Patent Publication Number: US-2010114373-A1

Title: Systems and methods for scanning a workspace volume for objects

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional patent application Ser. No. 61/110,374 filed Oct. 31, 2008, the entirety of which application is expressly incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure is generally related to robotic machines and, more particularly, is related to robotic machines that handle heavy payloads over long distances. 
     BACKGROUND 
     It has become more and more common to consider work areas that are shared by people and robots. As such, accidents between the robots and people may also increase. The robotic machines are typically designed to have provisions for separate but changing volumes for the robotic arm and operators. The direction is toward smaller volumes for the robotic machines relative to the operators. The industry has moved from rather large stationary volumes that are entered by the people with the robotic machine off to moving volumes surrounding the moving parts of the robotic machine with people still within the possible range of the motion of the robotic machine. This allows people to enter a volume that has previously been used by the robotic machine and vice versa. 
     Generally after any stop, an operator verifies that a work area is free of any person and then pushes a resume “button” or device to resume operation of the robotic machine. This approach has the shortcoming of depending on manual verification, itself not as reliable it might seem, and furthermore causing a delay. 
     Desirable in the art is an improved robotic machine that reduces physical injuries, particularly serious injuries, as a result of accidents caused by the contact of a person with the robotic machine. 
     SUMMARY 
     A representative robotic machine includes an end-of-arm; and a safety scanner system that scans for objects in a workspace volume around the end-of-arm. The safety scanner system determines whether to stop operations of the robotic machine based on the presence of the objects in the workspace volume. 
     Other systems, devices, methods, features of the invention will be or will become apparent to one skilled in the art upon examination of the following figures and detailed description. It is intended that all such systems, devices, methods, features be included within the scope of the invention, and be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, the reference numerals designate corresponding parts throughout the several views. While several embodiments are described in connection with these drawings, there is no intent to limit the disclosure to the embodiment or embodiments disclosed herein. On the contrary, the intent is to cover all alternatives, modifications, and equivalents. 
         FIG. 1  is a perspective view of an exemplary robotic machine that includes an overhead rail mounted machine in accordance with an embodiment of the present disclosure. 
         FIG. 2  is a top view that illustrates a work area having a scanned area generated from a robotic machine in accordance with an embodiment of the present disclosure. 
         FIG. 3  illustrates a safety scanner system implemented on an overhead rail mounted machine in accordance with an embodiment of the present disclosure. 
         FIG. 4  is a flow diagram that illustrates an embodiment of the architecture, functionality, and/or operation of a safety scanner system in accordance with an implementation of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary systems are first discussed with reference to the figures. Although these systems are described in detail, they are provided for purposes of illustration only and various modifications are feasible. After the exemplary systems are described, examples of flow diagrams of the systems are provided to explain the manner in which a work area is scanned for objects. 
     This disclosure addresses the issue of scanning a workspace volume, e.g., the area around the end-of-arm of the robotic machine, to assure that no person is present in a work area. Before scanning, a first provides an obstacle free conventional boundary of the work area, typically optical in nature. In either case, a boundary around the robotic machine is provided into which persons or other unexpected items should not intrude. 
     This disclosure is related to mechanisms that make robotic machines more safe with an emphasis on reducing any damage to persons and equipment because of the robotic motion. The damage reduction is achieved by detection of persons or things near a payload. A mechanism, among others, for achieving this is to detect that people are not near an end-of-arm (BOA) of the robotic machines even when people may be within the possible workspace of the BOA. 
     The robotic machines described in this disclosure generally handle heavy payloads over long distances. However all of the described mechanism can be applied to many robotic situations and many machines used in moving material automatically or with mechanical assistance. The robotic machines utilize technologies related to position estimation, learned control effort, and command shaping that can allow the construction of lightweight, imprecise machines to achieve high-speed, accurate motion. Such technologies have been disclosed in U.S. Pat. Nos. 5,946,449, to Dickerson, et al. and 6,078,844, to Magee, et al., the entirety of which applications are expressly incorporated by reference herein. 
     The fabrication of the robotic machine can take a wide variety of forms.  FIG. 1  is a perspective view of an exemplary robotic machine  100  that includes an overhead rail mounted machine in accordance with an embodiment of the present disclosure, In this example, an end-of-arm (BOA)  130  of the robotic machine  100  generally extends from the ceiling to the ground and can cause injury to people. The robotic machine  100  can be designed to move payloads held at the end-of-a n (BOA)  130  from place to place in a fast, reliable, accurate, and safe manner. 
