Tractor Semitrailer Research Articles

Research on Active Trailer Steering Control Strategy of Tractor Semitrailer under Medium-/High-Speed Conditions

Abstract: The study proposes an active trailer steering control method for tractor semitrailers to promote the path tracking effect of the trailer portion as well as lateral stability during lane changing. Firstly, a simplified model of a tractor semitrailer is constructed, and the MAP map is formed based on the genetic algorithm for the identification of the key parameters, which improves the model’s accuracy. Then the tractor and trailer’s yaw rate and sideslip angle at CG are tracked as the control objective and the trailer angle distribution strategy is given. Then the LQR-based corner controller is designed to control the steering actuators of each axle of the trailer. Finally, the effectiveness of the designed control strategy is verified based on the Trucksim/Simulink joint simulation platform and the semi-physical HiL test platform. The simulation results show that the designed controller can effectively improve the path tracking effect of the tractor and the trailer, and at the same time, the lateral stability parameters of the tractor and the trailer are also significantly improved, which improves the driving stability of the tractor semitrailer.

Study on lateral stability of distributed drive electric tractor semi-trailers under low adhesion road conditions

Study on lateral stability of distributed drive electric tractor semi-trailers under low adhesion road conditions

Safe speeds for a heavy articulated vehicle when passing a floating bridge tower under crosswind

This paper recommends safe speeds for a heavy articulated vehicle when passing by Bjørnafjorden floating bridge tower under two constant crosswind speeds (65 km/h and 100 km/h). The analysis is based on the tractor-semitrailer (TS) model with fifth-wheel (FW) coupling in roll and free in yaw. Comparison of safe speeds assessments has been made with two TS models differ in FW coupling. Aerodynamic forces and moments for TS models as function of their position relative to the bridge tower and time were computed using Computational Fluid Dynamics (CFD) simulations. For TS model coupled in roll and free in yaw, no rollover risk is noticeable for both crosswind excitations. For TS model free in roll and in yaw, roll-over risk is noticeable at lower vehicle velocities (at 36 km/h and 54 km/h). TS with rigid connection in FW stays in the traffic lane for every considered vehicle velocity. TS model which is roll and yaw moment free in the FW overestimates rollover risk assessment at lower vehicle velocities. TS model with rigid connection in the FW underestimates traffic lane departure assessment at higher vehicle velocity. Appropriate mathematical modelling of a heavy articulated vehicle that considers tractor and semitrailer units as two separate bodies coupled in roll and free in yaw is of importance for accurately assessing safe speeds when a vehicle passing by the bridge tower.

A Simulation Approach to Determine Dynamic Rollover Threshold of a Tractor Semi-Trailer Vehicle during Turning Maneuvers

A Simulation Approach to Determine Dynamic Rollover Threshold of a Tractor Semi-Trailer Vehicle during Turning Maneuvers

Bi-level path tracking control of tractor semi-trailers by coordinated active front steering and differential braking

In recent years, autonomous tractor semi-trailers have been considered a promising solution for transportation on highways, ports, and large logistics centers to improve safety and efficiency. However, due to the complicated dynamics introduced by articulation structure, there are still challenges in achieving high-precision path tracking and stability control for tractor semi-trailers, especially in critical scenarios. In this work, a bi-level path tracking control scheme for the autonomous tractor semi-trailer is proposed. At the higher level, a robust model predictive controller coordinating active front steering and differential braking is devised for addressing path tracking, stability control and robustness for an autonomous tractor semi-trailer. At the lower level, incorporating a logic switching mechanism, the designed optimal braking torque distribution module and the PID-based longitudinal control module prioritize the implementation of differential braking and target speed tracking. Simulation results demonstrate that the proposed control strategy offers remarkable path tracking performance in three designed testing scenarios.

Ensuring the safety of animals and agricultural products by increasing the stability of the tractor semi-trailer

Ensuring the safety of animals and agricultural products by increasing the stability of the tractor semi-trailer

Rollover Prediction and Control Strategy Based on Experiment for Tractor Semitrailer Fitted with Hydraulically Interconnected Suspension

Rollover Prediction and Control Strategy Based on Experiment for Tractor Semitrailer Fitted with Hydraulically Interconnected Suspension

Analysis of vehicle path tracking ability and lateral stability on a floating bridge under a crosswind

