Pattern Recognition in Cyclic and Discrete Skills Performance from Inertial Measurement Units

Abstract

The aim of this study is to compare and validate an Inertial Measurement Unit (IMU) relative to an optic system, and to propose methods for pattern recognition to capture behavioural dynamics during sport performance. IMU validation was conducted by comparing the motions of the two arms of a compass, which was equipped with IMUs and reflective landmarks detected by a multi-camera system. Spearman's rank correlation tests showed good correlations between the IMU and multi-camera system, especially when the angles were normalized. Bland-Altman plot, root mean square and the normalized pairwise variability index showed low differences between the two systems, confirming the good accuracy levels of the IMUs. Regarding pattern recognition, joint angle and limb orientation was respectively studied for 25 m during breaststroke swimming and 10 m of indoor rock climbing in athletes of various skill levels. Pattern recognition was also conducted on a macroscopic parameter that captured inter-limb coordination. IMUs revealed the potential to assess movement and coordination variability between and within individuals from joint angle measures in swimming and limb orientation time-series data in climbing.

Inertial Sensor Technology for Elite Swimming Performance Analysis: A Systematic Review

“…A limited number of examples of using inertial sensor technology to measure joint angles can be found in the literature [ 22 , 44 , 50 , 94 , 95 ]. Single sensor units have been used to determine the pitch and roll angles of the swimmer using positions on the head [ 44 ] and back [ 50 ] ( Figure 22 ).…”

“…Other studies have used multiple sensors to measure joint angles [ 94 , 95 ]. Processes typically involve methods to represent the three dimensional orientations and rotations of the swimmers limbs, including a rotation matrix [ 44 ]; Euler angles [ 94 ] or quaternions [ 95 ] and these methods have been used to analyse human movement in other sporting and health related contexts [ 110 , 111 , 112 , 113 , 114 ]. Seifert, L’Hermette, Komar, Orth, Mell, Merriaux, Grenet, Caritu, Hérault, Dovgalecs and Davids [ 95 ] demonstrated how this approach could be used to enhance the coaching process by assessing different patterns of limb coordination.…”

“…It can be seen that the less proficient swimmer (on the left in Figure 23 ) displays almost simultaneous knee and elbow flexion and extension, whereas a more competent performer (on the right) has near maximum extension of the elbow when the knees are at full extension, allowing for swimming speed to be better maintained throughout the stroke cycle. Seifert, L’Hermette, Komar, Orth, Mell, Merriaux, Grenet, Caritu, Hérault, Dovgalecs and Davids [ 95 ] reported a variation of between 0.09 rad and 0.15 rad from the criterion measure using this method. Phillips, Forrester, Hudson and Turnock [ 94 ] also used four sensor locations to measure joint angles, focusing on butterfly kicking technique.…”

Environmental Design Shapes Perceptual-motor Exploration, Learning, and Transfer in Climbing

“…A third IMU was also placed on the artificial climbing wall to locate it on the Earth reference frame. Our IMUs corresponded to a combination of a tri-axial accelerometer (±8G), tri-axial gyroscope (1600°.s −1 ) and a tri-axial magnetometer ( MotionPod , Movea © , Grenoble, France) and have been already used to assess the measure of jerk of the hip trajectory during a climbing task (Seifert et al, 2014b ), and limb 3D direction (Seifert et al, 2014a ). Wireless transmissions to a controller enabled recording by MotionDevTool software (Movea © , Grenoble, France).…”

Coordination in Climbing: Effect of Skill, Practice and Constraints Manipulation

“…This differentiation of 19 conditions clearly has influenced the material properties and specialised equipment that climbers have been tested using, which predominantly involve man-made holds, but have included ice [42,109,108,51,26,97] and rock [24]. Additionally, research on climbing under top-rope conditions far outweigh studies under lead rope conditions where only five studies have involved lead rope constraints [44,36,55,86].…”