GB2066676A - Measurement and display of impact parameters - Google Patents

Abstract

A golf club head 10 has a cavity 20 to receive an impact-sensing device 21 such as an accelerometer. Electrical connections 22 extend from the device through the hosel 12 and up inside the shaft 13 to a counter element and a display element (not shown). When the golf club strikes a ball, the device 21 senses the impact and transmits this to the counter and display element. An appropriate figure, representing an impact parameter is produced on the display unit for the information of the player. The impact-sensing device may alternatively be located on or within the shaft of the club and may also be used in connection with other impact-delivering sports implements or tools. <IMAGE>

Description

SPECIFICATION Measurement and display of impact parameters This invention relates to means for measurement and visual display of impact parameters. Whilst the present invention will be described hereinafter with particular reference to measurement and display of the impact of a golf-club head on a golf-ball, it is not to be construed as being limited thereto.

It is known from the principle of Conservation of Linear momentum that the momentum (product of mass and velocity) imparted to a ball on impact with a club equals that lost from the club and hence, if the mass of the ball is known, its initial velocity can be determined by observations of the club only. Further application of the laws of mechanics enables the loss of momentum of the club upon impact with the ball to be related to the integral of the deceleration-time function. The momentum transferred during the impact is, by definition, impulse.

A number of methods are known for determining the initial speed of a golf ball, but most of these rely on direct observation of the ball using photographic methods or light beams and photo-electric cells. The former method is impractical because of delays in the processing of the photographs and the latter is difficult to implement in the different circumstances in which a golfer may be practising. Another known method involves some form of "captive" ball and means to measure the velocity imparted thereto. It is also known to determine the speed of the club just before impact with the ball, and photo-electric devices may be used for this also. Yet another known device indicates to the player, by means of an audible click, that his swing has produced a velocity in the club in excess of a predetermined value.

We have now found that an accelerometer may be fitted to the club head, preferably within a recess provided in the head, and an electrical signal proportional to the impact deceleration obtained. By using appropriate electronic devices, this signal may be processed in such a way as to obtain a value for the impulse, which is equivalent to the momentum imparted to the ball. The processed signal may be presented to the golfer in a digital form which could be either an arbitrary "figure of merit" proportional to the imparted momentum or, if the ball is assumed to have a standard mass, the actual initial velocity of the ball.

It is known that, for a golf ball having an initial velocity v, the carry and overall range (carry plus r.un) of the bail can be derived from the following approximate expressions based upon average playing conditions: Carry = 1.5 - 103 Overall range = 1.25 v - 27, where v is measured in ft/sec and the results are expressed in yards. ("The search for the Perfect Swing", COCHRAN and STOBBS).

We have also found that it is possible to house all the required sensing, measuring and display apparatus on or within the club itself, thus providing a readily-portable means for the immediate display of the various impact parameters and avoiding the need for a golfer to be confined to any given area of play.

Accordingly, the present invention provides an impact-delivering implement provided with means for sensing and measuring one or more impact parameters and means for the visual display of those parameters.

In a preferred embodiment, the present invention provides a golf-club comprising a head and a shaft, in which the head contains one or more devices for sensing and measuring the impact of the head on a golf-ball, said devices being connected to a visual display means located on the golf club or within the shaft of the golf club, whereby one or more parameters of the impact are displayed, in a visual manner, to the player.

Several techniques are available to carry out the required computation and since the apparatus is to be built into the club itself rather than contained in a separate unit and attached to the club by cable, low power consumption and potential for miniaturisation are important considerations. One method used in accordance with the present invention employs a voltage-to-frequency converter, fed with a signal from the accelerometer via a buffer amplifier, to generate a train of pulses. These pulses are counted using an electronic digital counter which drives a digital display. The total number of pulses counted during a period of impact is proportional to the impulse and may therefore be used as a measure of ball momentum, or of initial velocity (i.e. the appropriate constant of proportionality is incorporated in the electronic apparatus.

Alternatively, a conditioned signal received from the accelerometer via a buffer-amplifier may be applied to a gated integrator and run-down circuit in order to produce an output signal with a duration proportional to the integral of the input signal. The output signal activates an oscillator, the output from which is counted buy a digital counterwhich in turn drives a digital display. A further function of the gated integrator and run-down circuit is to contain an offset which represents the constant in the equations referred to hereinabove.

One such arrangement according to the present invention uses only three electronic micro-circuits to carry out the computation and drive the display and is small enough to be placed within the grip of a club.

A preferred embodiment of the present invention will be illustrated, merely by way of example, in the following description and with reference to the accompanying drawings.

