Patent Publication Number: US-2021178592-A1

Title: Scanner controller and scanner control system

Description:
RELATED APPLICATIONS 
     The present application claims priority to Japanese Patent Application Number 2019-226796 filed Dec. 16, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a scanner controller and a scanner control system. 
     2. Description of the Related Art 
     A technology of irradiating a workpiece with a laser beam from a position distant from the workpiece to perform welding is called remote laser welding. A Galvano scanner is one of the schemes for controlling a machining path in remote laser welding. The Galvano scanner (hereafter, simply referred to as a scanner) is a device that scans an arbitrary path with laser light by operating one or more mirrors (for example, two mirrors when laser control in X and Y directions is performed) in an optical system for laser. A remote laser welding robot system in which such a scanner is attached to the end of a robot, that is, a hand portion of a robot has been put into practice (see  FIG. 7 ). In a remote laser welding robot system, since a scanner is operated while a robot is being moved, welding can be performed on a more complex machining path than in a case where a scanner is operated alone. Such a machining scheme performed by operating a scanner while moving a robot is called on-the-fly. 
     Typically, a robot controller that controls a robot controls a motor of the robot based on a program of movement command for the robot. On the other hand, a scanner controller that controls a scanner controls a motor of the scanner and the output of laser based on a program in which irradiation positions of laser and output conditions (power) of the laser are described. In the remote laser welding robot system described above, a robot controller transmits data of the position and attitude of an operating robot to a scanner controller, and the scanner controller creates an actual machining path while taking the operation of the robot into consideration (see Japanese Patent Application Laid-Open No. 2007-283402). The respective programs are created as programs synchronized by a path creation device. 
     As described above, the controller which controls the scanner and the controller of the robot in which the scanner is attached to the hand portion are implemented as separate devices. Further, data of the position and attitude of the robot is transmitted and received between these separate controllers, and thereby the operation of the robot and the operation of the scanner are synchronized with each other. However, it is difficult for the scanner controller to accurately recognize the position and attitude of the robot all the time. To improve synchronousness of the position and attitude of the scanner controller and the robot, both the scanner and the robot are required to be stationary each other when execution of a program is started in the scanner controller. 
     SUMMARY OF THE INVENTION 
     Thus, there is a problem of inability of starting on-the-fly at an optional arbitrary position. With a function of on-the-fly, the scanner controller can control the scanner to emit laser light to a desired position on a workpiece. However, since the scanner controller is unable to always recognize what degree the current position of the robot is shifted from the ideal value, variation may occur in machining results. Further, over-travel (OT) of the scanner may be caused. 
     Thus, there is a demand for a mechanism that can synchronize a scanner and a robot with each other from an optional position. 
     When creating paths of a robot and a scanner, a path generation device provided in a scanner control system of the present invention performs a simulation of a scanner operation and, based on a simulation result, creates a program in which a world coordinates of a scanner path and local coordinates of the scanner are included in the same block. The scanner that has received such a program starts machining using an on-the-fly function when the local coordinate value calculated from the world coordinate value included in the program and the position of the robot enters a certain range with respect to the local coordinate value of the same block. 
     A scanner controller according to one aspect of the present invention is a scanner controller that controls a scanner attached to an end of a robot and configured to scan a predetermined path with laser light based on a scanner control program to machine a workpiece, and a block of a position instruction in which a position in a world coordinate system and a position in a local coordinate system of a path of the laser light are associated with each other is included in the scanner control program, and the scanner controller includes: a program analysis unit that analyzes the scanner control program and creates a movement command for a drive unit of the scanner based on a position in a local coordinate system instructed by the block; an interpolation unit that creates interpolation data for each interpolation cycle based on the movement command; a position calculation unit that calculates a current position of the scanner in a local coordinate system based on a position and attitude in the world coordinate system of the robot and a position in the world coordinate system instructed by the block; an on-the-fly start determination unit that determines to start machining using an on-the-fly function when a distance between a position in a local coordinate system calculated in the position calculation unit and a position in a local coordinate system instructed by the block is below a predetermined threshold defined in advance; and a motor output unit that performs control of the drive unit of the scanner based on interpolation data created by the interpolation unit when the on-the-fly start determination unit determines to start machining using an on-the-fly function. 
