Tractor-semitrailer Vehicle Research Articles

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

Offset backing path planning of tractor-semitrailer vehicles based on qualitative rules and geometric methods considering uncertainties

The backward behavior of tractor-semitrailer vehicles is particularly challenging compared to passenger vehicles, causing many difficulties not only for drivers but also for autonomous driving. Offset backing, which is one of the most important backward scenarios for articulated vehicles, can be applied to various path planning in a confined space, such as parking, and can be used for Advanced Driver Assistance Systems (ADAS) and autonomous driving. First of all, by analyzing the slow movement of a tractor-semitrailer vehicle in a confined space, standard unit motions and compound motions for general posture adjustment were defined. By approximating the offset backing driving paths of expert tractor-semitrailer drivers with a geometric method, qualitative path planning was completed by combining compound and unit motions. In addition, complementary motions were added to respond to errors that occur due to the simplicity of the qualitative path planning based on the geometric method. The usefulness of the developed offset backing path planning for tractor-semitrailer vehicles was demonstrated through repeated experimental tests with a model autonomous vehicle.

Time-optimal trajectory planning for autonomous parking of tractor-semitrailer vehicle based on piecewise Gauss pseudospectral method

For the autonomous parking problem of the tractor-semitrailer vehicle, a piecewise Gauss pseudospectral method is proposed as a trajectory planning scheme in this paper. Firstly, the trajectory planning problem is transformed into an optimal control problem by establishing a vehicle kinematics model for the low-velocity scene, the dynamic constraints including the physical constraints, the collision avoidance constraints, and the endpoint constraints. The optimal control problem are discretized into a nonlinear programming problem by piecewise Gauss pseudospectral method according to the movement area during parking process. The shortest time to complete parking is taken as the objective function. The Gauss pseudospectral method is further adopted to solve the nonlinear programming problem in the two parking stages. Three parallel parking conditions with different lengths of parking spaces and three vertical parking conditions with different widths of parking spaces are set for simulation verification based on Matlab/Simulink. The simulation results show that the proposed method can uniformly and effectively solve the trajectory planning problem of the tractor-semitrailer vehicle. Compared with the traditional pseudospectral method, a shorter parking time and a significantly higher convergence rate can be got with the method, which further indicates that the proposed method has good effectiveness and robustness.

An integrated longitudinal and lateral control strategy for low friction conditions of tractor semi-trailer vehicles

Driving articulated heavy vehicles (AHVs) at high-speeds is complicated due to their unstable motion modes. Accelerated motion trajectory planning is essential for collision avoidance (CA) maneuver in dynamic traffic conditions. This article proposes a new trajectory planning strategy for collision-free and feasible maneuver of a tractor semi-trailer truck in critical conditions in which the truck and the obstacles are moving with non-constant speeds. For this purpose, a convenient optimal practical trajectory for different tire-road frictional conditions, the physical limitation of the tires, and the stability status of the truck is suggested. The main strategy of the trajectory planning is to increase the capability of the control system using the longitudinal and lateral forces of the tires. A robust integrated controller is then proposed to control the longitudinal and lateral directions of the AHV of which the longitudinal controller is configured to track the longitudinal position considering the vehicle stability conditions, and the lateral controller is organized to follow the yaw rate, the lateral position of the tractor, and the articulation angle. The results show that the proposed novel strategy with integrated longitudinal and lateral control has convenient performance in high-speed and low friction conditions as well as normal situations.

Reaction Rod Link in Rear Cab Suspension to Control Cab Dynamics in Tractor-Semitrailer Vehicles

