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48 result(s) for "passive roll"
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The Control of Handling Stability for Active Inward Tilt Vehicles Based on the Phase-Plane Lateral Stability Region
For autonomous vehicles, high-speed cornering can easily lead to degraded handling stability and increased risks of sideslip or even rollover. Therefore, vehicle phase-plane stability-region analysis has become an important topic in active safety-control research. However, most existing studies still construct phase-plane stability regions mainly based on simplified vehicle models, without sufficiently considering the influence of vertical load transfer during cornering on tire lateral forces and stability boundaries. To address this issue, this paper proposes a hierarchical control strategy based on phase-plane analysis for active inward tilt vehicles. This method adopts a three-degree-of-freedom vehicle dynamics model and a tire model. By carefully comparing the phase-plane stability regions of active inward tilt and passive roll vehicles and by further analyzing the state-trajectory convergence characteristics of active inward tilt vehicles under different longitudinal speeds, front wheel steering angles, and road adhesion coefficients, the effects of active inward tilt on stability-region expansion and vehicle-state convergence are revealed. Subsequently, a hierarchical control strategy is proposed as an integrated solution to improve vehicle handling stability. The upper-level controller dynamically adjusts the reference values and objective weights according to whether the vehicle state is located in the stable, critical, or dangerous region. The lower-level NMPC controller optimizes the front wheel steering angle and active suspension forces to achieve coordinated trajectory tracking and stability control. Double lane-change simulation results show that active inward tilt can improve the left–right vertical load distribution and expand the lateral stability region. Compared with passive roll and conventional active inward tilt control, the proposed strategy reduces the phase-plane state convergence area by 68% and 75%, respectively, thereby improving vehicle handling stability and active safety under extreme conditions.
Effect of Active Roll Stabilizer System Performance on Vehicle Stability
To investigate the effect of active roll stabilizer system performance on vehicle stability, it is needed to study the effects of varying speeds of the on-road vehicles under different wheel steer angle on the roll angle, side slip angle and yaw rate on the vehicle stability. For a safe drive, when a vehicle is cornering it should not lose its stability on road. In this paper the response of passive and active roll stabilizer vehicle systems are simulated and compared against each other. The results of the simulation model showed a significant influence of the vehicle speed on the vehicle stability under different wheel steer angles.
Introduction and History
This chapter contains sections titled: Introduction Early Steering History Leaf‐Spring Axles Transverse Leaf Springs Early Independent Fronts Independent Front Suspension Driven Rigid Axles De Dion Rigid Axles Undriven Rigid Axles Independent Rear Driven Independent Rear Undriven Trailing‐Twist Axles Some Unusual Suspensions References
The effects of game-based passive, static stretching, and trunk flexibility on the execution of forward roll in floor exercise: A factorial experimental design
Problem statement: This research aims to elucidate the intricate relationship between training methods (gamebased passive and static stretching) and trunk flexibility, specifically in their influence on the proficiency of executing the forward roll in floor exercises. Purpose: This study aims to explore how training methods (gamebased passive and static stretching) and trunk flexibility affect the forward roll skill in floor exercise. Despite the importance of these training modalities in enhancing physical performance, there remains a gap in understanding their combined impact on the forward roll skill. We hypothesize that the efficacy of training methods and trunk flexibility will significantly influence the execution the forward roll skill. Approach: The study employed an experimental approach with a 2 x 2 factorial design involving randomly selected students (N=40) aged 14.3±8.2 years old, who provided informed consent. Participants were divided into four groups and received either game-based passive or static stretching training over approximately six weeks, with a frequency of three times per week. Trunk flexibility and skill of forward roll data were assessed using the forward trunk flexion test, validity: r= 0.88 and reliability: r = 0.89, and forward rolling test, validity: r = 0.86 and reliability: r = 0.83. Data were analyzed using two-way ANO VA and the Tukey test. Results: Research findings revealed significant differences: (1) game-based passive stretching was more effective than gamebased static stretching in enhancing the skill of forward roll (P<0.05), with an increase of 2.6 vs. 1.5, respectively; (2) individuals with high trunk flexibility benefited more from passive stretching than static stretching (P<0.05); (3) no significant difference was found in individuals with low trunk flexibility (P>0.05); (4) an interaction effect between training method and trunk flexibility was observed (P<0.05). Conclusions: In conclusion, game-based passive stretching is more beneficial for individuals with high trunk flexibility, while game-based static stretching may yield better results for those with low trunk flexibility. However, both modalities can be advantageous for individuals with low trunk flexibility. These findings offer insights for coaches and gymnastics instructors to tailor training programs effectively to enhance the skill of forward roll in floor exercise.
