Random Road Profile Research Articles

AN INVESTIGATION OF A TWO-STAGE ASYMMETRIC DAMPER’ EFFECT ON THE RIDE COMFORT OF AN INNER-CITY BUS BY USING 3-DOFS VEHICLE MODEL SUBJECTED TO RANDOM ROAD PROFILES

The effect of the asymmetric damper on the vertical acceleration of the driver’s body, suspension deflection and tire dynamic load were studied thoroughly in order to provide suggestions for choosing damping parameters while building a bus’s suspension system. The vehicle model with three DOFs exposed to random road profiles was employed to investigate the dynamic responses for both two cases of linear symmetric and two-stage asymmetric dampers. The investigation was carried out in the time domain by simulation, then the root-mean-square of oscillatory parameters was calculated and examined by using a program made in the MATLAB software. The results of the analysis show that a two-stage asymmetric damper ensures good oscillatory comfort of the driver but provides less handling stability of the bus when compared to a linear symmetric one.

Prediction of the driver’s head acceleration and vibration isolation performance of the seating suspension system using the time and frequency domain modeling

Long-time exposure to low-frequency vibration will negatively impact human health.A rapid biodynamic system modeling method has been proposed to study the human body’s response to the low-frequency vibration excitation in the whole vehicle environment. The sensitivity of design parameters of the seating suspension system to the vibration isolation performance will be studied. The dynamic model consists of a lumped parameter mass-spring-dashpot model of seven degrees of freedom (7DOF) and used for the prediction of the head acceleration in the time domain and peak transmissibility ratio in the frequency domain under a sinusoidal wave excitation and random road profile excitations of different road classes and vehicle speeds. A calculation formula has been established to predict the seat effective amplitude transmissibility (SEAT) from the transmissibility ratios and frequency weighting function of the ISO 8606, while the transmissibility ratios can be calculated from the frequency response analysis of the seven degrees of freedom system dynamic equations. The simulation results in the frequency domain have been verified by those in the time domain for the linear system assumption. The change trends of the driver’s head acceleration, SEAT value, and peak transmissibility ratio from the driver’s head to the seat base with respect to the stiffness and damping coefficients of the seat and cushion have been compared with and verified by one another.It is proved that in the vehicle system, individually, reducing the individual stiffness and damping coefficients of the seat structure, reducing the individual seat cushion stiffness, and increasing the individual seat cushion damping coefficient one by one will be able to reduce the driver’s head acceleration, peak transmissibility ratio, and SEAT value from the head to seat base, and improve the ride comfort. Simultaneously reducing the stiffness and damping coefficients of the seat and cushion will be able to reduce the driver’s head acceleration, peak transmissibility ratio, and SEAT value from the head to seat base and improve the ride comfort. The reduction effect of the driver’s head acceleration is more substantial under the Class E road profile of a large profile roughness than that under the other road classes.

Vibration Analysis of a Bus’s Air Spring Suspension Subjected to Random Road Profile

Vehicle dynamics model in type of 1/4 is used for vibration analysis under the effect of random road profile with different grades. The mathematical model to describe the used random road profile is able to change the type of investigated road grades by selecting the corresponding power spectral density parameter of the road grade according to the ISO 8608 standard. Random road profile is ivestigated in the range of frequency domain from 0 to 50 (Hz). The air spring stiffness and the damping coefficience are determined on the basis of reference to the practical vehicle. The variation of relative displacement amplitude of the suspension in the range of investigation domain is small, the air spring stiffness used in the calculation is constant. The obtained results corresponding to different grades of road surface roughness including displacement and acceleration parameters. Relative displacement is a parameter that aims to verify the ability to ensure safe working of the suspension, namely rattle spacing. Acceleration is used to evaluate the vehicle's comfort. Calculation results are analyzed as the basis for evaluating the influence of the air spring stiffness and road surface conditions on the comfort of the vehicle, as the basis for changing the air spring stiffness in accordance with adjusting the pressure of it according to the type of road profile quality.

