Stability of the Controlled Inverted Pendulum With Vertical Oscillations
These days, inverted pendulum robots, like a two-wheeled robot or vehicle, are seen as a form of dynamically stabilized vehicle. Stability characteristics and moving performances of these vehicles have been studied through many examinations and demonstrations. Considering their practical usage, however, these vehicles travel on rough roads, as well as the flat surface in a laboratory. Therefore it is important to investigate the stability of the dynamically stabilized vehicle under vertical vibration. In this study, the authors investigate the responses of the inverted pendulum, which is stabilized by an optimal controller, to vertical vibrations. With theoretical analysis, numerical simulations and experiments using a large scale vibration exciter, stability to vertical vibration is examined. The results show the system dynamics are governed by the Mathieu equation, thus the amplitude ratio reaches its peak when the frequency of the forced vibration is twice the natural frequency of the controlled inverted pendulum system.