Abstract:
A system and method for enhancing a visualization of coordinate points within a robot&#39;s working envelope is disclosed. Part data associated with a position of a part, which may include part offset from a known position, is read using a teach pendant program. The part data is automatically stored within a hidden program instruction of the teach pendant program. The part data may be stored within the part program in a motion instruction associated with a motion line of the teach pendant program.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to robotic systems, and more particularly, to systems and methods for part location during operation of robotic systems including moving conveyors. 
     BACKGROUND OF THE INVENTION 
     Programmable controllers operate elaborate industrial equipment, such as robots, in accordance with a plurality of stored control programs. When executed, each program causes the programmable controller or robot controller to examine the state of the controlled machinery by evaluating signals from one or more sensing devices (e.g., position encoders, temperature sensors, or pressure sensors) and to operate the machinery (e.g., by controlling the output voltage for servo motors, or energizing/de-energizing discrete components) based on a procedural framework, the sensor signals and, if necessary, more complex processing. As an added complexity, the controlled machinery may further include a moving conveyor system that moves work (e.g. a tool or a part to be serviced by a robot) relative to such robot, requiring additional processing to determine work location relative to the robot to facilitate robotic manipulation of the work. 
     The programmable controller is generally described as a computer-based control unit that is represented by an aggregate of conventional elements. The control unit also supports one or more user interfaces to facilitate operator input of processing programs, commanded positions, and system parameters. Such user interfaces may include teach pendants that allow a programmer to lead a robot through a desired sequence of events by activating the appropriate pendant button or switch, and may include offline PC simulation devices on which a required sequence of functional and positional steps may be written for simulated execution or for actual test execution in combination with a teach pendant. 
     When establishing a processing program, it is necessary to establish a physical or geometrical relationship between the robot and work to be serviced by the robot. Users want to understand where in the robot envelope a position can and cannot be reached. 
     To establish physical or geometrical coordinate points precisely within the robot&#39;s working envelope using conventional teach pendant systems, an operator typically manually controls the robot, including a conveyor holding the work, and physically teaches the coordinate points by activating an appropriate pendant button or switch. Essentially, a user must manually move work down a conveyor line and then manually move an associated robot to establish a taught position. Program verification and program touch-up also typically require a user to manually lead or walk a robot through the programmed steps. Programming, program verification and program touch-up are typically performed iteratively and may take significant time. 
     Undesirably, Cartesian conveyor tracking systems may be difficult to use primarily because robot manipulator joint angle locations can change for a given point on the part. A user may teach a point on the work such that the robot can reach that point. However, if the work is moved using the conveyor, the robot must change its posture/joint angles to touch the same point. Moreover, there is no guarantee that the point on the work can be reached by the robot once the work has been moved. And finally, even if a plurality of positions are taught using a teach pendant in the context of establishing a processing program, the teach pendant itself provides no feedback about the viability and acceptability of a processing program so established. Instead, the processing program must be executed to determine acceptability. If the processing program is determined to be unacceptable, then further iterations of teach pendant programming, verification, and touch-up must occur. 
     Alternatively, a user may utilize a known offline simulation program to develop a processing program for a robot. During execution of the simulation program, data representative of the simulation may be recorded in external files. The user may then manually review and search the data to determine acceptable physical or geometrical coordinate points within the robot&#39;s working envelope. However, such data files may be complex and quite large, so that the process of reviewing and searching the data files may require a level of expertise and may further be time consuming. Moreover, existing simulation programs are not capable of capturing data indicative of position for a robot and associated work and using such data for synchronization of the work and the robot for planning and teaching purposes. Lastly, simulation data must be correlated with actual run-time data from a robotic cell to validate that simulated physical and geometrical points are representative of actual points in the work cell. 
     It is therefore desirable to develop a system and method for enhancing a visualization of physical or geometrical coordinate points within a robot&#39;s working envelope, wherein the system and method overcome the shortcomings of the prior art. 