     A scanner control system according to another aspect of the present invention includes: a path creation device that performs a simulation based on a specified machining path and creates a robot control program and a scanner control program including a block of a position instruction in which a position in a world coordinate system and a position in a local coordinate system of a path of laser light are associated with each other; a robot controller that controls an operation of a robot based on the robot control program; and a scanner controller that controls a scanner attached to an end of the robot and configured to scan a predetermined path with laser light based on the scanner control program to machine a workpiece. The scanner controller further includes a program analysis unit that analyzes the scanner control program and creates a movement command for a drive unit of the scanner based on a position in a local coordinate system instructed by the block, an interpolation unit that creates interpolation data for each interpolation cycle based on the movement command, a position calculation unit that calculates a current position of the scanner in a local coordinate system based on a position and attitude in the world coordinate system of the robot and a position in the world coordinate system instructed by the block, an on-the-fly start determination unit that determines to start machining using an on-the-fly function when a distance between a position in a local coordinate system calculated in the position calculation unit and a position in a local coordinate system instructed by the block is below a predetermined threshold defined in advance, and a motor output unit that performs control of the drive unit of the scanner based on interpolation data created by the interpolation unit when the on-the-fly start determination unit determines to start machining using an on-the-fly function. 
     In the present invention, with the configuration described above, the scanner controller recognizes a displacement of the robot from an ideal position, and thereby synchronization of the on-the-fly function is no longer required to be started in a state where the scanner and the robot are stationary each other. Further, it is possible to switch a plurality of programs during the operation of the robot to perform machining using the on-the-fly function. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a hardware configuration of a path creation device provided in a scanner control system according to one embodiment; 
         FIG. 2  is a schematic diagram of a hardware configuration of a scanner controller and a robot controller provided in the scanner control system according to one embodiment; 
         FIG. 3  is a block diagram illustrating a general function of the path creation device according to one embodiment; 
         FIG. 4  is a block diagram illustrating a general function of the scanner controller according to one embodiment; 
         FIG. 5  is a block diagram illustrating a general function of a robot controller according to one embodiment; 
         FIG. 6  is a diagram illustrating an example of machining using a plurality of scanner control programs; 
         FIG. 7  is a diagram illustrating on-the-fly machining according to the related art; and 
         FIG. 8  is a diagram illustrating an operation of an on-the-fly start determination unit. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a schematic diagram of a hardware configuration illustrating a primary part of a path creation device provided in a scanner control system according to one embodiment of the present invention. 
     A scanner control system  1  according to the present embodiment is configured such that a scanner controller  3  that controls a scanner  4 , a robot controller  5  that controls a robot  6  in which the scanner  4  is attached to the end of a hand, and a path creation device  2  that creates a program used for instructing the scanner controller  3  and the robot controller  5  for motion paths are connected to each other via a wired or wireless network  7 , for example. 
     The path creation device  2  provided in the scanner control system  1  can be mounted on a personal computer connected to the scanner controller  3  and the robot controller  5  via the network  7 , for example. The CPU  211  provided in the path creation device  2  according to the present embodiment is a processor that generally controls the path creation device  2 . The CPU  211  reads a system program stored in a ROM  212  via a bus  222  and controls the overall path creation device  2  in accordance with the system program. A RAM  213  temporarily stores temporary calculated data or display data and various externally input data or the like. 
     A nonvolatile memory  214  is formed of a memory device, a solid state drive (SSD), or the like backed up by a battery (not illustrated), for example, and the storage state is held even when the path creation device  2  is powered off. The nonvolatile memory  214  stores data loaded from an external device (not illustrated), data input via an input device  271 , data acquired from the scanner controller  3 , the robot controller  5 , or the like via an interface  220 , or the like. The data stored in the nonvolatile memory  214  may be loaded into the RAM  213  when executed or used. Further, various system programs such as a known analysis program are written in advance in the ROM  212 . 
