Swing Up Control of the Pendubot Through Energy Management of the Underactuated Link

The control problem of the pendubot refers to the task of stabilizing its equilibrium configuration with the highest potential energy. Linearization of the dynamics of the pendubot about this equilibrium results in a completely controllable system and allows a linear controller to be designed for local asymptotic stability. Therefore, the real challenge is to design a control law for the underactuated system that will swing up both the links and brings the configuration variables of the system within the region of attraction of the equilibrium. This paper provides a method for swing-up control based on a series of start and stop maneuvers of the first link about its vertically upright configuration. The start and stop maneuvers are designed such that each maneuver results in a net gain in the energy of the second link. This results in swinging up of the second link and the pendubot configuration reaching the region of attraction of the desired equilibrium. A three step algorithm is provided for swing up control followed by stabilization. Simulation results are presented to demonstrate the efficacy of the approach.Copyright © 2007 by ASME