Map-matching golf navigation system

• US 6,024,655 A
• Filed: 03/31/1997
• Issued: 02/15/2000
• Est. Priority Date: 03/31/1997
• Status: Expired due to Term

• Current Assignee: GPS Industries LLC (Ingersoll Rand, Inc.)
• Original Assignee: Let Leading Edge Technologies Limited
• Inventors: Coffee, John R.
• Primary Examiner(s): Martin-Wallace, Valencia
• Application Number:
  US08/829,678
• Time in Patent Office: 1,051 Days
• Field of Search: 473/407, 473/409, 473/137, 342/457, 342/451, 701/200, 701/207, 701/208, 701/216, 701/224, 701/300, 701/213, 701/214, 701/217
• US Class Current: 473/407
• CPC Class Codes: A63B 2024/0025 Tracking the path or location of one or more users, e.g. players of a game
• CPC Class Codes: A63B 2071/0691 Maps, e.g. yardage maps or electronic maps
• CPC Class Codes: A63B 2102/32 Golf
• CPC Class Codes: A63B 2220/12 Absolute positions, e.g. by using GPS
• CPC Class Codes: A63B 2220/13 Relative positions
• CPC Class Codes: A63B 2220/20 Distances or displacements
• CPC Class Codes: A63B 24/0021 Tracking a path or terminating locations
• CPC Class Codes: A63B 55/61 motorised
• CPC Class Codes: A63B 71/0622 Visual, audio or audio-visual systems for entertaining, instructing or motivating the user
• CPC Class Codes: G01C 21/30 Map- or contour-matching
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial

Abstract

A method for calibrating and updating a golf course position, yardage and measurement system for golf carts that utilize dead reckoning navigation, to avoid gradual buildup of error from components of the dead reckoning system as the golf cart is being driven on the course during play, for the purpose of aiding golfers in playing the course by displaying distance measurements between the golf cart and various course features of interest. In one embodiment, the method includes storing a map of the course golf cart path in the database of the cart navigation system, determining from a comparison of the golf cart position in the dead reckoning navigation system and the stored golf cart path whether the golf cart is on the cart path during at least a part of the play of each hole; and, if so, calibrating and updating the dead reckoning navigation system according to a correction of error in the indicated position of an icon representing the golf cart relative to the cart path on a display screen in the cart to restore the icon to the cart path. In another embodiment, the travel of the cart is compared to the meanderings of the cart path on the stored map by comparing the dead reckoning trajectory of the cart to sequences of segments along the cart path until a pathway trajectory is found that closely matches the trajectory of the golf cart; and then correcting the indicated position of the golf cart accordingly, by which to calibrate and update the dead reckoning navigation system.

Claims

1. A method for obtaining accurate measurements of distance of a golf cart equipped with a computerized dead reckoning navigation (DRN) system from features of interest on a hole of a golf course including tee boxes, cups, water hazards, sand traps, rough areas adjacent fairway, and cart path, to assist golfers in playing the hole, wherein the golf course has been surveyed so that fixed positions of at least some of said features including the cart path are known and are part of a map of the course stored in the data base of the computerized DRN system, the DRN system having a capability to detect and indicate the position of said golf cart on the course map but undergoing a gradual increase in error of indicated position of the golf cart as the cart is driven about the course during play, thereby introducing error buildup into each said measurement of distance of the cart to said features, said method comprising the steps of:

examining by means of the DRN system whether the golf cart is on or off the cart path during at least part of the time that said cart is in use in play of each hole; and

at a point in time when the cart is determined to be on the cart path during said play, calibrating the DRN system, including Kalman filter processing information derived in said DRN system from driving said cart, to substantially eliminate the built up error and thereby restore accuracy of measurements performed by the DRN system at that point in time by substantially reducing the discrepancy between (a) a point on the cart path determined to be the actual approximate position of the golf cart and (b) the indicated position of the golf cart removed from said point on the cart path.

2. A method for obtaining accurate measurements of distance of a golf cart equipped with a computerized dead reckoning navigation (DRN) system from features of interest on a hole of a golf course including tee boxes, cups, water hazards, sand traps, rough areas adjacent fairway, and cart path, to assist golfers in playing the hole, wherein the golf course has been surveyed so that fixed positions of at least some of said features including the cart path are known and are part of a map of the course stored in the data base of the computerized DRN system, the DRN system having a capability to detect and indicate the position of said golf cart on the course map by virtue of including at least one wheel sensor on the golf cart from which to encode wheel rotations and thereby determine position and speed of the golf cart and a compass for determining magnetic heading of the golf cart, but said DRN system undergoing a gradual increase in error of indicated position of the golf cart as the cart is driven about the course during play, thereby introducing error buildup into each said measurement of distance of the cart to said features with contribution thereto from each of said wheel sensor and said compass, said method comprising the steps of:

examining by means of the DRN system whether the golf cart is on or off the cart path during at least part of the time that said cart is in use in play of each hole; and

at a point in time when the cart is determined to be on the cart path during said play, calibrating the DRN system, including Kalman filter processing information derived in said DRN system from driving said cart, to substantially eliminate the built up error and thereby restore accuracy of measurements performed by the DRN system at that point in time by substantially reducing the discrepancy between (a) a point on the cart path determined to be the actual approximate position of the golf cart and (b) the indicated position of the golf cart removed from said point on the cart path.

