System and method for setting vehicle body coordinate system in work machine

Abstract

A system includes an attitude sensor, a position measurement device, and a controller. The attitude sensor detects an attitude of a first vehicle body. The position measurement device measures a position of a first target part included in a work implement. The controller acquires, from the attitude sensor, the attitude of the first vehicle body while the first body part is stationary with respect to a second vehicle body. The controller sets a vehicle body coordinate system based on the attitude of the first vehicle body and the position of the first target part.

1 . A system for setting a vehicle body coordinate system based on a first vehicle body in a work machine including a second vehicle body, the first vehicle body rotatably connected to the second vehicle body, and a work implement movably attached to the first vehicle body, the system comprising:
 an attitude sensor configured to detect an attitude of the first vehicle body;   a position measurement device configured to measure a position of a first target part included in the work implement; and   a controller configured to
 acquire, from the attitude sensor, the attitude of the first vehicle body while the first vehicle body is stationary with respect to the second vehicle body, and 
 set the vehicle body coordinate system based on the attitude of the first vehicle body and the position of the first target part. 
   
     
     
         2 . The system according to  claim 1 , wherein the controller is configured to
 acquire a plurality of positions of the first target part by causing the work implement to move with respect to the first vehicle body while the first vehicle body is stationary with respect to the second vehicle body, and   set the vehicle body coordinate system based on the attitude of the first vehicle body and the plurality of positions of the first target part.   
     
     
         3 . The system according to  claim 1 , wherein
 the work implement is attached to the first vehicle body to be movable within a work implement plane extending in an up-down direction and a front-back direction of the first vehicle body, and   the controller is configured to
 acquire a plurality of positions of the first target part within the work implement plane by causing the work implement to move while the first vehicle body is stationary with respect to the second vehicle body, 
 calculate normal vector of the work implement plane based on the plurality of positions of the first target part, and 
 determine a direction of a y-axis of the vehicle body coordinate system indicating a left-right direction of the first vehicle body, based on the normal vector of the work implement plane. 
   
     
     
         4 . The system according to  claim 1 , wherein
 the attitude of the first vehicle body includes a pitch angle of the first vehicle body, and   the controller is configured to determine a direction of an x-axis of the vehicle body coordinate system indicating a front-back direction of the first vehicle body, based on the pitch angle of the first vehicle body.   
     
     
         5 . The system according to  claim 1 , wherein
 the work implement is attached to the first vehicle body to be movable within a work implement plane extending in an up-down direction and a front-back direction of the first vehicle body,   the attitude of the first vehicle body includes a pitch angle of the first vehicle body, and   the controller is configured to
 acquire a plurality of positions of the first target part within the work implement plane by causing the work implement to move while the first vehicle body is stationary with respect to the second vehicle body, 
 calculate a normal vector of the work implement plane based on the plurality of positions of the first target part, 
 determine a direction of a y-axis of the vehicle body coordinate system indicating a left-right direction of the first vehicle body, based on the normal vector of the work implement plane, 
 determine a direction of an x-axis of the vehicle body coordinate system indicating a front-back direction of the first vehicle body, based on the pitch angle of the first vehicle body, and 
 determine a direction of a z-axis of the vehicle body coordinate system indicating an up-down direction of the first vehicle body, based on the direction of the y-axis and the direction of the x-axis. 
   
     
     
         6 . The system according to  claim 1 , wherein
 the work machine further includes a positional sensor,   the positional sensor is configured to detect a position of the positional sensor in an external coordinate system based on an outside of the work machine, and   the controller is configured to
 store a machine parameter that defines a positional relationship between the positional sensor and a blade tip of the work implement in the vehicle body coordinate system, and 
 calculate a position of the blade tip in the external coordinate based on the position of the positional sensor in the external coordinate system and the machine parameter. 
   
     
     
         7 . The system according to  claim 6 , wherein
 the controller is configured to
 acquire a target locus of the blade tip for performing predetermined construction work, and 
 control the work implement so that the blade tip moves along the target locus based on the position of the blade tip in the external coordinate system. 
   
     
     
         8 . The system according to  claim 1 , wherein
 the position measurement device is configured to measure a position of a second target part included in the work implement in an external coordinate system based on an outside of the work machine, and   the controller is configured to
 store a machine parameter that defines a dimension of the work implement, and 
 calibrate the machine parameter based on the measured position of the second target part. 
   
     
     
         9 . The system according to  claim 8 , wherein
 the controller is configured to transmit the position of the second target part in the external coordinate system to the position measurement device, and   the position measurement device automatically switches the measurement of a plurality of positions of the second target part based on the position of the second target part received from the controller.   
     
     
         10 . The system according to  claim 8 , wherein
 the work machine further includes a positional sensor,   the positional sensor is configured to detect a position of the positional sensor in the external coordinate system,   the position measurement device is configured to measure a position of a blade tip of the work implement in the external coordinate system and a position of a positional sensor in the external coordinate system, and   the controller is configured to
 generate an external measurement value indicating the position of the blade tip with respect to the positional sensor, based on the measured position of the blade tip and the measured position of the positional sensor, 
 generate an arithmetic value indicating the position of the blade tip with respect to the positional sensor by calculating the position of the blade tip with respect to the positional sensor based on the calibrated machine parameter, and 
 evaluate a precision of the calibration of the machine parameter by comparing the external measurement value and the arithmetic value. 
   