<div>Articulated vehicles form an important part of our society for the transport of goods. Compared to rigid trucks, tractor-trailer combinations can transport huge quantities of load without increasing the axle load. The fifth wheel (FW) acts as a bridge between the tractor and trailer, which can be moved within the range to achieve rated front and rear axle loads. When the FW is moved front, it adversely affects the cab dynamics and cab suspension forces. Compared to the cab pitch and roll, yaw motion increases drastically. The current study tries to address this issue by providing reaction rod links in the rear cab suspension.</div> <div>In this study, a 4×2 tractor with a three-axle semitrailer is considered by keeping the FW at its frontmost position, which is the worst-case scenario for a cab. Three different cases of reaction rod arrangement and its influence on cab dynamics are studied in comparison with a model without reaction rods. To assess this, time signal–based relative pseudo-fatigue damage, power spectral density (PSD), and level crossing plots are analyzed.</div> <div>The outcome shows that cab pitch, roll, and yaw motion reduce by a considerable amount with the presence of a reaction rod. Cab suspension forces will also reduce. The horizontal V-inclination of the reaction rod plays a major role in improving cab yaw motion and reducing the lateral forces. A straight link without any inclination helps in reducing the pitch and roll motion of the cab.</div>

Methods to introduce floating bridge motion and wind excitation on a model for the investigation of heavy vehicle dynamics

The proposed floating bridge solution at Bjørnafjorden in connection with the E39 infrastructure upgrade is an enabler to realize efficient transportation. This bridge and the vehicles shuttling on it will be exposed to inclement weather conditions. The waves and wind excite the floating bridge to induce compound motion in addition to the aerodynamic crosswinds directly interacting with the vehicles. Methods to introduce the complex motion of the floating bridge (multi-post test rig) and aerodynamic crosswinds on a tractor semi-trailer have been established and presented in this paper. The environment-vehicle-driver system is enabled through a co-simulation between MATLAB/Simulink (primary) and Adams (secondary). This complex interplay is studied on the intricate 627-DoF Adams vehicle model coupled with the Adams driver model. Numerical simulations are performed for multiple constant vehicle speeds under laden condition on a road with friction of 0.7 for the 1-year storm weather condition. Vehicle stability and safety assessments such as lane violation, path following ability, rollover risk, and lateral side slip limit are evaluated to draw inferences. Subsequently, permissible vehicle speed for a laden tractor semi-trailer to operate on the floating bridge is suggested. Furthermore, a simpler 9-DoF tractor semi-trailer vehicle model developed in MATLAB/Simulink combined with the pure pursuit tracking based driver model is compared with the Adams model under identical environmental conditions for an unladen case. The simpler vehicle-driver model is validated against the detailed Adams vehicle-driver model through numerical simulations for different constant vehicle speeds.

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.

Influence of Fifth Wheel Position on Cab Durability and Dynamics in Tractor-Semitrailer Vehicle

Influence of Fifth Wheel Position on Cab Durability and Dynamics in Tractor-Semitrailer Vehicle

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 effective nonlinear strategy for lateral stability increment of an articulated vehicle rigid cargo

In this paper, the effects of the most important parameters on directional dynamics of a tractor-semitrailer vehicle are examined. Initially, a three DOF dynamic model of a tractor-semitrailer vehicle is proposed. Then, the developed model is validated by means of TruckSim software during a standard maneuver. In order to analyze the system stability, the Lyapunov method has been used and the stability conditions have been extracted based on Routh criterion. The most important parameters are selected based on the articulation angle gain. Among the studied parameters, the semitrailer mass, the distance of the tractor unit center of mass and its front axle, and the tires cornering stiffness exhibited more effective behavior on the vehicle’s stability. The simulation results show that as the tractor center of mass moves toward its rear axle, the probability of the jackknifing increases. Moreover, an increment in the semitrailer mass leads to a turn of the semitrailer with respect to the tractor. Also, the understeer specification of the vehicle strengthens due to the tire cornering stiffness increment. Moreover, in order to increase the maneuverability of the articulated vehicle a new active steering controller is proposed using two different control methods. The controller is developed using the simplified dynamic model and the basis of feedback linearization method using dynamic sliding mode control method. In this system, the yaw rate and the lateral velocity of the tractor unit as well as articulation angle are studied as state variables which are targeted to track their desired references. Then, the vehicle dynamic performance is investigated during standard maneuvers. A more investigation shows that the track of the desired values of the vehicle state variables leads to eliminate off-tracking path.

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.