     X rails  105  are placed parallel to each other and are generally attached to a top structure (not shown), such as, a ceiling beam. A Y bridge  110  is coupled to the bottom of the X rails  105 , generally at the ends of the Y bridge  110 . The Y bridge  110  is positioned substantially perpendicular to the X rails  105 . A control module  125  is placed on top of the Y bridge  110 . The control module  125  includes a computing device, motors, and sensors, among others, that can facilitate moving the Y bridge  110  along the X rails  105  in the X direction. The Y bridge  110  is coupled to a Z beam  120 , which roves along the Y bridge  110  in the Y direction. 
     The Z beam  120  can move up and down in the Z direction. The Z beam  120  includes a proximal and  135  and distal and  140  in which the distal end  140  is coupled to a mounting plate  145 . The mounting plate  145  can include, but is not limited to, tooling devices and gripping devices. The distal end  140  of the Z beam  120  is generally referred to the end-of-arm (EOA)  130 . 
       FIG. 2  illustrates a work area  205  that includes a scanned area  210  generated from a robotic machine  100  in accordance with an embodiment of the present disclosure. The Z beam  120  includes the BOA  130  that can move along the Y bridge  110  in the Y direction  220 . A scanned workspace volume around the robotic machine  100  includes a mechanism that detects people entering the scanned area  210 . The scanned area  210  may move with the robotic machine  100  or robot EOA  130 . A person penetrating the scanned area  210  can cause a controlled stop, halting operations of the robotic machine  100 . 
     Current technology for example scanners by SICK inc. and others are capable of safety rated scans every 60 ins at distances up to 7 meters. The later measurement type is assumed here to be used at 0.25 degree steps in distance and take 53 ms total scan time for 180 degree scans. The scanned workspace volume moves around the work area  205  as scanners move with the EOA  130 . For example, the initial scanned workspace volume may be positioned in a location of the work area  205  that a person may not be within. As the EOA  130  moves to another location of the work area  205 , the scanned workspace volume also moves with the EOA  130  and may now be in the area that a person is operating the robotic machine  100 . 
     Scanners  305 ,  310  ( FIG. 3 ) can be used to scan from the Y bridge  110  out towards the boundaries of the scanned area  210  to vent S&#39; a person is not present before lowering the robot gripper or EOA  130  into a robotic work space (not shown). The scanners  305 ,  310  scans a broad width in the Y direction  220  and each moves from the Y bridge  110  to the outside of the scanned area  210 , that is in −/+f-X direction  235 ,  240  to check of the area is clear of people. This permits scanning of a large volume over a period generally of one or more seconds. More scanners  305 ,  310  can be utilized to scan in the −/+Y directions  245 ,  250  in order to establish a complete rectangle of the scanned area  210 . 
     Note that once the scanners  305 ,  310  are in the out position and no person has been found the robotic machine can start operations and the scanners remain in the out position. Note also that the concept can be generalized to have moveable scanners in both the X and Y directions  225 ,  220  so that the rectangular box of protection can be moveable in two directions. 
       FIG. 3  illustrates a safety scanner system  300  implemented on an overhead rail mounted machine  100  in accordance with an embodiment of the present disclosure. The safety scanner system  300  includes scanners  305 ,  310  that can be coupled to the control module  125  ( FIG. 1 ), which includes a scanner software (not shown) having instructions for controlling the scanners  305 ,  310 . The scanners  305 ,  310  scan a range in the X direction  225  and the moves from the middle to the outside (bottom) in the X direction  225 . Note that this permits scanning of a large volume over a period generally of one or more seconds. Alternatively or additionally, the scanners  305 ,  310  can have vertical patterns and move mechanically outward in the X direction  220  when scanning rather than having rotating planes of beams. The safety scanner system  300  can scan for the objects in the workspace volume by moving planes of laser beams with, for example, a servo or other motion device. The safety scanner system  300  can determine the workspace volume above the work area  205  by using, for example, three or more planes of the laser beams 
       FIG. 4  is a flow diagram that illustrates an embodiment of the architecture, functionality, and/or operation of a safety scanner system  300  in accordance with an implementation of the present disclosure. In block  401 , the safety scanner system  300  determines a work area  205  of the robotic machine  100 . In block  405 , the safety scanner system  300  scans the work area  205  in advance of the positions of objects  315 ,  320 ,  330 ,  335  ( FIG. 3 ) in the work area  205  so that the workspace volume effectively is safe for people  325  (or other objects not expected in the work area  205 ). For example, the safety scanner system  300  scans the workspace volume around the EOA  130  at multiple locations in the work area  205  until the entire work area  205  is scanned for, e.g., stationary or expected objects. The stationary or expected objects  315 ,  320 ,  330 ,  335  in the work area  205  should not be detected as people. The objects  315 ,  320 ,  330 ,  335  include, but are not limited to, boxes, pallets, plants, desk, chairs, tool boxes, and a desktop, among others. To overcome the difficulty of determining whether people are in the work area  205 , a pre-scan can be made when no person is present and no unexpected objects are present. 
