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Insects use dynamic articulation and actuation of their abdomen and other appendages to augment aerodynamic flight control. These dynamic phenomena in flight serve many purposes, including maintaining balance, enhancing stability, and extending maneuverability. The behaviors have been observed and measured by biologists but have not been well modeled in a flight dynamics framework. Biological appendages are generally comparatively large, actuated in rotation, and serve multiple biological functions. Technological moving masses for flight control have tended to be compact, translational, internally mounted and dedicated to the task. Many flight characteristics of biological flyers far exceed any technological flyers on the same scale. Mathematical tools that support modern control techniques to explore and manage these actuator functions may unlock new opportunities to achieve agility. The compact tensor model of multibody aircraft flight dynamics developed here allows unified dynamic and aerodynamic simulation and control of bioinspired aircraft with wings and any number of idealized appendage masses. The demonstrated aircraft model was a dragonfly-like fixed-wing aircraft. The control effect of the moving abdomen was comparable to the control surfaces, with lateral abdominal motion substituting for an aerodynamic rudder to achieve coordinated turns. Vertical fuselage motion achieved the same effect as an elevator, and included potentially useful transient torque reactions both up and down. The best performance was achieved when both moving masses and control surfaces were employed in the control solution. An aircraft with fuselage actuation combined with conventional control surfaces could be managed with a modern optimal controller designed using the multibody flight dynamics model presented here. [ABSTRACT FROM AUTHOR]

This article shows the main transformations in the production processes of Superpolo S.A.S and its brand Marcopolo, for the development of new articulated and bi-articulated buses with concept BRT (Bus Rapid Transit), which allow a reduction of emission to the environment, and with the quality levels according to the new tender processes in Colombia and particularly for mass transport system in Bogotá (Transmilenio). The article describes the automotive market in Colombia, its more relevant bus bodybuilder assemblers, and its challenges, focused on the importance of generating initiatives that mitigate the gaps and how Superpolo addressed them. Additionally, a review of the improvements implemented, such as the Andon, the fiberglass lamination train process, metal parts bending, dry and paint ovens, new manufacture cells, till and leak tests. These improvements made it possible to increase the installed capacity to comply with delivery times, in addition to positive results in the ergonomics of the workers, thus a national company was able to provide new solutions to face the demand for buses for the BRT systems of Colombia and with projection for the region. [ABSTRACT FROM AUTHOR]

Vehicle aerodynamics and dynamics in gusty crosswind conditions are of increasing significance for the lateral stability of heavy ground vehicles, especially articulated heavy vehicles (AHVs). The unsteady aerodynamic loads acting on AHVs can greatly exceed loads of a single-vehicle unit; these may deteriorate the lateral stability and lead to a loss of handling control. In this study, the time characteristics of aerodynamic loads and dynamic response of a tractor semi-trailer were considered, based on simulating the relative motions of these two components to reproduce actual scenarios of AHVs in crosswinds. A dynamic fully coupled method was developed and adopted to realize a real-time data exchange of flow fields and multi-bodies. Two multi-body systems (for non-articulated heavy vehicles and AHVs, respectively) were created to study the influences of the relative motions on the aerodynamic performance and lateral stability of the vehicles. The Reynolds-averaged Navier–Stokes (RANS) method and renormalization group (RNG) k − ε equation were adopted to account for the turbulence. A wind tunnel experiment was conducted to validate the numerical method. The results show that AHVs are more sensitive to the crosswind, with significant differences in the magnitudes and directions of the aerodynamic forces, moments, dynamic yaw angle, and lateral displacement. Three different wind types were considered (step, linear, and sinusoidal). The step crosswind produces the largest average lateral force and yawing moment, resulting in the largest lateral displacement and yaw angle. The largest hitch angle is found for linear gusts, presenting the highest safety risks in regard to jackknifing and trailer swings. [ABSTRACT FROM AUTHOR]

Lateral stability is quite essential for the vehicle. For the vehicle with an articulated steering system, the vehicle load and steering system performance is quite different from the passenger car with the Ackman steering system. To investigate the influence of the tire characteristics and vehicle parameters on lateral stability, a single-track dynamic model is established based on the vehicle dynamic theory. The accuracy of the built model is validated by the field test result. The investigated parameters include the tire cornering stiffness, vehicle load, wheelbase, and speed. Based on the snaking steering maneuver, the lateral stability criteria including the yaw rate, vehicle sideslip angle, tire sideslip angle, and lateral force are calculated and compared. The sensitivity analysis of the tire and vehicle parameters on the lateral stability indicators is initiated. The results demonstrated that the parameters that affect the lateral vehicle stability the most are the load on the rear part and the tire cornering stiffness. The findings also lay a foundation for the optimization of the vehicle's lateral stability. [ABSTRACT FROM AUTHOR]

Due to the declining birthrate and aging population, the shortage of labor in the construction industry has become a serious problem, and increasing attention has been paid to automation of construction equipment. We focus on the automatic operation of articulated six-wheel dump trucks at construction sites. For the automatic operation of the dump trucks, it is important to estimate the position and the articulated angle of the dump trucks with high accuracy. In this study, we propose a method for estimating the state of a dump truck by using four global navigation satellite systems (GNSSs) installed on an articulated dump truck and a graph optimization method that utilizes the redundancy of multiple GNSSs. By adding real-time kinematic (RTK)-GNSS constraints and geometric constraints between the four antennas, the proposed method can robustly estimate the position and articulation angle even in environments where GNSS satellites are partially blocked. As a result of evaluating the accuracy of the proposed method through field tests, it was confirmed that the articulated angle could be estimated with an accuracy of 0.1 ∘ in an open-sky environment and 0.7 ∘ in a mountainous area simulating an elevation angle of 45 ∘ where GNSS satellites are blocked. [ABSTRACT FROM AUTHOR]

