Abstract
In this paper, we discuss a stabilization of a parallel-type double inverted pendulum system. First, analysing the derived state space equation of the pendulum system and comparing with other pendulum systems which are sires-type and single-sype, we make qualitative characteristics clear. Especially, we show that there exists some difficulty of stabilization in the parallel-type, caused by the natural frequency ratio of two pendulums. Based on the above results, we synthesize some controllers which are constructed by a state feedback gain and full state observer, and confirm that the pendulum system can be stabilized in both simulation and experiment.