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Showing papers in "International Journal of Heavy Vehicle Systems in 2014"


Journal ArticleDOI
TL;DR: The history of B-WIM is looked at, beginning with early work on weigh-in-motion technologies in the 1960s leading to its invention by Fred Moses and George Goble in the USA in the mid 1970s.
Abstract: Bridge weigh-in-motion (B-WIM) is a method by which the axle weights of a vehicle travelling at full highway speed can be determined using a bridge instrumented with sensors. This paper looks at the history of B-WIM, beginning with early work on weigh-in-motion (WIM) technologies in the 1960s leading to its invention by Fred Moses and George Goble in the USA in the mid 1970s. Research initiatives in Australia and Europe have focused on improving B-WIM accuracy. The moving force identification (MFI) method models the dynamic fluctuation of axle forces on the bridge and holds particular promise. B-WIM accuracy depends on bridge site conditions as well as the particular data processing algorithm. The accuracy classifications of several B-WIM installations reported in the literature are summarised in this paper. Current accuracy levels are sufficient for selecting vehicles to be weighed using static scales, but insufficient for direct enforcement. Copyright © 2014 Inderscience Enterprises Ltd.

73 citations


Journal Article
TL;DR: In this article, a semi-trailer incorporating a chassis rolls dynamometer and a second trailer containing the necessary emissions and controls equipment is used for testing methanol, diesel, jet fuel and natural gas powered buses.
Abstract: A significant number of city buses, city tractors and utility trucks are already operating on alternative fuels such as methanol, ethanol and natural gas. In response to the need for reliable emissions data from these vehicles, a transportable laboratory has been constructed and has operated on six different dates over the past nine months. This laboratory consists of a semi–trailer incorporating a chassis rolls dynamometer and a second trailer containing the necessary emissions and controls equipment. The semi–trailer can be lowered to the ground using specially designed hydraulic jacks and the vehicle to be tested is driven up ramps onto the rolls. Power is taken from the vehicle to flywheels and air–cooled eddy–current absorbers which simulate inertia and road load. The vehicle is driven through a speed–time cycle by a driver receiving a prompt on a screen, and vehicle speed is monitored by shaft encoders at three locations. The load applied to the vehicle is found using a road load equation: part of this energy is dissipated in rotating component parasitic losses determined during a calibration procedure and the remainder is dissipated by the computer–controlled power absorbers. Tailpipe emissions are ducted to a dilution tunnel, powered by a blower with critical flow venturies, while probes in the tunnel draw continuous samples to an analyser bench. Total hydrocarbons, oxides of nitrogen, carbon monoxide and carbon dioxide are all monitored, while a composite particulate matter sample is obtained on a filter. A bank of such data for methanol, diesel, jet fuel and natural gas powered buses operating primarily on the Central Business District Cycle is presently being gathered and analysed.

60 citations


Journal Article
TL;DR: In this article, the authors describe a prototype Vehicle-Road Surface Pressure Transducer Array (VRSPTA) system developed for the measurement of the tyre/pavement interface stresses of a moving wheel load.
Abstract: In order to design more economical pavements, it is necessary to use the most accurate input parameters possible. Tyre/pavement interface stresses are one of the important inputs in any pavement design system and therefore requires appropriate definition. This paper describes a prototype Vehicle–Road Surface Pressure Transducer Array (VRSPTA) system developed for the measurement of the tyre/pavement interface stresses of a moving wheel load. It illustrates that the tyre/pavement stresses caused by a moving wheel can be adequately measured in vertical, transverse and longitudinal directions. As this was an experimental system which contains some inaccuracies, certain improvements to the current system are suggested.