Modelling and simulation of active and passive seat suspensions for vibration attenuation of vehicle occupants

Literature on biodynamic modelling of the occupant in a vehicle associates riders’ comfort with human-seat interaction forces and vibration attenuation capabilities of the suspension system. Though the superiority of active suspension systems over passive ones is well established in literature, quantification of this superiority by using the best possible passive suspension system has not been reported. This work attempts to do this. It integrates a nonlinear cushion seat contact force model and a 12 degrees of freedom two-dimensional seated human body model supported by an inclined backrest with a full vehicle model through the seat suspension system. The passive and active proportional integral derivative suspension system parameters are obtained by simultaneously minimizing the seat effective amplitude transmissibility, cushion contact force and head motion using a multi-objective genetic algorithm in MATLAB-SIMULINK co-simulation. The time responses of cushion contact force, head vertical and fore-aft motion are studied for two road profiles—random and bump. Comparative analyses were also done with regard to internal forces, absorbed power and the effect on vehicle chassis. Human body response to different grades of road roughness and vehicle speeds were investigated. The results establish the clear superiority of the active system in all aspects with rise in suspension travel and acceleration of vehicle chassis in the vertical direction for a random road profile. A parameter sensitivity analysis allowed us to identify spring stiffness as the component which needs greatest care during fabrication.

Simulation of processes in machines using orthogonal meshes

The paper presents an experience of using orthogonal hexahedral meshes for simulation of different processes in machine-building products. Stress state of the details of suspension of a cargo vehicle during the movement on random road profile was simulated. Orthogonal hexahedral meshes for lower suspension levers and housing and piston rod of shock adsorber were used. Thermal state of the elements of drive axle and its housing during the movement of a cargo vehicle with constant speed was calculated using hexahedral orthogonal meshes for details and inner volume of housing of the drive axle. Lubrication fluid circulation in the reducer of a cargo vehicle was modelled. Orthogonal mesh for inner volume of the reducer was used to calculate the parameters of lubrication fluid circulation.

Dynamic analysis of semi-active MR suspension system considering response time and damping force curve

To obtain a good ride quality and smooth car body motion, many studies have focused on the damper. Passive dampers are unable to respond actively to changes in the environment; hence many studies are being conducted on semi-active dampers that use magnetorheological (MR) fluids. As the damping characteristics of the MR damper, such as the response time, control gain, and gradient of the damping force curve, can significantly affect the control performance of the vehicle, the damping characteristics of the MR damper should be carefully considered. Accordingly, in this study, we developed a method for selecting the damping characteristics of an MR damper for specific vehicle types and analyze the relation between the dynamic characteristics of MR damper and driving performances. To achieve this objective, we demonstrated that the damping characteristics can be tuned according to the additional flow path, groove, and core material. To confirm the enhancement of the ride quality, vibration control performance, and steering stability, the skyhook controller was considered. Since we obtained the suitable damping characteristics that met the requirements under random road profiles and bumpy roads, the realization of these characteristics will enable us to satisfy the driving requirements.

Optimal Selection for an Air Suspension System on Buses Through an Unique High Level Parameter in Genetic Algorithms

Air suspension systems are being widely used on ground vehicles in general and buses in particular. The element that makes the superiority of this system is air spring. This paper introduces the application of genetic algorithms method to optimize the parameters of the air spring element. A full model of a bus using air suspension system with air spring element, which is modeled based on the Gensys model. From the real experiments, the bounds of seven optimized parameters of the air spring is determined. In which, by using a single α value, it is possible to determine the optimal parameters according to each desired criteria between the road safety and the ride comfort. Optimal results are verified in the time domain simulations with random road profile according to the ISO standard 8608. The results show that by using the optimal parameters of the air spring when α =0.5, the ride comfort is improved about 15% while the road safety is still guaranteed.

Optimization of Multiple Tuned Mass Dampers for Road Bridges Taking into Account Bridge‐Vehicle Interaction, Random Pavement Roughness, and Uncertainties