     SUMMARY OF THE INVENTION 
     Concordant and consistent with the present invention, a system and method for enhancing a visualization of coordinate points within a robot&#39;s working envelope has surprisingly been discovered. 
     In one embodiment of the method, part data associated with a position of a part is read using a teach pendant program. The part data may include part offset from a known position. The part data is automatically stored within a part program instruction of the teach pendant program. The part data may be stored within the part program in a motion instruction associated with a motion line of the teach pendant program. Additionally, the part program instruction may be hidden from a user of the teach pendant program. 
     In another embodiment, a robot data associated with a position of the robot is read using the teach pendant program. The robot data is automatically stored within a robot program instruction of the teach pendant program, and may be synchronized with the part data. The part and robot data may be extracted from the respective part and robot program instructions by a one of a programmable controller, a teach pendant controller, and an offline simulation having access to the teach pendant program to provide a graphical representation of the position of the part on a display associated with the robot. The part program instruction and the robot program instruction may be executed by a programmable controller to place one of the part and the robot at a location indicated by the part data and the robot data. A user of the teach pendant program may place one of the part and the robot at a desired location by reference to the graphical representation on the display. 
     In another embodiment, a programmable controller having a robot is disclosed. The programmable controller includes a teach pendant operating pursuant to a teach pendant program. A processor is coupled to the teach pendant for accepting data associated with at least one of a part position of a part and a robot position of the robot. The processor automatically stores the data within a program instruction within the teach pendant program. The data may include a part offset relative to a known position. Additionally, the program instruction may be hidden from a user. The programmable controller may further include a display device, wherein the programmable controller accesses the program instruction, extracts the data from the program instruction, and provides a graphical representation of the data on the display device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above, as well as other advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description, particularly when considered in the light of the drawings described herein. 
         FIGS. 1A and 1B  are perspective elevational views illustrating the problems addressed by the present invention. 
         FIG. 2  is a schematic view of a system incorporating the present invention. 
         FIG. 3  is a schematic flow diagram of a method for data collection of nodes of interest within a robot&#39;s working envelope, according to an embodiment of the invention. 
         FIG. 4  is a schematic flow diagram of a method for data collection of nodes of interest within a robot&#39;s working envelope, according to an embodiment of the invention. 
         FIG. 5  is a schematic flow diagram of a simulation method using the collected nodes of interest, according to an embodiment of the invention. 
         FIG. 6  is a schematic flow diagram of a display method using the collected nodes of interest, according to an embodiment of the invention. 
         FIGS. 7A and 7B  are perspective elevational views of a display method using the collected nodes of interest, according to an embodiment of the invention 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description and appended drawings describe and illustrate various embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. 
     A representative work cell  10  including a robot  12  and a moving conveyor system  14  moving an item of work  16  relative to the robot  12  is described with reference to  FIGS. 1A and 1B . The item of work  16  may be a part, a tool, a fixture, or any other item intended to be serviced by the robot  12 . It is understood that the moving conveyor system  14  may move the item of work  16  in any dimension and direction, including rotationally, as required to allow the robot  12  to service the item of work  16 . The robot  12  may include one or more articulating arms  18 , each of which may include one or more joints  20  that provide pivotal, rotational or other movement relative to the item of work  16 . As shown in  FIG. 1A , the work cell  10  may include more than one robot  12 , as required, and may further include one or more sensors (not shown) to detect the position and orientation of the item of work  16 . 
     The work cell  10  may be designed for the robot  12  to specifically service a known point  22  on the item of work  16 . It is understood that the robot  12  is interconnected to a programmable controller (not shown), and may further be connected to a teach pendant (not shown) useful for allowing a programmer to lead the robot  12  through a desired sequence of events relative to the item of work  16 . Such a programmable controller including a teach pendant may take the form as disclosed in commonly owned U.S. Pat. No. 6,560,513, the disclosure of which is incorporated by reference herein in its entirety. 
