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In this paper, an adaptive sliding mode controller is proposed to improve the vehicle yaw stability and enhance the lateral motion by direct yaw moment control method using active braking systems. As the longitudinal and lateral velocities of the vehicles as well as many other vehicle dynamics variables cannot be measured in a cost-efficient way, a robust control method combined with a state estimator is required to guarantee the system stability. Furthermore, some parameters such as the tyre–road friction coefficient undergo frequent changes, and the aerodynamics resistance forces are often exerted as a disturbance during the wide driving condition. So, an adaptive sliding mode controller is applied to make vehicle yaw rate to track its reference with robustness against model uncertainties and disturbances and a non-linear estimator based on unscented Kalman filter is used to estimate wheel slip, yaw rate, road friction coefficient, longitudinal and lateral velocities. The estimation algorithm directly uses non-linear equations of the system and does not need the linearization and differentiation. The designed controller, which is insensitive to system uncertainties, offers the adaptive sliding gains to eliminate the precise determination of the bounds of uncertainties. The sliding gain values are determined using a simple adaptation algorithm that does not require extensive computational load. Numerical simulations of various manoeuvres using a non-linear full vehicle model with seven degrees of freedom demonstrate the high effectiveness of the presented controller for improving the vehicle yaw stability and handling performance. [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]

The problem of controlling a string of vehicles moving in one dimension is considered so that they all follow a lead vehicle with constant spacing between successive vehicles. Due to practical design and implementation, the negative effect of the tracking lag parameter is taken into account. A hierarchical platoon controller design framework is established comprising a feedback linearization controller at the first layer and a decentralized bidirectional control controller at the second layer. The stability criterion is examined by using a partial differential equation approximation in the limit of the number of vehicles subjected to unequal asymmetry in position and velocity feedback. For disturbance attenuation, string stability analysis is also examined. At the end of the paper, simulations are given to show the efficiency of the proposed results. [ABSTRACT FROM PUBLISHER]