GB1602679A - Apparatus for training golf players - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO APPARATUS FOR TRAINING GOLF PLAYERS (71) We, LEARNING GAMES LIMITED, a British Company of Temple Chambers, Temple Avenue, London E.C.4, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to apparatus for training golf players and is an application for a Patent of Addition to British Patent Application No. 25731/76 Serial No. 1,541,703.The parent application describes and claims in its main claim golf training apparatus comprising a base member having an impact area over which a golfer may swing a golf club to strike a target ball carried in the impact area; a light source arranged to direct light onto the impact area to cause a shadow of the golf club head to fall on the impact area as the club swings across the area a plurality of photoelectric cells distributed in said area so as to receive light from said light source and which may be shadowed monentarily during the passage of the club across the impact area: and signal processing means for correlating signals received from the photocells during the passage of the golf club over the impact area to provide data relating to an impact of the club on the target ball, and wherein said photocells include: first and second photocells located in the path of the club as it swings to pass over the impact area and wherein said processing means includes a counter; a clock pulse generator: and a gate which is enabled when the club passes over said first photocell to allow pulses from said generator to pass to said counter, and which is blocked when the club passes over said second photocell, whereby the number of pulses counted is a function of the speed of the club head.

The present invention is concerned with improvements in golf training apparatus described in the parent application and comprises from a first aspect golf training apparatus as claimed in claim I of specification No. 1,541,703 and including means defining a desired location for a target ball and a pair of linear photosensitive devices for detecting club head direction as it swings to impact the target ball and arranged parallel to one another and to a tangent to a target ball when positioned at said location, each device comprising a photodevice mounted in an enclosure having a slit, whereby the output of the photodevice is proportional to the extent to which the slit is shadowed, the output of said photodevice being taken to a peak detection circuit in turn connected to an analogue-to-digital converter operative to provide a binary number representative of the length of the slit masked.

From a second aspect the -invention consist in apparatus as claimed in claim 1 of specification No. 1,541,703 and including means defining a desired location for a target ball and a pair of parallel linear photosensitive devices or arrays arranged for detecting club head direction as it swings to impact the target ball and wherein the positioning of said linear photosensitive devices or arrays relative to said location is such as to define an ideal path for the swing of the golf club head by being equally spaced on either side of an imaginary line which intersects the tip of the golf club head at the instant the club head impacts the target ball when swung so as to propel the target ball in a direction at right angles to said linear arrays or devices and said imaginary line.

In order that the present invention may be more readily understood, an embodiment thereof will now be described by way of example and with reference to the accompanying drawings, wherein Figure 1 is a perspective view of an embodiment of golf training apparatus constructed in accordance with the present invention, Figure 2 is a plan view of the impact area of Figure 1, Figure 3 shows a photoelectric device, and Figure 4 is a circuit diagram of a dataprocessing circuit.

Referring now to the drawings, the physical form of the mechanical parts of the apparatus is substantially identical to that described in U.K. Patent Specification No.

1,541,703. Thus as shown in Figure 1 a preferred embodiment of the golf training apparatus comprises a strike mat 149 on which a ball 150 is placed in an accurate and specific location. A stand 152 leads to a projector lamp 151 consisting of lamp and condenser lens and this throws a beam down to the ball and creates a sharp shadow of the golf club head used to strike the ball. Under the strike mat in this illuminated zone is an array of photo switches and apertures in the strike mat (not shown in this Figure) which allow the light to penetrate to them. The ball 150 may be a real golf ball but, particularly if the apparatus is set up inside, may be a simulated golf ball as will be described hereinafter.

Mounted on the stand 152 at a convenient height for viewing is a display 155 which reveals the data processed related to the logical deductions from the state of the photo switches in the main beam of the lamp.

The details of display 155 are fully described in specification 1,541,703 and will not be described now.

Figure 2 shows a system of two transverse arrays 56, 57 of photodevices to be partially darkened by a passing golf club shadow so that the relationship as between the number of photodevices darked in the upstream array to those darkened in the downstream array is an indication of golf club direction in the club-ball impact area.

Thus thirteen photo switches 8 to 20 inclusive form Array 56 and thirteen photo switches 21 to 33 inclusive form Array 57. The logical data from the passing club tip shadow falling on these two arrays is used to determine the degree of hooking, slicing or correct straightness of impact direction of a club stroke.

