Professional Swiss skiers, once among the best in the world, have not been on top form for several years. This low point in the sport worried student Erich Crameri, who, with his ETH work in mind, felt that Switzerland could be helped out of the ski doldrums and back onto the winner’s podium using technical aids. Via “wearable computing”, a portable sensory system coupled with electronic evaluation technology, he was convinced that skiers’ style could be analysed and their techniques improved. Together with his supervisor Florian Michahelles (at the time of the study part of Professor Bernt Schiele’s research team at the Department of Computer Science) Erich Crameri got to work on developing it. (1)

Skiing with a laptop

The system has various components. In the skier’s boots, for instance, the scientists installed pressure sensors able to withstand up to 85 percent ambient humidity. A sensor was fitted to the outside of the boot which measured the distance to the ground, allowing the team to calculate the leaning angle of the ski. In addition, they attached a gyroscope to the bindings, which provided information on ski rotation. Two further sensors, one on the lower leg and one on the upper torso, registered acceleration. The first, explains Michahelles, was mainly to identify vibrations and the second captured the skier’s overall movements. Finally, the team also investigated the possibility of measuring a skier’s speed using a radar unit fixed to the front of the ski. All sensors were connected via wires to a central laptop in the skier’s backpack. In a later phase (in a semester assignment for Franco Hug), the laptop was replaced by a small recording device, which stored the data on a chip in much the same way as a digital camera.

The system, however, was still incomplete, because the collected data now had to correspond to an actual swish down the slopes. Student Frederic Despont, again in the context of a semester assignment, created a piece of software aptly called SKI. This application set out all the sensors’ data and synchronised it with video recordings of the corresponding run. With the electronic preparations complete, the first test run was undertaken on the piste above Zermatt. After thirty minutes of wire fitting, Erich Crameri made the first perhaps best-ever scrutinized ski turns. A preliminary analysis showed that the system, apart from the radar component, worked.

The software package “SKI” makes it possible to correlate the collected data. How it looks on the screen. large

Ready for a “measured” ski run, ETH student Erich Crameri, fitted out with sensors and a laptop in his backpack. (Photo: Florian Michahelles) large

Frehsner likes it

To test the level of interest in their system among professional athletes, the team presented their recordings and apparatus to four ski experts, among them the Austrian Karl Frehsner, who has also served Switzerland in many capacities. These felt that measuring the distance to the ground provided the most valuable information,as this makes it possible to determine whether a ski is rotating too early or too late. They found the system so interesting, in fact, that the Swiss Junior Team was allowed to use it. For “wearable computing” to be deployed on a large scale, however, the experts say that the equipment design would have to be somewhat more manageable, the radar would have to work, and there should be a gyroscope on the torso of the skier to measure turning movements. A sensor around the hips to measure acceleration would also be very useful.

My trainer, the computer

Florian Michahelles is aware that the prototype is not yet ready for practical application. Even though he now has a new ETH job and the project is temporarily on ice, he believes that it would be an easy matter to improve the system. He would, for example, increase the tact rates of the sensors and use wireless signals instead of wires; and it is possible that data could be transferred to a trainer’s palm-held computer or similar after each run. Further along the line, Michahelles thinks it likely that all skiers could benefit from the system: instead of a bronzed ski instructor, a touchy-feely computer could help them improve their technique on the piste. Like the pulse-meter helps joggers, so could a portable computer benefit skiers.

For the time being, however, this dream remains at the prototype stage. Before it becomes reality, several crashes, of both the ski and the computer variety, will have to be weathered.