Vehicle Handling Stability Research Articles

Design and research of face gear central limited slip differential and analysis of its influence on vehicle performance

In this paper, a new design scheme of face gear central limited-slip differential (F-LSD) is proposed, which aims to unveil the technical veil of central limited-slip differential and fill the research blank of face gear application in the field of central limited-slip differential. Through the analysis of structural principle and motion characteristics, the dynamic equilibrium equation and locking coefficient model of F-LSD are established. The Simulink simulation model based on F-LSD dynamics and the torque distribution model of the whole transmission system are established. A 7-DOF vehicle dynamics model was established, and the performance of F-LSD vehicle in four conditions of acceleration, climbing, chassis twist sine wave and double line change was studied by using simulation software. At the same time, four groups of four-wheel drive vehicles with different central differential speeds were set as the control test group. The simulation results show that F-LSD system can effectively improve the vehicle's dynamic performance and extrication performance, and will not reduce the vehicle's handling stability, which provides a reference for the practical application of the face gear central limited slip differential.

Research on optimization of the vehicle handling stability considering flexibility of the front subframe

The elastic deformation of the front subframe during vehicle traveling affects the vehicle handling stability. The static equilibrium equations of the suspension and subframe system and the kinematics equations of the three-degree-of-freedom vehicle are established to illustrate the principle of the influence of the flexible front subframe on the handling stability. The front subframe is flexibly processed to establish a rigid-flexible coupled vehicle model. Simulations of the suspension kinematic and compliance alongside sine swept steering simulation of the vehicle are performed. The front subframe bushing stiffness, which has a greater impact on the handling stability, is selected as a design variable through parametric test design, and the NSGA-II algorithm is used for multi-objective optimization with the vehicle handling stability evaluation index as the optimization target. The simulation results show that the flexible front subframe will make the bushing force change to affect the suspension kinematic and compliance characteristics and then affect the vehicle handling stability, the gain of vehicle yaw rate and the delay time of lateral acceleration decrease, while the gain of roll angle increases. The optimization results show that the optimized vehicle exhibits improvements in the yaw rate gain, delay time of lateral acceleration, and roll angle gain.

Modelling and experimental validation of an adaptive interconnected suspension with adjustable roll stiffness (AIS-ARS)

Vehicle suspensions play a critical role in improving vehicle stability and ride quality, especially in heavy vehicles that usually have high centre-of-gravity and carry tons of cargo. Interconnected suspension systems, in which the suspension struts are connected through hydraulic hoses and flow control devices, have great potential to enhance vehicle handling stability and attenuate vibrations. This study introduces an adaptive interconnected suspension with adjustable roll stiffness (AIS-ARS) to address the shortcomings of existing designs. It not only eliminates the conventional anti-roll bars but also enables adjustment of roll stiffness depending on the driving and vehicle load conditions. The AIS-ARS system uses a unique design that avoids using expensive electro-proportional flow control valves, which has been a significant barrier to widespread implementation. Instead, the system utilises a cost-effective control strategy that uses only two solenoid valves to achieve adaptive damping. The mathematical modelling of the AIS-ARS is also straightforward, requiring less computational power and making it more practical for real-time implementations. Overall, the AIS-ARS system represents a significant advancement in the design of interconnected suspension systems, offering a more cost-effective, practical, and versatile solution. The above features are validated through laboratory experiments and co-simulation between MATLAB/Simulink and ADAMS/Car.

Distributed Drive Electric Vehicle Handling Stability Coordination Control Framework Based on Adaptive Model Predictive Control.

Distributed drive electric vehicles improve steering response and enhance overall vehicle stability by independently controlling each motor. This paper introduces a control framework based on Adaptive Model Predictive Control (AMPC) for coordinating handling stability, consisting of three layers: the dynamic supervision layer, online optimization layer, and low-level control layer. The dynamic supervision layer considers the yaw rate and maneuverability limits when establishing the β-β˙ phase plane stability boundary and designs variable weight factors based on this stability boundary. The online optimization layer constructs the target weight-adaptive AMPC strategy, which can adjust the control weights for maneuverability and lateral stability in real time based on the variable weight factors provided by the dynamic supervision layer. The low-level control layer precisely allocates the driver's requested driving force and additional yaw moment by using torque distribution error and tire utilization as the cost function. Finally, experiments are conducted on a Simulink-CarSim co-simulation platform to assess the performance of AMPC. Simulation results show that, compared to the traditional MPC strategy, this control strategy not only enhances maneuverability under normal conditions but also improves lateral stability control under extreme conditions.