This paper presents nonlinear mathematical models of one- and two-track multitrailer vehicles. We derive nonlinear equations of motion in the form of a system of implicit ordinary differential equations (ODEs) by using Lagrangian mechanics. The system of ODEs has the minimum number of states and equations that enables efficient computations yet maintains the most important nonlinear vehicle dynamic behavior and allows actuator coordination and energy consumption evaluation. As examples, we build different models of a 4-unit long combination vehicle, i.e., two-track 11-axle and single-track 6-axle nonlinear models as well as a linear single-track 6-axle model. We compare the performance of these models to experimental data of different driving maneuvers. The nonlinear single-track model demonstrates close dynamic behavior to the experiment, which makes it an efficient alternative to the two-track model. The vehicle equations can be generated automatically by using the code provided in this paper and subsequently used for conducting frequency analysis, evaluating energy consumption, deriving performance measures from simulations, and facilitating optimal control applications that involve combined steering, braking and propulsion control.

In recent years, control design for unmanned systems, especially a tractor–trailer system, has gained popularity among researchers. The emergence of such interest is caused by the potential reduction in cost and shortage of number of workers and labors. Two industries will benefit from the advancements of these types of systems: agriculture and cargo. By using the unmanned tractor–trailer system, harvesting and cultivating plants will become a safe and easy task. It will also cause a reduction in cost which in turn reduces the price on the end consumers. On the other hand, by using the unmanned tractor–trailer system in the cargo industry, shipping cost and time for the item delivery will be reduced. The work presented in this paper focuses on the development of a path tracking and a cascaded controller to control a tractor–trailer in reverse motion. The path tracking controller utilizes the Frenet–Serret frame to control the kinematics of the tractor–trailer system on a desired path, while the cascade controller's main objective is to stabilize the system and to perform commands issued by the path tracker. The controlled parameters in this proposed design are the lateral distance to a path, trailer's heading angel, articulated angel, and articulated angle's rate. The main goal of such controller is to follow a path while the tractor–trailer system is moving in reverse and controlling the stability of the articulated vehicle to prevent the occurrence of a jackknife incident (uncontrolled state). The proposed controller has been tested in a different scenario where a successful implementation has been shown. [ABSTRACT FROM AUTHOR]

When designing articulated tractor-trailer systems, engineers should take care to contrast some undesired phenomena associated with the lateral dynamics: the path off-tracking, namely the trajectory deviation of the points of the two units compared to the midpoint of the tractor fore; the rearward amplification of the transverse acceleration. The off-tracking may lead the vehicle tail to invade the opposite direction lane or the emergency lane, whereas the rearward amplification may involve the danger of the trailer rollover. Nonetheless, the arrangement of multi-steering axle systems with the proper correlation among the steering angles may substantially cancel the off-tracking, both along a path with constant curvature and while entering or leaving the road bend. Moreover, the proper control of the increase and decrease of the steering angle during the transient phases can restrain the lateral acceleration of the towed unit. The present analysis considers several nonlinear effects of the vehicle lateral dynamics, such as large steering angles, nonlinear cornering characteristics and changes of the cornering forces because of the centrifugal effect. The goal is a practical formulation of the correlation among the steering angles to correct the vehicle run and ensure lateral stability. [ABSTRACT FROM AUTHOR]

Automatic guidance systems and autonomous vehicles require tested methods of path generation to ensure successful maneuvers (such as automatic trajectory correction and headland turn management). In this study, an evolution of Zakin’s kinematic modeling, as applied in the automobile industry, is proposed for an agricultural poly-articulated vehicle (representing a tractor or other type of towing vehicle with one or more towed implements attached with an articulated hitch). Geometry, vehicle ground speed, and angular steering velocity are considered in the generation of maneuvering paths. Based on the specifics of real field conditions (slope, plant residue, resistance due to soil compaction, etc.), the initial model was improved by introducing correction coefficients. An experimental setup is proposed using a tractor with two towed implements and a testing method involving point-to-point path comparison. The modeling method has potential for integrating more complex procedures (such as path generation, geolocation, and following) into the design of a maneuvering management system for agricultural machines, which can contribute to the efficiency of field operations. [ABSTRACT FROM AUTHOR]

Professional truck drivers frequently face the challenging task of manually backwards manoeuvring articulated vehicles towards the loading bay. Logistics companies experience costs due to damage caused by vehicles performing this manoeuvre. However, driver assistance aimed to support drivers in this special scenario has not yet been clearly established. Additionally, to optimally improve the driving experience and the performance of the assisted drivers, the driver assistance must be able to continuously adapt to the needs and preferences of each driver. This paper presents the VISTA-Sim, a platform that uses a virtual reality (VR) simulator to develop and evaluate personalized driver assistance. This paper provides a comprehensive account of the VISTA-Sim, describing its development and main functionalities. The paper reports the usage of VISTA-Sim through the scenario of parking a semi-trailer truck in a loading bay, demonstrating how to learn from driver behaviours. Promising preliminary results indicate that this platform provides means to automatically learn from a driver's performance. The evolution of this platform can offer ideal conditions for the development of ADAS systems that can automatically and continuously learn from and adapt to an individual driver. Therefore, future ADAS systems can be better accepted and trusted by drivers. Finally, this paper discusses the future directions concerning the improvement of the platform. [ABSTRACT FROM AUTHOR]