The term 'photo switch' is used to describe two-state photoelectric devices available on the commercial market, but it can be used generally to refer to photocells of appropriate speed and with a following amplifier or device which effectively permits it to be used in a two-state system.

The present application is concerned with the optimum location of the two arrays 56 and 57 for maximum accuracy.

If the downstream array, that is array 57, is located close the point of where the club tip shadow corresponds to the impact between club and ball then the swinging radius of the shadow 5 cuts the upstream array 56 in a different proportion even though at impact the club is travelling in the correct strike direction of straightness.

This error is calculable: Typical distance of radius of club head round the golfers shoulder=62 inches Typical angle of club swing to the vertical=34 degrees Therefore arc of club in the ground plane=62/Sin 34=113 inches Assuming that the club tip shadow Is travelling in the correct straight strike direction through the downstream array then: D2 Error E= 2R 62 2x113 =.16 inches where R is the ground plane radius of 113 inches derived earlier, D is the distance between the two arrays, typically 6 inches.

E is error in inches.

If the photodevices in each array are spaced apart by .2 inches then crossing a connecting line between corresponding photodevices in each array creates a mean directional angle of 2 degrees and thus the error averages .16/2x2=1.6 degrees as 5 of Figure 2.

Such an error is thus appreciable and to correct it the arrays should be arranged as shown in Figure 2 and related to a ball position at 300 so that the two arrays 56, 57 are symmetrically related upstream and downstream about the corresponding club head tip shadow when the club contacts the ball if the club head is travelling in an ideal manner as shown in Figure 2. The impact of the golf club head when swung along an ideal path will propell the target ball at right angles to the linear arrays. In this fashion the errors of the curvature of the club path cancel each other out by symmetry as shown by the path 6.

The output of these two arrays are processed in a manner identical to that described in the specification of the parent application.

However the accuracy of discrimination using digital sensors in two arrays as referred to above is limited by the number of photodevices in each array and with such sensors arranged to define 2 degree increments of off-straight direction the mean deviation is of the order of plus-minus one degree. Ideally there would be an infinite number of sensors in each array and this can be simulated by using two analogue photosensors replacing the two digital arrays. Thus each array may be replaced by a sensor as shown in Figure 3.

Each sensor consists of a hollow box 301 at one end of which is a slit 302 of approximately l/lOth inch wide and of 2 inches length and which permits light to enter the box. In the box there is a photodevice 303 which is sensitive to the admitted light. The box has its internal surfaces of matt white colour which reflects the light admitted in all directions so that there is established a very uniform internal light flux of the sort which prevails in the scientific principle of the hollow white sphere. If one takes a shadow across the admitting slit it is found that the response from the photodevice is substantially linear to the order of about one percent according to the degree to which the slit is shadowed.

The output from the photodevice 303 is arranged in series with a dropping resistor 304 so that the voltage at the point 305 is proportional to the degree of shadowing and this is taken via a diode 306 to a capacitor 307.

The effect of this system is thus to capture the peak voltage corresponding to the peak passing shadow and it is held in the capacitor because of the diode 306. In turn this voltage is taken to a high impedance amplifier 308 where it is converted to a low impedance signal for further manipulation in TTL logic at 309 which is an analogue to digital converter. Thus the output from logic circuit 309 is a number corresponding to the peak shadow falling upon the slit.

The output of the two such systems one upstream and one downstream can then be data-processed in a manner identical to that described in specification No. 1,541,703 where the decoders 61 and 64 provided outputs which were digital numbers corresponding to the number of shadowed photocells. Thus in the present embodiment the two logic circuits 309 will provide binary numbers corresponding to the lengths of the slits 302 shadowed. The subsequent processing of these digita numbers is exactly the same as described in specification No.

1,541,703.

In the specification No. 1,541,703 there is described a separate photodevice for resetting the system on the golf club backswing shadow. An alternative method of resetting the system without using a separate photodevice will now be described.

The two incoming photodevices 1 and 2 which establish the opening and closing of gate controlling clock pulses into a counter for data processing to represent club speed are latched at 38 in the dark state. The output of latched photocell 1 is inverted at 168 and this together with the latched output of photocell 2 are taken to a 2-AND gate 169. Thus this gate 169 will only have a signal output when: a) the upstream speed photodevice I is in the illuminated condition, and b) the downstream speed photodevices 2 is in the darkened condition.