     The interface  220  is an interface used for connecting the CPU  211  of the path creation device  2  to the wired or wireless network  7 . The scanner controller  3 , the robot controller  5 , a fog computer, a cloud server, or the like are connected to the network  7  to transfer data to and from the path creation device  2 . 
     On a display device  270 , each data loaded on a memory device, data obtained as a result of execution of a program or the like, or the like are output and displayed via an interface  217 . Further, the input device  271  formed of a keyboard, a pointing device, or the like passes an instruction, data, or the like based on a worker&#39;s operation to the CPU  211  via an interface  218 . 
       FIG. 2  is a schematic diagram of a hardware configuration illustrating primary parts of the scanner controller and the robot controller provided in the scanner control system according to one embodiment of the present invention. 
     A CPU  311  provided in the scanner controller  3  according to the present embodiment is a processor that generally controls the scanner controller  3 . The CPU  311  reads a system program stored in a ROM  312  via a bus  322  and controls the overall scanner controller  3  in accordance with the system program. A RAM  313  temporarily stores temporary calculated data or display data and various externally input data or the like. 
     A nonvolatile memory  314  is formed of a memory device, a solid state drive (SSD), or the like backed up by a battery (not illustrated), for example, and the storage state is held even when the scanner controller  3  is powered off. The nonvolatile memory  314  stores data loaded from an external device (not illustrated), data input via an input device  371 , data acquired from the path creation device  2  or the like via an interface  321 , data acquired from the robot controller  5  via an interface  315 , or the like. The data stored in the nonvolatile memory  314  may be loaded into the RAM  313  when executed or used. Further, various system programs such as a known analysis program are written in advance in the ROM  312 . 
     The scanner controller  3  is connected to the scanner  4  via an interface  320 . The CPU  311  executes a program acquired from the path creation device  2 , for example, and outputs an instruction to control a motor provided in the scanner  4  or an instruction to control a laser oscillator (not illustrated) via the interface  320 . Further, the CPU  311  acquires data related to the operation status of the scanner  4  via the interface  320 . 
     The interface  321  is an interface used for connecting the CPU  311  of the scanner controller  3  to the wired or wireless network  7 . The path creation device  2 , the robot controller  5 , a fog computer, a cloud server, or the like are connected to the network  7  and transfer data to and from the scanner controller  3 . 
     On a display device  370 , each data loaded on a memory device, data obtained as a result of execution of a program or the like, or the like are output and displayed via an interface  317 . Further, the input device  371  formed of a keyboard, a pointing device, or the like passes an instruction, data, or the like based on a worker&#39;s operation to the CPU  311  via an interface  318 . 
     The CPU  511  provided in the robot controller  5  according to the present embodiment is a processor that generally controls the robot controller  5 . The CPU  511  reads a system program stored in a ROM  512  via a bus  522  and controls the overall robot controller  5  in accordance with the system program. A RAM  513  temporarily stores temporary calculated data or display data and various externally input data or the like. 
     A nonvolatile memory  514  is formed of a memory device, a solid state drive (SSD), or the like backed up by a battery (not illustrated), for example, and the storage state is held even when the robot controller  5  is powered off. The nonvolatile memory  514  stores data loaded from an external device (not illustrated), data input via an input device  571 , data acquired from the path creation device  2  or the like via an interface  521 , data acquired from the scanner controller  3  via an interface  515 , or the like. The data stored in the nonvolatile memory  514  may be loaded into the RAM  513  when executed or used. Further, various system programs such as a known analysis program are written in advance in the ROM  512 . 
     The robot controller  5  is connected to the robot  6  via an interface  520 . The CPU  511  executes a program acquired from the path creation device  2 , for example, and outputs an instruction to control a motor that drives each axis of the robot  6  via the interface  520 . Further, the CPU  511  acquires data related to the operation status of the robot  6  via the interface  520 . 
