Ride Quality Assessment Research Articles

Exploring the relationship between the International Roughness Index (IRI) and the ISO 8608 roughness coefficient (Gd (n 0))

ABSTRACT Globally, diverse agencies employ varied metrics to gauge road roughness, complicating the exchange of information for pavement maintenance. This study addresses this challenge by establishing a theoretical connection between the International Roughness Index (IRI) and the ISO 8608 Power Spectral Density (PSD)-based roughness coefficient, namely Gd (n 0). Based on random vibration theory, this paper first deduces a closed-form explicit solution for IRI related to Gd (n 0), solidifying a theoretical link. Next, the variability and convergence of the proposed solution are examined through Monte Carlo simulations using a quarter-car vehicle model with the Golden Car parameters. Then, we compare computed results from this study with those existing solutions from past studies, verifying that the proposed solution captures the curve trend well and agrees with the average value of existing solutions based on field measurement data. Finally, this paper proposes the IRI values corresponding to various ISO road class thresholds and a new Gd (n 0) scale for ride quality assessment of highways.

Assessment of Ride Quality and Road Roughness by Measuring the Response from a Vehicle Mounted Android Smartphone

Road surface roughness is considered as one of the most important aspect in functional condition of roads indicating to riding comfort in both transverse and longitudinal direction. For all highway projects maintaining proper surface evenness has been a mandatory requirement from the government of India. In this study, pavement unevenness was estimated using an android-based smartphone and system rely on the movement of a suspension system in response to the unevenness of the road surface travelled by a vehicle. Roughness index (RI) is an indicator to measure the standard road roughness. Conventional way of measuring RI involves usage of bump integrator, profilometer and roughometer. Present study proposes an alternative method to measure roughness using smartphones. The study was carried out in 2 different locations and 3 different smartphones to obtain the magnitude of deflections. Data collected using standard fifth wheel bump integrator is used for validation. Data collected through smartphone i.e., accelerometer sensor details was given as input to Fast Fourier transforms (FFT) to find the magnitude of deflection on the road. The results obtained from smartphones was then correlated with the existing roughness index data collected by standard fifth wheel bump integrator to establish an equation to predict RI using an android mobile.

Evaluation of vibration reduction devices for helicopter ride quality improvement

This work presents the use of a modern helicopter simulation environment for the evaluation of the combined performance of several systems for helicopter ride quality assessment. The proposed framework can handle increasingly detailed aeroservoelastic helicopter models while providing great flexibility and versatility in modeling human biodynamic models for vibration evaluation as well as models of the vibration attenuation devices. A numerical model representative of a medium weight helicopter is used to demonstrate the approach. Lumped parameter models of seat-cushion and human biodynamics are dynamically coupled to the helicopter model to provide a more realistic estimate of the actual vibratory level experienced by the occupants. Two performance indicators are formulated, based on the acceleration of the seat locations and using the ISO-2631 standard: i) qualitative criteria and related vibration dose values of the individuals seated at prescribed locations of a fully occupied helicopter, and ii) an overall rating of the occupants inside the cabin, considering the most and least comfortable seating distributions as the number of occupants changes. To demonstrate the proposed method, three configurations of helicopter-specific passive vibration absorbers are considered.

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.

Ride Quality Assessment of Bus Suspension System through Modal Frequency Response Approach

The ride dynamic characteristics of an urban bus were investigated through simulations with suspension component characteristics and were validated through field measurements. It was performed on highway road at a constant forward speed. A random vibration bus model with two parallel tracks of terrain profile was synthesized with superposition between the left and right sides as well as time delay between front and rear. The bus frequency response model was introduced with embedded modal extraction data to enhance computation efficiency. The simulation results of the bus model were derived in terms of acceleration PSD and frequency-weighted root mean square acceleration along the vertical axes at three locations, namely, driver side, middle, and rear passenger side, to obtain the overall bus ride performance. Another two sets of new leaf spring design were proposed as suspension parameter analysis. The simulation approach provides reasonably good results in evaluating passenger perception on ride and shows that the proposed new spring design can significantly improve the ride quality of the driver and passengers.

Vibration and ride comfort studies on a tracked vehicle

This paper describes a field test conducted on a military tracked vehicle. The accelerations experienced at selected locations on the vehicle for four different types of terrain were recorded and analysed in spectral and statistical modes. The first few natural frequencies of the vehicle were obtained using an in-plane N+2 degree-of-freedom linear dynamic model of the vehicle with two degrees of freedom corresponding to bounce and pitch modes of the hull and N degrees of freedom corresponding to the bounce modes of the N road wheel assemblies. The analytically obtained natural frequencies match with peaks in the experimentally obtained transfer function and acceleration power spectral density curves. From the point of view of crew comfort, acceleration levels encountered in the crew cabin have been compared with those specified in ISO 2631 standard. Ride quality assessment has also been made on the basis of absorbed power.

