Blade control device for work machine

Abstract

In a blade control device, in a case where an update condition set in advance is satisfied, a virtual design surface setting part sets a virtual design surface, using a blade position when the update condition is satisfied as a reference, at an angle equivalent to a vehicle body angle, and a blade operation control part restricts raising and lowering operation of a blade such that the blade conducts the raising and lowering operation above the virtual design surface.

1 . A blade control device which is provided in a work machine including a machine body having a travelling device and a vehicle body supported by the travelling device and a blade attached to the machine body so as to be raised and lowered and which controls raising and lowering operation of the blade, the blade control device comprising:
 a target design surface setting part which sets a target design surface that specifies a target shape of an object to be dug by the blade;   a position information acquiring part which acquires position information related to the work machine;   a blade position calculating part which calculates a blade position as a position of the blade on the basis of the position information acquired by the position information acquiring part;   a virtual design surface setting part which sets a virtual design surface above the target design surface; and   a blade operation control part which controls the raising and lowering operation of the blade,   wherein   in a case where an update condition set in advance is satisfied, the virtual design surface setting part sets the virtual design surface, using the blade position when the update condition is satisfied as a reference, at an angle equivalent to a vehicle body angle as an angle of inclination of the vehicle body with respect to a horizontal surface, the angle of inclination being obtained on the basis of the position information, and   the blade operation control part restricts the raising and lowering operation of the blade such that the blade conducts the raising and lowering operation above the virtual design surface.   
     
     
         2 . The blade control device according to  claim 1 , further comprising
 an estimated position calculating part which calculates an estimated position of a part of a present surface which is the ground as the object to be dug, the part being associated with at least one of the blade and the travelling device, on the basis of the position information acquired by the position information acquiring part,   wherein the update condition includes a condition that the estimated position is below the virtual design surface.   
     
     
         3 . The blade control device according to  claim 1 , wherein
 the update condition includes a condition corresponding to non-setting of the virtual design surface.   
     
     
         4 . The blade control device according to  claim 1 , further comprising:
 a blade load acquiring part which acquires a blade load as a load applied to the blade; and   a storage part which stores a load threshold value as a threshold value of the blade load,   wherein   the update condition includes a condition that the blade load changes from a value equal to or greater than the load threshold value to a value smaller than the load threshold value.   
     
     
         5 . The blade control device according to  claim 1 , further comprising
 a vehicle body average angle calculating part which calculates an average value of vehicle body angles acquired by the position information acquiring part,   wherein the virtual design surface setting part uses the average value of the vehicle body angles as the vehicle body angle to be a reference for setting the virtual design surface.