Number Of Trailers Research Articles

Absolute joint-angle estimation of Generalised N-Trailer vehicles equipped with incremental encoders using moving horizon estimation

The Generalised N-Trailer (GNT) vehicle is a tool for field operations that optimises harvesting and transportation tasks, offering a highly scalable payload using only one tractor. Precise knowledge of the position and attitude of each segment in the chained vehicle is crucial for the controller’s success during operation. In this study, we propose the use of a Nonlinear Moving Horizon Estimator (NMHE) to estimate the system’s state when the GNT vehicle is equipped with incremental encoders on its joints. A first NMHE serves as a virtual calibration procedure, estimating initial joint angle values and the system’s state using noisy and biased measurements of the joints and the tractor pose. This calibration is performed while the chained vehicle travels along a straight path, whose length is determined by the number of trailers and their geometrical properties. Subsequently, a second NMHE, with fewer optimisation variables and constraints replace the first to effectively reduce the computational burden. Moreover, it treats the incremental encoder measurements as if they were absolute encoders after the initial joint angles have been estimated by the first NMHE. The proposed method is compared against the Extended Kalman Filter (EKF) and validated through simulated and practical real-time experiments, showcasing its effectiveness in achieving precise control and enhancing operational efficiency.

Methodology to estimate logistics costs for vertically transported prefabricated wall panels

Abstract When transporting prefabricated exterior panels vertically, shipping frame types and site conditions affect panel logistics. Thus, it is crucial that project participants estimate the logistics costs considering these factors, which vary by projects, to select the most economic option rapidly and consistently for a specific project in addition to three important objectives of panel logistics (i.e. number of trailers, reshuffling effort, and panel stability). In this study, the authors developed a methodology to generate loading plans for different types of shipping frames and site conditions using both first fit and next fit algorithms and evaluate the cost-related items for the loading plans considering project conditions. To demonstrate the usefulness of the methodology, the authors conducted a case study and compared the logistics costs for three different frame options considering site conditions. The results show that the methodology enables project participants to identify the advantages and disadvantages of different frame options based on given site conditions, which can guide project participants to make informed decisions about the preferred frame option.

A Theoretical Model with Which to Safely Optimize the Configuration of Hydraulic Suspension of Modular Trailers in Special Road Transport

The dimensions and weight of machines, structures, and components that need to be transported safely by road are growing constantly. One of the safest and most widely used transport systems on the road today due to their versatility and configuration are modular trailers. These trailers have hydraulic pendulum axles that are that are attached in pairs to the rigid platform above. In turn, these modular trailers are subject to limitations on the load that each axle carries, the tipping angle, and the oil pressure of the suspension system in order to guarantee safe transport by road. Optimizing the configuration of these modular trailers accurately and safely is a complex task. Factors to be considered include the load’s characteristics, the trailer’s mechanical properties, and road route conditions including the road’s slope and camber, precipitation and direction, and force of the wind. This paper presents a theoretical model that can be used for the optimal configuration of hydraulic cylinder suspension of special transport by road using modular trailers. It considers the previously mentioned factors and guarantees the safe stability of road transport. The proposed model was validated experimentally by placing a nacelle wind turbine at different points within a modular trailer. The weight of the wind turbine was 42,500 kg and its dimensions were 5133 × 2650 × 2975 mm. Once the proposed model was validated, an optimization algorithm was employed to find the optimal center of gravity for load, number of trailers, number of axles, oil pressures, and hydraulic configuration. The optimization algorithm was based on the iterative and automatic testing of the proposed model for different positions on the trailer and different hydraulic configurations. The optimization algorithm was tested with a cylindrical tank that weighed 108,500 kg and had dimensions of 19,500 × 3200 × 2500 mm. The results showed that the proposed model and optimization algorithm could safely optimize the configuration of the hydraulic suspension of modular trailers in special road transport, increase the accuracy and reliability of the calculation of the load configuration, save time, simplify the calculation process, and be easily implemented.

Capacity planning in in-plant milk run system

This study investigates material flow in in-plant milk run system in which a tugger train transports materials and parts from a warehouse to several workstations in one route. The focus of the paper is to deal with train capacity problems due to the dynamic nature of workstations demand where several unique product models needing unique demand requirements are assembled. Dynamic train cycle time, early loading, and minimising extra number of trailers are the tools used in this study to minimise the needed train capacity keeping the area beside stations not to be crowded with bins more than its capacity. This is done step by step using four integer programming models. Randomly generated instances showed that combining the three tools results in great decrease for the extra needed number of trailers, but small decrease in the maximum needed number of trailers.

Kinematics and Motion Planning of the Multi-Bar System

This paper studies a generalization to 3D space of the planar system composed of a tractor pulling a number of trailers, called the multi-bar system. Assuming a natural coordinate description of the system, its kinematics equations are derived in the form of a driftless control system with three controls. The motion planning problem is stated, and solved by means of a Jacobian algorithm resulting from the endogenous configuration space approach. Solutions of example motion planning problems are obtained by numeric computations.

