A drilling machine includes a frame, a tower that is supported by the
frame, two tracks for movement over the ground, at least four yokes that
interconnect the frame and the two tracks, a plurality of hydraulic
cylinders, a plurality of sensors, and a controller. The tower includes a
drill string. Each yoke is connected to the frame and one of the tracks.
Each hydraulic cylinder is movable in response to a control signal and
connected to the frame and a yoke. Each sensor senses a parameter
indicative of force and generates an output signal that represents the
force. The controller receives the output signals from the sensors,
determines a center of gravity of the drilling machine, and generates the
control signals for the hydraulic cylinders based on the center of
gravity. Each hydraulic cylinder is controlled to move to maintain the
center of gravity within a boundary area.