate allowed an increase in ductility to be obtained as a result of fine-grained structure and low internal stress. In contrast, high ductility (with a fracture strain of more than 30%) was found for both cast AlBC and cast HB; moreover, both of these alloys possessed high tensile strength when produced by warm rolling at 473 K. For CADZ, on the other hand, no clear effect of rolling on tensile strength could be found, owing to the many microcracks caused by its brittleness. The results of this study indicate that copper alloys with excellent mechanical properties can be produced. This is especially the case for the conventional alloys, with a high tensile strength σ UTS = 900 MPa and a high fracture strain e f = 10% being obtained for warm-rolled brass.

Comparison of PID and Fuzzy Controller for Position Control of AR.Drone

This paper describes the implementation of the PID Controller to control the position of the AR.Drone in the x-y-z. This position control scheme uses three PID controllers to maintain the position of x, y and z using the signal control pitch, roll and vertical rate. PID Controller implemented on AR.Drone 2.0 and then tested in an indoor space. The performance of the controller will be compared with Fuzzy Logic Controller schemes that have been implemented previously. The results show that the PID Controller generate a response with rise time less than 3 seconds at the x and y position with around 25% overshoot. The result for z position give better result without overshoot. The comparison between fuzzy logic and PID Controller indicates that the results of the PID controller is better although there is overshoot.

Dynamic stability of rolling missiles employing a two-loop autopilot with consideration for the radome aberration parasitic feedback loop

The dynamic stability of a radar homing rolling missile is extremely complex due to the interaction of the parasitic radome aberration feedback loop and the cross-coupling between the pitch and yaw, which are problems that have not been presented in previous studies. This paper presents mathematical models representative of the parasitic radome aberration feedback loop and proportional navigation guidance (PNG) system with a two-loop autopilot for rolling missile guidance based on reasonable assumptions. A PNG system equation is further proposed in the form of a complex summation. Based on the proposed mathematical models, the sufficient and necessary condition for the dynamic stability of the rolling missile is analytically derived according to the stability criterion of a system with complex coefficients. The proposed dynamic stability condition is verified by numerical simulation. Moreover, the stable region is obtained by solving the dynamic stability condition under different cases. An analysis of the effects of system parameters indicates that the stable region of a rolling missile is smaller than that of a non-rolling missile. Furthermore, it is shown that the stable region is affected by a number of factors, such as the rolling rate and the total delay angle. The dynamic stability condition derived in this paper is useful for evaluating the stability of a rolling missile with consideration for the parasitic radome aberration feedback loop, and the conclusions obtained can provide guidance for the design of PNG systems for rolling missiles.

Dynamic characteristics analysis and flight control design for oblique wing aircraft

The movement characteristics and control response of oblique wing aircraft (OWA) are highly coupled between the longitudinal and lateral-directional axes and present obvious nonlinearity. Only with the implementation of flight control systems can flying qualities be satisfied. This article investigates the dynamic modeling of an OWA and analyzes its dynamic characteristics. Furthermore, a flight control law based on model-reference dynamic inversion is designed and verified. Calculations and simulations show that OWA can be trimmed by rolling a bank angle and deflecting the triaxial control surfaces in a coordinated way. The oblique wing greatly affects longitudinal motion. The short-period mode is highly coupled between longitudinal and lateral motion, and the bank angle also occurs in phugoid mode. However, the effects of an oblique wing on lateral mode shape are relatively small. For inherent control characteristics, symmetric deflection of the horizontal tail will generate not only longitudinal motion but also a large rolling rate. Rolling moment and pitching moment caused by aileron deflection will reinforce motion coupling, but rudder deflection has relatively little effect on longitudinal motion. Closed-loop simulations demonstrate that the flight control law can achieve decoupling control for OWA and guarantee a satisfactory dynamic performance.

