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Design and Optimization of a Robust Active Trailer Steering System for Car-Trailer Combinations

University of Ontario Institute of Technology-Mutaz Keldani, Khizar Qureshi, Yuping He, Ramiro Liscano
Published 2019-04-02 by SAE International in United States
This paper presents a robust active trailer steering (ATS) controller for car-trailer combinations. ATS systems have been proposed and explored for improving the lateral stability and enhancing the path-following performance of car-trailer combinations. Most of the ATS controllers were designed using the linear quadratic regulator (LQR) technique. In the design of the LQR-based ATS controllers, it was assumed that all vehicle and operating parameters were constant. In reality, vehicle and operating parameters may vary, which may have an impact on the stability of the combination. For example, varied vehicle forward speed and trailer payload may impose negative impacts on the directional performance of the car-trailer combination. Thus, the robustness of the conventional LQR-based ATS controllers is questionable. To address this problem, we propose a gain-scheduling LQR-based ATS controller. In the design of the proposed ATS controller, at each operating point, the ATS controller is designed using the LQR technique. At an operating point between two established adjacent operating points, the control gain matrix of the controller is determined using an interpolation method. To further improve…
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Safety and Lateral Dynamics Improvement of a Race Car Using Active Rear Wing Control

University of Ontario Institute of Technology-Mohammed Hammad, Khizar Qureshi, Yuping He
Published 2019-04-02 by SAE International in United States
As the forward speed of a car increases, the safety of the vehicle and the driver becomes a more significant concern. Active aerodynamic control can effectively enhance the lateral stability of high speed vehicles over tight cornering maneuvers. A split rear wing has been proposed. By means of manipulating the attack angles for the right and/or left parts of the split rear wing, a favorable yaw moment may be achieved to ensure the lateral stability of the vehicle. However, active control of the split rear wing has not been adequately explored. This paper proposes a novel active split rear wing, which can improve the lateral stability over tight cornering maneuvers, and will not degrade the longitudinal dynamics of the vehicle. A Linear Quadratic Regulator (LQR) based controller for the active split rear wing is designed using a linear vehicle model. In order to examine the performance of the active split rear wing, Numerical simulation is carried out using the LQR based controller and a yaw-plane vehicle model designed in MATLAB. The effectiveness of the proposed…
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A Review of Car-Trailer Lateral Stability Control Approaches

University of Ontario Institute of Technology-Smitha Vempaty, Yuping He
Published 2017-03-28 by SAE International in United States
Ensuring the lateral stability and handling of a car-and-trailer combination remains one of the challenges in safety system design and development for articulated vehicles. This paper reviews the state-of-the-art approaches for car-trailer lateral stability control. A literature review covering the effects of external factors, such as aerodynamic forces, tire forces, and road & climatic conditions, is presented. To address the effects of these factors, researchers have previously investigated numerous passive and active safety control techniques. This paper intends to identify the inadequacies of the passive safety approaches and analyzes promising active-control schemes, such as active trailer steering control (ATSC), active trailer braking (ATB) and model reference adaptive controller (MRAC). A comparative study of these control strategies in terms of applicability and cost effectiveness is performed.
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Effects of Active Aerodynamic Wings on Handling Performance of High-Speed Vehicles

Univ. of Ontario Institute of Technology-Jingdong Cai, Saurabh Kapoor, Tushita Sikder, Yuping He
Published 2017-03-28 by SAE International in United States
In this research, active aerodynamic wings are investigated using numerical simulation in order to improve vehicle handling performance under emergency scenarios, such as tight cornering maneuvers at high speeds. Air foils are selected and analyzed to determine the basic geometric features of aerodynamic wings. Built upon the airfoil analysis, the 3-D aerodynamic wing model is developed. Then, the virtual aerodynamic wings are assembled with the 3-D vehicle model. The resulting 3-D geometry model is used for aerodynamic analysis based on numerical simulation using a computational fluid dynamics (CFD) software package. The CFD-based simulation data and the vehicle dynamic model generated are combined to study the effects of active aerodynamic wings on handling performance of high-speed vehicles. The systematic numerical simulation method and achieved results may provide design guidance for the development of active aerodynamic wings for high-speed road vehicles.
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Non-Linear Bifurcation Stability Analysis for Articulated Vehicles with Active Trailer Differential Braking Systems

SAE International Journal of Materials and Manufacturing

University of Ontario Institute of Technology-Tao Sun, Eungkil Lee, Yuping He
  • Journal Article
  • 2016-01-0433
Published 2016-04-05 by SAE International in United States
This paper presents nonlinear bifurcation stability analysis of articulated vehicles with active trailer differential braking (ATDB) systems. ATDB systems have been proposed to improve stability of articulated vehicle systems to prevent unstable motion modes, e.g., jack-knifing, trailer sway and rollover. Generally, behaviors of a nonlinear dynamic system may change with varying parameters; a stable equilibrium can become unstable and a periodic oscillation may occur or a new equilibrium may appear making the previous equilibrium unstable once the parameters vary. The value of a parameter, at which these changes occur, is known as “bifurcation value” and the parameter is known as the “bifurcation parameter”. Conventionally, nonlinear bifurcation analysis approach is applied to examine the nonlinear dynamic characteristics of single-unit vehicles, e.g., cars, trucks, etc. Little attention has been paid to investigate the feasibility and effectiveness of the bifurcation analysis method for nonlinear stability analysis of articulated vehicles under varied operating conditions, e.g., varied forward speed and trailer payload. This motivates the research to examine stability boundaries of equilibrium and limit cycles in the parameter space and…
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Model Reference Adaptive Control for Active Trailer Steering of Articulated Heavy Vehicles