In this paper, the seven degrees of freedom (DOF) nonlinear system model of articulated vehicles, including the vehicle dynamics model, tire and hydraulic steering system model, and the linearized ideal reference model, is constructed. A layered stability controller for the articulated vehicle is built. The particle swarm optimization (PSO)-based variable parameter linear quadratic regulator (LQR) for the upper-level yaw torque controller and the lower-level torque distributor based on the principle of the minimum tire utilization are established. The effectiveness of the LQR upper-level yaw torque controller for an articulated vehicle at different speeds and control references are compared and analyzed through feedforward and feedback control. We optimize the parameters in the LQR controller using PSO and verify the improvement in the controller’s performance with optimized parameters. Overall, the effect of front and rear-integrated control is best, followed by rear-based and front-based control. The PSO algorithm to optimize the LQR controller parameters for snaking oscillation control is effective.

Articulation angle sensing is an essential component of manoeuvrability and stability control systems for articulated heavy goods vehicles, particularly long combination vehicles. Existing solutions to this sensing task are limited by reliance on trailer modifications or information or by measurement accuracy, or both, restricting commercial adoption. In this paper we present a purely tractor-based sensor concept comprising a rear-facing camera and the parallel tracking and mapping (PTAM) image processing algorithm. The system requires no prior knowledge of or modifications to the trailer, is compatible with planar and non-planar trailer shapes, and with multiply-articulated vehicle combinations. The system is validated in full-scale vehicle tests on both a tractor semi-trailer combination and a truck and full-trailer combination, demonstrating robust performance in a number of conditions, including trailers with non-planar geometry and with minimal visual features. Average RMS measurement errors of 1.19, 1.03 and 1.53 degrees were demonstrated for the semi-trailer and full-trailer (drawbar and semi-trailer) respectively. This compares favourably with the state-of-the-art in the published literature. A number of improvements are proposed for future development based on the observations in this research. [ABSTRACT FROM AUTHOR]

Unmanned pavement construction is of great significance in China, and one of the most important issues is how to follow the designed path near the boundary of the pavement construction area to avoid curbs or railings. In this paper, we raise a simple yet effective controller, named the proportional-integral-radius and improved particle swarm optimization (PIR-IPSO) controller, for fast non-overshooting path-following control of an unmanned articulated vehicle (UAV). Firstly, UAV kinematics model is introduced and segmented UAV steering dynamics model is built through field experiments; then, the raw data collected by differential global positioning system (DGPS) is used to build the measurement error distribution model that simulates positioning errors. Next, line of sight (LOS) guidance law is introduced and the LOS initial parameter is assigned based on human driving behavior. Besides, the initial control parameters tuned by the Ziegler-Nichols (ZN) method are used as the initial iterative parameters of the PSO controller. An improved PSO fitness function is also designed to achieve fast non-overshoot control performance. Experiments show that compared with the PSO, ZN and ZN-PSO controller, the PIR-PSO-based controller has significantly less settling time and almost no overshoot in various UAV initial states. Furthermore, compared with other controllers, the proposed PIR-IPSO-based controller achieves precise non-overshoot control, relatively less settling time and centimeter-level positioning error in various initial deviations. [ABSTRACT FROM AUTHOR]

This research is concerned with the use of double walls filled with foam aluminum for an open wagon to decrease loading during operational modes. The research presents the strength calculation for the frame of a wagon with a consideration of the engineering solutions proposed. It was found that the maximum equivalent stresses appeared in the bottom section of the center sill behind the back support; they amounted to about 290 MPa and did not exceed the allowable values. The maximum displacements were in the middle parts of the main longitudinal beams of a section, and they amounted to 8.8 mm. The research also presents the strength calculation for a weld joint in the maximum loaded zones of the frame of a wagon and reports the results of the modal analysis of the frame of the improved wagon. It was found that the oscillation frequencies did not exceed the allowable values. The results of the research may be useful for those who are concerned about designing innovative rolling stock units and improving the operational efficiency of railway transport. [ABSTRACT FROM AUTHOR]

In this research we present an algorithm for a six-wheeled robotic vehicle with articulated suspension (RVAS) to estimate the vehicle velocity and acceleration states, slip ratio and the tire forces. The estimation algorithm consists of six parts. In the first part, a wheel state estimator estimates the wheel rotational speed and its angular acceleration using Kalman filter, which is used to estimate the longitudinal tire force distribution in the second part. The third part is to estimate respective longitudinal, lateral, and vertical speeds of the vehicle and wheels. Based on these speeds, the slip ratio and slip angle are estimated in the fourth part. In the fifth part, the vertical tire force is then estimated. In the sixth part, the lateral tire force is then estimated. For a simulation test environment, the RVAS dynamic model is developed using Matlab and Simulink. The estimation algorithm is then verified in simulation using the vehicle test data and different test scenarios. It is found from simulation results that the proposed estimation algorithm can estimate the vehicle states, longitudinal tire forces efficiently. Moreover, a small prototype of the robotic vehicle is fabricated for experimental verification of the estimation algorithm. Various experiments are executed in pavement and off-road driving to estimate the wheel angular position, velocity and acceleration states and finally the slip ratio is estimated in these situations. [ABSTRACT FROM AUTHOR]

