In search of the elusive perfect golf swing

In search of the elusive perfect golf swing, the Kistler 8778A500, one of the smallest and lightest accelerometers commercially available, was ideal for taping onto a golf club head

Even the top, professional golfers find it virtually impossible to find and keep the perfect swing, so what chance the beginner and club player? Both could soon benefit from a device currently being developed by Project Electronics for one of its clients.

Called G-Force, the new device will clip onto the golf club near the head and an LCD readout will indicate to how close the swing was to perfection.

Sounds simple but developing the algorithm to convert a golf swing into a single number has proved to be far from easy.

Project Electronics needed to measure the acceleration throughout the stroke and use this to locate the centre of rotation of the golfer's body.

This involved fixing accelerometers near the head of the club and on the golfer's wrist to produce an acceleration curve that would indicate the "quality" of the swing.

As even novice golfers are sensitive to the weight and balance of the club, it was essential that the accelerometers were not so large and heavy as to influence the swing of the club.

At only 5.74 mm in diameter, 4.3 mm long and weighing 0.4 grams, the Kistler 8778A500, one of the smallest and lightest accelerometers commercially available, was ideal for the job.

Housed in a small plastic holder, the accelerometer could be quickly attached to the club without tools and, more importantly, without damaging the shaft.

To gather the required data, golfers at a local driving range were asked to cooperate.

A representative sample of novice and expert, male and female golfers of different sizes were asked to complete a brief questionnaire before being fitted with the two accelerometers.

The cable from the accelerometer on the club was taped to the shaft and run up the arm of the subject along with the cable from the wrist accelerometer, over the shoulder and to a data logger.

The subject was then asked to drive several times using their normal swing, the whole process taking only 20 minutes.

From the mass of data collected over a whole day, Project Electronics is developing the algorithm to convert the acceleration experienced by the club head into a number indicating the quality of the swing.

When the design is finalised, the G-Force device will be totally self-contained with an accelerometer chip, processing circuits and readout mounted on a small printed circuit board in a plastic moulding that clips onto the club shaft.

Immediately after each stroke, on the course or the driving range, the golfer will be able to see just how good his or her swing really was.

Project Electronics' Technical Director, Meryck Willeard, says, "What initially seemed to be a relatively straightforward consultancy project soon developed onto a complex investigation.

It took the combined resources of both Kistler Instruments and Project Electronics to solve the problem of measuring acceleration at club head and golfer's wrist without the measuring instruments introducing errors.".

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