Active and Passive Control Strategies for Ride Stability and Handling Enhancement in Three-Wheelers
Three-wheeled vehicles are increasingly adopted as sustainable transport solutions, but their asymmetric design and lightweight structure make them vulnerable to ride discomfort and rollover instability. This study develops a high-fidelity 12-degrees-of-freedom (DOF) dynamic model in MATLAB/Simulink and MSC ADAMS to analyze and improve ride comfort, handling, and roll stability. The model captures longitudinal, lateral, vertical, roll, pitch, and yaw motions, along with tire dynamics represented through the Magic Formula, and is validated using real-world data from an instrumented test vehicle. In this research, both active and passive control strategies were separately implemented and studied. The active strategy involves an Active Vehicle Roll Dynamics Control (VRDC) system with an active rear suspension to suppress roll and yaw during aggressive maneuvers. The passive strategy focuses on improving rollover resistance by modulating throttle input based on sensor data from gyroscopes, accelerometers, and compasses. Simulation and experimental results show that each strategy, when applied independently, enhances roll stability, reduces yaw rate deviations, and improves handling performance. These findings demonstrate the effectiveness of both approaches in improving the safety and dynamic behavior of electric three-wheeled vehicles under real-world conditions.
An isolation device for near-fault ground motions
SUMMARY Seismic isolation is an appreciable control strategy that reduces the vibrations of structural and nonstructural systems induced by strong ground motions. However, under near‐fault (NF) ground motion, the seismic isolation devices might perform poorly because of large isolator displacements caused by long‐period large velocity and displacement pulses associated with such strong motion. The objective of this paper is to assess the effectiveness of a new seismic isolation device, referred to as roll‐in‐cage (RNC) isolator, in protecting against NF ground motions. The device is intended to achieve a balance in controlling isolator displacement demands and structural accelerations. The RNC isolator provides in a single unit all the necessary functions of rigid support, horizontal flexibility with enhanced stability, and energy dissipation characteristics. Moreover, it is distinguished from other isolation devices by two unique features: (i) it has a built‐in energy‐absorbing buffer to limit the design displacement under strong excitation, and (ii) it has a built‐in linear recentering mechanism that prevents residual displacement after earthquakes. The seismic response of multistory buildings isolated by the RNC isolator is investigated under three recorded NF earthquakes and three synthetic ground motions. The results show that the RNC isolator is a convenient isolation system in protecting against NF earthquakes. Copyright © 2013 John Wiley & Sons, Ltd.
Assembly of Surface-Mounted Devices on Flexible Substrates by Isotropic Conductive Adhesive and Solder and Lifetime Characterization
The assembly of passive components on flexible electronics is essential for the functionalization of circuits. For this purpose, adhesive bonding technology by isotropic conductive adhesive (ICA) is increasingly used in addition to soldering processes. Nevertheless, a comparative study, especially for bending characterization, is not available. In this paper, soldering and conductive adhesive bonding of 0603 and 0402 components on flexible polyimide substrates is compared using the design of experiments methods (DoE), considering failure for shear strength and bending behavior. Various solder pastes and conductive adhesives are used. Process variation also includes curing and soldering profiles, respectively, amount of adhesive, and final surface metallization. Samples created with conductive adhesive H20E, a large amount of adhesive, and a faster curing profile could achieve the highest shear strength. In the bending characterization using adhesive bonding, samples on immersion silver surface finish withstood more cycles to failure than samples on bare copper surface. In comparison, the samples soldered to bare copper surface finish withstood more cycles to failure than the soldered samples on immersion silver surface finish.
