Testing of Cross-country Ski Shoes Using an Industrial Robot

INTRODUCTION Shoes are an important part of the sports equipment. They are constantly developed and improved. This is especially evident for winter sports, alpine skiing, cross-country skiing, skating, etc. Usually, the design of ski boots is based on a trial and error method, where each prototype is tested on the outdoor terrain. This approach is very time consuming and expensive. It is affected by the personal judgement of the tester. Recently, sport scientists, athletes and shoe manufacturers have raised the possibility that a cross-country ski boot can enhance the energy efficiency of the ski runner. They suspect that very small changes in energy return characteristics can help to improve the sports results. However, it is not yet clear how to measure this benefit (Shorten, 1993). In the past a numerous studies were done dealing with the testing of running shoes (Nigg 1986, Barry and Milburn 1999), but very few were dealing with the alpine skiing boots and cross-country skiing boots. In the paper, we propose an approach to the sports equipment testing based on the simulation of the sport activity with an industrial robot. It consists of two major phases: a measurement phase and a simulation phase. In the measurement phase we capture the forces and trajectories that occur during the sport activity. The sport activity is recorded also with a video camera, which enables identification of the movements during the simulation phase. In the simulation phase, we use an industrial robot that repeats the captured motion. With additional measurement equipment, various forces, tensions, vibrations, etc. can be measured at any part of the sport shoe. The main benefit of this approach is that various shoes can be measured and compared under the same conditions. Additionally, laboratory environment makes possible measurements that are very difficult or impossible to perform on the terrain. The method was successfully applied for the testing of cross-country and alpine skis (Nemec, 98) Here, application to the cross-country ski boots will be described. The efficiency of the proposed method is illustrated by comparing two types of the ski boots. Test trajectory was obtained from an elite cross-country skier.