Effects of multiple axles on the lateral dynamics of multi-articulated vehicles

This paper describes an analytical study of the lateral dynamics of multi-articulated vehicles with multiple axles. A linear planar model of vehicle dynamics is adopted for multiple-axle vehicle combinations with an optional number of trailers. Two tractor and double-trailer combinations are examined for their directional stability and response. Non-oscillatory stability and steering sensitivity in steady-state turning and lane changing are analysed using a stability factor of multiple-axle vehicle combinations. Off-tracking in the steady-state turning of multiple-axle vehicle combinations is also analysed. Numerical calculations for oscillatory stability, steering sensitivity, and off-tracking are presented for multiple-axle vehicle combinations.

Fast Track Construction of Viaducts of Bangalore–Hosur Elevated Expressway

The project of Bangalore–Hosur elevated expressway comprises 10 km of elevated viaduct, a complex traffic interchange, two flyovers, several vehicular underpasses and pedestrian underpasses (VUPs and PUPs), as well as ground level roads. The owners laid emphasis on the riding quality and made it mandatory for the contractor and designer to keep the spacing of the expansion joints at a minimum of 262 m. The elevated viaduct has been constructed using a precast segmental continuous superstructure over the spans (29 m + 6 × 34 m + 29 m = 262 m). The sharply curved interchange superstructure has been conceptualised as a cast-in situ reinforced cement concrete (RCC) voided slab with spans ranging between 20 and 35 m. The two flyovers comprise a continuous girder-slab superstructure incorporating precast post-tensioned girders. The VUPs and PUPs have been constructed using the box pushing method. All earth-filled approach ramps have been conceptualised as reinforced soil embankments.The eight span continuous superstructure of the elevated viaduct was constructed in eight stages comprising 1¼ of span, ¾ + ¼ span, ¾ + ¼ span, ¾ + ¼ span, ¾ + ¼ span, ¾ + ¼ span, ¾ + ¼ span, and ¾ span. The analysis and design had to carefully simulate a structural model in order to account for stage wise prestressing, hyperstatic effects and creep redistribution, apart from the applicable primary loading. Where the stilted approach ramps joined the main viaduct, the expansion joints of the two structures were so aligned to have the same longitudinal expansion and contraction, such that the expansion joint material along the longitudinal joint between the two structures behaved satisfactorily. Speed of erecting the single-cell box superstructure for each span of the 262 m long module was about 3½ days. As the single box-girder carried two carriageways, the speed was about 1¾ days per carriageway span. The main attributes to the speed of construction were the use of wireless remote controlled launching girder, matching speed of production of precast segments that were produced using short bench method, and the prefabricated reinforcement used to speed up the precasting process. An adequate number of trailers were employed for transportation.

Analysis of large truck crash severity using heteroskedastic ordered probit models

Long-combination vehicles (LCVs) have significant potential to increase economic productivity for shippers and carriers by decreasing the number of truck trips, thus reducing costs. However, size and weight regulations, triggered by safety concerns and, in some cases, infrastructure investment concerns, have prevented large-scale adoption of such vehicles. Information on actual crash performance is needed. To this end, this work uses standard and heteroskedastic ordered probit models, along with the United States’ Large Truck Crash Causation Study, General Estimates System, and Vehicle Inventory and Use Survey data sets, to study the impact of vehicle, occupant, driver, and environmental characteristics on injury outcomes for those involved in crashes with heavy-duty trucks. Results suggest that the likelihood of fatalities and severe injury is estimated to rise with the number of trailers, but fall with the truck length and gross vehicle weight rating (GVWR). While findings suggest that fatality likelihood for two-trailer LCVs is higher than that of single-trailer non-LCVs and other trucks, controlling for exposure risk suggest that total crash costs of LCVs are lower (per vehicle-mile traveled) than those of other trucks.

Cost analysis of the unloader queueing system with a single unloader subject to breakdown with two types of trailers

The main purpose of this paper is to develop a cost model for the unloader queueing system with a single unloader subject to breakdown with two types of trailers. The optimum value of number of trailers (taking two types together) is determined in two types of systems such that cost function per trailer per unit time is minimum. In type one system, the unloader can breakdown only when there is at least one trailer in the system. In type two system, the unloader can breakdown even when there is no trailer in the system. Related measures and parameters are evaluated and cost function is determined. Numerical evaluation is also given.

A two-phase tabu search approach to scheduling optimization in container terminals

An optimization model for scheduling of quay cranes (QCs) and yard trailers was proposed to improve the overall efficiency of container terminals. To implement this model, a two-phase tabu search algorithm was designed. In the QCs scheduling phase of the algorithm, a search was performed to determine a good QC unloading operation order. For each QC unloading operation order generated during the QC’s scheduling phase, another search was run to obtain a good yard trailer routing for the given QC’s unloading order. Using this information, the time required for the operation was estimated, then the time of return to availability of the units was fed back to the QC scheduler. Numerical tests show that the two-phase Tabu Search algorithm searches the solution space efficiently, decreases the empty distance yard trailers must travel, decreases the number of trailers needed, and thereby reduces time and costs and improves the integration and reliability of container terminal operation systems.