This paper investigates the active steering control of the tractor and the trailer for the articulated heavy vehicle (AHV) to improve its high-speed lateral stability and low-speed path following. The four-degree-of-freedom (4-DOF) single track dynamic model of the AHV with a front-wheel steered trailer is established. Considering that the road information at the driver's focus is the most clear and those away from the focus blurred, a new kind controller based on the fractional calculus, i.e., a focus preview controller is designed to provide the steering input for the tractor to make it travel along the desired path. In addition, the active steering controllers based on the linear quadratic regulator (LQR) and single-point preview controller respectively are also proposed for the trailer. However, the latter is designed on the basis of the articulation angle between the tractor and trailer, inspired by the idea of the driver's single-point preview controller. Finally, the single lane change maneuver and 90o turn maneuver are carried out. And the simulation results show that compared with the single-point preview controller, the new kind preview controller for the tractor can have good high speed maneuvering stability and low speed path tracking ability by adjusting the fractional order of the controller. On this basis, three different AHVs with the same tractor are simulated and the simulation results show that the AHV whose trailer adopts the single-point preview controller has better high-speed lateral stability and low-speed path tracking than the AHV whose trailer adopts the LQR controller. [ABSTRACT FROM AUTHOR]

The paper deals with linkages used to actuate the retractable top of convertible passenger car, which are either a simple articulated 4-bar mechanism or a stacking multi-contour n-bar mechanism. The car top that can fold or unfold is consisting of two or three hard components. The folding linkage of the hard top is a planar kinematic chain with articulated bars which allows the two or three top parts to be stacked into the trunk room. To be observed that the first hard component of the kinematic chain is the car rear screen and the second hard part is actually the retractable top. In order to fold the car top and the rear screen, the door trunk is actuated by means of a simple hinge pair or a 4-bar mechanism. In the case of a larger passenger car, the top consists of two parts and together with the rear screen form the open kinematic chain which can be closed by means of some stacked kinematic chains. Using CAD modeling and kinematic simulation of the retractable textile car top linkage used on convertibles, the mechanism efficiency regarding its operation can be improved. Through Inventor® software the user can modify any part or subassembly of the mechanism at any moment. This can be done by means of the parametric design which allows that any changing on a component to be instantaneous reflected on the assembly which that part belongs to. [ABSTRACT FROM AUTHOR]

This study constructs a nonlinear dynamic model of articulated vehicles and a model of hydraulic steering system. The equations of state required for nonlinear vehicle dynamics models, stability analysis models, and corresponding eigenvalue analysis are obtained by constructing Newtonian mechanical equilibrium equations. The objective and subjective causes of the snake oscillation and relevant indicators for evaluating snake instability are analysed using several vehicle state parameters. The influencing factors of vehicle stability and specific action mechanism of the corresponding factors are analysed by combining the eigenvalue method with multiple vehicle state parameters. The centre of mass position and hydraulic system have a more substantial influence on the stability of vehicles than the other parameters. Vehicles can be in a complex state of snaking and deviating. Different eigenvalues have varying effects on different forms of instability. The critical velocity of the linear stability analysis model obtained through the eigenvalue method is relatively lower than the critical velocity of the nonlinear model. [ABSTRACT FROM AUTHOR]

Articulated tracked vehicles (ATVs) exhibit enhanced steerability but reduced yaw stability. Apart from the track-terrain contact, the dynamics of the articulated frame steering (AFS) system strongly influences the stability of ATVs. We developed a detailed hydraulic steering system and a yaw-plane ATVs model for vehicle stability research. The transient characteristic of track-ground contact was considered. The multibody dynamics model by Recurdyn/Track software was compared with the established model to verify the model correctness at time-domain and frequency-domain. The result suggests that the vehicle yaw stability can be evaluated in terms of the oscillation frequency, damping ratio, overshoot, and steady-state deviation of articulation angle response. A multi-objective optimization is proposed to obtain the optimized structural parameters of AFS system by employing response surface method (RSM) and non-dominated sorting genetic algorithm II (NSGA-II). The optimal solutions revealed that more compact mechanism design of AFS system contributes to a compromise stability performance with 4.44 % decrease in the oscillation frequency and 10.3 % decrease in the damping ratio. [ABSTRACT FROM AUTHOR]

Semi-trailer articulated vehicles are mainly used for transportation of goods and industrial products. The vehicles are made of two or more vehicular units that are coupled by a mechanical device called, hitch point. The static and dynamic behavior of these vehicles differs from those of other vehicles, while accidents on these vehicles are fatal and disastrous. Therefore, there is need to know more about the static and dynamic characteristic of these vehicle, in order to ensure safety of lives and properties. This paper provides literature review on the aforementioned vehicle in order to have more insight on how to improve its stability. It was observed from the literatures review that, the higher the weight on this vehicle, the farther the distance of centre of gravity (CG) from the hitch point. This affects the safety margin against rollover stability of these vehicles. The fifth wheel lead, and the distance between the tractor, and the trailer CG were also found to play a vital role in influencing the stability of these vehicles. However, it was observed that, it would of great important for a tractor unit with one rear axle, to have the fifth wheel lead, to be as large as possible in order to control the vehicle instability. Therefore, due to the unusual behavior of these vehicles, more research works are needed in order to have more insight on the static and dynamic characteristic of these vehicles as to improve the safety of lives and properties. [ABSTRACT FROM AUTHOR]