     The interface  521  is an interface used for connecting the CPU  511  of the robot controller  5  to the wired or wireless network  7 . The path creation device  2 , the scanner controller  3 , a fog computer, a cloud server, or the like are connected to the network  7  and transfer data to and from the robot controller  5 . 
     On a display device  570 , each data loaded on a memory device, data obtained as a result of execution of a program or the like, or the like are output and displayed via an interface  517 . Further, the input device  571  formed of a keyboard, a pointing device, or the like passes an instruction, data, or the like based on a worker&#39;s operation to the CPU  511  via an interface  518 . 
     The scanner controller  3  and the robot controller  5  may be connected to a communication line  8  that is different from and faster than the network  7 . For example, the robot controller  5  can transmit data related to the position and attitude of the robot  6  to the scanner controller  3  at a high speed via the communication line  8 . 
       FIG. 3  illustrates the function of the path creation device  2  provided in the scanner control system  1  according to the first embodiment of the present invention as a schematic block diagram. 
     Each function of the path creation device  2  according to the present embodiment is implemented when the CPU provided in the path creation device  2  illustrated in  FIG. 1  executes the system program and controls the operation of each unit of the path creation device  2 . 
     The path creation device  2  of the present embodiment has a simulation unit  21 , a program creation unit  23 , and a program transmission unit  25 . 
     The simulation unit  21  is implemented when the CPU  211  provided in the path creation device  2  illustrated in  FIG. 1  executes a system program read from the ROM  212  and an operation process using the RAM  213  or the nonvolatile memory  214  is performed mainly by the CPU  211 . The simulation unit  21  performs a simulation process based on a machining path input by an operator via the input device  271 , for example. The simulation process performed by the simulation unit  21  is to perform teaching and operation of the robot by moving the robot in robot work in a virtual space and create an instruction capable of avoiding an obstacle or the like. 
     The simulation unit  21  links an irradiation position in the world coordinate system instructed by a machining path with an irradiation position in the local coordinate system on which the scanner actually operates. The simulation unit  21  simulates change in the position and attitude of the robot  6  (operation path) for machining a part on the machining path based on the input machining path. Further, the simulation unit  21  simulates change in the position of each motor of the scanner  4  (operation path) for emitting laser to a position on a machining path on a workpiece from the scanner  4  when the position and attitude of the robot  6  is changing. A simulation result from the simulation unit  21  is output to the program creation unit  23 . 
     The program creation unit  23  is implemented when the CPU  211  provided in the path creation device  2  illustrated in  FIG. 1  executes a system program read from the ROM  212  and an operation process using the RAM  213  or the nonvolatile memory  214  is performed mainly by the CPU  211 . The program creation unit  23  calculates an operation path of the robot  6  in the world coordinate system (for example, a coordinate system in which the origin of the robot  6  is the reference position) based on a result of a simulation process performed by the simulation unit  21 . Further, the program creation unit  23  calculates an operation path of the scanner  4  in the world coordinate system and an operation path of the scanner  4  in the local coordinate system of the scanner  4  (for example, a coordinate system in which the origin of the scanner  4  is the reference position) based on a result of a simulation process performed by the simulation unit  21 . Further, the program creation unit  23  creates a robot control program that operates the robot  6  and a scanner control program that operates the scanner  4 , respectively, based on each calculated operation path. 
     The robot control program created by the program creation unit  23  includes a block for an instruction for an operation path of the robot  6  in the world coordinate system. Further, the scanner control program created by the program creation unit  23  includes a block for an instruction in which an operation path of the scanner in the world coordinate system and an operation path of the scanner in the local coordinate system are associated with each other. 