The reconstructed route E39 along the west coast of Norway will provide efficient local and regional transportation for people and goods. Efficient transportation implies safety measures exist, e.g., driving speed limits for adverse weather condition. This is especially important for structures in open areas, such as long-span bridges. This paper investigates the path tracking ability and lateral stability of two vehicle types – a tractor-semitrailer (TS) and a sport utility vehicle (SUV) – on the Bjørnafjorden floating bridge considering a 1-year storm condition. At a speed of 108 km/h, the TS experiences a roll-over risk, and at a speed of 90 km/h, it frequently leaves the traffic lane. At the highest speed, the SUV wheels do not lose contact with the bridge deck, but the vehicle does leave the traffic lane. This implies that a TS driver requires more vehicle handling effort over the floating bridge than an SUV driver. Results suggest that a TS can safely enter the bridge at a low speed (36 km/h) and then accelerate to 72 km/h after travelling 2 km. An SUV entering at a speed of 90 km/h and accelerating to 108 km/h after travelling 0.5 km was found to be safe.

Study on Effects of Road Conditions on the Lateral Instability of Tractor Semitrailer Vehicle during Turning Maneuver

Instability of vehicle can be defined as an unexpected response maneuver that induces disturbance, occurring in the ground plane. This can include the longitudinal, lateral, pitch, yaw, roll direction, or their combinations. Many tractor semitrailer vehicle accidents can be caused by lateral instabilities which may be classified into two types: rollover and yaw instability. Rollover occurs when centrifugal forces imposed on the vehicle during a maneuver exceed the rollover threshold of the vehicle. Yaw instability often occurs in tractor semitrailer vehicles during turning maneuver on the road with low friction coefficient. The yaw instability is shown by the loss of motion trajectory or Jack-knife. This paper establishes a dynamic model of tractor semitrailer vehicle, based on Multi-Body System Method analysis and Newton-Euler equations with Burckhardt’s tire model. This model is applied to evaluate the effect of road conditions on lateral instability of the tractor semitrailer vehicle during turning maneuver. The results can serve as the basis for determining the early warning and controlling the lateral instability of tractor semitrailer vehicle with the dynamic model.

Yaw Stability Analysis of a Tractor Semitrailer Using Yaw Plane Model

Lateral dynamics of a road vehicle refers to its directional control and stability. Bicycle model is the classical proven model for this study. This paper presents a4 degrees of freedom mathematical model, representing a three-axle tractor semitrailer, to investigate its yaw stability in combined cornering and braking manoeuvres. The equations of motion governing the system are derived using Newtonian mechanics and then converted into a state space form for simulation. A non-linear tire model and a load transfer model are implemented to accurately incorporate the effect of braking on yaw stability. In the first step, steady state analysis is performed to determine the variation of steady state gain characteristics such as yaw velocity gain and articulation angle gain for different loading conditions of the vehicle. Yaw response characteristics such as articulation angle, articulation rate, lateral velocity and yaw rate are simulated in MATLAB. In the second step, the directional responses of the vehicle during jackknifing and trailer swing are studied by performing simulations under wheel lock-up condition on different axles and are compared with the no-wheel-lock up condition. Eigen value analysis is used to observe the variation in stability under different simulation conditions. Finally in the third step the effect of increasing forward speed on the stability is also simulated.

An improved smooth shift strategy for clutch mechanism of heavy tractor semi-trailer automatic transmission

The shift quality of an automatic transmission (AT) has a significant impact on the driving comfort, fuel economy and service life of heavy tractor semi-trailer. Existing research on shift control in such vehicles is scarce and improved shift quality can contribute to development of the transportation industry. In this study, a shift strategy using a robust tracking control algorithm for AT heavy tractor semi-trailers is proposed. A high-order dynamic model with clutch actuator and planetary gear is proposed for the heavy tractor semi-trailers. Based on the clutch slip speed, a robust control strategy consisting of feedforward, feedback, and disturbance controllers is designed to provide precise control and quick response of shift actuator. Experimental data is compared with the numerical results to validate the reliability of shift control strategy. Besides, this study analyses the influence of hitch articulation angle and steering angle of semi-trailer on disturbance torque and verifies the efficacy of the proposed controller by comparing its performance to those of a traditional proportion integral differential controller and an adaptive control method. Results show that the proposed controller is superior to the traditional controller considering the tracking error, shift time, friction work, and significantly improves shift quality.

