Work machine and method for automatically controlling the trajectory of an implement relative to a target surface grade

Abstract

A method is described for controlling movement of a ground-engaging tool for a work machine, for example a bucket or blade coupled to the machine frame via a boom assembly, and more particularly a point of interest such as a tool tip. A number of previous and/or future locations are determined for a point of interest associated with the ground-engaging tool, based on sensed point of interest data comprising a current location, a current trajectory, and a current velocity thereof. A convergence trajectory is calculated for the point of interest from the current location and with respect to a target surface profile, based at least in part on the determined previous and/or future locations along the current trajectory. Output signals are generated for automatic control of movement of the point of interest based at least in part on the calculated convergence trajectory.

What is claimed is: 
     
         1 . A computer-implemented method of controlling movement of a ground-engaging tool for a work machine, wherein the ground-engaging tool is at a first end of an implement comprising one or more components coupled on a second end thereof to, and independently moveable with respect to, a main frame of the work machine, the method comprising:
 determining one or more future locations for a point of interest associated with the ground-engaging tool, based on sensed point of interest data comprising a current location, a current trajectory, and a current velocity thereof;   calculating a convergence trajectory for the point of interest from the current location and with respect to a target surface profile, based at least in part on the determined one or more future locations along the current trajectory; and   generating output signals for automatic control of movement of the point of interest based at least in part on the calculated convergence trajectory.   
     
     
         2 . The computer-implemented method of  claim 1 , comprising adjusting one or more characteristics of the calculated trajectory based on one or more predicted slope transitions associated with a plurality of determined future locations. 
     
     
         3 . The computer-implemented method of  claim 2 , wherein the one or more characteristics comprise a magnitude of the trajectory. 
     
     
         4 . The computer-implemented method of  claim 2 , wherein the one or more slope transitions are predicted using calculated surface normal vectors respectively associated with the plurality of determined future locations. 
     
     
         5 . The computer-implemented method of  claim 1 , further comprising determining one or more previous locations of the point of interest, and calculating the convergence trajectory further based at least in part on the determined one or more previous locations. 
     
     
         6 . The computer-implemented method of  claim 5 , comprising adjusting one or more characteristics of the calculated convergence trajectory based on one or more predicted slope transitions associated with a plurality of determined previous and future locations. 
     
     
         7 . The computer-implemented method of  claim 6 , wherein the one or more characteristics comprise a magnitude of the trajectory. 
     
     
         8 . The computer-implemented method of  claim 6 , wherein the one or more slope transitions are predicted using calculated surface normal vectors respectively associated with the plurality of determined previous and future locations. 
     
     
         9 . The computer-implemented method of  claim 1 , comprising:
 mapping a current surface profile and the target surface profile in a three dimensional coordinate framework; and   calculating an error between the current surface profile and the target surface profile with respect to a previously traversed portion by the point of interest.   
     
     
         10 . The computer-implemented method of  claim 9 , comprising generating feedback comprising the calculated error for further calculating the convergence trajectory and/or controlling movement of the point of interest. 
     
     
         11 . A work machine comprising:
 a ground-engaging tool at a first end of an implement comprising one or more components coupled on a second end thereof to, and independently moveable with respect to, a main frame of the work machine; and   one or more processors configured to:
 determine one or more future locations for a point of interest associated with the ground-engaging tool, based on sensed point of interest data comprising a current location, a current trajectory, and a current velocity thereof; 
 calculate a convergence trajectory for the point of interest from the current location and with respect to a target surface profile, based at least in part on the determined one or more future locations along the current trajectory; and 
 generate output signals for automatic control of movement of the point of interest based at least in part on the calculated convergence trajectory. 
   
     
     
         12 . The work machine of  claim 11 , wherein the one or more processors are configured to adjust one or more characteristics of the calculated trajectory based on one or more predicted slope transitions associated with a plurality of determined future locations. 
     
     
         13 . The work machine of  claim 12 , wherein the one or more characteristics comprise a magnitude of the trajectory. 
     
     
         14 . The work machine of  claim 12 , wherein the one or more slope transitions are predicted using calculated surface normal vectors respectively associated with the plurality of determined future locations. 
     
     
         15 . The work machine of  claim 11 , wherein the one or more processors are further configured to determine one or more previous locations of the point of interest, and calculate the convergence trajectory further based at least in part on the determined one or more previous locations. 
     
     
         16 . The work machine of  claim 15 , wherein the one or more processors are further configured to adjust one or more characteristics of the calculated convergence trajectory based on one or more predicted slope transitions associated with a plurality of determined previous and future locations. 
     
     
         17 . The work machine of  claim 16 , wherein the one or more characteristics comprise a magnitude of the trajectory. 
     
     
         18 . The work machine of  claim 16 , wherein the one or more slope transitions are predicted using calculated surface normal vectors respectively associated with the plurality of determined previous and future locations. 
     
     
         19 . The work machine of  claim 11 , wherein the one or more processors are further configured to:
 map a current surface profile and the target surface profile in a three dimensional coordinate framework; and   calculate an error between the current surface profile and the target surface profile with respect to a previously traversed portion by the point of interest.   
     
     
         20 . The work machine of  claim 19 , wherein the one or more processors are further configured to generate feedback comprising the calculated error for further calculating the convergence trajectory and/or controlling movement of the point of interest.