Abstract:
A positioning system is disclosed. The positioning system has a database for storing a site model. The site model has data indicative of a desired geography of a site environment and an actual geography of the site environment. The positioning system also has a first receiver for generating digital signals representing a real time position in three-dimensional space of at least a portion of a machine as the machine traverses the site environment. The positioning system further has a processor for receiving the signals and updating the site model to determine a difference between the data indicative of the desired geography and the data indicative of the actual geography. The positioning system also has a display for projecting the site model onto at least one surface of an operator station of the machine so that an operator may simultaneously view the site model and the site environment.

Description:
TECHNICAL FIELD  
       [0001]    This disclosure relates generally to a positioning system and, more particularly, to a positioning system for projecting a site model. 
       BACKGROUND  
       [0002]    The construction industry often employs computer systems for digitally mapping work sites, particularly for operations such as earth-moving. To facilitate digital mapping, construction personnel typically provide earth-moving machines with global positioning systems (GPS). As an alternative to employing standard surveying teams, construction personnel use a machine with GPS to produce an initial survey of a work site. The machine with GPS moves back and forth across a worksite, collecting three-dimensional GPS coordinates and providing the data to a computer. The computer, which may be located on board of the machine or located remotely, inputs the data into a software application or algorithm to create a three-dimensional model of the actual contours of the worksite. This model provides the initial survey of the work site. 
         [0003]    Construction personnel also provide input to the computer corresponding to a final desired design plan for the work site. The computer compares the actual terrain contours and the design plan contours to verify the total amount of earth-moving that construction personnel must perform. When operations such as earth-moving begin, a number of machines with GPS may transmit updated GPS information to the computer, which uses the new coordinates to constantly update the actual contours of the terrain map. The computer periodically compares the actual contours to the design plan for the work site. The computer typically provides the terrain map data to construction personnel through a conventional computer monitor display. The computer displays highlighted areas of the work site that need work such as cutting or filling. Construction personnel use the display to verify the progress of construction work such as, for example, earth-moving. Since construction personnel have substantially real time comparison of actual contours to design plans, they can determine if machines are working in the correct locations. 
         [0004]    One shortcoming of the above-described scheme is the difficulty operators have when looking back and forth between the display monitor and the actual worksite visible through the windows of his machine. The display may show a large amount of precise plan lines, which may be difficult for an operator to mentally transpose between the display and the physical changes he is making to the worksite. Additionally, continuously glancing back and forth between the display and the actual worksite for long periods of time may become mentally exhausting and may cause the operator to work less efficiently. 
         [0005]    U.S. Pat. No. 5,751,576 (the &#39;576 patent), issued to Monson, discloses an animated map display method for an agricultural product application. The &#39;576 patent describes an animated map display transposing information related to geological or environmental features, physical structures, sensor signals, status information, and other data for distributing an agricultural product onto a field. The data is displayed as a two- or three-dimensional representation that is projected using a heads-up display (HUD) overlaid onto the real-world terrain and environment visible to the operator through the windshield (or windows) of a machine. The animated map display may present information relating to a particular map set as a three-dimensional image corresponding spatially to real-world terrain or environment, as well as including alphanumeric, pictorial, symbolic, color, or textural indicia relating to navigational, sensor, or other data inputs. The machine carries GPS to provide a coordinate location, and conventional computer processes are used to generate the three-dimensional images. 
         [0006]    Although the method of the &#39;576 patent may provide a method for displaying agricultural information for two-dimensional operations such as agricultural product placement, it may not provide a method for making calculations for three-dimensional operations and displaying the output from those calculations. The method of the &#39;576 patent may not be configured to display three-dimensional design plans associated with construction work. 
         [0007]    The present disclosure is directed to overcoming one or more of the shortcomings set forth above. 
       SUMMARY OF THE DISCLOSURE  
       [0008]    In accordance with one aspect, the present disclosure is directed toward a positioning system. The positioning system includes a database for storing a site model. The site model includes data indicative of a desired geography of a site environment and an actual geography of the site environment. The positioning system also includes a first receiver for generating digital signals representing a real time position in three-dimensional space of at least a portion of a machine as the machine traverses the site environment. The positioning system further includes a processor for receiving the signals and updating the site model to determine a difference between the data indicative of the desired geography and the data indicative of the actual geography. The positioning system also includes a display for projecting the site model onto at least one surface of an operator station of the machine so that an operator may simultaneously view the site model and the site environment. 