     In block  410 , the safety scanner system  300  learns the pre-existing location and profiles in the X, V, and Z directions of the objects  315 ,  320 ,  330 ,  335 . In block  415 , the safety scanner system  300  scans for the presence of people in a volume around the, e.g., EOA  125 , before enabling the robotic machine to operate. In block  420 , the safety scanner system  300  can halt operation of the robotic machine  100  responsive to detecting a person in the workspace volumen. The scanning for the presence of people can be accomplished by way of imaging based on range, which can be described as range imaging. The current state of the art suggests that cameras will soon be able to do a very similar function. 
     The scanning process determines the locations of objects  315 ,  320 ,  330 ,  335  and scan for people such that the scanner system  300  is not fooled by the objects  315 ,  320 ,  330 ,  335 . This learned pattern would be created relatively infrequently. The ability of robots to know the locations of the objects  315 ,  320 ,  330 ,  335 , as described in connection with blocks  405  and  410 , would be used to allow the scanning for people to be done properly 
     Range imaging was previously described to detect people in the work area  205 . Range imaging can utilize a vision-based system that uses multiple cameras to detect anything visible within a set of programmable volumes on the basis of triangulation. A sensor head of the vision-based system can move to facilitate detecting objects in the work area  205 . 
     Other sensors can be used to reliably find people or other objects within the work area  205 . The sensors can distinguish people from objects  315 ,  320 ,  330 ,  335 . Some alternatives are described are follows:
         Infrared cameras are a way of detecting people as “hot spots”. However, it is not clear how well these would do, particularly in the summer if the temperature of natural objects goes near 90 degrees.   Acoustic range sensors are relatively cheap and light and could be in an array in the secondary enclosure. Unfortunately people are not very good targets for such sensors as the acoustic reflection is unreliable. Further beam spreads tend to be large.       

     Radio beacons can be used to track all objects, such as people, if the radio beacons are attached to the objects. The objection to this is reliability as it requires that people wear the devices and maintain a good position relative to RF reflective surfaces, typically metals or other conductors. 
     The systems and methods disclosed herein can be implemented in software, hardware, or a combination thereof. In some embodiments, the system and/or method is implemented in software that is stored in a memory and that is executed by a suitable microprocessor (μP) situated in a computing device. However, the systems and methods can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device. Such instruction execution systems include any computer-based system, processor-containing system, or other system that can fetch and execute the instructions from the instruction execution system. In the context of this disclosure, a “computer-readable medium” can be any means that can contain, store, communicate, propagate, or transport the program for use by, or in connection with, the instruction execution system. The computer readable medium can be, for example, but not limited to, a system or propagation medium that is based on electronic, magnetic, optical, electromagnetic, infrared, or semiconductor technology. 
     Specific examples of a computer-readable medium using electronic technology would include (but are not limited to) the following: an electrical connection (electronic) having one or more wires; a random access memory (RAM); a read-only memory (ROM); an erasable programmable read-only memory (EPROM or Flash memory). A specific example using magnetic technology includes (but is not limited to) a portable computer diskette. Specific examples using optical technology include (but are not limited to) optical fiber and compact disc read-only memory (CD-ROM). 
     Note that the computer-readable medium could even be paper or another suitable medium on which the program is printed. Using such a medium, the program can be electronically captured (using, for instance, optical scanning of the paper or other medium), compiled, interpreted or otherwise processed in a suitable manner, and then stored in a computer memory. In addition, the scope of the certain embodiments of the present disclosure includes embodying the functionality of the preferred embodiments of the present disclosure in logic embodied in hardware or software-configured mediums. 
     It should be noted that any process descriptions or blocks in flowcharts should be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps in the process. As would be understood by those of ordinary skill in the art of the software development, alternate embodiments are also included within the scope of the disclosure. In these alternate embodiments, functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved. 
     This description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments discussed, however, were chosen to illustrate the principles of the disclosure, and its practical application. The disclosure is thus intended to enable one of ordinary skill in the art to use the disclosure, in various embodiments and with various modifications, as are suited to the particular use contemplated. All such modifications and variation are within the scope of this disclosure, as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly and legally entitled.