Games using tangible projectile – Golf – Anchored projectile
Reexamination Certificate
2001-03-06
2003-04-22
Nguyen, Kim (Department: 3713)
Games using tangible projectile
Golf
Anchored projectile
C073S065030
Reexamination Certificate
active
06551194
ABSTRACT:
FEDERAL SPONSORSHIP
Not Applicable
MICROFICHE
Not Applicable
BACKGROUND OF THE INVENTION
This invention relates generally to gaming apparatus and more specifically to golf practice apparatus wherein a simulated ball attached to a pivotal support structure is struck.
Golf requires an inordinate amount of practice to become and remain proficient. Outdoor ranges are climate dependent and inconvenient for many, indoor ranges are space limited, and captive ball apparatus currently available does not provide the serious golfer with sufficiently accurate ball trajectory feedback. When striking a captive ball apparatus, the serious golfer wants to know the landing range, trajectory height, and lateral offset of a free ball similarly struck to within about 5 meters/yards (m/yd). Achieving that accuracy requires a three-dimension (3D) initial velocity vector accurate to about 3 mps (10 fps) in magnitude, about 0.5 degrees in azimuth and elevation, and a spin rate around both vertical and horizontal axes to about 100 rpm. Spin about a ball's vertical axis causes horizontal lift and increased drag resulting in a laterally curved flight path and reduced range. Spin about a horizontal axis causes vertical lift, increases drag, and may increase or decrease trajectory height and range. According to U.S. Golf Association (USGA) data as reported in the February, 1999 Golf Digest, pgs 76-79, “Maxing Out Your Ball”, achieving an optimum horizontal axis spin rate of about 2200 rpm versus 3600 rpm typical of most golfers will add 20 to 30 yards (10 to 15 percent) for a ball well struck. Examples of the prior art having germane attributes, as underlined below, to this patent are found in U.S. Pat. Nos. 1,680,897; 3,743,296; 3.815.922; 4,940,236; 5,255,920; and 5,586,940.
U.S. Pat. No. 1,680,897 to Matteson in 1928 discloses a simulated ball mounted on an axle stem within a pivotal structure. Generators driven by the two axles produce current. Current from the pivotal axle is related to ball velocity and generally indicates distance. Current from the stem axle is related to spin rate about a vertical axis and generally indicates a laterally curved ball flight. Azimuth angle, elevation angle, and spin about the horizontal axis are not measured.
U.S. Pat. No. 3,743,296 to Branz in 1973 discloses a simulated ball mounted on an axle stem within a pivotal structure attached to a pivotal yoke. Light cells measure pivotal structure rotation rate (tangential velocity) and generally indicates distance. Cams on the stem axle activate switches to determine spin rate about a vertical axis to generally indicate a hook or slice. Yoke rotation permits the simulated ball to strike one of an array of switches to indicate azimuth. Elevation angle and spin about the horizontal axis are not measured.
U.S. Pat. No. 3,815,922 to Brainard in 1974 discloses a golf ball tethered to a vertical post to which a strain gauge is mounted and about which the ball and tether rotate. The strain gauge measures centripetal force that is related to tangential velocity. Free ball distance is computed from the tangential velocity and some predetermined launch angle. Azimuth angle, elevation angle, and spin are not measured.
U.S. Pat. No. 4,940,236 to Allen in 1990 discloses a transducer (strain gauge) attached to the face of a golf club. The transducer measures the strike force magnitude in a direction generally perpendicular to the face of the club and the duration of the strike event. Means are provided to determine a distance a golf ball would travel when similarly struck by an unaltered golf club at some predetermined launch angle. Azimuth angle, elevation angle, and spin are not measured.
U.S. Pat. No. 5,255,920 to Mangeri in 1993 discloses a golf ball appended to a semi-rigid tether attached to a horizontal axle. A strain gauge equipped flexible disk, in close proximity to the tether, and a slotted disk turn with the axle. When struck, the tether turns the axle and distorts the flexible disk. Light modulated by a slotted disk determines tangential velocity and disk distortion determines azimuth. Distance is computed for a predetermined elevation angle. Elevation angle and spin are not measured.
U.S. Pat. No. 5,586,940 to Dosch, et. al. in 1996 discloses orthogonal load cells (strain gauges) to measure arresting forces of a tethered ball when struck. Means are provided to time integrate 3D arresting forces and determine momentum from which a 3D velocity vector of a free ball so struck is derived. Light sensors are disclosed to determine the face angle of the striking club with means to derive spin rate about a vertical axis of a free ball. These data are used to compute a trajectory of a free ball similarly struck. Spin about the horizontal axis is not measured.
All prior art captive ball golf practice apparatus lack spin rate measurement about a horizontal axis and therefore can have errors exceeding 20 to 30 m/yd, far in excess of 5 m/yd needed by serious golfers. In general, the prior art focuses on measuring preliminary events such as club approach angle, on subsequent events such as the motion or arrest of a captive ball, and on external reactions such as club forces in an effort to reconstruct strike events within the captive ball that cause motion and spin. In doing so, sensor types and their numbers are increased, some components of the strike such as torque cannot be accurately reconstructed, and kinetic energy sinks such as spring compressions and tether extensions must be accommodated; all are error sources, detract from long-term calibration accuracy, and reduce the usefulness of a captive ball practice tee.
BRIEF SUMMARY OF THE INVENTION
Accordingly, the apparatus of this invention focuses on forces and torques within the captive ball that occur during a strike event. The apparatus comprises two separate segments of a simulated golf ball attached to opposing surfaces of a strain plate and a plurality of strain gauges mounted on the strain plate within the ball and on the plate's pivotal support structure. Strains are measured during a strike to the ball to determine a 3D strike force vector, torque components thereof, and strike event duration. Strains caused by centripetal force are also measured after the pivotal structure rotates clear of the striking club and are used to validate strike force measurements and calibration accuracy thereof. The strike force vector and strike duration are used to determine a 3D velocity vector of a free ball similarly struck. Torque content of the strike and strike duration yield both vertical and lateral spin rates. From these data, an accurate 3D trajectory of a free ball similarly struck is computed for display to the golfer.
It is an objective of this invention to:
1. Provide accurate spin rates about both horizontal and vertical axes, as opposed only the vertical axis per the prior art, in addition to a 3D velocity vector so that a trajectory of a free ball similarly struck can be computed with the accuracy needed by the serious golfer.
2. Characterize the actual strike event to minimize potential error sources, rather than attempt to reconstruct it by measuring preliminary events (club face angle, club approach angle, etc) or secondary events (arresting forces, rates of motion, switch activation, etc).
3. Avoid measurement processes that employ kinetic energy sinks (e.g. tethers, springs, friction, etc) that detract from measurement accuracy and long-term calibration accuracy.
4. Provide an apparatus that alerts the user when re-calibration is required.
5. Provide an apparatus that, when struck, produces a familiar impact sensation.
6. Minimize mechanical and electronic part count to make the apparatus affordable.
7. Provide a robust apparatus that is safe and reliable.
How the invention addresses the shortcomings of the prior art and fulfills the requirements for a highly accurate and useful captive ball golf practice tee will become apparent from considering the ensuing description and drawings.
REFERENCES:
patent: 1680897 (1928-08-01), Matteson
patent: 1857588 (193
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