         [0009]    According to another aspect, the present disclosure is directed toward a method for providing positioning data to an operator. The method includes storing data indicative of a desired geography of a site environment. The method also includes storing data indicative of an actual geography of the site environment. The method further includes receiving a real time position in three-dimensional space of at least a portion of a machine as the machine traverses the site environment. The method additionally includes updating the data indicative of the actual geography of the site based on the real time position. The method also includes determining a difference between the data indicative of the desired geography and the data indicative of the actual geography in real time. The method further includes updating and storing the difference. The method additionally includes projecting data onto at least one surface of an operator station so that the data indicative of the desired geography, the data indicative of the actual geography, and the difference may be viewed simultaneously with the site environment by an operator. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0010]      FIG. 1  is a diagrammatic illustration of an exemplary disclosed positioning system; 
           [0011]      FIG. 2  is a pictorial illustration of the exemplary disclosed positioning system of  FIG. 1 ; 
           [0012]      FIG. 3  is a pictorial illustration of an exemplary disclosed display; 
           [0013]      FIG. 4  is a pictorial illustration of an exemplary disclosed display; and 
           [0014]      FIG. 5  is a cross-section view of an exemplary disclosed cathode ray tube projector. 
       
    
    
     DETAILED DESCRIPTION  
       [0015]    Referring to  FIG. 1 , a schematic of a three-dimensional positioning system  100  is shown. System  100  may use a differencing algorithm to calculate a machine position and path in real time. System  100  may include a base reference module  40 , a position module  50 , and an update module  60 . Base reference module  40  may be located at a stationary position. Module  40  may be located in a permanent site such as, for example, a building or trailer. Module  40  may be located on a work site  12 , or remotely from a work site  12 . Module  50  and module  60  may be located on a machine such as, for example, a terrain-altering machine  10 . Module  40  and module  50  may together be configured to determine three-dimensional coordinates of terrain-altering machine  10  relative to work site  12 , while an update module  60  may convert these three-dimensional coordinates, e.g., position information, into real time representations of the site, which may be used to monitor and control machine  10 . 
         [0016]    Base reference module  40  may include a stationary GPS receiver  41  for the receipt and processing of GPS signals. Base reference receiver  41  may be a high accuracy kinematic GPS receiver. GPS receiver  41  may include a local reference antenna (not shown) and a satellite antenna (not shown). The satellite antenna may receive signals from global positioning satellites  14  (shown in  FIG. 2 ). GPS receiver  41  may use position signals from the satellite antenna and differential correction signals from the local reference antenna to generate position coordinate data in three-dimensions. Receiver  41  may determine coordinate data within an accuracy of one centimeter. Base reference module  40  may also include a computer  42  for receiving inputs from receiver  41  and reference receiver GPS software  44  that may be temporarily or permanently stored in computer  42 . Base reference module  40  may also include a conventional computer monitor screen  46  and a digital transceiver-type radio  48  or other suitable communications device connected to computer  42  and capable of transmitting a digital data stream. It is contemplated that base reference module  40  may help to verify the GPS location of terrain-altering machine  10  relative to work site  12 . 
         [0017]    Position module  50  may include a kinematic GPS receiver  51 , similar to GPS receiver  41 . Module  50  may also include a matching computer  52  for receiving input from receiver  51  and kinematic GPS software  54  stored permanently or temporarily on computer  52 . Module  50  may further include a standard computer monitor screen  56  and a matching transceiver-type digital radio  58  or other suitable communications device, which receives signals from radio  48  in base reference module  40 . It is contemplated that position module  50  may provide updated GPS data relating to the three-dimensional location of machine  10 . 
         [0018]    Update module  60  may include an additional computer  62  for receiving input from position module  50  and one or more digitized site models  64 , which may be digitally stored or loaded into the memory of computer  62 . Module  60  may also include a dynamic database  66 , also stored or loaded into the memory of computer  62 . The data associated with model  64  and database  66  may describe various states of work site  12 , in three dimensions. Model  64  may include a three-dimensional model of work site  12  as surveyed, as well as the desired three-dimensional plan of work site  12  during various phases of construction or other activity. Model  64  may also include a three-dimensional model of a final design plan for work site  12 . Model  64  may further include updated data from module  50  for constructing a three-dimensional model (updated in real time) reflecting physical changes that machine  10  may make to work site  12 . Therefore, at any given time, model  64  may include a current three-dimensional plan of the site. Computer  62  may contain algorithms that compare the actual state of work site  12  to the desired end state of work site  12  to calculate amounts and locations of work that still must be completed (e.g., cut volumes and fill volumes). Module  60  may further include a display  65 , which may be connected to computer  62 . Display  65  may be a heads-up display, as further described below. It is contemplated that module  60  may maintain an updated three-dimensional model of work site  12  to be used by an operator of machine  10  in completing operations such as, for example, construction work. 
