Real Road Profiles Research Articles

Two-Layer Parallel Fuzzy Logic Controller Design for Semiactive Suspension System with a Full Car Model

This paper presents research results on semiactive suspension using a fuzzy logic controller. Firstly, a full car model is built with 7 degrees of freedom using a semiactive suspension system at all four wheels. The dynamic equations are converted to the state space representation to facilitate control design and improve accuracy in simulation design. Then, a two-layer parallel fuzzy logic controller is designed with 49 and 25 rules for two fuzzy inference systems. In this way, the fuzzy logic controller is able to respond to a wide operating range of the system and the output force is smoother. Finally, the evaluation results are performed in the frequency and time domains with a real random road profile, and they showed that the root mean square value of the signals when using a semiactive suspension system with the proposed fuzzy logic controller decreased by over 25% compared to the passive suspension system. This clearly demonstrates the effectiveness of the proposed controller in improving the ride comfort, the road holding and ensuring the suspension travel of cars.

Road Profile Modelling Based on Measurement for Fire Truck Simulation

The unevenness of the road reduces the life of the vehicle’s suspensions, and the resulting harmful vibrations can also lead to the failure of other structures. In case of special superstructures like fire trucks, valuable firefighting equipment can also be damaged. Since there is little available literature dealing with the vibrations generated during the use of firefighting vehicles, in this research work a real road profile based on data from geodetic measurements was generated for numerical simulation. The suspension of the vehicle taking into account the parameters of a heavy-duty firefighting vehicle was also modelled, and then the effects of road failures using computer simulation were investigated. The road profile was implemented in the simulations with spline polynomials and the fire truck was simulated as a full vehicle model. The aim of the research is to compare the achieved simulation results with data from other vehicle research studies, thereby achieving more accurate results that can also be applied in practice, contributing to vehicle design and safe operation.

Road profile generation based on real road profile for the Whole life pavement performance input data

Road profile is one of the inputs for the whole life pavement performance (WLPP) model. It used to predict vehicle loading. In this study, few road profiles were generated based on sparse road roughness measurements by road scanner. The Profile Viewing, ProVAL Analysis software and Matlab were used to filter unwanted wavelength, visualize the measured road profile data, and obtain profile International Roughness Index (IRI) and generate road profile base on Power Spectral Density (PSD) approximation equation. Calibrations between generated and measured road profiles were done by computing the correlation coefficient values. As a result, few road profiles of 100 m length have been generated based on the federal and state road profiles. The generated road profiles and measured road profiles are closely in shape.

The functioning investigation of the network semi-active damping system for wheeled vehicle

The tasks related to the construction of a united semi-active system for damping vibrations of the supporting platform (chassis) of a wheeled vehicle (WV), taking into account the real road profile were considered. The influence estimation of the network on the functioning resulting quality of the entire united damping system is carried out. The modeling of the network united of the model of one wheelset, the possible law of control of the suspension, the central processor and the physical model of the CAN network by using the National Instruments equipment is performed. The results of the experiments, both purely mathematical and with a physical network model, showed the performance of the proposed solutions. Keywords CAN-tire; semi-active suspension system; identification; modeling

Effects of Vehicular Speed on the Assessment of Pavement Road Roughness

Good ride quality is a fundamental requirement for all road networks in modern countries. For this purpose, it is essential to monitor and evaluate the effect of irregularities on road pavement surfaces. In the last few decades, many roughness indices have been proposed, with the aim to represent shortly the pavement surface characteristics and the relative performances, using a single number and a correspondent scale of values. In this work, a comparison between three different evaluation methods (International Roughness Index, ISO 8608 road profile classification and frequency-weighted vertical acceleration awz according to ISO 2631) was carried out, applying these methods to some real road profiles. The similarities and differences between the obtained results are described, evaluating the effect of the road characteristic speed on the roughness thresholds. In fact, the specific aim of the analyses is to underline the need to use different thresholds depending on the speed at which the vehicular traffic can travel on the road sections. In this way, it will be possible to identify appropriate thresholds for the various types of roads, having for each of them a specific range of design or operating speed.