Effect of Film Formation Potential on Passive Behavior of Ultra-Fine-Grained 1050 Al Alloy Fabricated via ARB Process
In this work, the effect of film formation potential on the passive behavior of ultra-fine-grained 1050 Al alloy in a borate buffer solution is investigated. For this purpose, the specimens were fabricated via accumulative roll bonding (ARB) process up to 1, 3, 5, and 7 passes. To determine the evolution of microstructure as a function of ARB process, atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used. AFM images revealed that the grain size values decreased as the number of ARB passes increased. Moreover, TEM micrograph showed that mean grain size of the sample reached to about 340 nm after applying 7 passes of ARB. Potentiodynamic polarization plots indicated that, as the number of ARB passes increased, the corrosion and passive current densities decreased. Also, electrochemical impedance spectroscopy measurements showed that at selected applied potential above open circuit potential, the corrosion resistance of the 1050 Al alloy was systematically increased by applying further ARB passes. It was found that passive behavior of the ARBed 1050 Al alloy specimens were improved by reducing the grain size.
A Strategy for Passive Control of Natural Roll-Waves in Power-Law Fluids through Inlet Boundary Conditions
The paper investigates the influence of the inlet boundary condition on the spatial evolution of natural roll-waves in a power-law fluid flowing in steep slope channels. The analysis is carried out numerically, by solving the von Kármán depth-integrated mass and momentum conservation equations, in the long-wave approximation. A second-order accurate scheme is adopted and a small random white-noise is superposed to the discharge at the channel inlet to generate the natural roll-waves train. Both shear-thinning and shear-thickening power-law fluids are investigated, considering uniform, accelerated and decelerated hypercritical profiles as the unperturbed condition. Independently of the unperturbed profile and of the fluid rheology, numerical simulations clearly enlighten the presence of coalescence, coarsening and overtaking processes, as experimentally observed. All the considered statistical parameters indicate that the natural roll-waves spatial evolution is strongly affected by the unperturbed profile. Compared with the uniform condition, at the beginning of roll-waves development an accelerated profile reduces the growth of the roll-waves with a downstream shift of the non-linear wave interaction. The opposite behavior is observed if the roll wave train develops over a decelerated profile. The comparison with the theoretical outcomes of the linearized near wave-front analysis allows the interpretation of this result in terms of stability of the base flow. It is shown that once the coarsening process starts to take place, the roll-waves spatial growth rate is independent of the unperturbed profile. Present results suggest that an appropriate selection of the flow depth at the channel inlet may contribute to control, either enhancing or inhibiting, the formation of a roll-waves train in power-law fluids.
Plio-Quaternary thin-skinned tectonics along the crustal front flexure of the southern Central Andes: a record of the regional stress regime or of local tectonic-driven gravitational processes?
We present here a record of Plio-Pleistocene deformations above the flexural front of the southern Central Andes of Argentina. We combine a seismic profile with structural and geomorphological observations to show that thin-skinned extension located on top of the crustal front flexure is coeval with thin-skinned shortening at the toe of the topographic bulge. The seismic line shows that a flat zone with no internal deformation separates the stretched and shortened domains. Such features are usually interpreted as the result of strike-slip faulting along basement faults, or tangential longitudinal strain folding in the soft sedimentary cover above crustal bending. We propose an alternative linking extension at the apex of the crustal anticline, to basal contraction by the downslope translation of a rigid thin nappe of sediments (30 × 30 km 2 in area) above evaporites at a depth of 700–900 m. The size of such a process is unusually large onshore (630–810 km 3 ) but mimics the gravity gliding observed in deltas and passive margins. Since this process disconnects zones with a shallow stress field from deeper crustal levels, it could allow extension above a compressive deformation front and should not be interpreted merely as a record of the crustal stress regime. Large-scale gravity gliding of the cover down the slope of a structural high could also explain some of the extension observed in mountain hinterlands.