Road bridge designs are based on technical standards, which, to date, consider dynamic loading as equivalent static loads. Additionally, the few engineers who perform a dynamic analysis typically do not consider the effects of bridge‐vehicle interaction and also simplify the road’s irregularity profile. Moreover, often, even when a simplified dynamic analysis is carried out and shows that there will be a high dynamic amplification factor (DAF), designers prefer to solve this problem by adopting high safety factors and thereby oversizing the bridge, rather than using energy dissipation devices that would allow reducing the amplitude of vibration. In this context, the present work proposes a complete methodology to minimize the dynamic response of road bridges by optimizing multiple tuned mass dampers (MTMD), taking into account the bridge‐vehicle interaction, the random profile of pavement irregularities, and the uncertainties present in the coupled system and in the excitation. For illustrative purposes, the coupled vibration problem of a regular truck traveling on a random road profile over a typical Brazilian bridge is analyzed. Three different scenarios for the MTMD are considered. The proposed optimization problem is solved by employing the Whale Optimization Algorithm (WOA). The results showed the excellent ability of the proposed methodology, reducing the bridge’s DAF to acceptable values for all analyzed cases, considering or not the uncertainties present in the system. Furthermore, the results obtained by the proposed methodology are compared with results obtained using classical tuned mass damper (TMD) design methods, showing the best performance of the proposed optimization method. Thus, the proposed method can be employed to optimize MTMD, improving bridge design.

Study the dynamic behaviour of seven DOF of full car model with semi-active suspension system

This paper presents an investigation on the ride comfort and road-holding performance of a vehicle equipped with the semi-active suspension system. The full car semi-active suspension model with 7 degrees of freedom (7 DOF) system is adopted for the study and a fuzzy-logic control strategy is considered for minimising the effect of road disturbance on vehicle performance. The responses of a vehicle have been analysed under the Indian average random road profile (ISO8608) against the conventional passive suspension system. The performance of the semi-active suspension system is evaluated by heave, roll and pitch acceleration of the vehicle body around its centre of gravity. The performance of a vehicle with the semi-active suspension system has been compared with the response conventional passive suspension system. The result specifies that, the semi-active suspension system with a fuzzy-logic controller reduces around 43% of vibration amplitude at the resonance frequency of vehicle than the passive suspension system.

Active and Passive Suspension System Performance under Random Road Profile Excitations

Passive suspensions are designed to satisfy the conflicting criteria of riding comfort and vehicle handling. An active suspension system attempts to overcome these compromises to provide the best performance for vehicle control. Different types of mathematical models have been used to study the suspension system of a vehicle. The quarter vehicle model is used for initial investigation. Later, the half vehicle and full vehicle models are used for the study, which is closer to the actual model of a vehicle suspension. In this paper, the behavior of a suspension system is analyzed using the full vehicle model. In the current work, the dynamic equation and their state-space formulation are presented for the full vehicle model to understand the system prior to the controller design. The open-loop response of the full vehicle suspension system, when subjected to various road excitations, is also studied. The procedure of modeling a SIMULINK model for passive suspensions system is discussed in detail. Design of the simple Proportional Integral Derivative (PID) feedback and feed-forward controller is presented for the active suspension system using transfer functions. Closed-loop transfer functions are also derived and their responses are plotted. To analyze the rollover behavior simulation for cornering is also performed in the current study.

Ride Comfort-Road Holding Trade-off Improvement of Full Vehicle Active Suspension System by Interval Type-2 Fuzzy Control

This paper presents a hybrid fuzzy controller structure to improve ride comfort-road holding trade-off characteristics of a full vehicle active suspension system. The controller includes two interval type-2 fuzzy logic controllers, optimized for ride comfort and road holding, for each tire. Type C random road profiles according to ISO 8608 are applied to each tire in the model and ride index, road holding, crest factor, and RMS acceleration values are evaluated. Stability of the overall closed loop system is presented by phase plane analysis. The simulation results reveal that simultaneous improvement of ride index and road holding can be made possible with the proposed controller.

Design of Hydraulic Exciter Using Nonstandard Backstepping with Integral Sliding Mode

The hydraulic system plays an important role in the design of many mechanical devices due to its high power to weight ratio. In this work, a theoretical study of a hydraulic stimulator was performed to conduct suspension tests in a quarter car in the laboratory. Due to high nonlinearity in the hydraulic systems, a robust controller based upon integral sliding mode (ISMC) with nonstandard backstepping was used to perform the tracking process of the hydraulic actuator to the required road profiles. The controller design divided into two parts: the first part deals with the generation of the ideal control force which satisfied all the tracking requirements by using ISMC. The second part of the controller is the replacing of the ideal control force with the actual hydraulic force with all parameters by using nonstandard backstepping control. The effectiveness of the exciter control system was performed by using two road profiles i.e. Bump road profile and random road profile.