This condition is established if the golfer either places his clubhead in a static state over photocell 2 or if he waggles his club from left to right but stops before darkening photocell 1 i.e. it covers all states relevant to left of the centre line between the two speed photodevices.

The output from the two-AND gates 169 is taken to a 2-OR gate 170 whose other input is fed from a 'full-counter' signal available at 46 of Figure 4.

The full counter signal is generated by either: a) a slow waggle of the club from left to right starting from the mid-point between photocell 1 and photocell 2, or b) a slow waggle of the club from left to right but commencing downstream of photocell 2 and passing over photocell 2 and photocell 1, or c) a slow waggle of the club passing from right to left and passing over photocell 1 and either stopping before photocell 2 or passing over photocell 2.

Thus overall there is an output from the 2 OR gate 170 on any motion of the club head either as to static placing or waggling left or right but which does not create a counter which is only partially full. The output from gate 170 is taken to a 2-AND gate 171 which is also fed from the available clock line at 44. The output from gate 171 thus provides a train of reset pulses under any of the indications described other than a partially filled counter. These pulses replace the original reset system using a separate photodevice and replace line 34 which is described in the parent specification.

Note that the full-counter signal is established when the speed of the club over photocells 1 and 2 in the right to left (striking) direction is so slow (in practice less than 20 ft. per second) that so many clock pulses escape into the counter that it is filled before the clock gate is closed by the darking of photocell 2. It has been found that waggling the club occurs at below this speed so that waggling will establish a full counter and thus reset signals. Only if the club is swung faster than 20 feet per second will the counter only be partially filled corresponding to a true strike.This system has the advantage that it is continuously resetting the system from all preliminary club placings or waggles whereas with the use of a separate reset photodevice such a system can be put into a spurious state by a waggle of unduly large magntiude sufficent to trigger such separate reset photodevice.

The ultimate reset signal required for the strike swing is established by the backswing going over photocell 1 which thus establishes the full counter state and on the ensuing strike swing the system establishes a partial filled counter state which inhibits any further resetting action.

In the parent specification there is described how it is desirable to define a characteristic fault of a golfer on a statistical basis over a number of successive swings.

This can be made automatic by replacing the fault display LEDs by counters which keep adding to the display of a fault of a particular nature as to Hook, Slice, Toe, Heel, Open, Shut, No Faults. All that is needed to effect this improvement is to replace the items 74, 92, 95, 113, 112, 117 described in the parent specification by counters and digital displays each of which is fed by a 2-AND gate whose other input is a pulse indicating that proper swing has taken place. Such a pulse can be triggered into a pulsing unit from the fall to zero of the three-second timing unit 122.

Furthermore the just described feature validating a proper swing can be used to actuate a counter counting the number of swings taken in a successive series and can be numerically displayed by a counterdisplay unit.

But there can also be available from the above features the number of No Faults in a succession of swings.

Strike Efficiency can be defined as equal to l00xNumber of No Faults divided by the number of Swings.

Since the data for the two variables are now available, then the Strike Efficiency can be arithmetically computed by means obvious in the electronic art and the resulting Strike Efficiency can be numerically displayed. After a given series of swings the system can be zeroed by a push-button.

The 'handicap' of a golfer is the number of strokes he takes in a round above the par value for the course which is typically 72 strokes. Since there has been described means for counting the number of No Faults in series of successive golfer's swings and the number of swings then it is obvious in the electronic art also to compute the number of faulty swings by subtraction.

Let the number of swings=S Let the number of faulty swings=F Let P be the par of a golf course over 18 holes Let K be the fraction of a stroke dropped per faulty strike: Therefore total strokes in a round=P( 1 +KF/S) The right hand aspect of the above equation as to PKF/S is the golf handicap.

Since P is typically 72 strokes and since K is typically .5 in that a faulty stroke causes the golfer to lose half a shot then Handicap=72x.5x F/S=36F/S Since the values for F and S are available on counters in the system then the value of 36F/S can be computed in an arithmetic unit and the result displayed numerically.