37 citations


Journal Article
TL;DR: In this paper, a simple methodology is proposed to estimate the rollover threshold of partially filled liquid cargo vehicles by balancing the total overturning and restoring moments using a single roll degree-of-freedom (DOF) model of the rigidly suspended tank vehicle.
Abstract: A simple methodology is proposed to estimate the rollover threshold of partially filled liquid cargo vehicles. The primary overturning moment caused by the lateral motion of the liquid cargo within the circular, elliptic or modified–oval cross–section tanks is derived as a function of the lateral acceleration, roll angle, fill level, and the tank geometry. The rollover threshold is estimated using two different methods. In the first method, the rollover threshold is estimated by balancing the total overturning and restoring moments using a single roll degree–of–freedom (DOF) model of the rigidly suspended tank vehicle. The compliant properties of the tyres and suspension are incorporated in the analysis through a compliance factor. The roll moments arising from the multiple–axle suspension and tyres, individual axle loads, and lateral displacement are computed and integrated in the analysis in the second method. The rollover threshold of a tractor–tank–semitrailer is estimated using both methods for different fill levels. The estimated values of rollover threshold are compared to those obtained from a comprehensive kineto–static roll plane model of the tank vehicle. The results show that the proposed simplified methods can provide an accurate estimation of rollover threshold for constant as well as varying payloads.

29 citations


Journal ArticleDOI
TL;DR: To further assess vibration exposure on haul trucks and front-end wheel loaders, follow-up investigations were conducted at two US crushed stone operations to evaluate factors such as load/no-load conditions, speed, load capacity, vehicle age, and seat transmissibility relative to vibration exposure.
Abstract: To further assess vibration exposure on haul trucks (HTs) and front-end wheel loaders (FELs), follow-up investigations were conducted at two US crushed stone operations. The purpose was to: 1) evaluate factors such as load/no-load conditions, speed, load capacity, vehicle age, and seat transmissibility relative to vibration exposure; 2) compare exposure levels with existing ISO/ANSI and EUGPG guidelines. Increasing HT speed increased recorded vibration at the chassis and seat as expected. Neither vehicle load nor vehicle speed increased transmissibility. Increasing HT size and age did show transmissibility decreasing. HT dominant-axis wRMS levels (most often the y-axis, lateral or side-to-side direction) were predominantly within the health guidance caution zone (HGCZ). However, several instances showed vibration dose value (VDV) above the exposure limit value (ELV) for the ISO/ANSI guidelines. VDV levels (all dominant x-axis or fore-aft) were within and above the HGCZ for the EUGPG and above the HGCZ for ISO/ANSI guidelines.

29 citations


Journal Article
TL;DR: In this paper, a concept of effective lateral acceleration is proposed to characterize the relative roll instability under dynamic directional manoeuvres of heavy vehicles to determine their dynamic rollover characteristics, and the results of the study are established that the dynamic roll-over threshold based on effective lateral accelerations in most cases is either slightly lower or equal to the static rollover threshold acceleration.
Abstract: Different measures of relative roll instability of heavy vehicles are investigated to determine their dynamic rollover characteristics. Analytical models of different vehicle combinations are presented and a concept of effective lateral acceleration is proposed to characterize the relative roll instability under dynamic directional manoeuvres. The analytical models for a five–axle tractor semi–trailer combination and an eight–axle A–train double are analysed to establish the dynamic rollover threshold based upon relative roll instability criterion and effective lateral acceleration. The dynamic rollover threshold of the vehicle, derived for different suspension properties and operating conditions, is compared with the corresponding static rollover threshold of the vehicle. From the results of the study, it is established that dynamic rollover threshold based on effective lateral acceleration in most cases is either slightly lower or equal to the static rollover threshold acceleration. The difference between the dynamic and static rollover thresholds is less than 5% for the vehicle configurations and the steering manoeuvres considered in the study. The static rollover threshold may thus be conveniently employed to estimate the dynamic rollover propensity of heavy vehicles.

23 citations


Journal Article
TL;DR: In this article, the dynamic interaction between bridges and vehicles increases when the natural frequencies of the dynamic wheel forces associated with body bounce (2 to 4 Hz) match those of the bridge.
Abstract: The dynamic interaction between bridges and vehicles increases when the natural frequencies of the dynamic wheel forces associated with body bounce (2 to 4 Hz) match those of the bridge This interaction with body bounce vibrations does not occur in short span bridges as their natural frequencies are greater than 8 Hz However, research conducted as part of the Organisation for Economic Co–operation and Development DIVINE international research project has demonstrated that dynamic coupling occurs in short span bridges with natural frequencies corresponding to those of axle hop (10 to 15 Hz) The dynamic response of a 914 m (30 ft) span prestressed concrete bridge and the dynamic wheel forces were measured simultaneously for both a conventional steel leaf spring and air suspensions fitted to a tri–axle trailer The dynamic response of the bridge was large but sensitive to speed, road roughness and suspension Generally the peak bridge deflections were smaller when the air suspensions were fitted except when axle hop was induced by roughness In this case, at critical speeds, the vehicle fitted with the air suspension and the bridge coupled to give large deflections and multiple fatigue cycles during the passage of the test vehicle

