Suspension Model Research Articles

Analysis of Active Suspension Control Based on Improved Fuzzy Neural Network PID

To improve the comfort and smoothness of vehicle driving and reduce the vehicle vibration caused by uneven road surface. In this paper, a new active suspension control strategy is pro-posed by combining a fuzzy neural network and a proportional-integral-derivative (PID) controller, taking body acceleration as the main optimization target and adjusting the parameters of the PID controller in real time. Meanwhile, a fuzzy neural network parameter optimization algorithm combining a particle swarm optimization algorithm and gradient descent method is proposed to realize offline optimization and online fine-tuning of fuzzy neural network parameters. Finally, the active suspension model of a 2-degree-of-freedom 1/4 vehicle is established using MATLAB/Simulink, and the proposed control scheme is verified through simulation studies. The results show that the active suspension system with a particle swarm-optimized fuzzy neural network control method improves the spring mass acceleration, dynamic deflection of suspension, and dynamic tire deformation by 30.4%, 17.8%, and 15.5%, respectively, compared with the passive suspension. In addition, there are also 14.6%, 12.1%, and 11.2% performance improvements, respectively, compared to the PID-controlled active suspension system. These results indicate that the control strategy proposed in this paper can improve the vehicle driving performance and can support the design and development of active suspension systems.

Experimental Investigation on Improving the Comfort of the Vehicle Based on Damping Characteristics of Passive Suspension System using Quarter Car Model

This paper presents detailed experimental research performed on a coil spring that uses the passive mode suspension operation with different road profiles. A quarter car model comprised of two degrees of freedom was developed for ride comfort assessment. The quarter car test rig model for a single independent front suspension that embodies sprung mass, unsprung mass, suspension system and the tire was used. The damping factor is calculated at different road profiles and operating frequencies. An excitation of sinusoidal road profiles with constant amplitude is enforced via an electric motor representing the road profiles. The experimental results of the sprung mass and unsprung mass displacements due to road excitation are measured, recorded and processed. In this study, the sprung mass responses were received for the generated road profiles in contracted and stretched modes of the static compression coil enabling the researchers to select a suitable controller design and innovative materials for the passive, active vehicle suspension systems based on the feedback of the displacement sensors in future developments.

Giant vortex dynamics in confined bacterial turbulence.

We report the numerical evidence of a new state of bacterial turbulence in confined domains. By means of extensive numerical simulations of the Toner-Tu-Swift-Hohenberg model for dense bacterial suspensions in circular geometry, we discover the formation a stable, ordered state in which the angular momentum symmetry is broken. This is achieved by self-organization of a turbulent-like flow into a single, giant vortex of the size of the domain. The giant vortex is surrounded by an annular region close to the boundary, characterized by small-scale, radial vorticity streaks. The average radial velocity profile of the vortex is found to be in agreement with a simple analytical prediction. We also provide an estimate of the temporal and spatial scales of a suitable experimental setup comparable with our numerical findings.

Validation of the CAE model set for a passenger car suspension according to loading criteria

BACKGROUND: Development of numerical methods and technology of computer-aided engineering, used in vehicle design, has reached its high level. Results of virtual experiments cannot be totally relied upon without verifying results obtained with the developed mathematical model. That is why the present paper concentrates on the relevant issue of validation of the CAE models, applicable for vehicle suspension components dynamic load analysis.
 AIMS: Goal of the research is adequacy confirmation of developed requirements to preparation of simulation models, applicable for dynamic load and fatigue analysis, by means of numerical simulation with validation analysis.
 METHODS: CAE models validation is carried out with a comparative method of results obtained from either laboratory or proving ground testing and simulation of a physical object. Strain gauging results are taken for the comparison. The Models are prepaired with using MBS and FEM technologies.
 RESULTS: Validation showed of validation show a good convergence of modelling and experiment results, that confirm adequacy of developed requirements to creation of CAE models, applicable for load and fatigue analysis of vehicle suspension components. The selected convergence evaluation criteria have not been used in similar papers yet and have shown an effective outcome of quantitative and qualitative comparison of loading condition of suspension parts in a variety of boundary conditions of mechanical system simulation.
 CONCLUSIONS: Validated CAE models of a passenger car suspension, developed accelerated loading cycle, the model design and dynamic loading simulation approach can be used for chassis parts load analysis and fatigue prediction during early stages of development and as support of testing.