DETERMINATION OF PERFORMANCE INDICATORS OF THE TRUCK KrAZ-6510TE

In any economy there is a need for the bulky goods transportation which cannot be divided into smaller parts. Such cargoes include building structures, elements of industrial equipment, tracked or wheeled construction and agricultural machinery, heavy armored military vehicles. In any case, tractor-semitrailer should provide fast delivery of goods with minimal fuel consumption. In order to guarantee the goods delivery, tractor-semitrailers must be able to overcome the existing roads broken grade and be capable to tow a semi-trailer in off-road conditions. These properties are especially important for military equipment transportation. The important factor that determines a tractor-semitrailer mobility is its gradeability. The purpose of this work is to improve a tractor-semitrailer mobility with tractor units manufactured at PJSC “AutoKrAZ” by increasing the tractor-semitrailer gradeability. The customer requirements for a new tractor are determined by the maximizing the grade to 18°. The analysis of the characteristics of modern tractor-semitrailers for heavy haulage has shown that the highest rate of this grade is 16.7°. The factors determining the limiting gradeability value were analyzed, based on the tractor-semitrailer with a KrAZ-6510TE tractor and a semi-trailer with a full weight of 80 t. It has been developed a mathematical model to investigate the tractor and semi-trailer axles vertical reactions distribution on the tractor-semitrailer friction performances. The mathematical model has allowed to calculate the gradeability value that the tractor-semitrailer can overcome in case of wheels and road surface friction value and the tractive force magnitude from the engine. The mathematical model adequacy was confirmed by comparing the calculations results with the data of factory tests. The analysis showed that on a dry road the KrAZ-6510TE tractor with a 80 t gross weight semitrailer is capable to climb a gradient of 14,35 ° with its coupling mass full use condition. The engine's maximum torque allows the tractor-semitrailer to overcome a gradient of 10.45° It has been determined the ways to improve the design of the KrAZ-6510TE tractor to increase its gradeability. Keywords: tractor, tractor-semitrailer vehicle mobility, tractor-semitrailer vehicle gradeability.

Minimum Swept-Path Control for Autonomous Reversing of a Tractor Semi-Trailer

This paper presents a new approach for autonomous reversing of a tractor-semitrailer vehicle called minimum swept path control (MSPC). MSPC improves the performance of previous path following control (PFC) strategies, by minimizing the maximum excursion of the vehicle, while guaranteeing acceptable path following accuracy. A linear controller is devised, combining state feedback control with an optimized preview distance. A relationship between the maximum lateral offsets of the front axle of the tractor unit and the rear axle of the last trailer and the corresponding weights in the control cost function is established, and the controller is tuned to provide the best performance compromise. Several simulations of a tractor-semitrailer case are run, and the results show that the overall swept path width is reduced by more than 40% when compared with PFC methods.

Automatic steering control in tractor semi-trailer vehicles for low-speed maneuverability enhancement

In this paper, a controller for an automated steering articulated vehicle with the special capability to reduce off-tracking in low-speed maneuvers is proposed. Conventional tractor–trailers have a large off-tracking in low-speed maneuvers. In the proposed vehicle, all wheels of the tractor and trailer are steerable (all wheel steering). The controllers of the tractor and trailer work independently, and each one consists of two layers. A fuzzy controller and a PID controller are designed in the upper and lower layer, respectively, to control the actuators. The aim of the controller is to ensure that the end points of both the tractor and the trailer exactly follow the path of tractor’s first point. To assess the performance of proposed controller as well as steerability effect of all wheels in low speeds, the TruckSim simulation software is used. The simulation results confirm that the proposed approach improves the maneuverability and accuracy of path tracking not only compared to conventional vehicles but also to the conventional tractor–active trailer scheme, which was previously proposed by a number of studies. Additionally, it reduces lateral tire forces to enhance the working life.