     
     
         11 . A method for setting a vehicle body coordinate system based on a first vehicle body in a work machine including a second vehicle body, the first vehicle body rotatably connected to the second vehicle body, and a work implement movably attached to the first vehicle body, the method comprising:
 acquiring, from an attitude sensor that detects an attitude of the first vehicle body, the attitude of the first vehicle body while the first vehicle body is stationary with respect to the second vehicle body;   measuring a position of a first target part included in the work implement; and   setting the vehicle body coordinate system based on the attitude of the first vehicle body and the position of the first target part.   
     
     
         12 . The method according to  claim 11 , further comprising:
 acquiring a plurality of positions of the first target part by causing the work implement to move with respect to the first vehicle body while the first vehicle body is stationary with respect to the second vehicle body; and   setting the vehicle body coordinate system based on the attitude of the first vehicle body and the plurality of positions of the first target part.   
     
     
         13 . The method according to  claim 11 , wherein
 the work implement is attached to the first vehicle body to be movable within a work implement plane extending in an up-down direction and a front-back direction of the first vehicle body, and the method further comprises:   acquiring a plurality of positions of the first target part within the work implement plane by causing the work implement to move while the first vehicle body is stationary with respect to the second vehicle body;   calculating a normal vector of the work implement plane based on the plurality of positions of the first target part; and   determining a direction of a y-axis of the vehicle body coordinate system indicating a left-right direction of the first vehicle body, based on the normal vector of the work implement plane.   
     
     
         14 . The method according to  claim 11 , wherein
 the attitude of the first vehicle body includes a pitch angle of the first vehicle body, and the method further comprises:   determining a direction of an x-axis of the vehicle body coordinate system indicating a front-back direction of the first vehicle body, based on the pitch angle of the first vehicle body.   
     
     
         15 . The method according to  claim 11 , wherein
 the work implement is attached to the first vehicle body to be movable within a work implement plane extending in an up-down direction and a front-back direction of the first vehicle body,   the attitude of the first vehicle body includes a pitch angle of the first vehicle body, and the method further comprises:   acquiring a plurality of positions of the first target part within the work implement plane by causing the work implement to move while the first vehicle body is stationary with respect to the second vehicle body;   calculating normal vector of the work implement plane based on the plurality of positions of the first target part;   determining a direction of a y-axis of the vehicle body coordinate system indicating a left-right direction of the first vehicle body, based on the normal vector of the work implement plane;   determining a direction of an x-axis of the vehicle body coordinate system indicating a front-back direction of the first vehicle body, based on the pitch angle of the first vehicle body; and   determining a direction of a z-axis of the vehicle body coordinate system indicating an up-down direction of the first vehicle body, based on the direction of the y-axis and the direction of the x-axis.   
     
     
         16 . The method according to  claim 11 , wherein
 the work machine further includes a positional sensor,   the positional sensor is configured to detect a position of the positional sensor in an external coordinate system based on an outside of the work machine, and the method further comprises:   calculating a position of a blade tip in the external coordinate system based on a machine parameter that defines a positional relationship between the positional sensor and the blade tip of the work implement in the vehicle body coordinate system, and the position of the positional sensor in the external coordinate system.   
     
     
         17 . The method according to  claim 16 , further comprising:
 acquiring a target locus of the blade tip for performing predetermined construction work; and   controlling the work implement so that the blade tip moves along the target locus based on the position of the blade tip in the external coordinate system.   
     
     
         18 . The method according to  claim 11 , further comprising:
 acquiring a position of a second target part measured by a position measurement device and included in the work implement in an external coordinate system based on an outside of the work machine; and   calibrating a machine parameter that defines a dimension of the work implement, based on the measured position of the second target part.   
     
     
         19 . The method according to  claim 18 , further comprising:
 transmitting the position of the second target part in the external coordinate system to the position measurement device, and   the position measurement device automatically switching the measurement of a plurality of positions of the second target part based on the position of the second target part received from the controller.   
     
     
         20 . The method according to  claim 18 , wherein
 the work machine further includes a positional sensor,   the positional sensor is configured to detect a position of the positional sensor in the external coordinate system, and the method further comprises:   acquiring a position of a blade tip of the work implement in the external coordinate system and the position of the positional sensor in the external coordinate system, the positions being measured by the position measurement device;   generating an external measurement value indicating a position of the blade tip with respect to the positional sensor, based on the measured position of the blade tip and the measured position of the positional sensor;   generating an arithmetic value indicating the position of the blade tip with respect to the positional sensor by calculating the position of the blade tip with respect to the positional sensor based on the calibrated machine parameter; and   evaluating a precision of the calibration of the machine parameter by comparing the external measurement value and the arithmetic value.