Vehicle Body Vibration Research Articles

Passive Skyhook Suspension Reduction for Improvement of Ride Comfort in an Off-Road Vehicle

With the use of Routh stability criterion and Pade approximation technique to simplify the passive skyhook damping suspension system, a full-car model involving the reduced-order ISD suspension was established for the analysis of ride comfort. The genetic algorithm of unified objective function was applied for the optimization of structural parameters. Comparative analysis of the system performance was conducted among the conventional passive suspension, the passive skyhook damping suspension and the reduced-order ISD suspension. The results show that the root-mean-square value of body acceleration, tire dynamic load and suspension working space of the reduced-order ISD suspension are close to those of the passive skyhook damping suspension and the main performance can be achieved. It illustrates that the overall performance of the reduced-order ISD suspension can be close to the passive skyhook damping suspension and the research theoretically verified the effectiveness of the reduced-order ISD suspension. Furthermore, a integrated inerter device with inerter and damper connected in series is developed, which is then arranged in the front and rear suspension of an off-road vehicle for road test. As a result of this paper, it was demonstrated that, the reduced-order ISD suspension can suppress the vertical, pitch and roll vibration of vehicle body.

Fundamental study for extracting high contributing vehicle body vibration modes to road noise utilizing operational TPA

Fundamental study for extracting high contributing vehicle body vibration modes to road noise utilizing operational TPA

Optimization of damping in the passive automotive suspension system with using two quarter-car models

The paper presents the optimization of damping in the passive suspension system of a motor vehicle moving rectilinearly with a constant speed on a road with rough surface of random irregularities, described according to the ISO classification. Two quarter-car 2DoF models, linear and non-linear, were used; in the latter, nonlinearities of spring characteristics of the suspension system and pneumatic tyres, sliding friction in the suspension system, and wheel lift-off were taken into account. The smoothing properties of vehicle tyres were represented in both models. The calculations were carried out for three roads of different quality, with simulating four vehicle speeds. Statistical measures of vertical vehicle body vibrations and of changes in the vertical tyre/road contact force were used as the criteria of system optimization and model comparison. The design suspension displacement limit was also taken into account. The optimum suspension damping coefficient was determined and the impact of undesirable sliding friction in the suspension system on the calculation results was estimated. The results obtained make it possible to evaluate the impact of the structure and complexity of the model used on the results of the optimization.

Neural Network based Vibration Control for Vehicle Active Suspension System

This paper presents a novel Neural Network (NN) based vibration control of a Vehicle Active Suspension System (VASS) when subjected to road disturbance for enhancing the travelling comfort to the passengers. The simulation for the vibration control of VASS with Proportional Integral and Derivative (PID) controller is used for training the NN. The nonlinearities of the system parameters can be effectively handled by the NN and also it can deal with unfocused data by considering the prejudiced phenomena such as logical reasoning and perception beyond its domain. The idea of this work is to design, simulate and compare the performance of NN based VASS with that of the uncontrolled suspension system (passive) and the VASS controlled with PID controller. The Root Mean Square (RMS) value of body acceleration as the performance index for genetic optimization, the simulation is carried out using MATLAB/SIMULINK software. Simulation results such as sprung mass displacement, body acceleration, suspension deflection, tyre deflection and Power Spectral Density (PSD) of body acceleration shows the effectiveness of NN in suppression of the vibration of vehicle body compared to passive system, PID based VASS and optimized PID controller.

Vibration analysis for vehicle with Vacuum Packed Particles suspension

The paper concerns an effect of the damping force controlling a vehicle suspension system. The investigated vehicle suspension system consists of innovatory Vacuum Packed Particles controllable dampers which allow controlling the vehicle body vibration. The main objective of performed and presented in the paper studies is to determine properties of the Vacuum Packed Particles (VPP) damper and propose a preliminary control strategy. The control in the vehicle suspension system can be realized by controlling the underpressure resulting in various jamming mechanisms in the granular core. Some algorithms of vibration control are also proposed and discussed.