The fundamentals of mechanical system dynamics were established before the beginning of the industrial era. The development of computers in the 20th century revolutionized mechanical system dynamics owing to the development of numerical simulation. This Special Issue aims at disseminating the latest research findings, and ideas in the field of mechanical systems dynamics, with particular emphasis on novel trends and applications. Conclusions This Special Issue contains twenty interesting research papers focused on advances in mechanical systems dynamics, covering a wide area of applications. [Extracted from the article]

With the development of global urbanization and the construction of regional urbanization, residents around urban cities are increasingly making demands on urban public transportation system. A new kind of modern public transportation vehicle named Multi-Articulated Guided Vehicle based on Virtual Track (MAAV-VT) with the advantages of beautiful, smart energy conservation and environmental protection is proposed in this paper, which aims at optimizing the public transportation system between and within urban areas. Therefore, concentrating on the general design and control strategy, the main contents of this paper are as follows. At first, the design concepts and key technologies of MAAV-VT are introduced. It is the fusion of urban rail transit operation mode and advanced automotive technologies, which have the characteristics of 100% low-floor, medium to high velocity, medium to big capacity, and low construction cost. Then, as the core subsystem, to guarantee the properties of self-guiding and trajectory tracking of the new vehicle, this paper is focused on the control system based on the dynamics and kinematics model of the whole multi-articulated vehicle. The multi-trace-points cooperative trajectory tracking control strategy on the basis of the circulation of feasible path generation method is proposed and the lateral controller is designed for trajectory tracking. The process of feasible path generation is conducted once the tracking error exceeded. A simulation platform is built considering the mechanical properties of each vehicle element and the characteristic of articulated mechanism. Finally, the function of control system is validated. The tracking error of each vehicle elements would be reduced to make sure the whole multi-articulated vehicle moves along the preset virtual track. [ABSTRACT FROM AUTHOR]

This article develops a four-level test system for accurately evaluating pavement compaction performance of autonomous articulated vehicles. In the evaluation layer, various performance indicators are evaluated, including the stability, rapidity and accuracy of trajectory tracking, and the ratio of required compaction to actual compaction once and twice and compaction repeatability index when pavement compaction. The guidance and control layer can be described in terms of theory and application. At the theoretical level, the line of sight guidance algorithm and incremental proportional integral control algorithm are introduced to eliminate system control lag. Among them, the best line of sight guidance and incremental proportional integral control parameters are selected by the Elitist strategies genetic algorithm, and the initial parameters are set according to human driving experience initial control parameters. At the application level, the BECKHOFF controller, a kind of programmable logic controller, acts as the main guidance and control unit in the four-level control system, fixed speed is given to the autonomous articulated vehicle by setting the engine speed and transmission gear, and steering wheel angle is adjusted in real time by the BECKHOFF controller. In the sensor level, a simplified sensor configuration is used to reduce overall cost. The comparative simulation results of no controller, the incremental proportional integral controller, line of sight guidance-incremental proportional integral controller with human driving experience initial control parameters, line of sight guidance-incremental proportional integral controller with random initial control parameters, and elitist strategies genetic algorithm-line of sight guidance-incremental proportional integral controller with human driving experience initial control parameters manifest evidently that the proposed elitist strategies genetic algorithm-line of sight guidance-incremental proportional integral controller with human driving experience initial control parameters has almost no steady-state error, no overshoot, and short settling time. Field results show that ratio of required compaction to actual compaction once achieves 100%, ratio of required compaction to actual compaction twice achieves 94.6%, and compaction repeatability index achieves 35%. [ABSTRACT FROM AUTHOR]

The present study discusses the effects of stability control for multi-articulated vehicles on the lane-keeping performance. Vector follower control (VFC) compensates the direction difference angles between the velocity vector at the front articulation point and the trailer using active steering of the trailer wheels. The control effects are evaluated by examining computer simulation with the driver-vehicle system, which consists of a multi-articulated vehicle model, a driver model, and VFC. VFC prevents amplification of the lateral displacements of rearward trailers, whereas the lane-keeping performance of a vehicle without VFC deteriorates. VFC does not, however, contribute to the performance of the tractor or the steering operation of the driver. A lane-keeping-assistance (LKA) system using direct yaw-moment control is applied to the tractor. The LKA system suppresses the lateral deviation of the tractor and the steering effort of the driver. In addition, the combination of VFC and the LKA system makes it possible to reduce the lateral deviations of all of the vehicles, as well as the steering effort of the driver. [ABSTRACT FROM AUTHOR]

Recent trends in vehicle engineering prove the great effort that scientists and industries have made in seeking solutions to enhance both the performance and the safety of vehicular systems. Physical models concerning vehicle-ground interaction, control strategies for the vehicle and its subsystems, and new technologies are developing all over the world for this purpose. The accepted scientific contributions covered topics concerning new results and studies in the following areas related to the interaction of vehicle dynamics and the ground: Physical models concerning tire-road and vehicle-ground interaction: In particular, [[1]] refers to new developments in airless (or non-pneumatic) tires, representing a significant perspective in the future evolution of such components. [Extracted from the article]