         [0019]    In an exemplary embodiment, some or all portions of update module  60  may be stationed remotely from machine  10 . For example, computer  62 , site model(s)  64 , and dynamic database  66  may be connected by radio data link to position module  50  and display  65 . Position and site update information may then be broadcast to and from machine  10  for display and/or use by operators or supervisors both on and off the machine. It is contemplated that operators may be located in an operator station  16  of machine  10 . 
         [0020]    In an exemplary embodiment, base reference module  40  may be fixed at a point of known three-dimensional coordinates relative to work site  12 . Through GPS receiver  41 , base reference module  40  may receive position information from a GPS satellite constellation, using the reference GPS software  44  to derive an instantaneous error quantity or correction factor. This correction factor is broadcast from module  40  to position module  50  on machine  10  via radio link  48 , 58 . Alternatively, raw position data can be transmitted from base reference module  40  to position module  50  via radio link  48 , 58 , and processed by computer  52 . GPS receiver  41  may be positioned in any suitable manner known in the art such as, for example, on a tripod as illustrated in  FIG. 2 . 
         [0021]    In an exemplary embodiment, GPS receiver  51  may receive position information from the satellite constellation. Kinematic GPS software  54  may combine the signal from GPS receiver  51  and the correction factor from base reference module  40  to determine the position of GPS receiver  51  and machine  10  relative to base reference module  40  and work site  12  within a few centimeters (about an inch). It is contemplated that this position information may be three-dimensional (e.g., latitude, longitude and elevation) and may be available on a point-by-point basis according to a sampling rate of the GPS system. 
         [0022]    Because the sampling rate of position module  50  results in a time/distance delay between position coordinate points as the machine moves over the site, dynamic database  66  may use a differencing algorithm to determine and update in real time the path of machine  10 . Referring to update module  60 , once the digitized plans or models of work site  12  have been loaded into computer  62 , dynamic database  66  may generate signals representative of the difference between actual and desired site terrain to display this difference graphically on display  65 . For example, profile and/or plan views of the actual and desired site models may be combined on display  65  and the elevation difference between their surfaces may be indicated. 
         [0023]    Referring to  FIG. 2 , terrain-altering machine  10  is shown on location at a work site  12 . In the exemplary embodiment of  FIG. 2 , machine  10  may be a track-type tractor which performs earth-moving and contouring operations on work site  12 . Machine  10  may be equipped with hydraulic or electrohydraulic tool controls  24 . Controls  24  may control the actuation of a push arm  26 , tip/pitch cylinders  28 , and lift cylinders  30  to maneuver a tool  32  in three dimensions for desired cut, fill and carry operations. GPS receiver  51  may be located on machine  10  at fixed, known coordinates relative to the site-contacting portions of tracks  17 . GPS receiver  51   a,  similar to GPS receiver  51 , may be located on tool  32  to provide three-dimensional position information of tool  32 . 
         [0024]    As shown in the exemplary embodiments of  FIGS. 3 and 4 , display  65  may be a heads-up display that may be seen by operators as they look out of one or more windshields  18  of operator station  16 . Heads-up display  65  may project information onto windshields  18  without obstructing the view of the operators. Heads-up display  65  may include a cathode ray tube (CRT) projector  67 . CRT projector  67  may be electrically connected to computer  62 , and may receive processed data from model  64  and database  66  via computer  62 . As shown in  FIG. 5 , CRT projector  67  may include a symbol generator  75  capable of processing the data from computer  62  for transformation into pixels or graphics. Symbol generator  75  may be electrically connected to a cathode  68 . Cathode  68  may be any cathode known in the art, suitable for producing a ray of electrons. Based on the data provided by symbol generator  75 , cathode  68  may generate an electron ray  74  that may travel within a glass bulb  69  and strike a glass face  70  of bulb  69 . Face  70  may be coated with phosphors (not shown). As electron ray  74  strikes phosphors on face  70 , the phosphors may give off light, shown as light ray  76 . It is contemplated that display  65  may display some or all of the three-dimensional data maintained by update module  60  to an operator. It is also contemplated that phosphors on face  70  may be configured to give off light of various colors such as, for example, red, green, and blue. 