     As noted previously, prior to full operation of a work cell  10 , the programmable controller must be properly programmed by a user to operate the robot  12  based on a desired procedural framework. One method of properly programming operation of the robot  12  requires a user, using the teach pendant, to “teach” the known point  22  on the item of work  16  to the programmable controller such that the robot  12  can reach the known point  22 , as illustrated in  FIG. 1B . If the item of work  16  is moved along the moving conveyor  14 , the articulating arms  18  and the joints  20  of the robot  12  may change posture, angles or may otherwise require movement in order to reach the known point  22 . As illustrated in  FIG. 1A , locations exist along the moving conveyor  14  where it is not possible for the robot  12  to reach the known point  22 . In some instances, only slight movement of the item of work  16  along the moving conveyor  14  may result in a positioning of the known point  22  where the robot  12  cannot reach the known point. 
     During programming processes, a user may manually manipulate the robot  12 , the moving conveyor  14  and the item of work  16  to identify one or more positions of the known point  22  along the moving conveyor  14  where the robot may service the known point  22 . However, a determination of whether the program is acceptable may only be obtained by running the program. As a non-limiting example, if the previously identified position of the known point  22  causes interference between one or more of the robots  12 , then the user will be required to iteratively identify additional positions of the known point  22 , which may take significant time. Additionally, during the programming process, the ability to identify a position at which the robot  12  may service the known point  22  provides no indication of the validity, operability and/or viability of the program being created. 
       FIG. 2  shows a system  60  incorporating the present invention. The system  60  includes at least one programmable controller  62  having a memory  64  for storing a plurality of types of data objects  66 . The memory  64  may be any suitable memory type or combination thereof. The types of data objects  66  include, but are not limited to, user program variables, user TP programs, error logs, system settings, configuration and current states, and system variables. These types of data objects  66  are written in different formats as well as by different programming languages. For example, the format may be different for the error logs, the system variables and the user TP programs. 
     The programmable controller  62  may include a user interface  68  for allowing a user to enter data or programs into the controller  62  or for accessing the data stored therein. The user interface  68  may include a display  70  for displaying the information to the user and a teach pendant  72 . 
     The programmable controller  62  may be a robot controller, wherein in such a case, the controller  62  is coupled to a robot  74  for actively performing a variety of tasks. It is understood that the robot  74  may include a movable conveyor (not shown) for moving an item of work (not shown). It is further understood that the present invention is not limited to robot controllers. As a non-limiting example, the programmable controller  62  may be a passive controller, such as a monitoring device that monitors predetermined conditions. 
     To assist in monitoring operation of the programmable controller  62 , at least one remote computer  76  is coupled to the programmable controller  62  preferably via a functional network  78 . The remote computer  76  may be located in the same room or building as the programmable controller  62 , or it may be located in an entirely different building, which may or may not be located in the same geographic vicinity as the controller  62 . The network  78  may be a local or wide area network of controllers or may be a direct link between devices. 
     Coupled to the remote computer  76  is one or more second user interfaces  80 , which may include a remote computer device such as a simulation computer for entering information regarding the desired data to be accessed. The remote computer  76  also includes a data exchange facilitator  82 , in communication with the user interface  80  and the network  78 , for facilitating data interchange with the programmable controller  62 . 
     The programmable controller  62  may include an interface module  84  coupled to the network  78  for receiving requests for data from the remote computer  76 . The interface module  84  may be coupled to a data converter module  86 , which is in communication with memory  64 , for processing the request and converting data into a comprehensible format that is readable by the user of the remote computer  76 , such as, text, graphics, audio, or tabular format. 
       FIG. 3  is a flow diagram illustrating general steps associated with a programming operation in one embodiment of the invention. At a first process block  110 , a user of a teach pendant  72  creates a part motion instruction for the robot  74 . The part motion instruction may be stored as a data object  66  within the memory  64 , for example. In one embodiment, the part motion instruction is stored as a motion instruction within the teach pendant program, and may require motion of the robot  74 , including an associated moving conveyor, to move both the robot  74  and an item of work to a desired location. In process block  112 , a node of interest is created as a data object  66  that is defined by the desired location of one or both of the robot and the moving conveyor in response to the part motion instruction created by the user. In one embodiment, termination of movement by one or both of the robot and the moving conveyor in response to the part motion instruction may be used to define one or more nodes of interest associated with the part motion instruction. As non-limiting examples, the node of interest may be defined using Cartesian coordinates, vectors, distance from a known point, or the like. In one embodiment, the node of interest is defined as an offset value relative to a known point, such as a detect switch. 