Evaluation of Dynamic Load Reduction for a Tractor Semi-Trailer Using the Air Suspension System at all Axles of the Semi-Trailer

The air suspension system has become more and more popular in heavy vehicles and buses to improve ride comfort and road holding. This paper focuses on the evaluation of the dynamic load reduction at all axles of a semi-trailer with an air suspension system, in comparison with the one using a leaf spring suspension system on variable speed and road types. First, a full vertical dynamic model is proposed for a tractor semi-trailer (full model) with two types of suspension systems (leaf spring and air spring) for three axles at the semi-trailer, while the tractor’s axles use leaf spring suspension systems. The air suspension systems are built based on the GENSYS model; meanwhile, the remaining structural parameters are considered equally. The full model has been validated by experimental results, and closely follows the dynamical characteristics of the real tractor semi-trailer, with the percent error of the highest value being 6.23% and Pearson correlation coefficient being higher than 0.8, corresponding to different speeds. The survey results showed that the semi-trailer with the air suspension system can reduce the dynamic load of the entire field of speed from 20 to 100 km/h, given random road types from A to F according to the ISO 8608:2016 standard. The dynamic load coefficient (DLC) with the semi-trailer using the air spring suspension system can be reduced on average from 14.8% to 29.3%, in comparison with the semi-trailer using the leaf spring suspension system.

A feedback-feed-forward steering control strategy for improving lateral dynamics stability of an A-double vehicle at high speeds

A control strategy based on -type static output feedback combined with dynamic feed-forward is proposed to improve the high-speed lateral performance of an A-double combination vehicle(tractor–semitrailer–dolly–semitrailer) using active steering of the front axle of the dolly. Both feedback and feed-forward syntheses are performed via Linear Matrix Inequality (LMI) optimisation. From a practical point of view, the proposed controller is simple and easy to implement, despite its theoretical complexity. In fact, the measurement of the driver steering angle and only one articulation angle are required for the feed-forward and the feedback controllers, respectively. The results are verified using a high-fidelity vehicle model and confirm a significant reduction in yaw rate and lateral acceleration rearward amplification and also high-speed transient off-tracking, and subsequently improving the lateral stability and performance of the A-double combination vehicle during sudden lane change manoeuvres.

Setting up the 3D dynamic model to study the dynamic wheel load of the tractor semi-trailer

The paper presents how to build a 3D dynamic model to study the dynamic wheel load of the tractor semi-trailer. The method of structural separation of a multi body system (MBS) was used to build a 3D dynamic model, and the Newton-Euler equation was used to build the dynamic equation system of the tractor semi-trailer. The Matlab-simulink software was used to examine the dynamic wheel load of the tractor semi-trailer on 6 types of road. The results showed that, when braking the tractor semi-trailer at a speed of 60 km/h on 6 types of road with the grip coefficient of cpxmax = [0.5; 0.6; 0.7; 0.8; 0.9; 1.0], the wheel load of the front wheels Fz11 increases by about (70-80)%; the wheel load of the midle wheels Fz31 decreases by about (5-8)%; the wheel load of the rear wheels Fz61 decreases by about (13-20)%. When the tractor semi-trailer moves at a speed of 80 km/h, the wheel load of the front wheels Fz11 increases by about (72-82)%; the wheel load of the midle wheels Fz31 decreases by about (5-7)%; the wheel load of the rear wheels Fz61 decreases by about (14-20)%.

Improving roll stability of tractor semi-trailer vehicles by using H∞ active anti-roll bar control system

Tractor semi-trailers are increasingly playing an important role in freight transportation worldwide. Although most tractor semi-trailers are equipped with a passive anti-roll bar system, however accidents involving this type of vehicle are still frequent and have serious consequences. This paper presents an H∞ controller design for an active anti-roll bar system in order to enhance the roll stability of a tractor semi-trailer with the torque control generated at all axles. The considered performance outputs include the lateral acceleration, the normalised load transfer for both tractor and semi-trailer, as well as the magnitude of the torque control to avoid the actuator’s saturation. The effectiveness of the proposed method is evaluated in the frequency domain via the transfer function magnitude from the steering angle to the survey signals, and in the time domain through the nonlinear vehicle model of TruckSim® software. The evaluation results show that the roll stability of the tractor semi-trailer using the H∞ active anti-roll bar system has improved by more than 20% compared to a passive vehicle.

A new approach in modelling of hitch joint of a tractor semi-trailer using virtual Pacejka tyre model

In this study, a new approach in modelling of hitch joint of a tractor semi-trailer is proposed by adopting virtual Pacejka tyre model. The virtual Pacejka tyre model is connected with a 16 DOF tractor semi-trailer combinations in Matlab-Simulink software and verified using validated software known as TruckSim. Two sets of simulations are conducted in the verification process which involves a double lane change (DLC) and steep steer cornering (SSC) test. It is observed from the results that by modelling hitch joint as a virtual Pacejka tyre model, the behaviour of the developed model closely follows the behaviour of the validated TruckSim model.

