Trace out swimmers performance

Hello.
I am a swimming coach and an electrical engineering student. That is my question: At swimming workouts we (coaches) having hard time to trace out swimmers performance. Now days we have only the stopwatch. Old stop watch is good but it cannot track where the swimmer goes slow – it shows only overall time. I need to track swimmers speed and performance in every moment of the workout. I want to build a self –updating data base that will show me at every moment swimmer name, velocity, distance Inc.

I want to build a sensor with camera (DSP) or any other sensor so I will be able to track my swimmers speeds and distance in any moment in the workout.
Do you guys have any idea what can I start with? What sensors do I need?

Thanks for help

Michael.

You could try a MEMS Accelerometer which has been used in Pedometers for many years. Since the swimmer is going in one direction you can filter the response to show the peak acceleration on the initial forward stroke which will then die down through the stroke before the swimmer applies a new stroke. You could then overlap each stroke on top of one another to see if there is a drop on performance with each stroke. The sensor should be mounted on the Torso or neck away from the feet and legs. The accelerometer might be able to optmise the stroke by seeing alterations in the net acceleration. A good 16-Bit 2g sensor work give you the granuality needed from Freescale or ST (the new ones come in X-Y-Z axis, but all these axis might be able to provide some useful information such as the angular movement of the body which might cause drag).

With all the splashing about with a swimmer you might find that the camera shows very little information except a lot of throth.

Another more elaborate & expensive method (& this is a pure guess) is to use something from the Movie industry when they use people to make CGI movies. The swimmer would need to wear a black diving suit (to hide their IR emissions) and position relatively powerful, very narrow viewing angle (to reduce water dispersion) Infra Red LEDs on the limbs of the swimmer (hands, wrists, elbows, buttocks, back of the knee, and feet). Then position an Infra red camera on the ceiling on a Rail that moves the camera down the pool, while it looks down on the pool. Dim the lights a bit, and then have the Infra red camera follow the swimmer. Hopefully, it might show you the Infra 'dots' from the Infra LEDs mounted on the swimmer. Once you have this information you can create a 'stick man' of the swimmer by joining up the dots. This should tell you if they are swimming incorrectly or they need to change their technique.

The main issue is the water will probably cause the IR light to be become too dispersed, but a good swimmer swims close to the surface, so it might work !

There are companies that already do this for the Movie Industry so rather than reinvent the wheel, you could try one of these, such as Vicon Motion Systems Limited in the United Kingdom.