     In process block  114 , the programmable controller  62  stores data indicative of the node of interest created in process block  112  in a hidden robot motion instruction. In process block  116 , the hidden robot motion instruction is stored as a data object  66  within the memory  64 , for example. In one embodiment, the hidden robot motion instruction is stored as a motion instruction within the teach pendant program. The hidden robot motion instruction may be added to the part motion instruction, or it may be added discretely adjacent to or associated with the part motion instruction. It is understood that the user may repeatedly create nodes of interest using process steps  110 ,  112 ,  114  and  116 . In this manner, data indicative of each node of interest may be added to the memory as data objects, or to the teach pendant program as hidden motion instructions. The data indicative of each node of interest is not directly utilized by the user, but may be accessed by any routine, task, interface module or the like interconnected with the programmable controller  62 . 
     According to the embodiment of  FIG. 3 , a hidden robot motion instruction is created any time the user creates a new part motion instruction in the teach pendant program. As shown in  FIG. 4 , the present invention may also be used to add nodes of interest to existing programs during program editing and validation, or may be used in tracking routines to verify locations of nodes of interest. In step  120  of  FIG. 4 , a user may touch up a node of interest. In operation, the user may manipulate the robot  74 , the moving conveyor, or both, using the teach pendant  72 , a remote computer  76 , or any other method used to manipulate the robot  74 . 
     At step  122  of  FIG. 4 , after the user touches up a node of interest, the data objects  66 , or the teach pendant program lines, as applicable, are queried to determine whether a hidden robot instruction exists that contains information indicative of the node of interest being touched. If no such hidden robot instruction exists, the present invention automatically creates the hidden robot instruction storing data indicative of the node of interest being touched in step  124 . The hidden robot motion instruction created thereby may be stored as a data object  66  within the memory  64 , for example. In one embodiment, the hidden robot motion instruction is stored as a motion instruction within the teach pendant program. Once step  122  detects the presence of a hidden robot instruction, or after the hidden robot instruction is created in step  124 , the system resets until the user touches up another node of interest in step  120 . In this manner, additional nodes of interest may be added at any time, even after the programmable controller  62  has been fully programmed by the user. 
     According to an embodiment of the invention, all data indicative of nodes of interest captured and stored within hidden robot motion instructions associated with each node of interest may be stored in the memory  64  and may be accessed by any routine, task, interface module or the like interconnected with the programmable controller  62 , which may further process the data. As a result, the data may be used to review the programs and to manipulate the robot  74 . For example, as shown in  FIG. 5 , in process step  130 , a user may obtain a robot position, either by moving the robot  74  to an actual position or through simulated movement of the robot. In process step  132 , the present invention is able to identify one or more nodes of interest associated with the robot position obtained in step  130  that is included within the programmable controller program. In addition to identifying one or more nodes of interest, the present invention may also identify any hidden motion instructions included within the programmable controller program associated with the one or more nodes of interest, at process step  134 . At process step  136 , the present invention may highlight the specific motion instructions included within the programmable controller program associated with the robot position, quickly allowing the user or a programmer to review the specific motion instructions associated with a robot position within the programmable controller program. In this way, the program associated with movements of the robot may be quickly reviewed for errors or for potential interference with other manufacturing operations, including with other robots. 