         [0025]    In an exemplary embodiment, CRT projector  67  may include a focusing coil  71 , which may be located near cathode  68 . Focusing coil  71  may focus ray  74  within bulb  69 . CRT projector  67  may also include deflecting plates  72 . Deflecting plates  72  may direct ray  74  to a given location on face  70 . Depending on the location on face  70  at which ray  74  is directed, light ray  76  may be directed out of CRT projector  67  in a certain direction. The voltage of cathode  68  may also be varied to change the intensity of ray  74 . Computer  62  may include algorithms for controlling the components of CRT projector  67  to produce light rays  76  of a given direction and intensity. 
         [0026]    Display  65  may be a refractive heads-up display, as shown in  FIG. 3 . CRT projector  67  may be mounted within a housing  79 , attached within a recess of a dashboard  80  of operator station  16 . CRT projector  67  may include a collimating lens  73 . Collimating lens  73  may be any suitable lens known in the art for transforming light ray  76  into a set of parallel beams. Windshields  18  may be semi-transparent combining glass, upon which the parallel beams of light ray  76  may be projected. Windshields  18  may also be covered with any suitable semi-transparent coating or film known in the art for enhancing the visibility of projections. Outside light  77  may combine with light ray  76  to form combined light  78 , which may be reflected to the operator&#39;s eyes and allow the operator to view images projected by CRT projector  67  superimposed over the operator&#39;s view of the actual terrain surrounding machine  10 . An advantage inherent in refractive heads-up display  65  may be that the operator may move his head within operator station  16 , while still being able to see the images projected onto windshields  18 . For example, the projected site model may be configured to be viewable at various angles by operators as they change their position within operator station  16 . It is contemplated that light ray  76  and combined light  78  may include light of various colors such as, for example, red, green, and blue. 
         [0027]    CRT projector  67  may project the data, described above, associated with model  64  and database  66  onto windshields  18 . CRT projector  67  may project any desired aspect of model  64 . In an exemplary embodiment, CRT projector  67  may project the desired end state of work site  12 , the actual state of work site  12  (for verification purposes by the operator), or the amount and location of work to be done (based on the calculations comparing the difference between the actual state and end state). It is contemplated that these aspects of model  64  may be color-coded when projected, so that operators may easily distinguish the desired end state, the actual state, and work remaining to be completed. In an exemplary embodiment, aspects of model  64  may be projected in different colors such as, for example, red, green, and blue, by light ray  76  and combined light  78  as described above. Based on the GPS processing defined above, the images may align with the actual terrain visible to the operator outside of operator station  16 . Since windshields  18  may be semi-transparent, the operator may simultaneously view a three-dimensional model of a design plan for work site  12  projected onto windshields  18  and the actual terrain visible beyond windshields  18 , where the projected terrain appears to overlay the actual terrain in the perspective of the operator. 
         [0028]    In a second exemplary embodiment, display  65  may be a reflective heads-up display, as shown in  FIG. 4 . CRT projector  67  may be attached to a mount  81 , where mount  81  may be fastened to a roof  82  of operator station  16 . In the second exemplary embodiment, unlike the first refractive embodiment above, collimating lens  73  may not be integral with projector  67 . Instead, a collimating lens (not shown) may be integral with windshields  18 , where windshields  18  may be curved. Curved windshields  18 , having integrated collimating lenses, may reflect ray  76  in a direction different than received. It is contemplated that curved windshield  18  having the integrated collimating lens may be an off-axis mirror that reflects ray  76  so that combined light  78  is visible to operators only at certain locations within operator station  16  (i.e., when the operator&#39;s head is at certain locations within operator station  16 ). Outside light  77  may combine with light ray  76  to form combined light  78 , which may be reflected to the operator&#39;s eyes and allow the operator to view images projected by CRT projector  67 , similar to the refractive heads-up display described above. 
       INDUSTRIAL APPLICABILITY  
       [0029]    The exemplary disclosed positioning system and associated display may help to provide a method for calculating and displaying a site model to an operator. The disclosed positioning system and display may project the site model onto windshields of an operator station so that operators may compare the projected model with the actual conditions of a work site, allowing them to work more efficiently. 