21 citations


Journal Article
TL;DR: In this article, a computer controlled driver's seat suspension model for heavy trucks is presented, which isolates the driver from external excitation and minimises the transmission of vibration to the driver upper body.
Abstract: This paper presents a computer controlled driver's seat suspension model for heavy trucks that isolates the driver from external excitation and minimises the transmission of vibration to the driver upper body. The vehicle is modelled as a 2 degrees–of–freedom lumped mass system with suspension characteristics of a single axle vehicle and a tyre with a mass and a stiffness which conform to a truck model known as a "quarter–vehicle" model. The seat is supported by a linear spring and damper whose characteristics are time dependent. The ride comfort is measured by an index of accelerations of the human body parts. An optimisation of the seat suspension parameters is carried out by minimising the work performed by the internal forces to the driver, as well as the body accelerations. In this paper, both constrained and unconstrained optimisation of the seat suspension design parameters are performed seeking for optimal values of the damping and spring constants as a function of time. Based on the results of the constrained optimisation, two approximate solutions are proposed: the semi–active damping concept and the variable structure controller.

20 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present a systematic design process for an ergonomic workstation, in which the design scope is clarified by utilising the selection of an appropriate datum point and design criteria, the definition of standard bus driving postures, and the construction of hierarchies of the design and anthropometric variables.
Abstract: A bus operator workstation design neglecting ergonomic features can cause undesirable effects, such as overall discomfort and increased injuries. This paper presents a systematic design process for an ergonomic workstation. In the design process, the design scope is clarified by utilising the selection of an appropriate datum point and design criteria, the definition of standard bus driving postures, and the construction of hierarchies of the design and anthropometric variables. The relational attributes between the design and anthropometric variables are evaluated by a relationship analysis, and then utilised for the formulation of functional design relationships in conjunction with the geometrical configuration. These functional design relationships effectively present the interdependency of the workstation elements and enhance the flexibility of the acquired design knowledge. The design guidelines are recommended based on the functional design relationships and compared to results of other similar studies. Finally, the design guidelines are verified by a laboratory–based mockup which is evaluated by 103 jurors.

16 citations


Journal Article
TL;DR: In this article, the authors presented an overview of pitch-plane models for trucks and combination vehicles with emphasis on modelling suspension systems and the tyre-road interface, as well as parameters for characterising the truck population.
Abstract: The urgent need to improve the understanding of truck damage to highway pavements has intensified interest in modelling the mechanics of the process. The process is being investigated by simulating trucks and combination vehicles to predict dynamic loads along the roadway in response to road roughness inputs. The dynamic loads are transformed into stresses imposed on the surface of pavement structural models from which the pavement responses and damage can be evaluated. This paper gives an overview of pitch–plane models for trucks and combination vehicles with emphasis on modelling suspension systems and the tyre–road interface. Parameters for characterising the truck population are discussed and presented.

16 citations


Journal ArticleDOI
TL;DR: In this article, the dynamic interaction of liquid cargo with the tractor semi-trailer vehicle is evaluated by integrating a dynamic slosh model of the partly filled tank with five-degrees-of-freedom.
Abstract: In this paper the directional response and roll stability characteristics of a partly filled tractor semi-trailer vehicle, with different tank shapes, under different parameters and conditions are investigated. The effective parameters and conditions in the stability of a tractor semi-trailer carrying liquid can be considered as tank shape, fill volume and vehicle steering input. The dynamic interaction of liquid cargo with the tractor semi-trailer vehicle is evaluated by integrating a dynamic slosh model of the partly filled tank with five-degrees-of-freedom of a tractor semi-trailer tank. The vehicle model is analysed for the different tank cross-sections, circular, modified-oval and reuleaux triangle. The dynamic fluid slosh within the tank is modelled using three-dimensional Navier-Stokes equations, coupled with the volume-of-fluid equations and analysed by using the FLUENT software. The coupled tank-vehicle model is subsequently analysed to determine the roll stability characteristics for different cross-sections of tank, fill volumes and manoeuvres.