A Numerical Code for a Wide Range of Compressible Flows on Hybrid Computational Architectures

The major points in the development of the parallel multiplatform multipurpose numerical code solving the full unsteady Navier–Stokes equations are presented. The developed code is primarily designed for running on multi-GPU computational devices but can also be used on traditional multicore CPUs and even on manycore processors such as Intel Xeon Phi. Physical models include calorically perfect inert gas, single- and multi-temperature approaches for chemically reactive flows and an Euler–Euler model for gas-particle suspensions. Main details of the implementation are described. Shock capturing TVD and WENO schemes in general curvilinear coordinates are used for spatial approximation. Explicit, semi-implicit and fully implicit schemes are employed for advancing solution in time. The code is written in C++ with CUDA API and opensource libraries, such as MPI, zlib and VTK. A few examples of numerical simulations are briefly described to provide general idea of the numerical code capabilities. They include a supersonic flow past a wedge, a jet exhausting from a square nozzle, a heavy gas bubble descending in a lighter medium and a heterogeneous detonation in gas-particle suspension.

Motion analysis of armored vehicle suspension based on ADAMS

This paper takes the suspension of a 8×8 wheeled armored vehicle as the research object, uses Pro-E to model the armored vehicle, uses ADAMS simulation software to simulate the kinematics of the established suspension model, and analyzes the motion characteristics of the armored vehicle suspension from three aspects: positioning parameters, track width and suspension stiffness. It provides a reference for the optimal design of operational stability and ride comfort of wheeled armored vehicles.

Influence of bushing flexibility and its constitutive behavior on the performance of suspension system

We study the effect of strut top mount bushing flexibility and its constitutive law on the ride comfort performance of a quarter car suspension model. A fractional Kelvin–Voigt model has been employed to capture the viscoelastic behavior of the top mount bushings. To study the effectiveness of the suspension system, we have considered sinusoidal and standard (motion over bumps) road inputs. For the sinusoidal input, the frequency response function for both the traditional and fractional Kelvin–Voigt models has been obtained using the harmonic balance method. However, we have resorted to numerical simulations for the standard base inputs for which a reduced-order system of ODEs has approximated the fractional derivative term. Convergence of the reduced system of ODEs is established by comparing the numerical results for sinusoidal forcing with those obtained analytically. We find that the bushing modeled as a traditional Kelvin–Voigt element increases the response amplitude in the resonance zone, while for higher frequencies, the response reduces. Hence, the inclusion of bushing flexibility is equivalent to decreasing the damping in the suspension. These observations also remain valid for the fractional Kelvin–Voigt model, but the effect is less pronounced than in the traditional model. Ride comfort for standard road profile is studied in terms of performance indices which suggests that a fractional Kelvin–Voigt bushing improves the ride comfort. Accordingly, bushing flexibility with an appropriate constitutive law should be accounted in the design of a suspension system for ride comfort. • Effect of strut top mount bushing (STMB) flexibility on ride comfort is studied. • Fractional Kelvin–Voigt model is employed for the viscoelastic behavior of the STMB. • Studied the suspension system response on sinusoidal and standard road inputs. • Ride comfort has been studied in terms of transmissibility and performance indices. • We find that STMB flexibility improves ride comfort especially during transient loads.

