Tractor Semitrailer Research Articles

Safety Benefits of Stability Control Systems for Tractor–Semitrailers Estimated with Hardware-in-the-Loop Simulation

This research estimated the safety benefits of electronic stability control systems for tractor–semitrailers by using hardware-in-the-loop (HiL) simulation. The HiL system used in this study consisted of a pneumatic tractor–semitrailer braking system and a truck simulation engine, TruckSim. Additionally, the Bendix electronic stability control system was integrated with the HiL system for the evaluation. The study evaluated the performance of the stability control system by using the HiL platform for a portion of the rollover and loss-of-control crashes selected from the database of the Large Truck Crash Causation Study. Subsequently, the evaluated performance was combined with the effectiveness rated by the expert panel at the University of Michigan Transportation Research Institute to calculate the total crash prevention ratios. Finally, this study estimated crash reductions and cost benefits. It provides lessons learned to researchers and practitioners through the course of evaluation procedures.

Handling Stability of Tractor Semitrailer Based on Handling Diagram

Handling instability is a serious threat to driving safety. In order to analyze the handling stability of a tractor semitrailer, a handling diagram can be used. In our research, considering the impact of multiple nonsteering rear axles and nonlinear characteristics of tires on vehicle handling stability, the handling equations are developed for description of stability of tractor semi‐trailer. Then we obtain handling diagrams so as to study the influence of driving speed, loaded mass, and fifth wheel lead on vehicle handling stability. The analysis results show that the handling stability of a tractor semi‐trailer when the tractor has two nonsteering rear axles is better than that when the tractor has only one nonsteering rear axle. While the stability in the former case is slightly influenced by driving speed and loaded mass, the latter is strongly influenced by both. The fifth wheel lead is found to only slightly influence handling stability for both tractor semi‐trailers. Therefore, to ensure the driving safety of tractor semi‐trailers when the tractor has only one nonsteering rear axle, much stricter restraints should be imposed on driving speed, and the loaded mass must not exceed the rated load of the trailer.

Optimisation of whole body vibration analysis for suspended cabin tractor semitrailer

This work has been conducted to find out the health risk associated with suspended cabin tractor semi-trailer driving work. Suspended cabin tractor semi-trailer drivers are exposed to whole body vibration (WBV) during their work. Some drivers suffer from low back pain caused by vibration. The practical significance of applying suspended cabin type of tractor semi-trailer was tested at different road conditions, different speeds as well as different load conditions for comfortable driver seat interface (x, y, z axes) and the ride comfort parameters have been prioritised using Taguchi’s L27 orthogonal array. Genetic algorithm (GA) is used to optimise the whole body vibration of suspended cabin tractor semi-trailer drivers. The practical significance of applying GA to whole body vibration of suspended cabin tractor semi-trailer has been validated by means of computing the deviation between predicted and experimentally obtained vibration different measurement conditions.

Analyzing Investments Needed to Support Oil and Gas Production and Distribution

The purpose of this study was to forecast road investment needs in the oil- and gas-producing counties of North Dakota over the next 20 years in light of its expected population growth and the growth of oil and gas production. With the essential objective of quantifying the additional investments necessary for efficient year-round transportation of oil while providing travelers with acceptable roadway service, the study focused on roads owned or maintained by local governments, e.g., counties and townships. Impacts and funding needs were analyzed for three types of roads: paved, gravel, and graded and drained. The analysis was based on three main data sources: oil production forecasts, traffic data, and county road surveys. The forecast output of wells was routed over the road network to pipelines, with a detailed geographic information system model in which oil movements were represented as equivalent tractor–semitrailer trips that follow least-cost paths. The projected inputs of sand and water and the outbound movements of salt water to disposal sites were similarly routed. These predicted inbound and outbound movements were accumulated for each impacted segment. Movements of specialized equipment were included in the analysis. Several types of potential road improvements, including reconstruction and structural overlays, were analyzed in this study. The model developed in this research can be transferred to other states where new oil fields are opening and analysis is required for additional investment in highway infrastructure.