     A flow diagram according to an embodiment of the invention wherein the data indicative of nodes of interest that is captured and stored within hidden robot motion instructions associated with each node of interest may also be used to directly manipulate the robot is shown in  FIG. 6 . In process step  140 , the data indicative of nodes of interest may be accessed by any routine, task, interface module or the like interconnected with the programmable controller  62 , which may further process the data. For example, if the data is stored in hidden robot motion instruction lines in the teach pendant program, any routine, task, interface module or the like may access the teach pendant program. At process step  142 , the stored data is extracted from the storage location. In process step  144 , the stored data is further processed to create a graphical representation of the nodes of interest. In one embodiment, the graphical representation may be displayed on the display  70  associated with the teach pendant  72 . In another embodiment, the graphical representation may be displayed on the user interface  80  of the remote computer  76 . The graphical representation may be in any format, and may show some or all of the nodes of interest and the stored data. In process step  146 , the nodes of interest shown on the graphical representation are associated with the hidden robot motion instructions containing the data indicative of the respective nodes of interest. Thereafter, in process step  148 , the graphical representation is made available to the user, who may utilize the graphical representation in any desirable manner. As a non-limiting example, as shown in step  150 , the graphical representation may include function keys associated with particular nodes of interest. The function keys may be contained inside or outside of the graphical representation, and may further be included on the teach pendant. Actuation of the function key may cause the programmable controller to advance the robot and/or the movable conveyor to a desired node of interest, either in a simulation run or on the robot itself. As noted above, with reference to process step  134  of  FIG. 5 , selection of a function key associated with a node of interest may also highlight a particular motion instruction associated with the chosen node of interest. As a further non-limiting example, within a simulation environment or a testing environment and indicated in process step  152 , a user may be able to point to a node of interest within the graphical representation, e.g. using a mouse click, which will cause the simulation or the actual robot, including any moving conveyor, to read the hidden motion instruction to snap the system, including the robot and the item of work, to the chosen node of interest. As a further non-limiting example indicated in process step  154 , a user may be able to point to a node of interest within the graphical representation to execute the hidden move instruction for that node of interest to snap the system to the chosen node of interest. As still a further non-limiting example, shown in process step  156  and further depicted in  FIGS. 7A and 7B , all data indicative of all nodes of interest captured and stored within hidden robot motion instructions associated with each node of interest may be further processed to create a graphical reachability map  200  of a robotic work cell  210 . 
     The reachability map  200  may graphically depict all or part of a work cell  210  including a robot  212  and a moving conveyor system  214  moving an item of work  216  relative to the robot  212 . The item of work  216  may be shown as a part, a tool, a fixture, or any other item intended to be serviced by the robot  212 . One or more articulating arms  218  may be shown, as required. Within the robotic work cell  210 , accessible areas may be indicated graphically, as shown at reference number  220  on the reachability map  200  in  FIG. 7B . Similarly, non-accessible areas may be graphically depicted, as indicated at reference number  222  on the reachability map  200  in  FIG. 7B . It is understood that accessible areas  220  and non-accessible areas  222  may be graphically depicted in any desirable manner, without limitation. As a non-limiting example, accessible areas  220  may be depicted in one color, e.g. green, while non-accessible areas  222  may be depicted in another color, e.g. red, on the reachability map  200 . In this way, a relatively non-skilled user of the programmable controller may clearly, quickly and easily place a part in the robotic work cell  210  in a desired position. Any additional touch-up or part manipulation by the robot  212  may be easily and quickly visualized and accomplished. A user is able to quickly and easily see where a node of interest is reachable by the system without having to manually move the robot and the item of work to that position. Using the reachability map  200 , the specific move instructions may be reviewed, modified, or tested, and additional move instructions may be easily generated to enhance the productivity of the work cell. And finally, troubleshooting difficulty is minimized because a user may quickly and easily snap the system to a particular node of interest within a simulation, within the actual load cell, or within both. Program review, playback, validation and troubleshooting is simplified because data indicative of nodes of interest is readily available, either as a data object or as a hidden instruction contained within the machine program. Lastly, simulation calibration, tolerance and accuracy may be easily enhanced without troublesome and time consuming manual movement of the robot or the item of interest. 
     While certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes may be made without departing from the scope of the disclosure, which is further described in the following appended claims.