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Relocating the electric motor to a position inside the wheel offers a variety of benefits, such as reduced overall vehicle weight, more efficient production of vehicles, more flexible design and better road handling because of the accurate torque control on each wheel. However, the motor also increases the unsprung mass, which can impair the ride comfort of the vehicle. In this paper, we propose and investigate a control strategy using the vertical component of the driving force provided by an in-wheel motor for better ride comfort and handling dynamics. In the next stage, a mathematical model of the vehicle with coupled longitudinal, lateral, and vertical dynamics was introduced. The parameters of the vehicle were measured and collected from an actual car equipped with in-wheel motors. To analyze the performance of the controller, a model of the vehicle was tested in a series of simulations. The straight-line acceleration test indicated an improvement to the ride comfort of 31.8% in terms of the RMS vertical vibrations of the sprung mass. The control is achieved without any deterioration of the tire load and the vehicle's longitudinal dynamics. The stable lateral dynamics of the controlled vehicle was confirmed using a sine-sweep steering excitation, conducted on a perfectly smooth road surface with a constant longitudinal acceleration. [ABSTRACT FROM AUTHOR]

Roll and lateral dynamics of a vehicle are heavily coupled together, the increase of roll stability does not necessarily result in the improvement of stability in the lateral plane, but the decrease in lateral stability possibly contributes to instability in the roll plane. To address this challenge, a comprehensive tune of coupled roll and lateral dynamics for a vehicle fitted with hydraulically interconnected suspension system is presented in this paper. A typical sport utility vehicle is selected and modeled with 10 degrees of freedom to conduct the dynamic simulation. Also, the fluid equations of the proposed hydraulically interconnected suspension system with nonlinear damper model are derived and incorporated into the vehicle model. Furthermore, the integrated model is validated by the field test. The simulation is also conducted to assess and compare the vehicle roll and lateral dynamic performances under fishhook maneuver. The results show that the well-tuned hydraulically interconnected suspension can suppress its body motion in roll plane, enhance the yaw rate tracking ability, minimize the sideslip angle at the center of gravity, and also decrease the slip angles for tires. Last, the parameter sensitivity analysis for a strongly nonlinear hydraulically interconnected suspension system illustrates how individual hydraulically interconnected suspension parameters (roll stiffness, roll stiffness nonlinearity, roll stiffness distribution ratio, and damping ratio) contribute to different dynamic aspects of a vehicle. The results indicate that, by controlling hydraulically interconnected suspension key parameters, the vehicle dynamic performance can be effectively controlled in both roll and lateral planes. The parameter sensitivity analysis findings have pointed out the direction for controller design and laid the foundation for active hydraulically interconnected suspension system development in the future. [ABSTRACT FROM AUTHOR]

In this study, a nonlinear predictive control method is developed for the active steering control of a sport utility vehicle. The method is tested on a nonlinear mathematical model of an 11-degree-of-freedom vehicle. The system performance is evaluated by considering that the control law must keep the actual yaw rate close to the desired yaw rate and minimizing the vertical load changes at each wheel. The latter is proposed for this work. The vertical load changes play an important role in the dynamics and the stability of the system. The effectiveness of the control method is demonstrated through numerical simulation by using a vehicle model that includes three case studies: rapid lane change at low and high velocities and the fishhook manoeuvre. The results show that the stability of the vehicle is maintained and its rollover propensity is decreased. In addition, the proposed controller is compared with a well-known linear model predictive controller. [ABSTRACT FROM AUTHOR]

Coordination of chassis control systems can contribute to an improved overall performance of a vehicle. In this paper, a novel vehicle stability control scheme is proposed that integrates both the direct yaw moment control and active rear steering. The controller is synthesized via an upper-level control structure and a lower-level control structure. The required yaw moment and rear steering angle are generated using a sliding-mode controller in the upper-level control. The stability of a sliding-mode controller is proved using a Lyapunov function. The yaw moment is subsequently realized by distributing the braking torque between appropriate wheels in the lower-level control using a braking torque distribution scheme. The effectiveness of the proposed controller is demonstrated through open-loop and closed-loop simulations of a non-linear vehicle model, in terms of selected vehicle handling and control performance measures, namely yaw rate and side-slip angle tracking. The results obtained for different manoeuvres suggest that the proposed two-level control scheme can help to achieve substantial enhancements in the handling performance and the stability performance of the vehicle. [ABSTRACT FROM AUTHOR]

In order to improve the handling and stability of a tractor–semitrailer, a new sliding-mode controller is designed on the basis of a non-linear three-degree-of-freedom model of the vehicle. Three state variables, namely the tractor’s yaw rate, the tractor’s lateral velocity and the articulation angle, are controlled as the target responses using active steering. A new version of the desired articulation angle is proposed so that the rear end of the semitrailer unit is forced to follow the path of the fifth wheel if the proposed reference value is tracked. A 12-degree-of-freedom non-linear model of the articulated heavy vehicle validated by real test data is used to evaluate the control system. The comparative simulation results prove the significant effects of the proposed non-linear control method with respect to a previously designed linear controller on improving the handling and stability performance, especially under severe driving conditions. [ABSTRACT FROM AUTHOR]