Complex Geometry Pavement Milling

Abstract

Disclosed is a method and apparatus for digital control of a milling machine drum to minimize road material milled using complex geometry. A digital representation of a surface and/or subsurface of a road is loaded into a controller. Road defects are identified based on the digital surface, by comparing defect digital characteristics with the digital surface. A minimum removal map can be generated using the defect digital characteristics. A milling tool path can then be generated to minimize material removal, based on the minimum removal map. The mill depth and movement of a mill drum can then be controlled based on the milling tool path.

What is claimed is: 
     
         1 . A method for digital control of a mill drum of a milling machine to minimize milled road material during pavement repair, the method comprising:
 loading a digital surface of the road into a controller;   analyzing the digital surface by the controller to identify road defects comprising road surface defects and/or subsurface defects;   generating a minimum removal map comprising one or more removal volumes, based at least in part upon defect digital characteristics;   generating a milling tool path based on the minimum removal map and a mill cutting profile, for removal of the one or more removal volumes; and   controlling a milling depth and movement of a mill drum based on the milling tool path.   
     
     
         2 . The method of  claim 1 , wherein generating a minimum removal map comprises determining a minimum material removal volume for a road defect based at least in part upon a minimum horizontal clearance from a defect boundary, and a minimum vertical clearance from the defect boundary. 
     
     
         3 . The method of  claim 2 , wherein generating a minimum removal map further comprises combining said minimum material removal volume for each of a plurality of road defects. 
     
     
         4 . The method of  claim 3 , wherein controlling a milling depth and movement of a mill drum based on the minimum removal map comprises using the mill drum to remove at least the minimum material removal volume. 
     
     
         5 . The method of  claim 2 , wherein generating a minimum removal map comprises:
 calculating a horizontal defect boundary by vertically projecting the road defect to a virtual calculation plane.   
     
     
         6 . The method of  claim 5 , wherein the virtual calculation plane is a horizontal plane. 
     
     
         7 . The method of  claim 6 , wherein the virtual calculation plane is aligned with an average height of a road surface. 
     
     
         8 . The method of  claim 5 , wherein calculating a horizontal defect boundary further comprises defining a loop enclosing the road defect. 
     
     
         9 . The method of  claim 5 , wherein generating a minimum removal map further comprises identifying an expanded horizontal defect boundary by expanding the horizontal defect boundary outward by a minimum horizontal clearance. 
     
     
         10 . The method of  claim 9 , wherein generating a minimum removal map further comprises sweeping the expanded horizontal defect boundary vertically to create a removal volume associated with the road defect. 
     
     
         11 . The method of  claim 1 , wherein:
 analyzing the road surface to identify road defects comprises comparing the digital surface with defect digital characteristics within a digital library of defect digital characteristics to a type associated with the road defect; and   the removal volumes are determined based at least in part upon the road defect type.   
     
     
         12 . The method of  claim 1 , wherein analyzing the digital surface of the road to identify road defects comprises feeding the digital surface to a trained machine learning model. 
     
     
         13 . The method of  claim 1 , wherein generating a minimum removal map comprises:
 identifying, within the digital surface, a road defect center point; and   defining an enclosed loop for the road defect by connecting points measured radially from the road defect center point to an outermost defect edge.   
     
     
         14 . The method of  claim 13 , wherein the points measured radially from the road defect center point to an outermost defect edge are measured in radial increments of  3  degrees or less, measured on a virtual calculation plane. 
     
     
         15 . The method of  claim 10 , wherein sweeping the expanded horizontal defect boundary vertically comprises sweeping the expanded horizontal defect boundary to a predetermined depth. 
     
     
         16 . The method of  claim 10 , wherein sweeping the expanded horizontal defect boundary vertically comprises sweeping the expanded horizontal defect boundary to a depth based at least in part upon a detected depth of a subsurface defect. 
     
     
         17 . The method of  claim 1 , wherein generating a milling tool path further comprises generating a milling tool path to minimize removal of material outside the minimum removal map and minimize mill vertical movement. 
     
     
         18 . The method of  claim 1 , wherein the mill drum is configured for lateral movement, and wherein generating a milling tool path further comprises generating a milling tool path configured to minimize lateral translation of the mill drum. 
     
     
         19 . The method of  claim 1 , wherein:
 the milling machine comprises multiple mill drums; and   portions of the milling tool path are followed by each of the multiple mill drums.   
     
     
         20 . The method of  claim 1 , wherein loading a digital surface of the road into a controller comprises capturing the digital surface of the road via one or more sensors installed on the milling machine. 
     
     
         21 . The method of  claim 20 , wherein capturing the digital surface of the road via one or more sensors installed on the milling machine is performed continuously as the milling machine moves in a direction of travel while milling. 
     
     
         22 . The method of  claim 1 , further comprising a preceding step of capturing the digital surface of the road via a sensor machine separate from the milling machine; and loading a digital surface of the road into a controller comprises transmitting data corresponding to the digital surface of the road to the milling machine.