The golf handicap may be considered as made up of two distinct aspects as to a) corresponding to dropped strokes because of faulty strokes b) corresponding to dropped strokes because of lower yardages then are needed to make the preen in par figures but which are not faults in themselves but may depend upon the age of a golfer.An examination of the par values on golf courses and the hole yardages involved shows that the following strokes will be dropped on average according to the length of the drive and reflecting proportionately as to the yardage from other clubs: Drive Yardage Dropped Strokes Men Women 240 and over 0 230 220 2 210 3 0 200 5 190 6 2 180 8 3 170 11 5 160 14 9 By using the system for measuring drive yardage a golfer can determine his typical yardage and can then dial this into the system on a multipoint switch which has the effect of adding the corresponding handicap numbers as in the above table to those obtained from faulty strikes as determined earlier. Alternatively in determining the drive yardage the successive values in the drive yardage counters can be added together and divided by the number of swings to give automatically the average drive yardage which can be data-processed to give the handicap figures which correspond thereto and thus added into the handicap based on faulty strikes.

A golf training system such as that described herein requires a ball both for the eye of the golfer to focus his attention upon but also to give the corresponding feel at impact as that of a real golf ball used on the golf course. It has been found that light plastic practice balls are defective for use in practising in that they offer no appreciable resistance to the club at impact and thus the speed of the follow through part of the golf swing is much higher than when using a real golf ball. This effect is highly disturbing to a practising golfer since he feels he is being swung off his feet in the follow through. In a normal full golf swing the club head is slowed down by about 30 percent at ball impact and its kinetic energy is reduced by about 50 percent.

The mechanical impedance of a golf ball is due to three factors as to its mass, its stiffness and its dissipative resistance. A practice golf ball equivalent in feel impact to a real golf ball can be devised by making its mass the same as a real golf ball but by giving it low stiffness compared with the high stiffness of a real golf ball and giving it a high resistive dissipation compared with the low resistive dissipation of a real golf ball.

Appropriate materials for such a ball are available from the plastics industry and outstandingly isobutylene-isoprene polymer. This can be weighted with fillers such as sand to have the same weight as a real golf ball and can be moulded either with or without a golf ball cover of standard nature.

In finalising the design of such a practice golf ball as to its exact composition the test is that it must reduce the speed of a golf club at ball impact to the same degree as that of a real golf ball such as by 30 percent when using an 8 ounce headed driving club.

Such a golf ball has the advantage that it does not need a practice net when used indoors and it can be used against a wall and will notappreciably bounce back due to its coefficient of restitution being less than 10 percent.

WHAT WE CLAIM IS: 1. Apparatus as claimed in claim 1 of specification No. 1,541,703 and including means defining a desired location for a target ball and a pair of linear photosensitive devices for detecting club head direction as it swings to impact the target ball and arranged parallel to one another and to a tangent to a target ball when positioned at said location, each device comprising a photodevice mounted in an enclosure having a slit, whereby the output of the photodevice is proportional to the extent to which the slit is shadowed, the output of said photodevice being taken to a peak detection circuit in turn connected to an analogue-to-digital converter operative to provide a binary number representative of the length of the slit masked.

2. Apparatus as claimed in claim 1 of specification No. 1,541,703 and including means defining a desired location for a target ball and a pair of parallel linear photosensitive devices or arrays arranged for detecting club head direction as it swings to impact the target ball and wherein the positioning of said linear photosensitive devices or arrays relative to said location is such as to define an ideal path for the swing of the golf club head by being equally spaced on either side of an imaginary line which intersects the tip of the golf club head at the instant the club head impacts the target ball when swung so as to propel the target ball in a direction at right angles to said linear arrays or devices and said imaginary line.

3. Apparatus as claimed in claim 2, wherein said linear photosensitive devices each comprise a photodevice mounted in an, enclosure having a slit, whereby the output of the photodevice is proportional to the extent to which the slit is shadowed, the output of said photodevice being taken to a peak detection circuit in turn connected to an analogue-to-digital converter operative to provide a binary number representative of the length of the slit masked.

4. Apparatus as claimed in any of the preceding claims wherein the two photodevices used for gating clock pulses for speed detection are combined in logical gates together with a signal from a counter indicating that the golf club is being swung slower than at normal strike speeds, the combination being operative to open a clock gate to provide a train of reset pulses.

5. Apparatus as claimed in any one of the preceding claims in which the various faults or no-fault in successive practice swings are totalised and displayed numerically.

6. Apparatus as claimed in any one of the preceding claims in which the count of No Faults and number of swings is data processed to give their ratio expressed as a Strike Efficiency percentage as hereinbefore defined.