Journal Article
TL;DR: In this article, the influence of linear symmetric and asymmetric suspension damping on the dynamic wheel loads transmitted to the pavement is analyzed through response analysis of a quarter-truck model.
Abstract: The influence of linear symmetric and asymmetric suspension damping on the dynamic wheel loads transmitted to the pavement is analytically investigated through response analysis of a quarter–truck model. The vehicle models comprising linear and asymmetric suspension damping in conjunction with a linear, leaf and air spring are analysed to derive the dynamic wheel loads, and vertical vibration of the sprung and unsprung masses. While the force–displacement characteristics of the leaf–spring are characterized by a semi–empirical relation derived from the measured data, the force–displacement properties of the air spring are derived using the gas laws. The analytical model is analysed for excitations arising from a smooth as well as rough roadway to derive the influence of suspension damping on the dynamic load coefficient (DLC) and the sprung mass acceleration response. The results demonstrate a clear analogy between the DLC and the vehicle ride quality. The linear and air suspensions with damping ratio near 0.10 range can considerably reduce the DLC. The corresponding vertical acceleration response of the sprung mass in the ride frequencies (4–8 Hz), however, increases slightly with an increase in suspension damping. Although the inter–layer friction inherent within a leaf spring suspension yields considerable dissipative properties, additional light viscous damping can further reduce the DLC considerably. The suspension damping, asymmetric in compression and rebound, tends to reduce the DLC with only minimal effect on the vehicle ride vibration in the ride frequency range. The reduction in DLC, somewhat less than that realized with symmetric and linear damping, varies with the degree of asymmetry.

Journal Article
TL;DR: In this paper, the authors present a method for developing a chassis test for a specific and typical class of vehicles which will mirror the Federal Test Procedure (FT) as closely as possible for purposes of emissions measurement.
Abstract: The objective of this paper is to present a method for developing a chassis test for a specific and typical class of vehicles which will mirror the Federal Test Procedure (FT) as closely as possible for purposes of emissions measurement. Emphasis will be placed on development of a preliminary heavy duty chassis cycle for specific over–the–road class 8 trucks which will reflect the FTP currently imposed on heavy duty diesel engines.

Journal Article
TL;DR: In this paper, the authors describe a series of tests conducted on a UK trunk road, in which the dynamic tyre forces generated by over 1500 heavy goods vehicles (HGVs) were measured using a load measuring mat containing 144 capacitive strip sensors.
Abstract: This paper describes a series of tests conducted on a UK trunk road, in which the dynamic tyre forces generated by over 1500 heavy goods vehicles (HGVs) were measured using a load measuring mat containing 144 capacitive strip sensors. The data was used to investigate the relative road damaging potential of the various classes of vehicles, and the degree of spatial repeatability of tyre forces present in a typical highway fleet. Approximately half the vehicles tested were found to contribute to a spatially repeatable pattern of pavement loading. On average, air suspended vehicles were found to generate lower dynamic load coefficients than steel suspended vehicles. However, air suspended vehicles also generated higher mean levels of theoretical road damage (aggregate force) than steel suspended vehicles, indicating that the ranking of suspensions depends on the pavement damage criterion used.

Journal ArticleDOI
TL;DR: In this article, the performance of suspension systems for off-road vehicles is evaluated using a half-car model with three types of suspensions: passive, hybrid semi-active and linear quadratic regulator (LQR) active suspension systems.
Abstract: The work aims to study the performance of suspension systems for off-road vehicles. Three type of suspensions - passive, hybrid semi-active and Linear Quadratic Regulator (LQR) active suspension systems - are presented using half-car model. These systems are compared in terms of ride quality, handling, road holding and ability to support vehicle static weight through transient and statistical analyses. Results indicate the responses of the proposed LQR active system to random road excitation relative to the passive system are better than the hybrid semi-active system in terms of the criteria mentioned above.

