Design of performance data through wearable technology for ankle movement upon football shots

Abstract

The motivation for this work came from observing amateur footballers making video recordings of themselves kicking footballs, to send to scouts. An opportunity was seen to apply wearable technology to capture additional kicking data and to provide feedback to the players to improve their kicking performance. The penalty kick was chosen as the setting for this research study. Initially inertial measuring unit sensors were used with participants to track ankle movements prior to the shots being taken. In this experiment, a simple kick study with Brunel University Women’s football team regarding their technique upon Ball Contact is analysed. The aim was to understand each player’s technique regarding their position profile and gameplay approach. A Decision matrix was created to rank each kicker against tracked features linking to selected biomechanics. After reviewing video and sensor data, 2 players showed differences compared to initial observed rank, with greater understanding of 1 player’s technique. Additional experiment involving force sensitive resistor sensors were placed around low/midsole and vamp regions of a football boot on a test rig. The test rig consisted of a swinging barbell which emulated a kicking motion, and video capture monitored the ball projection and velocity. This produced further performance data relating to the accuracy of ball projection in relation to the contact region of the boot. The midsole contact region showed greater accuracy of ball projection, and low vamp region showed greater ball velocity. A test of repeatability was done, to provide an estimation of variance, which further justified that midsole aids accuracy for inside foot shots. Mid to low vamp produced more consistent accuracy for laces shots. A new form of accuracy metric was considered which aided the sensor data to filter out error shots, by having greater outer sole tracking coverage to identify when the correct kicks were executed. User research outlined how the sensor data from experiments around the wearable technology used, formed a decision matrix which ranked attributes including kick to ball velocity, dependant on the user’s choice. A data framework was then designed which shows how ankle motion data transforms into meaningful shooting performance data. The key contribution of this work is to show that ankle motion prior to ball contact is an important parameter in football kicking biomechanics.