Automated sensor switching

Abstract

A construction machine uses a controller configured to determine a cross-sectional profile of a design surface at a selected position and orientation of a milling drum of the construction machine. The controller automatically determines a preferred sensor sub-set from a plurality of possible sensor sub-sets selected from a set of available sensors. The preferred sensor sub-set must be usable to create at least a portion of the cross-sectional profile of the design surface. The controller automatically maintains or switches control of the milling depth to use the preferred sensor sub-set.

What is claimed is: 
     
         1 . A construction machine, comprising:
 a machine frame having a longitudinal frame axis extending between a front end and a rear end of the machine frame;   a milling drum supported from the machine frame and having a milling drum rotational axis transverse to the longitudinal frame axis;   a set of sensors; and   a controller configured to control a milling depth of the milling drum as the construction machine moves across a ground surface, the controller being configured to:
 access a design surface data set defining a design surface to be created in a reference system external to the construction machine; 
 access a priority ranking of a plurality of possible sensor sub-sets selected from the set of sensors; 
 determine data representative of a cross-sectional profile of the design surface defined by an intersection of the design surface by an imaginary plane normal to the longitudinal frame axis and including the rotational axis of the milling drum at a selected position and orientation of the milling drum in the reference system external to the construction machine; 
 determine a preferred sensor sub-set that is usable to create at least a portion of the cross-sectional profile of the design surface at the selected position and orientation of the milling drum in the reference system external to the construction machine and that has a highest priority ranking of all usable sensor sub-sets; and 
 automatically maintain or switch control of the milling depth to use the preferred sensor sub-set. 
   
     
     
         2 . The construction machine of  claim 1 , wherein:
 the selected position and orientation of the milling drum in the reference system external to the construction machine is a current position and orientation of the milling drum in the reference system external to the construction machine.   
     
     
         3 . The construction machine of  claim 1 , wherein:
 the selected position and orientation of the milling drum in the reference system external to the construction machine is a predicted future position and orientation of the milling drum in the reference system external to the construction machine.   
     
     
         4 . The construction machine of  claim 3 , wherein:
 the controller is further configured such that the automatically maintaining or switching control of the milling depth to use the preferred sensor sub-set is performed at least by a time when the milling drum reaches the predicted future position and orientation of the milling drum in the reference system external to the construction machine.   
     
     
         5 . The construction machine of  claim 3 , wherein:
 the controller is further configured such that the automatically maintaining or switching control of the milling depth to use the preferred sensor sub-set is performed prior to a time when the milling drum reaches the predicted future position and orientation of the milling drum in the reference system external to the construction machine.   
     
     
         6 . The construction machine of  claim 1 , wherein:
 the controller is further configured such that the determining of the preferred sensor sub-set further includes:
 determining all sensor sub-sets that are usable to create the at least a portion of the cross-sectional profile of the design surface at the selected position and orientation of the milling drum in the reference system external to the construction machine; and 
 selecting the usable sub-set having the highest priority ranking. 
   
     
     
         7 . The construction machine of  claim 1 , wherein:
 the controller is further configured such that the determining of the preferred sensor sub-set further includes:
 determining whether the sensor sub-set having the highest priority ranking is usable to create the at least a portion of the cross-sectional profile of the design surface at the selected position and orientation of the milling drum in the reference system external to the construction machine; 
 selecting the sensor sub-set having the highest priority ranking if the sensor sub-set having the highest priority ranking is usable; and 
 if the sensor sub-set having the highest priority ranking is not usable, then determining whether a sensor sub-set having a next highest priority ranking is usable to create the at least a portion of the cross-sectional profile of the design surface at the selected position and orientation of the milling drum in the reference system external to the construction machine. 
   
     
     
         8 . The construction machine of  claim 1 , wherein:
 the set of sensors includes at least:
 a left side plate sensor; 
 a right side plate sensor; and 
 a cross slope sensor; and 
   the possible sensor sub-sets include at least:
 the left and right side plate sensors; 
 the left side plate sensor and the cross slope sensor; and 
 the right side plate sensor and the cross slope sensor. 
   
     
     
         9 . The construction machine of  claim 8 , wherein:
 the priority ranking of the plurality of possible sensor sub-sets is:
 first priority ranking is a currently used sub-set; 
 second priority ranking is the left and right side plate sensors; and 
 third priority ranking is any one of the remaining possible sensor sub-sets. 
   
     
     
         10 . The construction machine of  claim 8 , wherein:
 the set of sensors further includes:
 a left leading sensor in front of the milling drum; and 
 a right leading sensor in front of the milling drum; and 
   the possible sensor sub-sets further include:
 the left and right leading sensors; 
 the left leading sensor and the cross slope sensor; and 
 the right leading sensor and the cross slope sensor. 
   
     
     
         11 . The construction machine of  claim 10 , wherein:
 the priority ranking of the plurality of possible sensor sub-sets is:
 first priority ranking is a currently used sub-set; 
 second priority ranking is the left and right side plate sensors; 
 third priority ranking is the left and right leading sensors; 
 fourth and fifth priority rankings are one of the side plate sensors and the opposite side leading sensor; 
 sixth and seventh priority rankings are either of the left or right side plate sensors and the cross slope sensor; and 
   eighth and ninth priority rankings are either of the left or right leading sensors and the cross slope sensor.   
     
     
         12 . The construction machine of  claim 1 , wherein:
 the data representative of the cross-sectional profile of the design surface includes data representative of the cross-sectional profile of the design surface at locations laterally outside of the milling drum.   
     
     
         13 . The construction machine of  claim 1 , wherein:
 the data representative of the cross-sectional profile of the design surface includes data corresponding to first and second ends of the milling drum and at least one intermediate point on the milling drum between the first and second ends.   
     
     
         14 . The construction machine of  claim 1 , wherein:
 the data representative of the cross-sectional profile of the design surface includes data representative of at least three points on the cross-sectional profile of the design surface.   
     
     
         15 . The construction machine of  claim 1 , wherein:
 the controller is further configured such that the determining of the preferred sensor sub-set further includes:   detecting a discontinuity in the cross-sectional profile of the design surface at the selected position and orientation of the milling drum in the reference system external to the construction machine.   
     
     
         16 . The construction machine of  claim 15 , wherein:
 the controller is further configured such that the determining of the preferred sensor sub-set further includes:   if the discontinuity is a crown of the cross-sectional profile lying in a path of the milling drum, selecting a portion of the cross-sectional profile on one side of the discontinuity to be milled by the milling drum.   
     
     
         17 . The construction machine of  claim 15 , wherein:
 the controller is further configured such that the determining of the preferred sensor sub-set further includes:   if the discontinuity is a trough of the cross-sectional profile lying in a path of the milling drum, selecting a preliminary cut to be made by the milling drum such that no part of the milling drum mills below the cross-sectional profile.   
     
     
         18 . The construction machine of  claim 1 , wherein:
 the controller is further configured such that the determining of the preferred sensor sub-set further includes:   determining that the preferred sensor sub-set is both theoretically usable and is currently operative.   
     
     
         19 . The construction machine of  claim 1 , wherein:
 the design surface data set includes x, y and z coordinate data of the design surface.