Journal ArticleDOI
TL;DR: In this article, the steering control of an articulated surface mining large wheel loader navigating a predefined path is modeled by modeling each system of the articulated vehicle separately and merging them to form an overall system.
Abstract: This research is conducted on machine dynamics and steering control of an articulated surface mining large wheel loader (LWL) navigating a predefined path. Modelling a LWL based on computational multibody dynamics is achieved by modelling each system of the articulated vehicle separately then merging them to form an overall system of an articulated vehicle navigating a predefined path. This model includes the front and rear frames, articulated hinge, steering actuators, tyre model, steering controller and a predefined path. Fuzzy and PID steering controllers are developed and simulated. Results show that it is possible to model large articulated vehicles as a multibody mechanical system. Both of the developed controllers are able to control the lateral and longitudinal motion of the vehicle and drive the machine over the desired path accurately. The fuzzy logic controller has longer rising time but shorter settling time when compared with the PID controller.

Journal Article
TL;DR: Two human body models were substantially more effective in predicting the effects of cushions on human resonance behaviour than the model that represented the human body as an equivalent rigid mass.
Abstract: Analytical models of the human body are a potential tool for optimizing vehicle seat cushion and seat suspension design parameters to aid in minimizing the effects of whole–body vibration. The objective of this study was to apply three human body models to evaluate and compare the predicted effects of seat cushions and a low frequency (1–2 Hz) seat–suspension on human whole–body mechanical impedance and transmissibility. The three degree–of–freedom (3–DOF) and five degree–of–freedom (5–DOF) human body models predicted similar cushion effects at low frequencies: increased vibration transmission to the torso or chest. The 5–DOF model was also effective in predicting cushion effects at higher frequencies: decreased transmission of vibration to the spinal column. Both the 3–DOF and 5–DOF models were substantially more effective in predicting the effects of cushions on human resonance behaviour than the model that represented the human body as an equivalent rigid mass. It was found that all three human body models predicted similar human biodynamic effects for the combined cushion and low frequency seat–suspension.

Journal Article
TL;DR: In this paper, the authors describe an experimental program aimed at developing a cost-effective rating procedure for suspensions using a general-purpose two post servohydraulic shaker facility.
Abstract: It is well established that different heavy vehicle suspension systems generate different levels of dynamic loading on pavements, and it is generally accepted that higher dynamic loads cause more pavement wear. Thus some suspensions can be categorised as being more 'road–friendly' than others. Pavement maintenance is a substantial budget item for all road authorities and clearly there are benefits in encouraging the use of 'road–friendly' suspensions. However, in order to do this, it is necessary to establish a method for rating suspensions. This paper describes an experimental programme aimed at developing a cost–effective rating procedure for suspensions using a general–purpose two post servohydraulic shaker facility. The vehicle's on–road behaviour is monitored using relatively simple instrumentation, and this measured response is then reproduced in the laboratory using the shakers to excite the vehicle. Wheel forces are measured with instrumentation on the actuators. This procedure has been demonstrated successfully on a test vehicle and the results are presented. Possible extensions and improvements to the method are postulated.

Journal ArticleDOI
TL;DR: In this article, a mathematical model of a medium weight truck has been formulated which takes into account the physical and dynamic characteristics of the fluid cargo, including partial filling ratio and liquid cargo viscosity, to investigate the ride behavior of trucks carrying two spherical fluid containers.
Abstract: Liquid motion in partially filled containers generates slosh forces and moments which affect the ride behaviour and stability of fluid cargo trucks. The main objective of the paper is to investigate the ride behaviour of trucks carrying two spherical fluid containers. A mathematical model of a medium weight truck has been formulated which takes into account the physical and dynamic characteristics of the fluid cargo. In this model, the fluid cargoes in both tanks are simulated as nonlinear pendulums with specific damping coefficients. The Runge–Kutta method has been used to solve the nonlinear equations of motion of the vehicle system in the time domain. The vehicle is excited by two sources at the same time. The first is a vertical harmonic excitation expressing road irregularities. The second is a relatively small longitudinal deceleration in the direction of motion. The partial filling ratio and liquid cargo viscosity are shown to play major roles in the vehicle ride behaviour. Finally, result analysis and discussions are made.

