Graduate School of Science, Okayama University of Science
Abstract
It is the purpose of this paper to design and realize the digital control system which can stabilize a double inverted penpulum in order to use a penumatic motor as an actuater instead of an electric motor in the next step of this study. A double inverted pendulum is a typical unstable mechanical system and is much more difficult to be controlled than a single inverted pendulum. The system consists of a double pendulum, a cart, electric motor and a personal computer PC-9801VX. The results obtained can be summarized as follows : 1) By inserting a model compensator between a servo amplifier and a D/A converter, the nonlineality due to the saturation of an amplifier can be reduced and a double inverted pendulum can be stabilized. Such a compensator is very useful to design a control system by using a high response motor with the servo amplifier because a linear control theory can be applied easily. 2) When a cart speed and angular velocities of pendulum are estimated by differentiating the displacement and angles respectively, a double pendulum can be kept stand invertedly even though a cart rattles because of a low resolution encoder. 3) When an optimal observer is added to the control system, a double inverted pendulum can not be stabilized for a long time, but a cart can move smoothly. This is caused by mainly the coulomb friction which exists in the shaft of the upper pendulum