     The program transmission unit  25  is implemented when the CPU  211  provided in the path creation device  2  illustrated in  FIG. 1  executes a system program read from the ROM  212  and an operation process using the RAM  213  or the nonvolatile memory  214  and a communication process using the interface  220  are performed mainly by the CPU  211 . The program transmission unit  25  transmits a robot control program created by the program creation unit  23  to the robot controller  5 . Further, the program transmission unit  25  transmits a scanner control program created by the program creation unit  23  to the scanner controller  3 . 
       FIG. 4  illustrates the function of the scanner controller  3  provided in the scanner control system  1  according to the first embodiment of the present invention as a schematic block diagram. 
     Each function of the scanner controller  3  according to the present embodiment is implemented when the CPU provided in the scanner controller  3  illustrated in  FIG. 2  executes the system program and controls the operation of each unit of the scanner controller  3 . 
     The scanner controller  3  of the present embodiment has a program analysis unit  31 , an interpolation unit  32 , a position calculation unit  33 , an on-the-fly start determination unit  34 , and a motor output unit  36 . 
     The program analysis unit  31  is implemented when the CPU  311  provided in the scanner controller  3  illustrated in  FIG. 2  executes a system program read from the ROM  312  and an operation process using the RAM  313  or the nonvolatile memory  314  is performed mainly by the CPU  311 . The program analysis unit  31  analyzes each block of a scanner control program created by the path creation device  2  and calculates an operation path of the scanner  4 . The program analysis unit  31  creates a movement command for a drive unit of the scanner  4  (a movement command for a laser irradiation position in the local coordinate system) based on the operation path of the scanner  4  in the local coordinate system instructed by the scanner control program. 
     The interpolation unit  32  is implemented when the CPU  311  provided in the scanner controller  3  illustrated in  FIG. 2  executes a system program read from the ROM  312  and an operation process using the RAM  313  or the nonvolatile memory  314  is performed mainly by the CPU  311 . The interpolation unit  32  creates interpolation data indicating a motion amount for each interpolation cycle of each motor that drives the drive unit of the scanner  4  based on a movement command for the drive unit of the scanner  4  created by the program analysis unit  31 . 
     The position calculation unit  33  is implemented when the CPU  311  provided in the scanner controller  3  illustrated in  FIG. 2  executes a system program read from the ROM  312  and an operation process using the RAM  313  or the nonvolatile memory  314  and a communication process using the interface  315  are performed mainly by the CPU  311 . The position calculation unit  33  receives data of a position and attitude of the robot  6  in the world coordinate system transmitted from the robot controller  5  via the communication line  8  and calculates the position of the scanner  4  in the local coordinate system based on the received data of the position and attitude of the robot  6  and the position in the world coordinate system instructed from the scanner control program analyzed by the program analysis unit  31 . 
     The on-the-fly start determination unit  34  is implemented when the CPU  311  provided in the scanner controller  3  illustrated in  FIG. 2  executes a system program read from the ROM  312  and an operation process using the RAM  313  or the nonvolatile memory  314  is performed mainly by the CPU  311 . As illustrated in  FIG. 8  as an example, the on-the-fly start determination unit  34  determines to start machining of a workpiece using the on-the-fly function when the distance between the position of the scanner  4  in the local coordinate system calculated by the position calculation unit  33  and the start position in a movement command in the local coordinate system analyzed by the program analysis unit  31  becomes below a predetermined threshold defined in advance. 
     The motor output unit  36  is implemented when the CPU  311  provided in the scanner controller  3  illustrated in  FIG. 2  executes a system program read from the ROM  312  and an operation process using the RAM  313  or the nonvolatile memory  314  and an input/output process using the interface  320  are performed mainly by the CPU  311 . Once start of machining of a workpiece using the on-the-fly function is determined by the on-the-fly start determination unit  34 , the motor output unit  36  outputs interpolation data created by the interpolation unit  32  to each motor that drives the drive unit of the scanner  4  and performs drive control of the motor. 
       FIG. 5  illustrates the function of the robot controller  5  provided in the scanner control system  1  according to the first embodiment of the present invention as a schematic block diagram. 
