Research On Spatial Features Of Rhythmic Gymnasts Individual Clubs Apparatus Difficulty Based On Entropy

As promulgation of new rhythmic gymnastics scoring rules,researches focus on the changes of rhythmic gymnastics difficulty system.Apparatus difficulty,which is the reintroduced difficulty action in the new rules,represents the trends of rhythmic gymnastics individual event development.Apparatus manipulation variety,such as space utilization,moving trajectory,tempo variation and so on,is the vital point of apparatus difficulty.Since individual clubs event is the unique double apparatus event among all the rhythmic gymnastics individual events,its space utilization variety is quite important.The rhythmic gymnastics scoring rules require the space utilization diversity,but it lacks a quantitative indicator to space diversity of apparatus difficulty.In this paper,we propose a rhythmic gymnastics space utilization evaluation approach based on spatial distribution entropy.The time series of space distribution of apparatus difficulty action is formulated,and we use the time series to calculate the 3D spatial distribution entropy of apparatus difficulty action.The spatial distribution entropy is used to reflect the space diversity of apparatus difficulty of clubs events.The data of the 2017-2018 Rhythmic Gymnastics World Championships individual finals is used as the testing set.According to the results,we find that the top athletes have the larger entropy,which means the spatial states of their actions are more complicated,variable and uniform.The test results also show that the spatial distribution entropy is an effective quantitative indicator for space diversity evaluation of apparatus difficulty.The gap of the spatial distribution entropy of the apparatus difficulty among the world's elite rhythmic gymnasts has narrowed,which indicates that the overall technical level of apparatus has been improved.