Simulation study on ride comfort enhancement for a heavy duty vehicle with fractional order sliding mode controller

The main goal of vehicle active suspension system is to upgrade the ride quality and stability of heavy duty vehicle (HDV) regardless of road surface. The mathematical modelling of HDV with two degrees of freedom is developed and simulated in MATLAB/Simulink environment. The simple and effective control techniques such as proportional integral and derivative (PID) controller, sliding mode controller (SMC) and fractional order sliding mode controller (FOSMC) are designed to detach the vibration from the passenger under step, sinusoidal and random road profile. Literature reveals that the FOSMC can eliminate steady state error and chattering effect unlike SMC and PID. The dynamic analysis of designed controllers is examined in terms of time domain, frequency domain and ride comfort analysis as per ISO 2631. The stability of SMC and FOSMC is confirmed by Lyapunouv stability for three different road profiles. The FOSMC shows satisfactory simulation results than SMC, PID and passive suspension system in reducing suspension deflection and body acceleration of HDV to upgrade the ride quality. Further, the efficacy of proposed FOSMC is proved by comparing the simulation results against existing results of PID controller.

Numerical analysis and performance enhancement of active suspension system using bat optimization

The predominant role of an active suspension system in Heavy Duty Vehicles (HDV) is to minimize vibrations caused by road disturbances. In this study, linear two degrees of freedom HDV model is simulated in a MATLAB/Simulink environment. The conventional Proportional Integral and Derivative (PID) controller has little effect on vibration suppression. To reduce the effect of vibration in the HDV, the PID controller’s output parameters are optimized by bat and Grey Wolf optimization techniques. The proposed optimization techniques have the potential to enrich the ride comfort of the passenger when the HDV is travelling over different types of road surfaces such as step, sinusoidal and ISO 8608 random road profiles. The ISO 2631 standard is used to examine the health criterion and ride comfort of the passengers. Further, comparative time domain and power spectrum density analyses are carried out for the PID controller and proposed optimization techniques. The simulation results confirm that the proposed bat tuned PID is more efficient in all aspects and significantly improves the ride comfort for the three different road profiles.

Back-iron design-based electromagnetic regenerative tuned mass damper

Implementation of tuned mass dampers is the commonly used approach to avoid excessive vibrations in civil engineering. However, due to the absence of the compact dimension, there are still no practical applications of the tuned mass dampers in automotive industry. Meanwhile, recent investigations showed the benefit of utilizing a tuned mass damper in a vehicle suspension in terms of driving comfort and road holding. Thus, the current investigation aimed to explore a novel compact dimension tuned mass damper, which can provide both sufficient vibration mitigation and energy harvesting. This paper presents a prototype of a back-iron-based design of an electromagnetic regenerative tuned mass damper. The mathematical model of the tuned mass damper system was developed and has been validated by the experimental results of the tuned mass damper prototype implemented in a protected mass test-bench. The indicated results concluded that the attenuation performance dramatically deteriorated under random excitations and a reduction in the root-mean-square acceleration of 18% is concluded compared to the case with undamped tuned mass damper. Under harmonic excitations, the designed tuned mass damper prototype is able to reduce the peak acceleration value of the protected structure by 79%. According to the experimental results, the designed tuned mass damper prototype revealed a peak regenerative power of 0.76 W under a harmonic excitation of 8.1 Hz frequency [Formula: see text]m amplitude. Given the simulated random road profiles from C to E, the back-iron electromagnetic tuned mass damper indicated that root-mean-square harvested power from 0.6 to 6.4 W, respectively.

Response time of magnetorheological dampers to current inputs in a semi-active suspension system: Modeling, control and sensitivity analysis

A new magnetorheological (MR) damper has been recently developed that delivers a very fast response to the input current (or magnetic field). This study investigates the effect of the MR-damper response time on the vibration control of a full-car semi-active suspension system subjected to parameter uncertainties. After briefly reviewing the response-time characteristics of the fast-response MR damper, a full-car suspension model with seven degrees of freedom (DOF) is derived by considering the time constant of the actuator. Subsequently, a robust sliding mode controller is formulated for achieving effective vibration control of the suspension system for three different motions: heave, pitch, and roll. For the synthesis of the controller, the sprung mass is considered the uncertain parameter, and the stability of the overall control system is proved via Lyapunov stability. By evaluating the performance at a random road profile, it is shown that both ride comfort and road holding (steering stability) can be enhanced by utilizing the fast-response MR damper. In addition, to analyze the control results, the nonlinear suspension model is linearized. Using the linearized model, the state outputs from the road input are observed, and the sensitivities of the closed loop feedback system considering response time of MR dampers are analyzed in the Nyquist domain.