Uncertainty Analysis of Suspension System Caused by Horizontal Misalignment and Its Suppression Method

The suspension system of the maglev train is a complex system, which is difficult to model accurately. The horizontal misalignment between the suspension magnet and the rail is one of the common uncertainty factors in the suspension system, which will affect the suspension performance. This article focuses on this problem. Firstly, the formula of suspension force considering horizontal misalignment is derived and the results of the formula and the FEA (Finite Element Analysis) simulation is consistent. Secondly, a suspension system model considering the horizontal misalignment is established for the first time, which can effectively describe the impact of the horizontal misalignment on the suspension system. Thirdly, a controller for the suspension system is designed by using the GIMC (Generalized Internal Model Control) paradigm and how the controller can effectively suppress the uncertainty caused by the horizontal misalignment is proved theoretically for the first time. Finally, the simulation and physical experiment verify that the proposed algorithm shows excellent performance and robustness in the system.

A new design of the seat suspension of the vehicles using the NSS: Part 2-Isolation performance of the NSS

Based on the dimensionless characteristics of the NSS added into the driver's seat suspension and its optimal ratios, a dynamic model of the driver's seat suspension equipped with the NSS is then built to evaluate the isolation performance of the NSS on improving the driver's ride comfort under the different excitations of the bumpy and random road surfaces. The reduction of the root mean square value of the displacement (zws) and acceleration (aws) of the driver's seat is the objective function for evaluating the isolation performance of the driver's seat suspension equipped with the NSS. The results indicate that with the optimal ratios of the 1 = 0.6, 2 = 1.2, and  = 0.6 of the NSS added into the driver's seat suspension, the driver's ride comfort is strongly reduced under both the vibration excitations of the bumpy and random functions. Particularly, the values of xws and aws of the driver's seat suspension added by the NSS are strongly reduced by 39.03% and 62.36% in comparison with the driver's seat suspension without the NSS. Therefore, the application of the NSS on the driver's seat suspension of the vehicles is not only simpler than that of the active or semi-active suspension systems in terms of structure, complexity, and cost but also can remarkably improve the driver's ride comfort.

Binocular visual pendulum angle detection and anti-swing control of quadrotor suspension system

Different from the pendulum angle detection by the optical capture system in the indoor environment, it is difficult to detect the pendulum angle of quadrotor suspension system in the outdoor environment. This paper presents a pendulum angle vision measurement scheme based on the model of the quadrotor suspension system, and applied to the quadrotor anti-swing control scheme with feedforward controller. The theoretical expression of the coordinate relationship between the pendulum angle and the spherical symbol is obtained by establishing the mathematical model of the quadrotor suspension system. The coordinates of spherical symbol fixed to the payload are detected by the visual algorithm. Simulations and experiments show that proposed method can accurately identify spherical symbol in sufficient light, and the maximum measurement error of [Formula: see text] angle is −0.024 rad and [Formula: see text] angle is −0.068 rad in the Gazebo simulation. Meanwhile, the results in MATLAB simulation indicate the anti-swing control scheme with feedforward controller can effectively restrain the payload’s swing.

Research on predictive coordinated control of ride comfort and road friendliness for heavy vehicle ISD suspension based on the hybrid-hook damping strategy

With the appearance of inerter, the ISD suspension composed of “Inerter-Spring-Damper” opens up a new direction for efficient coordination of ride comfort and road friendliness for heavy vehicles. In this paper, a reference model based on the hybrid-hook damping strategy is proposed, and the mechatronic inerter is used as an active suspension force generator in the actual controlled model. Then, the coordinated control of the vehicle ISD suspension model is realized by the model predictive control (MPC) approach. The test results show that, the RMS values of the body acceleration and dynamic tire load of the controllable ISD suspension is smaller than the traditional passive and passive ISD suspension under the sinusoidal road inputs. Under the random road input, compared with the traditional passive suspension, the controllable ISD suspension has improved the RMS value of the body acceleration by 26.61%, and the road damage coefficient has been improved by 20.13%. Experiments show that the controllable ISD suspension of heavy vehicles based on the hybrid-hook damping strategy has comprehensive improvement of vehicle ride comfort and road friendliness.