Nonlinear analysis of a closed-loop tractor-semitrailer vehicle system with time delay

In this paper, a nonlinear analysis is performed on a closed-loop system of articulated heavy vehicles with driver steering control. The nonlinearity arises from the nonlinear cubic tire force model. An integration method is employed to derive an analytical periodic solution of the system in the neighbourhood of the critical speed. The results show that excellent accuracy can be achieved for the calculation of periodic solutions arising from Hopf bifurcation of the vehicle motion. A criterion is obtained for detecting the Bautin bifurcation which separates branches of supercritical and subcritical Hopf bifurcations. The integration method is compared to the incremental harmonic balance method in both supercritical and subcritical scenarios.

Fuzzy Logic Based Control of the Lateral Stability of Tractor Semitrailer Vehicle

A novel control scheme is proposed to improve the yaw stability of a tractor semitrailer vehicle in critical situations. The control scheme is a two-layer structure consisting of an upper yaw moment controller and a lower brake force distributor. The tractor and the trailer are, respectively, stabilized by two independent fuzzy logic based yaw moment controllers. The controllers for the tractor and the trailer are, respectively, designed to track the reference yaw rate of the tractor and the hitch angle between the tractor and the trailer while considering the variation of the hitch angular rate at the same time. The corrective yaw moments determined by the corresponding upper fuzzy yaw moment controllers are realized by active wheel braking. The performance of the proposed control scheme is evaluated by simulations on a nonlinear vehicle model. The results demonstrate that the proposed control scheme is robust and effective in stabilizing the severe instabilities such as jackknife and trailer oscillation in the chosen simulation scenarios. It is believed that this control scheme is robust to the variation of road adhesion conditions.

Analysis of bifurcation and stability for a tractor semi-trailer in planar motion

This paper is intended for bifurcation analysis of a nonlinear tractor semi-trailer vehicle model in planar motion and for investigating its stability under constant running conditions. Bifurcation analysis shows that bifurcation diagrams of a tractor semi-trailer are quite different from those of a single-unit vehicle. Some instability phenomena of the vehicle system such as jackknifing, sideslip, and spinning are explained by correlating them with the behaviour in the neighbourhood of unstable fixed points based on analysis of eigenvectors, phase trajectories, and status of lateral tyre force saturation. It is also found that yaw planar instability of a tractor semi-trailer is caused by lateral tyre force saturation of the tractor's rear axles and/or the trailer's axles. Moreover, the stability region in the state space is demarcated, and a stability index for evaluating size of the stability region in a feasible domain is proposed. Yaw stability under constant driving conditions is analysed by using the proposed stability index.

Effect of parameters on roll dynamic response of an articulated vehicle carrying liquids

Directional response and roll stability characteristics of a partly filled tractor semi-trailer vehicle, with cylindrical tank, 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 filled volume, kinematic viscosity of liquid cargo 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-offreedom of a tractor semi-trailer tank model. The dynamic fluid slosh within the tank is modeled using three-dimensional Navier-Stokes equations, coupled with the volume-of-fluid equations and analyzed using FLUENT software. The coupled tank-vehicle model is subsequently analyzed to determine the roll stability characteristics for different conditions and maneuvers. The results show effects of parameter variations on roll stability of the vehicle carrying liquid and also fluid’s behavior in interaction with a vehicle’s dynamics.

Effect of tank shape on roll dynamic response of an articulated vehicle carrying liquids

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.

Tractor-Semitrailer Vehicle Stability Control Based on TruckSim-Simulink Co-Simulation

AbstractA nonlinear tractor-semitrailer vehicle simulation model is established based on TruckSim used to validate the proposed control scheme. The yaw dynamics of the entire vehicle is stabilized by applying differential braking to the wheels of the tractor and the trailer. The control system, which was designed in Matlab/Simulink, is a two-level structure with the upper yaw moment controller outputting an additional yaw moment and the lower control allocator realizing the additional yaw moment by appropriately coordinating the wheel brake actions of the tractor and the trailer. A Trucksim-Simulink co-simulation model is constructed, and based on which the proposed control scheme is validated by a single-lane change maneuver on a slippery road. Simulation results reveal that designing and evaluating vehicle stability control strategies with the TruckSim-Simulink co-simulation method is effective. The proposed control scheme can significantly improve the vehicle yaw stability and roll stability.