Design of Fuzzy Super Twisting Sliding Mode Control Scheme for Unknown Full Vehicle Active Suspension Systems Using an Artificial Bee Colony Optimization Algorithm

AbstractThis article proposes a new intelligent control scheme that uses the Fuzzy Super Twisting Sliding Mode Concept (FSTSMC) and PID controller tuned with the Artificial Bee Colony (ABC) algorithm to control a full vehicle active suspension system with new convergence proof. Suspension systems are utilized to provide vehicle safety and improve comfortable driving. The effects of road roughness transmitted by tires to the vehicle body can be reduced by using suspension systems. In this work super twisting sliding mode is combined with a fuzzy system to design a robust control method. The super twisting sliding mode concept is utilized to limit and minimize the chattering problem and the fuzzy system is used for estimating the unknown parameters and uncertainty in the suspension system components (spring, damper, and actuator). The advantage of such combination is that it can handle the uncertainties and nonlinearities efficiently. The PID controller is used to create the required force to be produced by the actuator. The proposed control scheme consists of four similar sub control schemes, one for each of the four corners of the vehicle. All parameters in the sub control schemes are optimized using the ABC algorithm. The designed control system is applied for a full vehicle model with 8 degrees of freedom. Simulation results show large reduction in the vibration of the vehicle body when passing on disturbance and also show good robustness properties when tested for different road conditions. Passive and active suspension systems using sliding modecontrol (SMC) and the proposed FSTSMC are compared to test the efficiency and the ability of the proposed control scheme to achieve safe and comfortable driving for a random road profile.

Fatigue life study of suspension ball joints on the basis of ride quality

The MacPherson quarter car model was used to determine fatigue life of a suspension ball joint using a non-conventional approach which combined rigid body dynamics with finite element (FE) analysis. In this research, a quarter car model was subjected to International Standards Organization (ISO) random road profile with a pothole and a speed bump in order to obtain the ride quality and the reaction forces occurring at the ball joint. After classifying three ride qualities, another simulation was conducted on this model to study the stress distributions, in which the ball joint and its socket were treated as flexible bodies. Finally, based on the results of the FE analysis, fatigue life of the joint was measured for each ride quality. Based on the findings, it was concluded that a good ride quality has an adverse effect on the fatigue life of the ball joint component. ANSYS Workbench and CATIA V5 were used for modelling and simulation.

Fatigue life study of suspension ball joints on the basis of ride quality

The MacPherson quarter car model was used to determine fatigue life of a suspension ball joint using a non-conventional approach which combined rigid body dynamics with finite element (FE) analysis. In this research, a quarter car model was subjected to International Standards Organization (ISO) random road profile with a pothole and a speed bump in order to obtain the ride quality and the reaction forces occurring at the ball joint. After classifying three ride qualities, another simulation was conducted on this model to study the stress distributions, in which the ball joint and its socket were treated as flexible bodies. Finally, based on the results of the FE analysis, fatigue life of the joint was measured for each ride quality. Based on the findings, it was concluded that a good ride quality has an adverse effect on the fatigue life of the ball joint component. ANSYS Workbench and CATIA V5 were used for modelling and simulation.

GPU based Stochastic Parameterized NMPC scheme for Control of Semi-Active Suspension System for Half Car Vehicle

Control of complex systems with inherent randomness in process dynamics poses a serious concern for control engineers, especially in situations where performance and constraint satisfaction are highly demanded. In this paper, we propose a real time (RT) scenario based stochastic parameterized NMPC (SS-pNMPC) scheme for control of semi-active (SA) system for a half car vehicle. The method utilizes graphic processing unit (GPU) to generate several RT scenarios of the random road profile for each parameterized input and through Monte-Carlo (MC) simulations, the expected objective function along with a probabilistic constraint violation certificate are numerically obtained. The optimal input is elicited by finding the input either with minimum expected objective or with the lowest probabilistic constraint violation certificate. The method was implemented on NVIDIA Jetson embedded boards and also, tested in MATLAB/Simulink environment for different ISO road profiles and the simulation results exhibits better performance of the proposed method in comparison to passive systems.