Movement control of two-wheeled inverted pendulum robots considering robustness

We propose a high-speed robust motion control technique for inverted pendulum robots that utilizes forward and backward tilting as a control factor. An inverted pendulum is a self-regulated system simulating a child's game of swaying an umbrella or a stick upwards. The controller design for pendulums has been widely been challenged since the 1970s. A two-wheeled, self-balancing electric transportation device using the inverted pendulum's control principle was developed in the US. Many biped walking robots have also made use of this principle. Furthermore, the feature of space-saving of inverted pendulum robots will be highly regarded and they will contribute to our better lives. On the other hand, essentially, inverted pendulums possess better control characteristics since they do not fold up. Shimada and Hatakeyama suggested an idea that was contrary to this basic principle. Their controller was designed to brake down its balance when in motion. This was done using zero dynamics derived by partial feedback linearization, in order to control revolving and curving motion. However, this control system is a feedfoward control making use of forward and backward tilting and it is not robust. To solve this problem, we have designed a two degrees of freedom controller based on the feedfoward controller and H_∞ control technique. Finaly we present the simulation and experimental results for validity.