Univ. of Ontario Institute of Technology-Qiushi Wang, Shenjin Zhu, Yuping He
Published 2015-04-14 by SAE International in United States
This paper proposes a model reference adaptive control (MRAC) strategy for active trailer steering (ATS) in order to improve the lateral stability of articulated heavy vehicles (AHVs). Optimal controllers based on the Linear Quadratic Regulator (LQR) technique have been explored to enhance the lateral stability of AHVs; these controllers are designed under the assumption that the vehicle model parameters and operating conditions are given and they remain as constants. However, in reality, the vehicle system parameters and operating conditions may vary. To address the variable payloads of trailer(s), the controller based on MRAC technique is adopted. A three degrees of freedom (DOF) linear yaw-plane tractor-semitrailer model is generated to design the control law. The reference model is also developed using the linear yaw-plane model with the LQR technique. The effectiveness of the MRAC controller is demonstrated using numerical simulations under an emulated single lane-change maneuver.
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Phase-Plane Analysis for Evaluating the Lateral Stability of Articulated Vehicles

Univ. of Ontario Institute of Technology-Tao Sun, Yuping He
Published 2015-04-14 by SAE International in United States
The phase-plane analysis technique has become a powerful tool for analyzing lateral stability of single-unit vehicles. Articulated vehicles, such as car-trailer combinations, consist of multiple vehicle units. Multi-unit vehicles exhibit unique dynamic features compared against single-unit vehicles. For example, a car-trailer may exhibit one of the three unstable motion modes, i.e., jack-knifing, trailer sway and rollover. Considering the distinguished configurations and dynamic features of articulated vehicles, it is questionable whether the phase-plane analysis method based on single-unit vehicles is applicable for analyzing the lateral stability of multi-unit vehicles. In order to address the problem, case studies are conducted to test the effectiveness of the phase-plane method for analyzing the lateral stability of a car-trailer combination, which is represented by a nonlinear vehicle model generated using the CarSim software package. The phase-plane analysis, which examines the relation between the leading unit's side-slip angle and side-slip angular velocity (β − dβ/dt), the relation between the trailing unit's side-slip angle and side-slip angular velocity (β′ − dβ′/dt), and the interrelation of the side-slip angle of the leading unit,…
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Dynamics Analysis of Car-Trailer Systems with Active Trailer Differential Braking Strategies

SAE International Journal of Passenger Cars - Mechanical Systems

Univ. of Ontario Institute of Technology-Tao Sun, Yuping He, Jing Ren
  • Journal Article
  • 2014-01-0143
Published 2014-04-01 by SAE International in United States
To date, various control strategies based on linear vehicle models have been researched and developed for improving lateral stability of car-trailer (CT) systems. Is a linear-model-based controller applicable to active safety systems for CT systems under emergency operating conditions, such as an evasive maneuver at high lateral accelerations? In order to answer the question, the applicability of an active trailer differential braking (ATDB) controller designed using a linear CT model is tested and evaluated, while the controller being applied to a CT system represented by a linear and a nonlinear CT model. The current research leads to the following insightful findings: the ATDB controller designed using the linear model can effectively improve the lateral stability of CT systems under regular evasive maneuvers at low lateral accelerations, but the controller is not applicable to CT active safety systems under emergency evasive maneuvers at high lateral accelerations. The insightful findings resulted from the paper will provide valuable design guidelines for the development of active safety systems for CT systems.
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A Comparative Study of Car-Trailer Dynamics Models

SAE International Journal of Passenger Cars - Mechanical Systems

Univ of Ontario Institute of Technology-Yuping He, Jing Ren
  • Journal Article
  • 2013-01-0695
Published 2013-04-08 by SAE International in United States
The paper examines typical vehicle dynamics models used for the design of car-trailer active safety systems, including active trailer braking and steering. A linear 3 degree-of-freedom (DOF), a nonlinear 4 DOF and a nonlinear 6 DOF car-trailer model are generated. Then, these models are compared with a car-trailer model developed with the commercial software package, CarSim. The benchmark investigation of the car-trailer models is carried out through examining numerical simulation results obtained in two emulated tests, i.e., a single lane-change and a Fishhook maneuver. In the vehicle modeling, a mathematical model of a tire with flexible sidewalls is included to account for transient tire forces. Steady-state aerodynamic forces are included in these models. The deviation of the model dynamic responses, e.g., the variation of the articulation angle between the car and trailer, is discussed. With the benchmark investigation, the car-trailer models in terms of fidelity, complexity, and applicability for active safety system design are addressed.
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Design of an Actively Controlled Aerodynamic Wing to Increase High-Speed Vehicle Safety

Univ. of Ontario Institute of Technology-Yuping He
Published 2013-04-08 by SAE International in United States
This paper presents the design of airfoil and briefly introduces a real physical prototype for an actively controlled wing to improve high speed vehicle safety. Conventionally, active safety systems of road vehicles, including active steering and differential braking, mainly manipulate the tire/road forces to enhance the lateral stability of vehicles. However, this active safety technology is hindered by the saturation of tire/road forces at high lateral accelerations and on icy slippery roads. In contrast, the use of controlled aerodynamic forces has received little attention. In this paper, the actively controlled wing is proposed to manipulate the negative lift force (downforce) to enhance handling capabilities of vehicles at high speeds. Various wings are examined in terms of airfoil shapes, coefficient of drag and lift, resulting yaw/roll moments, effect of wing attack angle at different Reynolds numbers using numerical simulations with X-Foil, Gambit and Fluent software packages. A prototype of the proposed actively controlled wing is briefly introduced. The essential design parameters, functionality and features of the active wing are addressed. In a companion paper that will…
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