Unified control for Pendubot at four equilibrium points

The authors consider the control of an underactuated mechanical system: Pendubot, which has four separated equilibrium points. A unified controller is proposed to stabilise the system at the four equilibrium points. Moreover, the proposed unified control can bring the underactuated link to ideal homoclinic orbits, which cannot be achieved by existing approaches. Simulation results verify the effectiveness of the proposed control.