Nonlinear Dynamics and Lateral Stability of Tractor Semi-trailer Vehicle

Since the lateral dynamics of a tractor semi-trailer vehicle is rather complex resulting from the large variations of the load and the centre of mass(CM) of the trailer,it becomes difficult to design the stability control system.The nonlinear dynamics and the lateral stability of the tractor semi-trailer vehicle is investigated.The relations of the lateral stability,equilibrium bifurcation and Hopf bifurcation with the load scenarios are analyzed in detail.Combining the means of understeer gradient and damping ratio,the lateral instability and mechanisms are discussed.The results reveal that nonlinear dynamical phenomena such as saddle-node bifurcation,Hopf bifurcation and homoclinic orbit are identified in critical cornering situations.For a typical tractor semi-trailer vehicle,jackknife caused by the sideslip of the rear axle of the tractor is the primary way to lead the vehicle to lateral instability.Trailer oscillation which is much related to Hopf bifurcation generally occurs when the load weight is considerably large and the trailer CM is much near to the rear axle of the trailer.Further,trailer oscillation is prone to further develop to jackknife and trailer swing often causes the whole vehicle including the tractor to sideslip with jackknife occurring simultaneously.Rather satisfying control performance is expected to be obtained by selecting the tractor yaw rate and trailer slip angle as the control variables to design vehicle stability control system.

Whole Body Vibration Analysis for Drivers of Suspended Cabin Tractor Semitrailer

This work has been conducted to find out the health risk associated with driving suspended cabin tractor semitrailer. Suspended cabin tractor semitrailer drivers are exposed to whole body vibration during their work. Some drivers suffer from low back pain caused by vibration. However, due to the lack of investigations there is no evidence of relation between the whole body vibration from the means of conveyance and low back pain. The practical significance of applying suspended cabin type of tractor semitrailer was tested at different road conditions as well as in both loaded and unloaded conditions at different speeds for comfortable driver seat interface (x—longitudinal, y—transverse, and z—vertical axes). Average running root mean squared weighted accelerations for suspended cabin tractor semitrailer were between 0.5624 and 1.4368 m/s2 at the driver seat interface in the translational axes. The acceleration suspended cabin tractor semitrailer drivers are prove to exceed the upper exposure limit of 8-h work day as outlined in ISO 2631 when they work continuously.

A study on the asynchronous brake lock-up of a statically indeterminate tractor with an air suspension

The paper aims to resolve the practical problems of asynchronous brake lock-up which acts on the wheels of statically indeterminate tractors with an air suspension. First, two kinds of deflection model are calculated, both of which are under the combined effect of the brake force and the vertical force. One model considers the leaf spring suspension that is mounted on the front axle, and the other considers the air suspensions that are mounted on both the midlift axle and the drive axle. Second, a 12-degree-of-freedom braking force distribution model of the statically indeterminate multi-axle tractor–semitrailer is constructed on the basis of the foregoing preparation. Third, the ideal braking forces of each axle in the model are simultaneously calculated and the actual braking forces of each axle are measured by road tests. The curves of the ideal and the actual braking force distribution ratios at different brake rates are described. The contradistinctive outcome indicates that the excessive braking force of the midlift axle results in a premature brake lock-up, which is the main reason why wheels lock asynchronously. Finally, because of the analysis of the distribution ratios of the ideal and the actual braking forces, the paper outlines how to redesign the braking force distribution of the tractor–semitrailer according to ECE R13, SAE J992b, and JASO C514. The paper also proposes a definition of and calculational method for the fitting degree (FD), and the FD of the midlift axle is improved from 61.2 per cent to 91.8 per cent. Compared with the original tractor–semitrailer, not only is the actual braking force distribution more reasonable but also the brake stability is improved.

Wind tunnel tests on heavy road vehicles: Cross wind induced loads—Part 2

The sensitivity of heavy road vehicle aerodynamic coefficients to different testing parameters (scenario, vehicle type and turbulence intensity) is experimentally evaluated in this paper through wind tunnel experiments. The first part of the paper has investigated the aerodynamic loads (both stationary and non-stationary) acting on a high-sided lorry (VAN) in a flat ground scenario. The mean aerodynamic coefficients, the flow pattern around the vehicle and the aerodynamic admittance function have been assessed and compared for different wind turbulence conditions (boundary layer simulations). The present paper instead investigates the influence of the infrastructure scenario (flat ground, embankment, single and double viaduct), of the exposition (upwind or downwind) and of a trailed unit on the aerodynamic loads acting on the vehicle. Moreover, the mean aerodynamic coefficients and the aerodynamic admittance function of the high-sided lorry considered in the first part are compared with the ones of other heavy vehicles (tank truck, tractor–semitrailer combination and tractor–trailer combination) to assess the influence of the vehicle geometry.