         [0030]    Machine-mounted GPS receiver  51  may receive position signals from satellites  14  and an error correction signal from GPS receiver  41  via radios  48 , 58  as shown in  FIGS. 1 and 2 . GPS receiver  51  may use the signals from satellites  14  and GPS receiver  41  to accurately determine its position in three-dimensional space. Alternatively, raw position data may be transmitted from GPS receiver  41 , and processed in known fashion by the machine-mounted receiver system to achieve the same result. Using kinematic GPS or other suitable three-dimensional position signals from an external reference, the location of GPS receiver  51  and machine  10  may be accurately determined on a point-by-point basis within a few centimeters as machine  10  moves over work site  12 . The sampling rate for coordinate points using positioning system  100  may be approximately one point per second. 
         [0031]    The coordinates of GPS receiver  41  may be determined in any known fashion, such as GPS positioning or conventional surveying. Work site  12  may be previously surveyed to provide a detailed topographic blueprint (not shown) showing the architect&#39;s finished site plan overlaid on the original site topography in plan view. The creation of geographic or topographic blueprints of sites such as landfills, mines, and work sites with optical surveying and other techniques is a well-known art. For example, reference points may be plotted on a grid over the site and may be connected or filled in to produce the site contours on the blueprint. The detail of the map may increase with the amount of reference points taken. The map may be associated with model  64  and stored within database  66 . 
         [0032]    Systems and software may be currently available to produce digitized, two- or three-dimensional maps of a geographic site. For example, the architect&#39;s blueprint may be converted into three-dimensional digitized models of the original site geography or topography. The site contours may be overlaid with a reference grid of uniform grid elements in known fashion. The digitized site plans may be superimposed, viewed in two- or three- dimensions from various angles (e.g., profile and plan), and/or color coded to designate areas in which the site may need to be machined (e.g., removing earth and/or adding earth). Software may also estimate the quantity of earth required to be machined or moved, make cost estimates, and identify various site features and obstacles above or below ground as is known in the art. 
         [0033]    Computer  52  of position module  50  may provide computer  62  with updated GPS data. Computer  62  may utilize this data in processing algorithms to update data associated with model  64  stored within database  66 . Database  66  may determine the difference between the actual and desired site geographies of model  64  and use the updated GPS data to update and display model  64  in real time with a degree of accuracy measured in centimeters. 
         [0034]    Computer  62  may provide data to symbol generator  75 , allowing symbol generator  75  to control cathode  68 . Cathode  68  may produce ray  74  of electrons, which may be focused by focusing coil  71 . Ray  74  may travel through bulb  69  and be directed by deflecting plates  72  to strike the phosphors located on glass face  70  at a certain location, producing light ray  76 . Light ray  76  may be emitted from CRT projector  67  in a direction corresponding to the location on glass face  70 . Computer  62  may execute algorithms for controlling the components of CRT projector  67  to produce light rays  76  of a given direction and intensity. 
         [0035]    In the refractive heads-up display shown in  FIG. 3 , light ray  76  may pass through collimating lens  73  and be transformed into a set of parallel beams. Light ray  76  may be projected onto windshields  18 . Outside light  77  may combine with light ray  76  to form combined light  78 , which may be reflected to the operator&#39;s eyes and allow the operator to view model  64  as projected by CRT projector  67 . In the reflective heads-up display shown in  FIG. 4 , light ray  76  may be reflected off of curved windshields  18 . Outside light  77  may combine with light ray  76  to form combined light  78 , which may be reflected to the operator&#39;s eyes and allow the operator to view model  64  as projected by CRT projector  67 . Since windshields  18  may be semi-transparent in both the refractive and reflective heads-up displays, the operator may simultaneously view a three-dimensional model of a design plan for work site  12  projected onto windshields  18  and the actual terrain visible beyond windshields  18 , where the projected terrain appears to overlay the actual terrain in the perspective of the operator. 
         [0036]    Three-dimensional positioning system  100  and associated display  65  may help to provide a method for calculating and displaying output describing three-dimensional model  64  to an operator. Display  65  may project output onto windshields  18  of operator station  16  so that operators may immediately compare the projected output with the actual condition of work site  12  without having to look away from windshields  18 . The operators may alter their actions based on the comparison while still looking through windshields  18 , thereby making the work more efficient. 
         [0037]    It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed positioning system and display. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed method and apparatus. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims.