Super sliders: how load cells help skeleton athletes go faster

If like us you have been glued to the Winter Olympics from South Korea, you can’t have helped but notice the excellent results gained by the TeamGB skeleton team.

Skeleton speed

Frankly, we’re amazed anyone considers hurting down a twisting tube of concrete coated in ice on a sled the size of a tea tray to be fun. However, the science behind skeleton sleds and bobsleighs can give athletes that crucial 2/100 of a second difference down a run, often the margin between a medal and nothing.

For the Vancouver Winter Olympic games, the US skeleton team employed the expertise of Rensselaer Polytechnic Institute (RPI) to help the team combat the single biggest factor in improving their timings: wind resistance.

 

Crucial factors for skeleton success

The final speed of an athlete down the track is determined by three factors:

• Wind resistance
• Keeping the sled straight to avoid friction on the ice
• The athlete sliding the shortest line down the track

The team at RPI built a complete section of bobsleigh track, measuring half a metre deep and one metre wide. They then placed a sled measuring 20cms wide and 120 long on pads containing load cells, to measure the downward force exerted by the slider (athlete), and augmented that with feeds from two cameras. In addition, the track section was positioned at the ned of a wind tunnel blowing air at almost 100kms per hour.

 

Looks like a drag

As Engineering professor Timothy Wei explained in an article for Scientific American:

“The athlete can see in real time the affect of their movement on airflow and drag. You know the forces, but you’d also like to know what the flow looks like.”

 

British bobsleigh bonus

The British two-woman bobsleigh duo of Mica McNeill and Mica Moore came a highly respectable 8th place in this year’s finals. Their achievement is all the more remarkable in that the duo’s funding was withdrawn in 2017, and they only managed to come to PyeongChang thanks to a crowdfunding initiative.

According to BBC analyst Nicola Minichiello, who finished ninth in the same event at the Turin games in 2006, the British women could improve on their result with the right support – and tech.

“These are the next generation. To put it in perspective. Mica McNeill has a good sled but it’s not compared to the BMWs, the sleds of the Germans… You’re always looking at technology.” 

 

Perfecting the push-off

Having a fast start, known as the push-off, is crucial to later speed gained down the track. A team of researchers led by the Korea Institute of Sport Science in Seoul aimed to help the Korean bobsled team by developing a force measurement system for practicing the push-off. As reported in the Journal of Sports Engineering and Technology, load cells we used in the push bar and handle to analyse the forces exerted by the two person crews.

“The developed system comprised eight load cells, an encoder, four cameras, and a data acquisition device and was installed on a test sled. Two load cells were installed in each of the brakeman’s push handle and the driver’s side push bar, and two load cells were located on each of the right and left ends of the push bar. The operator could adjust the sampling rate of each load cell from 50 to 200 samples/s. The motion of the crew member was recorded with the four cameras. The sled speed was recorded along with the force data. 

For convenient monitoring and analysis of the measured data, the four camera images were merged into a single video image, and the force data were plotted on this merged image. This image contained all of the measured data and was transmitted wirelessly to a monitor at a remote site in real time.”

 

Curling brushes and load cells

Load cells also have played their part in the sport that lasts all Winter Games long – curling. It’s certainly the only sport we know of where a brush is a crucial part of the game,. A team from the Kitami Institute of Technology used wireless load cells to:

“Measure the force during the sweeping on the sheet of ice using a wireless system and to confirm whether individual differences can be clarified in sweeping performance.”

The same team went on to research and develop a curling brush:

“For measuring forces exerted during the sweeping. We found that the forces that the curlers could exert during the sweeping were related to their physiques, competitive experiences and physical fitness levels (especially the arm strength).”

Unfortunately their summary report is only available in Japanese (!), but an illustration in the report shows where the load cells are located, which is enough for us!

 

Load cells for sports research

If you want to help you team sweep or slide to victory using load cells, give us a call. We have extensive experience in designing bespoke load cell systems for a whole variety of research projects, and would be happy to help do the same for yours.