Journal Article
TL;DR: In this paper, the authors present a set of algorithms for piloting an autonomous planetary rover along a planned path, performing real-time obstacle avoidance and improving a dead reckoning capability, using linear regulation (feedback) of position and orientation errors, measured with respect to the planned path trajectory.
Abstract: This paper presents a set of algorithms for piloting an autonomous planetary rover along a planned path, performing real–time obstacle avoidance and improving a dead reckoning capability. Path tracking is accomplished using linear regulation (feedback) of position and orientation errors, measured with respect to the planned path trajectory. Obstacle avoidance is performed through the application of the concept of an artificial potential field to data that can be acquired using a scanning rangefinder. Dead reckoning is improved by the algorithmic filtering and fusing of odometry and inertial navigation data streams. Computer simulation is used to illustrate the path–tracking and obstacle–avoidance capabilities, and experimental data is used to show how sensor fusion mitigates the effects of wheel–slippage and integration–error in dead reckoning.

Journal ArticleDOI
TL;DR: In this article, the authors derived emergency stop braking controller, stability enhancement braking controller and a steering controller for low-vehicle and trailer combination vehicles based on Lyapunov theory.
Abstract: Methods for deriving braking controllers and steering controllers for combination vehicles (i.e. low–vehicle and trailer(s) combinations) are described. Central to the development of these controllers is a vehicle model in which the tyre forces are represented as bilinear functions of wheelslip and slipangle. This tyre force representation is valid for tyre forces below saturation levels. It captures the essential trade–off between cornering forces and braking or accelerating forces. Moreover, when the bilinear equations are substituted into the equations of motion, the resulting vehicle model is bilinear. This is important because a large family of control strategies is available for bilinear systems. These control strategies are based on Lyapunov Theory. Many forms of controllers can be derived. In this paper an emergency stop braking controller, a stability enhancement braking controller, and a steering controller are derived. Simulation results are presented to demonstrate the performance of the braking controllers.

Journal Article
TL;DR: In this paper, the authors investigated the design of active suspensions aimed at improving the ride vibration behavior of trucks and incorporating the effects of the flexible frame in the dynamic behaviour by using the Lagrangian approach to obtain the energy equations of the vehicle system motions.
Abstract: The aim of the paper is to investigate the design of active suspensions aimed at improving of the ride vibration behaviour of trucks and incorporating the effects of the flexible frame in the dynamic behaviour. The work is a theoretical study and deals with improvements of the ride comfort, structural acceleration, suspension working spaces and dynamic tyre loads. The road surface profile is considered to be a continuous, random process and is modelled as a filtered white noise excitation. The time delay between the excitation inputs of the vehicle axles is included and modelled using the Pade approximation technique. The FEM (finite element method) and the modal superposition theory have been used to calculate the modal properties of the frame structure. The Lagrangian approach has been applied to obtain the energy equations of the vehicle system motions which result from the well known rigid body modes and from the modal parameters of the frame structure flexibility. Linear stochastic optimal control theory has been used to obtain the optimal active suspension for the truck system based on the full state controller strategy. The performance of the passive system is compared with the performance of the optimal actively controlled systems for two cases, one in which control law accounts for the "preview" effect that the input at the rear is a delayed version of that at the front (referred to as correlated) and one in which the control law does not (uncorrelated). The results show that the modelling technique is a useful design aid for studying the dynamics and control of complex vehicle structures. It is shown that active suspension controllers offer significant improvements over passive systems in acceleration levels, suspension workspace and dynamic tyre load.

Journal Article
TL;DR: In this paper, the authors used the Florida COMPAS computer program to determine the dynamic forces on flexible pavements under various conditions, such as road roughness, suspension type, and vehicle speed.
Abstract: The load applied by trucks on the pavement varies instantaneously due to road roughness, truck speed, suspension type, tyre pressure as well as other factors. Multi–sensor WIM devices are capable of better representing the actual wheel load distribution due to the fact that they capture a large sample size from a variable population. The main objective of the paper is to design the multi–sensor WIM devices for flexible pavements in order to obtain a good estimate of the static vehicle weight. The Florida COMPAS computer program was used to determine the dynamic forces on flexible pavements under various conditions. Nine vehicle types, three suspension types, five levels of road roughness and three speeds were analysed. Dynamic forces were obtained for many combinations of sensor spacings and numbers of sensors. For each case, the sensor spacing which provided the least coefficient of variation of the dynamic impact factor was selected to be the optimum sensor spacing. The minimum number of sensors required to accurately represent the static gross vehicle weight was also determined. The effects of vehicle type, suspension type, pavement roughness and vehicle speed on the minimum number of sensors and the optimum sensor spacing were investigated. The minimum number of sensors and the optimum sensor spacing of multi–sensor weigh–in–motion devices that provide the best estimate of vehicle weight were determined.