Frequency Domain Analysis of Tractor Tyre Enveloping Properties

Main source of vibration excitation for off-road vehicles are ground profile undulations. Most unprepared terrains are characterized by wavelength of unevenness that is of the order of magnitude of the contact length between tire and ground, so that, due to its shape and elasticity, tire actually behaves as geometric low-pass filter transforming real road profile geometry into effective vehicle vibration excitation. Since this effective profile represents real vehicle excitation, it is of interest to study this filtering behaviour in more depth. In this work, investigation of this kind of tire response has been studied for agricultural tractor tire rolling quasistatically over singular road obstacle. Frequency analysis of road excitation and tyre response was carried out in order to obtain their spectra and frequency response function magnitude of the tyre as filter was obtained by dividing input by output spectra. Final assessment of frequency response function magnitude was obtained by averaging instances obtained for different dimensions of input obstacles.

Vibration isolation analysis of new design OEM damper for malaysia vehicle suspension system featuring MR fluid

The applications of semi-active damper employing magnetorheological (MR) fluids keep increasing in fulfilling the demand to control undesired vibration effect. The aim of this study is to introduce the new design of damper for Malaysian vehicle model as well to evaluate its effectiveness in promoting comfort. The vibration isolation performance of the OEM damper featuring MR fluid was analysed physically under real road profile excitation experimentally. An experiment using quarter car rig suspension and LMS SCADAS Mobile was conducted to demonstrate the influence of current in controlling the characteristics of MR fluid in alter the damping behaviour under 5 cm bump impact. Subsequently, the displacement values were measured with respect to time. The new design OEM damper featuring MR fluid was validated by comparing the data with original equipment manufacturer (OEM) passive damper results under the same approach of testing. Comparison of numerical data of the new design OEM damper shown that it can reduce the excitation amplitude up to 40% compared to those obtained by OEM passive damper. Finally, the new design OEM damper featuring MR fluid has effectively isolated the disturbance from the road profile and control the output force.

Ride Quality Due to Road Surface Irregularities: Comparison of Different Methods Applied on a Set of Real Road Profiles

Road roughness evaluation can be carried out using different approaches. Among these, the assessment of ride quality level perceived by road users is one of the most-used. In this sense, different evaluation methods have been developed in order to link the level of irregularities present on road surface profiles with the induced detrimental effects in terms of discomfort. In particular, relationships between wavelength content of road profiles and consequent level of comfort perceived had been investigated by using, in general, a mean panel ratings approach. In this paper, four ride quality evaluation methods (Ride Number, Michigan Ride Quality Index (RQI), Minnesota Ride Quality Index and frequency-weighted vertical acceleration, awz, according to ISO 2631 were applied to a set of real road profiles. The obtained results were analyzed, investigating a possible relation between the different indices, comparing them also with the most-used road roughness method worldwide: the International Roughness Index (IRI). The analyses carried out in this work have highlighted how the various rating scales may lead to a different ride quality assessment of the same road pavements. Furthermore, comparing the awz with the values obtained for the other three methods, it was found that their rating scales are set for speeds within the range 80–100 km/h. For this reason, it is necessary to identify new thresholds to be applied for lower speeds, as in the case of urban roads. In this sense, the use of the ISO 2631 approach would seem to be a useful tool.

Use of generated artificial road profiles in road roughness evaluation

In the evaluation of road roughness and its effects on vehicles response in terms of ride quality, loads induced on pavement, drivers’ comfort, etc., it is very common to generate road profiles based on the equation provided by ISO 8608 standard, according to which it is possible to group road surface profiles into eight different classes. However, real profiles are significantly different from the artificial ones because of the non-stationary feature of the first ones and the not full capability of the ISO 8608 equation to correctly describe the frequency content of real road profiles. In this paper, the international roughness index, the frequency-weighted vertical acceleration awz according to ISO 2631, and the dynamic load index are applied both on artificial and real profiles, highlighting the different results obtained. The analysis carried out in this work has highlighted some limitation of the ISO 8608 approach in the description of performance and conditions of real pavement profiles. Furthermore, the different sensitivity of the various indices to the fitted power spectral density parameters is shown, which should be taken into account when performing analysis using artificial profiles.

Energy-harvesting potential of automobile suspension

ABSTRACTThis study is aimed quantify dissipated power in a damper of automobile suspension to predict energy harvesting potential of a passenger car more accurately. Field measurements of power dissipation in a regenerative damper are still rare. The novelty is in using the broad database of real road profiles, a 9 degrees-of-freedom full-car model with real parameters, and a tyre-enveloping contact model. Results were presented as a function of road surface type, velocity and road roughness characterised by International Roughness Index. Results were calculated for 1600 test sections of a total length about 253.5 km. Root mean square of a dissipated power was calculated from 19 to 46 W for all four suspension dampers and velocity 60 km/h and from 24 to 58 W for velocity 90 km/h. Results were compared for a full-car model with a tyre-enveloping road contact, full-car and quarter-car models with a tyre–road point contact. Mean difference among three models in calculated power was a few per cent.