Application Of Onboard PIV To Front Wheelhouse Wake Behavior Under Stationary Crosswind Conditions

When driving a car, the driver and passengers may feel larger drag from a headwind, the steering wheel would be taken away by a crosswind or pushed by a tailwind. Anytime, anywhere, we will encounter various scenes with natural wind under real world conditions such as urban, suburb and highway. We will develop the appropriate vehicle by simulating these conditions to satisfy with various customer requirements. For vehicle aerodynamic research and development, we are simply running simulations in physical- and cyber-space, that is, wind tunnel facility and computational fluid dynamics to reproduce these real worlds. However, it is not easy to simulate these wind inlet conditions, such as the temporal change in crosswind, especially, in wind tunnel facility. The stationary yaw angle by rotating turntable would reproduce a crosswind, if there is no turbulent generator system like in Pininfarina and Swing in FKFS. Therefore, we focus on the unsteady and asymmetrical flow from the front wheelhouse of the vehicle with tire rotation. There is three-dimensional complicated flow that are interacted by the flow from various directions, such as the flow along the front bumper, the flow along the rotating tire and wheel, the blowing flow from the rotating wheel opening area and the flow from the tire house. These complicated flow produces the front wheelhouse wake along the body side that affects the vehicle aerodynamic performance. Furthermore, there are asymmetrical flows around the vehicle by different front wheelhouse wake in windward and leeward sides. The larger side wake increases the aerodynamic drag, and the fluctuating side wake may induce the instability of the vehicle handling stability. Here, the proposed onboard 2D-3C PIV measurement system in the previous study enables us to measure same measurement area along the vehicle body side without change in optical configuration effectively, that indicates to reduce the time by resetting the optical configuration. We will investigate what kind of flow field should be focused on and controlled to prevent the vehicle instability by investigating these asymmetrical flow field around the vehicle under crosswinds.

Research on lateral stability control strategy for distributed drive electric vehicles considering driving style

To improve the handling stability of distributed drive electric vehicle (DDEV), a lateral stability control strategy considering driving style is proposed. Firstly, a driving style recognition model based on support vector machines (SVM) was constructed to identify driving styles in different lateral motion scenarios. Then, a layered architecture is used to design a driver/Active Front Steering (AFS)/Direct Yaw Control (DYC) stability coordination control strategy. The upper layer is based on the phase plane of the sideslip angle and extension control theory, dividing the vehicle operating range into classical, extension, and non domains. In the middle level, three control strategies are designed for different work domains. In the classical domain, a driver/AFS coordinated control strategy based on non-cooperative Nash games is constructed, and the weight coefficients in the AFS system cost function are modified based on driving characteristics; Construct a coordinated control strategy for AFS/DYC systems based on cooperative Pareto games in the extension domain; In non-domain, construct a direct yaw torque control strategy based on twin-delayed deep deterministic policy gradient (TD3) reinforcement learning. The lower layer aims to minimize tire utilization and optimizes the allocation of additional yaw moment. Finally, by establishing Hardware in the Loop (HIL) experiment platform, the effectiveness of the proposed control strategy is verified in lane changing scenarios of different styles of drivers. Compared to DYC stability control based solely on TD3, the maximum yaw rate and standard deviation of the lateral stability control strategy considering driving style reduce by 2.4 % and 10.82 %, respectively, and the maximum and standard deviation of the sideslip angle reduce by 29.29 % and 39.24 %, respectively, thereby improving the vehicle's handling stability.