Journal ArticleDOI
TL;DR: In this paper, the performance of multiple-sensor weigh-in-motion (WIM) systems was evaluated measuring the load of 95 axles on 21 simulated trucks on most roads.
Abstract: Efforts to measure truck axle weights at normal highway speeds by a single scale installed in the road are ineffective because of the dynamic load variations on the axle. The extended measurement distance required to average out load variations is in conflict with the layout of axles on typical trucks. As a consequence, multiple weight sensors are required. The performance of multiple–sensor weigh–in–motion systems are evaluated measuring the load of 95 axles on 21 simulated trucks. A three–sensor system appears capable of measuring loads on axles with leaf–spring and some air–spring suspensions to an accuracy of 5 to 8 percent on most roads. Measurement of axles with poorly damped wheel–hop resonance modes is much less accurate, with errors on the order of 15 percent.

Journal ArticleDOI
TL;DR: In this article, a concept of articulation damping is analyzed to investigate its influence on the magnitude of yaw and lateral oscillations of the articulated vehicles subject to directional manoeuvres, and a kinematics analysis of the dampers, mounted externally to the articulation mechanism, is performed to derive the lateral damping forces and yaw damping moments acting on the sprung masses.
Abstract: A concept of articulation damping is analysed to investigate its influence on the magnitude of yaw and lateral oscillations of the articulated vehicles subject to directional manoeuvres. A kinematics analysis of the dampers, mounted externally to the articulation mechanism of the articulated vehicle, is performed to derive the lateral damping forces and yaw damping moments acting on the sprung masses. The cornering forces and aligning moments of the radial tyres are characterised by a nonlinear function in normal load, side–slip angle and pneumatic trail. A yaw–plane model of a tractor–semi–trailer, incorporating the kinematics and dynamics of the external dampers and nonlinear cornering characteristics of tyres, is developed to investigate the influence of articulation dampers on the yaw and lateral response of the vehicle. The equations of motion of the vehicle are solved for high–speed lane–change and evasive manoeuvres. The results of the study show that the peak magnitudes of yaw and lateral oscillations, encountered during high–speed directional manoeuvres, can be significantly reduced by the externally mounted articulation dampers.

Journal Article
TL;DR: In this article, a cab suspension design and its dynamic performance when subjected to random road excitation conditions is presented. But their coefficients are time variant and dependent on the objective functions and the constraints used.
Abstract: This paper addresses the cab suspension design and its dynamic performance when subjected to random road excitation conditions. The selected vehicle model is planar and includes a cab with two degrees of freedom, pitch and vertical displacement. The vehicle chassis and trailer are allowed to rotate about their respective axes. The cab suspension is modelled by a set of two linear springs and dampers. However, their coefficients are time variant and dependent on the objective functions and the constraints used. Based on the performance indexes used a suspension design strategy is proposed. The analytical investigation shows that the best driving comfort is obtained when both the angular and vertical acceleration of the cab are optimised. The objective of the cab suspension is two–fold: one objective is to improve ride quality, and the second is to minimise structure stress and fatigue. This paper addresses a comparative study of ride performance, by minimising the angular acceleration of the cab, its vertical displacement, velocity, acceleration, and its rate of change (jerk) using a constrained optimisation technique.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the tractive efficiency of all-wheel-drive vehicles in general and the slip efficiency in particular, focusing on the analysis of the conditions for achieving the optimal slip efficiency.
Abstract: This paper examines the tractive efficiency of all-wheel-drive vehicles in general and the slip efficiency in particular. It focuses on the analysis of the conditions for achieving the optimal slip efficiency. Results of detailed theoretical analyses indicate that all drive wheels operating at the same slip will be the necessary and sufficient conditions for achieving the optimal slip efficiency, if their thrust-slip relationships are either linear or nonlinear with similar characteristics. If the thrust-slip relationships of the drive wheels are nonlinear with different characteristics, the optimal slip efficiency will be reached with the slips of the drive wheels not being equal. The basic findings of this investigation are substantiated with experimental data. The results of this study suggest that the requirement for all drive wheels operating at the same slip provides a reasonable basis for a practical control strategy of an active system to distribute torque (thrust) among the drive wheels to achieve the optimal (or close to the optimal) slip efficiency of all-wheel-drive vehicles under most operating conditions.

