Work assist device for work machine and method for recognizing construction surface at work site

Abstract

A work assist device includes a body coordinates information acquiring unit, a body orientation information acquiring unit, a work member position information acquiring unit, a specific part coordinates computing unit, a placement information receiving unit, a distance information input unit, a construction surface computing unit, a storage unit, and a construction information output unit. The specific part coordinates computing unit can compute absolute coordinates of a specific part of a work member, from acquired information from each acquiring unit. The construction surface computing unit determines an equation for a construction surface in an absolute coordinate system at a work site, from absolute coordinates of three ground reference points at which the specific part is placed in order and three pieces of distance information indicating a distance from the ground reference points to the construction surface.

1 . A work assist device of a work machine including: a machine body having a traveling unit capable of traveling on a ground; and a work member supported by the machine body in such a way as to be capable of moving relative to the machine body and configured to excavate the ground, the work assist device being configured to assist in work of forming, by the work machine, a given construction surface on a work site, and the work assist device comprising:
 a body coordinates information acquiring unit configured to acquire body coordinates information that is information on absolute coordinates of a body reference point at the work site, the body reference point being set on the machine body in advance;   a body orientation information acquiring unit configured to acquires body orientation information that is information on an orientation of the machine body with respect to the body reference point;   a work member position information acquiring unit configured to acquire work member position information that is information on a relative position of the work member to the machine body;   a specific part coordinates computing unit configured to compute and output absolute coordinates of a specific part of the work member at the work site, based on the body coordinates information acquired by the body coordinates information acquiring unit, on the body orientation information acquired by the body orientation information acquiring unit, and on the work member position information acquired by the work member position information acquiring unit;   a placement information receiving unit configured to receive pieces of placement information that is information indicating that the specific part of the work member is placed at least at three ground reference points associated with the construction surface according to at least traveling of the traveling unit;   a storage unit that stores absolute coordinates of the specific part as absolute coordinates of the at least three ground reference points at the work site, respectively, the absolute coordinates of the specific part being computed by the specific part coordinates computing unit in correspondence to the placement information receiving unit's receiving the placement information at the at least three ground reference points;   a distance information input unit configured to receive input of at least three pieces of distance information that is information indicating a distance from each of the at least three ground reference points to the construction surface in a vertical direction;   a construction surface computing unit that computes an equation for the construction surface in an absolute coordinate system of the work site, from the absolute coordinates of the at least three ground reference points, the absolute coordinates being stored in the storage unit, and the at least three pieces of distance information input to the distance information input unit; and   a construction surface information output unit that outputs information on the equation for the construction surface computed by the construction surface computing unit.   
     
     
         2 . The work assist device of the work machine, according to  claim 1 , wherein
 the construction surface computing unit computes absolute coordinates of at least three virtual reference points located respectively below the at least three ground reference points, from the absolute coordinates of the at least three ground reference points and the at least three pieces of distance information, and computes the equation for the construction surface, based on the computed absolute coordinates of the at least three virtual reference points.   
     
     
         3 . The work assist device of the work machine, according to  claim 2 , wherein
 the at least three ground reference points include three specific ground reference points,   the distance information input unit receives input of three pieces of specific distance information indicating a distance from each of the three specific ground reference points to the construction surface in a vertical direction, and   the construction surface computing unit computes absolute coordinates of three specific virtual reference points located respectively below the three specific ground reference points, from the absolute coordinates of the three specific ground reference points and the three pieces of specific distance information, and computes an equation for a plane passing through the computed three specific virtual reference points, as the equation for the construction surface.   
     
     
         4 . The work assist device of the work machine, according to  claim 2 , wherein
 the at least three ground reference points include at least four specific ground reference points,   the distance information input unit receives input of at least four pieces of specific distance information indicating a distance from each of the at least four specific ground reference points to the construction surface in a vertical direction, and   the construction surface computing unit computes absolute coordinates of at least four specific virtual reference points located respectively below the at least four specific ground reference points, from the absolute coordinates of the at least four specific ground reference points and the at least four pieces of specific distance information, and computes an equation for a least-square plane based on the computed at least four specific virtual reference points, as the equation for the construction surface.   
     
     
         5 . The work assist device of the work machine, according to  claim 1 , wherein
 the placement information receiving unit is configured to further receive placement information for checking indicating that the specific part is placed on the at least one ground reference point for checking associated with the construction surface according to traveling of the traveling unit,   the storage unit is configured to store absolute coordinates of the specific part as absolute coordinates of the at least one ground reference point for checking at the work site, the absolute coordinates of the specific part being computed by the specific part coordinates computing unit, in correspondence to the placement information receiving unit's receiving the placement information for checking,   the distance information input unit is configured to receive input of at least one piece of distance information for checking that is information indicating a distance from the at least one ground reference point for checking to the construction surface in a vertical direction,   the construction surface computing unit is configured to compute absolute coordinates of at least one virtual reference point for checking located below the at least one ground reference point for checking, from the absolute coordinates of the at least one ground reference point for checking and the at least one piece of distance information for checking, and   the work assist device further comprises a determining unit that determines whether the equation for the construction surface is within a given allowable range, based on the computed absolute coordinates of the virtual reference point for checking and on the equation for the construction surface computed in advance by the construction surface computing unit.   
     