Distributed-Drive Vehicle Lateral-Stability Coordinated Control Based on Phase-Plane Stability Region

The lateral stability control of vehicles is one of the most crucial aspects of vehicle safety. This article introduces a coordinated-control strategy designed to enhance the handling stability of distributed-drive electric vehicles. The upper controller uses active front steering and direct yaw moment-control controllers designed based on sliding-mode control theory. The lower controller optimally allocates control inputs to the upper controller, considering factors such as load transfer and tire load rate. It divides the stability region by relying on the phase plane and develops a coordinated-control strategy based on the degree of deviation of the vehicle state from the stability region. The results of the simulation experiments demonstrate that the proposed control strategy effectively improves handling stability under extreme working conditions.

Hierarchical extension H2/H∞ control approach for active front steering system of vehicle

Aiming at improving the vehicle handling stability and vehicle control performance by conventional H2/H∞ control, this paper investigates the active front steering (AFS) system by proposing a hierarchical extension H2/H∞ control strategy. Considering uncertainties and the vehicle handling stability, a mixed H2/H∞ control method is presented to generate the additional front wheel angle through tracking the desired vehicle yaw rate in the upper level. Furthermore, to enhance the H2/H∞ control effect, the novel extension control is proposed to adjust the H2/H∞ control signal dynamically according to different domains defined by the vehicle states. To track front wheel angle from the upper level, this study puts forward the fractional-order proportional-integral-derivative (FOPID) controller for driving the electro-hydraulic steering actuators. The hardware-in-the-loop experiments are performed to demonstrate the hierarchical control theory. The test results indicate that the proposed hierarchical extension H2/H∞ control strategy improves the vehicle cornering stability well, as well as can make the vehicle have better handling stability than conventional H2/H∞ and sliding mode control.

Coordinated Longitudinal and Lateral Motion Control for Distributed Drive Electric Vehicles With Mechanical Elastic Wheels

The distributed drive electric vehicle (DDEV) with active front wheel steering is an over-actuated system. For such a system, more optimization targets should be considered to make the system better in addition to meeting the driving command of drivers and keeping the vehicle stable. The slip energy generated by excessive tire slipping reduces the utilization of the output energy of the motor, resulting in a reduction of electric vehicle mileage. In order to improve the vehicle performance, a coordinated longitudinal and lateral controller is designed for DDEV with mechanical elastic wheels (MEWs). The motion control layer of the hierarchical controller adopts the integral sliding mode control (ISMC) to determine the desired longitudinal force, lateral force and yaw moment as virtual inputs of the vehicle. Then, a novel tire force distribution strategy is proposed to dynamically assign the virtual inputs among front wheels and four motors with the goal of optimizing the vehicle stability and longitudinal tire slip energy dissipation. To characterize tire slip energy more accurately, the brush model matching MEW is deduced in the combined slip conditions. The proposed controller is evaluated on the hardware-in-the-loop (HIL) test platform under different driving conditions. Simulation results demonstrate that this controller not only ensures the vehicle handling stability performance, but also improves the utilization of motor output energy and reduces tire wear.

Improved sliding mode extension control of vehicle active front wheel steering based on extended state observer

In order to improve the handling stability of electric vehicles, a new active front-wheel steering (AFS) control method was proposed. Firstly, parametric uncertainty and external interference in vehicle dynamics are summarized as a nonlinear interference term in vehicle model. An extended state observer (ESO) is designed to observe and compensate the nonlinear interference terms in real time, so as to improve the accuracy and control effect of the model. Secondly, in order to further increase the convergence speed and effectively suppress the chattering phenomenon in sliding mode control without affecting its robustness and reaching speed, an integral exponential fast terminal sliding mode controller (IEFTSMC) based on fast exponential reaching law (FERL) is designed. The problem that the control effect of some regions becomes worse when a single control algorithm is used for global region control in traditional AFS control is addressed. By combining extension theory with sliding mode control method, an improved sliding mode extension control is designed to improve the effect of AFS global control. Finally, comparative simulation tests are carried out on the CarSim/Simulink co-simulation platform. The results show that compared with the traditional FTSMC, the improved sliding mode extension control method based on ESO can not only suppress chattering more effectively, but also smoother the response curve. It also has good control effect when there is external disturbance. The effectiveness and robustness of the control strategy are verified.