Effect of Rolling with Cyclic Movement of Rolls Method on Structure and Hardness of CuCr0.6 Alloy

A novel severe plastic deformation method entitled rolling with cyclic movement of rolls was proposed to fabricate ultrafine grained CuCr0.6 copper alloy. The alloy in the solution treated conditions was processed by rolling with cyclic movement of rolls method by using process parameters as amplitude of rolls movement (A = 0.9 mm), frequency of rolls movement (f = 1 Hz), rolling reduction (eh =50%) and rolling rate (v = 1, v = 2, v = 3 rpm). Light microscopy, scanning electron microscopy and a electron backscattering diffraction detector, and scanning transmission electron microscopy were used for microstructural characterization, and hardness tests for a preliminary assessment of mechanical properties. Quantitative studies of the average diameter of the subgrains d (μm) and the average diameter of the grains D (μm) were performed using the scanning electron microscopy/electron backscattering diffraction method. Misorientation angles were analyzed by the Kikuchi-line technique using TSLOIM software. The results show that the samples underwent very high strain at the lateral areas and smaller at the central areas. As a result, the microstructure became heterogeneous and remained unchanged with change in compression rate. The transverse movement of rolls causes in the material significant effect of refining structure in peripheral areas of sample.

Robust model predictive control employed to the container ship roll motion using fin-stabilizer

AbstractThe aim of this paper is to find the non-linear behavior of a container ship roll motion by using fin-roll stabilizer and robust model predictive control (RMPC). To do so, numerical and analytical modeling has been introduced for the roll motion. Computational fluid dynamics method was employed to determine the hydrodynamic lift of the fin at various angles. RMPC was designed and used to control the non-linear roll motion in the presence of disturbances, uncertainties, which were caused by the irregular sea waves, and operational constraints of fin’s actuator. To boost the validity of our results, the performance of this controller was compared with a conventional PID (Proportional-Integral-Derivative) controller. Simulation results indicated the significant amount of reduction in roll amplitude and roll rate.

Riding performance on a conventional bicycle and a pedelec in low speed exercises: Objective and subjective evaluation of middle-aged and older persons

This study investigated cycling performance of middle-aged (30–45yearsold; n=30) versus older (65+ years; n=31) participants during low-speed tasks for which stabilization skills are known to be important. Additionally, participants’ self-ratings of their cycling skills and performance were assessed. Participants rode once on a conventional bicycle and once on a pedelec, in counterbalanced order. Three standardized tasks were performed: (1) low-speed cycling, (2) acceleration from a standstill, and (3) shoulder check. During Tasks 1and3, the mean absolute steering angle (a measure of the cyclist’s steering activity) and the mean absolute roll rate (a measure of the amount of angular movement of the frame) were significantly greater for older participants than for middle-aged participants. These large lateral motions among older cyclists may indicate a difficulty to control the inherently unstable system. Comparing the conventional bicycle and the pedelec, participants reached a 16km/h threshold speed in Task 2 sooner on the pedelec, an effect that was most pronounced among the older participants. Correlations between skills assessed with the Cycling Skill Inventory and actual measures of cycling performance were mostly not statistically significant. This indicates that self-reported motor-tactical and safety skills are not strongly predictive of measures of actual cycling performance. Our findings add to the existing knowledge on self-assessment of cycling skills, and suggest that age-related changes in psychomotor and sensory functions pose hazards for cycling safety.

Repeatability of a dynamic rollover test system

ABSTRACTObjective: The goal of this study was to characterize the rollover crash and to evaluate the repeatability of the Dynamic Rollover Test System (DRoTS) in terms of initial roof-to-ground contact conditions, vehicle kinematics, road reaction forces, and vehicle deformation.Methods: Four rollover crash tests were performed on 2 pairs of replicate vehicles (2 sedan tests and 2 compact multipurpose van [MPV] tests), instrumented with a custom inertial measurement unit to measure vehicle and global kinematics and string potentiometers to measure pillar deformation time histories. The road was instrumented with load cells to measure reaction loads and an optical encoder to measure road velocity. Laser scans of pre- and posttest vehicles were taken to provide detailed deformation maps.Results: Initial conditions were found to be repeatable, with the largest difference seen in drop height of 20 mm; roll rate, roll angle, pitch angle, road velocity, drop velocity, mass, and moment of inertia were all 7% different or less. Vehicle kinematics (roll rate, road speed, roll and pitch angle, global Z′ acceleration, and global Z′ velocity) were similar throughout the impact; however, differences were seen in the sedan tests because of a vehicle fixation problem and differences were seen in the MPV tests due to an increase in reaction forces during leading side impact likely caused by disparities in roll angle (3° difference) and mass properties (2.2% in moment of inertia [MOI], 53.5 mm difference in center of gravity [CG] location).Conclusions: Despite those issues, kinetic and deformation measures showed a high degree of repeatability, which is necessary for assessing injury risk in rollover because roof strength positively correlates with injury risk (Brumbelow 2009). Improvements of the test equipment and matching mass properties will ensure highly repeatable initial conditions, vehicle kinematics, kinetics, and deformations.