Jackknife Control on Tractor Semi-Trailer during Emergency Braking

Emergency braking on a low coefficient of friction or split-mu road surface, the semi-trailer may push the tractor from behind until it spins round and faces backwards, and a jackknife accident occurs. In this paper, the tractor semi-trailer kinematics was analyzed and a 3-dof of tractor semi-trailer model was used to design a state observer to estimate the articulation angle. To avoid a jackknife, the four-channel ABS which can produce maximum braking force will be switch to three-channel ABS according the estimated articulation angle. The virtual prototyping simulation results show that the jackknife control system can improve the tractor semi-trailer lateral stability under emergency braking and shorten the stop distance dramatically on split-mu road surface at high speed.

Stability Control on Tractor Semi-Trailer during Split-Mu Braking

Handling behaviour of articulated vehicles combination is more complex and less predictable than that of non-articulated vehicles. It is usually difficult for drivers to maneuver a tractor semi-trailer during high speed emergency braking on split-mu road surface. Braking on this type of road surface, the conventional anti-lock braking systems will cause the vehicle deviate from the desired direction, or overmuch stopping distance. In this paper, a 3-dof of tractor semi-trailer model was used to produce desired yaw rates which were compared with actual yaw rates. An active front steering control and four-channel ABS were integrated to improve the tractor semi-trailer lateral stability while braking on split-mu road surface, which will produce maximum braking force. A full function tractor semi-trailer model was built and assembled in multi-body dynamics software, and the dynamic analysis was performed on split-mu road surface. The simulation results show that the integrated system can improve the tractor semi-trailer lateral stability under braking on split-mu road surface.

Parameter measurement for heavy-vehicle fuel consumption modelling

A mathematical model is developed to predict the energy consumption of a heavy vehicle. It includes the important factors of heavy-vehicle energy consumption, namely engine and drivetrain performances, losses due to accessories, aerodynamic drag, rolling resistance, road gradients, and driver behaviour. Novel low-cost testing methods were developed to determine engine and drivetrain characteristics. A simple drive cycle was used to validate the model. The model is able to predict the fuel use for a 37 t tractor–semitrailer vehicle over a 4 km drive cycle within 1 per cent. This paper demonstrates that accurate and reliable vehicle benchmarking and model parameter measurement can be achieved without expensive equipment overheads, e.g. engine and chassis dynamometers.

High-speed optimal steering of a tractor–semitrailer

A high-speed optimal trailer steering controller for a tractor–semitrailer is discussed. A linear model of a tractor–semitrailer with steered trailer axles is described, and an optimal trailer steering controller is introduced. A path-following controller is derived to minimise the path-tracking error in steady-state manoeuvres using active trailer steering. A roll stability controller is introduced by adding the lateral acceleration of trailer centre of gravity as another objective in the steering controller, so as to improve roll stability in transient manoeuvres. A strategy to switch between these two control modes is demonstrated. Simulation results show that the steering controller can ensure good path tracking of articulated vehicles in steady-state manoeuvres and improve roll stability significantly in transient manoeuvres, while maintaining the path-tracking deviation within an acceptable range. Tests with an experimental tractor–semitrailer equipped with a high-bandwidth active steering system validate the controller design and simulation results. The roll stability controller reduces the measured rearward amplification by 27%.

Parameter and state estimation for articulated heavy vehicles

This article discusses algorithms to estimate parameters and states of articulated heavy vehicles. First, 3- and 5-degrees-of-freedom linear vehicle models of a tractor semitrailer are presented. Vehicle parameter estimation methods based on the dual extended Kalman filter and state estimation based on the Kalman filter are presented. A program of experimental tests on an instrumental heavy goods vehicle is described. Simulation and experimental results showed that the algorithms generate accurate estimates of vehicle parameters and states under most circumstances.

Prevention of Tractor–Semitrailer Rollovers: Effectiveness of Electronic Stability Control Systems

This study estimated the effectiveness of electronic stability control systems and roll stability control systems in preventing rollovers of heavy-truck tractor–semitrailers. The study combined hardware-in-the-loop simulation with the analysis of independent crash data sets. Engineering and statistical techniques were used to estimate the probable safety benefits of stability control technologies for five-axle tractor–semitrailers. The conventional approach for assessing the safety benefits of vehicle technologies was to analyze crash data sets containing data on the safety performance of vehicles equipped with the technology of interest. Because the deployment of the stability technologies for large trucks was in its infancy, national crash databases did not yet have a sufficient amount of factual data that could be directly linked to the performance of the technologies. Therefore a novel method of examining the potential benefits of these systems was used. This study focused on untripped vehicle rollovers in curves through the examination of crash scenarios that would be likely to benefit from the technologies; the probable effectiveness of each technology was estimated. The analysis in this study did not have the advantage of examining representative crash data sets that contained identifiable data from vehicles equipped with the technologies. Therefore, the analysis was based on probable outcome estimates derived from hardware-in-the-loop simulation, field test experience, and expert panel assessment, and these methods were used to estimate the safety benefits from the national crash data population.