Rule-based torque vectoring distribution strategy combined with slip ratio control to improve the handling stability of distributed drive electric vehicles

This study presents a hierarchical control system of handling stability for distributed drive electric vehicles. The desired direct yaw moment (DYM), determined by the upper-level controller, regulates the sideslip angle and yaw rate according to the robust H∞ control strategy. Meanwhile, the lower-level controller proposed in this research consists of a rule-based torque vectoring distribution and wheel slip ratio control. The proposed rule-based torque vectoring distribution strategy (TVDS) permits drive pattern switching based on the wheel slip ratio and preferentially employs the balanced torque vectoring distribution strategy to achieve DYM, wherein the distributed braking torque is achieved by motor regenerative braking. Here, the wheel with serious slipping was managed in a four-wheel drive pattern by the slip ratio controller. Then, the distribution strategies used for differential braking and proposed rule-based torque vectoring with and without slip ratio control were compared and analyzed in vehicle states and actuator outputs, respectively, by setting CarSim/MATLAB cosimulation under two driving conditions. Results demonstrate that the proposed rule-based TVDS can improve handling stability, energy efficiency, and riding comfort. Wheel locking can be successfully avoided by actuating the wheel slip ratio control, subsequently reducing the road adhesion requirements and improving vehicle handling stability and trajectory tracking accuracy.

Notice of Violation of IEEE Publication Principles: Integrated Control of Braking and Steering Subsystems for Autonomous Vehicle based on an Efficient Yaw Moment Distribution

Notice of Violation of IEEE Publication Principles Control of Braking and Subsystems for Autonomous Vehicle based on an Efficient Yaw Moment by Shaobo Lu, Sheng Cen, Xiaosong Hu, Cheewah Lim and Jinlong Zhang, in the IEEE Transactions on Industrial Electronics, Early Access, May 2017 After careful and considered review of the content and authorship of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE’s Publication Principles. This paper copies equations from the paper(s) cited below. The content was copied without attribution (including appropriate references to the original author(s) and/or paper title) and without permission. The lead and the second author of the paper were responsible for the violation. A correction letter for this misconduct was submitted and published at http://ieeexplore.ieee.org/document/8017449 Coordinated Control with Electronic Stability Control and Active Front Using the Optimum Yaw Moment Distribution Under a Lateral Force Constraint on the Active Front Steering by Seongjin Yim, Seungjun Kim and Heesung Yun, in the Proceedings of Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2016, Vol. 230(5) pp. 581-592 This paper presents an Integrated Chassis Control (ICC) strategy for Electronic Stability Control (ESC) and Active Four Wheel (AFWS) based on an efficient optimal yaw moment distribution. To further enhance the handling and lateral stability of vehicle equipped with ESC, a new Weighted Pseudo- inverse Control Allocation (WPCA) based ICC is proposed. The cornering forces of both front and rear wheels are used to cooperate with the ESC braking forces, so as to further extend the operational envelope of the vehicle. A bi-level hierarchical control structure is employed. In the upper level, the sliding mode control with a combined sliding surface is used to generate the desired virtual control. In the lower level, a revised optimal function is defined to tune the control authority of actuators, and an algebraic operation based WPCA method is adopted. To avoid tire forces saturation and enforce a certain stability margin, a boundary layer constraint is further considered in the proposed optimization problem. A severe lane change maneuver is used to investigate the performance via closed-loop driver-vehicle- controller simulations using CarSim and MATLAB/Simulink. Simulation results demonstrate that the proposed algorithm outperforms current control practice without violating the actuators physical limitation.

A novel conservative dynamics envelope of vehicle lateral stability under different tire characteristics

This paper proposes a dynamic stability envelope based on safety maneuver margin to estimate the lateral stability of nonlinear vehicle systems with different tire characteristics (i.e. understeering (UN) and oversteering (OV) vehicles). Firstly, this study employs phase portraits and handling diagrams to investigate the number of equilibrium points and the evolution trend of state variables under various manipulation conditions. Subsequently, the nonlinear bifurcation theory is applied to analyze the characteristics of the vehicle equilibrium, aiming to derive the safe maneuver margin of the vehicle and restrict the vehicle instability. Within this proposed margin, the stability of each point of the nonlinear system is analyzed using the local linearization method. Simultaneously, a more conservative estimate of the vehicle handling stability is further obtained by applying stability criteria, resulting in the dynamic stability envelope, which ensures vehicle stability. Finally, the reliability of the dynamic stability envelope results based on the safety maneuver margin is validated under sine-with-dwell conditions (SDC) and steady-state cornering driving scenarios (SSC). The simulation results indicate that maintaining an appropriate understeering range keeps the vehicle stable.