     Each function of the robot controller  5  according to the present embodiment is implemented when the CPU provided in the robot controller  5  illustrated in  FIG. 2  executes the system program and controls the operation of each unit of the robot controller  5 . 
     The robot controller  5  of the present embodiment has a program analysis unit  51 , an interpolation unit  52 , a motor output unit  56 , and a position output unit  58 . 
     The program analysis unit  51  is implemented when the CPU  511  provided in the robot controller  5  illustrated in  FIG. 2  executes a system program read from the ROM  512  and an operation process using the RAM  513  or the nonvolatile memory  514  is performed mainly by the CPU  511 . The program analysis unit  51  analyzes each block of a robot control program created by the path creation device  2  and calculates the operation path of the robot  6 . 
     The interpolation unit  52  is implemented when the CPU  511  provided in the robot controller  5  illustrated in  FIG. 2  executes a system program read from the ROM  512  and an operation process using the RAM  513  or the nonvolatile memory  514  is performed mainly by the CPU  511 . The interpolation unit  52  creates interpolation data indicating a motion amount for each interpolation cycle of each motor that drives an axis of the robot  6  based on a movement command for the drive unit of the robot  6  created by the program analysis unit  51 . 
     The motor output unit  56  is implemented when the CPU  511  provided in the robot controller  5  illustrated in  FIG. 2  executes a system program read from the ROM  512  and an operation process using the RAM  513  or the nonvolatile memory  514  and an input/output process using the interface  520  are performed mainly by the CPU  511 . The motor output unit  56  outputs interpolation data created by the interpolation unit  52  to each motor that drives the shaft of the robot  6  and performs drive control of the motor. 
     The position output unit  58  is implemented when the CPU  511  provided in the robot controller  5  illustrated in  FIG. 2  executes a system program read from the ROM  512  and an operation process using the RAM  513  or the nonvolatile memory  514  and an input/output process using the interface  515  are performed mainly by the CPU  511 . The position output unit  58  creates data related to the current position and attitude in the world coordinate system of the robot based on interpolation data (position instruction) output from the motor output unit  56  to each motor that drives an axis of the robot  6  or position information fed back from each motor and outputs the created data related to the position and attitude to the scanner controller  3 . 
     In the scanner control system  1  having the configuration described above, the scanner control program that operates the scanner  4  created by the path creation device  2  includes a block in which the position in the world coordinate system and the position in the local coordinate system of the scanner  4  are associated with each other. While the robot controller  5  controls the operation of the robot  6  in accordance with the robot control program, the scanner controller  3  waits execution of the program until the position and attitude of the robot  6  approaches a predetermined machining start position instructed by the scanner control program. When the position and attitude of the robot  6  then approaches the machining start position, execution of the scanner control program is started, and machining of a workpiece is started. The difference between data related to the position and attitude of the robot  6  and the coordinate position instructed by the scanner control program indicates a displacement from an ideal position of the robot  6  assumed by the scanner controller  3 , and with knowledge of such a displacement, synchronization of the on-the-fly function is no longer required to be started in a state where the scanner and the robot are stationary each other. 
     In scanner control system  1  having the configuration described above, only the operation of the scanner  4  near the machining position of a workpiece is required to be created as a scanner control program. Thus, as illustrated in  FIG. 6  as an example, a plurality of scanner control programs indicating the operation of the scanner  4  near the machining position of a workpiece can be prepared for a single robot control program and stored in the scanner controller  3 , and when the position and attitude of the robot  6  approaches respective machining start positions, the scanner control programs at respective positions can be executed to perform machining. In such a way, scanner control programs in a series of machining can be created for each machining position, and thus enables flexible adaptation, for example, only some of the scanner control programs may be replaced as needed (for example, when some of the machining positions have a problem, or when the machining shape is intended to be changed for some of the machining positions, or the like). 
     As described above, although one embodiment of the present invention has been described, the present invention is not limited to only the examples in the embodiment described above and may be implemented in various forms with addition of an appropriate change.