Setting up the braking force measurement system of the tractor semi-trailer

The braking force of the tractor semi-trailer depends on many random factors and road parameters. Therefore, determining the braking force based on theoretical calculation or simulation is not accurate. This paper presents the method of setting up the braking force measurement system of the tractor semi-trailer on the road and constructing the braking dynamics model of the tractor semi-trailer to investigate the braking force using Matlab-Simulink software. The study results show that the average error between the simulation and experimental results of the tractor semi-trailer braking force is 9,81%.

ANALYSIS OF THROUGHPUT RATE OF HARVESTING AND TRANSPORTATION COMPLEX OF MACHINES FOR SUGAR BEET PRODUCTION

The article presents a methodology for analyzing the capacity of the harvesting and transport complex (HTC) for sugar beet, which is aimed at finding ways to rationally use the resource of machines in the technological complex. The reloading method of transportation of beet crop is considered, the feature of which is flexibility, adaptability to weather and climatic and economic conditions during harvesting. Under favorable weather conditions and the availability of a sufficient number of motor vehicles (MV), beets, which are taken from the combine harvester from the field by tractor semi-trailer (TS), are reloaded into heavy-duty MV, which are located on the road from the edge of the field, and transported to the sugar factory. In case of changes in conditions (in rainy weather, with overmoistened soil or with insufficient number of vehicles), a loader-cleaner is added to the complex of machines and the work of the complex switches to a transshipment or flow transshipment method. Harvesting and transportation of beets is considered as the work of the technological chain, which consists of three links: "field - beet harvester (BH)", "BH - NP", "NP - ATZ". The main steps of the throughput analysis are determination of the throughput of the first, second and third links, their comparison and subsequent selection and analysis of alternatives that allow to overcome the possible significant difference between their values. The possibility of reducing the throughput of the third link to the maximum possible - the throughput of the first link by reducing by a certain number of vehicles for the transportation of beets with a simultaneous increase in their technical speed. The given example of calculating the number of units of equipment in the harvesting and transport complex in accordance with the developed methodology proves its effectiveness and advantages. The analysis of the throughput capacity of the ZTC shows ways to improve the parameters of the transport process in the technological complex of harvesting and transport operations.

Instrumented load tests and layered elastic theory analysis of a large-scale EPS block embankment

This paper presents the behavioral results of a large-scale experimental EPS block embankment under different test and load conditions. The experimental embankment was designed and constructed to be similar to a road structure of flexible pavement and 22 kg/m3 EPS geofoam blocks supported by a soft soil subgrade. The experimental embankment was subjected to the Benkelman beam test and a load test using a 50,000 kg six-axle tractor semitrailer, and was instrumented with total pressure cells (TPC) to verify the vertical stresses propagated from the surface to the depth. Complementary analyses of both tests were performed by the layered elastic theory (LET). The results of the tests and analyses in the LET showed that using a correctly designed flexible pavement over the EPS blocks generates a structure with adequate performance. As well as in some previous studies, the elastic parameters determined in small samples of the EPS blocks tested in laboratory did not correspond to the behavior observed in field, where large blocks submitted to reduced deformations levels are employed. The conclusion was that LET can be used simply and conveniently as an adequate tool for pavement analysis with the presence of EPS blocks in its structure.

Using an LQR active anti-roll bar system to improve road safety of tractor semi-trailers

Introduction: Tractor semi-trailer vehicles are playing an increasingly important role in the global freight chain. However, due to the heavy total load and height of the center of gravity, this type of vehicle is often at a higher risk of instability than other vehicles. This paper focuses on improving the vehicle roll stability by using an active anti-roll bar system.
 Methods: The Linear Quadratic Regulator (LQR) approach is used for this purpose with the control signal being the torque generated by the active anti-roll bar system. In order to synthesize the controller, the roll angle of the vehicle body and the normalized load transfer at all axles of the tractor semi-trailer vehicle are considered as the optimal goals.
 Results: The simulation results in time and frequency domains clearly show the effectiveness of the proposed method for the active anti-roll bar system, because the reduction of the desired criterias is about 40% less when compared to a vehicle using the passive anti-roll bar system.
 Conclusions: The effectiveness of the active anti-roll bar system on improving the vehicle roll stability, has been verified in this theoretical study with the LQR optimal controller. This is an important basis for conducting more in-depth studies and future experiments.