Thursday, August 9, 2012

The NEW GBD Freedom System!

In the second quarter of 2011, Polhemus announced the release of its latest 3D, 6DOF (degree of freedom) motion capture hardware – the G4. The G4 is a tetherless system in which sensors (the same size as the current ones) are attached by cable to a device the size of a smart phone, typically clipped to the belt. This device transmits (wirelessly) the position and orientation of the sensors to a computer. That is, the golfer will have no “tail” while wearing these sensors!

The obvious advantage to this tetherless system will be the ability to take the system out on the course and the feeling of the golfer that they are less ‘constrained’. A transmitter with power supply will still be required even in this on-course situation, but it does gives greater scope to collect meaningful data under more ‘real-life’ conditions. The sampling rate of 120Hz is less that the Ultimate System (240 Hz) and accuracy is similar at +/- 2 °.

Rob and his programmers are working hard to build the most sophisticated 3D System available in the golf market. How it will be different?

  • It is of course true 3D; that is measuring movement in rotation and translation about 3 axes of motion. K-vest is an example of a 3DOF system – it measures only the rotations about these 3 axes. 
  • We are looking at building three different “models” for the end user, not just one version utilizing three sensors. AMM currently is advertising their version called the Walkabout system which places sensors on the hips, shoulders and club. Our first version of the three sensor model will allow for multiple sensor locations on the body depending on your goal for the teaching session. You get to choose! This is much like our entry level 3D product – the BioFeedback System which utilizes only 3 sensors but has a ‘tail’.
  • We are also taking advantage of a unique feature of the G4 that allows multiple systems to be piggy-backed. Thus, we will have three software versions that allow the use of 3, 6 or 9 active sensors depending on your price point and the degree of sophistication you are after. Thus, the 9 sensor model will be the ‘wireless equivalent’ of our Ultimate System.
Expected price? Well, of course the new hardware is going to be more expensive than that which we currently use (the Liberty Tracker for the Ultimate System). Entry level is expected be around $US10-12 000 compared to our BioFeedback System (Patriot Tracker) at around $7500.

New Software Features!

There are many new additions to the latest version of our software. It constantly evolves so that we can continue to stay ahead of our competitors. At a recent trip to Penn State to demonstrate our product/processes, staff commented that the GBD software was “by far the most advanced software for biofeedback training in golf”.

Most of the features are designed to make the Biofeedback sessions more efficient. Timing and transition graphs can be easily displayed after each swing and tracking the path of the club head is a simple but effective visual feedback tool. There is also great flexibility to display information graphically - you choose the parameter!

Saving time! Another useful addition to latest version of the GBD System software (3.0.0.6 ) is the ability to reload a calibration from file. It can save valuable minutes in a lesson situation. The calibration process provides us with a very accurate anatomical model of each client as seen in the software.

In practice, this allow the operator to reload the last calibration of a client that was completed without the need to re-digitize all the points on the clients body.

This is especially useful if you experience computer issues or a system crash while a client is ‘hooked up’. It saves a lot of time as you no longer need to recalibrate after you restart the software. This new feature is located bottom right in the pointer calibration screen - ‘Reload Calibration From File’ (see screen capture below). Click on this and the system will reload the last digitized points. This should only be used if the client has not been unstrapped from the harness. Not to be used in a new session or if any of the sensors have moved on the golfer.

Lead-arm mechanics - By Rob Neal

In recent years I have been working hard to understand the interaction between the lead arm and the upper torso (UT) during the golf swing and in particular during the transition and downswing portions of the movement. It is one thing to perform the research and understand the mechanics, but quite another to ensure the practical application of such knowledge. It is however, an important step to undertake in order to make such knowledge useful. As a consequence, with the assistance of other teaching professionals, I have been developing a series of coaching drills/exercises to take advantage of this knowledge – the practical application!

The image (left) by Anthony Ravielli from Ben Hogan’s Five Lessons supports what good golf instructors/players have intuitively known for some time. The image appears alongside this excerpt from page 19 of the famous book: “A golfer’s power is originated and generated by the movements of the body. This power is transferred from the player’s body to his arms and then to his hands. It multiplies itself enormously with every transfer, like a chain action in physics” (Ben Hogan and Herbert Warren Wind, 1957).

I have believed for quite some time now that the way in which the Lead Arm and Upper Torso move (that is, the actual shoulder joints!) with respect to one other, is critical in the golf swing. Following some preliminary research, I believe that I identified another stretch-shortening cycle (SSC) that may be as or even more important for the generation/transfer of energy from proximal to distal segments, ultimately leading to high hand and club head speeds. The first one, which is well known in the golf industry, is the X-Factor Stretch or the lead out of the lower body in the transition phase.

After investigating various methods to describe the movements of horizontal flexion-extension as well as flexion-extension of the Lead Arm, the method that I eventually selected is described in brief below. These data are now available as graphs in the latest version of the GBD software.

Shoulder horizontal flexion-extension

The stretch part of the movement occurs between the top of the backswing (TOB) when the minimum horizontal flexion angle between the two segments (arm and UT) is achieved. That is, the arm is squeezed closer to the chest, stretching all the structures on the posterior side of the lead shoulder. The next phase is one of horizontal extension as these posterior muscles contract to accelerate the arm past the UT. The timing sequence graph (below) shows the speed gain from the UT to the arm as a result of this action.

Obviously the graph above depicts a relatively good gain in speed from UT to arm, even if the sequence isn’t perfect (hips peak late). The challenges arise for the teaching professional when working in the practical situation when either the speed gain isn’t present or the actual sequence is not ideal e.g. the arm peaks too early. There are no simple answers of course in coaching, but good coaches know how to prioritize changes for their athletes. And it goes without saying that this issue is virtually impossible to work on without the use of a 3D system.

So, if do we need to change the sequence or the timing for greater efficiency or higher club head speed in our golfer/s, how do we go about eliciting this change? The next step is to determine the causative factor – it is usually a combination of issues relating to swing concept/technique, coordination (motor patterning) and/or physical restraints (muscular inflexibility or lack of strength). The weighting for each can often be teased out using a selection of biofeedback drills and physical screening tests. The subject of another article entirely!

Lead Arm Timing and Co-Ordination Drill

Here is one of the main drills that we use here at the Jim McLean Golf School at Doral to work on training the proper sequence and relationship between the Lead Arm and the Upper Torso - it involves the use of Theraband.

Attach the Theraband to a solid structure at approximately shoulder height. Begin by standing in golf posture holding the Theraband with both hands (this drill can also be completed by holding the Theraband with the left hand only – for right handed golfer) in a position with the arms that would represent the delivery position in the downswing (approximately horizontal to the ground). Then execute the following 4 movements slowly and in sequence:
  1. Shift or bump the hips (laterally) towards the target;
  2. Rotate the hips open;
  3. Rotate the Upper Torso open (this is the point where the lead arm will be squeezed against the chest);
  4. Finally pull down and through with the arms.
German National Team golfer Alex Matlari working indoors with Rob a couple of years ago on this very drill.
Once these 4 movements can be completed independently of one other in the correct sequence, try blending them into a more fluid sequence. The next step – gradually increase the speed of the movement. Then make practice swings holding a club, but without a ball. Then finally add the ball. By controlling the speed of the movement throughout this process, you have a greater chance of correctly executing the new movement pattern. Remember, only the correctly performed repetitions count when it comes to ingraining a new motor pattern. Thus, practicing this coordination drill away from the tee can be very useful, making it easier to ‘pull out’ once the little white ball is placed in front of you.