High speed movement control making use of zero dynamics on inverted pendulums

This paper introduces a high-speed motion control technique for inverted pendulums using zero dynamics. Inverted pendulums are self-regulated systems that simulate the motion of a child swinging up an umbrella or stick. The controller design for various pendulums has been widely challenged since the 1970s. Recently, machines using this principle are developed for human riding. Many bipedal robots are also base on this principle. Several researchers have contributed toward the advancement of nonlinear control techniques. However, such inverted pendulums are controlled to avoid falling over. However, this paper presents a contradicting theory. The pendulum deliberately breaks down the balance while in motion. This concept is similar to "sprinting" by speed skaters. Moreover, when the pendulum stops, it restores the balance again. Thus, the controller connected to the movement control mode is designed using partial feedback linearization. Furthermore, when the controller makes the pendulum stop, the control law switches from movement control mode to stationary control mode, which uses linear LQ servo control. The experimental results successfully showed that the pendulum could traverse a distance of 250mm in 0.5-1.0s.