Integrated control of path tracking and handling stability for autonomous ground vehicles with four-wheel steering

Accurate modelling of an autonomous ground vehicle (AGV) is challenging due to strong nonlinearity, model perturbations and external disturbances. This necessitates the design of path tracking controllers with robustness. In this paper, an integrated control strategy for path tracking and handling stability of AGVs is proposed, leveraging a four-wheel steering (4WS) system. To address the path tracking problem, a fuzzy logic-based steering strategy is developed, which enables parameter self-adjustment based on displacement error. Additionally, a reference model is employed to transform the path tracking problem into a reference signal tracking problem, ensuring the handling stability of vehicles. A sliding mode controller is designed to track the reference signal, utilizing an extended state observer to estimate and compensate for unmodeled dynamics and unknown external disturbances in real-time. Simulation results demonstrate the effectiveness of the proposed strategy in accurately tracking the desired path while maintaining the lateral stability of the vehicle. Furthermore, the strategy exhibits strong robustness against uncertainties and disturbances.

Research on Collaborative Control of Differential Drive Assisted Steering and Active Front Steering for Distributed Drive Electric Vehicles

A collaborative control strategy for distributed drive electric vehicles (DDEVs) focusing on differential drive assisted steering (DDAS) and active front steering (AFS) is proposed to address the issues of sudden torque changes, reduced steering characteristics, and weak collaborative control capabilities caused by the coupling of the AFS and DDAS systems in DDEVs. This paper establishes a coupled dynamic model of the AFS and DDAS systems and, on this basis, designs AFS controllers for yaw velocity feedback control and DDAS controllers for steering wheel torque control, respectively. Additionally, it analyzes the interference factors of the two control systems and develops a collaborative control strategy for DDAS and AFS; this control strategy establishes a corner motor correction module, steering wheel torque correction module, and assistance correction module. Co-simulation is carried out on Matlab/Simulink and the Carsim platform to verify the correctness of the model under typical working conditions; to reduce the sudden change in the steering wheel torque caused by AFS additional angle interventions; to improve the poor steering characteristics caused by DDAS, introducing additional yaw torque; to greatly enhance the collaborative control effect; and to meet the requirements for vehicle handling stability, portability, and safety.

Multi-objective optimization design of magnetorheological damper and vehicle handling stability performance research

Due to the characteristics of smart material magnetorheological (MR) fluid, such as short response time and large controllable range, semi-active suspension based on MR fluid has been widely used. In order to improve the steering stability of vehicles, a semi-active suspension with tapered flow mode MR was proposed. The magnetic circuit of the proposed structure was designed, its dynamic model was established, and the finite element simulation analysis was carried out. By establishing the optimization objectives and constraints, the MR damper was optimized by NSGA-II and MOST algorithms. The vehicle dynamics model with MR damper was established, and the vehicle dynamics simulation was carried out under the control system based on the vehicle dynamics simulation software CarSim-Simulink before and after optimization. The results show that the NSGA-II optimized MR damper can reduce vehicle roll and significantly improve vehicle handling stability. This paper provides a new idea for improving vehicle handling stability by optimizing the MR damper.

