A Class Of Underactuated Mechanical Systems, Motion Control Strategy Study

The control of nonholonomic underactuated systems is an important field in nonlinear control. This paper uses the example of a pendubot to illustrate the control of such systems.To solve the control problems of the pendubot, two control strategies are proposed in this paper.Lagrange dynamics is used to obtain the dynamical equation of pendubot. Energy-based on-line system identification method and CAD model method are used to measure the parameters of the system. Based on the dynamical equation and the parameters of the system, two control strategies of the pendubot are proposed.Pendubot strategy based on partial feedback linearization and LQR has the strongpoints of swinging up quickly and switching smoothly between the controllers. But the parameters of this strategy are difficult to be adjusted suitably and the pendubot is difficult to be controlled successfully.To solve the problems in pendubot strategy based on partial feedback linearization and LQR, another control strategy based on fuzzy control and LQR is proposed. It not only solve the disadvantages of the strategy based on partial feedback linearization and LQR, but also has the strongpoints of swinging up quickly and switching smoothly between the controllers. At the same time, the configuration of swing-up controller is simple.Based on the research of this paper, a control framework of pendubot is established which provides new method of controlling nonholonomic underactuated systems.