Journal ArticleDOI
TL;DR: The dynamic rollover propensity metric known as TTR, namely the Time-To-Rollover, which estimates the time it will take until rollover if the steering is kept at the current level is used here as part of a real-time, hardwarein- the-loop rollover warning indicator system.
Abstract: Developing anti-rollover warning systems and rollover avoidance controllers for heavy commercial vehicles continues to be a focus of research attention as a large number of fatal accidents occur due to the rollover of trucks. The dynamic rollover propensity metric known as TTR, namely the Time-To-Rollover, which estimates the time it will take until rollover if the steering is kept at the current level is used here as part of a real-time, hardwarein- the-loop rollover warning indicator system. A real-time capable and realistic fifth order linear dynamic vehicle model available in the literature and consisting of a combination of roll and yaw dynamics with velocity and steering level scheduled varying parameters is used here. The main contribution of this paper is a hardware-in-the-loop simulator for real-time TTR computation. The warning system developed in the hardware-in-the-loop simulator can then be implemented and tested in a real truck.

Journal ArticleDOI
TL;DR: In this paper, a closed-loop articulated vehicle-driver model, incorporating the lateral position and orientation errors, lateral accelerations of the two units and the rate of steering, is proposed to study the control characteristics of the driver.
Abstract: A closed–loop articulated vehicle–driver model, incorporating the lateral position and orientation errors, lateral accelerations of the two units and the rate of steering, is proposed to study the control characteristics of the driver. The driver model is formulated to minimize the lateral acceleration of vehicle, and the lateral position and orientation errors between the previewed and the actual path of the tractor. The driver's delays and gains associated with the limb movement and muscle activities are represented by the proprioceptive information. Various driver models reported in the literature are reviewed to identify a range of model parameters and their sensitivity to variations in directional manoeuvres and speed. Driver model parameters are identified through minimizing a weighted performance index subject to an array of limit constraints established from the reported data. The proposed model and the identification methodology are validated using the field measured directional response of a seven–axle articulated vehicle under an evasive manoeuvre. The simulation of three double lane change manoeuvres is performed and the influence of vehicle speed on various driver model parameters are discussed. The results of the study may serve as an effective guide to enhance the driver's actions to improve the safety of the driver/vehicle system through improved directional control strategies.

Journal Article
TL;DR: In this paper, the authors used a servo-hydraulic road simulator and a road simulator as a means of measuring dynamic pavement loads to evaluate the road-friendliness of suspensions.
Abstract: Heavy vehicles apply higher than expected loads to road pavements because of dynamic bouncing. Using vehicle–mounted instrumentation and a variety of truck suspensions, TRL has measured these loads on the TRL research track and on public roads. Work is in progress to develop procedures to enable the road–friendliness of suspensions to be assessed. One possibility is to use a servo–hydraulic road simulator and the validation of a road simulator as a means of measuring dynamic pavement loads is the subject of this paper. Several suspensions have been tested on the Volvo Trucks road simulator. The objectives of these tests were to check the accuracy of the vehicle–mounted instrumentation and to test the ability of the road simulator to generate the same dynamic loads as driving the truck along a road of the same profile. Sinusoidal excitation over a range of frequencies was used to check the instrumentation accuracy. It was found that dynamic wheel loads can be measured to 1–2 percent accuracy using shear strain gauges and hub accelerometers. Measurements using bending strain gauges on the axles are less accurate. Measurements of dynamic loads during runs over road profiles measured on the TRL track showed discrepancies between the loads on the track and on the road simulator. In many cases, there appeared to be more roll motion of the vehicle and its axles on the road simulator than on the track. The results and discrepancies are analysed and possible causes for the discrepancies discussed.