Due to the unique steering mechanism and driving characteristics of the articulated vehicle, a hybrid path planning method based on the articulated vehicle model is proposed to meet the demand of obstacle avoidance and searching the path back and forth of the articulated vehicle. First, Support Vector Machine (SVM) theory is used to obtain the two-dimensional optimal zero potential curve and the maximum margin, and then, several key points are selected from the optimal zero potential curves by using Longest Accessible Path (LAP) method. Next, the Cubic Bezier (CB) curve is adopted to connect the curve that satisfies the curvature constraint of the articulated vehicle between every two key points. Finally, Back and Forth Rapidly-exploring Random Tree with Course Correction (BFRRT-CC) is designed to connect paths that do not meet articulated vehicle curvature requirements. Simulation results show that the proposed hybrid path planning method can search a feasible path with a 90-degree turn, which meets the demand for obstacle avoidance and articulated vehicle back-and-forth movement. [ABSTRACT FROM AUTHOR]

Featured Application: The research results will inspire technicians to design modern railway vehicles with higher operational efficiency. This article deals with the dynamic load and strength of the carrying structures of articulated circular-tube wagons. The study was conducted on the carrying structures of wagons equipped with new draft gear concepts. The accelerations on the carrying structures of wagons were determined using mathematical modeling. The results of modeling show that implementation of the draft gear concept can decrease the dynamic load of wagons by about 10% in comparison with that of a typical SA-3 coupler. Using the created computational models, the service life of the structure of the proposed articulated wagons was also determined. This research will encourage engineers to design modern structures of railway vehicles of higher operational efficiency. [ABSTRACT FROM AUTHOR]

This paper proposes a novel path-following control algorithm for articulated steer vehicles (ASV) by dynamic virtual terrain field (VTF) method. The altitude function of VTF, with robustness in fitting different working conditions, is adapted for the derivation of target steering wheel angle. Prior to the development of the controller, the nonlinear ASV model coupling with a full-hydraulic steering system is verified by real test and Adams/View software simulation. To get a precise path-following result, the sideslip angle is considered and controlled by 'direct sideslip control' and 'road roll control'. The function of VTF is established and divided into primary and dynamic terrain field reference to the parameter variabilities. According to the vehicle dynamics model and the tire forces generated from the vehicle inclination on virtual terrain, the target articulation angle composed of the main angle and compensatory angle is derived. Simulations of path-following control at different road conditions, together with other types of controllers, are conducted and compared to show the feasibility and effectiveness of the proposed path-following control algorithm. [ABSTRACT FROM AUTHOR]

This article describes a hybrid simulation approach meant to facilitate the realization of a simulator for underwater vehicles with one or more manipulators capable of simulating the interaction of the vehicle with objects and structures of the environment. The hybrid simulation approach is first described and motivated analytically, then an analysis of simulation accuracy is proposed, where, in particular, the implications of added mass simulation are discussed. Then, a possible implementation of the proposed architecture is shown, where a robotic simulator of articulated bodies, capable of stable and accurate simulation of contact forces, although unfit to simulate any serious hydrodynamic model, is tightly interfaced with a general purpose dynamic systems simulator that is used to simulate the hydrodynamic forces, the vehicle guidance, navigation, and control system, and also a man–machine interface. Software details and the technicalities needed to interface the two simulators are also briefly presented. Finally, the results of the simulation of three operational scenarios are proposed as qualitative assessment of the simulator capabilities. [ABSTRACT FROM AUTHOR]

Heavy-wheeled vehicles with articulated hydraulic steering systems are widely used in construction, road building, forestry, and agriculture, as transport units and tool-carriers because they have many unique advantages that are not available in car steering systems, based on the Ackermann principle, such as—high cross-country mobility, excellent maneuverability, and high payload and lift capacity, due to heavy axles components. One problem that limits their speed of operation and use efficiency is that they have poor directional stability. During straight movement, articulated tractors' deviate from a straight line and permanent driver correction is required. This limits the vehicles' speed and productivity. In this study, we describe a driver-aid system concept that would improve the directional stability of articulated vehicles. Designing such a system demands a comprehensive knowledge of the reasons for the snaking phenomenon and driver behaviors. The results of our articulated vehicle directional stability investigation are presented. On this basis, we developed models of articulated vehicles with hydraulic steering systems and driver interaction. We next added the stabilizing system to the model. A simulation demonstrated the possibility of directional stability improvement. [ABSTRACT FROM AUTHOR]

The development of a methodology for calculating the designed strength of an unconventional kingpin-type load-carrying system for the articulated tractor container carrier on pneumatic wheels is an important and relevant task due to the unique layout of a given specialized vehicle. The purpose of this work is to devise a procedure for calculating the designed strength of a clip load-carrying system for the articulated tractor container carrier on pneumatic wheels, aimed at building an improved structure with rational metal consumption. The results of the theoretical and experimental studies have determined the most common estimation cases. They include the movement over the technological roads' irregularities along the horizontal section of the road ‒ an estimation case of the semi-trailer frame girders. climbing a high curb at an angle was also considered as an estimation case for the semi-trailer frame girders and cross member. Starting a tractor container carrier forward with an insurmountable obstacle in front of the semi-trailer's wheels was analyzed as an estimation case for the cross member of the frame and the suspension attachment units in the semi-trailer of a tractor container carrier. The result of the reported theoretical and experimental research is the determined load that acts on one cradle structure of the load-carrying system; it forms the torsional rigidity of the frame structure. Underlying the derived mathematical model for each case are the torsional moments and inertia moments that act on the structural elements of the girder in different planes. The mathematical models have been built on the basis of strength conditions for each estimation case and thus form a mathematical formula for determining the wall thickness of the frame girder. The mathematical notation demonstrates the degree of advantage of climbing a high curb at an angle over other estimation cases for the semitrailer frame member and girders. The estimation parameters underlying the mathematical model are meant to prevent the breaking and torsion of the semi-trailer frame in a tractor container carrier. [ABSTRACT FROM AUTHOR]

