In this paper, an optimal controller for integrated longitudinal and lateral closed loop vehicle/driver dynamics proposed to follow desired path in various driving maneuvers, which also improved maneuverability and stability of vehicle over desired path. Designed controller imposed corrected steering angle and torque on the wheels to keep the vehicle on the desired trajectory whilst modified its handling properties. In the next stage, performance of proposed optimal linear quadratic regulator (LQR) controller compared with Proportional-integrated-derivative (PID) one. The proposed controllers has been implemented on vehicle eight degree of freedom model in MATLAB/Simulink. Then the effects of adaptive controller on vehicle path following has been examined for various maneuvers, by driving on the lane change, J-turn, double lane-change and desired tracks. Finally, longitudinal dynamic performance of vehicle has been investigated during severe braking conditions. Simulation results indicated the dominate efficiency of controller on the vehicle stabilization and path following. Also, it improved longitudinal dynamics performance by preventing wheel lock and reducing stopping distance.

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PurposeIn actual application of a DC-DC boost converter, the input voltage and resistive load may be changed frequently, and these variations deteriorate the conventional controller performance. The purpose of this paper is to present an observer-based control scheme for a DC-DC boost converter with an unknown resistive load and input voltage. Design/methodology/approachTo estimate the unknown input voltage and resistive load, a nonlinear observer is designed by using the Lyapunov stability theorem. In addition, the closed-loop stability of the proposed control scheme for the DC-DC boost converter is proven. To convert the continuous control input to discrete mode, a sigma–delta modulator is used. FindingsThe proposed control scheme is validated in different situations. The adaptive structure of the proposed control scheme is tested by the input voltage, load and reference signal variation, and the simulation results confirm the capability of the proposed observer-based control strategy. Originality/valueThe contribution of this paper is twofold: according to nonlinear controller design, the feedforward term of the nonlinear controller is obtained via the observer, and unlike the proportional–integral controller, performance deterioration in the input voltage and load variations are unraveled. The effectiveness of this method is validated by experimental implementation in the presence of load and input voltage variations, and the experimental results confirm the efficacy of the proposed strategy.

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This paper addresses the problem of state and parameter estimation for a class of uncertain DC-DC such converters as DC–DC boost, buck and buck-boost converters. Using the advantages of Immersion and Invariance technique with input-output filtered transformation, a proper immersion and auxiliary dynamic filter is constructed in the proposed estimator. Uniform global asymptotic convergence of the estimator is proven for the system with parametric uncertainties. In the presence of both output and state dynamics perturbations, the performance of the proposed estimator has been theoretically analyzed and verified by means of simulation results. In addition, the effectiveness of this scheme is validated via experimental test for DC-DC boost converter.