Swing up control of the Acrobot

Investigates the problem of swing up control of the Acrobot, a two-link, underactuated robot that is a useful vehicle to study problems in nonlinear control. The author develops a swing up strategy based on partial feedback linearization. The algorithm works by creating “unstable zero dynamics” which drives the first link of the Acrobot away from its open loop stable equilibrium toward the inverted position. Control is switched to a linear controller, designed to balance the arm about the inverted configuration, whenever the swing up controller moves the Acrobot into the near vertical position. Simulation results are presented showing the performance of the system