Cost analysis of the unloader queueing system with a single unloader subject to breakdowns

In this paper, we deal with an unloader queueing model in which N identical trailers are unloaded by a single unloader. We consider two different types of a single unloader, which are subject to breakdowns. In type 1, the unloader can break down only when there is at least one trailer in the system, while in type 2, the unloader can break down even if no trailers are in the system. Analytic closed-form solutions of the unloader queueing system are derived. A cost model is developed in order to determine the optimal value of the number of trailers to be assigned to the unloader for both types. Under the optimal operating condition, numerical results are presented in which several system performance measures are evaluated based on assumed numerical values given to the system parameters. Sensitivity analysis is also investigated.

Dynamic Yard Operations in a Multi-user Container Terminal

We introduce in this paper a multi-user terminal system for a container port to reduce the cargo handling cost. Due to the complexity in that system, an efficient yard operation must be desired. Then we propose a dynamic yard operation with trailers in the terminal. By the dynamic operation, the number of trailers can be reduced by 10% while keeping the cycle time of a quay crane the same as one with a conventional operation. Further the average handling time per ship can be 2 hours less with the same number of trailers as in the conventional one.

Cost analysis of the R-unloader queueing system

This paper deals with an unloader queueing model in which N identical trailers are unloaded by one or more unloaders. Theoretical solutions are obtained with the assumption of negative exponential distributions for trip times, unloading times, and finishing times. A cost model is developed to determine the optimal number of trailers. In order to evaluate the model robustness, simulation models are developed for three different distributions, exponential, second-order Erlang, and triangular. We demonstrate, through simulation results, that the unloader queueing model is sufficiently robust to the variations of probability distributions.

Accident rates for heavy truck-tractors in Michigan

Accident rates of heavy truck-tractors are modelled using log-linear methods. The accident data used are a census of truck-tractor involvements in Michigan from May 1987 to April 1988. Travel data used to calculate the rates were produced by a survey of truck-tractors in Michigan covering the same time period. Both the accident and travel data were limited to Michigan-registered tractors operating in Michigan. Log-linear models of casualty and property-damage-only accident rates were developed using number of trailers, road type, area type, and time of day as predictor variables. Overall, differences between tractors with one and two trailers were not significant. Tractors with no trailers (bobtails) have significantly higher accident rates. Characteristics of the operating environment were found to have larger effects on the accident rate than tractor configuration (except for the bobtail). Rates varied by a factor of up to 6.8, depending on the road type. Casualty accident risk at night was 1.4 times the risk during the day. The risk of a casualty accident in rural areas was 1.6 times that of urban areas.

Dynamical behavior of a tractor-semitrailer combination near the boundary of the domain of stability

A distinctive feature of rubber-tired tractor--trailer trucks ("automotive trains") is the capability of relative rotation of the tractor and trailer(s). This feature increases the maneuverability of the combination vehicle in comparison with a single truck of the same length and thereby decreases the turning radius of the vehicle without skidding or wheel detachment. However, combination vehicles suffer a loss of stability of straight-ahead motion, and an increase in the number of trailers diminishes the possibilities of analytical investigation, because each additional trailer in the case of rubber-tired vehicles adds at least one new degree of freedom to the vehicle. The only exception is the case of perfectly rigid wheels, which create the classical condition of nonholonomic constraints: The number of degrees of freedom of such a vehicular combination in planeparallel motion is equal to two, now matter how many trailers are pulled. The first studies of the dynamical behavior of a tractor-semitrailer combination was aimed at ensuring the stability of straight-ahead motion. In cases that are not Lyapunov critical, the problem is known to be solved on the basis of a linearized approximation of the equations of perturbed motion. The practical significance of the problem has stimulated a great many relevant investigations in our own and other countries. Its solution currently encompasses results of a general nature (e.g., an expression tbr the critical velocity and turning radius of a combination with an arbitrary number of trailers [5]) and results pertaining to semitrailer and double-trailer trucks [6, 7]. In particular, the boundaries of the stability domain have been established in the space of parameters of a tractor--semitrailer pair [6]. These boundaries correspond to a simple zero eigenvalue or a pair of nonmultiple, purely imaginary eigenvalues of a matrix of equations in variations when all other eigenvalues have negative real parts. Cases of multiple roots of the characteristic equation have not been observed, i.e., the investigated real linear system is decomposed into a direct product of oneand two-dimensional systems. The dynamical behavior of the system near a stability boundary depends on the type of stability of the boundary [4]. The present article is devoted to the solution of this problem and a discussion of the implications of the solution in regard to a tractor--semitrailer combination. We note that the flutter--divergence bifurcations of a tractor--semitrailer in the vicinity of a point in parameter space where the characteristic equation has one zero root and a pair of purely imaginary roots have been analyzed previously in a series of papers [12-t5]. The mathematically related problem of the vibrations of a double pendulum bui!t-in at one end and loaded by a nonconservative following force has also been investigated [10, 11].