Fuzzy Controller for Semi-Active Automobile Suspension System under Random Profiled Road Input

The suspension system is one of the most important parts of the automobile. The suspension system has an important influence on the ride comfort and maneuverable stability of the automobile. As structure parameters of traditional passive suspension cannot adaptively change with external conditions, the improvement of dynamic performance is difficult. Tow-DOF and four-DOF suspension of vehicle model is set up in this paper. Under random profiled road input simulated by using Runge-Kutta method, the control laws of fuzzy controller are adjusted by using different weight coefficients and use Matlab software to simulate the performances. Then, the results are compared and the performances are analyzed between passive suspension and semi-active suspension. The simulation results show the semi-active suspension is more effective for decreasing the vibration of vehicle body than the passive suspension, and designed fuzzy controller is effective for controlling the active controller of the semi-active suspension.

Performance of Measuring Vibration of MEMS Sensor

Recently, many studies on application of farming support and agricultural work management system using information and communication technology to management efficiency of agriculture have been progressed and agricultural machinery of high efficiency and high utilization have also been required. This has brought about consideration of the construction of such measuring system as being important that could identify operating information of agricultural vehicle including safety of vehicle body. Rudimentary operating information of agricultural packaging machinery is exactly about the characteristics of motion of vehicle. In order to identify them, 6 degrees of freedom components of vibration acceleration are required. Previous studies on measuring the vibration of vehicle body of 6 degrees of freedom components of vehicle have been through measuring of translational acceleration of translational accelerometer and rotational acceleration of gyro. However, this method has problems in that measuring system is so large and costly that it could not be regularly used in measuring vibration acceleration and identifying operating conditions of vehicle body (Choe, Jung Seob and E. Inoue, 2001; Inoue E. et al., 1990). Therefore, this study aims to examine the usefulness of MEMS (Micro Electro Mechanical System) sensor, a compact and affordable sensor which has recently received attention, for measuring vibration of agricultural vehicle by obtaining serial data of vibration acceleration using an MEMS sensor and translational accelerometer and thereby calculating and comparing RMS (Root Mean Square) and PSD (Power Spectral Density) as a step before construction of measuring system which can always identify operating conditions of agricultural packaging machinery.

H∞ control of railway vehicle suspension with MR damper using scaled roller rig

In this paper, a magneto-rheological (MR) damper was applied to the secondary suspension to reduce the vibration of a car body. The control performance of the MR damper was verified by numerical analysis with a 1/5 scale railway vehicle model in accordance with the similarity law. The analysis results were then validated in tests. In particular, the objective of the study was to understand how the control performance affected the dynamic characteristics of a railway vehicle and to systematically analyze the relationship between control performance and dynamic characteristics depending on various running speeds. To achieve this, experimental results for the dynamic characteristics of the scaled MR damper designed for the 1/5 scale railway vehicle model were applied to the railway vehicle model. The H∞ control method was applied to the controller. The means of designing the railway vehicle body vibration controller and the effectiveness of its results were studied.

Vibration control of vehicle active suspension system using novel fuzzy logic controller

In this paper, the vibration control of vehicle active suspension system (VASS) using an intelligent type-2 fuzzy logic controller (T2FLC) is projected. In a vehicle, the active suspension plays an important role in isolating the passengers and the vehicle body from the road roughness. Initially, a non-intelligent-based proportional, integral and derivative controller (PIDC) and then an intelligent-based type-1 fuzzy logic controller (T1FLC) have been designed to ensure travelling and ride comfort of a road vehicle. The fuzzy logic is one of the efficient ways that implements engineering heuristics into control action. With the selected fuzzy rules, the PIDC shows better performance than the T1FLC. Secondly, T2FLC which is proved to be efficient than the T1FLC and that can handle uncertainties to a greater extent is used for control purpose in a VASS. Using MATLAB/SIMULINK, the simulation is performed by considering the root mean square (RMS) value of body acceleration as the performance index. Simulation results such as sprung mass displacement, body acceleration, suspension deflection, tyre deflection and power spectral density (PSD) show the effectiveness of the T2FLC over T1FLC, PIDC and passive system in suppression of the vibration of vehicle body.

