Finite time tracking control for rigid robotic manipulators with friction and external disturbances

The finite time tracking problem is considered for robotic manipulators with unknown dynamic friction, bounded disturbances and unmodeled dynamics. A global relay switching control scheme with finite time convergence is proposed. For general finite time variable structure controller, the control signals may escape to infinity in finite time when the initial states of the system are in some specified area, causing the singularity phenomena of the closed-loop system. The design scheme for finite time tracking control uses a two-phase switching control method so that the boundedness of the control signal is guaranteed and the singularity phenomena is avoided.