Variable structure control is applied to an underactuated two and
three-link robot. Control laws are developed to invert the robot from its
stable, downward equilibrium position to an inverted position. This maneuver is
accomplished by pumping energy into the system with the variable structure
controller. A linear balancing controller is activated once the robot nears the
inverted position. Numerical simulations are presented for both the two and
three-link robot.