Ride Quality Assessment with Pavement Profiling Devices

In its pursuit for providing smooth pavements, the Massachusetts Highway Department (MHD) is developing and implementing ride quality specifications as part of its construction quality assurance program. To achieve its goal, MHD, in cooperation with FHWA, sponsored a research project to identify suitable profiling devices with adequate precision and bias for implementing construction quality assurance specifications. The purpose was to evaluate precision and bias of profiling devices based on ASTM E950-94. In 1999, the study was conducted, wherein 16 profiling devices, including high-speed, lightweight, and walking profiling devices, performed 10 repeat runs on eight sites each. Analysis of precision (repeatability) with the international roughness index (IRI) shows that approximately 75% of all tests have an average standard deviation in IRI units below 0.05 mm/m (3 in./mi). The high-speed devices produce better results compared to the lightweight profilers with almost 90% of all tests producing a standard deviation below 0.05 mm/m (3 in./mi) IRI units. Analysis of bias (profiling device, Walking Profiler) with the IRI statistic shows that for all devices, 80% of the left wheelpath tests fall below a bias range of ±0.09 mm/m (6 in./mi) IRI units. Profile analysis and profile lead-in effect were also determined.

Dynamics of off-Road Tracked Vehicles Equipped with Trailing Arm Suspension

A two-dimensional computer simulation model is developed for dynamic analysis of high-mobility tracked vehicles fitted with a trailing arm suspension system. The simulation model is oriented as a design tool for detailed analysis of vehicle suspension dynamics and ride quality assessment. The Lagrangian model formulation of a tracked vehicle is derived by considering a rigid terrain of an arbitrary profile and constant forward vehicle speed. The model incorporates detailed representations of a vehicle suspension system and dynamic wheel-track-terrain interactions. The wheel forces are evaluated based on an adaptive footprint formulation of a wheel/track-terrain contact patch, and the track forces are modelled based on kinematic considerations. The computer model predictions are validated against field measurements, which were gathered from an extensive field testing of an in-service armoured personnel carrier. The comparison between measured and simulated dynamic responses exhibits a fairly close correlation.

Assessment of tracked vehicle suspension system using a validated computer simulation model

A non-linear, in-plane computer simulation model of a typical high-mobility tracked vehicle is developed for suspension dynamic analysis and ride quality assessment. The Langrangian model formulation of the tracked vehicle is derived considering an arbitrary rigid terrain profile and constant vehicle speed. The model incorporates detailed representations of a trailing arm suspension system and dynamic wheel-track-terrain interactions. The computer model predictions are validated against field measurements, which were gathered from tests of an armoured personnel carrier traversing a discrete half-round bump and a random course. A parametric sensitivity analysis was carried out using the validated computer model in order to assess the influence of conventional suspension parameters on the ride performance of the test vehicle. In addition, the ride performance potentials of an alternate hydrogas suspension configuration were investigated.

MBS Modelling, Non-linear Simulation and Linear Analysis Techniques for Integrated Vehicle Control

The study described in this paper is aimed at the development of appropriate vehicle modelling techniques to support research into total motion control systems for future vehicles. The requirement for automatic generation of realistic full vehicle multibody system models capable of non-linear dynamic simulation and linear analysis is explained. The application of the modelling techniques described is then illustrated by a Jeep model. The model and its use for non-linear ride and handling predictions, modal analysis and ride quality assessment is discussed, and conclusions drawn as to the suitability of the modelling approach.

Vehicle Ride Quality and Passenger Comfort

The state of the art in ride quality assessment is reviewed. A portable environmental measuring system (PEMS II) has been developed to simultaneously record variation in motion (in all six degrees of freedom), temperature and pressure for various segments of a ride. The results of extensive studies of passenger reactions to diverse vehicles are presented as a set of models relating human comfort ratings to environmental conditions, vehicles studied include aircraft (commuter planes, S-61 helicopter, Boeing 747, Concorde), trains (conventional and special purpose), buses, and cars. Limited data are available on marine vehicles. Models for aircraft involve vertical and lateral accelerations and noise levels; while models for ground based vehicles also involve roll rate.