Nonlinear state estimation for suspension control applications: a Takagi-Sugeno Kalman filtering approach

A new nonlinear state estimation approach, which combines classical Kalman filter theory and Takagi-Sugeno (TS) modeling, is proposed in this paper. To ensure convergence of the TS observer, conditions are derived that explicitly account for the TS model's confined region of validity. Thereby, the secured domain of attraction (DA) of the TS error dynamics is maximized within given bounds. The TS Kalman filtering concept is then applied to a hybrid vehicle suspension configuration, whose nonlinear dynamics are exactly represented by a continuous-time TS system. The benefit of the novel estimation technique is analyzed in comparison with the well-known EKF and UKF variants in simulations and experiments of a passive and an actively controlled suspension configuration in a quarter-car set-up. Employing a real road profile as disturbance input, the TS Kalman filter shows the highest estimation quality of the concepts studied. Moreover, as its computational complexity adds up to only one third of the one involved with the classical methods, the new approach operates remarkably efficient.

Nonlinear vibration of semitrailer suspension: wavelet and multiscale entropy-based approaches

We examine the dynamical response of a semitrailer suspension to a real road profile under two different loads. The trailer is a low loader for transporting heavy and large loads, the configuration of which can be adjusted as desired. Experiments are performed on both unladen and 57-ton laden trailers. The acceleration of unsprung and sprung parts of the vehicle is measured. The obtained acceleration time series are then analyzed using the Fourier and wavelet transforms as well as the multiscale entropy approach. The data analysis results reveal transmission of suspension vibration and complexity of vehicle vertical acceleration as a response to the road profile.

ETS fuzzy driver model for simultaneous longitudinal and lateral vehicle control

In this paper, evolving Takagi-Sugeno (eTS) fuzzy driver model is proposed for simultaneous lateral and longitudinal control of a vehicle in a test track closed to traffic. The developed eTS fuzzy driver model can capture human operator’s driving expertise for generating desired steering angle, throttle angle and brake pedal command values by processing only information which can be supplied by the vehicle’s on-board control systems in real time. Apart from other fuzzy rule based (FRB) models requiring human expert knowledge or off-line clustering, the developed eTS driver model can adapt itself automatically, even ‘from scratch’, by an on-line learning process using eTS algorithm while human driver is supervising the vehicle. Proposed eTS fuzzy driver model’s on-line human driver identification capability and autonomous vehicle driving performance were evaluated on real road profiles created by digitizing two different intercity express ways of Turkey in IPG© CarMaker® software. The training and validation simulation results demonstrated that eTS fuzzy driver model can be used in product development phase to speed up different tests via realistic simulations. Furthermore eTS fuzzy driver model has an application potential in the field of autonomous driving.

Road profile estimation using wavelet neural network and 7-DOF vehicle dynamic systems

Road roughness is a broad term that incorporates everything from potholes and cracks to the random deviations that exist in a profile. To build a roughness index, road irregularities need to be measured first. Existing methods of gauging the roughness are based either on visual inspections or using one of a limited number of instrumented vehicles that can take physical measurements of the road irregularities. This paper more specifically focuses on the estimation of a road profile (i.e., along the “wheel track”). This paper proposes a solution to the road profile estimation using a wavelet neural network (WNN) approach. The method incorporates a WNN which is trained using the data obtained from a 7-DOF vehicle dynamic model in the MATLAB Simulink software to approximate road profiles via the accelerations picked up from the vehicle. In this paper, a novel WNN, multi-input and multi-output feed forward wavelet neural network is constructed. In the hidden layer, wavelet basis functions are used as activate function instead of the sigmoid function of feed forward network. The training formulas based on BP algorithm are mathematically derived and a training algorithm is presented. The study investigates the estimation capability of wavelet neural networks through comparison between some estimated and real road profiles in the form of actual road roughness.

Vibrations of a vehicle excited by real road profiles

Based on experimental data obtained from the Lublin III delivery car, we have performed a vibration analysis of the vehicle suspension system. Vertical accelerations on the left and right sides of the suspension system were measured. Experiments were carried out on three types of road surfaces: (a) asphalt, (b) sett, and (c) railway cross. The acceleration signals were examined using Fourier transform, multiscale entropy analysis and continuous wavelet transform. These methods reveal the characteristics of the vibration patterns produced by the various road surface profiles. Our results can be used to assess the efficacy of a vehicle suspension system under different road conditions.

Road profile estimation using neural network algorithm

This paper more specifically focuses on the estimation of a road profile (i.e., along the “wheel track”). Road profile measurements have been performed to evaluate the ride quality of a newly constructed pavement, to monitor the condition of road networks in road management systems, as an input to vehicle dynamic systems, etc. The measurement may be conducted by a slow-moving apparatus directly measuring the elevation of the road or using a means that measures surface roughness at highway speeds by means of accelerometers coupled with high speed distance sensors, such as laser sensors or using a vehicle equipped with a response-type road roughness measuring system that indirectly indicate the user’s feelings of the ride quality. This paper proposes a solution to the road profile estimation using an artificial neural network (ANN) approach. The method incorporates an ANN which is trained using the data obtained from a validated vehicle model in the ADAMS software to approximate road profiles via the accelerations picked up from the vehicle. The study investigates the estimation capability of neural networks through comparison between some estimated and real road profiles in the form of actual road roughness and power spectral density.

Non-uniqueness of Single-number Indicators of Longitudinal Road Profiles

ABSTRACT Currently used single-number indicators (SNIs) of longitudinal road unevenness do not provide information on the frequency content of the road profile. The frequency content can be defined in terms of a power spectral density (PSD) measure, waviness, and is important from the viewpoint of vehicle vibration response. In this paper, the problems associated with the non-uniqueness of single-number indicators are discussed, quantitative measures of waviness are proposed and corresponding values are estimated for some common SNIs. The methods for providing waviness information to complement particular SNIs are presented and verified with three real road profile records. Being respectful of the weakness of single-number indicators, only the standard unevenness index, C and a modified International Roughness Index (IRI120) for v = 120 km/h can conditionally be admitted. Generally speaking, to compensate for the non-uniqueness of single-number indicators, the addition of a waviness value is recommended for all indicators considered and suitable calculation methods are proposed.

Non-uniqueness of Single-number Indicators of Longitudinal Road Profiles

ABSTRACT Currently used single-number indicators (SNIs) of longitudinal road unevenness do not provide information on the frequency content of the road profile. The frequency content can be defined in terms of a power spectral density (PSD) measure, waviness, and is important from the viewpoint of vehicle vibration response. In this paper, the problems associated with the non-uniqueness of single-number indicators are discussed, quantitative measures of waviness are proposed and corresponding values are estimated for some common SNIs. The methods for providing waviness information to complement particular SNIs are presented and verified with three real road profile records. Being respectful of the weakness of single-number indicators, only the standard unevenness index, C and a modified International Roughness Index (IRI120) for v = 120 km/h can conditionally be admitted. Generally speaking, to compensate for the non-uniqueness of single-number indicators, the addition of a waviness value is recommended for all indicators considered and suitable calculation methods are proposed.

Vertical Vibrations of a Vehicle Excited by Real Road Profiles.

AbstractWe analyze experimental acceleration data obtained from the delivery car vibration test in working conditions. The vertical components of unsprung and sprung mass accelerations have been analyzed by using the Fourier analysis. In particular we examine the response of the sprung mass on various road excitations and conclude the efficiency of the car suspension. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Optimal Control of an 8‐DOF Vehicle Active Suspension System Using Kalman Observer

In this paper, an 8‐DOF model including driver seat dynamics, subjected to random road disturbances is used in order to investigate the advantage of active over conventional passive suspension system. Force actuators are mounted parallel to the body suspensions and the driver seat suspension. An optimal control approach is taken in the active suspension used in the vehicle. The performance index for the optimal control design is a quantification of both ride comfort and road handling. To simulate the real road profile condition, stochastic inputs are applied. Due to practical limitations, not all the states of the system required for the state‐feedback controller are measurable, and hence must be estimated with an observer. In this paper, to have the best estimation, an optimal Kalman observer is used. The simulation results indicate that an optimal observer‐based controller causes both excellent ride comfort and road handling characteristics.