Analytical modeling, analysis and robust control of uncertain nonlinear dynamical systems by using sliding mode control (SMC) and quantitative feedback theory (QFT)

This dissertation consists of three sections. One of the main goals in this dissertation is to apply a robust control method to design a driver seat of a heavy vehicle to reduce driver fatigue. In the first section (Chapter 2), some of the important nonlinear suspension effects that may help to improve the directional stability of trucks are investigated. A six-degree-of-freedom nonlinear suspension roll model of a heavy truck axle unit is presented. This model includes the effects of nonlinear tire damping, road inclination angle, and variation of suspension angles.; In the second section (Chapter 3), the driver seat vibration, which can lead to driver fatigue, of a heavy truck model is presented in a nonlinear framework. The model consists of a sprung mass, an unsprung mass, and a driver seat. All springs and dampers are considered nonlinear. An external force as a sudden impact on any of the truck-trailer wheels is used to analyze the vibrations of the seat to obtain information on the driver fatigue. The dynamic behavior of the driver seat including the unsprung and sprung masses is illustrated using parameters dependent phase portraits.; A robust control method, combining Sliding Mode Control (SMC) and Quantitative Feedback Theory (QFT), for designing a driver seat of a heavy vehicle to reduce driver fatigue is given in the third section (Chapter 4 and Chapter 5). In addition, this nonlinear mathematical modeling technique is applied to an inverted pendulum (IP) in Chapter 4. These mathematical models are used to analyze the tracking control characteristics, through computer simulations, to demonstrate the effectiveness of the proposed control methodology. Furthermore, three-degree-of-freedom inverted pendulum model is used to experimentally validate the theoretical model and simulations.; In Chapter 5, the SMC is used to track the trajectory of the desired motion behavior of the seat. However, when the system enters into sliding regime, chattering occurs due to switching delays as well as sprung mass vibrations. The chattering is eliminated with the introduction of QFT inside the boundary layer to ensure smooth tracking. Furthermore, this dissertation also partially fulfills the lack of existing nonlinear models for turning trucks.