3. A method for obtaining accurate measurements of distance of a golf cart equipped with a computerized navigation system from features of interest on a hole of a golf course including tee boxes, cups, water hazards, sand traps, rough areas adjacent fairway, and cart path, to assist golfers in playing the hole, wherein the golf course has been surveyed so that fixed positions of at least some of said features including the cart path are known and are part of a map of the course stored in the data base of the computerized navigation system, the navigation system having a capability to detect and indicate the position of said golf cart on the course map but undergoing a gradual increase in error of indicated position of the golf cart as the cart is driven about the course during play, thereby introducing error buildup into each said measurement of distance of the cart to said features, said method comprising the steps of:

examining by means of the navigation system whether the golf cart is on or off the cart path during at least part of the time that said cart is in use in play of each hole, including establishing search zones overlying a sequence of respective generally straight line sections of the cart path in a portion of the stored map of the golf course on a display screen in the golf cart, and identifying one of said zones as being the most likely real time location of the golf cart, said search zones being established as substantially rectangular with side boundaries generally parallel to the section of the path within the respective zone and constituting predetermined limits that define the cart as being off path whenever an icon representative of the cart on the display screen is outside said limits; and

at a point in time when the cart is determined to be on the cart path during said play, calibrating the navigation system, including searching successive segments of the cart path in said identified zone to determine the specific segment on which said point on the cart path lies and moving the indicated position of the cart to said point on the cart path, to substantially eliminate the built up error and thereby restore accuracy of measurements performed by the navigation system at that point in time by substantially reducing the discrepancy between (a) a point on the cart path determined to be the actual approximate position of the golf cart and (b) the indicated position of the golf cart removed from said point on the cart path.

4. A method for obtaining accurate measurements of distance of a golf cart equipped with a computerized navigation system from features of interest on a hole of a golf course including tee boxes, cups, water hazards, sand traps, rough areas adjacent fairway, and cart path, to assist golfers in playing the hole, wherein the golf course has been surveyed so that fixed positions of at least some of said features including the cart path are known and are part of a map of the course stored in the data base of the computerized navigation system, the navigation system having a capability to detect and indicate the position of said golf cart on the course map but undergoing a gradual increase in error of indicated position of the golf cart as the cart is driven about the course during play, thereby introducing error buildup into each said measurement of distance of the cart to said features, said method comprising the steps of:

examining by means of the navigation system whether the golf cart is on or off the cart path during at least part of the time that said cart is in use in play of each hole; and

at a point in time when the cart is determined to be on the cart path during said play, calibrating the navigation system including searching the data base of cart path segments to locate the segment closest to the indicated position of the golf cart, to substantially eliminate the built up error and thereby restore accuracy of measurements performed by the navigation system at that point in time by substantially reducing the discrepancy between (a) a point on the cart path determined to be the actual approximate position of the golf cart and (b) the indicated position of the golf cart removed from said point on the cart path;

said searching including;

starting the search at a section of the cart path on which the golf cart was last indicated to be positioned on the measurement system, and thereafter first searching said section for a segment thereof which lies substantially parallel to the direction of travel of the cart, including;

searching forward and backward along said section and testing cart path segments there of for substantially the same vector direction as the heading of the golf cart within limits determined by the estimated extent of compass errors and map errors, and

if a substantial match of vector direction of a segment and heading of the golf cart is found in the course of the search, verifying that the indicated position of the golf cart lies between imaginary lines extending normal to the cart path segment for which said match was found, at the endpoints of said segment, and if multiple segments are found with said substantial match, selecting that one of the multiple segments which lies closest to and within a predetermined distance limit from said indicated position of the golf cart, or,

if no match is found, or if it is determined that the golf cart has not been on a cart path recently, establishing substantially rectangular search zones overlying the stored map of the golf course, with at least some of the search zones overlapping each other, and searching the cart path segments in only the zone which encompasses the cart'"'"'s indicated position.

5. The method of claim 4, including searching the cart path segments in multiple zones if the indicated cart position lies in an area where said multiple zones overlap one another.

6. A method of calibrating a golf cart navigation system used to compute and display position of the cart and relative real time distance from the cart to selected features of a golf course on which the cart is used, said method comprising:

storing a map of the cart path for said golf course in the data base of the navigation system; and

periodically correcting the position of the cart on the golf course as indicated by the navigation system, from a comparison between selected parameters of the indicated cart position and selected parameters of the stored course map, for use in calibrating the navigation system according, at least in part, to the actual real time position of the cart on said course, wherein said comparison is performed by

establishing an overlay of substantially rectangular search zones along successive sections of the cart path for a portion of the course of interest on the stored map in the navigation system, and

searching within selected ones of the zones for a cart path segment having a direction and location which are closest to the real time heading and position of the cart, and after said segment is found, verifying that the indicated position of the cart lies within endpoint boundaries established for that segment of the cart path.

7. A method of calibrating a golf cart navigation system used to compute and display position of the cart and relative real time distance from the cart to selected features of a golf course on which the cart is used, said method comprising:

storing a map of the cart path for said golf course in the data base of the navigation system; and

periodically correcting the position of the cart on the golf course as indicated by the navigation system, from a comparison between selected parameters of the indicated cart position and selected parameters of the stored course map, for use in calibrating the navigation system according, at least in part, to the actual real time position of the cart on said course;

said method further including a global positioning satellite (GPS) calibration system, and said comparison constituting a map-matching or map-correlation technique employed as an alternative to the GPS calibration system at least occasionally when the cart is restricted to the cart path.