Vertical load distribution strategy of amphibious wheel-track vehicle using neural network and particle swarm optimization

Amphibious wheel-track vehicle (AWTV) can change the vertical load of the wheels and the tracks through the active hydro-pneumatic suspension system, which shows significant advantages in terms of maneuverability and road passing ability. However, AWTV is a strong nonlinear system. The irregularity of the road, and coupling characteristics between the vertical load of the wheel-tracks and the terrain will greatly affect the tractive efficiency of the whole vehicle. Therefore, how to effectively distribute the vertical load between the wheel and the track to improve the tractive efficiency of the whole vehicle is still a huge challenge. To address the above problems, based on the neural network (NN) and particle swarm optimization (PSO) algorithm, vertical load distribution strategy of the AWTV is proposed to improve its traction efficiency under different driving road in this paper. Firstly, the coupling dynamics model of AWTV with road and hydraulic system dynamics model of active suspension is established; Secondly, the wheel-track terrain model is built in EDEM-Recurdyn to collect data of vertical load and traction efficiency under the different soils and speeds, and the coupling function is obtained through NN; Then, the optimal vertical load of each axle is optimized through PSO; Finally, the feasibility and effectiveness of the strategy are verified by the simulation analysis under different road conditions and distribution strategies. The simulation and test results demonstrate that the proposed vertical load distribution strategy based on NN-PSO can effectively improve the traction performance of the AWTV in complex terrain environment, and have relatively superior control characteristics.

Two-Terminal Suspension Adaptive Control With Synchronous Compensation for Maglev Wind Turbine Yaw System

The article proposes an adaptive robust controller with synchronization compensation for the Maglev wind turbine yaw system to achieve stable nacelle suspension and pitching suppression. First, two-degree-of-freedom suspension model is constructed with consideration of magnetic coupling and pitching interference, and then deduces a two-terminal suspension control model based on the inverse system. Second, a nominal suspension controller is designed based on the composite error; and then an adaptive synchronization controller is proposed to adjust coupling parameters based on reconstructed synchronous function; an adaptive tracking controller is used to online update dominant control input parameters. The robust controller is to compensate for the influence of the approximation errors during the parameters convergence process. It is proved that the proposed strategy can guarantee the globally uniformly ultimately bounded of all signals, and suspension tracking error and synchronization error can converge to the desired smaller neighborhood of zero. Finally, simulation and experimental results show that the system with the proposed strategy has the faster dynamic response, smaller steady error and synchronization error, and stronger robustness than other two strategies.

Fuzzy robust non-fragile control for nonlinear active suspension systems with time varying actuator delay

The active suspension systems have attracted increasing attentions because of its advantages in improving automotive dynamic performance. This paper focuses on the fuzzy robust non-fragile [Formula: see text] control problem for the nonlinear active suspension system with the time-varying actuator delay and control uncertainty. Firstly, a Takagi-Sugeno fuzzy suspension model is established to describe the highly nonlinear components in the suspension system. Then, a series of linear matrix inequalities are derived based on a novel parameter Lyapunov function to guarantee the asymptotic stability of the suspension systems. Also, a fuzzy [Formula: see text] controller is derived for the proposed fuzzy suspension model with the parallel distributed compensation method. Thirdly, a co-design criterion is proposed to obtain the fuzzy controller with the time varying delay and control uncertainty simultaneously. Finally, both simulations and experiments are carried out to demonstrate the effectiveness and robustness of the proposed controller.

Multi-objective H2/H∞ control of uncertain active suspension systems with interval time-varying delay

The vehicle active suspension has been widely used as it could effectively improve the vehicle ride comfort. To solve the issues of actuator uncertainty and time delay existing in the active suspension system, a multi-objective non-fragile [Formula: see text] control algorithm is proposed in this work. First, to effectively describe the vehicle suspension dynamics, a quarter-car suspension model is constructed first in this study. Second, aiming at improving the ride quality and guarantee the hard constraints of the suspension system, a multi-objective H2/ H∞ performance index is proposed. Subsequently, the issues of external disturbances, actuator uncertainty and delay are considered in the design process of the suspension controller. Then, a multi-objective non-fragile control algorithm is proposed based on an effective Lyapunov functional. The control gain can be obtained by solving a convex optimization problem in terms of linear matrix inequalities. Finally, numerical simulations are implemented on MATLAB/Simulink platform to show the robustness and superiority of the proposed controller. Experiments are implemented on a quarter-car test rig to validate the practical performance of the designed controller.

Unified mean-field modeling of viscous short-fiber suspensions and solid short-fiber reinforced composites

Mean-field homogenization is an established and computationally efficient method estimating the effective linear elastic behavior of composites. In view of short-fiber reinforced materials, it is important to homogenize consistently during process simulation. This paper aims to comprehensively reflect and expand the basics of mean-field homogenization of anisotropic linear viscous properties and to show the parallelism to the anisotropic linear elastic properties. In particular, the Hill–Mandel condition, which is generally independent of a specific material behavior, is revisited in the context of boundary conditions for viscous suspensions. This study is limited to isothermal conditions, linear viscous and incompressible fiber suspensions and to linear elastic solid composites, both of which consisting of isotropic phases with phase-wise constant properties. In the context of homogenization of viscous properties, the fibers are considered as rigid bodies. Based on a chosen fiber orientation state, different mean-field models are compared with each other, all of which are formulated with respect to orientation averaging. Within a consistent mean-field modeling for both fluid suspensions and solid composites, all considered methods can be recommended to be applied for fiber volume fractions up to 10%. With respect to larger, industrial-relevant, fiber volume fractions up to 20%, the (two-step) Mori–Tanaka model and the lower Hashin–Shtrikman bound are well suited.

Ride performance of driver’s seat suspension system using various dynamics models

The research has proposed three isolation models of the negative-stiffness-element (NSE), the damping-element (DE), and the NSE embedded to the small mass (NSE-SM) that was connected with the seat suspension to ameliorate the ride comfort of the driver. A vibration model of the vehicle and seat built under the random and bumpy excitations has been used for evaluating the isolation performance of the NSE, DE, and NSE-SM. The effect of the NSE, DE, and NSE-SM’s dynamic parameters on their isolation performance is then evaluated via the root-mean-square values of the seat displacement ( z ws) and seat acceleration ( a ws). Based on the genetic algorithm, the NSE, DE, and NSE-SM’s dynamic parameters are optimized to fully reflect their isolation performance. The investigation result indicates that the driver’s ride comfort is slightly affected by the geometric dimension ratios of the NSE, DE, and NSE-SM, while the driver’s ride comfort is greatly affected by the damping and stiffness parameters; and the damping and stiffness ratios of the NSE, DE, and NSE-SM. With the optimized parameters of the NSE, DE, and NSE-SM, the simulation results under the different operating conditions of the vehicle show that the DE slightly improves the driver’s ride comfort. Conversely, both the NSE and NSE-SM greatly improve the driver’s ride comfort, especially the NSE-SM. Therefore, the model of the seat suspension embedded by the NSE-SM should be applied for improving the driver’s ride comfort.

Mechanism of Response of Alveolar Macrophages in Wistar Rats to the Composition of Atmospheric Suspensions

Atmospheric air quality is a crucial factor in the health of human populations. Suspended particulate matter (SPM) is one of the most dangerous components polluting urban air. The aim of the present article is to study the effect of model suspensions (MS) of SPM that are characteristic of the composition of atmospheric air at locations with various anthropogenic loads on redox processes in alveolar macrophages (AM). Atmospheric air sampling was carried out in the breathing zone according to the method developed by one of the authors. AM were isolated from bronchoalveolar lavage fluid of experimental animals. The MS of SPM were prepared in accordance with the actual air pollution: MS No. 1 corresponded to an area with a low man-made load, and MS No. 2 corresponded to an area with a high man-made load. Load tests with model suspensions were carried out for 2 days. Parameters of oxidant processes and antioxidant system (AOS) were determined in cells and culture media. The proportion of the influence of the qualitative and dispersed composition of MS and the indicator of intra-system tension were calculated based on correlation dependencies. The atmospheric air with a high man-made load was dominated by particles up to 10 µm, whereas air with an insignificant man-made load contained SPM of more than 10 µm in size. Unidirectional changes were observed due to an exposure to both model suspensions, but the most pronounced oxidative modifications of lipids, proteins and genetic structures were caused by the exposure to MS No. 2. When exposed to MS No. 1, the AOS maintained the redox balance at the physiological level, localizing the resulting destruction inside the cells. MS No. 2 caused the redox balance to shift towards oxidants, potentiating the generalization of the destruction process. An increase in the content or a longer stress-inducing effect of PM2.5 causes a depletion in the reserve capacity of the AOS and the transition of destruction processes to the systemic level, which contributes to the development of the preconditions for environmentally dependent pathology.

Magnetoresponsive Functionalized Nanocomposite Aggregation Kinetics and Chain Formation at the Targeted Site during Magnetic Targeting

Drug therapy for vascular disease has been promoted to inhibit angiogenesis in atherosclerotic plaques and prevent restenosis following surgical intervention. This paper investigates the arterial depositions and distribution of PEG-functionalized magnetic nanocomposite clusters (PEG_MNCs) following local delivery in a stented artery model in a uniform magnetic field produced by a regionally positioned external permanent magnet; also, the PEG_MNCs aggregation or chain formation in and around the implanted stent. The central concept is to employ one external permanent magnet system, which produces enough magnetic field to magnetize and guide the magnetic nanoclusters in the stented artery region. At room temperature (25 °C), optical microscopy of the suspension model’s aggregation process was carried out in the external magnetic field. According to the optical microscopy pictures, the PEG_MNC particles form long linear aggregates due to dipolar magnetic interactions when there is an external magnetic field. During magnetic particle targeting, 20 mL of the model suspensions are injected (at a constant flow rate of 39.6 mL/min for the period of 30 s) by the syringe pump in the mean flow (flow velocity is Um = 0.25 m/s, corresponding to the Reynolds number of Re = 232) into the stented artery model. The PEG_MNC clusters are attracted by the magnetic forces (generated by the permanent external magnet) and captured around the stent struts and the bottom artery wall before and inside the implanted stent. The colloidal interaction among the MNC clusters was investigated by calculating the electrostatic repulsion, van der Waals and magnetic dipole-dipole energies. The current work offers essential details about PEG_MNCs aggregation and chain structure development in the presence of an external magnetic field and the process underlying this structure formation.

Bone-Targeting Nanoparticles of a Dendritic (Aspartic acid)3-Functionalized PEG-PLGA Biopolymer Encapsulating Simvastatin for the Treatment of Osteoporosis in Rat Models.

Simvastatin (SIM) is a lipid-lowering drug that also promotes bone formation, but its high liver specificity may cause muscle damage, and the low solubility of lipophilic drugs limits the systemic administration of SIM, especially in osteoporosis (OP) studies. In this study, we utilized the bone-targeting moiety of dendritic oligopeptides consisting of three aspartic acid moieties (dAsp3) and amphiphilic polymers (poly(ethylene glycol)-block-poly(lactic-co-glycolic acid); PEG-PLGA) to create dAsp3-PEG-PLGA (APP) nanoparticles (NPs), which can carry SIM to treat OP. An in vivo imaging system showed that gold nanocluster (GNC)-PLGA/APP NPs had a significantly higher accumulation rate in representative bone tissues. In vivo experiments comparing low-dose SIM treatment (0.25 mg/kg per time, 2 times per week) showed that bone-targeting SIM/APP NPs could increase the bone formation effect compared with non-bone-targeting SIM/PP NPs in a local bone loss of hindlimb suspension (disuse) model, but did not demonstrate good bone formation in a postmenopausal (ovariectomized) model of systemic bone loss. The APP NPs could effectively target high mineral levels in bone tissue and were expected to reduce side effects in other organs affected by SIM. However, in vivo OP model testing showed that the same lower dose could not be used to treat different types of OP.