7. Apparatus as claimed in claim 6 and including a manually operable switch adapted to correlate average drive yardage as measured by the apparatus to produce a number which represents the number of strokes which would be dropped in a round of golf in relation to said average drive yardage, the derived number being added to said handicap number.

8. Apparatus as claimed in claim 7, including means whereby drive yardage can be totalised from actual successive swings and averaged, and interpreted into loss of strokes due to short yardage and added to said handicap number.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. of the follow through part of the golf swing is much higher than when using a real golf ball. This effect is highly disturbing to a practising golfer since he feels he is being swung off his feet in the follow through. In a normal full golf swing the club head is slowed down by about 30 percent at ball impact and its kinetic energy is reduced by about 50 percent. The mechanical impedance of a golf ball is due to three factors as to its mass, its stiffness and its dissipative resistance. A practice golf ball equivalent in feel impact to a real golf ball can be devised by making its mass the same as a real golf ball but by giving it low stiffness compared with the high stiffness of a real golf ball and giving it a high resistive dissipation compared with the low resistive dissipation of a real golf ball. Appropriate materials for such a ball are available from the plastics industry and outstandingly isobutylene-isoprene polymer. This can be weighted with fillers such as sand to have the same weight as a real golf ball and can be moulded either with or without a golf ball cover of standard nature. In finalising the design of such a practice golf ball as to its exact composition the test is that it must reduce the speed of a golf club at ball impact to the same degree as that of a real golf ball such as by 30 percent when using an 8 ounce headed driving club. Such a golf ball has the advantage that it does not need a practice net when used indoors and it can be used against a wall and will notappreciably bounce back due to its coefficient of restitution being less than 10 percent. WHAT WE CLAIM IS:

1. Apparatus as claimed in claim 1 of specification No. 1,541,703 and including means defining a desired location for a target ball and a pair of linear photosensitive devices for detecting club head direction as it swings to impact the target ball and arranged parallel to one another and to a tangent to a target ball when positioned at said location, each device comprising a photodevice mounted in an enclosure having a slit, whereby the output of the photodevice is proportional to the extent to which the slit is shadowed, the output of said photodevice being taken to a peak detection circuit in turn connected to an analogue-to-digital converter operative to provide a binary number representative of the length of the slit masked.

2. Apparatus as claimed in claim 1 of specification No. 1,541,703 and including means defining a desired location for a target ball and a pair of parallel linear photosensitive devices or arrays arranged for detecting club head direction as it swings to impact the target ball and wherein the positioning of said linear photosensitive devices or arrays relative to said location is such as to define an ideal path for the swing of the golf club head by being equally spaced on either side of an imaginary line which intersects the tip of the golf club head at the instant the club head impacts the target ball when swung so as to propel the target ball in a direction at right angles to said linear arrays or devices and said imaginary line.

3. Apparatus as claimed in claim 2, wherein said linear photosensitive devices each comprise a photodevice mounted in an, enclosure having a slit, whereby the output of the photodevice is proportional to the extent to which the slit is shadowed, the output of said photodevice being taken to a peak detection circuit in turn connected to an analogue-to-digital converter operative to provide a binary number representative of the length of the slit masked.

4. Apparatus as claimed in any of the preceding claims wherein the two photodevices used for gating clock pulses for speed detection are combined in logical gates together with a signal from a counter indicating that the golf club is being swung slower than at normal strike speeds, the combination being operative to open a clock gate to provide a train of reset pulses.

5. Apparatus as claimed in any one of the preceding claims in which the various faults or no-fault in successive practice swings are totalised and displayed numerically.

6. Apparatus as claimed in any one of the preceding claims in which the count of No Faults and number of swings is data processed to give their ratio expressed as a Strike Efficiency percentage as hereinbefore defined.

7. Apparatus as claimed in claim 6 and including a manually operable switch adapted to correlate average drive yardage as measured by the apparatus to produce a number which represents the number of strokes which would be dropped in a round of golf in relation to said average drive yardage, the derived number being added to said handicap number.

8. Apparatus as claimed in claim 7, including means whereby drive yardage can be totalised from actual successive swings and averaged, and interpreted into loss of strokes due to short yardage and added to said handicap number.

9. Golf training apparatus substantially as

hereinbefore described with reference to the accompanying drawings.