Research of Self-Adjust Compromise Control Strategy about Comfort and Stability of Quarter Vehicle

On the basis of the MRD 1/4 vehicle model, and combined with the thought of mixed control of skyhook damper and ground-hook damper, a hybrid semi-active control strategy that the coordinated parameters are adjusted automatically according to the vehicle speed is put forward in order to meet the requirements of the riding comfort and the adhesive performance under different working conditions. Based on the reconfigured standard Grade B and C road excitation signals, simulation researches on vertical vibration of vehicle body, dynamic deflection of vehicle suspension and dynamic loads of tires are carried on respectively at the speed of 10m/s, 20m/s and 30m/s. As shown in the results of the simulations, compared with passive suspension the vibration is decreased about 10 percent, the dynamic loads of tires maintain the same level on the whole, and the suspension deflection had increased in certain degree. This demonstrates that the devised control strategy of semi-active suspension can effectively improve the riding comfort and the adhesive performance of vehicles at various speeds.

Investigation on Technology of Automobile Vibration and Noise Reduction Based on Body-In-White Structure

The automotive body system is not only a source for directly radiating noise into the vehicle interior space, but also a key component for transmitting various vibrations and noise. The optimization of the modes for body-in-white has significant meanings for improving the reliability and NVH (Noise, Vibration and Harshness) performance of the whole vehicle. Based on the current situation that there is more severe interior vibration and noise problem occurring in driving for a light passenger vehicle, a hybrid modal analysis method combined with experiment and simulation methods is applied to investigate the vibration and noise characteristics of the whole vehicle body. By performing such modal analysis, the modal frequencies of the auto-body are improved effectively by strengthening the vibration sensitive regions in the body structure. The experiment for measuring interior vibration and noise levels under cruise condition is conducted to validate that the structural optimization for body-in-white has significant contribution for improving the whole vehicle NVH performance.

Vibrations control of light rail transportation vehicle via PID type fuzzy controller using parameters adaptive method

In this study, a conventional PID type fuzzy controller and parameter adaptive fuzzy controller are designed to control vibrations actively of a light rail transport vehicle which modeled as 6 degree-of-freedom system and compared performances of these two controllers. Rail vehicle model consists of a passenger seat and its suspension system, vehicle body, bogie, primary and secondary suspensions and wheels. The similarity between mathematical model and real system is shown by comparing uncontrolled simulation results and vibration measurements. For carrying a comfortable travel, rail vehicle body and passenger seat vibrations are minimized by adding a controller between rail vehicle body and bogie in the model of this system. To control vibrations actively, a PID type fuzzy controller which is obtained by combining fuzzy PI and fuzzy PD controllers is preferred because of its robust character and superior performance. The PID type fuzzy controller using parameter adaptive method is designed by tuning the parameters online. Also, obtaining higher performance from this controller is studied.

Analysis of Vehicles Dynamic Properties from the Point of View of Passenger Comfort

The passenger ride comfort can be assessed via the indexes of comfort i.e. via the indirect method in accordance with the European standard ENV 12299: 1999 or 2006. This method is based on the values of accelerations knowledge in the analysed places of vehicle body. The signal of accelerations is filtered and weighted with functions that take into account the sensitivity of human body to the vehicle body vibrations in reference directions. The signal is statistically assessed and the ride comfort indexes for floor, sitting or standing positions are evaluated. The accelerations coming into the assessment of ride comfort indexes can be obtained from measurements or as results of a computer simulation. The paper deals with the accelerations analysis and their influence on the final comfort index.

Self-tuning vibration absorber system and method of absorbing varyng frequency vehicle vibrations

A system and method for absorbing vehicle body vibrations is described. The mechanical self-tuning vibration absorber system is utilized to absorb a body vibration with a varying frequency. In a particular application the absorber system provides for absorbing varying frequency vibrations of a helicopter aircraft body. The vibration absorber system utilizes asymmetrical damping to tune the resonant frequency of the system.

Fuzzy logic control of vehicle suspensions with dry friction nonlinearity

We design and investigate the performance of fuzzy logic-controlled (FLC) active suspensions on a nonlinear vehicle model with four degrees of freedom, without causing any degeneration in suspension working limits. Force actuators were mounted parallel to the suspensions. In this new approach, linear combinations of the vertical velocities of the suspension ends and accelerations of the points of connection of the suspension to the body have been used as input variables. The study clearly demonstrates the effectiveness of the fuzzy logic controller for active suspension systems. Suspension working space degeneration is the most important problem in various applications. Decreasing the amplitudes of vehicle body vibrations improves ride comfort. Body bounce and pitch motion of the vehicle are presented both in time domain when travelling over a ramp-step road profile and in frequency domain. The results are compared with those of uncontrolled systems. At the end of this study, the performance and the advantage of the suggested approach and the improvement in ride comfort are discussed.