     
         6 . The work assist device of the work machine, according to  claim 1 , wherein
 the body orientation information acquiring unit includes a body angle sensor that detects and outputs a lift angle, a pitch angle, and a yaw angle of the machine body with respect to the body reference point, as the body orientation information.   
     
     
         7 . The work assist device of the work machine, according to  claim 1 , wherein
 the body coordinates information acquiring unit acquires the body coordinates information, using a global positioning satellite system or a total station.   
     
     
         8 . The work assist device of the work machine, according to  claim 1 , wherein
 the work assist device further comprises a display unit configured to display information on the equation for the construction surface, the information being output from the construction surface information output unit.   
     
     
         9 . The work assist device of the work machine, according to  claim 8 , wherein
 the display unit is configured to display also information on a relative position between the construction surface and the specific part, based on absolute coordinates of the specific part output from the specific part coordinates computing unit.   
     
     
         10 . The work assist device of the work machine, according to  claim 1 , wherein
 the work member of the work machine includes an earth-removing blade and an earth-removing blade support supporting the earth-removing blade, the earth-removing blade support being supported by the machine body in such a way as to be capable of swinging about a lift rotating shaft extending in a left-to-right direction, and   the specific part coordinates computing unit is configured to compute and output absolute coordinates of a specific part of the earth-removing blade, as a specific part of the work member at the work site.   
     
     
         11 . The work assist device of the work machine, according to  claim 10 , wherein
 the work member position information acquiring unit includes an earth-removing blade angle sensor configured to detect and output a lift angle about a lift rotating shaft of the earth-removing blade, as the work member position information.   
     
     
         12 . The work assist device of the work machine, according to  claim 11 ,
 the earth-removing blade of the work member is supported by the earth-removing blade support in such a way as to be capable of swinging about a tilt rotating shaft extending in a left-to-right direction, and   the earth-removing blade angle sensor is configured to detect and output also a tilt angle about a tilt rotating shaft of the earth-removing blade, as the work member position information.   
     
     
         13 . A method of recognizing a construction surface at a work site, the method comprising:
 preparing a work machine including a machine body having a traveling unit configured to travel on a ground and a work member supported by the machine body in such a way as to be capable of moving relative to the machine body, the work member being configured to excavate the ground, and preparing the work assist device of the work machine according to  claim 1 ;   placing the specific part of the work member in order at the at least three ground reference points associated with the construction surface, according to at least traveling of the traveling unit and storing absolute coordinates of the specific part in the storage unit as absolute coordinates of each of the ground reference points, the absolute coordinates of the specific part being computed by the specific part coordinates computing unit in correspondence to each of the ground reference points;   inputting at least three pieces of distance information to the distance information input unit, the distance information indicating a distance from each of the at least three ground reference points to the construction surface in a vertical direction;   computing an equation for the construction surface in an absolute coordinate system of the work site, from the absolute coordinates of the at least three ground reference points, the absolute coordinates being stored in the storage unit, and the at least three pieces of distance information input to the distance information input unit; and   outputting information on the equation for the construction surface computed by the construction surface computing unit and, based on the output information, allowing a worker to recognize a position of the construction surface at the work site.   
     
     
         14 . A method of recognizing a construction surface at a work site, the method comprising:
 preparing a work machine including a machine body having a traveling unit configured to travel on a ground and a work member supported by the machine body in such a way as to be capable of moving relative to the machine body, the work member being configured to excavate the ground, and preparing the work assist device of the work machine according to  claim 10 ;   placing the specific part of the work member in order at the at least three ground reference points associated with the construction surface, according to at least traveling of the traveling unit and storing absolute coordinates of the specific part in the storage unit as absolute coordinates of each of the ground reference points, the absolute coordinates of the specific part being computed by the specific part coordinates computing unit in correspondence to each of the ground reference points;   inputting at least three pieces of distance information to the distance information input unit, the distance information indicating a distance from each of the at least three ground reference points to the construction surface in the vertical direction;   computing an equation for the construction surface in an absolute coordinate system of the work site, from the absolute coordinates of the at least three ground reference points, the absolute coordinates being stored in the storage unit, and the at least three pieces of distance information input to the distance information input unit;   outputting information on the equation for the construction surface computed by the construction surface computing unit and, based on the output information, allowing a worker to recognize a position of the construction surface at the work site;   providing the work site with a reference member for checking including a straight part that is parallel to the construction surface and that is perpendicular to a direction of traveling of the traveling body of the work machine in a plan view;   operating the work machine to align a lower end part of the earth-removing blade, the lower end part extending in a left-to-right direction, with the straight part of the reference member for checking; and   comparing a distance from a left end of the lower end part of the earth-removing blade to the construction surface with a distance from a right end of the lower end part of the same to the construction surface to check whether the computed equation for the construction surface is within a given range.