Split-time method for estimation of probability of capsizing caused by pure loss of stability

The paper reviews a multi-year research effort for using the split-time method to calculate the probability of ship capsizing due to pure loss of stability in irregular waves. The idea of the split-time method is to separate the complex problem into two less complex problems: a non-rare problem that involves the upcrossing of an intermediate level of roll and a rare problem that focuses on capsizing after an upcrossing. An initial implementation using a dynamic model with piecewise linear stiffness, which can be considered to be the simplest model of capsizing in beam seas, led to the concept of critical roll rate as the smallest roll rate at the instant of upcrossing that inevitably leads to capsizing. The extension of the split-time method to pure loss of stability required the consideration of the change of roll stiffness in waves and led to calculating the critical roll rate at each upcrossing. A metric of the likelihood of capsizing has been defined as the difference between the observed and critical roll rate at the instances of upcrossing. The probability of capsizing after upcrossing is found by approximating the tail with the Generalized Pareto Distribution.

Development of Flight Control System and Troubleshooting on Flight Test of a Tilt-Rotor Unmanned Aerial Vehicle

The full results of troubleshooting process related to the flight control system of a tilt-rotor type UAV in the flight tests are described. Flight tests were conducted in helicopter, conversion, and airplane modes. The vehicle was flown using automatic functions, which include speed-hold, altitude-hold, heading-hold, guidance modes, as well as automatic take-off and landing. Many unexpected problems occurred during the envelope expansion tests which were mostly under those automatic functions. The anomalies in helicopter mode include vortex ring state (VRS), long delay in the automatic take-off, and the initial overshoot in the automatic landing. In contrast, the anomalies in conversion mode are untrimmed AOS oscillation and the calibration errors of the air data sensors. The problems of low damping in rotor speed and roll rate responses are found in airplane mode. Once all of the known problems had been solved, the vehicle in airplane mode gradually reached the maximum design speed of 440km/h at the operation altitude of 3km. This paper also presents a comprehensive detailing of the control systems of the Tilt-rotor unmanned air vehicle (UAV).

Roll rate perceptual thresholds in active and passive curve driving simulation

In driving simulation, simulator tilt is used to reproduce sustained linear acceleration. In order to feel realistic, this tilt is performed at a rate below the human tilt rate detection threshold, which is usually assumed constant. However, it is known that many factors affect the threshold, such as visual information, simulator motion in additional directions, or the driver’s active effort required for controlling the vehicle. Here we investigated the effect of these factors on the roll rate detection threshold during simulated curve driving. Ten participants reported whether they detected roll motion in multiple trials during simulated curve driving, while roll rate was varied over trials. Roll rate detection thresholds were measured under four conditions. In the first three conditions, participants were moved passively through a curve with the following: (i) roll only in darkness; (ii) combined roll/sway in darkness; (iii) combined roll/sway and visual information. In the fourth (iv) condition participants actively drove through the curve. The results showed that roll rate thresholds in simulated curve driving increase, that is, sensitivity decreases, when the roll tilt is combined with sway motion. Moreover, an active control task seemed to further increase the detection threshold, that is, impair motion sensitivity, but with large individual differences. We hypothesize that this is related to the level of immersion during the task.