Patent ID: 8437925

Claim:
A leveling control method for heavy construction equipment in which a lower frame and an upper frame, the lower frame having traveling means, the upper frame tiltably and swingably connected to the lower frame by tilting means that includes a sensor unit, a control unit, and a driving unit, the method comprising the steps of: (A) the sensor unit sensing twist angles of the lower frame and the upper frame against a reference horizontal surface as inclination sensors of the lower frame and the upper frame, measuring a traveling speed of the heavy equipment as a traveling sensor, and detecting working state information of working devices; (B) the control unit calculating a correction angle, at which the upper frame is to be tilted, based on the twist angles in an auto leveling mode, a re-leveling mode, or a track leveling mode, generating an actuator control signal for performing a leveling control of the upper frame in accordance with the correction angle, and transmitting the control signal to the driving unit; and (C) the driving unit performing the leveling control by operating actuators based on the control signal; wherein the step (B) in the auto leveling mode comprises the steps of: (b 11 ) judging whether conditions precedent to control are satisfied, and if the conditions precedent to control are not satisfied, terminating the leveling control; (b 12 ) if the conditions precedent to control are satisfied, setting the twist angle of an upper swing structure as a first twist angle, and calculating the correction angle for tilting the upper swing structure from the first twist angle; (b 13 ) if the correction angle is 0°, returning to the step (b 12 ), while if the correction angle is not 0°, calculating a second twist angle (i.e. a twist angle of the upper swing structure against the lower frame), and if the second twist angle is out of the maximum allowable twist angle range (i.e. the minimum to maximum value range of the second twist angle), terminating the tilting control; (b 14 ) if the second twist angle is within the maximum allowable twist angle range, generating a control signal for instructing an operation of the actuators in accordance with the correction angle and the second twist angle, and transmitting the control signal to the driving unit; (b 15 ) if the equipment is in a traveling state after the step (b 14 ) returning to the step (b 12 ); (b 16 ) if the equipment is not in a traveling state in step (b 15 ), starting counting of the operation time; (b 17 ) performing the steps (b 12 ) to (b 15 ) after the step (b 16 ), if the correction angle is 0° in step (b 13 ), terminating the tilting control, and if the equipment is in a traveling state after the step (b 15 ), returning to the step (b 12 ); and (b 18 ) if the equipment is not in a traveling state in step (b 17 ) and the operation time is more than the predetermined reference operation time, terminating the tilting control, while if the operation time is less than the reference operational time, returning to the step (b 17 ).