Development of compact and easy to use mathematical models of articulated vehicles for the motion planning, control, and localization purposes becomes more and more important in the era of intelligent transportation systems, especially when there exists a need of reliable predictions of motion for multi-body (semi-)automated freight and public transportation vehicles of various kinematic structures. We propose a modular algorithmic approach to kinematic modelling of nonholonomic (multi-)articulated buses, including the N-trailer vehicles as a special case, comprising a car-like prime-mover passively interconnected with arbitrary number of segments (wagons/trailers) equipped with fixed or steerable wheels, and with various locus of a driving axle in a kinematic chain. Kinematic models are valid under an assumption of a pure rolling of all the vehicle wheels (no skid/slip motion), which is practically justified for the low-speed maneuvering conditions. The proposed approach leads to compact nonlinear models which, thanks to their modular construction, preserve clear geometrical interpretation of velocity couplings between the vehicle segments. Derivations of kinematic models for popular structures of articulated and bi-articulated urban buses are presented for various driving-axle locus and steering capabilities. Experimental model validation, conducted with a full-scale wagon-driven articulated bus, illustrates utility of the approach. [ABSTRACT FROM AUTHOR]

A 16-degree-of-freedom non-linear roll dynamic model is developed for an articulated engineering vehicle considering non-linear road excitations and non-linear characteristics of vehicle structures. In addition, a variable step-size numerical method is proposed to solve the non-linear dynamic model. The proposed numerical method can improve the calculation accuracy and the computational stability. Through the proposed dynamic model, an equation is derived considering time-varying tire load characteristics to reflect the roll stability of an articulated engineering vehicle. Using the proposed roll stability equation, the driving stability can be effectively evaluated for an articulated engineering vehicle with different system parameters. The analysis results show that the roll stability decreases significantly with the increase in vehicle speed, centroid height of engineering vehicle, or lateral slope angle. The influence of vehicle speed and lateral slope angle on roll stability is greater than that of the centroid height of engineering vehicle. When steering on the road with a lateral slope angle, the roll angle and the lateral load transfer ratio curves fluctuate with time. As the lateral slope angle increases, the fluctuation is stronger. Overall, the proposed model can accurately evaluate the roll stability of a driving articulated engineering vehicle and accurately determine the unstable tilting of an articulated engineering vehicle. [ABSTRACT FROM AUTHOR]

Traditional articulated vehicles exhibit poor steering performance since there exist no direct rotating moment for the underactuated trailers, which cause such vehicles nearly cannot work well in the narrow space. To overcome this shortcoming associated with the traditional articulated vehicles, an active articulated structure is proposed, in which a steering motor is introduced at the articulated joint of tractor and trailer, in addition to utilizing mecanum wheels as trailer wheels. On the basis of this structure, a coordinated control method is designed to ensure the vehicle kinematics constraints and dynamic maneuverability. The coordination control consists of two level controllers. On the level of kinematics, model predictive control (MPC) is adopted as posture controller, which can solve the non-holonomic problem of the whole active articulated tractor-trailer vehicle system; On the dynamic level, a sliding mode control (SMC) is introduced to design a dynamic controller to track the desired velocities generated online, which can increase the robustness of the system. The simulation results show that the proposed active articulated tractor-trailer vehicle system has better maneuverability compared with the traditional one, and the proposed control strategy can ensure the required control effect. [ABSTRACT FROM AUTHOR]

Brake time delay, which is a major shortcoming of air brake systems, may lead to precarious situations. In this study, the structure of an air brake system of a tractor–semitrailer was optimized by adding a shuttle valve and a two-position-three-port electromagnetic valve between the control pipeline and the charging pipeline downstream of the trailer control valve. The new electronically controlled structure clearly ensures that the semitrailer brakes faster, as validated by a simulation, bench test, and real-vehicle test. The simulation results reveal considerable improvements in the braking time, braking distance, longitudinal kinetic energy, lateral kinetic energy, and β phase plane. The bench test indicates that in the proposed structure, the average response time of service brake cylinders of the first and third axles of the semitrailer are 0.12 and 0.17 s, respectively. In addition, the real-vehicle test indicated that the service brake cylinders of the first and third axles responded 0.12 and 0.18 s earlier than those in the original system, respectively. [ABSTRACT FROM AUTHOR]

Due to the large lateral area of the trailer and variable road conditions, the handling stability of a heavy tractor semi-trailer under crosswind is very important for road safety. In this present work, numerical simulation is performed to study the crosswind effects on handling stability of a tractor semi-trailer. The aerodynamic characteristics of the tractor semi-trailer under different crosswind were computed by computational fluid dynamics (CFD). Then, mathematical models to reveal the relationship between the aerodynamic forces and crosswind were constructed to serve as inputs of the multi-body dynamics to analyze the handling stability under crosswind. The performance of crosswind stability is evaluated by the response of lateral acceleration, yaw rate and the lateral displacement. The lateral acceleration and yaw rate were decreased by a maximum of 14.6% and 16.5% compared to the truck without the deflector, which showed that the crosswind aerodynamics and stability were obviously improved. [ABSTRACT FROM AUTHOR]