In the drawings: Figure lisa view, in longitudinal cross-section of a golf-club head, provided, according to the present invention, with impact-sensing means; Figure 2 is an enlarged sectional view of the "circled" portion of Figure 1; Figure 3 is a block-diagram of one form of circuit which can be employed in the device illustrated in Figures 1 and 2; Figure 4 is a block-diagram of a second form of circuit.

Referring to Figure la a golf-club head 10 com- prises a striking-surface 11 and a hosel 12 for the attachment of a shaft 13.

The head is provided with a cavity 20 to receive an impact-sensing device 21. Electrical connections 22 extend from the device 21, through the hosel and up inside the shaft. A screw 23 engages both the club head and the device 21, thereby retaining the said device within the cavity 20.

Alternatively, the device 21 can be attached to the club head by means of an adhesive.

Referring now to Figure 2, the impact-sensing device 21 comprises a base 30 on which there is mounted an annular piezo-electric element 31 and a seismic mass 32. A retaining nut-and-washer assembly (40,40A) and an O-ring 4f engage the device 21 and the club head and retain it within the cavity 20 (see Figure 1).

Electrical contacts 50 and 51 lead to a coaxial cable 22 which extends through the hosel and up inside the shaft to the measuring and display means.

One suitable circuit is illustrated in Figure 3, the display element 27 being mounted on the handle of the golf-club so as to be visible to the player and the remaining elements, viz. buffer amplifier 24, voltage-to-frequency converter 25, counter 26 and batteries 28, being located inside the shaft of the golf-club.

An alternative circuit is illustrated in Figure 4, the display element 66 being mounted on the handle of the golf-club so as to be visible to the player and the remaining elements, viz. buffer amplifier 61, gated integrator and run-down circuit 62, offset 63, oscillator 64, counter 65 and batteries 67, being located inside the shaft of the golf-club.

The golf-club described hereinabove can be used by a golfer in private practice, either on a driving range or using a net. It is possible to incorporate, within the club-head, more than one acceleration transducer arranged to sense rotational and translational impulses and, by using a computer, the direction as well as the speed of take-off of the ball can be calculated. It may also be possible to determine the spin imparted to the ball by measuring tangential impulses. This information, together with a knowledge of the aero-dynamics of a golf ball, would enable the trajectory of a ball to be calculated. Such equipment would be of use to a researcher studying sports ball dynamics and kinematicsorcould form the basis of a side-show event at a golf tournament.

It is to be understood that the present invention is applicable to other forms of impact, for example in sports such as baseball and cricket, and more gener-ally to hammers and other percussion tools.

Claims (6)

1. An impact-delivering implement provided with means for sensing and measuring one or more impact parameters and means for the visual display of said parameters.

2. An implement according to Claim 1, in which the sensing and measuring means includes an accelerometer, a buffer amplifier and a voltage-to frequency converter and the display means includes an electronic digital counter and a digital display.

3. An implement according to Claim 1, in which the sensing and measuring means includes an accelerometer, a buffer amplifier, a gated integrator and a run-down circuit, an offset and an oscillator- and the display means includes an electronic digital counter and a digital display.

4. A golf club comprising a head and a shaft, said club being provided with impact-measuring, sensing and display means according to Claim 1,2 or 3.

5. A golf club according to Claim 4, in which the impact-sensing means comprises an accelerometer attached to the head of the club.

6. A golf club, substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.

6. A golf club according to Claim 4, in which the impact-sensing means comprises an accelerometer placed within a cavity provided in the head of the club.

7. A golf club according to any one of Claims 4, 5 or 6, in which the measuring and display devices are located on or within the shaft of the club.

8. A golf club according to any one of Claims 4 to 7 in which the display means displays a figure corresponding to the distance travelled by a ball on impact with the club.

9. A golf club, substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.

New claims or amendments to claims filed on 16th April 1981.

Superseded claims 1 to 9.

New or amended claims:- 1 to 6.

1. A golf club comprising a head and a shaft, the head being adapted to carry or contain an impactsensing device and the shaft being adapted to carry or contain means for the measurement and display of one or more impact parameters relating to impacts detected by said impact-sensing device, the measurement and display means being wholly carried on or contained within the golf club.

2. A golf club according to Claim 1, in which the impact-sensing device comprises an accelerometer, the measuring means includes a buffer amplifier and a voltage-to-frequency converter and the display means includes an electronic digital counter and a digital display.

3. A golf club according to Claim 1, in which the impact-sensing device comprises an accelerometer, the measuring means includes a buffer amplifier, a gated integrator and a run-down circuit, an offset and an oscillator and the display means includes an electronic digital counter and a digital display.

4. A golf club according to any one of Claims 1 to 3, in which the head is provided with a cavity to contain the im pact-sensing device.

5. A golf club according to any one of Claims 1 to 4 in which the display means displays a figure corresponding to the distance travelled by a ball on impact with the club.