The ability to to test the efficiency of snowmaking equipment and to characterise ski run conditions precisely depends on the availability of special measuring instruments. Most of the applications are so specialised that we develop the instruments ourselves.
Alongside tests and experiments conducted in the winter sports lab, we also gather numerous measurements taken in the field and along ski runs. We were engaged by the Swiss Olympic Association, for example, to support the country’s athletes by forecasting the snow and weather conditions on the various competition slopes and trails at the 2014 Olympic Winter Games in Sochi. Some of the field instruments are highlighted below.
The Fast Snow Deformer is another instrument (prototype) used to determine snow hardness. Compared to the SnowSpike, it has a much higher rate of loading. The operating principle is similar to that of an impact test – the penetrating element is accelerated by a pre-loaded spring and enters the snow without any additional driving force being applied. The energy consumed when the element penetrates the snow is calculated from the force and travel measurements. The snow can be penetrated at a variety of angles.
Ski-snow interaction
Using the Agenvis measuring device, skis can be tilted at various angles and pressed into the snow while the resistance is measured. The impression made in the snow allows us to establish the penetration depth and ski flex. Instead of penetrating the surface with a ski, a metal plate can be used. The Agenvis device enables us to determine the force-deformation behaviour in a variety of piste conditions. To ensure rigid anchorage of the device, we have developed a special measuring site with locating rails.
To measure the flexural and torsional deformation that occurs during skiing, we have developed a test ski. It is a giant slalom ski with a total of 25 optical fibre (fibre Bragg grating – FBG) sensors fastened in 10 positions. Thanks to the small mass of the FBG sensors and the minimal use of wires (the sensors are connected in series), the ski’s mechanical characteristics remain unchanged. For data recording purposes, the athlete must carry additional weight of around 4 kg. We have fitted another ski with thermocouples. These allow us to record the increase in the temperature of the running surface.
Biomechanics
The pedar®-x foot pressure measuring system by Novel enables us to measure in-shoe plantar pressure distribution using insoles fitted with capacitive pressure sensors. It detects laterality in the motion sequence, among other things, typically of cross-country skiers, as evidenced by their footprint.
Vosskühler HCC-1000 high-speed cameras allow us to capture video sequences with up to 1,850 frames per second. We use these cameras to perform kinematic analyses of motion in sport.
The GNSS Javad Alpha-G3T is a compact, yet high-performance GNSS receiver (GPS & GLONASS). In conjunction with continuous reference measurements, we use it in ski racing for high-precision and highly dynamic kinematic measuring exercises.
Artificial snowmaking
The water supply measuring device records the water pressure, flow rate and temperature prevailing at the supply inlet of snowmaking equipment.
The snowmaking tool is a hand-held device (prototype) for measuring water and air temperature, as well as relative humidity. It calculates the wet-bulb temperature and forecasts the moisture of the snow in an artificially produced snow heap, depending on the environmental conditions and snow lance settings. The snowmaking tool is soon to be made available as a smartphone app.