An Energy-Oriented Torque-Vector Control Framework for Distributed Drive Electric Vehicles

The over-actuated characteristics of distributed drive electric vehicles (DDEVs) provide a flexible platform to pursue higher holistic performance. This paper proposes a dual-model predictive control (MPC)-based hierarchical framework to realize the energy saving while improving the handling stability for DDEVs. The upper layer allocates the torque vector through the front/rear axles, which can provide a high-efficiency zone for the in-wheel motors and reduce the energy consumption. The lower layer generates a direct-yaw-moment control input by differential longitudinal forces of the left/right wheels to ensure the vehicle handling stability. Considering the time-varying state variables, a linear-time-varying model-predictive-control (LTV-MPC) method is adopted to guarantee the accuracy of the model. The combined magic formula tire model is used to modify the tire parameters, including tire longitudinal stiffness and cornering stiffness. The soft constraint constructed by β-γ phase plane is introduced in the LTV-MPC to ensure the vehicle stability, based on which, a relaxation factor is designed to reduce the energy consumption due to the excessive direct-yaw-moment control inputs. The simulation and hardware-in-the-loop (HIL) test results show that the proposed control framework can effectively reduce the energy consumption for DDEVs while ensuring the vehicle handling stability.

Negative dynamics effect of in-wheel switched reluctance motor with inclined airgap eccentricity on handing stability for electric vehicle

This paper focuses on the negative effect of in-wheel switched reluctance motor (SRM) with inclined airgap eccentricity for the handling stability of electric vehicle (EV). Firstly, the radial electromagnetic force of the SRM under inclined airgap eccentricity is deduced based on the Maxwell stress tensor and airgap permeability correction coefficient, and the calculation results are verified by the built measurement device. Then, a dynamics model of in-wheel motor driving EV is constructed according to the response relationship of driving wheels. Finally, the influence of unbalanced radial torque (URT) on the negative dynamic effect of EV is analyzed with angular step input and sine input respectively. The simulation results show that the EV will deviate from the expected trajectory due to the impact of URT, which will threaten driving safety in vehicle steering or overtaking. In addition, the vehicle yaw velocity will deteriorate with the increase of the driving speed and turning angle, which will affect the dynamics response of vehicle handling stability. This research, starting from the coupling relationship between in-wheel motor response characteristics and vehicle driving conditions, can provide theoretical support for the popularization and application for in-wheel motor driving EVs.

Research on the Vehicle Steering and Braking Stability Region

Solving the stability region in the plane motion of vehicles has become a hot research topic in vehicle handling stability under extreme conditions, but there is still a lack of research on the stability region under steering and braking conditions. In this paper, a five-degree-of-freedom (5DOF) nonlinear dynamic model of a vehicle with braking torque introduced is established, and the model is transformed into an equivalent system by using the D’Alembert principle. Then, the equilibrium points of the equivalent system are solved by using an improved hybrid algorithm combining the genetic algorithm (GA) and sequential quadratic programming (SQP) method. According to the bifurcation characteristics of the equilibrium points, the boundary of the stability region at the given initial longitudinal velocity is determined, and the three-dimensional stability region is fitted. Finally, the stability region of the equivalent system and the original system are analyzed by the energy dissipation method, and the stability region determined by the equilibrium point bifurcation method is verified by simulation. The results show that as the braking torque increases, the number of equilibrium points increase to three from one, the equilibrium bifurcation method proposed in this paper can effectively solve the stability region of the equivalent system, and the solution results are consistent with the original system stability region. When the limited braking torque is 500 N·m and the initial longitudinal velocity increases from 30 m/s to 50 m/s, the absolute value of the front wheel steering angle at the boundary point changes from less than 0.02 rad to more than 0.02 rad.

Study of the influence of universal gearing of steering system on vehicle handling stability.

The handling stability of a vehicle is a crucial performance aspect. In this study, the focus is on investigating the impact of the universal gearing of the steering shaft on the handling stability of the vehicle. The research involves a theoretical analysis of how the structural parameters of universal gearing affect the handling stability of the vehicle, which is then validated through a series of simulation experiments including swept-sine steering input simulation, constant radius cornering simulation, and cornering with steer release. Evaluation is based on objective indices such as the steering wheel angle, yaw rate, and lateral acceleration. Moreover, the trends of these indices with respect to the phase angle and initial angle of universal gearing are determined. The findings reveal that the steering ratio of the vehicle varies significantly for varying phase angle and initial angle, resulting in different handling performance. The relationship between the phase angle and fluctuation magnitude of steering ratio is particularly noteworthy, while the impact of initial angle is primarily on the phase of steering ratio. Furthermore, within a certain range, changing the structural parameters of the universal gearing has the potential to enhance the handling performance of the vehicle.