Work machine and method for controlling work machine

Abstract

A work machine includes a vehicle body, a blade supported so as to be rotatable about a pitch axis with respect to the vehicle body, a pitch actuator connected to the blade, a first sensor, and a controller. The pitch actuator causes the blade to perform a pitch motion about the pitch axis in a forward tilt direction and a backward tilt direction. The first sensor detects a first parameter relating to a penetration force of a blade tip of the blade in a downward direction. The controller determines whether the penetration force is insufficient based on the first parameter, and controls the pitch actuator to cause the blade to perform the pitch motion in the forward tilt direction upon determining that the penetration force is insufficient.

1 . A work machine comprising:
 a vehicle body;   a blade supported so as to be rotatable about a pitch axis with respect to the vehicle body;   a pitch actuator connected to the blade, the pitch actuator being configured to cause the blade to perform a pitch motion about the pitch axis in a forward tilt direction and a backward tilt direction;   a first sensor configured to detect a first parameter relating to a penetration force of a blade tip of the blade in a downward direction; and   a controller configured to
 determine whether the penetration force is insufficient based on the first parameter, and 
 control the pitch actuator to cause the blade to perform the pitch motion in the forward tilt direction upon determining that the penetration force is insufficient. 
   
     
     
         2 . The work machine according to  claim 1 , further comprising:
 a lift frame supported so as to be rotatable about a lift axis with respect to the vehicle body; and   a lift actuator connected to the lift frame and the vehicle body, the lift actuator being configured to cause the lift frame to perform a lift motion up and down about the lift axis,
 the lift actuator being a hydraulic cylinder, and 
 the first parameter being a bottom pressure of the lift actuator. 
   
     
     
         3 . The work machine according to  claim 2 , wherein
 the controller is configured to increase a pitch angle of the blade in the forward tilt direction according to an increase of the first parameter when the first parameter is greater than or equal to a first threshold.   
     
     
         4 . The work machine according to  claim 1 , wherein
 the vehicle body includes
 a front wheel, 
 a rear wheel, and 
 a crawler belt wound around the front wheel and the rear wheel, and 
   the first threshold is determined based on the penetration force when the front wheel is lifted up.   
     
     
         5 . The work machine according to  claim 1 , wherein
 the controller is configured to
 determine a digging state of the work machine, and 
 cause the blade to perform the pitch motion in the forward tilt direction according to the digging state. 
   
     
     
         6 . The work machine according to  claim 5 , further comprising:
 a second sensor configured to detect a second parameter relating to a load applied to the blade tip of the blade in a horizontal direction,   the controller being configured to determine the digging state based on the second parameter.   
     
     
         7 . The work machine according to  claim 6 , wherein
 the pitch actuator is a hydraulic cylinder, and   the second parameter is a head pressure of the pitch actuator.   
     
     
         8 . A method for controlling a work machine including a vehicle body, a blade supported so as to be rotatable about a pitch axis with respect to the vehicle body, and a pitch actuator connected to the blade, the pitch actuator being configured to cause the blade to perform a pitch motion about the pitch axis in a forward tilt direction and a backward tilt direction, the method for controlling the work machine comprising:
 detecting a first parameter relating to a penetration force of a blade tip of the blade in a downward direction;   determining whether the penetration force is insufficient based on the first parameter; and   controlling the pitch actuator to cause the blade to perform the pitch motion in the forward tilt direction upon determining that the penetration force is insufficient.   
     
     
         9 . The method according to  claim 8 , wherein
 the work machine further includes a lift frame supported so as to be rotatable about a lift axis with respect to the vehicle body, and a lift actuator connected to the lift frame and the vehicle body,   the lift actuator is configured to cause the lift frame to perform a lift motion up and down about the lift axis,   the lift actuator is a hydraulic cylinder, and   the first parameter is a bottom pressure of the lift actuator.   
     
     
         10 . The method according to  claim 9 , further comprising:
 increasing a pitch angle of the blade in the forward tilt direction according to an increase of the first parameter when the first parameter is greater than or equal to a first threshold.   
     
     
         11 . The method according to  claim 8 , wherein
 the vehicle body includes a front wheel, a rear wheel, and a crawler belt wound around the front wheel and the rear wheel, and   the first threshold is determined based on the penetration force when the front wheel is lifted up.   
     
     
         12 . The method according to  claim 8 , further comprising:
 determining a digging state of the work machine; and   causing the blade to perform the pitch motion in the forward tilt direction according to the digging state.   
     
     
         13 . The method according to  claim 12 , further comprising:
 detecting a second parameter relating to a load applied to the blade tip of the blade in a horizontal direction,   the determining the digging state being based on the second parameter.   
     
     
         14 . The method according to  claim 13 , wherein
 the pitch actuator is a hydraulic cylinder, and   the second parameter is a head pressure of the pitch actuator.