Work machine and method for controlling work machine

Abstract

A controller acquires vehicle body posture data. The controller acquires work implement posture data. The controller calculates a height of a work implement in a gravity direction from a reference point of a vehicle body based on the vehicle body posture data and the work implement posture data. The controller controls an actuator so that the height of the work implement in the gravity direction is maintained even when a posture of the vehicle body changes.

1 . A work machine comprising:
 a vehicle body;   a work implement supported so as to be movable with respect to the vehicle body;   an actuator connected to the work implement, the actuator being configured to cause the work implement to move;   a vehicle body sensor configured to detect vehicle body posture data indicative of a posture of the vehicle body;   a work implement sensor configured to detect work implement posture data indicative of a posture of the work implement; and   a controller configured to
 acquire the vehicle body posture data, 
 acquire the work implement posture data, 
 calculate a height of the work implement in a gravity direction from a reference point of the vehicle body based on the vehicle body posture data and the work implement posture data, and 
 control the actuator so that the height of the work implement in the gravity direction is maintained even when the posture of the vehicle body changes. 
   
     
     
         2 . The work machine according to  claim 1 , wherein
 the vehicle body includes
 a front wheel, 
 a vehicle body frame that supports the front wheel and the work implement, 
 a rear wheel, and 
 a tandem drive that supports the rear wheel, the tandem drive includes a rear axis extending in a left-right direction, and the tandem drive supports the vehicle body frame so that the vehicle body frame is swingable about the rear axis, and 
   the controller is configured to maintain the height of the work implement in the gravity direction even when the vehicle body frame swings about the rear axis with respect to the tandem drive.   
     
     
         3 . The work machine according to  claim 2 , wherein
 the reference point of the vehicle body is disposed on the tandem drive.   
     
     
         4 . The work machine according to  claim 1 , further comprising:
 an operating device configured to be operated by an operator,   the controller being configured to
 acquire an operation signal indicative of an operation of the operating device, 
 control the actuator so that the work implement moves according to the operation of the operating device, 
 store, as a target height, a height of the work implement when the operation of the operating device is finished, and 
 control the actuator so that the height of the work implement in the gravity direction is maintained at the target height even when the posture of the vehicle body changes. 
   
     
     
         5 . The work machine according to  claim 1 , wherein
 the controller is configured to control the actuator so that a position of the work implement in the left-right direction is maintained even when the posture of the vehicle body changes.   
     
     
         6 . A method for controlling a work machine that includes a vehicle body, a work implement supported so as to be movable with respect to the vehicle body, and an actuator connected to the work implement and configured to cause the work implement to move, the method comprising:
 acquiring vehicle body posture data indicative of a posture of the vehicle body;   acquiring work implement posture data indicative a posture of the work implement;   calculating a height of the work implement in a gravity direction from a reference point of the vehicle body based on the vehicle body posture data and the work implement posture data; and   controlling the actuator so that the height of the work implement in the gravity direction is maintained, even when the posture of the vehicle body changes.   
     
     
         7 . The method according to  claim 6 , wherein
 the vehicle body includes
 a front wheel, 
 a vehicle body frame that supports the front wheel and the work implement, 
 a rear wheel, and 
 a tandem drive that supports the rear wheel, the tandem drive includes a rear axis extending in a left-right direction, and the tandem drive supports the vehicle body frame so that the vehicle body frame is swingable about the rear axis, and 
   the height of the work implement in the gravity direction is maintained even when the vehicle body frame swings about the rear axis with respect to the tandem drive.   
     
     
         8 . The method according to  claim 7 , wherein
 the reference point of the vehicle body is disposed on the tandem drive.   
     
     
         9 . The method according to  claim 6 , further comprising:
 acquiring an operation signal indicative of an operation of the operating device configured to be operated by an operator;   controlling the actuator so that the work implement moves according to the operation of the operating device;   storing, as a target height, the height of the work implement when the operation of the operating device is finished; and   controlling the actuator so that the height of the work implement in the gravity direction is maintained at the target height even when the posture of the vehicle body changes.   
     
     
         10 . The method according to  claim 6 , further comprising:
 controlling the actuator so that a position of the work implement in the left-right direction is maintained even when the posture of the vehicle body changes.