| Summary: | 博士 === 國立交通大學 === 電機與控制工程系所 === 95 === In this dissertation, issues of stabilization designs and path-following design for vehicle's lateral dynamics are presented. In the recent years, the study of intelligent transportation systems has attracted considerable attention, especially the steering control of vehicle under cruise control mode. Based on the assumption of constant driving speed, a second-order nonlinear lateral dynamical model is obtained. It is observed that saddle-node bifurcation will appear in vehicle dynamics with respect to the variation of the front wheel steering angle, which might result in spin and/or system instability. In order to possibly prevent the occurrence of such an instability, we propose linear and nonlinear stabilization designs for vehicle system. The controllability of this vehicle dynamics at the saddle-node bifurcation point is first discussed. This leads to the design of a state feedback control law for system stabilization. To enhance the performance of linear control design, nonlinear control schemes for vehicle's lateral dynamics are discussed. The vehicle dynamics at the saddle-node bifurcation point is decomposed as an affine nominal model plus the remaining term of the overall system dynamics. Feedback linearization scheme is then employed to construct the stabilizing control law for the nominal model. To cover the remaining term of system dynamics, Lyapunov redesign is adopted and added to feedback linearization scheme. After that, sliding mode control method is applied to design the robust control law for vehicle dynamics. The stability of the overall vehicle dynamics at the saddle-node bifurcation point is guaranteed by applying Lyapunov stability criteria. Parametric analysis of system equilibrium for an example vehicle model with proposed control designs is also obtained to classify the regime of control gains for potential behavior of vehicle's dynamical behavior. In addition to stabilization designs for vehicle's lateral dynamics, we also design the path-following control law for vehicle system by applying sliding mode control method. Numerical simulations for an example model demonstrate the effectiveness of analytical results.
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