An articulated frame steered vehicle model with torsio-elastic suspension is established in Adams/View. The model considered the influence of the hydraulic steering system on the yaw stability of articulated vehicles, thus, the hydraulic steering system is formulated and modeled in MATLAB/Simulink. The ride and roll/yaw stability of the vehicle model is investigated via co-simulation of Adams and Simulink. The Adams vehicle model is verified based on the vibration acceleration responses near the seat position at constant forward speeds. The hydraulic steering system model is validated through the steady-state steering maneuver. Relative ride performance of unsuspended and fully suspended vehicle is investigated in terms of unweighted and frequency-weighted root-mean-square accelerations. The roll and yaw stability of vehicle model with and without suspension at loaded and unloaded conditions are subsequently analyzed in terms of roll angle, roll safety factor, lateral acceleration, critical speed, and so on. The results show that the torsio-elastic suspension can efficiently reduce the vibrations of the vehicle, and the articulated frame steer vehicles applied with torsio-elastic suspension yield slightly lower roll/yaw stability but substantial reductions in the ride vibration levels. The results provide some reference for the suspension and steering system design of articulated engineering vehicle. [ABSTRACT FROM AUTHOR]

This paper proposes a gain-scheduled controller synthesis for improving the lateral performance and stability of articulated heavy vehicles by active steering of the selected towed vehicle units. The longitudinal velocity is on-line measurable, and it is thus treated as a scheduling parameter in the gain-scheduled controller synthesis. The lateral performance of four articulated heavy vehicles, including existing Nordic heavy vehicles and prospective longer articulated heavy vehicles, are investigated with and without active steering and compared with a commonly used conventional tractor–semitrailer. The control problem is formulated as an H ∞ static output feedback, which uses only information from articulation angles between the steered vehicle unit and the vehicle unit in front of it. The solution of the problem is obtained within the linear matrix inequality framework, while guaranteeing H ∞ performance objectives. Effectiveness of the designed controller is verified through numerical simulations performed on high-fidelity vehicle models. The results confirm a significant reduction in yaw rate rearward amplification, lateral acceleration rearward amplification, and high-speed transient off-tracking, thereby improving the lateral stability and performance of all studied heavy vehicles at high speeds. [ABSTRACT FROM AUTHOR]

The rock pressure appearance of longwall faces in shallow seams is generally violent, and roofs and supports are susceptible to damage during equipment extraction. Stability control of the rock surrounding longwall recovery roadways allows safe and rapid equipment extraction. Herein, via theoretical analysis, numerical simulations, and field observations, the stability control of the rock surrounding recovery roadways is studied to ensure the release of the accumulated rock pressure on the roof, the working resistance of the supports and the reasonableness of the recovery roadway support design. Pressure-relief technology is introduced to release the accumulated rock pressure before equipment extraction, and a discriminative approach is proposed to determine the breaking and articulated forms of key strata and broken blocks, respectively. On this basis, mechanical models of roof instability are established based on four key stratum structures in the overburden of shallow seams. Methods for calculating a reasonable working resistance for supports are discussed. Finally, Liangshuijing Coal Mine and Fengjiata Coal Mine are taken as research objects to evaluate the roof stability of recovery roadways based on observations of weighting characteristics. The support working resistances and reasonable recovery roadway widths under three key stratum structures are determined. Considering the time effect of plastic zone development, the support design of recovery roadways is optimized. FLAC2D software simulates the surrounding rock control effect of two support designs, and roof subsidence curves are obtained. The results show that the key to equipment extraction in shallow seams is to ensure that supports have reasonable working resistances and to improve the support of recovery roadways. The results provide a reference for the selection and extraction of supports in shallow seam faces. [ABSTRACT FROM AUTHOR]

The special steering characteristics and task complexity of autonomous articulated vehicle (AAV) make it often require multiple forward and backward movements during autonomous driving. In this paper, we present a simple yet effective method, named head correction with fixed wheel position (HC-FWP), for the demand of multiple forward and backward movements. The goal-directed rapid-exploring random tree (GDRRT) algorithm is first used to search for a feasible path in the obstacle map, and then, the farthest node search (FNS) algorithm is applied to obtain a series of key nodes, on which HC-FWP is used to correct AAV heading angles. Simulation experiments with Dynapac CC6200 articulated road roller parameters show that the proposed improved goal-directed rapid-exploring random tree (IGDRRT), consisting of GDRRT, FNS, and HC-FWP, can search a feasible path on maps that require the AAV to move back and forth. [ABSTRACT FROM AUTHOR]

Articulated steering vehicles have outstanding capability operating but suffer from frequent rollover accidents due to their complicated structure. It is necessary to accurately detect their rollover risk for drivers to take action in time. Their variable structure and the variable center of mass exhibit nonlinear time-variant behavior and increase the difficulty of dynamic modelling and lateral stability description. This paper proposes a novel data-driven modelling methodology for lateral stability description of articulated steering vehicles. The running data is first collected based on the typical operations that prone to rollover and then classified into two types: Safety and danger. The data quality is further improved by wavelet transformation. Finally, an RNN model is built on the data. The experimental results show that the output of the RNN model can accurately quantify lateral stability of the vehicle, i.e., the risk of rollover, when it is turning and crossing uneven surfaces or obstacles. [ABSTRACT FROM AUTHOR]