The vital purpose of a vehicle suspension system is to isolate the car body and hence passengers, from roadway unevenness disturbances. Implementation of passive suspension systems has continuously improved disconnection from disturbances through available deflection constraints to provide maximum isolation. In the majority of relevant reported research studies, a quarter car is modelled as moving vertically straight for both a viscous damper and a stiffness spring. The motivation for this study, reported here, is to extend the modelling to take account of the actual configuration of a test rig system. Accordingly, a new passive suspension system model is presented, which includes nonlinear lubricant friction forces that affect the linear support body bearings. The friction model established relies on dynamic system analysis and the fact of slipping body on lubricant bearings; this model captures most of the friction behaviours that have been observed experimentally. The suspension model is composed of a car body and wheel unit, and only vertical motion (bounce mode) is addressed. In addition, an active actuator is used to generate the system inputs as a road simulator. Therefore, a nonlinear hydraulic actuator, including the dynamic of servovalve and proportional鈥搃ntegral controller model, is established. This study is validated by experimental work, with simulations achieving C++compiler. As a result, a good agreement is obtained between the experimental and simulation results, that is, the passive suspension system with considered nonlinear friction and the nonlinear hydraulic actuator with servovalve equation models are entirely accurate and useful. The suggested proportional鈥搃ntegral controller successfully derives the hydraulic actuator to validate the control scheme. The ride comfort and handling response are close to that expected for the passive suspension system with road disturbances.
Friction is a very complex phenomenon, arising from the contact of surfaces. In many engineering applications, the success of models in predicting experimental results remains strongly sensitive to the friction model. In practice, it is not possible to determine an exact friction model; however, based on observation results and dynamic systems analysis, a recently proposed model of nonlinear friction at linear supported lubricant bearings is investigated. This model involved static friction, stiction region, and dynamic friction, which is consisted of transition, Stribeck effect, Coulomb and viscous frictions. On the other hand, this model is applied in the passive suspension system. Accordingly, a new quarter-car passive suspension model with the implementation of friction force is considered. Also, a vital experimental and simulation aspect is the generation of system input. Therefore, a nonlinear hydraulic actuator used, modelling this actuator including the dynamic of servovalve derived by the proportional-integral (PI) controller, is prepared. This study is validated experimentally, with simulation achieving C++ compiler. Consequently, a good agreement between the experimental and simulation results is obtained, i.e., the nonlinear friction, passive suspension system and nonlinear hydraulic actuator models are entirely accurate and useful.
Fully active electrohydraulic control of a quarter-car test rig is considered from both a modelling and experimental point of view. This paper develops a nonlinear active hydraulic design for the active suspension system, which improves the inherent trade-off between ride quality and suspension travel. The novelty is in the use of pole assessment controller to drive a nonlinear active suspension with a new insight into the model through consideration of a new term, friction forces. Therefore, this model has taken into account the dynamic inclination angle [Formula: see text] between linkage and actuator regardless of the fact that the designer made an only vertical motion (bounce mode) of the wheel and body units. The second contribution of this paper is that it investigated the control force generation, therefore, the nonlinear hydraulic actuator whose effective bandwidth depends on the magnitude of the suspension travel, which incorporates the dynamic equation of servovalve, is deeply researched. The nonlinear friction model is accurately established, which relies on the dynamics system analysis and the fact of slipping the body on lubricant supported bearings; this model will caption all the friction behaviours that have been observed experimentally. In addition, the hydraulic system is used to generate the system inputs as a road simulator. The controller smoothly shifts its focus between the conflicting objectives of ride comfort and rattle space utilisation, softening the suspension when suspension travel is small and stiffening it as it approaches the travel limits. Thus, the nonlinear design allows the closed-loop system to behave differently in different operating regions. The improvement achieved with our design is illustrated through comparative experiments and simulations. C++ compiler environment is used to simulate the physical system to be controlled. The results show good servo control and fast regulation of abrupt disturbances.
To achieve a high level of performance, frictional effects have to be addressed by considering an accurate friction model, such that the resulting model faithfully simulates all observed types of friction behaviour. A nonlinear friction model is developed based on observed measurement results and dynamic system analysis. The model includes a stiction effect, a linear term (viscous friction), a nonlinear term (Coulomb friction) and an extra component at low velocities (Stribeck effect). During acceleration, the magnitude of the frictional force at just beyond zero velocity decreases due to the Stribeck effect, which means the influence of friction reduces from direct contact with bearings and body into the mixed lubrication mode at low velocity. This could be due to lubricant film behaviour. In respect of acceleration and deceleration when the direction changes for the mass body, friction almost depends on this direction, while the static frictional force exhibits springlike characteristics. However, friction is not determined by current velocity alone, it also depends on the history of the relative wheel and body velocities and movements, which are responsible for friction hysteresis behaviour.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations鈥揷itations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright 漏 2024 scite LLC. All rights reserved.
Made with 馃挋 for researchers
Part of the Research Solutions Family.