Active suspension control of a railway vehicle with a flexible body

This study represents a sliding mode control method (SMC) to improve the ride comfort of a railway vehicle with flexible body. The uncomfort and flexibility effects that arise as a consequence of the vehicle body vibrations are minimised using the SMC method. This control method is robust and easily applicable to non-linear systems. Two actuators are located at the front and rear secondary suspension pivot points to reduce the vertical and angular vibrations of the body. This study also compares the controlled and uncontrolled body behaviour by using both their time and frequency responses.

Bilinear Optimal Control of Semi-Active Suspension Taking Account of Coupled Vibration of Elastic Carbody and Truck

Making a vehicle lightweight for high-speed often leads to reduction of flexural-rigidity of the body, and it brings about a problem that elastic vibration deteriorates ride quality with rigid body vibration. In addition to the rigid body vibration, it is also necessary to reduce the fundamental elastic mode of body bending vibration in order to achieve good ride quality. In this study, a FEM model is made by taking into consideration not only the rigid body dynamics, but also the elastic body vibration of a railway vehicle, and the effectiveness of semi-active suspension is examined for the elasticity vehicle. The semi-active suspension designed by the bilinear optimal control theory is used as a means of vibration reduction. The bilinear optimal control theory is applied to the suspension and it is compared with the skyhook control theory which has already been put into practice. As a result, it was shown that the bilinear optimal control theory reduces elantic vibration as well as rigid body vibration, while the skyhook control theory can reduce only rigid body vibration. Particularly, it was made clear that the semi-active suspension located at the truck can control the elastic vibration of vehicle body.

Tilting Control of Railway Vehicle Using Electric Actuators (2nd Report, Feedback Control Using Car Body's Roll Angle)

In order to improve the ride comfort, reducing lateral acceleration is necessary. This paper treats the railway vehicle which runs in curved sections. As a determination method of tilting control quantity operated at present, there are two kind of methods. One is the system using in Japan. It has curve data of the travel interval in the on-board, and it is a method for the tilting order according to the position signal detected from the ground. Another is the system mainly used in Europe, and curve information should not be used, and over centrifugal acceleration which affects the car body is obtained from lateral acceleration in not tilting car truck division, and the tilting quantity has been deduced. The basis of the tilting control method for realizing the inclination goal is also the feedforward tilting control on both systems. In this paper, the feedback type of tilting control, which can maintain the vehicle inclination close to a desired value, is examined ; reduction of vehicle body vibration is also expected with this control. Practically, the curves are obtained by collecting data in real time from the vehicle body traveling through a curve, and this information is utilized in the proposed tilting control method. The effects of the control system are verified by computer simulation study and experiment study.

Perception of Low Frequency Vibrations by Heavy Vehicle Drivers

A study was initiated to identify the levels and frequencies of heavy articulated vehicle body vibrations at which the drivers perceive the ride as uncomfortable. The study involved conducting a subjective assessment survey in which a panel of truck drivers were asked to rate the ride quality provided by a number of road sections with different surface roughness characteristics. The study's objective was achieved by correlating the mean panel ratings (MPRs) to road surface roughness contents in different one-third-octave bands of the roughness spectrum. The results showed that at 100 km/h, truck drivers object mainly to motions resulting from roughness excitations of the low frequency vibration modes of the truck body in the range 1.42 – 5.7 Hz. These results were validated by correlating MPRs with the levels of whole body vibrations measured on the driver's seat in a representative vehicle while traversing some test sections. MPRs were found to correlate well with the measured overall vibration total values and the likely comfort reactions to various magnitudes of overall vibration total values given by ISO 2631–1. The influence on MPRs of vehicle and driver related factors were also investigated and commented upon.

Evaluation of vehicle motion sickness due to vehicle vibration

Recently many studies have been presented for realizing a better riding comfort. Above all, efforts for reducing a vehicle motion sickness of occupants are still needed. Motion sickness is considered to be caused by various factors, for example, personal constitution, driving situation and vehicle vibration. In this paper, the characteristics of vehicle body vibration that influence motion sickness were examined and methods to estimate the motion sickness level due to vehicle vibration were proposed. The proposed methods were applied to verify the effects of the improved suspension system that is installed in recently developed vehicles.