Rollover Prediction and Control in Heavy Vehicles Via Recurrent High Order Neural Networks

Abstract In this paper, a predictor is developed in order to estimate roll angle and lateral acceleration for tractor-semitrailers. Based on this prediction, an active control system is designed to prevent rollover for these vehicles. In order to develop this control structure, a high order recurrent neural network is used to model the unknown tractor semitrailer system; a learning law is obtained using the Lyapunov methodology. Then a control law, which stabilizes the reference tracking error dynamics, is developed using Control Lyapunov Functions and the inverse optimal control approaches. Via simulations, the control scheme is applied to the speed-only and speed-yaw rate trajectory tracking in atractor-semitrailer during a cornering situation.

Evaluation of Full and Partial Stability Systems on Tractor Semi Trailer Using Hardware-in-the-Loop Simulation

Evaluation of Full and Partial Stability Systems on Tractor Semi Trailer Using Hardware-in-the-Loop Simulation

Factors influencing the energy consumption of road freight transport

Key factors that influence the energy consumption of heavy goods vehicles are investigated. These factors include engine efficiency, aerodynamic drag and rolling resistance, vehicle configuration (number of vehicle units), traffic congestion, speed, payload factors, and the use of regenerative braking. An accurate, validated model of the fuel consumption of a 38 tonne tractor-semitrailer vehicle is used as a basis to derive fuel consumption models of a number of other vehicle configurations. These models included a rigid four-axle truck with maximum gross vehicle mass (GVM) of 26 tonnes; a six-axle tractor semitrailer with GVM of 44 tonnes, with and without regenerative braking; a ‘B-double’ with GVM of 60 tonnes; and an ‘A-double’ with GVM of 82 tonnes. These vehicle models were driven over a simple hypothetical drive cycle with a fixed maximum speed and varying numbers of stops in a 10 km stretch of road. It is concluded that: (a) improving engine efficiency, unladen mass, rolling resistance, and aerodynamic drag can yield relatively small improvements in fuel consumption, compared with other factors; (b) larger vehicles are always significantly more energy-efficient than smaller ones when fully loaded; (c) transferring freight from articulated vehicles to smaller rigid vehicles for urban deliveries typically increases fuel consumption by approximately 35 per cent; (d) running vehicles partially loaded can increase the energy per unit freight task by up to 65 per cent; and (e) under urban start—stop conditions, the use of regenerative braking systems can reduce heavy vehicle fuel consumption by 25–35 per cent.

Lateral Stability Control Design for Tractor Semitrailer Based on Virtual Prototyping

Tractor semitrailers on high speed obstacle avoidance under emergency are likely to arise rollover or jack-knifing, which are serious risks for motorists. A dynamic stability analysis model of a three-axle tractor semitrailer vehicle is developed using the application tool. The linearized vehicle model is utilized to predict the dynamics state of the tractor semitrailer built in multibody dynamics simulation software. The lateral stability simulation for yaw rate following and anti-rollover has been performed on the dynamic model based on virtual prototyping. The results show that the lateral stability control based on tractor semitrailer proposed in this paper can stabilize the tractor semitrailer, rollover and jack-knifing can be prevented to a large extent.

Vehicle Dynamics Control for Tractor Semitrailer Lateral Stability

Rollover and jack-knifing of tractor semitrailer on high speed obstacle avoidance under emergency are serious threats for motorists. A tractor semitrailer model was built with multi-rigid-body method in this paper. The steering performance of tractor semitrailer has been analyzed, as well as the stability control theory, including yaw rate following, anti-rollover. The dynamics simulation for yaw rate following and anti-rollover has been performed on the dynamic tractor semitrailer. The results show that the vehicle dynamics control proposed in this paper can stabilize the tractor semitrailer, rollover and jack-knifing are prevented and the tractor semitrailer more accurately follows the driver's desired path.

Development and validation of a modular simulation model for commercial vehicles

In this paper a modular truck semi-trailer model is developed in the multi-body toolbox SimMechanics, which is part of MATLAB/Simulink. It can be used to analyse a wide range of active control solutions (anywhere in the model), as well as the influence of passive vehicle modifications. As the model is modular, it is relatively easy (compared to conventional multi-body software packages) to modify or replace any of the components as well as the number and type of trailer axles. The model is validated using a wide range of measurement data obtained from measurements on a real air sprung tractor semi-trailer.